Technical Field
The present invention relates to a combination weigher
which feeds objects to be weighed to a packaging machine or the like.
Background Art
Objects to be weighed, such as detergents and confectionary,
which are weighed by a combination weigher to have a predetermined weight, are typically
packaged by a packaging machine. A schematic construction of a conventional combination
weigher which weighs objects to be weighed is shown in Fig. 12. In addition, a schematic
construction of the packaging machine disposed below the combination weigher is
shown in Fig. 13.
The combination weigher shown in Fig. 12, whose operation
is entirely controlled by a control unit 20, is provided with a dispersion feeder
1 at the center of an upper part of the combination weigher. The dispersion feeder
1 has a conical shape and serves to radially disperse objects to be weighed supplied
from an external supplying device by vibration. Around the dispersion feeder 1,
linear feeders 2 are provided to transfer the objects to be weighed sent from the
dispersion feeder 1 into the corresponding feeding hoppers 3 by vibration. The plurality
of feeding hoppers 3 and weighing hoppers 4 are disposed below the linear feeders
2 and are arranged circularly in such a manner that each feeding hopper 3 and each
weighing hopper 4 correspond to the associated one of the linear feeders 2. The
feeding hoppers 3 receive the objects to be weighed transferred from the linear
feeders 2 and open their gates when the weighing hoppers 4 disposed therebelow become
empty to feed the objects to be weighed to the weighing hoppers 4. Weight sensors
41 such as load cells are attached to the weighing hoppers 4, and measure the weight
of the objects to be weighed inside the weighing hoppers 4. The control unit 20
performs combination calculation to select a combination of hoppers to discharge
the objects to be weighed therefrom from the plurality of weighing hoppers 4. The
objects to be weighed are discharged from the weighing hoppers 4 corresponding to
the combination onto the collecting chute 6. The collecting chute 6 is provided
below the weighing hoppers 4. The objects to be weighed discharged from the weighing
hoppers 4 slide down on the collecting chute 6, and are sent out from an outlet
provided in a lower portion thereof to the packaging machine shown in Fig. 13.
In the packaging machine, bags are manufactured while the
objects to be weighed discharged from the combination weigher are charged into the
bags and packaged. In this packaging machine, a sheet of wrapping material 50 withdrawn
from a roll of a wrapping material is caused to be wound around a tube 51 by a former
52 to form a cylindrical shape and is suctioned by a pulldown belt 53 to be transferred
downwardly, and the superposed vertical edges of the cylindrical wrapping material
50 are sealed (sealing by fusion adhesion) by a vertical sealing machine 54. The
objects to be weighed which have been weighed are then charged into the cylindrical
wrapping material 50 through the tube 51, and a horizontal sealing machine 55 disposed
below the tube 51 seals horizontally across the upper end of a preceding bag and
the lower end of a following bag (sealing by fusion adhesion). By this horizontal
sealing, the preceding bag is completed with its upper and lower ends sealed since
the lower end of the preceding bag has been sealed by the previous horizontal sealing.
The center of the horizontally sealed portion is then cut by a cutter built in the
horizontal sealing machine 55 so that the preceding bag and the following bag are
separated from each other.
Patent document 1:
Japanese Examined Patent Publication No. Hei. 8  1395
Disclosure of the Invention
Problems to be Solved by the Invention
In order to adapt the above mentioned conventional combination
weigher to a packaging machine operated at a high speed, discharge cycle (interval
of the timing of the start of sequential discharging) in which the objects to be
weighed are discharged to the packaging machine needs to be shortened. To this end,
conventionally, the number of the weighing hoppers is increased to a certain number
to constitute socalled double shift or triple shift rather than single shift so
that the discharge cycle is shortened to 1/2 or 1/3 of that of the single shift
to be adapted to such a packaging machine. Although this configuration can shorten
the discharge cycle, it does not shorten the length from the upper end to the lower
end of the batch of the objects to be weighed discharged from the collecting chute
6, or shorten the time taken to accommodate the objects to be weighed discharged
from the combination weigher into the bag (bag of the packaging machine). In the
highspeed operated packaging machine, the cycle time from one sealing by the horizontal
sealing machine 55 to another is short. For this reason, if horizontal sealing is
carried out before all of the objects to be weighed discharged from the combination
weigher have been accommodated into the bag, the objects to be weighed are disadvantageously
stuck in the sealed portion.
The present invention has been made to solve the above
mentioned problems, and its object is to provide a combination weigher which can
shorten each discharge time and discharge cycle of the objects to be weighed and
can be adapted to a packaging machine operated at a high speed.
Means for Solving the Problems
In order to achieve the above described object, a combination
weigher of the present invention comprises a plurality of base groups including
a plurality of circulararcshaped hopper lines into which a combination hopper
line including a plurality of combination hoppers which are circularly arranged
and fed with objects to be weighed are divided; a plurality of collecting chutes
which are respectively disposed below the base groups to respectively correspond
to the base groups and have outlets at lower parts thereof, each of the collecting
chutes collecting the objects to be weighed discharged from the combination hopper
in the corresponding base group and discharging the objects to be weighed from the
outlet; a plurality of collecting hoppers respectively provided at the outlets of
the collecting chutes to respectively correspond to the base groups and the collecting
chutes, the collecting hoppers temporarily accumulating the objects to be weighed
discharged from the outlets of the collecting chutes and thereafter discharging
the objects to be weighed; and a control means; wherein the control means is configured
to perform a combination process to determine p (p: plural number less than the
number of all base groups) of discharge groups each including one or more base groups
and perform combination calculation based on weights of the objects to be weighed
which have been fed into the combination hoppers in the discharge groups to select
combination hoppers forming combination in which total weight of the objects to
be weighed with respect to a target weight is in an allowable range and a difference
with respect to the target weight is smallest, an internal discharge process to
cause the combination hoppers forming all combinations selected in the discharge
groups to discharge the objects to be weighed simultaneously; and an external discharge
process to sequentially select the discharge groups and to cause the collecting
hoppers corresponding to the base groups including the combination hoppers forming
combinations in the discharge groups to discharge the objects to be weighed, according
to the selected sequence.
In accordance with this configuration, a plurality of base groups into which the
combination hopper line is divided, a plurality of collecting chutes, and a plurality
of collecting hoppers are provided to respectively correspond to each other, a plurality
of discharge groups each including one or more base groups are determined, and the
combination hoppers forming the combination in the respective discharge groups found
by the combination calculation discharge the objects to be weighed simultaneously.
The objects to be weighed are fed into the corresponding collecting hopper through
the corresponding collecting chute and are temporarily accumulated therein. Then,
the objects to be weighed are discharged in a state of gathering together satisfactorily
sequentially from the collecting hoppers in the respective discharge groups. Therefore,
each discharge time of the objects to be weighed discharged from each collecting
hopper can be shorted, the discharge cycle can be shortened, and a highspeed operation
is achieved. As a result, the combination weigher of the present invention can be
adapted to the packaging machine operated at a high speed, and the objects to be
weighed can be prevented from being stuck inside the packaging machine.
The combination process may includes a process to determine (p1) discharge
groups by performing, (p1) times, a series of processes including a first
process to find all combination groups each including a combination of k (k : integer
of one or more) base groups which do not belong to the discharge groups; a second
process to perform, with respect to each of the combination groups, combination
calculation based on the weights of the objects to be weighed which have been fed
into the combination hoppers within the combination groups to find combination hoppers
forming first combination in which a total weight of the objects to be weighed with
respect to the target weight is in the allowable range and a difference with respect
to the target weight is smallest and to determine total weight of the objects to
be weighed in the combination hoppers forming the first combination as optimal combination
weight of the combination group; and a third process to select the combination group
whose optimal combination weight has a smallest difference with respect to the target
weight from all combination groups and to determine the selected combination group
or the base group including the combination hoppers forming the first combination
within the selected combination group as the discharge group; and a process to perform
combination calculation based on the weights of the objects to be weighed which
have been fed into the combination hoppers in base groups which do not belong to
the (p 

1) discharge groups to find combination hoppers forming a second combination
in which a total weight of the objects to be weighed with respect to the target
weight is in the allowable range and a difference with respect to the target weight
is smallest and to determine the base groups which do not belong to the (p 
1) discharge groups or the base group including the combination hoppers forming
the second combination as pth discharge group (combination process A).
By performing the combination process A, combination precision
(weighing precision) in each discharge group can be improved.
The combination process may includes a process to find
all discharge candidate group sets in which at least one discharge candidate group
belonging to one discharge candidate group set is different from that belonging
to another discharge candidate group set and to calculate a total of differences
in each of the discharge candidate group sets, by repeating, plural times, a loop
process including a first combination process to determine (p  1) discharge
candidate groups each including one or more base groups and to find optimal combination
weight in each of the discharge candidate groups; a second combination process to
determine pth discharge candidate group including one or more base groups and to
find optimal combination weight of the pth discharge candidate group and add the
pth discharge candidate group and the (p 1) discharge candidate
groups to form one discharge candidate group set; and a calculation process to calculate
a total of differences between the optimal combination weights and the target weight
with respect to the p discharge candidate groups in the discharge candidate group
set; and a process to determine, as the discharge groups, the p discharge candidate
groups in the discharge candidate group set in which the total of differences is
smallest, which are selected from the discharge candidate group sets; the first
combination process in a loop process with the same ordinal number, in the loop
process repeated plural times, is a process to determine the (p 1) discharge
candidate groups by repeating, (p 1) times, a series of processes including
a first process to find arbitrary combination group including a combination of k
(k : integer of one or more) base groups which do not belong to the discharge candidate
groups by a second process; a second process to perform combination calculation
with respect to the combination groups, based on the weights of the objects to be
weighed which have been fed into the combination hoppers within the combination
groups to select combination hoppers forming first combination in which a total
weight of the objects to be weighed with respect to the target weight is in the
allowable range and a difference with respect to the target weight is smallest and
to determine the combination group or the base groups including the combination
hoppers forming the first combination within the combination group as one discharge
candidate group and the total weight of the objects to be weighed in the combination
hoppers forming the first combination as optimal combination weight of the discharge
candidate group, the second combination process in the loop process with the same
ordinal number, is a process to perform combination calculation based on the weights
of the objects to be weighed which have been fed into the combination hoppers within
base groups which do not belong to the (p 1) discharge candidate groups to select
combination hoppers forming second combination in which total weight of the objects
to be weighed with respect to the target weight is in the allowable range and a
difference with respect to the target weight is smallest and to determine the base
groups which do not belong to the (p 1) discharge candidate groups or the
base groups including the combination hoppers forming the second combination as
the pth discharge candidate group and the total weight of the objects to be weighed
in the combination hoppers forming the second combination as optimal combination
weight of the pth discharge candidate group; and to add the pth discharge candidate
groups and (p1) discharge candidate groups to form one discharge candidate group
set (combination process B).
By performing the combination process B, combination precision (weighing precision)
in each discharge group can be improved. In addition, in contrast to the case where
the combination process A is performed, the total weight of the optimal combination
weights of the p discharge groups can be reduced, and thus consumption amounts of
the objects to be weighed can be reduced.
In the case of the combination process A, in the process to determine the (p  1)
discharge groups by performing the series of processes including the first, second,
and third processes (p  1) times, the number k of the base groups forming
the combination group may be changed at least once.
In the case of the combination process B, in the first
combination process to determine the (p  1) discharge candidate groups by
performing the series of processes including the first and second processes (p
1) times, the number k of the base groups forming the combination group
may be changed at least once.
The number of the discharge groups determined in the combination
process may be set to two (p = 2) or three (p = 3). When the number of the discharge
groups is two, the objects to be weighed can be discharged twice in one weighing
cycle, while when the number of the discharge groups is three, the objects to be
weighed can be discharged three times in one weighing cycle.
The combination hoppers included in the base groups may
be set to be equal in number. In this case, the total number of the combination
hoppers can be divided by the number of base groups.
The combination hoppers included in at least one base group
of all base groups may be different in number from the combination hoppers included
in another base group. Thus, the combination hoppers included in the base groups
is not necessarily equal in number.
The combination hoppers may be weighing hoppers which weigh
weights of the objects to be weighed fed into the weighing hoppers.
The combination hopper line may include upper and lower
combination hopper lines; and the combination hoppers on the upper combination hopper
line may be weighing hoppers which weigh weights of the objects to be weighed fed
into the weighing hoppers; the combination hoppers on the lower combination hopper
line may be memory hoppers which are provided to respectively correspond to the
weighing hoppers and are fed with the objects to be weighed which have been weighed
by the weighing hoppers, and the weighing hoppers may be each capable of selectively
discharging the objects to be weighed to the corresponding memory hopper or the
corresponding collecting chute.
The combination weigher may further comprise a plurality
of weighing hoppers disposed above the combination hoppers to respectively correspond
to the combination hoppers, for weighing weights of the objects to be weighed fed
into the weighing hoppers; wherein the combination hoppers are memory hoppers each
including two accommodating chambers into which the objects to be weighed which
have been weighed by the weighing hopper are fed, the accommodating chambers being
capable of independently discharging the objects to be weighed; wherein the weighing
hoppers are each capable of selectively discharging the objects to be weighed to
one of the two accommodating chambers of the corresponding memory hopper; and wherein
the control means is configured to perform combination calculation in the combination
process based on weights of the objects to be weighed which have been fed into the
accommodating chambers of the memory hoppers to determine combination of the accommodating
chambers of the memory hoppers, and to cause the accommodating chambers forming
the determined combination to discharge the objects to be weighed in the internal
discharge process and to cause the collecting hopper corresponding to the base groups
including the memory hoppers having the accommodating chambers forming the determined
combination to discharge the objects to be weighed in the external discharge process.
The combination hoppers may be weighing hoppers each of
which includes two weighing chambers and weighs weights of the objects to be weighed
which have been fed into the weighing chambers, the weighing chambers being independently
discharging the objects to be weighed; and the control means may be configured to
perform combination calculation in the combination process based on the weights
of the objects to be weighed which have been fed into the weighing chambers of each
weighing hopper to determine combination of the weighing chambers of the weighing
hopper and to cause the weighing chambers forming the determined combination to
discharge the objects to be weighed in the internal discharge process and to cause
the collecting hopper corresponding to the base groups including the weighing hoppers
having the weighing chambers forming the determined combination to discharge the
objects to be weighed in the external discharge process.
The combination weigher may further comprise a plurality
of weighing hoppers disposed above the combination hoppers to respectively correspond
to the combination hoppers, each of which includes two weighing chambers and weighs
weights of the objects to be weighed which have been fed into the weighing chambers,
the weighing chambers being independently discharging the objects to be weighed;
and wherein the combination hoppers may be memory hoppers each including two accommodating
chambers corresponding to the weighing chambers of the corresponding weighing hoppers,
the objects to be weighed which have been fed from the corresponding weighing chambers
being fed into the accommodating chambers, the accommodating chambers being capable
of independently discharging the objects to be weighed; wherein the control means
may be configured to perform combination calculation in the combination process
based on weights of the objects to be weighed which have been fed into the accommodating
chambers of the memory hoppers to determine combination of the accommodating chambers
of the memory hoppers, and to cause the accommodating chambers forming the determined
combination to discharge the objects to be weighed in the internal discharge process
and to cause the collecting hopper corresponding to the base groups including the
memory hoppers having the accommodating chambers forming the determined combination
to discharge the objects to be weighed in the external discharge process.
Effects of the Invention
The present invention is configured as described above,
and it is possible to provide a combination weigher which can reduce each discharge
time of the objects to be weighed, can shorten the discharge cycle and can be adapted
to the packaging machine operated at a high speed.
The above and further objects and features of the invention will more fully be apparent
from the following detailed description with accompanying drawings.
Brief Description of Drawings
 [Fig. 1] Fig. 1(a) is a schematic diagram of a cross section seen from laterally
of a combination weigher according to an embodiment of the present invention, and
Fig. 1(b) is a schematic diagram of collecting chutes and collecting hoppers of
the combination weigher according to the embodiment of the present invention as
seen from above;
 [Fig. 2] Fig. 2 is a schematic perspective view of the collecting hoppers shown
in Figs. 1(a) and 1(b);
 [Fig. 3] Fig. 3 is a flowchart of an operation of the combination weigher according
to a first embodiment of the present invention;
 [Fig. 4] Fig. 4 is a timing chart showing an example of the operation of the
combination weigher according to the embodiment of the present invention;
 [Fig. 5] Fig. 5 is a timing chart showing an example of the operation of the
combination weigher according to the embodiment of the present invention;
 [Fig. 6] Fig. 6 is a flowchart of an operation of a combination weigher according
to a second embodiment of the present invention;
 [Fig. 7] Fig. 7(a) is a schematic diagram of another example of collecting chutes
and collecting hoppers in the combination weigher according to the embodiment of
the present invention as seen from laterally, and Fig. 7(b) is a schematic diagram
of the collecting chutes and collecting hoppers of another example seen from above;
 [Fig. 8] Fig. 8 is a schematic diagram showing another example of hoppers for
use in the combination weigher according to the embodiment of the present invention;
 [Fig. 9] Fig. 9 is a schematic diagram showing another example of hoppers for
use in the combination weigher of the embodiment of the present invention;
 [Fig. 10] Fig. 10 is a schematic diagram showing another example of hoppers
for use in the combination weigher of the embodiment of the present invention;
 [Fig. 11] Fig. 11 is a schematic diagram showing another example of hoppers
for use in the combination weigher according to the embodiment of the present invention;
 [Fig. 12] Fig. 12 is a schematic diagram showing a construction of the conventional
combination weigher; and
 [Fig. 13] Fig. 13 is a schematic diagram showing a construction of a packaging
machine disposed below the combination weigher.
Description of the Reference Numerals
 1
 Dispersion feeder
 2
 Linear feeder
 3
 Feeding hopper
 4
 Weighing hopper
 5
 Memory hopper
 6A6D
 Collecting chutes .
 7A7D
 Collecting hoppers
 7a7d
 Collecting hoppers
 21
 Control unit
Best Mode for Carrying Out the Invention
Hereinafter, preferred embodiments of the present invention
will be described with reference to the drawings.
(Embodiment 1)
Fig. 1(a) is a schematic diagram of a cross section of
a combination weigher according to an embodiment of the present invention as seen
from laterally, and Fig. 1(b) is a schematic diagram of collecting chutes and collecting
hoppers of the combination weigher according to the embodiment of the present invention
as seen from above.
The combination weigher of this embodiment is provided
with a dispersion feeder 1 at the center of an upper part of the combination weigher.
The dispersion feeder 1 has a conical shape and serves to radially disperse objects
to be weighed supplied from the external supplying device by vibration. Around the
dispersion feeder 1, linear feeders 2 are provided to transfer the objects to be
weighed sent from the dispersion feeder 1 into each of feeding hoppers 3 by vibration.
The plurality of feeding hoppers 3 and weighing hoppers 4 are disposed below the
linear feeders 2 and are arranged circularly in such a manner that each feeding
hopper 3 and each weighing hopper 4 correspond to the associated one of the linear
feeders 2. The feeding hoppers 3 receive the objects to be weighed transferred from
the linear feeders 2 and open their gates when the weighing hoppers 4 disposed therebelow
become empty to feed the objects to be weighed to the weighing hoppers 4. Weight
sensors 41 such as load cells are attached to the weighing hoppers 4, and measure
the weights of the objects to be weighed inside the weighing hoppers 4. The configuration
described above is the same as that of the prior art example shown in Fig. 12. In
this embodiment, collecting chutes 6A6D which are four separate elements are provided
below the weighing hoppers 4, and collecting hoppers 7A7D are provided at the outlets
of the collecting chutes 6A6D, respectively. A chute 61 having a substantially
inverted conical shape is partitioned into four chutes by partition walls 62, forming
the collecting chutes 6A6D. Each of these four collecting chutes 6A6D is positioned
to correspond to 1/4 in number of all the weighing hoppers 4 arranged circularly
to receive the objects to be weighed discharged from 1/4 in number of the weighing
hoppers 4. The objects to be weighed discharged from the weighing hoppers 4 slide
down on the collecting chutes 6A6D corresponding to the weighing hoppers 4 and
are temporarily accumulated in the collecting hoppers 7A7D. Fig. 2 shows a simplified
perspective view of the collecting hoppers 7A7D. Each of the collecting hoppers
7A7D constitutes a portion for accommodating the objects to be weighed by a side
plate 71, two partition plates 72 and a gate 73. Each of the partition plates 72
is shared by adjacent collecting hoppers, and thus four collecting hoppers 7A7D
are integrally formed. The objects to be weighed are discharged from each of the
collecting hoppers 7A7D by opening the gate 73 outward (for example, the direction
in which the gate 73 of the collecting hopper 7A is opened is shown by an arrow
74). The control unit 21 controls the operation of the entire combination weigher
and also performs combination process. A packaging machine shown in Fig. 13 is disposed
below this combination weigher, and the objects to be weighed discharged from each
of the collecting hoppers 7A7D are fed into an inlet which is a widened upper part
of a cylindrical tube 51 of the packaging machine.
Subsequently, the operation of the combination weigher of this embodiment will be
described. In this embodiment, for example, in the configurations of Fig. 1(a) and
1(b), the four collecting chutes 6A to 6D respectively correspond to the collecting
hoppers 7A to 7D, and it is assumed that the weighing hoppers 4 corresponding to
the collecting chute 6A and the collecting hopper 7A is a base group A, the weighing
hoppers 4 corresponding to the collecting chute 6B and the collecting hopper 7B
is a base group B, the weighing hoppers 4 corresponding to the collecting chute
6C and the collecting hopper 7C is a base group C, and the weighing hoppers 4 corresponding
to the collecting chute 6D and the collecting hopper 7D is a base group D.
The control unit 21 performs combination process described later in detail to find
a plurality of discharge groups formed by combining the base groups. When determining
each discharge group, the control unit 21 performs combination calculation based
on measured values (weights of the objects to be weighed inside the weighing hoppers
4 which are measured by the weight sensors 41) of the weighing hoppers 4 belonging
to the discharge group, to determine a combination of the hoppers which will discharge
the objects to be weighed, which are selected from the weighing hoppers 4 belonging
to that discharge group. By opening and closing the gates of the weighing hoppers
4 corresponding to the determined combination, the objects to be weighed are discharged
onto the collecting chute and are accumulated in the collecting hopper. Furthermore,
the control unit 21 sequentially opens the gates of the collecting hoppers (7A to
7D) respectively corresponding to the discharge groups in response to a feed command
signal from the packaging machine, thereby discharging the objects to be weighed
from the collecting hoppers whose gates have been opened, and feeding them into
the cylindrical tube 51 of the packaging machine.
Fig. 3 is a flowchart showing the operation of the combination
weigher of this embodiment. It is assumed that the number of discharging of the
objects to be weighed to the outside (e.g., packaging machine) in one weighing cycle
is p (p: plural number). The above mentioned combination process is steps S1 to
S8. The control unit 21 contains a memory therein, and is configured to store in
the memory required information found in the combination process (information as
to which base group weighing hoppers form the combination groups and the discharge
groups described later, information indicating the weighing hoppers forming optimal
combination, information indicating optimal combination weight, etc).
First of all, in step S1, n is initialized to 1. n indicates
the number of discharge groups found in step S5 described later.
In step S2, combination groups each including a combination
of k base groups which do not belong to the determined discharge group are
found. Since there is no determined discharge group initially, groups each including
a combination of k base groups selected from all the base groups are determined
as the combination groups.
In step S3, one combination group other than the selected
combination group is selected, and combination calculation is performed based on
the measured values of the weighing hoppers 4 within that combination group to select
the weighing hoppers 4 forming a combination (optimal combination) in which a total
measured value with respect to the target weight is in an allowable range and a
difference with the target weight is smallest, and to determine the total measured
value of the weighing hoppers 4 forming the optimal combination as an optimal combination
weight. Since there is no selected combination group initially, an arbitrary combination
group is selected from all combination groups, and the above combination calculation
is performed.
In step S4, it is determined whether or not there is a
combination group that has not been selected for the combination calculation in
step S3, among the combination groups selected in step S2. If it is determined that
there is in step S4, step S3 is repeated for all the combination groups, and thereafter
the process moves to step S5.
In step S5, a combination group whose optimal combination
weight is closest to the target weight is found from all the combination groups,
and the base group including the weighing hoppers 4 forming the optimal combination
within that combination group is determined as nth discharge group.
Then, in step S6, it is determined whether or not the
n is equal to p  1, and if it is determined that the n is not equal
to p  1, one is added to n in step S7, and the process from step
S2 is repeated, whereas if it is determined that the n is equal to p 1 in
step S6, the process moves to step 8. That is, steps S2 to S5 are repeated until
p  1 discharge groups are determined.
In step S8, the combination calculation is performed based
on the measured values of the weighing hoppers 4 within the base groups which do
not belong to the p 1 discharge groups to select the weighing hoppers 4 forming
a combination (optimal combination) in which a total measured value with respect
to the target weight is in an allowable range and a difference with the target weight
is smallest and to determine the total measured value of the weighing hoppers 4
forming the optimal combination as an optimal combination weight. The base groups
including the weighing hoppers 4 forming the optimal combination is determined as
pth discharge group.
Through the combination process in step S1 through S8,
p discharge groups are determined.
In step S9, gates of the weighing hoppers 4 forming the optimal combination in the
p discharge groups are opened simultaneously to feed the objects to be weighed to
the collecting hoppers.
In step S10, every time the feed command signal is received
from, for example, the packaging machine, the gates of the collecting hoppers corresponding
to the respective discharge groups are sequentially opened to discharge to the objects
to be weighed to the packaging machine. In brief, every time the feed command signal
is received from the packaging machine, the objects to be weighed having the optimal
combination weight are discharged from each discharge group.
A case where the above described process, specifically,
the combination process in step S1 to S8 is applied to the configurations of Fig.
1(a) and 1(b) will be described in detail. Here it is assumed that each of base
groups A to D includes six weighing hoppers 4, the combination group is formed by
combining two base groups (k = 2), four weighing hoppers 4 are selected as the weighing
hoppers 4 forming the optimal combination, and the number of discharging of the
objects to be weighed in one weighing cycle is two (p = 2).
First of all, in step S1, n is initialized to 1.
In step S2, since there is no determined discharge group
initially, two base groups selected from all the base groups A to D, for example,
the base groups A and B are combined to form one combination group. In the same
manner, combination groups of the base groups A and C, the base groups A and D,
the base groups B and C, the base groups B and D, and the base groups C and D are
created, and thus 6 (= 4C2) combination groups in total are found.
In step S3, since there is no selected combination group
initially, an arbitrary combination group, for example, the combination group of
the base groups A and B, is selected from all the combination groups, the combination
calculation is performed for that combination group to select four weighing hoppers
4 forming the optimal combination and to determine the total measured value of the
weighing hoppers 4 forming the optimal combination as the optimal combination weight.
In this case, the weighing hoppers 4 forming the optimal combination are selected
from 495 (= 12C4) combinations.
In step S4, if it is determined that there are any combination
groups which have not been selected as the combination groups for which the combination
calculation is performed in step S3 among the combination groups found in step S2,
step S3 is repeated. In this manner, the weighing hoppers 4 forming the optimal
combination and the optimal combination weight are found for each of the six combination
groups.
In step S5, the combination group whose optimal combination weight is closest to
the target weight is selected from all the combination groups, and the base groups
including the weighing hoppers 4 forming the optimal combination within that combination
group is determined as a first (n = 1) discharge group. The weighing hoppers 4 forming
the optimal combination within that discharge group are selected from 4C2 X 12C4
= 2970 combinations. Since each base group includes six weighing hoppers 4, the
four weighing hoppers 4 selected to form the optimal combination may belong to both
or one of, for example, the base groups A and B forming that combination group.
If the weighing hoppers 4 forming the optimal combination belong to both of the
base groups A and B, then the base groups A and B are the discharge groups. If the
weighing hoppers 4 belong only to the base group A, then only the base group A is
the discharge group, whereas if the weighing hoppers 4 belong only to the base group
B, then only the base group B is the discharge group.
Then, in step S6, it is determined whether or not the n is equal to
p  1. In this example, n = 1, p = 2, and p  1 = 1.
Since it is determined that n is equal to p 1, the process moves
to step 8.
If the base groups B and C have been determined as the
discharge group in step S5, in step S8, the combination calculation is performed
based on the measured values of the weighing hoppers 4 within the base groups A
and D which do not belong to the discharge group to select four weighing hoppers
4 forming the optimal combination and to determine a total measured value of the
weighing hoppers 4 forming that optimal combination as the optimal combination weight.
And, the base groups including the weighing hoppers 4 forming that optimal combination
are determined as second discharge group. If the base group A has been determined
as the discharge group in step S5, then the combination calculation is performed
based on the measured values of the weighing hoppers 4 within three base groups
B, C, and D which do not belong to the discharge group to select four weighing hoppers
4 forming the optimal combination and to determine the total measured value of the
weighing hoppers 4 forming that optimal combination as optimal combination weight.
And, the base group including the weighing hoppers 4 forming the optimal combination
is determined as the second discharge group. Through the above mentioned process,
two discharge groups are determined.
Subsequently, a combination process in step S1 to S8 in a case where there are seven
base groups (seven collecting chutes and seven collecting hoppers) will be described.
Here it is assumed that each of seven base groups A to G includes four weighing
hoppers 4, the combination group is formed by combining two base groups (k = 2),
four weighing hoppers 4 are selected as the weighing hoppers 4 forming the optimal
combination, and the number of discharging of the objects to be weighed in one weighing
cycle is three (p = 3).
First of all, in step S1, n is initialized to 1.
In step S2, since there is no determined discharge group
initially, combinations of two base groups selected from the base groups A to D,
21 (= 7C2) combination groups including the base groups A and B, A and C, ... A
and G, B and C, B and D, ..., B and G, C and D, ... F and G, are found.
In step S3, as in the case where the number of base groups
is four, since there is no determined discharge group initially, an arbitrary combination
group, for example, the combination group of the base groups A and B, is selected
from all the combination groups, the combination calculation is performed for that
combination group to select weighing hoppers 4 forming the optimal combination and
to determine the total measured value of the weighing hoppers 4 forming the optimal
combination as the optimal combination weight. In this case, the weighing hoppers
4 forming the optimal combination are selected from 70 (= 8C4) combinations.
In step S4, if it is determined that there are any combination
groups which have not been selected as the combination groups for which the combination
calculation is performed in step S3, among the combination groups found in step
S2, step S3 is repeated. In this manner, the weighing hoppers 4 forming the optimal
combination and the optimal combination weight are found for each of the twenty
one combination groups.
In step S5, the combination group whose optimal combination
weight is closest to the target weight is found from all the combination groups,
and the base group including the weighing hoppers 4 forming the optimal combination
within that combination group is determined as a first (n = 1) discharge group.
The weighing hoppers 4 forming the optimal combination within that discharge group
are selected from 7C2 X 8C4 = 1470 combinations. Since each base group includes
four weighing hoppers 4, the four weighing hoppers 4 selected to form the optimal
combination may belong to both or one of, for example, the base groups A and B forming
that combination group.
Then, in step S6, it is determined whether or not the n
is equal to p1. In this example, n = 1, p = 3, and
p  1 = 2. Since it is determined that n is not equal to p  1, in
step S7, n = 2 is set and the process returns to step S2.
If the base groups A and B have been determined as the discharge group in step S5,
in step S2, 10 ( = 5C2) combination groups including two base groups selected from
five base groups C to G, excluding the base groups A and B are found. Also, if only
one base group (e.g., base group A) is determined as the discharge group, then 15
( = 6C2) combination groups including two base groups selected from six base groups
B to G, excluding the base group A are found.
Following this, steps S3 to S5 are performed in the same manner as described above
to determine second (n = 2) discharge group. Then in step S6, n = 2,
p = 3, and p  1 = 2. Since it is determined that n is equal
to p 1, the process moves to step 8.
If the base group A is determined as the first discharge group and the base groups
B and C are determined as the second discharge group, in step S8, the combination
calculation is performed based on the measured values of the weighing hoppers 4
within the base groups D to G which do not belong to the discharge groups to select
the weighing hoppers 4 forming the optimal combination and to determine a total
measured value of the weighing hoppers 4 forming the optimal combination as optimal
combination weight. And, the base group including the weighing hoppers 4 forming
the optimal combination is determined as the third discharge group. Through the
above process, three discharge groups are determined.
Subsequently, a combination process in step S1 to S8 in a case where there are three
base groups (three collecting chutes and three collecting hoppers) will be described.
Here it is assumed that each of the three base groups A to C includes eight weighing
hoppers 4, four weighing hoppers 4 are selected as the weighing hoppers 4 forming
the optimal combination, and the number of discharging of the objects to be weighed
in one weighing cycle is two (p = 2). When the number of base groups is four or
more, it is desirable to combine plural base groups to form a combination group.
However, when the number of base groups is three as in this example, each combination
group includes one base group (k = 1). In other words, the combination group is
identical to the base group.
First of all, in step S1, n is initialized to 1.
In step S2, since there is no determined discharge group
initially, the base groups A, B, and C are combination groups.
In step S3, as in the case where the number of base groups
is four, since there is no selected combination group initially, an arbitrary combination
group, for example, the combination group consisting of the base group A is selected
from all the combination groups, the combination calculation is performed for that
combination group to select weighing hoppers 4 forming the optimal combination and
to determine a total measured value of the weighing hoppers 4 forming the optimal
combination as the optimal combination weight.
Depending on step S4, step S3 is repeated. In this example,
weighing hoppers 4 forming the optimal combination and the optimal combination weight
are found from the combination groups each consisting of the base group A, B, or
C.
In step S5, the combination group whose optimal combination
weight is closest to the target weight is selected as first (n = 1) discharge group
from all the combination groups (A, B, and C). The weighing hoppers 4 forming the
optimal combination within that discharge group are selected from 3C1 × 8C4
= 210 combinations.
Then in step S6, n = 1, p = 2, and
p  1 = 1. Since it is determined that n is equal to p  1, the process
moves to step 8.
If the base group A has been determined as the first discharge
group, in step . S8, the combination calculation is performed based on the measured
values of the weighing hoppers 4 within the base groups B and C which do not belong
to the discharge groups to select the weighing hoppers 4 forming the optimal combination
and to determine a total measured value of the weighing hoppers 4 forming the optimal
combination as optimal combination weight. The base group including the weighing
hoppers 4 forming the optimal combination is determined as second discharge group.
Through the above process, two discharge groups are determined.
Whereas in the process shown in Fig. 3, the combination group whose optimal combination
weight is closest to the target weight is selected from all combination groups and
the base group including the weighing hoppers 4 forming the optimal combination
within that combination group is determined as the discharge group in step S5, the
combination group whose optimal combination weight is closest to the target weight
may alternatively be directly determined as the discharge group (in this case, the
combination precision may be reduced slightly). Also, whereas the combination calculation
is performed based on the measured values of the weighing hoppers 4 within the base
groups which do not belong to p  1 discharge groups to determine the base
group including the weighing hoppers 4 forming the optimal combination as
pth discharge groups in step S8, base groups which do not belong to the
p  1 discharge groups may alternatively be determined as the pth
discharge group (Note that the combination calculation is also performed in this
case). In these cases, in step S10, in the respective discharge groups for sequentially
discharging the objects to be weighed, only the collecting hoppers corresponding
to the base groups including the weighing hoppers 4 forming the optimal combination
within the discharge groups may be opened and closed to discharge the objects to
be weighed.
Furthermore, when step S2 is repeated, the number k of base groups forming the combination
group may be changed. For example, the number of base groups forming the combination
group in second step S2 may be set more than the number of base groups in first
step S2.
Fig. 4 is a timing chart of the operation of the combination weigher in the case
where two discharge groups are determined in the above mentioned combination process.
Whereas one weighing cycle and discharge timings of the collecting hoppers in that
weighing cycle are illustrated in Fig. 4, such operation is repeated in succession.
In Fig. 4, first and second discharge groups are first and second discharge groups
in the combination process, respectively. Alternatively, numbers (1, 2, 3, ...)
indicating discharge priority may be assigned to all base groups (or collecting
hoppers), and smallest numbers of the base groups belonging to the first and second
discharge groups in the combination process may be compared to each other, and the
discharge group including the base group with smaller number and the discharge group
including the base group with larger number may be determined as the first and second
discharge groups, respectively.
One weighing cycle in the combination weigher consists
of a discharge time t1, a stabilization time t2 and a combination time t3. The discharge
time t1 is a time taken to open and close the gates of the weighing hoppers 4 forming
the optimal combination operated to feed the objects to be weighed to the collecting
hopper and to open and close the gates of the feeing hoppers operated to feed the
objects to be weighed to these weighing hoppers 4. The stabilization time t2 is
a stabilization time of the weight sensors 41 attached to the weighing hoppers 4.
The combination time t3 is a time taken to perform the combination process and may
include wait time before the discharge time in next weighing cycle.
As shown in Fig. 4, the gate of the collecting hopper corresponding
to the first discharge group is opened to discharge the objects to be weighed to
the packaging machine in response to a feed command signal output from the packaging
machine at timing a, and the gate of the collecting hopper corresponding to the
second discharge group is opened to discharge the objects to be weighed to the packaging
machine in response to a feed command signal output from the packaging machine at
timing b.
By operating the discharge groups in a predetermined sequence with a difference
of T/2 time (T indicates time of one weighing cycle), the discharge can be performed
twice faster than in a case where the entire apparatus operates as a single combination
weigher, thereby allowing the combination weigher to be adapted to a packaging machine
operated at a high speed. Moreover, the objects to be weighed discharged from the
weighing hoppers 4 are fed into the corresponding collecting hoppers (7A7D) through
the corresponding collecting chutes (6A6D) to be temporarily accumulated therein.
Then, the objects to be weighed are discharged from the collecting hoppers (7A7D)
in a state of gathering together satisfactorily. Therefore, each discharge time
of the objects to be weighed discharged from the collecting hopper corresponding
to each discharge group can be shortened and the objects to be weighed can be also
prevented from being stuck inside the packaging machine.
Fig. 5 is a timing chart of the operation of the combination weigher in the case
where three discharge groups are determined in the above mentioned combination process.
Whereas one weighing cycle and discharge timings of the collecting hoppers in that
weighing cycle are illustrated in Fig. 5 as in Fig. 4, such operation is repeated
in succession. In Fig. 5, first, second and third discharge groups are first, second
and third discharge groups in the combination process, respectively. Alternatively,
numbers (1, 2, 3, ...) indicating discharge priority may be assigned to all base
groups (or collecting hoppers), and smallest numbers of the base groups belonging
to the first, second, and third discharge groups in the combination process may
be compared to each other, and the discharge group including the base group with
smallest number, the discharge group including the base group with the second smallest
number, and the discharge group including the base group with the third smallest
number may be determined as the first, second and third discharge groups, respectively.
As in the configuration of Fig. 4, one weighing cycle in the combination weigher
consists of the discharge time t1, the stabilization time t2, and the combination
time t3.
In the configuration of Fig. 5, the gate of the collecting
hopper corresponding to the first discharge group is opened to discharge the objects
to be weighed to the packaging machine in response to a feed command signal output
from the packaging machine at timing a, the gate of the collecting hopper corresponding
to the second discharge group is opened to discharge the objects to be weighed to
the packaging machine in response to a feed command signal output from the packaging
machine at timing b, and the gate of the collecting hopper corresponding to the
third discharge group is opened to discharge the objects to be weighed to the packaging
machine in response to a feed command signal output from the packaging machine at
timing c. By operating the discharge groups in a predetermined sequence with a difference
of T/3 time (T indicates time of one weighing cycle), the discharge can be performed
three times faster than in a case where the entire apparatus operates as a single
combination weigher, thereby allowing the combination weigher to be adapted to a
packaging machine operated at a high speed. Moreover, as in the configuration of
Fig. 4, the objects to be weighed discharged from the weighing hoppers 4 are temporarily
accumulated in the corresponding collecting hoppers and are discharged from the
collecting hoppers in a state of gathering together satisfactorily. Therefore, the
each discharge time of the objects to be weighed discharged from the collecting
hoppers corresponding to the respective discharge groups can be shortened and the
objects to be weighed can be also prevented from being stuck inside the packaging
machine.
In this embodiment, the number of collecting chutes and the collecting hoppers,
i.e., the number of base groups is required to be set to three or more, and is desirably
set to four or more. This is because when the number is four or more, the combination
group in the combination process can be formed by combining plural base groups,
and more combinations can be created for the combination calculation in step S3
when the weighing hoppers in the base groups is equal.
(Embodiment 2)
The configuration of the combination weigher of this embodiment
is identical to that of the first embodiment shown in, for example, Figs. 1(a) and
1(b), and will not be further described.
Then, the operation of the combination weigher of this embodiment will be described.
The significant distinction between the first and second embodiments is a method
of the combination process executed by the control unit 21.
Fig. 6 is a flowchart showing the operation of the combination weigher of this embodiment.
It is assumed that the number of discharging of the objects to be weighed in one
weighing cycle to the outside (e.g., packaging machine) is p (p is plural numbers).
The above mentioned combination process is steps S20 to S28. The control unit 21
contains a memory therein, and is configured to store in the memory required information
found in the combination process (information as to which base group weighing hoppers
form combination groups, discharge candidate groups and discharge groups, information
indicating the weighing hoppers forming optimal combination, information indicating
optimal combination weight, information indicating differences and total of differences
calculated in step S27, etc).
The repeat step S20 is to find all discharge candidate
group sets and to find a total of differences mentioned later for each discharge
group set by repeating the following steps S21 through S27.
First, in step S21, n is initialized to 1. n indicates
the number of discharge candidate groups found in step S23 mentioned later.
In step S22, an arbitrary combination group including a
combination of k base groups which do not belong to the determined discharge candidate
group in the repeat step S20 with the same ordinal number while the repeat step
S20 (S21 through S27) is repeated is found. Since there is no determined discharge
candidate group, one group including a combination of k base groups selected
from all base groups is one combination group.
In step S23, the combination calculation is performed based
on the measured values of the weighing hoppers 4 within the combination groups found
in step S22 to select weighing hoppers 4 forming combination (optimal combination)
in which a total measured value with respect to a target weight is in an allowable
range and a difference with the target weight is smallest, and to determine the
total measured value of the weighing hoppers 4 forming the optimal combination as
optimal combination weight. The base group including the weighing hoppers 4 forming
the optimal combination is determined as the nth discharge candidate group.
Then, in step S24, it is determined whether or not n is
equal to p 1, and if it is determined that n is not equal to p 1,
then one is added to n in step 25, and the process from the step S22 is repeated.
On the other hand, if it is determined that n is equal to p  1, the process
moves to step S26. That is, steps S22 and S23 are repeated until p  1 discharge
candidate groups are determined.
In step S26, the combination calculation is performed based
on the measured values of the weighing hoppers 4 within the base groups which do
not belong to the p  1 discharge candidate groups to select the weighing
hoppers 4 forming combination (optimal combination) in which a total measured value
with respect to the target weight is in the allowable range and a difference with
the target weight is smallest, and to determine the total measured value of the
weighing hoppers 4 forming the optimal combination as an optimal combination weight.
The base group including the weighing hoppers 4 forming the optimal combination
is determined as the pth discharge candidate group, and thus determined p discharge
candidate groups are determined as a discharge group set.
In step S27, with respect to each discharge candidate group
in the discharge candidate group set, a difference between the optimal combination
weight and the target weight is calculated, and further a total of the differences
found with respect to the discharge groups is calculated.
The steps S21 through S27 are repeated (step S20) to thereby
find all discharge candidate groups and a total of the differences are found with
respect to each discharge candidate group set.
Then, in step S28, one discharge candidate group set whose
difference total found in step S27 is smallest is selected from all discharge candidate
group sets, and the p discharge candidate groups in that discharge candidate group
set are determined as the discharge groups. Through the above mentioned steps S20
through S28, the p discharge groups are determined.
Then, in step S29, the gates of the weighing hoppers 4 forming the optimal combinations
in the p discharge groups are opened simultaneously to feed the objects to be weighed
to the corresponding collecting hoppers.
Then, in step S30, every time the feed command signal is
received from the packaging machine, the gate of the collecting hopper corresponding
to each discharge group is opened to discharge the objects to be weighed to the
packaging machine. In other words, every time the feed command signal is received
from the packaging machine, the objects to be weighed having the optimal combination
weight in each discharge group are discharged.
The difference between the optimal combination weight and the target weight with
respect to each discharge candidate group found in step S27 will be described. By
performing the combination calculation, the weighing hoppers 4 forming a combination
in which the total measured value of the weighing hoppers 4 with respect to the
target weight is in an allowable range and the difference with the target weight
is smallest are selected as the weighing hoppers 4 forming the optimal combination.
If the allowable range is more than the target weight, the difference may be obtained
by subtracting the target weight from the optimal combination weight. In a case
where a value smaller than the target weight is a lower limit value in the allowable
range and a value larger than the target weight is an upper limit value in the allowable
range, the difference may be obtained by subtracting the target weight from the
optimal combination weight as the above mentioned difference if the optimal combination
weight is larger than the target weight, and the difference may be obtained by subtracting
the optimal combination weight from the target weight if the optimal combination
weight is smaller than the target weight. In any case, an absolute value (zero or
positive number) of the value obtained by subtracting the target weight from the
optimal combination weight may be found as the difference.
A case where the above mentioned process, especially the combination process in
steps S20 through 28 are applied to the configuration of Figs. 1 (a) and 1(b) will
be described in detail. For example, it is assumed that each of the base groups
A to D includes six weighing hoppers 4, the combination group is formed by combining
two base groups (k = 2), and four weighing hoppers 4 are selected to form the optimal
combination, and the number of discharging of the objects to be weighed in one weighing
cycle is two (p = 2).
First, in step S21 within the repeat step S20, n is initialized
to 1.
In step S22, since there is no determined discharge candidate
group initially, two base groups selected from all the base groups A to D, for example,
the base groups A and B are combined to form one combination group.
In step S23, the combination calculation is performed for the combination group
including, for example, the base groups A and B to select four weighing hoppers
4 forming optimal combination and to determine a total measured value of the weighing
hoppers 4 forming that optimal combination weight as optimal combination weight.
And, the base group including the weighing hoppers 4 forming the optimal combination
is determined as a first discharge candidate group. In this example, since four
weighing hoppers 4 are selected to form the optimal combination and six weighing
hoppers 4 are provided in each base group, the weighing hoppers 4 forming the optimal
combination may belong to both or one of the base groups A and B. If the weighing
hoppers 4 forming the optimal combination belong to both of the base groups A and
B, then the base groups A and B are the discharge candidate groups. If the weighing
hoppers 4 belong only to the base group A, then only the base group A is the discharge
candidate group, whereas if the weighing hoppers 4 belong only to the base group
B, then only the base group B is the discharge candidate group.
Then, in step S24, it is determined whether or not n is equal to
p  1. In this example, n = 1, p = 2, and p  1 = 1.
Since it is determined that n is equal to p  1, the process moves
to step 26.
If the base groups A and B have been determined as the
discharge candidate group in step S23, in step S26, the combination calculation
is performed based on the measured values of the weighing hoppers 4 within the base
groups C and D which do not belong to the discharge candidate group to select four
weighing hoppers 4 forming optimal combination and to determine a total measured
value of the weighing hoppers 4 forming that optimal combination as optimal combination
weight. Then, the base group including the weighing hoppers 4 forming that optimal
combination is determined as a second discharge candidate group and thus determined
two discharge candidate groups are determined as the discharge candidate group set.
If the base group A has been determined as the discharge candidate group in step
S23, then the combination calculation is performed based on the measured values
of the weighing hoppers 4 in the three base groups B, C, and D which do not belong
to the discharge candidate group to select four weighing hoppers 4 forming optimal
combination and to determine a total measured value of the weighing hoppers 4 forming
that optimal combination as optimal combination weight. And, the base group including
the weighing hoppers 4 forming optimal combination is determined as the second discharge
candidate group, and thus determined two discharge candidate groups are determined
as a discharge candidate group set.
In step S27, with respect to each of the two discharge candidate groups in the discharge
candidate group set, the difference between the optimal combination weight and the
target weight is calculated and, further, a total of the differences found with
respect to the respective discharge candidate groups are calculated.
Furthermore, steps S21 through S27 of the repeat step S20
are repeated. For example, the above mentioned process is repeated in step S22 with
respect to a case where the base groups A and C are the combination group, and further
with respect to a case where the base groups A and D are the combination group.
In the same manner, the process is repeated with respect to cases where the base
groups B and C, the base groups B and D, and the base groups C and D are combination
groups, respectively. Thereby, all discharge candidate group sets are found and
the total of the differences with respect to each discharge group set is found.
Then, in step S28, one candidate discharge candidate group
set whose difference total found in step S27 is selected from all discharge candidate
group sets, and the two discharge candidate groups in that discharge candidate group
set are determined as the discharge groups.
Subsequently, the combination process in step S20 to S28 in a case where there are
seven base groups (seven collecting chutes and seven collecting hoppers) will be
described. Here it is assumed that each of the seven base groups A to G includes
four weighing hoppers 4, the combination group is formed by combining two base groups
(k = 2), four weighing hoppers 4 are selected as the weighing hoppers 4 forming
optimal combination, and the number of discharging of the objects to be weighed
in one weighing cycle is three (p = 3).
First of all, in step S21 of the first repeat step S20, n is initialized to 1.
In step S22, since there is no determined discharge candidate
group initially, two base groups selected from all the base groups A to G, for example,
the base groups A and B are combined to form one combination group.
In step S23, the combination calculation is performed for
the combination group including, for example, the base groups A and B to select
four weighing hoppers 4 forming the optimal combination and to determine the total
measured value of the weighing hoppers 4 forming that optimal combination weight
as the optimal combination weight. And, the base group including the weighing hoppers
4 forming the optimal combination is determined as a first discharge candidate group.
In this example, since four weighing hoppers 4 are provided in each base group,
the four weighing hoppers 4 selected to form the optimal combination may belong
to both or one of the base groups A and B forming the combination group.
Then, in step S24, it is determined whether or not the
n is equal to p 1. In this example, initially, n = 1,
p = 3, and p  1 = 2. Since it is determined that n is not equal to
p  1, n = 2 is set in step S25 and then the process return to step S22.
If the base groups A and B have been determined as the
discharge candidate group in step S23, in step S22, one of 10 ( = 5C2) combination
groups including two base groups selected from five base groups C to G, excluding
the base groups A and B is determined as the combination group. Also, if only one
base group (e.g., base group A) has been determined as the discharge candidate group,
then one combination group is selected from 15 ( = 6C2) combination groups including
two base groups selected from six base groups B to G, excluding the base group A.
Following this, step S23 is performed in the same manner
as described above to determine a second (n = 2) discharge candidate group.
Then in step S24, n = 2, p = 3, and p  1 = 2. Since it is
determined that n is equal to p  1, the process moves to step S26.
If the base group A has been determined as the first discharge candidate group and
the base groups B and C are determined as the second discharge candidate groups,
in step S26, the combination calculation is performed based on the measured values
of the weighing hoppers 4 within the base groups D to G which do not belong to the
discharge candidate groups to select the weighing hoppers 4 forming optimal combination
and to determine a total measured value of the weighing hoppers 4 forming that optimal
combination as optimal combination weight. And, the base groups including the weighing
hoppers 4 forming the optimal combination is determined as the third discharge candidate
group, and thus determined three discharge candidate groups are determined as a
discharge candidate group set.
In step S27, with respect to each of the three discharge
candidate groups in the discharge group set, a difference between the optimal combination
weight and the target weight is calculated, and further a total of the differences
found with respect to the discharge candidate groups is calculated.
Further, the steps S21 through S27 of the repeat step S20
are repeated. In this example, in step S21 of the second repeat step S20, n = 1
is set, in step S22, the base groups A and B identical to those of the first repeat
step S20 are determined as the combination group, and steps S23, S24, and 25 are
performed. Thereafter, in step S22 in the case of n = 2, a combination group
different from the combination group found in the first repeat step S20 (n = 2)
is found. For example, when the discharge candidate group found in step S23 is identical
to the combination group, in the first repeat step S20, the base groups A and B
are determined as the combination group in step S22 in the case of n = 1
and the base groups C and D are determined as the combination group in step S22
in the case of n = 2. And, in the second repeat step S20, the base groups
A and B are determined as the combination group in step S22 in the case of n = 1
and the base groups C and E are determined as the combination group in step S22
in the case of n = 2. And, in the third repeat step S20, the base groups A and B
are determined as the combination group in step S22 in the case of n = 1 and the
base groups C and F are determined as the combination group in step S22 in the case
of n = 2. And, in the fourth repeat step S20, the base groups A and B are determined
as the combination group in step S22 in the case of n = 1 and the base groups C
and G are determined as the combination group in step S22 in the case of n = 2.
Then, in the fifth to eighth repeat steps S20, the base groups A and C (fifth to
eight repeat steps S20) are determined as the combination group found in step S22
in the case of n = 1, and the base groups B and D (fifth step S20), the base groups
B and E (sixth step S20), the base groups B and F (seventh step S20) and the base
groups B and G (eighth step S20) are determined as the combination group in step
S22 in the case of n = 2. In this manner, by repeating the repeat step S20, all
discharge candidate group sets are found, and in addition, the total of the differences
is found with respect to each discharge candidate group set.
Then, in step S28, one discharge candidate group set whose total difference found
in step S27 is smallest is selected from all discharge candidate group sets, and
the three discharge candidate groups in that discharge candidate group set are determined
as the discharge groups.
Subsequently, a combination process in step S20 to S28 in a case where there are
three base groups (three collecting chutes and three collecting hoppers) will be
described. Here it is assumed that each of three base groups A to C includes eight
weighing hoppers 4, four weighing hoppers 4 are selected as the weighing hoppers
4 forming the optimal combination, and the number of discharging of the objects
to be weighed in one weighing cycle is twice (p = 2). When the number of base groups
is four or more, it is desirable to combine plural base groups to form a combination
group. However, when the number of base groups is three as in this example, each
combination group includes one base group (k = 1). In other words, the combination
group is identical to the base group.
First of all, in step S21 of the repeat step S20, n is
initialized to 1.
In step S22, since there is no determined discharge candidate
group initially, one of the base groups A, B, and C is the combination group.
In step S23, the combination calculation is performed for
the combination group found in step S22 to select the weighing hoppers 4 forming
the optimal combination and to determine the total measured value of the weighing
hoppers 4 forming optimal combination as optimal combination weight. And, the base
group (here, base group is identical to the combination group) including the weighing
hoppers 4 forming the optimal combination is determined as a first discharge candidate
group.
Then, in step S24, it is determined whether or not the n is equal to
p 1. In this example, n = 1, p = 2, and p 1 = 1. Since
it is determined that n is equal to p  1, the process moves to step
S26.
If the base group A has been selected as the combination
group in step S22 and the base group A has been determined as the discharge candidate
group in step S23, then, in step S26, the combination calculation is performed based
on the measured values of the weighing hoppers 4 within the base groups B and C
which do not belong to the discharge candidate group to select four weighing hoppers
4 forming optimal combination and to determine a total measured value of the weighing
hoppers 4 forming that optimal combination as optimal combination weight. Then,
the base group including the weighing hoppers 4 forming that optimal combination
is determined as a second discharge candidate group and thus determined two discharge
candidate groups are determined as a discharge candidate group set.
In step S27, with respect to each of the two discharge
candidate groups in the discharge candidate group set, a difference between the
optimal combination weight and the target weight is calculated, and further, a total
of the differences found with respect to the respective discharge candidate groups
is calculated.
Furthermore, the process of the steps S21 to S27 of the
repeat step S20 are repeated. For example, subsequently, the process is repeated
with respect to a case where the base group B is selected as the combination group
in step S22, and further, the process is repeated with respect to a case where the
base group C is selected as the combination group in step S22. Through these processes,
all discharge candidate group sets are found and the total of the differences is
found with respect to each discharge candidate group set.
Then, in step S28, one discharge candidate group set whose
difference total found in step S27 is smallest is selected from all discharge candidate
group sets, and two discharge candidate groups in that discharge candidate group
set are determined as the discharge group.
Whereas in the above mentioned process in Fig. 6, the base group including the weighing
hoppers 4 forming the optimal combination in the combination group is determined
as the discharge candidate group, the combination group may alternatively be directly
determined as the discharge candidate group (in this case, combination precision
may be slightly reduced). Also, whereas the combination calculation is performed
based on the measured values of the weighing hoppers 4 within the base groups which
do not belong to p  1 discharge candidate groups to determine the base group
including the weighing hoppers 4 forming the optimal combination as pth discharge
candidate group in step S26, base groups which do not belong to the p 1
discharge candidate groups may alternatively be determined as the pth discharge
candidate group (Note that the combination calculation is also performed in this
case). In these cases, in step S30, in the respective discharge groups for sequentially
discharging the objects to be weighed, only the collecting hoppers corresponding
to the base groups including the weighing hoppers 4 forming the optimal combination
within those discharge groups may be opened and closed to discharge the objects
to be weighed.
Whereas step S27 is performed within the repeat step S20,
the difference between the optimal combination weight and the target weight for
the respective discharge candidate groups may be found and the total of the differences
may be found with respect to each of all the discharge candidate group sets extracted
in the repeat step S20 before step S28 is performed after the repeat step S20 (repeating
of steps S21 to S26) is completed, instead of performing step S27 within the repeat
step S20.
Also, when the step S22 is repeated within one loop in which the repeat step S20
is repeated, the number k of the base groups forming the combination group may be
changed. For example, the number of base groups forming the combination groups may
be set larger in second step S2 than in first step S2.
In this embodiment, also, the timing chart of the operation of the combination weigher
in the case where the two discharge groups are determined by the combination process
is illustrated in Fig. 4, and the timing chart of the operation of the combination
weigher in the case where the three discharge groups are determined by the combination
process is illustrated in Fig. 5. The first, second, and (third) discharge groups
illustrated in Fig. 4 (Fig. 5) are the discharge groups comprising the first, second,
and (third) discharge candidate groups in the discharge candidate group set selected
in step S28 in the combination process. Alternatively, numbers (1, 2, 3, ...) indicating
discharge priority may be assigned to all base groups (or collecting hoppers), and
smallest numbers of the base groups belonging to the discharge groups determined
in step S28 may be compared to each other, and the discharge group including the
base group with smallest number, the discharge group including the base group with
the second smallest number, and the discharge group including the base group with
the third smallest number in the case of Fig. 5 may be determined as the first,
second, and third discharge groups, respectively.
In this embodiment, as in the first embodiment, as shown
in Figs. 4 and 5, the discharge can be performed twice or three times faster than
in a case where the entire apparatus operates as a single combination weigher, thereby
allowing the combination weigher to be adapted to a packaging machine operated at
a high speed. Moreover, the objects to be weighed discharged from the weighing hoppers
4 are fed into the corresponding collecting hoppers through the corresponding collecting
chutes to be temporarily accumulated therein and are discharged from the collecting
hoppers in a state of gathering together satisfactorily. Therefore, each discharge
time of the objects to be weighed discharged from the collecting hopper corresponding
to each discharge group can be shortened and the objects to be weighed can be also
prevented from being stuck inside the packaging machine.
In the combination process of this embodiment, the total
weight of the objects to be weighed which are discharged from the p discharge groups
can be reduced and thus consumption amount of the objects to be weighed can be reduced
as compared to the first embodiment.
In this embodiment, the number of collecting chutes and the collecting hoppers,
i.e., the number of base groups is required to be set to three or more, and is desirably
set to four or more. This is because when the number is four or more, the combination
group in the combination process can be formed by combining plural base groups,
and more combinations can be created for the combination calculation in step S23
when the number of the weighing hoppers in the base groups is equal.
In the first and second embodiments, the collecting chutes
and the collecting hoppers shown in Figs. 1(a) and 1(b) may be replaced by collecting
chutes and collecting hoppers shown in Figs. 7(a) and 7(b). Fig. 7(a) is a schematic
view showing the collecting chutes and the collecting hoppers which replace the
collecting chutes and the collecting hoppers shown in Figs. 1(a) and 1(b) as seen
from laterally, and Fig. 7(b) is a schematic view of the collecting chutes and the
collecting hoppers shown in Fig. 7(a) as viewed from above. Whereas the four collecting
hoppers 7A to 7D are provided integrally at a lower part of a center of the chute
61 of the substantially inverted conical shape as shown in Figs. 1(a) and 1(b),
outlets of the collecting chutes 6A to 6D are provided at the lower part in the
vicinity of the center of the chute 61 of substantially inverted conical shape to
be spaced apart from each other, collecting hoppers 7a to 7d are respectively provided
at the outlets, and a lower chute 63 of an inverted frustconical shape is provided
to receive the objects to be weighed which are discharged from the collecting hoppers
7a to 7d and to feed them to the tube 51 of the packaging machine. The gates of
the four collecting hoppers 7a to 7d may be constituted as in those of the known
feeding hoppers 3 and the like. The lower chute 63 may be omitted so long as the
objects to be weighed which are discharged from the collecting hoppers 7a to 7d
can be directly fed into the tube 51 of the packaging machine. In a further alternative,
a substantially inverted conical region of the side surface of the chute 61 may
be integral with the lower chute 63, and the collecting hopper may be provided at
an intermediate position of the chute integrally formed. As described above, the
number of collecting chutes and the collecting hoppers, i.e., the number of base
groups is required to be three or more.
The collecting chutes 6A to 6D may be separated. To be
specific, the collecting chutes may be separated to respectively correspond to the
base groups, the collecting hoppers (7a to 7d) may be provided at lower parts of
the collecting chutes, and the lower chute (63) may be provided to receive the objects
to be weighed which are discharged from all the collecting hoppers and to discharge
them to the tube (51) of the packaging machine.
Whereas in the first and second embodiments, the number of the weighing hoppers
4 which are included in each base group and participate in the combination is set
to equal, it is not necessarily set to equal. For example, eleven weighing hoppers
4 in total are equipped, and five base groups each including two weighing hoppers
4 and one base group including one weighing hopper 4 may be created.
Whereas in the first and second embodiments, only the weighing
hoppers 4 are illustrated as hoppers which participate in the combination, a memory
hopper 5 may be provided obliquely below each weighing hopper 4 as shown in Fig.
8 to participate in the combination. In this case, each weighing hopper 4 is capable
of selectively discharging the objects to be weighed to the collecting chute 6X
(6A to 6D) or the memory hopper 5. When the memory hopper 5 becomes empty, the weighing
hopper 4 feeds the objects into it. The control unit 21 performs the combination
process to determine discharge groups and select combination of hoppers which have
optimal combination weight from a plurality of weighing hoppers 4 and memory hoppers
5 in the respective discharge groups, so that hoppers forming that combination discharge
the objects to be weighed onto the collecting chute 6X. The weight of the objects
to be weighed that has been measured in the weighing hopper 4 located above the
memory hopper 5 is used as the weight of the objects to be weighed inside the memory
hopper 5 used in the combination calculation.
For example, in the construction of Figs. 1(a) and 1(b),
three weighing hoppers 4 and three memory hoppers 5 are needed in each of the base
groups A to D to achieve performance substantially equivalent to that of a combination
weigher equipped with, for example, six weighing hoppers 4 in each of the base groups
A to D. This makes it possible to decrease the weight sensors 41 which are expensive
to half in number.
Furthermore, as shown in Fig. 9, each memory hopper 5 may
be configured to include two accommodating chambers 5a and 5b. In this case, each
weighing hopper 4 is capable of selectively discharging the objects to be weighed
to the accommodating chamber 5a or the accommodating chamber 5b, and does not discharge
the objects to be weighed onto the collecting chute 6X. The two accommodating chambers
5a and 5b of each memory hopper 5 are capable of independently discharging the objects
to be weighed. The combination calculation is performed based on the weights of
the objects to be weighed inside the accommodating chambers 5a and 5b of each memory
hopper 5, and the accommodating chambers 5a and 5b participate in the combination,
but the weighing hoppers 4 do not participate in the combination. The weight of
the objects to be weighed that has been measured in the weighing hopper 4 located
above the accommodating chambers 5a and 5b is used as the weights of the objects
to be weighed inside the accommodating chambers 5a and 5b. The weighing hopper 4
may participate in the combination provided that each weighing hopper 4 and the
accommodating chamber 5a or 5b of the corresponding memory hopper 5 are simultaneously
selected. For example, when the weighing hopper 4 and the accommodating chamber
5 a of the memory hopper 5 are simultaneously selected, the objects to be weighed
are discharged from the weighing hopper 4 onto the collecting chute 6X through the
accommodating chamber 5a.
Moreover, as shown in Fig. 10, each weighing hopper 4 may
be configured to have two weighing chambers 4 and 4b. In this case, the feeding
hopper 3 is capable of selectively discharging the objects to be weighed to the
weighing chamber 4a or the weighing chamber 4b, and the two weighing chambers 4a
and 4b of the weighing hopper 4 are capable of independently discharging the objects
to be weighed. The combination calculation is performed based on the weights of
the objects to be weighed inside the weighing chambers 4a and 4b of each weighing
hopper 4 and the weighing chambers 4a and 4b participate in the combination. In
each weighing hopper 4 having the two weighing chambers 4a and 4b, when the objects
to be weighed are fed only to one of the weighing chambers, for example, the weighing
chamber 4a, the weight sensor 41 measures a weight of the objects to be weighed
inside the weighing chamber 4a. When the objects to be weighed are fed to the other
weighing chamber 4b, the weight sensor 41 measures a total weight of the objects
to be weighed inside the two weighing chambers 4a and 4b. The control unit 21 (see
Fig. 1) calculates the weight of the objects to be weighed inside the weighing chamber
4b by subtracting the weight of the objects to be weighed inside the weighing chamber
4a from the total weight of the objects to be weighed inside the two weighing chambers
4a and 4b, and performs combination calculation.
Moreover, as shown in Fig. 11, each weighing hopper 4 may
be configured to have two weighing chambers 4a and 4b, and the memory hopper 5 having
two accommodating chambers 5a and 5b corresponding to the weighing chambers 4a and
4b of the weighing hopper 4 may be provided below each weighing hopper 4. In this
case, each feeding hopper 3 is capable of selectively discharging the objects to
be weighed to the weighing chamber 4a or the weighing chamber 4b of the weighing
hopper 4. The objects to be weighed in the weighing chamber 4a of the weighing hopper
4 are fed into the accommodating chamber 5a of the memory hopper 5 and the objects
to be weighed in the weighing chamber 4b of the weighing hopper 4 are fed into the
accommodating chamber 5b of the memory hopper 5. The combination calculation is
performed based on the weights of the objects to be weighed inside the accommodating
chambers 5a and 5b of each memory hopper 5, the accommodating chambers 5a and 5b
participate in the combination, and the weighing hopper 4 does not participate in
the combination. The weights of the objects to be weighed that have been measured
and calculated in the weighing chambers 4a and 4b of the weighing hopper 4 located
above the accommodating chambers 5a and 5b are used as the weights of the objects
to be weighed inside the accommodating chambers 5a and 5b. The weighing chambers
4a and 4b of the weighing hopper 4 may participate in the combination provided that
the weighing chambers 4a and 4b and the corresponding accommodating chamber 5a and
5b are simultaneously selected. For example, when the weighing chamber 4a and the
corresponding accommodating chamber 5a are simultaneously selected, the objects
to be weighed are discharged from the weighing chamber 4a onto the collecting chute
6X through the accommodating chamber 5a.
The dispersion feeder 1, the linear feeders 2, and the
feeding hoppers 3 in the combination weighers of the first and second embodiments
are not intended to be limited in construction to the above. They may be constructed
in other ways depending on the type of the objects to be weighed such as powder
or chunks so long as means for feeding the objects to be weighed to the weighing
hopper 4 is equipped. Furthermore, the control unit 21 is not limited to being configured
as the single control apparatus, but instead may be configured to include a plurality
of control apparatuses disposed in a distributed manner, and these control apparatuses
may cooperate to control the operation of the combination weigher.
Numerous modifications and alternative embodiments of the invention will be apparent
to those skilled in the art in view of the foregoing description. Accordingly, the
description is to be construed as illustrative only, and is provided for the purpose
of teaching those skilled in the art the best mode of carrying out the invention.
The details of the structure and/or function may be varied substantially without
departing from the spirit of the invention and all modifications which come within
the scope of the appended claims are reserved.
Industrial Applicability
The combination weigher of the present invention is useful
as a combination weigher capable of being adapted to a packaging machine operated
at a high speed.