The present invention relates to machines for grinding workpieces,
and more specifically to machines for grinding such workpieces as frames, columns,
The grinding of workpieces of variable height and length such as
frames, columns, tables, etc. requires the use of two different types of wheelheads:
tangential wheelheads and anglemovement wheelheads (so-called universal wheelheads).
The use of conventional single-column flat grinders for grinding
workpieces of this type is already known. For this purpose, besides using the wheel
mounted on this column, another carriage with another wheel is fitted to the side
of the grinding machine column, generally possessing angle movement. The machining
table moves in relation to the column during the grinding process.
The conventional grinding machine has the following disadvantages:
- It cannot work with the two wheels at the same time, as the vertical drive
is common to both wheels.
- It has a single machining table, so it is necessary to install costly palletizing
systems alongside it for change of workpiece. In addition, the machine has to be
shut off while the palletizing system is working, with the consequent increase
in time during the grinding process.
The use of bridge grinders for this purpose is also known. Bridge
grinders are grinding machines with two opposing columns, one on either side of
the machining table, and linked transversely by a cross rail. The cross rail mounts
two wheelheads - one of them generally capable of angle movementeach of them with
its own vertical drives and its own transverse drives (up to a limited travel),
the cross rail that links both columns being fixed or vertically movable. During
the grinding process the machining table moves in respect of the columns and the
bridge. These machines are suitable for grinding workpieces of considerable width
and variable lengths.
The use of a bridge grinding machine has the following disadvantages:
DISCLOSURE OF THE INVENTION
- It cannot work with both wheels at the same time, as, although the grinding
wheels have their own drive carriages, the actual machine frame with the cross
rail prevents the wheels from working at the same time as they would have to cross
over (the transverse movement of both wheelheads is effected on a single support
- It requires costly palletizing systems for changing workpieces or high-priced
dual table systems, with a dual table actuating system or table hitch and release
systems, besides the fact that workpiece change means that it is alternately on
each side of the machine.
- Taking into account the workpiece change system, it occupies a tremendous amount
of shop floor space.
- It has a high cost.
The object of the invention is to provide a grinder with simultaneous
grinding with two different wheels, as is defined in the claims.
The grinding machine that is the object of the invention comprises
at least two aligned columns on one side of the machining table or tables on which
the workpieces to be ground are placed, each of said columns being provided with
a wheelhead with its respective grinding wheel. Each one of said wheelheads has
its own vertical and horizontal drive system, at least one of said wheelheads is
capable of angle movement, and both wheels work simultaneously. It is the columns
that move in relation to the machining table or tables.
The machine of the present invention offers the following advantages:
DESCRIPTION OF THE DRAWINGS
- As the two wheels work simultaneously, output is practically doubled. In fact,
the total grinding time is the grinding time of the wheel which has the longer
process, as the grinding time of the other wheel is comprised in this.
- Since it is the columns that move and the heads have all their movements in
relation to said columns, the grinding machine can grind workpieces placed on different
aligned machining tables consecutively. Thus, the machine can be grinding the
workpiece of one machining table, while the operator handles the workpiece of another
table. In this way, the workpiece change time is nil.
- Taking into account the automatic workpiece change, the space occupied by the
machine is smaller than that of a bridge machine and even less than a conventional
grinding machine, as the latter requires palletizing systems.
- There is a considerable saving in costs especially in relation to the use of
a bridge machine.
FIG. 1 is an elevational view of an embodiment of the machine that
is the object of the invention.
FIG. 2 is a profile view of the machine that is the object of the
invention according to section II-II of FIG. 1.
FIG. 3 is a profile view of the machine that is the object of the
invention according to section III-III of FIG. 1.
DETAILED DISCLOSURE OF THE INVENTION
With reference to FIG. 1, the machine 1 of the invention has two
facing and aligned columns 2 and 3, column 2 being provided with a wheelhead 4
and a grinding wheel 6 and column 3 being provided with a wheelhead 5 and a grinding
wheel 7. Both wheelhead 4 and wheelhead 5 have their own vertical drive system
and their own horizontal drive system and can work simultaneously.
In the embodiment of FIG.1 the wheelhead 5 only has tangential movement,
while the wheelhead 4 is capable of being moved in an angular direction as well.
FIG. 2 shows the column 2 together with the wheelhead 4 with its
respective grinding wheel 6. FIG. 2 shows said head 4 in three different positions.
Wheelhead 4 has a vertical drive according to direction B and a horizontal
drive according to direction C. It may be seen that the possibility of angle
movement possessed by the wheelhead 4 permits the grinding of workpieces of widely
varying shapes, such as workpiece 12 for instance. Column 2 is linked to carriage
8, which slides over base 9.
Wheelhead 4 is a so-called universal wheelhead, as it is used in
other types of machine and has all the movements possessed by wheelheads of this
The workpiece 12 for grinding is placed on a fixed machining table
11 (the machine 1 may have more than one machining table 11). The workpieces 12
to be ground are bulky items of considerable length, not usually more than one
metre wide, such as frames, columns, tables, etc for machine tools.
With reference to FIG.3, the wheelhead 5 of this embodiment grinds
horizontal flat surfaces. FIG. 3 shows said wheelhead 5 in three different positions.
The movements that said wheelhead 5 has in relation to the column 3 are the usual
ones possessed by the wheelheads on flat surface grinding machines. Thus, said
wheelhead 5 has a vertical drive according to direction D and a horizontal
drive according to direction E.
Grinding wheels 4 and 5 are large diameter wheels (up to 600 mm)
and have high-power servomotors. The grinding with both wheels is carried out at
the same time with a single numeric control that works in two channels with specific
Columns 2 and 3 of machine 1 are linked at the bottom to a single
lengthwise carriage 8 which slides longitudinally over base 9 according to direction
A, as shown in FIG. 1. This movement is effected by means of a hydrostatic slideway
so as to be able to reach typical conventional grinding speeds (30 m/min).
The hydrostatic slideway enables considerable accelerations and decelerations
to be achieved and, furthermore, it ensures that the movement of the columns is
uniform, thus preventing the appearance of a buckling effect in said columns. In
the embodiment of FIG. 1 columns 2 and 3 are linked at the top by means of a cross
member 10 to prevent said buckling effect. With the use of a hydrostatic slideway,
said cross member 10 is not necessary.
The longitudinal movement of carriage 8 is governed, for instance,
by a rack and pinion and encoder system.
As the assembly formed by carriage 8, columns 2 and 3 and their respective
wheelheads 4 and 5 move en bloc on base 9, it is possible to install various aligned
machining tables 11, each with its respective workpiece 12, along the whole length
of the base 9 and parallel to said base 9. This means that the machine 1 may be
grinding workpiece 12 of one machining table 11, while the operator is handling
the workpiece 12 of another table 11.