GB2156258A - Device for positioning a workpiece - Google Patents

Abstract

A workpiece positioning device viz a back gauge 13 comprises two independently movable support members 17L 17R and a beam member 19 which is supported by the support members and is horizontally pivotally movable with respect to each support member, vertically pivotally movable with respect to one of the support members 17L and longitudinally slidable with respect to the other support member 17R. Stops 21L, 21R on the beam have work-abutting members 23L, 23R mounted on them for pivoting movement about hinges 27L, 27R. <IMAGE>

Description

SPECIFICATION Device for Positioning a Workpiece This invention relates to a device, such as a backgauge device, for positioning a workpiece and, in particular, to a device for positioning a sheet metal workpiece in a machine tool such as a shearing machine or a press brake.

In shearing machines, press brakes and the like, in order accurately to carry out the positioning of a sheet metal workpiece relative to the position at which the workpiece is to be processed by means of upper and lower processing tools, a backgauge device is usually provided which is freely movable forwards and backwards with respect to the working position. The backgauge device comprises abutment means against which the workpiece can be positioned. In a previously proposed backgauge device a pair of guide members are spaced apart from each other to the left and to the right and extend forwards and backwards. On each guide member is supported a respective movable member which is freely movable forwards and backwards.A beam member, which supports a plurality of abutment means or stops extending to the left and to the right to enable controlled positioning of the workpiece to be carried out, is fixed adjacent opposite ends thereof to the movable members. In order to move each movable member forwards and backwards along the respective guide member, right and left ball screws are provided close to and parallel to the right and left guide members, respectively, and a ball nut which is threaded onto each ball screw is integrally connected to the respective movable member. In order to drive the ball screws in rotation, a servomotor is connected to one ball screw and the left and right ball screws are operatively linked through a gear mechanism or chain mechanism, so that they rotate synchronously.

Because more than one ball screw is rotated by means of a single servomotor, a comparatively large servo-motor is required and the overall construction must thus be robust and complex in construction. Also, the left and right movable members must be moved uniformly and accurately so as not to bend or otherwise distort the beam.

Thus, the portion of each guide member which guides and supports the respective movable member must be accurately and precisely mounted.

It is an object of the present invention to enable the provision of a device for positioning a workpiece whereby the above disadvantages may be overcome or at least mitigated.

Accordingly, the present invention provides a device for positioning a workpiece, which device comprises first and second movable support members and a beam member which is supported by the support members, the beam member being movably mounted with respect to one or each of the support members.

Thus, even if the first and second support members are not perfectly synchronized, distortion of the beam is reduced because it can move relative to one or both support members. Thus, it is unnecessary to synchronize and control the movement of the support members as precisely as in the device discussed above. Also it is unnecessary to provide highly precise guide means, so that guide means can be installed more easily.

The present invention enables the provision of a backgauge device in which the beam member can be pivoted in a horizontal plane as required.

In a preferred aspect of the present invention, one end of the beam member is supported in a horizontally rotatable manner by one movable support member, while the other end of the beam member is supported in a longitudinally slidable manner by the other movable support member.

In a further preferred aspect, the present invention provides a backgauge device having separate drive means for left and right support members.

For a better understanding of the present invention, and to show how the same may be put into effect, reference will now be made, by way of example to the accompanying drawings, in which: Figure 1 is a perspective view of a press brake incorporating a device in accordance with the invention, Figure 2 is an enlarged sectional view taken along the line Il-Il of Figure 1, Figure 3 is a sectional view taken along the line Ill-Ill of Figure 2, Figure 4 is an enlarged sectional view taken along the line lV-lV of Figure 1, Figure 5 is a sectional view taken along the line V-V of Figure 4, and Fig. 6 is a sectional view taken along the line VI-VI of Fig. 4.

With reference to Fig. 1, a press brake 1 is illustrated in the form of a metal plate working device in which a workpiece W of metal plate processed. The press brake 1 is comprised of two C-type left and right side frames 3L and 3R, which are separated and installed on the left and the right, along with an upper frame 5 which is supported at the upper portion of the side frames 3L and 3R, and a lower frame 7 which is supported at the lower portion of the side frames 3L and 3R. Mounted on the lower portion of the upper frame 5 is an upper tool 9 such as, for example, a punch positioned in the left to right direction, and mounted on the upper section of said lower frame 7 is a lower tool 11 such as a die which processes the workpiece W in cooperation with the upper tool 9.As is commonly understood, on the press brake 1, the upper frame 5 or the lower frame 7, whichever is appropriate, is raised and lowered, so that the folding of the workpiece W is carried out by means of the engagement between the upper tool 9 and the lower tool 11, and in the rear direction of the work position formed by the upper tool 9 and the lower tool 11, a backgauge device 13, which carries out the predetermined positioning of the workpiece W, is installed.

As has already been made clear, an example of the backgauge device 13 of the press brake 1 is given for this embodiment of the present invention, however, it should be understood that the backgauge device 13 is'not limited to the press brake 1, but is also capable of being applied to other plate metal working devices such as shearing machines.

As has already been made clear in Fig. 1, the backgauge device 13 is constructed so that it is capable of carrying out the positioning of the workpiece Win the forward and backward direction.

That is to say, two left and right guide devices 15L and 15R, constructed so that they are aligned in the forward and backward direction on the back surface of the lower frame 7, are installed such that they are separated horizontally left and right, and on the side devices 15L and 15R, movable bodies 17L and 17R are respectively guided and supported such that they are freely movable in the forward and backward direction. The movable bodies 17L and 17R support a beam member 19 near the opposite ends thereof, which beam member is extended in the left and right directions, and on the beam member 19 a plurality of work stopper devices 21 L and 21 R are installed such that they are freely adjustable, with regard to position, in the left and right directions.Furthermore, when the beam member 19 is long, the movable members 17L and 17R support the beam member 19 notnearthe opposite ends thereof, but at portions remote from the opposite ends so as to prevent the beam member 19 from bending as a result of its dead load. By means of the above configuration, the left and right movable bodies 17L and 17R, by suitably moving in the forward and backward direction, can movably position the beam member 19 in the forward and backward direction.Accordingly, after the positioning of the beam member 19 in the forward and backward direction has been carried out, it becomes possible to carry out the positioning of the workpiece Win the forward and backward direction by means of contact between the rear end of the workpiece W and butting members 23L and 23R which are provided on the work stopper devices 21 and 21 R which are supported on the beam member 19.

A detailed illustration has been omitted, however, the butting members 23L and 23R provided on the work stopper devices 21 and 21 R, are rotatably supported in a vertical direction through the medium of hinge pins 27L and 27R by elevating bodies 25L and 25R which are installed so that they vertically movable and vertically adjustable on the work stopper devices 21 and 21 R. The rotatable motion of the butting devices 23L and 23R in the upward direction, can be carried out automatically, for example, by means of a configuration in which a suitable plunger pushes down the butting devices 23L and 23R at the base side edge thereof, or by means of a suitable mechanism in which the rotation of the hinge pins 27L and 27R is carried out by means of a rack and pinion mechanism.In addition, the vertical movement of the elevating bodies 25L and 25R can be carried out automatically by means of a multi-cylinder comprising a plurality of air cylinders or hydraulic cylinders arranged in series or by means of thread mechanisms.

Accordingly, on the work stopper devices 21 and 21 R, it is cpable of aligning the height of the butting members 23L and 23R at the height of the rear end of the workpiece W by means of vertically moving the elevating bodies 25L and 25R, even, for example, in the case where the rear end of the workpiece W is formed in an almost Z-shaped stepped-form.

In addition, at the time, for example, of the folding of the workpiece W, any worries that the rear end of the workpiece W will interfere with the butting members 23L and 23R, or similar worries, can be alleviated by causing the butting members 23L and 23R to rotate in the upward direction.

With reference to Fig. 1 to Fig. 4, one of the guide devices, 1 SL, is constructed such that one of the movable members, which suitably supports one edge of the beam member 19 is automatically moved and positioned in the forward and backward direction. That is to say, the front edge of a base member 29L, which extends in the forward and backward direction and has its cross-section formed as a channel, is mounted on the back face of the bottom frame 7 by means of a bracket 31 L. A guide member 33L, which extends in the forward and backward direction, is mounted on this base member 29L and at the same time a threaded rod 35L extending parallel to the guide member 33L is supported in a freely rotatable manner by means of bearings.The previously mentioned movable body 17L is supported in a freely movable manner on the above-mentioned guide member 33L, and a nut member 37L, which is integrally connected with the movable body 17L, is threaded onto the threaded rod 35L.

Accordingly, by suitably rotating the threaded rod 35L, the movable body 17L is moved in the forward and backward direction parallel to the guide member 33L, by means of the nut member 37L. As a result, the beam member 19 which is suitably supported by the movable body 17L, is made to move in the forward and backward direction, and the movement and positioning of the work stopper mechanisms 21 and 21 R in the forward and backward direction becomes possible.

In order to carry out the movement and positioning of the movable body 17L automatically in the forward and backward direction, a rotational drive device 39L, such as a pulse motor or servomotor, for example, is operatively connected to the previously mentioned threaded rod 35L. That is to say, in this embodiment of the present invention, the rotational drive device 39L is mounted on the back end of the base member 29L, and an output shaft 41 L of this rotational drive device 39L is operatively connected to the threaded rod 35L. Accordingly, the movable body 17L is automatically moved in the forward and backward direction by the suitable rotation of the rotational drive device 39L. When the movable body 17L is moved in the forward and backward direction, it is possible to use a suitable position-detecting mechanism, with a configuration by which, for example, the threaded rod 35L or the rotational drive device 39L, is operatively connected to a pulse encoder or the like, and, for example, a suitable linear scale, such as a magnetic scale, can be provided parallel to the guide member 33L, as a mechanism to detect the moving position in the forward and backward direction of the movable body 17L. That is to say, by using a position detecting mechanism, and carrying out feed back control or the like, it is possible to precisely carry out the movement and positioning of the movable member 17L.

In order to regulate the forward and backward limits of the movable member 17L, two sensors 43A 43B, for example, limit switches or the like, are installed near the front edge and back edge of the base member 29L respectively, and a dog 45L is mounted on the movable body 17loo activate the sensors 43A and 43B. When the sensors 43A and 43B are activated by the dog 45L, the movable body 17L detects that the movable limit in the forward or backward direction has been reached, and acts to halt the rotation of the previously mentioned rotational drive device 39L.

Accordingly, any over-run by the movable body 17L in the forward or backward direction can be prevented by the action of the sensors 43A and 43B.

However, in order to even more precisely impede the movement of the movable body 17L beyond the limits in the forward and backward direction, a bracket 49L which supports an elastic member 47L, formed from, for example, rubber or the like, is mounted near the back edge of the base member 29L, and an elastic member 51 L is mounted near the front edge. The elastic members 47L and 51 L freely contact the nut member 37L integral with the movable body 17, whereby, when the nut member 37L is contacted, the shock is absorbed, and the movement of the nut member 37L is impeded.

Accordingly, even in the case where the sensors 43A and 43B make inadequate contact when the movable body 17L and the like move in the forward and backward direction, it is capable of preventing any adverse consequences resulting from movement in the forward and backward direction exceeding the limit of movement.

The configuration of the guide device 15R is almost identical to that of the previously discussed guide device 15L, so that a structural member fulfilling an identical function is indicated by appending an R to the identical reference number, and a detailed explanation is omitted.

As has already been understood, the left and right movable bodies 17L and 17R will move in the forward and backward direction on the left and right devices 1 SL and 1 SR, as the result of a rotational motion instruction to both of the rotational drive devices 39L and 39R. Accordingly, it is possible to movably position the work stopper devices 21 and 21 R in the left and right direction, for example, by supporting the beam member 19 substantially parallel to the lower tool 11.In addition, as required, by giving movement instructions for a different number of rotations individually to the rotational drive devices 39L and 39R, different positions are obtained in the forward and backward direction for the left and right movable bodies 17L and 17R, and it is possible to obtain a slanted position in the forward and backward direction for the beam member 19.

That is to say, the beam member 19 is supported by the forward and backward movable bodies 17L and 17R in a way that makes it possible to position the beam member 19 at an angle in the left and right direction. To explain in more detail, as illustrated in Fig. 3 to Fig.5, screw posts 53L and 53R are upright installed on the upper section of the left and right movable bodies 17L and 17R, and on each of the screw posts 53L and 53R, tubular bodies 57L and 57R are rotatably supported through a plurality of bearings 55. The positions of the tubular bodies 57L and 57R in the vertical direction are regulated by means of upper and lower nut members 59L and 59R which are threaded onto each of the screw posts 53L and 53R.Accordingly, each of the nut members 59L and 59R are made to rotate and move in the vertical direction to adjust the tubular bodies 57L and 57R to a suitable height.

As illustrated in detail in Fig. 3 and Fig. 4, brackets 61 and 61 R are aligned respectively in the left and right direction and mounted integrally to each of the above-mentioned tubular bodies 57L and 57R, and a horizontal shaft 63 is suitably mounted on one of the brackets, 61 L. One end of the beam member 19 is supported vertically rotatably on the shaft 63. In addition, a sliding guide 65 is aligned horizontally in the left and right direction and mounted integrally to the other bracket 61 R, and the other end of the beam member 19 is slidably supported on the slide guide 65.That is to say, the beam member 19 is vertically adjustably and horizontally and vertically rotatably supported in relation to the one screw post 53L and vertically adjustably, horizontally rotatably and longitudinally slidably in relation to the other screw post 53L As can be understood by means of the configuration outlined above, the beam member 19 is freely adjustable with respect to position in the vertical direction, and it is capable of accommodating both the slant in the vertical direction of the beam member 19 when the adjustment of the position of the beam member 19 is being carried out by vertical movement, and the winding action of the guide members 33L and 33R (the fluctuation of the screw posts 53L and 53R in the left and right direction) as a result of the winding of the lower surface of the base members 29L and 29R, by means of the rotational action in the vertical direction around the shaft 63, and by means of the sliding action in the longitudinal direction in relation to the slide guide 65. Accordingly, even when, for example, the accuracy of the installation of the guide members 33L and 33R is so poor in relation to the base members 29L and 29R that the screw posts 53L and 53R are slightly slanted at the time of the movement of the movable members 17L and 17R which are supported and guided by the guide members 33L and 33R, the slant of the screw posts 53L and 53R can be absorbed. Accordingly, it is possible to cope with positioning problems even in the case where the accuracy of the installation of the left and right guide members 33L and 33R is more or less poor.In addition, for the base members 29L and 29R, it is not essential that the mounting surface of the guide members 33L and 33R be accurately processed, but a simple non-bending construction is sufficient. In other words, in comparison with conventional units, the mounting of the guide members 33L and 33R to the base members 29L and 29R becomes very simple, and it is not necessary that the base members 29L and 29R be strongly constructed for working, and consequently they can be of an exceedingly light-weight construction.

In addition, as a result of the fact that the tubular bodies 57L and 57R which support the beam member 19 are freely rotatable in relation to the left and right screw posts 53L and 53R and as a result of the fact that it is possible for the beam member 19 to slide in the longitudinal direction in relation to the slide guide 65, the beam member 19 is capable of slanting in the forward and backward direction.

Accordingly, it is obvious that it is possible to cause the beam member 19 to slant intentionally in the forward and backward direction, and, for example, when an instruction is given simultaneously to the left and right movable members 17L and 17R to rotate for movement in the forward and backward direction, even if one of the movable members 17L and 17R is slightly delayed, the desired results can be achieved. That is to say, even if there is a delay in the synchronism of the movable bodies 17L and 17R at the time of movement, it is possible to obtain accurate positioning of the beam member 19 when finally both of the movable bodies 17L and 17R become accurately positioned.

In addition, because the left and right movable bodies 17L and 17R are made to move by means of the separate rotational drive devices 39L and 39R, it is possible to fabricate each of the rotational drive devices 39L and 39R in a comparatively small size, and together with providing a light, compact supporting construction, the movement of the movable bodies 17L and 17R can be speeded up because of their low inertia.In addition, in this embodiment of the present invention, the beam member 19 is constructed so that in relation to the one screw post 53L it is freely adjustable with regard to vertical position and supported in a freely rotatable manner in both the horizontal and vertical directions, while in relation to the other screw post 53R it is freely adjustable with regard to vertical position, horizontally rotatable, and supported in the longitudinal direction in a freely slidable manner. However, it would be further desirable if the beam member 19 were constructed so that, in relation to the other screw post 53R, it were freely adjustable with regard to vertical position, and freely rotatable horizontally, and also freely rotatable in the vertical direction, as well as being supported so that it were freely slidable in the longitudinal direction.

With reference to Fig. 4 and Fig. 6, a bracket 69 provided with a cam 67 which is slanted in the forward and backward direction is integrally mounted on the previously discussed bracket 61 R, and a scale 71 provided for the beam member 19 and a corresponding pointer 73 are mounted on the bracket 69.

In addition, a detection device 75, such as a limit switch activated by the cam 67, is mounted on the previously discussed beam member 19. When the beam member 19 is parallel to the lower tool 11, the above-mentioned pointer 73 indicates the zero point, and when the beam member 19 slants in the forward and backward direction, the scale position corresponding to the angle of inclination is indicated. Accordingly, by reading the point on the scale indicated by the pointer 73, the angle of inclination of the beam member 19 in the forward and backward direction is known.

In addition, when the beam member 19 is slanted at a large angle in the forward and backward direction, the previously mentioned detection device 75 makes contact with the cam 67 and is engaged with and activated by the cam 67.

Accordingly, by the activation of the detection device 75, the fact that the beam member 19 is inclined at a large angle in the forward and backward direction can be detected, and any inconvenience caused by the beam member inclined unnecessarily largely can be prevented.

As has already been explained, as a result of the present invention, the manufacture of a backgauge has been simplified, and as well as making it possible to form the entire unit in light-weight construction, it also becomes possible to slant the unit in the forward and backward direction if required.

Claims (20)

1. A device for positioning a workpiece, which device comprises first and second movable support members and a beam member which is supported by the support members, the beam member being movably mounted with respect to one or each of the support members.

2. A device according to Claim 1, wherein the beam member is slidably mounted with respect to one or each of the support members.

3. A device according to Claim 2, wherein the beam member is slidably mounted with respect to the first support member and fixed against sliding movement with respect to the second support member, whereby the first support member can slide along the beam member towards and away from the second support member.

4. A device according to Claim 1,2 or 3, wherein the beam member is pivotally mounted with respect to one or each of the support members.

5. A device according to Claim 4, wherein the beam member is mounted for pivotal movement with respect to one or each of the support members in a plane, which plane contains the intended direction of motion of the respective support member and a line joining the support members.

6. A device according to Claim 5, wherein the beam member is mounted for pivoted movement with respect to each of the support members in the said plane.

7. A device according to Claim 5 or 6, wherein the said plane is substantially horizontal in use, the said iine extending transversely of the intended direction of motion of the respective support member.

8. A device according to any one of Claims 4 to 7, wherein the beam member is mounted for pivotal movement with respect to one or each of the support members in a plane which is intersected by the intended direction of motion of the respective support member.

9. A device according to Claim 8, wherein the beam member is mounted for pivotal movement with respect to each of the support members in the said intersected plane.

10. A device according to Claim 8, wherein the beam member is fixed against pivotal movement with respect to the first support member in the said intersected plane and mounted for pivotal movement with respect to the second support member in the said intersected plane.

11. A device according to Claim 8,9 or 10, wherein the said intersected plane is substantially vertical in use and is substantially perpendicular to the intended direction of motion of the respective support member.

12. A device according to any one of the preceding claims, which device further comprises means for detecting movement of the beam member relative to one or each of the support members.

13. A device according to any one of the preceding claims, wherein the first and second support members are independently movable.

14. A device according to any one of the preceding claims, wherein the position of the beam member with respect to one or each of the support members is adjustable.

15. A device according to Claim 14, wherein the position of the beam member with respect to one or each of the support members is adjustable in a direction which is perpendicular to a plane containing the intended direction of motion of the respective support member and a line joining the support members.

16. A workpiece positioning device comprising a plurality of elongate parallel guide members, first and second support members, each of which is supported by a respective guide member and is independently movable along the guide member, and an elongate beam member for supporting abutment means for abutting a workpiece, which beam member extends transversely of the guide members and is supported at or near one end thereof by one of the support members and is longitudinally slidably supported at the other end thereof by the other support member.

17. A backgauge device, substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

18. A machine tool whenever comprising a workpiece positioning device in accordance with any one of the preceding claims.

19. A press brake, substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

20. Any novel feature or combination of features described herein.