ES2832653T3 - Stretch bending machine and procedure for deforming a workpiece - Google Patents

Abstract

Stretch bending machine (1) for deformation of workpieces (2), the stretch bending machine (1) comprising a machine frame (3); a first clamping device (4) with a first clamping head (5) for clamping a first side (8) of the workpiece (2), the first clamping device (4) being arranged on the frame of the machine (3); a second clamping device (6) with a second clamping head (7) for clamping a second side (9) of the workpiece (2), the second clamping device (6) being arranged at a distance (10) of the first clamping device (4) on the machine frame (3) and the two clamping heads (5, 7) being configured to apply a traction force in the tension direction (13) to the workpiece ( 2); a pressure device (14) with a pressure die (15) to deform the workpiece (2), the pressure device (14) being arranged on the machine frame (3) between the first clamping receiver ( 4) and the second clamping receiver (6), the pressure die (15) being configured to apply a compression force in a compression direction (16) transverse to the traction direction (13), the two clamping devices being clamping (4, 6) configured to be flexible with respect to the application of the pulling direction (13), characterized in that the two clamping supports (4, 6) each comprise an electric motor (61, 62), in particular a servomotor, to adjust the clamping head (5, 7) and thus apply a traction force to the workpiece (2).

Description

DESCRIPTION

Stretch bending machine and procedure for deforming a workpiece

The invention relates to a stretch bending machine for deforming workpieces and to a workpiece deformation method using the stretch bending machine.

Several state-of-the-art stretch bending machines are known in the current state of the art, in which the part to be processed is clamped between two hydraulically actuated clamping devices and a traction force is exerted on the part in the direction of the tension by means of a hydraulic cylinder. By means of a pressure die of a pressure device, a pressure force is exerted on the workpiece transversely to the pulling direction, the pressure die being also driven by a hydraulic cylinder.

From EP 2910 318 A1, US 2013/008221 A1 and US 2459 132 A, stretch-bending machines of the generic type are known.

The stretch bending machines known from the state of the art have the disadvantage that the application of the tensile force to the workpiece and also the deformation of the workpiece by these known stretch bending machines have only insufficient precision.

The aim of the present invention was to overcome the disadvantages of the prior art and to provide a stretch bending machine and a process for deforming workpieces by means of which the part can be deformed with high precision.

This objective is achieved with a device and a method according to the claims.

According to the invention, a stretch bending machine is configured for deformation of workpieces. The stretch bending machine comprises:

a frame of the machine;

a first clamping device with a first clamping head for clamping a first side of the workpiece, the first clamping device being arranged on the frame of the machine;

a second clamping device with a second clamping head for clamping a second side of the workpiece, the second clamping device being arranged on the frame of the machine spaced from the first clamping device and wherein the two clamping heads are configured to apply a pulling force to the workpiece in the direction of pulling;

a clamping device with a pressure die for deforming the workpiece, the pressure device being arranged on the machine frame between the first clamping device and the second clamping device, the pressure die configured to apply a compression force in a compression direction transverse to the tension direction.

The two clamping devices are configured to be flexible with respect to applying the direction of pull.

The advantage of the design of the stretch bending machine according to the invention is that the clamping devices can be flexibly adapted to the respective degree of deformation of the part to be deformed.

Furthermore, the two clamping devices each comprise an electric motor, in particular a servo motor, for adjusting the clamping head and are therefore configured to apply a pulling force to the workpiece. Thanks to the electric motor drive of the clamping device, the clamping heads are positioned with a high degree of precision.

In addition, the electromotive drive by means of the clamping heads allows a high tensile force to be applied to the part, so it can be adjusted and dispensed with ease. Furthermore, such a drive can be integrated into the stretch bending machine in a simple, cost-effective and space-saving manner. Furthermore, it is not necessary to provide a hydraulic unit for electromotive drive, which simplifies the operation of the stretch bending machine and can also be done in an environmentally friendly manner. Furthermore, it may be expedient that the electric motor of the clamping device, in particular with the interposition of a reducer, is coupled to an adjusting thread, in particular a ball screw drive, the electric motor being housed in a motor support and the clamping head mounted on the motor mount so as to be adjustable relative to the motor mount by a linear guide, the ball screw drive being configured to introduce a linear adjustment and a clamping force into the clamping head. . An advantage here is that a screw drive, in particular a ball screw drive, is configured to transmit high forces and has the least possible play. The clamping head can be mounted on the motor bracket by means of the linear guide so that it can be moved horizontally.

Furthermore, provision can be made for the pressure die to be arranged in an adjustable manner on the frame of the machine. by means of an electric motor, in particular a servo motor, the electric motor being housed in a motor bracket which is coupled to the frame of the machine and the pressure die mounted to the frame of the machine so as to be adjustable in relation to the motor support by means of a linear guide, an adjustment thread being, in particular a ball screw drive, configured to introduce a linear adjustment and an adjustment force into the pressure die and being coupled to the electric motor of the device printing, in particular with the interposition of a reducer. An advantage here is that a screw drive, in particular a ball screw drive, is designed to transmit high forces and has the lowest possible play.

Furthermore, it may be provided that the clamping device has a base unit that is coupled to the frame of the machine and has a rotary unit that is mounted on the base unit so that it rotates with respect to an axis of rotation, the electric motor being together with the motor support and also the clamping head included in the rotating unit and being able to rotate together relative to the base unit of the clamping device. The advantage here lies in the fact that, by means of such an embodiment, the clamping head can rotate freely together with the workpiece during deformation of the same, and therefore the pulling force on the workpiece can be adapted. flexibly according to the current deformation angle and is constantly applied to clamping the workpiece along a neutral fiber thereof.

Another advantage is a feature according to which it can be provided that the rotating unit of the clamping device is coupled to an actuator, in particular a hydraulic cylinder or a pneumatic cylinder, by means of which the rotating unit can be actively rotated to the base unit. The advantage in this case is that the turning unit can be actively turned by this measure and can thus return to its initial position or to its pick-up position after the bending process has been completed.

According to a further refinement, it is possible that the clamping head is configured for receiving workpieces made as a hollow profile, whereby an internal clamping unit is configured which serves for frictional clamping of an inner side of the workpieces and whereby an external clamping unit is configured which serves for frictional clamping of an outer side of the workpieces. In this case, it is an advantage that a hollow profile can be held by the inner clamping unit and the outer clamping unit in such a way that it is not deformed or compressed undesirably.

Furthermore, it may be expedient for the inner clamping unit to have a first clamping finger and a second clamping finger, which are provided with their contact surface directed outwards for contact with an inner face of the part and which is arranged a wedge element between the two clamping fingers, so that the distance between the two contact surfaces of the clamping fingers can be adjusted by axial displacement of the wedge element by means of an adjustment means. The advantage is that an internal clamping unit configured in this way has a simple structure and can apply the highest possible clamping force to the workpiece, while taking advantage of the limited space available.

Furthermore, it may be envisaged that the outer clamping unit has a first clamping finger and a second clamping finger, which are provided with their inwardly directed contact surface for contact with an outer side of the workpiece, and that a wedge element is arranged outside each of the two clamping fingers, the distance between the two contact surfaces of the clamping fingers being adjustable by axial displacement of the wedge elements by means of adjustment. The advantage in this case is that an external clamping unit configured in this way has a simple structure and can apply the highest possible clamping force to the workpiece, while taking advantage of the limited space available.

Furthermore, a spring element can be provided between the two clamping fingers of the external clamping unit, by means of which a restoring force is exerted on both clamping fingers. The advantage in this case is that the spring element presses the two clamping fingers of the external clamping unit and thus allows them to be easily returned to their initial position.

According to a special feature, it is possible that both the first and second clamping heads have a compression spring, by means of which the workpiece can be placed in the center between the two heads before the clamping heads are closed. The advantage in this case is that this means that the workpiece does not have to be positioned exactly in the center of the stretch bending machine to be picked up, but rather that when the two clamping heads are moved towards each other, the workpiece The work can first rest on one of the two heads and then, by the forward movement of the two clamping heads, the workpiece is centered by the uniform distribution of pressure on the pressure springs of the two heads.

According to an advantageous refinement, provision can be made for a first bearing support to be formed on the machine frame, on which the undeformed workpiece can be placed, the first bearing support being movable in the vertical direction, and which A second support bracket is formed on the machine frame, on which the deformed workpiece can be placed, the second support bracket can be moved in a vertical direction. In this way it can be achieved that the workpiece can be inserted into the support bracket and does not have to be held by the machine operator for the clamping process.

In particular, it may be advantageous if the pressure die has a pressure die upper part and a pressure die bottom part, the two pressure die parts forming an insert slot with a slot base and two slot walls. facing each other, each of which is configured in a pressure die part, and wherein the part can be received in the insertion slot and the distance of the two pressure die parts in relation to each other can be adjusted by means adjustment, so that the two walls of the groove can move closer to each other. An advantage here is that by means of the two parts of the pressure piston, which can move relative to each other, the formed profile can be crushed after the deformation process has finished, so that any bulge can be pressed out. profile.

It can also be provided that the two clamping devices have a coarse adjustment whereby the distance between the clamping devices can be adjusted approximately to the length of the workpiece. The advantage of this is that the stretch bending machine can be used for workpieces of different lengths.

Furthermore, it may be provided that the clamping head of the clamping device can be adjusted between 50 mm and 1000 mm, in particular between 100 mm and 500 mm, preferably between 150 mm and 250 mm in relation to the motor mount. An advantage here is that the clamping head can be adjusted within a sufficiently large range and can be made as small as possible.

Also advantageous is a characteristic according to which the pressure die of the printing device can be adjusted between 50 mm and 2000 mm, in particular between 100 mm and 1000 mm, preferably between 200 mm and 300 mm in relation to the motor support. An advantage here is that the pressure die can be adjusted over a large enough range and can be made as small as possible.

According to the invention, there is provided a method of deformation of a workpiece using a stretch bending machine described above. The procedure comprises the following process steps:

• Placing a workpiece on the stretch bending machine;

• Movement of the two clamping heads towards each other until the workpiece can be clamped on the first side on the first clamping head and on the second side on the second clamping head;

• Clamping of the piece in the two clamping heads;

• Application of a pulling force in the direction of the workpiece by means of the two clamping heads;

• Displacement of the pressure die of the pressure device transversely to the pulling direction and therefore deforming the workpiece;

• Simultaneous movement of the two clamping heads, during the movement of the pressure die, so that the deformation of the part is compensated;

• Opening of the clamping heads after completing the deformation process;

• Separation of the two clamping heads and, with it, release of the workpiece;

• Removal of the workpiece from the stretch bending machine, each of the two clamping devices comprising an electric motor, in particular a servomotor, to adjust the clamping head and thus apply a pulling force to the workpiece.

The advantage of the process according to the invention is that the workpiece can be manufactured with a high degree of precision and the deformation parameters can be precisely maintained during the workpiece deformation process.

In addition, it may be desirable that the tensile force applied to the workpiece by means of the two clamping heads is selected such that the workpiece is subjected to a stress of between 5% and 100%, in in particular between 20% and 95%, preferably between 70% and 80% of the yield point of the workpiece. The advantage in this case is that a tensile force in the specified range of the yield point of the workpiece means that the workpiece can be easily deformed and that the internal stresses of the workpiece can be kept as low as possible. after the deformation process.

Furthermore, it may be provided that the necessary tensile force is calculated by storing the geometry of the workpiece and the strength properties of the same. It is advantageous that the necessary tensile force can be calculated with this measure and can therefore have an exact value.

Alternatively, it is conceivable that tension is applied to the workpiece and that the amount of the tensile force is not specified as a parameter, but that the workpiece is stretched to a certain% value of its initial length. In this way, the yield point of the workpiece can be set independently of the cross-sectional area of the workpiece.

Furthermore, it may be provided that the tensile force actually applied to the workpiece is determined by measuring the motor current and thus determining the torque of the electric motors of the clamping device. The advantage of this measure is that the actually applied tensile force can be determined easily and with sufficient precision.

Alternatively, external measurement sensors may be provided to determine the actual tensile force applied to the part.

According to a special feature, it is possible that the movement of the two clamping heads is synchronous during the deformation process, whereby the center of the part is kept in the center of the pressure die by active distance control. The advantage in this case is that during the deformation process, the center of the workpiece is kept in the center of the pressure die and thus a uniform deformation of the workpiece can be achieved.

According to an advantageous development, it can be provided that during the deformation process the rotating unit of the clamping device can rotate freely relative to the base unit of the clamping device and is rotated by the workpiece. It is advantageous here that this measure causes the clamping head to exert a pure tensile force on the workpiece and no bending moment is introduced into it.

In particular, it may be advantageous if, after the deformation process is completed and after the two clamping heads have moved away from each other, the rotation unit of the clamping device is rotated back to a clamping position by means of the clamping device actuator. The advantage here is that this action moves the stretch bending machine back to its initial position, thus preparing it to receive a new workpiece.

It can also be provided that the first support bracket moves upward in the vertical direction to insert the workpiece into the stretch bending machine and that the first support bracket moves downward after the workpiece has been clamped. on the clamping heads. The advantage here is that this measurement allows the workpiece to be easily inserted into the stretch bending machine.

Furthermore, it can be provided that after the completion of the deformation process and before opening the clamping heads, the second support moves vertically upwards and serves to clamp the workpiece. The advantage here is that when the clamping heads are opened the workpiece can be placed directly into the stretch bending machine.

Another advantage is a feature according to which the upper and lower parts of the pressure die can be provided to move relative to each other after completing the deformation process in order to be able to press any bulges in the workpiece. In this way, any bulge in the workpiece resulting from the deformation process can be smoothed out.

Alternatively, provision may be made for the upper part of the pressure die and the lower part of the pressure die to be held in a clamping position moving towards each other during the deforming process and to separate after the deforming process is completed to release the workpiece. The advantage of this variant embodiment is that the workpiece has already been held in shape or position several times during the deformation process and that, once the deformation process has been carried out, the workpiece can be easily removed from the pressure die. and with little effort.

All linear guides described in this document are configured as ball bearing guides in the shown embodiments. However, it is also conceivable that the linear guides are configured, for example, in the form of drag guides, such as dovetail guides.

All the screw drives described in this document are designed as ball screw drives in the illustrated embodiments. However, it is also conceivable that the spindle drives are made as normal adjusting threads, such as trapezoidal threads.

The electric motors described in this document are preferably servo motors. However, all other types of electric motors can also be used if they are equipped with the corresponding control system.

The forces appearing in the various adjusting units of the clamping and pressure devices, i.e.

Electric motors, due to deformation of the workpiece can be registered, for example, by controlling the motor current and therefore the motor torque of the individual electric motors. As an alternative, it is also possible for force sensors or torque sensors, for example, to directly measure the forces that are produced.

Electric motors can be equipped with internal position sensors by means of which the position of the components to be driven can be calculated through the angle of rotation of the electric motor. What Alternatively, the position of the components to be actuated can be directly registered by means of the displacement sensors.

It can also be provided that the electric motors are coupled to a reducer.

0046] Furthermore, provision may be made for the clamping heads to be configured to be able to rotate relative to a horizontal axis. In this way, it is possible to generate a torsion in the workpiece, in addition to the bending caused by the pressing die. In particular, provision may be made that the clamping heads can be driven by a rotary drive and that the torque can be actively adjusted.

It can also be convenient if the printing die has a variable width. This can be achieved, for example, by dividing the pressure die with respect to its width and allowing the two side halves of the pressure die to move relative to each other. In this way, the bending position of the workpiece can be varied or different versions of it can be produced.

Furthermore, it may be provided that the inner clamping unit is configured to seal the hollow profile and that a medium can be introduced into the hollow profile by means of the stretch bending machine, for example, in order to be able to apply an overpressure to the hollow profile. The medium can be, for example, a gas or a liquid, such as hydraulic oil. In this way it can be achieved that during the deformation process dents in the workpiece are avoided. In addition, the medium can be preheated or cooled to be able to apply a certain temperature to the part.

It may also be provided that heat or cold can be applied locally to the workpiece by means of a heating or cooling device arranged in the stretch bending machine. This can be done, for example, by means of a gas burner that is directed at the workpiece in the area of the bending point of the workpiece. Furthermore, it is also conceivable that such a heating or cooling device is formed in the pressure die. The heating or cooling device can also be realized in the form of a coil for induction heating. The heating or cooling device can locally influence the microstructure of the workpiece. This may be necessary especially in the area of the deformation point.

Detection means, in particular optical detection means, such as a camera or laser, may also be provided to detect the position of the workpiece. By means of this position recognition, the workpiece can be seated in the correct position on the clamping heads of the stretch bending machine. Furthermore, the detection device can be used to check the actual deformation of the part during the deformation process.

Furthermore, provision may be made for a core to be inserted into the cavity of a workpiece, especially a hollow profile, before the deformation process starts. Here it is advantageous for the part to be supported from the inside when using the core, which is inserted into the cavity. This prevents deformations of the wall thickness of the work piece.

For a better understanding of the invention, it is explained in more detail by means of the following figures.

Each of them is shown in a very simplified schematic representation:

FIG. 1 is a perspective view of a first embodiment of a stretch bending machine;

FIG. 2 another perspective view of the first embodiment of a stretch bending machine;

FIG. 3 is a perspective view of an exemplary embodiment of a pressure die of the stretch bending machine;

FIG. 4 is a perspective view of an embodiment of a clamping device of the stretch bending machine;

FIG. 5 another perspective view of the exemplary embodiment of the clamping device of the stretch bending machine;

FIG. 6 is a perspective view of an embodiment of a rotating unit of the clamping device of the stretch bending machine;

Fig. 7 a sectional view of the clamping head according to section line VN-VII of Fig. 6;

FIG. 8 a schematic representation of a first embodiment of a core for supporting the workpiece;

FIG. 9 a schematic representation of a second embodiment of a core to support the workpiece.

It should be noted as an introduction that in embodiments that are described differently, identical parts are provided with identical reference symbols or identical component designations, whereby the disclosures contained throughout the description may be likewise transferred to identical parts with Identical reference symbols or identical component designations. Furthermore, the positional information selected in the description, for example, top, bottom, side, etc., is related to the figure directly described and shown and this positional information must be transferred to the new position in case of a position change.

Figures 1 and 2 each show a perspective view from different angles of an embodiment of a stretch bending machine 1 for deformation of workpieces 2, in which the same reference symbols or designations are used. of components for identical parts. The following description is based on an overview of Figures 1 and 2.

The stretch bending machine 1 comprises a machine frame 3 on which a first clamping device 4 with a first clamping head 5 and a second clamping device 6 with a second clamping head 7. The first clamping head are arranged 5 serves to clamp and fix a first side 8 of the workpiece 2 and the second clamping head 7 serves to clamp and fix a second side 9 of the clamping piece 2. The clamping devices 4, 6 are arranged at a distance 10 from each other, whereby the distance 10 corresponds approximately to a length of the workpiece 2.

Preferably, the stretch bending machine 1 is used to deform workpieces 2 which have a longitudinal extension and are configured, for example, in the form of bars, flat bars, tubes, hollow sections and the like. In the present exemplary embodiment, the workpiece 2 is made in the form of a hollow profile, which therefore has an inner face 11 and an outer face 12, which define the thickness of the wall of the hollow profile.

The first clamping head 5 and the second clamping head 7 not only serve to clamp the workpiece 2, but can also move in the pulling direction 13, allowing a tensile stress to be applied to the workpiece 2. The direction of the pull 13 is parallel to the longitudinal direction of the workpiece 2.

The first clamping head 5 and the second clamping head 7 can be engaged in the clamping devices 4, 6, so that for workpieces 2 of different configuration clamping heads 5, 7 of different configuration can be accommodated in the clamping devices. clamping 4, 6.

Furthermore, a pressure device 14 with a pressure die 15 is provided, which is also arranged on the machine frame 3.

In an alternative embodiment variant, it can also be provided that the first clamping device 4, the second clamping device 6 and the pressing device 14 are mounted directly on the floor of a building and, therefore, the frame of the building. Machine 3 can be omitted and replaced by the floor of the hall or another base.

The pulling direction 13 is parallel to the longitudinal direction of the workpiece 2.

The pressure die 15 can be displaced in a pressure direction 16 transverse to the pulling direction 13. Preferably, it is provided that the various components, in particular the first clamping device, the second clamping device 6 and the pressure device 14 are arranged in the stretch bending machine 1 in such a way that both the pulling direction 13 and the pressing direction 16 lie in a horizontal plane and are arranged at right angles to each other.

By adjusting the pressure piston 15 in the pressure direction 16 and pressing it onto the workpiece 2, it can be deformed in the stretch-bending machine 1 under a simultaneous tensile load.

For clarity, Figures 1 and 2 show the workpiece 2 both in the undeformed initial position, where it is straight, and in its bent shape after the bending process is completed.

In order to adapt the first clamping device 4 or the second clamping device 6 to the workpieces 2 of different lengths, provision can be made for a coarse fit 17 to be formed between the clamping devices 4, 6 and the machine frame 3 In the simplest case, the coarse adjustment 17 can be made in the form of a row of holes, which is arranged in the frame of the machine 3 and corresponds to the corresponding counter holes of the clamping devices 4, 6. Depending on the Holes selected to insert the fixing means between the clamping devices 4, 6 and the machine frame 3, the distance 10 between the clamping devices 4, 6 may vary. It is preferable that the clamping devices 4, 6 are arranged at an equal distance from the center 18 of the pressure die 15. In this way, it is possible to align the center 19 of the workpiece 2, or the respective longitudinal center of the workpiece. work 2, with the center 18 of the pressure die 15.

The pressure die 15 of the pressure device 14 is preferably coupled to a linear guide 20, through which it is arranged in the frame of the machine 3 so that it can move in the pressure direction 16. In particular, it can be provided that the linear guide 20 is configured in the form of a circulating ball bearing guide, a guide rail 21 can be provided, which is fixed to the frame of the machine 3 and cooperates with a guide carriage 22. In particular, it can be provided that two of the guide rails 21 are formed, which are arranged at a distance from each other on the machine frame 3, and that a pressure die seat 23 is formed, to which two guide carriages 22 are fastened per each rail guide 21. Therefore, a total of four guide carriages 22 can be attached to the pressure die seat 23.

The pressure die 15 can be coupled to the seat of the pressure die 23, so that different pressure dies 15 can be used for differently configured workpieces 2.

Furthermore, provision may be made for the pressure die shoulder 23 to be coupled to an adjustment means 24, by which the pressure die 15 can be moved between a retracted rest position and an advanced deformation position. If the pressure die 15 is in the retracted rest position, a straight and distortion-free workpiece 2 can be inserted between the first clamping device 4 and the second clamping device 6.

As can be seen particularly well in Fig. 1, it can be provided that the adjusting means 24 of the pressure device 14 is realized in the form of a ball screw drive 30. In particular, it can be provided that a circulation nut balls 31 is attached to the seat of the pressure die 23 and that a circulating ball screw 32 is mounted on a motor support 33 of the pressure device 14. The motor support 33 of the pressure device 14 is coupled in a position fixed to the frame of the machine 3. In addition, an electric motor 34 is provided to drive the circulating ball screw 32, which can optionally be coupled to a reducer 35. The electric motor 34 is preferably also fixed or arranged on the motor bracket 33. Thus, the pressure die 15 can be moved horizontally in the pressure direction 16 by driving or rotating the electric motor 34.

Furthermore, provision can be made for the formation of a first bearing support 25 on the machine frame 3, into which the workpiece 2 to be machined can be inserted and clamped. Preferably, it is envisaged that the first support support 25 can be moved in the vertical direction 27 by means of adjustment means 26. In this way, after the workpiece 2 has been collected in the clamping devices 4, 6, the first Support support 25 can be moved downwards and therefore unhooked to allow free deformation of the part. This frees the workpiece 2 for the deformation process.

Similarly, a second bearing support 28 may be provided, which serves to hold the workpiece 2 in the deformed state. The second support bracket 28 can also be adjusted in the vertical direction 27 by means of an adjustment device 29 between a retracted position and a raised support position.

Both the first support bracket 25 and the second support bracket 28 can have a number of individual support elements that are arranged at a distance from each other.

A perspective view of the pressure die 15 with the pressure die seat 23 is shown in Fig. 3, in which the same reference symbols or component designations are used for identical parts as in Figures 1 and 2 above. In order to avoid unnecessary repetition, reference is made to the detailed description in Figures 1 and 2 above.

In Fig. 3, the guide carriages 22, which are arranged on the pressure die seat 23, are clearly visible.

As can also be seen in Fig. 3, it may be provided that the pressure die 15 comprises an upper pressure die part 36 and a lower pressure die part 37. The pressure die parts 36, 37 may form an insert slot 38 in which the workpiece 2 can be accommodated.

Such an insertion slot 38 can also be formed, for example, in a one-piece pressure die 15.

The insertion slot 38 has a slot base 39, which is bounded by a slot wall 40 of the upper pressure die 36 and by a slot wall 41 of the lower pressure die 37. In particular, it may be provided that the dies upper 36 and lower 37 pressure plates can be displaced relative to each other, so that a distance 42 between the two pressure die parts 36, 37 can be set within a predefined setting range. The distance 42 is preferably indicated as the normal distance between the wall of the groove 40 of the upper pressure die 36 and the wall of the groove 41 of the lower pressure die 37. In other words, adjusting the two parts of the pressure die 36 , 37, the distance between the two walls of the groove 40, 41 and therefore the width of the groove can be varied. In particular, provision may be made for an adjustment means 43 to be formed which serves to adjust the two pressure die parts 36, 37 relative to each other. The adjusting means 43 may, for example, be configured in the form of a hydraulic cylinder of a pneumatic cylinder or other unit, such as an electric motor with a spindle drive or an electric motor with an eccentric shaft.

In the present exemplary embodiment it is provided that two adjustment means 43 are provided, which are arranged at a certain distance from each other and serve to adjust the pressure die parts 36, 37. The embodiment of two adjustment means 43 has the following: The advantage is that, on the one hand, the possible compressive force that can be applied can be increased and, on the other, the compressive force can be guided symmetrically on the walls of the grooves 40, 41.

To adjust the two pressure die parts 36, 37 relative to each other, provision may be made that either the upper part of the pressure die 36 or the lower part of the pressure die 37 is rigidly coupled to the seat of the pressure die. 23 and the other pressure die part 36, 37 is movable relative to the rigidly coupled pressure die part.

In another alternative embodiment, provision can also be made for the pressure die parts 36, 37 to be coupled to each other by means of a mechanism, both parts of the pressure die moving synchronously towards each other or moving away from each other. . In this way, the two walls of the grooves 40, 41 can be made to fit equally in the workpiece 2.

The groove walls 40, 41 can be used during the deformation process to prevent bulging in the workpiece or it can be provided that any bulges in the workpiece are smoothed out by moving the slot walls 40, 41 relative to each other.

As shown below in Fig. 3, the pressure die 36 can be divided into a left pressure die part and a right pressure die part, so that the width 86 of the pressure die can be variably adjusted. pressure 36.

Furthermore, it may be provided that a detection means 87 is configured to detect the workpiece before and / or during and / or after the deformation process.

It may also be provided that by means of a heating or cooling device 88, arranged in the stretch bending machine 1, heat or cold can be applied locally to the workpiece 2.

In Figures 4 and 5, the first clamping device 4 is shown in two perspective views from two different directions, using the same reference symbols or component designations for identical parts as in previous Figures 1 and 2 To avoid unnecessary repetition, reference is made to the detailed description in Figures 1 and 2 above.

The individual components of the first clamping device 4 are described by an overview of Figures 1, 2, 4 and 5. As can be seen with particular clarity in Figure 1, the first clamping device 4 and the second clamping device 6 are constructed in the same way, so the second clamping device 6 is just a mirror version of the first clamping device 4. For the sake of brevity, only the first clamping device 4 is described in Figures 4 and 5 It is clear to the skilled person how the individual components of the first clamping device 4 are to be arranged in the second clamping device 6 in a mirror-like manner.

As can be seen in Figs. 4 and 5, it may be provided that the clamping device 4, 6 has a base unit 44, which is rigidly coupled to the frame of the machine 3, preferably through clamping means. The base unit 44 may be designed in one piece, for example, in the form of a welded component with several components welded together. Of course, the individual components of the base unit 44 can also be attached to each other by fixing means.

In another alternative embodiment, provision can also be made for the base unit 44 to be designed as a one-piece casting.

Base unit 44 can accommodate a rotatable unit 45, which can be rotated relative to base unit 44 with respect to axis of rotation 46. Axis of rotation 46 is preferably vertically aligned. In particular, provision can be made for the rotary unit 45 of the clamping device 4, 6 to be accommodated or supported on an upper side 47 of the base unit 44 and on a lower side 48 of the base unit 44.

In a first exemplary embodiment, provision can be made for there to be a rotary bearing 49 configured in the upper part 47 or in the lower part 48 of the base unit 44.

In an alternative embodiment variant, it can be provided that there are bolts arranged both on the upper side 47 and on the lower side 48 of the base unit 44 and that the rotary bearing 49 is formed in the rotary unit The rotary bearing 49 for the rotary reception of the rotary unit 45 relative to the base unit 44 can be realized by means of ball bearings or by means of sliding bearings.

It can also be provided that the rotary unit 45 is coupled to an actuator 50, by means of which the rotary unit 45 can be actively rotated relative to the base unit 44. The actuator 50 can be coupled to the rotary unit 45 by means of a lever 51 and can thus serve to initiate a rotational movement in the rotary unit 45.

The actuator 50 is formed by an electric motor that serves directly or indirectly to initiate the rotational movement in the rotary unit 45.

As can be clearly seen in Figures 4 and 5, it can be provided that the base of the rotary unit 45 is formed by a motor bracket 52. All components installed on the rotary unit 45 can be fixed to the motor bracket 52. The motor bracket 52 is rotatably arranged in the base unit 44 of the clamping device 4, 6.

Like the base unit 44, the motor bracket 52 can also be configured in one piece or in one piece in different embodiments.

As can be clearly seen in Fig. 5, a linear guide 53 can be configured, by means of which the clamping head 5, 7 is accommodated in the motor bracket 52 so that it can move linearly. Analogously to the linear guide 20 of the pressure device 14, two guides 54 can be arranged on the motor support 52, with each of which two guides 55 cooperate, which are arranged on the clamping head 5, 7.

Furthermore, an adjusting device 56 is provided, by which the clamping head 5, 7 can be actively linearly displaced relative to the motor support 52. The adjusting device 56 can, for example, include an actuator drive. spindle. In particular, a ball screw drive 57 may be provided to adjust the clamping head 5, 7. The ball screw drive 57 may include a ball circulating nut 58, which is rigidly attached to the clamping head 5 , 7. Furthermore, a ball screw 59 can be provided, which cooperates with the ball flow nut 58.

The ball screw drive 59 can be mounted on a spindle bearing 60, which is rigidly coupled to the motor bracket 52. Furthermore, an electric motor 61,62 can be provided to drive the ball screw drive 59. The electric motor 61, 62 can be coupled to the ball screw drive 59 by means of a reducer 63.

Fig. 6 shows a perspective view of a variant embodiment of the rotary unit 45 without illustration of the base unit 44. For clarity, Fig. 6 also does not show the adjustment means 56, in particular the electric motor 61 , 62 and the ball screw drive drive 57 for adjusting the clamping head 5, 7.

As can be seen in Fig. 6, it may be provided that an upper shaft journal 64 and a lower shaft journal 65 are housed in the motor bracket 52, cooperating with the rotary bearing 49 provided in the base unit 44. The upper shaft stump 64 may preferably be made in such a way as to serve to accommodate the lever 51 to which the actuator 50 is coupled. The two shaft stumps 64, 65 can preferably be coupled to the motor bracket 52 by means of clamping means. fixation.

In Fig. 6 it is also evident that the clamping head 5, 7 may have an internal clamping unit 66, which serves to clamp the inside 11 of the workpiece 2. Furthermore, the clamping head 5, 7 may have an external clamping unit 67 which is used to clamp the exterior 12 of the workpiece 2.

Furthermore, a compression spring 68, which is symbolically shown in Fig. 6, can be provided and is arranged in the clamping head 5, 7, whereby the compression spring 68 acts in the tension direction 13 and serves to center workpiece 2.

Fig. 7 shows a sectional view of the clamping head 5, 7 according to the section line VII-VII in Fig. 6 As can be seen in Fig. 7, the inner clamping unit 66 has a first finger clamp 69 and a second clamp finger 70. The first clamp finger 69 has a contact surface 71 which is directed outwardly. The second gripping finger 70 has a contact surface 72, which is also directed outwardly. The contact surfaces 71,72 of the clamping fingers 69, 70 are used for frictional connection or for frictional reception with the interior 11 of the workpiece 2. Between the two clamping fingers 69, 70 is arranged a wedge member 73, which can be adjusted in the adjustment direction 74 with respect to the gripping fingers 69, 70.

In particular, a distance of 75 of the contact surfaces 71, 72 of the two clamping fingers 69, 70 of the inner clamping unit 66 can be adjusted by means of an adjustment device 76. In the present example of In this embodiment, it may be provided that the adjusting means 76 is configured to move the wedge element 73 in the adjusting direction 74. The adjusting means 76 may be realized, for example, in the form of a hydraulic cylinder or a cylinder tire. By displacing the wedge element 73 or by means of the wedge surfaces formed between the wedge element 73 and the clamping fingers 69, 70, the two clamping fingers 69, 70 can be separated and thus the distance 75 between the surfaces can be adjusted. contact 71, 72 of the clamping fingers 69, 70. An increase in the distance 75 can be achieved by pulling the wedge element 73 in a direction away from the workpiece 2. A reduction of the distance 75 can be achieved by pushing out the wedge member 73. The spring stiffness of the clamping fingers 69, 70 is used to displace the clamping fingers 69, 70 relative to each other when the wedge member 73 is pushed out.

The external clamping unit 67 may also have a first clamping finger 77 and a second clamping finger 78. The two clamping fingers 77, 78 have contact surfaces 79, 78 that are facing each other and serve to clamp the outer side. 12 of workpiece 2.

Also with the external clamping unit 67, the distance between the two contact surfaces 79, 80 can be adjusted by means of adjustment means 82. Analogously to the internal clamping unit 66, it can be provided that a wedge element 83, or in this case two wedge elements 83, are arranged outside the two clamping fingers 77, 78 of the outer clamping unit 67, which can adjust the distance 81 of the contact surfaces 79, 80 of the outer clamping unit 67 by displacement in the adjustment direction 77 through the corresponding wedge surfaces. For this, the wedge elements 83 of the outer clamping unit 67 are coupled to the adjusting means 82 of the outer clamping unit 67.

Furthermore, a spring element 84 may be provided which presses the two clamping fingers 77, 78 of the outer clamping unit 67 and thus holds them in their open position or serves to readjust the two clamping fingers 77, 78 when opened.

The wedge surfaces between the wedge elements 83 and the clamping fingers 77, 78 can be configured such that when the wedge elements 83 are pushed forward towards the workpiece 2, the clamping fingers 77, 78 of the outer clamping unit 67 are moved towards each other and thus the workpiece 2 can be clamped. When the wedge elements 83 are removed, the clamping fingers 77, 78 may be separated again due to the force exerted by the spring element 84.

In addition, a stopper 85 can be formed on the inner clamping unit 66 or on the outer clamping unit 67, which serves as a depth stop for the workpiece 2.

Both the contact surfaces 71, 72 of the inner clamping unit 66 and the contact surfaces 79, 80 of the outer clamping unit 67 may have micro-serrations or the like to increase friction and thus the clamping force.

Furthermore, lubrication grooves may be provided in the individual sliding surfaces of the wedge elements 73, 83, which serve to supply lubricant to the sliding surfaces in order to minimize wear. Accordingly, various greasers can be provided on the inner clamping unit 66 and the outer clamping unit 67.

Based on an overview of Figures 1 to 7, the following part of the description explains the procedure for deforming the workpiece 2 using the stretch bending machine 1.

In a first step of the process, the workpiece 2, which is straight and undeformed, is placed on the stretch bending machine 1. In this case, provision can be made for the first support 25 to move upwards and thus serve to clamp the workpiece 2.

The clamping heads 5, 7 can then be moved symmetrically towards each other in the pulling direction 13 in order to be able to insert the workpiece 2 into the clamping head 5, 7. The compression spring 68 arranged in the heads Clamping heads 5, 7 can be used to ensure that a workpiece 2 that is not inserted centrally 100% remains centered when the clamping heads 5, 7 move towards each other, so that the center 19 of the workpiece Work 2 is aligned with the center 18 of the pressure die 15.

Then, the inner closure unit 66 and the outer closure unit 67 of the two clamping heads 5, 7 can be closed to clamp the workpiece 2 in the clamping heads 5, 7.

After clamping the workpiece 2 in the two clamping heads 5, 7, the first support bracket 25 can be moved downwards and thus disengaged to allow a free deformation of the workpiece 2 by means of the punching die. pressure 15.

Following or parallel to the previous step, the two clamping heads 5, 7 can be symmetrically moved away from each other in the pulling direction 13 and thus a pulling force can be applied to the workpiece 2.

Then, the pressure die 15 can be moved in the pressure direction 16 towards the workpiece 2 and deformed. During this deformation process the total length of the workpiece 2 is shortened due to its deformation. Therefore, it is necessary that the clamping heads 5, 7 yield in the direction of the center 18 of the pressure die 15 to maintain a certain tensile force.

In particular, provision may be made for the clamping heads 5, 7 to move in such a way that the center 19 of the workpiece 2 remains in the center 18 of the pressure die 15 during the bending process.

Furthermore, during this process the clamping heads 5, 7 can rotate freely in the respective clamping devices 4, 6 so as not to apply a bending moment to the workpiece 2, but to apply a pure tensile force to the workpiece. work 2 on your first side 8 or on your second side 9.

During the deformation process, the workpiece 2 can be collected in the insertion slot 38 of the pressure die 15. It may be provided that the walls of the slot 40 or 41 serve to stabilize the workpiece 2 or to avoid bulges in workpiece 2.

As already described, it is possible that the walls of the grooves 40, 41 are kept at a predetermined distance 42 from each other during the entire forming process or that the distance 42 between the two walls of the grooves 40, 41 is only reduced after the deformation process is completed and thereby the workpiece 2 is pressed into shape.

The two walls of the grooves 40, 41 are then separated from each other, thus increasing the distance 42, thus releasing the workpiece 2.

Parallel to this or later, the clamping units 66, 67 of the clamping heads 5, 7 can be opened and thus the workpiece 2 can be released.

The second support bracket 28, which serves to support the finished formed part, can then be moved upward.

The clamping heads 5, 7 can then be moved away from the workpiece 2 so that they are no longer engaged in the workpiece 2.

The workpiece 2 therefore rests on the second support bracket 28 and can be removed from the stretch bending machine 1.

To prepare for the reception of a new workpiece 2, the second support bracket 28 can be moved downward and the first support bracket 25 can be moved upward to receive the new workpiece 2. At the same time, the die pressure pad 15 can be moved to its initial position. At the same time, the clamping heads 5, 7 can be moved to their initial position by means of the actuator 50.

Figure 8 shows a schematic representation of a first embodiment of a core 89. The core 89 has several core segments 90, which are joined together by a connection 91. By segmenting the core 89, it is flexible in its extension longitudinal and can be adapted to the flexure of the workpiece 2. The connection 91 of the individual core segments 90 can be made by means of a leaf spring, for example. Alternatively, the individual core segments 90 can also be joined by cables.

In particular, it is foreseen that the core 89 is inserted into the hollow profile 2 before the folding process. During the bending process, the core 89 is used to ensure that the cross section of the workpiece 2 is maintained to a certain extent and that it does not buckle or bend. When the bending process is finished, the core 89 can be removed again from the workpiece 2.

Fig. 9 shows another embodiment of a core 89. As can be seen in Fig. 9, it may be envisaged that the core 89 is used for example to bend open profiles, such as a C profile. In this case, It may be provided that the core 89 has corresponding recesses into which the leg (s) of the workpiece 2 are inserted. During the bending process, the legs of the workpiece 2 are guided and thus Both can be protected against buckling.

For the sake of order, it should be noted as a conclusion that, for a better understanding of the structure, the elements have been represented partly out of scale and / or increased and / or reduced in size.

Reference symbols list

Claims (27)

1. Stretch bending machine (1) for deformation of workpieces (2), comprising stretch bending machine (1) a machine frame (3); a first clamping device (4) with a first clamping head (5) for clamping a first side (8) of the workpiece (2), the first clamping device (4) being arranged on the frame of the machine (3) ; a second clamping device (6) with a second clamping head (7) for clamping a second side (9) of the workpiece (2), the second clamping device (6) being arranged at a distance (10) of the first clamping device (4) on the machine frame (3) and the two clamping heads (5, 7) being configured to apply a traction force in the tension direction (13) to the workpiece ( two ); a pressure device (14) with a pressure die (15) to deform the workpiece (2), the pressure device (14) being arranged on the machine frame (3) between the first clamping receiver ( 4) and the second clamping receiver (6), the pressure die (15) being configured to apply a compression force in a compression direction (16) transverse to the pulling direction (13), the two clamping devices being clamping (4, 6) configured to be flexible with respect to the application of the pulling direction (13), characterized in that the two clamping supports (4, 6) each comprise an electric motor (61, 62), in particular a servomotor, to adjust the clamping head (5, 7) and thus apply a traction force to the part working (2). 2. Stretch bending machine according to claim 1, characterized in that the electric motor (61, 62) of the clamping device (4, 6) is coupled, in particular with the interposition of a reduction gear (63), to a thread of fit, in particular to a ball screw drive (57), the electric motor (61,62) being seated on a motor bracket (52) and the clamping head (5, 7) mounted on the motor bracket ( 52) by means of a linear guide (53) movable relative to it, the ball screw drive (57) being configured to introduce a linear adjustment and an adjustment force into the clamping head (5, 7). 3. Bending machine for drawing according to one of claims 1 to 2, wherein the pressure die (15) is arranged adjustably on the machine frame (3) by means of an electric motor (34), in particular a servomotor, received state the electric motor (34) on a motor support (33) which is coupled to the machine frame (3) and the pressure die (15) is mounted on the machine frame (3) of adjustable manner with respect to the motor mount (52) by means of a linear guide (20), wherein an adjustment thread, in particular a ball screw drive (30), is configured to introduce a linear adjustment and a force adjustment in the pressure die (15) and is coupled to the electric motor (34) of the pressure device (14), in particular with the interposition of a reduction gear (35). 4. Bending machine for drawing according to one of the preceding claims, wherein the clamping device (4, 6) comprises a base unit (44) which is coupled to the machine frame (3) and has a rotating unit (45) , which is mounted on the base unit (44) so that it can rotate with respect to a rotation axis (46), where the electric motor (61, 62) together with the motor support (52) and also the head Clamping units (5, 7) are included in the rotating unit (45) and together can rotate with respect to the base unit (44) of the clamping receiver (4, 6). 5. Bending machine for drawing according to claim 4, wherein the rotating unit (45) of the clamping device (4, 6) is coupled to an actuator (50), in particular a hydraulic cylinder or a pneumatic cylinder, whereby The rotating unit (45) can be actively rotated relative to the base unit (44). 6. Bending machine for drawing according to one of the preceding claims, characterized in that the clamping head (5, 7) is configured to receive workpieces (2) are designed as hollow profiles, wherein an indoor unit holder (66 ) is configured to forcibly hold an inner side (11) of the workpieces (2) and wherein an outer clamping unit (67) is configured to forcibly clamp an outer side (12) of the workpieces (2). 7. Bending machine for drawing according to claim 6, characterized in that the inner clamping unit (66) having a first finger (69) and a second finger (70) with its contact surface facing outwards (71, 72), are intended to come into contact with an inner side (11) of the workpiece (2), and in that a wedge element (73) is arranged between the two clamping fingers (69, 70 ), it being possible to adjust the distance (75) between the two contact surfaces (71, 72) of the clamping fingers (69, 70) by moving the wedge element (73) by means of an adjustment means (76). 8. Bending machine for drawing according to claim 6 or 7, characterized in that the outer holding unit (67) having a first finger (77) and a second finger (78) connected to its contact surface directed inwardly (79, 80) to come into contact with an outer side (12) of the workpiece (2), and because outside each of the two gripping fingers (77, 78) a clamping element is arranged wedge (83), it being possible to adjust the distance (81) between the two contact surfaces (79, 80) of the clamping fingers ⁽ 77 ⁾ by axial displacement of the wedge elements (83) by means of adjustment means (82). 9. Bending machine for drawing according to claim 8, characterized in that a spring element (84) is arranged between the two gripping fingers (77, 78), through which a restoring force in both gripping fingers exerted ( 77, 78). 10. Bending machine for drawing according to one of the preceding claims, characterized in that both the first clamping head (5) and the second clamping head (7) having a compression spring (68) whereby the workpiece (2 ) can be arranged centered between the two clamping heads (5, 7) before the clamping heads (5, 7) are closed. 11. Bending machine for drawing according to one of the preceding claims, characterized in that the machine frame (3) comprises a first support bracket (25), on which can be placed the workpiece undeformed (2) , the first support support (25) being able to move in the vertical direction (27), and because a second support support (28) is formed on the machine frame (3), on which the workpiece can be placed deformed (2), the second support support (28) being able to move in a vertical direction (27). 12. Bending machine for drawing according to one of the preceding claims, wherein the pressure die (15) has a die portion higher pressure (36) and a lower die part pressure (37), forming the two parts of pressure die (36, 37) an insert slot (38) with a slot base (39) and two slot walls (40, 41) facing each other, which are each formed into a pressure die part ( 36, 37), and where the work piece (2) can be collected in the insertion slot (38) and where the two pressure die pieces (36, 37) can be adjusted to each other at their spacing (42 ) by means of adjustment (43), so that the two walls of the groove (40, 41) can move towards each other. 13. Bending machine for drawing according to one of the preceding claims, characterized in that the two clamping devices (4, 6) have a coarse adjustment (17) by which the distance (10) of the clamping devices (4, 6) each other can be adjusted approximately to the length of the workpiece (2). 14. Bending machine for drawing according to one of the preceding claims, characterized in that the clamping head (5, 7) of the clamping device (4, 6) can be set between 50 mm and 1000 mm, in particular between 100 mm and 500 mm, preferably between 150 mm and 250 mm, relative to the motor support (52). 15. Bending machine for drawing according to one of the preceding claims, wherein the pressure die (15) of the pressure device (14) is adjustable between 50 mm and 2000 mm, in particular between 100 mm and 1000 mm, preferably between 200 mm and 300 mm, in relation to the motor support (52). 16. Process for deforming a workpiece (2) using a stretch bending machine (1) according to one of the preceding claims, wherein the process comprises the following process steps: - introducing a workpiece (2) into the stretch bending machine (1); - move the two clamping heads (5, 7) relative to each other until the workpiece (2) can be clamped on the first side (8) on the first clamping head (5) and on the second side (9) on the second clamping head (7); - clamping the workpiece (2) in the two clamping heads (5, 7); - application of a traction force in the direction of traction (13) to the workpiece (2) by means of the two clamping heads (5, 7); - moving the pressing die (15) of the pressing device (14) transversely to the pulling direction (13) and thus deforming the workpiece (2); - while moving the pressure die (15), simultaneously moving the two clamping heads (5, 7) to compensate for the deformation of the workpiece (2); - open the clamping heads (5, 7) after the deformation process has been completed; - move the two clamping heads (5, 7) away from each other and thus free the workpiece (2); - remove the workpiece (2) from the stretch bending machine (1), characterized in that the two clamping devices (4, 6) each comprise an electric motor (61, 62), in particular a servomotor, to adjust the clamping head (5, 7) and thus apply a traction force to the part working (2). 17. Method according to claim 16, wherein the tensile force applied to the workpiece (2) by means of the two clamping heads (5, 7) is selected such that the workpiece (2) is subjected to a tension of between 5% and 100%, in particular between 20% and 95%, preferably between 70% and 80% of the yield point of the workpiece (2). 18. Process according to claim 16 or 17, characterized in that the tensile force required is calculated based on the geometry of the workpiece (2) and the strength properties of the workpiece (2). 19. Process according to one of claims 16 to 18, characterized in that the tensile force actually applied to the workpiece (2) is determined by measuring the current of the motor and thereby determining the torque of the electric motors (61, 62) of the clamping device (4, 6). 20. Process according to one of claims 16 to 19, wherein the displacement of the two clamping heads (5, 7) is synchronous during the deformation process, keeping the center (19) of the workpiece (2) the center (18) of the pressure die (15) by active control of the trajectory. 21. Process according to one of claims 16 to 20, characterized in that during the deformation process the rotating unit (45) of the clamping device (4, 6) can be oriented freely with respect to the base (44) drive device clamping (4, 6) and is rotated by the workpiece (2). 22. Process according to one of claims 16 to 21, characterized in that, once the deformation process and after the distance of the two clamping heads (5, 7), the rotating unit (45) of the clamping device (4 , 6) is rotated again in the reception position by means of the actuator (50) of the clamping device (4, 6). 23. Method according to one of claims 16 to 22, characterized in that in order to insert the workpiece (2) into the stretch bending machine (1), the first support support (25) is moved upwards in the vertical direction (27) and after clamping the workpiece (2) in the clamping heads (5, 7) the first support bracket (25) is moved downwards. 24. Method according to one of claims 16 to 23, characterized in that after the end of the deformation process and before the opening of the clamping heads (5, 7), the second support support (28) moves upwards by vertical direction (27) and serves to receive the workpiece (2). 25. Process according to one of claims 16 to 24, characterized in that the top of the pressure die (36) and the bottom of the pressure die (37) move toward each other after the deformation process is completed to be able to press the possible bulges of the piece (2). 26. Method according to one of claims 16 to 25, characterized in that the upper part of the pressure die (36) and the lower part of the pressure die (37) are held in a clamping position offset towards each other during the process deformation and separate from each other after the end of the deformation process to release the workpiece (2). 27. Process according to one of claims 16 to 26, characterized in that before the beginning of the deformation process a core (89) is introduced into the cavity of a workpiece (2) which is designed especially as a hollow profile.