EP0912265A1

EP0912265A1 - Device for adjusting the size of a machine tool blank holder

Info

Publication number: EP0912265A1
Application number: EP97932851A
Authority: EP
Inventors: Jean-Claude Jeandeaud
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-07-05
Filing date: 1997-07-07
Publication date: 1999-05-06
Anticipated expiration: 2017-07-07
Also published as: WO1998001245A1; FR2750626A1; FR2750626B1; ATE198845T1; EP0912265B1; DE69703978T2; US6227028B1; DE69703978D1; ES2155692T3

Abstract

A device that includes a frame equipped with guiding means, blank holder modules to be moved along the guiding means, means for blocking independently each blank holder module in a specific position, a magazine of end modules located near each end of the guiding means and gripping and handling means for grasping an end module to fix the end module to a blank holder module and vice-versa.

Description

DEVICE FOR ADJUSTING THE SIZE OF A BLOCK HOLDER

MACHINE TOOL

The present invention relates to a device for adapting the size of a blank holder. A blank holder is a part of a machine tool intended for the machining of elements in the form of sheets, such as a sheet metal, allowing good retention of the machined sheet. We find a blank holder for example on a bending, stamping or folding machine. The size of the blank holder must be adapted to the size of the sheet to be machined and to the operation performed. In order to be able to machine sheets of different sizes on the same machine tool, it is necessary to be able to change the size of the blank holder. It is known to adapt the entire blank holder, without manual intervention, to the size of the sheet to be machined.

The main drawback of the systems known to date and capable of automatically adapting the size of the blank holder is to perform this operation in a relatively long time, thereby limiting productivity compared to flexibility. The time required to machine the sheet is less than the adaptation time of the blank holder by known systems. Therefore, a user seeks to make several pieces of the same dimension before changing the size of the blank holder.

In addition, for reasons of optimization, the manufacturers recommend carrying out first of all on the machine tool equipped with a modular blank holder the operations requiring a short blank holder, then those requiring a long blank holder. The user is therefore led to have to adapt the order of completion of the machining operations as a function of these constraints.

The object of the invention is therefore to provide a device making it possible to adapt the size of a blank holder making it possible to modify this size very quickly in order to improve the flexibility of a machine tool intended to receive this blank holder and allow the various machining operations to be carried out in any order, without altering the cycle time. To this end, the device it offers includes:

- a frame provided with guide means,

- blank holder modules intended to move along the guide means, - means for independently blocking each blank holder module in a given position,

- a store of end modules placed near each end of the guide means,

- gripping and handling means making it possible to grasp an end module in a store to position it against a blank holder module and to remove an end module positioned against a blank holder module to replace it in a store.

A change of configuration of the blank holder can then be carried out very quickly. It suffices to move the blank holder modules which are unnecessary for carrying out a predefined folding towards the ends of the guide means and to group the blank holder modules necessary for this folding in the center of the guide means and then to bring the using the gripping means, an end module at each end of the group of blank holder modules to form a blank holder of the desired size for folding. All these operations can be carried out quickly, since the blank holding modules can move at the same time as the end modules.

Advantageously, a module, called the central module, is mounted fixed relative to the frame and on each side of the central module are mobile blank holder modules; the hold-down modules located on the same side of the central module are all similar and the hold-down modules located on one side of the central module have a length in the direction of the guide means different from those located on the other side of the central module. The central module then serves as a stop when moving the blank-holding modules. The different length of the hold-down modules on one side and the other of the central module makes it possible to offer a greater variety of different lengths of hold-down. If for example all the hold-down modules and the central module have a length of 100 mm, the assembly formed by the hold-down modules and the central module will always have a length multiple of 100 mm. On the other hand, if the blank holding modules on one side have a length of 100 mm and those on the other side have a length of 50 mm or 150 mm, it will also be possible to have multiple total lengths of 50 mm . Of course other values and other length ratios are possible.

In a preferred embodiment, the guide means consist of at least one rectilinear rail secured to the frame. In this case, advantageously, the blank holder modules are mounted on two parallel rails between which a drive bar is guided, and the blocking means make it possible to make each blank holder module independently of the others be secured to the support bar. drive, either integral with the guide rails. To move blank-holding modules, simply make them integral with the drive bar and move the latter with these modules. The other blank holding modules which should not move remain integral with the frame. To move all the hold-down modules to be moved, it suffices to move the drive bar once in one direction with the modules moving in the same direction, then to move the hold-down modules to be moved in the other direction.

In a preferred embodiment, each blank holder module includes a locking piece that can move perpendicular to the guide rails, having a U-shaped section perpendicular to the guide rails, the end of a branch of the U lying in a longitudinal groove made in a rail, the other end of the branch facing the other rail of guide and the drive bar projecting between these two branches. In addition, a spring preloads the locking piece in one direction, making it integral with the frame or the drive bar, and finally, a jack is provided to act 1 "against the spring in order to make the piece of integral locking of the drive bar or the frame.

To drive the drive bar, it is provided with a rack meshing with a toothed wheel driven by a motor. Other means are of course conceivable: the bar can for example be connected to a jack or else to a linear motor.

In the device according to the invention, the gripping and handling means may consist of a clamp moving longitudinally on the frame. We can also consider other solutions, such as a manipulator robot.

The invention also proposes to use a device as described above on a machine intended to produce folds on a sheet, comprising two blank clamps and a folding tool. In such a machine, it is not useful to have two modular hold-downs, only one is generally sufficient.

Such a machine, or folding machine, can adapt the size of its blank holder for the time necessary for the folded sheet to leave and for a sheet to be folded to take place. For sheets to be folded on two opposite sides, the invention then proposes a machining center, characterized in that it comprises two folding machines according to the invention, the two machines facing each other, being able to approach or move away from each other, and that a conveyor intended to convey sheets is placed between the two machines. The conveyor can also be provided with a central rotator, which takes place between the two folding machines, and makes it possible to rotate sheets to be folded on four sides - or more -.

In any case, the invention will be clearly understood with the aid of the description which follows, with reference to the appended schematic drawing representing, by way of nonlimiting example, a device according to the invention. FIG. 1 represents a machine intended for bending sheets, provided with a device according to the invention,

Figures 2 and 3 are schematic front views showing the device in two different positions,

Figure 4 shows a drive mechanism for blank holder modules,

FIG. 5 is a sectional view on an enlarged scale along the line V-V of FIG. 4,

FIG. 6 is a sectional view on an enlarged scale along the line VI-VI of FIG. 4, FIGS. 7 to 10 represent several possible configurations of a device according to the invention,

FIG. 11 shows in side view two folding machines facing each other, each of these being provided with a device according to the invention, and

Figure 12 is a perspective view of an end module.

By way of example of application of a device making it possible to adapt the size of a blank holder, FIG. 1 represents a machine intended for bending sheets provided with such a device.

This machine, or folding machine, comprises a bench 2, a brush table 4 intended to receive a sheet (not shown in this figure) to fold, a folding tool 6, a fixed lower blank holder 8, an upper blank holder 10 mounted on an arm 12 pivoting around a axis 14, as well as a manipulator robot 16 intended to move the sheets to be folded.

The width of the upper blank holder 10 is modular. Thus, the folder can adapt to a large number of sheet sizes and to several types of folding. The means for modifying the size of the blank holder 10 are described below.

Figures 2 and 3 schematically show the upper blank holder 10 of the folder of Figure 1 and the device for varying the width thereof.

The blank holder 10 comprises several blank holder modules 18, 19, all of generally similar shape. When all the hold-down modules 18,19 are one against the other, they form a hold-down resembling known hold-downs.

Figures 2 and 3 show a frame 20 carrying two parallel straight rails 22 on which are guided the blank holder modules 18, two magazines 24,25, each magazine being placed at one end of the frame 20, as well as two guided pieces 26 in translation on the frame 20, parallel to the rails 22.

The hold-down modules 18,19 are of two different widths. In the drawing, the narrower modules 18 are mounted on the side of the left end of the rails 22, while the wider modules 19 are mounted on the right. There are therefore two sets of hold-down modules. These two assemblies are separated by a fixed central module 28, serving as a stop for the mobile hold-down modules 18, 19. The general shape of this central module 28 is similar to that of the mobile hold-down modules 18, 19.

On the frame 20 are arranged two mechanisms for the translation drive of the clamps 26. Each mechanism comprises two pulleys 30, the axes of which are perpendicular to the rails 22. A belt 32 connects these two pulleys 30. A clamp 26 is fixed on the strand upper of the belt 32 and is guided on the lower strand. An electric motor 34 drives a rotating pulley. The latter is at the end of the frame 20. The other pulley 30 is located substantially at the level of the central module 28.

Each magazine 24.25 is intended for the storage of end modules 36.37. Figure 12 shows one of these end modules. By complementarity of form, each end module can be placed on a corresponding blank holder module. The clamps 26 are intended to grip an end module 36,37 stored in its magazine 24,25 to place it on a hold-down module 18,19, or vice versa, as well as to hold the end module 36 , 37 entered in position on the blank holder module 18,19. Each clamp 26 can only serve the hold-down modules 18, 19 located on the same side of the central module 28. Thus, the end modules 36 stored in the magazine 24 located on the left in the figures are intended to take place on a blank holder module 18, while the end modules 37 stored in the magazine 25 located on the right in the figures are intended to take place on a blank holder module 19.

Each clamp 26 comprises a jack 38. Thus, the end of the latter, as well as the gripped end module, have two degrees of freedom. A first degree of freedom (belt) allows the end module to be moved to the corresponding blank holder module and the second degree of freedom (jack) allows the end module to be fitted onto the blank holder module. Figures 4 to 6 illustrate the way in which the holding-down modules 18,19 can move.

These modules are guided on the two parallel rails 22. Between these two rails 22 is a space forming a groove, in which a drive bar 40 is guided. This drive bar 40 is provided with a rack 42 at the 'one of its ends, on which meshes with a toothed wheel 44 driven in rotation by a motor (not shown).

Each blank holder module 18,19 is provided with a device allowing it either to be secured to the rails 22, or to be secured to the drive bar 40. When the drive bar 40 moves, it drives with it the hold-down modules 18,19 which are fixed on it, the others remaining stationary. It is thus possible to individually move each blank holder module, or a group of blank holder modules, or any other possible combination.

Figures 5 and 6 show in section a blank holder module 18 and its associated locking device. The latter notably comprises a locking piece 46, a spring 48 and a pneumatic cylinder 50.

The locking piece 46 is placed in a housing formed in the face of the blank holder module facing the rails 22. This housing is such that the locking piece can move perpendicular to the rails 22. In a cutting plane perpendicular to the rails 22 (Figures 5 and 6), the locking piece 46 has a generally U-shaped section. The branches of the U are oriented towards the rails 22. The end of a first branch is housed in a groove 52 formed longitudinally in a rail 22. The second branch faces the other guide rail 22. The drive bar 40 projects from the two rails 22 and is located between the two branches of the locking piece 46. The second branch of this piece 46 faces the drive bar 40.

On the side of its first branch, the locking piece is subjected to the action of spring 48, which acts in the direction of pushing the first branch of the locking piece towards the drive bar 40. On the side of the second branch is the pneumatic cylinder 50. The latter can act on the workpiece locking 46 against the spring 48 and therefore pushing the second branch in the direction of the drive bar 40.

FIG. 5 shows the position of the blank holder module 18 when the jack 50 does not act. The spring 48 then pushes the locking piece 46 towards the drive bar 40. The first branch of this locking piece 46 then comes to bear against the wall of the groove 52 formed in a rail 22. Against reaction, the module blank holder 18 moves in the opposite direction, that is to say to the left in FIG. 5. The module 18 then comes to bear on the external face of the rail 22 opposite to the spring 48. Thus, the clamp module -flan is blocked on the two rails 22 and is therefore secured to the frame 20.

FIG. 6 shows the position of the blank holder module 18 when the jack 50 acts. The jack 50 then pushes the locking piece 46 so that its second branch comes to bear against the drive bar 40. Against reaction, the blank holder module 18 moves in the opposite direction of movement of the piece of locking 46, that is to say to the right in FIG. 6. The dimensions of the various guide grooves allowing the guide of the blank holder module 18 on the rails 22 are such that the blank holder module 18 then comes in support on the drive bar 40, and not on the rail 22 opposite the pneumatic cylinder 50. In this way, the blank holder module 18 is integral with the drive bar 40. Figures 7 to 10 show several possible configurations blank holder, among many others, obtained by combining blank holder modules 18,19 and end modules 36,37. Figure 7 shows a configuration where all the blank holding modules 18,19 are grouped around the module central 28 and at each end there is an end module 36,37.

Figure 8 shows another configuration. To go from the configuration of FIG. 7 to that of FIG. 8, several steps are necessary but they can be carried out very quickly. The end modules 36, 37 are first replaced in their respective stores. The three left-most blanking modules 18 in FIGS. 7 and 8 are made integral with the drive bar 40. The latter is moved to the left. The pressure in the jacks 50 corresponding to these three blank holder modules 18 is released. These modules therefore become integral with the rails 22 and are fixed relative to the frame 20. The three blank-holding modules 19 furthest to the right in FIG. 7 are then made integral with the drive bar 40 by placing the corresponding jacks 50 under pressure. All the other hold-down modules 18, 19 remain integral with the rails 22 and are fixed relative to the frame 20. The drive bar 40 moves to the right, carrying with it the three hold-down modules 19.

While these movements of the holding-down modules 18,19 are taking place, the clamps 26 each grip an end module 36,37 in a corresponding magazine 24,25 and position it on the module 18,19 forming the end of the hold-down.

If in a folding carried out subsequently by the folder, it is not necessary to have an end module at the end of the blank holder, the end modules 36, 37 can remain in place and be found between two blank holding modules 18,19, as shown in FIG. 9. The time required to change the configuration can then be slightly reduced. Figure 10 shows a configuration where an end module 37 is placed directly on the central module 28. It is thus possible to have a blank holder of small width.

By judiciously choosing the widths of the blank holder modules 18,19 and the end modules 36,37, it is possible to cover a whole range of widths for the blank holder obtained with a predetermined increment. The example of dimensions indicated below makes it possible to obtain all the widths multiple of 5 mm starting from the width of 310 mm. It is thus possible, for example, to choose blank holder modules 18 with a width of 100 mm, which will be found in the example shown in the drawing to the left of the central module 28, blank holder modules 19 with a width of 150 mm. , which will be to the right of the central module 28, four end modules 36 associated with the magazine 24 and therefore intended to be mounted on hold-down modules 18 of 80 mm, 90 mm, 100 mm and 105 mm, and four modules d end 37 associated with magazine 25 and therefore intended to be mounted on blank holder modules 19 of 80 mm, 85 mm, 95 mm and 105 mm. If, as shown in FIGS. 7 to 10, the blank holder comprises five blank holder modules 18 of 100 mm and four blank holder modules 19 of 150 mm, it is possible to assemble the various modules 28, 18, 19, 36, 37 to obtain any width of blank holder multiple of 5 mm and between 310 mm and 1310 mm.

Of course, the movement of the clamps 26 and the drive bar 40 can be managed with the help of a computer (not shown), which, depending on the width of the blank holder required and the type of fold to carry out, calculate the configuration to be adopted and the routes of the various organs then supply this information to a central control system which manages the movement of these organs.

The design of the modular blank holder as described above makes it possible to switch from one configuration to another in a very short time, from the order of ten seconds. It thus becomes possible to change the configuration at the same time as the sheet or the position of this sheet is changed. Unlike the machines known so far, which require a time approximately ten times greater, it is possible to change the configuration of the blank holder in masked time.

It then becomes conceivable to place two folding machines facing one another, as shown in FIG. 11. A conveyor, not shown, provides a sheet 54 between the two folding machines. A central rotator 56 is located between the two bending machines to turn a sheet which could possibly be folded on four sides - or more -. Of course, to adapt to the different dimensions of the sheet and to the type of fold to be produced, the two folding machines must be able to move apart and get closer to each other. For this purpose, they are both mounted on a common bench 58. A computer and a central control system can be provided to calculate and manage the movements of the two folders on the common bench 58, but they can also manage the modular hold-downs of the two folders.

It goes without saying that the invention is not limited to the embodiment described above by way of non-limiting example; on the contrary, it embraces all its variants.

Thus, for example, each blank holder module could be equipped with motor means allowing it to move by itself on guide means. The drive bar would be replaced by a fixed rack extending over the entire length of the frame and each blank holder module would be equipped with a motor at the end of the shaft from which would be mounted a toothed wheel. A motor brake would prevent the toothed wheel from turning, thus ensuring the blocking of the module relative to the frame. The modules could be guided on guide columns. The device for adapting the size of a blank holder is not necessarily suitable for a folder. It can very well be mounted on any machine comprising a blank holder, such as a bending or stamping machine.

The size, shape and number of modules are given only as examples to illustrate the invention. It is of course possible to multiply the number of modules to increase the number of possible configurations.

Claims

1 - Device for adapting the size of a blank holder (10), characterized in that it comprises:

- a frame (20) provided with guide means (22), - blank holder modules (18,19) intended to move along the guide means,

- means (46,48,50) for independently blocking each blank holder module (18,19) in a given position, - a magazine (24,25) for end modules

(36,37) placed near each end of the guide means,

- gripping and handling means (26) for gripping an end module (36,37) in a magazine (24,25) to position it against a blank holder module (18,19) and removing a end module (36,37) positioned against a blank holder module (18,19) to replace it in a magazine (24,25).

2 - Device according to claim 1, characterized in that a module, called central module

(28), is mounted fixed with respect to the frame (20) and in that on each side of the central module (28) are mobile hold-down modules (18,19), the hold-down modules being located the same side of the central module being all similar and the blank holding modules located on one side of the central module having a length in the direction of the guide means different from those located on the other side of the central module.

3 - Device according to claim 1 or 2, characterized in that the guide means consist of at least one rail (22) rectilinear integral with the frame (20).

4 - Device according to claim 3, characterized in that the blank holder modules (18,19) are mounted on two parallel rails (22) between which is guided a drive bar (40), and in that the blocking means (46,48,50) make it possible to make each blank holder module (18,19) independently of the others either secured to the drive bar (40) or secured to the guide rails (22). 5 - Device according to claim 4, characterized in that each blank holder module (18,19) comprises a locking piece (46) which can move perpendicular to the guide rails (22), having a cross section perpendicular to the guide rails in a U, the end of a branch of the U being in a longitudinal groove (52) produced in a rail (22), the other end of the branch being in front of the other guide rail (22) and the drive bar (40) protruding between these two branches, in that a spring (48) prestresses the locking piece (46) in one direction, making it integral with the frame (20) or the bar drive (40), and in that a jack (50) is provided to act against the spring (48) in order to make the locking piece (46) integral with the drive bar (40) or of the frame (20). 6 - Device according to claim 4 or 5, characterized in that the drive bar (40) is provided with a rack (42) meshing with a toothed wheel (44) driven by a motor. 7 - Device according to one of claims 1 to

6, characterized in that the gripping and handling means consist of a clamp (26) moving longitudinally on the frame (20).

8 - Machine intended to produce folds on a sheet, comprising two blank clamps (8,10) and a folding tool (6), characterized in that it comprises a device making it possible to adapt the size of a greenhouse blank (10) according to one of claims 1 to 7.

9 - Machining center, characterized in that it comprises two machines according to claim 8, the two machines facing each other, being able to approach or move away from each other, and in that a conveyor intended to convey sheets is placed between the two machines.

10 - Machining center according to claim 9, characterized in that it further comprises a central rotator (56) placed between the two machines intended to produce folds on a sheet.