The present invention relates to the field of engraving methods and
devices and, particularly, to an automated apparatus and method for performing
Many single engraving applications have been hampered by the need
for and general lack of skilled engraving machine operators. Prior to 1980 and
the advent of computerised engraving machines this was even more pronounced because
many of the skills required to use a manual engraving machine involved manual dexterity.
Computerised engraving machines, such as those described in US Patent Nos. 4,437,150
, 4,439,834, and 4,561,814, each to Dahlgren, Jr. et al, eliminated or simplified
many of the thought processes associated with engraving. A number of these early
machines also simplified much of the material handling aspects of the trade as
From that time until now little has changed. For a wide variety of
applications the computerised engraving machine is still, by far, the best solution.
However, relatively skilled operators are still required to deal with many aspects
of the engraving process, such as material selection, cutting tool selection, layout
details, workpiece fixturing and cutting speeds and feeds. The present challenge
is to limit or eliminate the high skill levels usually associated with engraving
so that the process becomes practical for more and more businesses or users.
WO 93/20522 describes an engraving system in which a number of customer
or shop terminals can communicate through a telephone system with a display station
which, from a scanner, can transmit to the customer or shop terminals display data
relating to articles which can be engraved. The system includes an engraving station
which has control units for utilising signals, transmitted by the customer or shop
terminals, as engraving signals for controlling the engraving of an article located
in an engraving machine at the engraving station.
According to the present invention there is provided an automated
engraving system as defined hereinafter by claim 1, to which reference should now
A preferred embodiment of the invention provides a combination of
an automatic three axis engraving system and an automatic material handling system
and interfaces them with a user friendly font end software system thereby supplanting
the need for a skilled operator to produce an engraved workpiece.
The front end software system receives user-supplied selections of
indicia (i.e. the text, designs, pictures etc. to be engraved onto the workpiece)
and workpiece type, and a controller uses the user-supplied information to manage
the physical operation of the engraving system. The controller performs three general
functions: (1) workpiece handling, or the movement of a workpiece of the selected
type into an engraving location and dispensing the workpiece to the user following
engraving; (2) X-, Y-, and Z-axis engraving tool movement, which includes movement
of the engraving tool as needed to engrave the text or other indicia onto the workpiece
(by X- and Y- axis movement) and adjustment of engraving tool pressure on the workpiece
(Z-axis adjustment); and (3) accessory dispensing, which is the selection and dispensing
of an accessory corresponding to the selected workpiece.
The workpiece handling system is preferably a stepper motor driven
system which moves the workpiece from a self actuated delivery location, transports
it to an engraving location where it is automatically clamped in place, and then
releases the workpiece into an exit chute after engraving is complete. Workpieces
are stacked vertically and stored in a plurality of columns, with each column storing
a different type of workpiece.
Each column is equipped with a spring-driven positive feed mechanism
which pushes the stack of workpieces vertically upwards such that the top workpiece
in the stack is pushed into a relief formed in the bottom surface of a clamping/transport
plate. The relief is shaped, within close tolerances, to match the shape of the
workpiece. Uniform workpiece movement within the columns is assured by maintaining
the spring within a substantially linear operating range and preventing the spring
At the start of the engraving operation, the clamping/transport plate
corresponding to the selected workpiece is engaged by the workpiece handling system
and advanced until the workpiece captured in its relief is positioned over upwardly
biased rollers. The rollers positively clamp the workpiece inside the relief and
also facilitate travel of the clamping/transport plate.
A cutout is formed in the top of the clamping/transport device which
provides a window through which the engraving tool may engrave the workpiece.
After the workpiece is engraved, the workpiece handling system advances the clamping/transport
plate to a dispensing location, wherein the workpiece drops from the relief in
the clamping/transport plate and into a dispensing chute.
A stepper motor driven, three axis engraving unit is moveable between
the engraving locations associated with each column. The engraving unit is preferably
provided with a spring loaded diamond top for drag (or scratch) engraving of materials.
Stroke width, which is determined by diamond geometry, may be adjusted by varying
the amount of Z-axis pressure exerted on the tool. The pressure on the diamond
tip is variable and can be pre-programmed in the system, thus allowing for uniform
engraving results over a range of materials and thicknesses. Adjustments to tip
pressure are preferably carried out by raising or lowering the tip height using
a Z-axis stepper motor. This engraving unit design is also compatible with air
driven rotary spindles and direct drive rotary spindles.
The workpiece remains motionless during the engraving process while
the cutting tool moves in combinations of linear, step sequences along the X and
Y axes, respectively, thereby effectively producing both linear and arcing motion
as needed to engrave the various characters of the text. Computerised engraving
using stepper-driven X- and Y- axis movement is described in U.S. Patent No. 4,437,150.
In the preferred embodiment, Y-axis motion of the engraving tool is
achieved by means of a stepper driven Y-axis carriage which supports the engraving
tool. The Y-axis carriage is itself mounted to an X-axis carriage assembly which
travels along a bridge extending along the X-axis. This dual carriage system facilitates
increased engraving speed, as compared with existing computerised engraving systems,
by allowing for engraving tool movement in the Y direction. Existing devices require
movement of the actual workpiece in the Y axis direction and thus have slower
engraving speeds because of the relatively high total mass in motion.
A "place and pick" accessory dispenser is provided which is instructed
by the controller to dispense an accessory (e.g. luggage tag strap, pet tag hook,
medical tag bracelet) which corresponds to the chosen workpiece. Accessories are
stored in a plurality of vertical column, each of which stores a different accessory
Accessory dispensing is carried out by a picker arm which, when positioned
beneath the column holding the appropriate accessory, rotates through a slot in
the column to eject an accessory package through a second slot in the column side
and into a dispensing chute. The dispensing operation is accomplished by two stepper
motors: a "place" motor which moves the picker arm into alignment with the appropriate
column; and a "picker" motor which rotates the picker arm after it is placed in
proper picking position by the "place" motor.
Brief Description of the Drawings
Detailed Description of the Preferred Embodiment
- Fig. 1A is a simplified schematic representation of an automated vending unit
according to the present invention, showing the components mounted in a vending
- Fig. 1B is a front view of the workpiece dispensing unit of the vending unit
of Fig. 1A.
- Fig. 2 is a perspective view of an engraving unit and a workpiece positioning
unit of the vending unit of Fig. 1A.
- Fig. 3A is a side view of the workpiece positioning unit of the vending unit
of Fig. 1A engaged with a clamping plate associated with a workpiece delivery
- Fig. 3B is partial side section view of an anvil of the workpiece positioning
unit of Fig. 2.
- Fig. 3C is a front view of a workpiece column.
- Fig. 3D is an exploded view of an anvil, with the clamping plate guides not
- Fig. 3E is a partial top view of the workpiece columns.
- Fig. 3F is a perspective view of an extrusion from a workpiece column as it
appears when the column walls and plates are in place.
- Fig. 4 is a perspective view showing a portion of a carriage, the workpiece
positioning unit mounted to it, and a pair of clamping plates.
- Fig. 5A is a top view of an anvil and a clamping plate.
- Fig. 5B-5E are cross-sectional side views of the anvil and clamping plate taken
along the plane designated 5B-5B in Fig. 5A. The alignment of cut out in the clamping
plate relative to the through hole in the anvil for the workpiece delivery, workpiece
engraving and workpiece receiving positions respectively.
- Fig. 6 is a side view of the carriage, engraving unit, and workpiece positioning
unit, showing the X-axis bridge in cross-section.
- Fig. 7 is a front view of the engraving unit of the present invention.
- Figs. 8A and 8B are top and bottom views, respectively of the Y-axis carriage
of the present invention.
- Fig. 9 is a side view of the engraving unit according to the present invention.
- Fig. 10 is a perspective view of an accessory dispensing unit according to
the present invention, showing the dispensing unit as viewed from the front.
- Fig. 11 is a perspective view of the accessory dispensing unit of Fig. 9 showing
the dispensing unit as viewed from the back.
- Fig. 12 is a side view of the place and pick components of the accessory dispensing
- Fig. 13 is a front view of the place and pick components of the accessory dispensing
- Fig. 14 is a rear view of the place and pick components of the accessory dispensing
- Fig. 15 is a simplified block diagram showing the system of the present invention.
- Fig. 16 is a simplified flow diagram showing the functions of the front end
computer of the present invention.
- Fig. 17 is a simplified flow diagram showing the functions of the controller
in workpiece selection and dispensing.
- Fig. 18 is a simplified flow diagram showing the functions of the controller
in accessory dispensing.
- Fig. 19 is a simplified flow diagram showing the functions of the controller
in the managing of the engraving operation.
The engraving machine of the present invention is comprised generally
of a user interface device 10, which prompts for and receives engraving instructions
from a user, and a controller (not shown) which manages the engraving functions
and the dispensing of accessories.
Controlled by the controller are an engraving unit 12, a workpiece
positioning unit 14 (see Figs. 3 and 4) which receives workpieces from a workpiece
delivery system 16, and a pair of accessory dispensing units 18. As will be discussed
in detail, the controller provides drive signals to stepper motors that drive the
workpiece delivery, engraving, and accessory dispensing functions. Conventional
drivers (micro-stepping for the X-axis and Y-axis control and half-stepping for
the workpiece handling, accessory dispensing, and Z-axis control) may be used in
connection with the present invention. One such controller, including its use in
connection with stepper motors, is described in U.S. Patent No. 4,437,150. In the
preferred embodiment, the Dahlgren Control Systems Part No. 39-89028 micro-stepping
driver and the Dahlgren Control Systems Part No. R60-0001 half-stepping driver
The user interface device 10 is preferably a personal computer ("PC")
having a video monitor 24 which prompts the user to select a workpiece type (e.g.,
luggage tag, medical tag, key ring, or pet tag), and the text to be printed on
the desired workpiece. A conventional video touch screen 26 overlays the video
monitor 24 and is interfaced with the personal computer. The personal computer
prompts for and receives the user information necessary to begin a job, and also
may receive and process payment information. For example, a credit card reader,
a modem for use in verifying credit information, and a receipt printer may be interfaced
with and controlled by the personal computer. As will be described below, the user
input from the user interface device 10 is passed to the controller 20, processed,
and used by the controller in retrieving the relevant engraving format and engraving
tool pressure from its memory, managing the workpiece retrieval and engraving operations,
and dispensing the appropriate accessory (i.e. luggage tag strap, medical tag bracelet,
etc.) to be dispensed along with the engraved workpiece after engraving is complete.
To facilitate an understanding of these features, reference will be made to X-,
Y-, and Z-axes, each of which is designated in Fig. 2.
In the preferred embodiment, each component of the engraving system
is incorporated into a vending machine style housing 22.
Workpiece Delivery and Handling Units
Referring to Figs. 2-5, the workpiece delivery unit 16 of the present
invention is configured to offer the user a variety of workpiece types from which
to choose from. The workpiece delivery unit 16 provides a number of positive feed
columns 28 which use spring pressure to feed workpieces into a position from which
they can be retrieved by the workpiece handling unit 14 (Fig. 4) and carried to
an engraving location.
A number of workpiece columns 28 are provided, each corresponding
to one of the workpiece types offered to the user. Referring to Figs. 3A and 3C,
each workpiece column 28 is preferably one or more elongate extrusions 29a, 29b
of precision-machined material, such as aluminum, each having a throughbore 30a,
30b in the shape of the workpiece which is contained in the workpiece column. Stored
in each column 28 is a stack 31 of workpieces (Fig. 3A).
Coupled to each workpiece column 28, and contiguous with the throughbores
30a, 30b in each column, is a hollow, cylindrical tube 44 (Figs. 1A and 3A). In
the preferred embodiment, the workpiece column 28 and the cylindrical tube 44 are
proportioned such that approximately 150 to 300 workpieces, depending on workpiece
mass, may be stored in each column. The large capacity of the columns allows many
engraving operations to be performed before restocking of workpieces is needed.
Referring to Fig. 3A, disposed within each tube 44 is a spring 42
which provides the feeding force to push the stack 31 of workpieces upwardly through
the extrusions 29a, 29b and that therefore pushes the topmost workpiece (not shown)
of each column into a relief formed in a corresponding clamping plate 46 (Fig.
3B). The clamping plate 46 is preferably precision-machined and, as detailed below,
it is the structure that holds the workpiece in place during engraving.
Each spring 42 should be individually sized to accommodate the shape,
mass and quantity of the workpieces in its respective column. Proper functioning
of the workpiece delivery unit 16 involves use of a matured spring operating within
±30% of its overall operating length. In other words, spring length is chosen such
that the spring is compressed to no less than 30% of its mature length when the
column is full of workpieces and such that the spring is at no greater than 70%
of its mature length when the column is empty. Maintaining this operating range
insures a substantially linear spring force, within the limits of the spring. Consequently,
proportionally greater spring force is obtained when the column is full verses
nearly empty. This keeps the upward pressure of the workpiece at the clamping plate
46 within an acceptable range over the entire delivery range of the column 28.
A mature spring is obtained by placing a new spring under compression for approximately
The springs 42 are managed inside the columns 28 to insure they do
not bind. This is achieved by guiding the springs and by encouraging them to rotate
as they expand and compress. Without this, there is a tendency to bind and affect
In the preferred embodiment, two steps are taken to prevent binding
of the springs 42. First, a rod 15 (Fig. 3A) is disposed within each spring 42
and is held in place by a cap 17 resting on the upper end 19 of the spring. The
rod 15 helps prevent the spring 42 from bowing, which in turn prevents the spring
from binding against the inside walls of the extrusions 29a, 29b. Second, the spring
is left unsecured within the tube 44 and can therefore freely rotate.
At the top of each column 28 is an anvil 32 (Figs. 2, 3C and 3D)
which is preferably precision machined. Each anvil is connected to its neighboring
anvils by joining plates 34, which help to optimize the rigidity of the overall
system. Each anvil has a hole 36 in the shape of the related workpiece (Fig. 5B).
The hole 36 is chamfered at the top side 38 of the anvil to facilitate movement
and greater tolerance of the workpiece. On the bottom side of the anvil, the hole
36 matches up to the throughbore 30a of its respective upper extruded column 29a.
The holes 36 in the anvils 32 are machined to tighter tolerances than
are the throughbores 30 in their corresponding extrusions so as to guide workpieces
into the corresponding clamping plates 46. Preferably, the inside diameter of the
extrusion throughbores 30a, 30b is nominally 0.051mm (.020 inches) larger than
its respective anvil hole 36. In addition to the chamfer, the anvil hole has a
5° top to bottom relief angle on its inside diameter. Consequently, the extruded
column and the anvil provide for an economical yet precise feeding mechanism.
Four stationary guides 48 are fixed to the top of each anvil. The
guides 48 are preferably made of nylon, turcite, or teflon and each is individually
adjustable. Each guide 48 has a notch 52 along its circumference to accommodate
the clamping plate 46 as it moves from the receiving, to the engraving, to the
dispensing positions. (See Fig. 7)
Embedded in each anvil 32, at the engraving position of the workpiece,
is one or more elongate rollers 56 (see Fig. 3D). Each roller 56 is mounted for
rotation about its elongate axis. The rollers are spring biased in a direction
normal to the top surface 38 of the anvil.
As illustrated in Figs. 2, 3C and 4, 5A-5E corresponding to each anvil
32 is a clamping plate 46 which is slidable within the notches 52 in the guides
48. Since each guide 48 is adjustable, the centering and squareness of the clamping
plate 46 relative to the column 28 and the engraving position may be fine-tuned.
The clamping plate 46 is an elongate rectangular member which has a relief 54 formed
in its underside, near its distal end. (See Fig. 3B) Preferably, the relief 54
is in the shape of the corresponding workpiece. The relief is oversized to the
workpiece preferably by a nominal 0.089mm (.0035 inches) all around the sidewalls
of the relief looking at the bottom of the clamps, preferably having relief angles
themselves of 7° down to a depth of 0.81mm (.032 inch) (based on a nominal 1mm
(.040 inch) workpiece). The relief depth is nominally sized to the workpiece thickness,
in this case 1mm (.040 inches). The design allows for tolerances of up to 0.064mm
(± .0025 inches) through the use of leading and trailing edge chamfers in the
Centered around the relief is a cutout 55 in the shape of the workpiece.
During engraving, the cutout 55 provides access to the workpiece by the engraving
tool while relief 54 keeps the workpiece secure beneath the clamping plate 46.
The relative diameters of the cutout 55 and relief 54 are shown in
Fig. SE. The outer diameter of the relief tapers from a first diameter, designated
d3, to a second diameter designated d2. The inner diameter d1 of the cutout 55
is smaller than the second diameter d2 of the relief such that a shoulder is formed
between them. The workpiece is in abutment with this shoulder when it is captured
within the relief 54.
The clamping plate 46 is preferably plated to minimize wear and contamination
in the slide and bearing areas.
Attached to the proximal end 60 of the clamping plate is a receiving
component 62 which has a chamfered slot 64 formed in its underside. (See Fig.
In the material receiving stage (Fig. 5D), the upward spring force
from the workpiece delivery system 16 causes the topmost workpiece in each workpiece
stack 31 to pass through the through hole 36 in the anvil and to rest in the relief
54 in the corresponding clamping plate 46. During the material positioning phase
(Fig. 5C), the clamping plate 46 (and the workpiece situated within its relief)
is slidably advanced over the top surface of the anvil, between the guides 48,
until the workpiece rests on the rollers 56 as shown in Fig. 3B. This is the engraving
location, wherein the rollers are immediately beneath the workpiece (designated
500 in Fig. 3B, and 55B in Fig. 5A) and thereby provide upward pressure which holds
the workpiece in place during engraving. Because the cutout 55 is slightly smaller
than the workpiece, the workpiece cannot pass through the cutout but instead remains
captured beneath the clamping plate 46.
From Figs. 3A and 4 it can be seen that the workpiece handling unit
14 includes a stepper motor 66 mounted to a carriage 80 and coupled to a leadscrew
68. A limit switch 76 is mounted to the carriage 80 near the proximal end of the
leadscrew 68. Fastened to the leadscrew is a self-adjusting leadscrew nut 70.
The leadscrew nut 70 is attached to a workpiece selector block 72
which has a chamfered slot 74. A pair of throughbores 75 (Fig. 4) pass through
the workpiece selector block 72. Rods 77 are slidably received in each throughbore
75. A triggering plate 78 (Fig. 3A) is fixed to the workpiece selector block 72
so as to close the limit switch when the workpiece selector block 72 reaches the
proximal end of its travel.
Activation of stepper motor 66 results in rotary motion of the leadscrew
68 and corresponding linear movement of the leadscrew nut 70 and the workpiece
selector block 72 attached thereto. The selector block 72 slides over rods 77,
which help to maintain stability of the workpiece positioning unit during movement
of the selector block 72.
When selector block 72 is engaged with a receiving component 62 as
shown in Fig. 3A, linear movement of the workpiece selector block 72 along the
leadscrew 68 results in linear movement of the receiving component 62 and its associated
clamping plate 46. In this fashion, the workpiece handling unit 14 moves the clamping
plate between three positions. Each of the three positions is predetermined and
is arrived at by stepping the stepper motor through a predetermined number of incremental
steps in the desired direction.
The first position is the workpiece retrieval position (Fig. 2 &
Fig. 5D), in which the clamping plate 46 is positioned such that the relief 54
in the clamping plate is aligned with the hole 36 in the anvil 32. When the clamping
plate is in the workpiece retrieval position, the top workpiece in the associated
column becomes captured in the relief 54 due to the upward force of the spring
The second clamping plate position is the engraving position (Figs.
3A, 3B and 5C), in which the clamping plate is moved away from the carriage 80
such that the workpiece captured by the clamping plate 46 is resting on anvil rollers
56. The third position is the dispensing position (Fig. 5B), in which the clamping
plate 46 is advanced still further from the carriage 80 (not shown in Fig. 3C)
such that the relief 54 is away from the anvil and such that the workpiece can
drop from the relief into a dispensing chute (designated 230 in Fig. 11). For purposes
of comparison, Fig. 5A shows the location of the cut out 55 and relief 54 in the
material receiving position (designated 55a) and the material engraving position
(designated 55b) in dotted lines.
After an engraving operation is completed, the clamping plate 46
returns to the material receiving position such that its receiving component 62
is aligned with the receiving components 62 of all the other clamping plates.
Proper functioning of the engraving unit requires that the extruded
columns 28 and the anvils 32 be precisely aligned with each other and with the
clamping plate 46. Rigidity of alignment of these components is achieved using
a number of supports. Referring to Figs. 3C through 3E, it can be seen that each
anvil 32 is secured to its adjacent anvils by joining plates 34. The joining plates
34 are positioned in slots 33 formed in the adjacent sides of the anvils, such
that each joining plate 34 is disposed within two slots, one in each of two adjacent
Each joining plate 34 is provided with a pair of bores 35 (Fig. 3D).
The bores 35 are aligned with second bores 37 formed in elongate vertical supports
41. A bolt 39 is passed through each joining plate 34 at bore 35 and throughbore
37 in the corresponding vertical support member 41. As bolt 39 is tightened, joining
plate 34 clamps its associated anvils 32 to the elongate vertical support.
Referring to Fig. 3E, each vertical support member 41 has a first
slot 43 which receives a dividing wall 45 that separates each column 28. Second
slots 47, also formed in vertical support members 41 receive panels 49 which comprise
the back wall of the workpiece dispensing unit. Slots 47a receive panels 49a to
form a front wall on the workpiece dispensing unit. The dividing walls 45 and panels
49, 49a therefore bound the extrusion 29a, 29b on four sides and are in abutment
with the corresponding four sides of the plates 57a, 57b attached to the ends of
the extrusions 29a, 29b. These panels thus hold the extrusion 29a, 29b in place
by virtue of the precision machined relationship between the plates 57a, 57b and
the walls 45 and panels 49, 49a.
Referring to Fig. 1B rigidity of the overall workpiece delivery unit
16 is provided by a pair of precision machined steel side supports 51 which are
held together by a rear support and alignment bar 53, which is also preferably
precision-machined. Column base support 67, which is also connected between the
steel side supports 51, supports the aluminum extrusions 29a, 29b and the vertical
support members 41. Referring to Fig. 3C, each column may be provided with more
than one aluminum extrusion 29 in order to facilitate loading of workpieces during
maintenance of the engraving unit. Each aluminum extrusion 29 has end plates 57a,
57b bolted to each end. Each end plate 57a, 57b has a cut-out (not shown) in the
shape of the associated workpiece and aligned with the throughbore 30a, 30b. Slots
59 (see Fig. 3A) in each end plate provide a port through which an L-shaped tool
61 may be inserted during maintenance to retain spring 42 in a particular compressed
When a column 28 is running low on workpieces, the spring 42 will
be expanded above the end plates 57 of the lower aluminum extrusion 29 shown in
Fig. 3A. To re-stock the workpieces, a rod (not shown) can be inserted through
the hole in the anvil 32, and through the throughbore 30a in the upper aluminum
extrusion 29a until the spring 42 and any remaining workpieces are depressed below
the end plate 57a at the bottom end of the upper aluminum extrusion 29a. The L-shaped
tool 61 may then be inserted between the plates 57a, 57b and the rod removed from
the throughbore 30a. Once the spring 42 is contained in this way, workpieces may
be added to the upper aluminum extrusion 29a. After loading, the L-shaped tool
61 is removed from the column 28 and the spring allowed to expand.
The columns 28 are designed for easy interchangeability. The type
of workpiece stored in any column can be changed simply by substituting extrusions
and anvils. Moreover, a single large extrusion may be easily substituted for two
extrusions of the standard size in order to accommodate a large workpiece type.
Consequently, machines can be reconfigured in the field by low skilled service
The workpiece handling unit 14 is fixed to carriage 80, which also
supports the engraving unit 12, and which transports the workpiece handling unit
14 and the engraving unit 12 along the X-axis.
Referring to Figs. 2 and 6, X-axis travel occurs along a bridge 82,
which is preferably precision machined from extruded aluminum. The bridge 82 has
a substantially symmetrical cross-section, including a pair of upper flanges 84
and a pair of shorter, lower flanges 86. A web 88 connects the upper and lower
flanges on one side of the bridge to those on the opposite side. Connected to each
lower flange 86 is an elongate v-rail 90 which extends along the lower flange 86,
parallel to the X-axis. These v-rails, which are preferably precision-machined,
increase the stability of the bridge and they also provide a track which facilitates
An X-axis leadscrew 92 extends along the X-axis, just below the web
88 of the bridge 82. An X-axis stepper motor 94 (Fig. 2) is coupled to one end
of the X-axis leadscrew 92, such that activation of the motor 94 produces rotation
of the X-axis leadscrew 92.
The carriage 80 is formed in two tiers, one which extends above the
bridge 82 and one which extends below it. The carriage 80 is comprised of a pair
of columns 96 having a plate 98 extending between them. Extending normally of the
plate 98, below the bridge 82, is shelf member 100. Shelf member 100 is a rectangular
plate having a distal end, designated 102, and a proximal end, designated 104.
Mounted to the shelf member 100 is mount 120 which supports X-axis
leadscrew nut 122. The X-axis leadscrew nut is preferably a spring-loaded, adjustable,
self-adjusting leadscrew nut. Also mounted to the shelf member 100 are a pair of
v-wheels 124 mounted for rotation about their respective axes. Each v-wheel 124
has a "V" shaped groove 126 along its perimeter. The grooves are proportioned to
allow the v-wheels 124 to roll along the v-rails 90 mounted to the bridge 82. When
the X-axis stepper motor 94 is activated to rotate X-axis leadscrew 92, X-axis
leadscrew nut 122 causes the carriage 80 to travel along leadscrew 92, with v-wheels
124 rolling along v-rails 90.
X-axis travel serves two functions. Its first function is to position
the carriage 80 in alignment with the column 28 that contains the workpiece type
selected by the user. Prior to an engraving operation, all clamping plates 46
are in their first position, with each receiving component 62 of each clamping
plate 46 aligned along an axis parallel to the X-axis with all of the other receiving
components 62. As the carriage 80 carries workpiece selector block 72 in the X-direction,
slot 74 of the workpiece selector block 72 passes over tab 63 of each receiving
component 62. Rotating the X-axis stepper motor 94 through a predetermined number
of incremental steps in the desired direction positions slot 74 of workpiece selector
block 72 into engagement with tab 63 of the receiving component 62 associated with
the selected workpiece column. Activation of the workpiece positioning stepper
motor 62 at this point causes movement of clamp 46 and hence movement of the workpiece
into the engraving and dispensing positions as described above.
The second function of X-axis travel is to move the engraving tool
in the X-direction as needed to engrave the desired text. This X-axis movement
is also step-controlled and, because fine movement of the engraving tool is needed,
a micro-stepping driver is used in connection with the X-axis motor.
Engraving requires movement of the engraving tool in both the X- and
Y- directions. The components used for effecting Y-axis movement will next be
In Fig. 6, the tier of the carriage 80 located above the bridge 82
facilitates Y-axis travel of the engraving unit. Extending normally of the distal
end 102 of shelf member 100 are a pair of vertical support members 106 (see also
Fig. 7), and extending normally of proximal end 104 of the shelf member 100 are
a second pair of vertical support members 108. As shown in Fig. 2, each support
member 108 is secured to one of the columns 96. Extending cantilever-style from
each of the vertical supports 108, above the bridge 82, is a beam member 110. The
beam members are parallel to each other in the X-axis direction and are also parallel
to the shelf member 100 in the Z-direction.
Beam members 110 are supported by vertical support members 106, but
the beam members 110 extend beyond support members 106 in the Y-direction. Member
114 bridges the distal ends of beam members 110, such that a rectangular frame
is formed by plate 98, beam members 110 and member 114.
Elongate v-rails 116 line beam members 110 at the inside of the rectangular
frame. A Y-axis carriage 118 travels along these rails during Y-axis motion of
the engraving tool.
A Y-axis leadscrew 130 extends through plate 98 of carriage 80 and
couples with Y-axis stepper motor 132. The Y-axis carriage 118 is coupled to leadscrew
130 by means of an adjustable, self-adjusting leadscrew nut 136 (Fig. 8B) that
is preferably made of turcite.
Referring to Figs. 2 and 6-8, the Y-axis carriage 118 is a rectangular
carriage having a pair of long sides 138, a proximal end 140 which is coupled
to the leadscrew nut 136, and a distal end 142. V-shaped grooves 144 (Fig. 7) are
formed in the long-sides 138 of the carriage 118. As shown in Fig. 8B, four v-wheels
146 are mounted to the underside of the Y-axis carriage 118. Like the X-axis v-wheels
124, each Y-axis v-wheel 146 has a groove formed along its perimeter.
These v-wheels 146 are mounted to the carriage 118 such that their
grooves are substantially contiguous with the v-grooves 144 in the carriage 134.
The wheels 146 roll along v-rails 116 (Fig. 2) during Y-axis movement of the carriage
118, with the v-rails 116 extending into the grooves in the v-wheels and also into
the v-grooves 144 in the carriage 118. The v-rail and v-wheel design is preferred
over a rounded or flat rail design because it optimizes contact between the wheel
and the rail.
Y-axis travel is step controlled using a micro-stepping driver. The
Y-axis carriage preferably returns to a home location and resets the counting
sequence by means of a limit switch (not shown) in order to prevent error due to
cumulative step loss. Step errors are also avoided in the preferred embodiment
by constructing the carriage 80 and the carriage 118 using precision-machined components.
As shown in Fig. 8B, a bore 148 passes through the Y-axis carriage
118 in the Z-direction. Secured within bore 148 is engraving tool shaft 150 (Figs.
7 and 9) which itself has a throughbore (not shown) extending its longitudinal
length. An engraving tool 152, which supports the diamond tip 154 used for engraving,
is slidably received in the throughbore in the shaft 150. The engraving tool holder
is vertically biased with respect to the shaft 150 by a spring (not shown). Mounted
to the Y-axis carriage 118 is a mounting device 162 which supports Z-axis stepper
motor 164. Mounting device 162 is comprised of a plate 166 extending normally of
Y-axis carriage 118 and motor platform 168 which is substantially perpendicular
to plate 166 and parallel to Y-axis carriage 134. A pair of rods 163 (Fig. 7) extend
from the motor platform 168 in the Z-direction and are slidably received in a pair
of bores 165 formed in a brass holder 158.
Plate 166 has a slot 170 for receiving a proximal portion of brass
holder 158. Proximalmost portion 172 of brass holder 158 passes through the slot
170 and serves as a trip for Z-axis limit switch 174 which is connected to mounting
A Z-axis leadscrew 176 is coupled to Z-axis stepper 164 and extends
through motor platform 168. The end of the leadscrew 176 opposite the stepper
164 is unsecured to eliminate vibration and wear. Z-axis leadscrew nut 178 which
may be non-adjustable and which is preferably made from turcite, is mounted to
brass holder 158 and receives the Z-axis leadscrew 176. The leadscrew 176 is solid-coupled
by coupling 180 to the Z-axis stepper motor 164.
Activation of Z-axis stepper motor 164 results in linear upward or
downward motion (depending on the direction of rotation produced by the motor)
of the brass holder 158 by virtue of the leadscrew nut 178. As the brass holder
moves, it slides along rods 163 that are disposed within its bores 165. These rods
163 help to maintain the stability of the engraving tool.
Upward or downward movement of the brass holder 158 causes resultant
upward or downward movement of the diamond tip holder 152 against the biasing spring
and corresponding Z-axis movement of the diamond tip 154. The distance by which
the diamond tip is moved is determined by the number of step increments traveled
by the stepper motor, which is driven by a half-stepping driver (not shown). After
an engraving job is complete, the engraving tool is returned to a Z-axis home position,
thus triggering the limit switch 174 to reset the step counter.
Z-axis movement serves two purposes: it moves the diamond tip onto
and off of the workpiece during the engraving process (e.g. to begin engraving
or to lift the diamond tip when moving from one character in a word to the next);
it also provides a means for adjusting the width of the strokes made on the workpiece
during engraving. Thicker strokes are formed when relatively high pressure is applied
to the diamond tip, while thin strokes require relatively light pressure on the
By spring loading the diamond tip and using a stepper driven Z-axis
positioning system, the amount of diamond tip pressure can be varied within the
limits of the selected spring. Spring selection becomes a function of the material
selected for the workpieces to be engraved by this machine. Generally it is envisioned
that any material which is amenable to diamond engraving can be engraved using
the initial spring selection and some combination of pre-set spring compression
(affecting the lightest setting) and Z axis stroke (affecting the strongest setting).
The spring in this case is 5.08cm (2.0 inches) in overall length with a spring
rate of 36.03N (8.1 pounds) and a wire diameter of 1.07mm (.042 inches). The outside
diameter of the spring is 10.7mm (.420 inches) and the solid height is 1.42cm (.558
inches). These characteristics provide for operating motion within an acceptable
range of the spring allowing as close to linear change in force with compression
The design described above, coupled with the system software and
diamond tip selection, allows each job to be programmed for specific output characteristics.
In particular, diamond tip geometry, spring pressure and material hardness combine
to affect actual engraved stroke width. Consequently, when jobs are laid out and
material and diamond tip geometry selected, the particular stroke width can be
adjusted within the job by varying Z axis position. The significance of this is
that each column may have a different workpiece, each having its own font styles
and stroke widths and thus its own style or look.
Accessory Dispensing Unit
As shown in Fig. 1, the preferred embodiment has two identical accessory
dispensing units 18 mounted in the engraving booth. These units operate using combined
concepts of gravity feed and positive dispensing using a pair of stepper motors.
Referring to the dispensing unit shown in Figs. 10 and 11, each accessory
dispensing unit is comprised of a plurality of accessory storage columns 180 positioned
adjacent to one another. The accessories are held in small packages, preferably
rectangular boxes (not shown), and are stacked vertically within the storage columns
180. The preferred unit holds approximately 100 units per column, for a total per
column weight of approximately 5 pounds.
The unit is designed such that each column can hold a different accessory
type. During use, the controller instructs the dispensing unit to dispense whichever
of the various accessory types corresponds to the workpiece type selected by the
The dispensing unit 18 has a front side designated 182 in Fig. 10,
and a back side designated 184 in Fig. 11. A plurality of dividing walls 186 separate
the storage columns 180. A front wall 188 covers the front side 182 of the dispensing
unit, although the dividing walls 186 extend below the lower edge of the front
A windowed plate 190 extends across the back side 184 of the dispensing
unit, near the bottom. Extending from the windowed plate 190 towards the front
side 182 of the dispensing unit is a bottom plate 192 (Fig. 12). The bottom plate
192 has a slight downward angle (preferably approximately 5°), and preferably has
a smooth, low friction surface to facilitate the dispensing of accessory packages.
An angular picking window 194 is formed in the windowed plate 190 and the bottom
plate 192. The width of the picking window 194 is smaller than the width of the
accessory boxes (not shown) which are placed in the storage columns 180. Thus,
accessory boxes in the columns 180 are supported by base plate 192 but they are
partially exposed by window 194. A viewing window 195 is also formed in plate 190
to allow the number of accessory boxes in each column to be monitored.
A mounting plate 196 extends laterally from the back side 184 of the
dispensing unit. Secured to the mounting plate 196 is a block 198 which supports
a rail 200. The rail extends behind the dispensing unit as shown in Figs. 11 and
14 and is secured to wall 202 by block 204.
Extending normally of mounting plate 196 is plate 206. Plate 206
supports pulley 208 and place motor 212 (preferably a 3.8 amp, 1.3 V DC stepper
motor) which, when activated, causes rotation of the pulley 208. A second pulley
214 is mounted to an L-shaped plate 216 that is attached to windowed plate 190.
Belt 210 forms a loop which revolves around the pulleys 208, 214. Movement of the
belt 210 around the pulleys 208, 214 is propelled by rotation of pulley 208 by
stepper motor 212.
The picker mechanism, designated generally as 218, is movable between
the columns 180 so that it can eject accessory packages from any column 180. The
picker mechanism 218 is comprised of a carriage 220 slidably mounted on the rail
200 and secured to belt 210 at member 222. A bearing 221 provides a smooth surface
between the carriage 220 and the rail 200 to facilitate sliding. A limit switch
(not shown) is mounted to the dispensing unit at one end of the carriage travel,
and a corresponding triggering device (not shown) is mounted to the carriage 220.
The carriage 220 carries a picker motor 224, which is preferably a
2.9 amp, 3.4 V DC triple stack stepper motor, that rotates a picker arm 226 when
activated. The picker arm is proportioned to rotate through one of the picking
windows 194, thereby pushing an accessory package out the front side 182 of the
accessory dispenser. A chute 228 (Fig. 1) is formed in the engraving booth which
allows the accessory package to slide to a dispensing location 230 once it has
been picked by the picker arm 226 from the storage column 180.
The picker motor 224 can be software driven to affect a motion profile.
This allows a wide range of accessory mass to be accommodated as well as speed
of picking. In order to insure no cumulative speed loss occurs, a detente 232 is
provided in the stepper motor 224 is positioned at zero degrees with enough tolerance
to force or hold the unpowered picker arm 226 into a true zero position. A photoelectric
limit switch may be used in place of the detente 232. This may be preferable in
order to compensate for variations in stepper motor windings.
The picker arm 226 has a tapered end which helps minimize damage
to the accessory package during the dispensing operation. The length of the picker
arm is chosen to ensure positive dispensing by maximizing contact between the picker
arm and accessory package during picker arm travel. The distance to the package,
the moment arm during picker arm rotation, and the required motor power must be
taken into account when selecting the drive components for the picker arm.
Oftentimes an accessory contained in an accessory package will be
shifted to one side of the package, causing uneven distribution of weight in the
package. When package contents are shifted towards the front side 182 of the dispenser,
multiple packages may accidentally be dispensed from one column during a single
picker arm rotation.
To overcome this problem, a rear weighted block (not shown) may be
placed on top of the stack of accessory packages in each column. The preferred
weight block is 0.23kg (.5 pounds); it is rear weighted to insure that the packages
remain horizontal regardless of the number of packages remaining in the column
or the location of the center of mass of each package. This effectively prevents
multiple packages from being "picked" from a column in weight-forward conditions.
The weight block is designed such that if a transaction is attempted
when only the weight block is left in the column (i.e. because of an inventory
mis-count), the picker arm will neither eject the weight block nor collide with
it. This is accomplished by slotting the rear of the weight block such that the
picker arm misses it entirely and shaping the block such that it cannot inadvertently
pass through the picking window 194 opening on the opposite side of the dispenser
The place motor 212 and the pick motor 224 are operated using half-stepping
drivers. To prevent cumulative step loss error, the step counting sequences are
re-set between dispensing jobs.
User Interface and Control
The method and apparatus of the present invention is directed to the
control of an engraving system, including the selection of the workpiece, positioning
of the workpiece in an engraving location, engraving, and dispensing the workpiece
along with the appropriate accessory for the workpiece type. A simplified schematic
representation of the present system is shown in Fig. 15. A user interface 300,
which is preferably a personal computer ("PC") prompts for and processes data supplied
by a user and passes the processed data to a controller 302. The controller 302
converts the data to drive signals which control operation of the workpiece handling
unit 304, the engraving unit 306, and the accessory dispensing unit 308. When
necessary, the controller also delivers error signals to the user interface which
then result in the termination of a job.
A simplified flow diagram showing the function of the user interface
300 is shown in Fig. 16. First, at step 310, the user is prompted to select a
workpiece type. For example, the user may be prompted to chose between a pet tag,
medical bracelet, luggage tag, etc. In the preferred embodiment, the prompt appears
on a video screen equipped with a video touch screen and prompts the user to touch
the area of the screen designating the chosen workpiece.
After the workpiece type selection is entered, step 312, the user
interface terminal prompts the user to enter the text to be engraved onto the
selected workpiece, step 314. At step 316, the user inputs the text using the touch
screen or other input device.
The user may also be prompted for additional information, such as
font type or payment information (e.g., credit card information). If the system
is equipped to take and process (see payment card slot 23 and receipt printer 21
at Fig. 1) credit or debit card information, the PC also performs credit verification
procedures with the assistance of a modem and communication software.
The preferred embodiment is also equipped to communicate with an
off-site central registry which, using a serial number engraved on the workpiece,
maintains records relevant to the workpiece type. For example, when a pet tag is
purchased, the purchaser is prompted for the name and address of the pet owner.
A serial number is engraved on the tag, and the information about the owner is
stored at the central registry under that serial number. Should the pet become
lost, a finder of the pet will be able to contact the pet owner through the central
registry. The information to be maintained at the central registry is normally
stored temporarily in the PC installed in each engraving unit. A computer at the
central registry periodically polls each engraving unit tied into the registry
network to retrieve information obtained by the individual engraving units during
Once the necessary input has been received from the user, the PC
retrieves from its memory the column location for the accessory which is to be
distributed with the engraved workpiece, and the column location for the selected
workpiece, steps 318 - 319. At step 320, the column locations for the accessory
box and workpiece and also the text to be engraved onto the workpiece are transferred
to the controller in the form of a data string. Job information, specifying the
selected workpiece type, is also passed to the controller at step 320 to allow
the controller to retrieve formatting information from its memory. Control for
the job is passed to the controller at step 322.
The PC, via the video screen, next asks the user whether additional
engraved workpieces are desired, step 324. If additional jobs are requested by
the user, the PC again prompts the user for workpiece type, step 310, etc.
Upon receiving control from the PC, step 322, the controller begins
the workpiece selection step of the process. Referring to Fig. 17, the controller
first extracts the column location for the selected workpiece from the data string
supplied by the PC, step 326. Next, at step 328, the controller activates the X-axis
stepper motor (designated 94 in Fig. 2) such that the carriage 80 travels along
the X-axis until it reaches the designated column location. At this point the workpiece
selector block 72 will be engaged with the receiving component 62 associated with
the column containing the selected workpiece (see Figs. 3A and 4).
At step 330, the selected workpiece is moved into the engraving location.
During this step, the controller instructs workpiece positioning stepper 66 to
move through the appropriate number of steps to move the workpiece already captured
in the clamping plate 46 to the engraving location (i.e. on top of the rollers
56). The engraving operation is next performed, step 332, using X-, Y-, Z-axis
movement of the engraving tool as will be described below.
After engraving is complete but before the workpiece is dispensed
at step 344, the accessory corresponding to the selected workpiece is dispensed,
step 333. Referring to Fig. 18, during the accessory dispensing operation the
controller activates the place motor 212 and causes it to travel until the picker
arm 226 is in alignment with the column location provided to the controller by
the PC. After the place motor 212 is turned off, picker motor 224 is activated
to rotate picker arm 226, causing it to knock an accessory package from the column
Returning to Fig. 17, once the accessory is dispensed, the workpiece
is ejected from the workpiece handling unit 14, step 334. During this step, the
controller activates the workpiece positioning stepper motor 66 to move the clamping
plate 46 into the workpiece dispensing location such that the workpiece falls from
the clamping plate 46 and into a dispensing chute. At this point, Z-axis movement
is also initiated to move the engraving tool to the workpiece dispensing location.
This ensures that the workpiece drops from the clamping plate by pressing the workpiece
out of the clamping plate if it has not already fallen from it. Finally, the workpiece
positioning unit 14 is returned to the workpiece capturing position, step 336.
The engraving operation will next be described with reference to Fig.
19. Using the workpiece type information received from the PC, the controller
next retrieves the layout and font information for that selected workpiece, step
342. In the preferred embodiment, this information is predetermined for each workpiece
type and stored in the controller. A table showing an example of the arrangement
and selection of variables for the controller is shown below:
13.3-17.8N (3-4 lbs)
4 lines, single font
3 lines, single font
4 lines, multiple fonts
However, the font may be chosen by the user and the layout may be
calculated using the number of the letters in the desired text, the size of the
workpiece, the size of the font, and other predetermined values such as the percentage
of white space and the length of each line. An engraving system performing calculations
of this type is described in U.S. Patent No. 4,437,150 to Dahlgren et al.
At step 344, the controller instructs X- and Y-axis movement of the
engraving tool to the position on the selected workpiece where engraving will
begin. At this point in the process, the engraving tool will already be close to
the X-axis position necessary to begin the engraving process. This is because the
carriage 80 which carries both the engraving tool and the workpiece positioning
unit 14 will have already moved into alignment with the column containing the selected
workpiece during the step of delivering the selected workpiece to the engraving
position (Fig. 17, steps 328 and 330). However, the X-axis position of the engraving
tool is fine-tuned in step 344 to position the engraving tool for engraving. Y-axis
movement of the Y-axis carriage 118 is likewise needed during step 344 to place
the engraving tool in the proper starting Position.
At step 346, the Z-axis pressure for the selected workpiece is set
by the controller. The Z-axis pressure is predetermined and stored in the controller,
although it also may be calculated by the PC or controller if font size is to be
calculated by the system rather than predetermined for each workpiece. The Z-axis
pressure is set by activating the Z-axis stepper 164 to lower (if pressure is to
be increased to provide a greater stroke width) or raise (to decrease Z-axis pressure
and stroke width) the engraving tool to the position predetermined for the desired
stroke width. Finally, in step 348, the text is engraved onto the workpiece. Engraving
is carried out by starting and stopping the X-axis, Y-axis, and Z-axis stepper
motors as necessary to move the engraving tool to engrave the letters of the desired
text onto the workpiece. A method of combining X- and Y-axis movement in order
to engrave characters onto a workpiece is described in detail in U.S. Patent No.
If additional jobs have been sent to the controller by the PC, the
controller next begins with workpiece selection, positioning, and dispensing (Fig.
15, step 304 and Fig. 17) of the next selected workpiece.
while one embodiment of the present invention have been described,
many others are possible within the scope of the invention. The scope of the invention
is not intended to be limited to the specific embodiment described above, but is
limited only in terms of the appended claims.