Transfer device, cyclically working workpiece processing machine having a transfer device, and method for operating a transfer device

Abstract

The invention relates to a transfer device (12), to a workpiece processing machine (10) having a transfer device (12), and to a method for operating the transfer device (12). The transfer device (12) is arranged on a machine frame (14) of the workpiece processing machine (10) and has gripper carriers (30) which can be moved translationally relative to the machine frame (14) in a longitudinal direction (x), a transverse direction (y), and a working direction (z) and which are designed to hold at least one workpiece (11) and to move same between at least two positions (A, B, C). A vibration (Vn) occurs on the machine frame (14) in the working direction (z), which can impair the positioning accuracy of the gripper carriers (30). Therefore, according to the invention, a compensation signal (zkn) is to be calculated for a current working cycle of the workpiece processing machine (10) on the basis of a vibration signal (OSn-m) of a preceding working cycle (n-m) and a predetermined target carrier position (zsn) is to be modified based on the compensation signal (zkn). A positioning deviation of the gripper carriers (30) in the working direction (z) is minimised or eliminated in this way.

Description

Schuler Presses GmbH, December 3, 2024 Schuler-Platz 1 SUPR P265 WO prrn 73033 Göppingen Keyword: Vibration compensation on the transfer beam Transfer device, cyclically operating workpiece processing machine with a transfer device, and methods for operating a transfer device

[0001] The invention relates to a transfer device for a cyclically operating workpiece processing machine, a cyclically operating workpiece processing machine with a transfer device, and a method for operating a transfer device. The cyclically operating machine tool can be, for example, a machine for forming a workpiece and / or for separating parts from a workpiece. The workpiece processing machine can be, for example, a forming press, forging press, punching machine, or similar. In particular, the cyclically operating workpiece processing machine has a ram that is translationally movable in a working direction between two reversal points, and on which a tool or a tool part for workpiece processing is arranged.

[0002] Such cyclically operating workpiece machining machines, in particular workpiece machining machines with a ram movable in the working direction, machine one workpiece during each work cycle. The workpiece machining can take place in the workpiece machining machine in a single machining stage or in several successive machining stages. In the latter case, for example, several tools or several tool components can be arranged on a movable ram. to machine a workpiece step by step in successive work cycles. The machining of a single workpiece can be carried out in each work cycle with one of the tools or one of the tool parts, and the workpiece can then be transported further for further machining with another tool or tool part in a subsequent work cycle.

[0003] During such cyclical operation of a workpiece processing machine, accelerations and machining forces occur that cause vibrations in the machine's frame. If a transfer device is supported directly or indirectly by the machine frame, the vibrations caused by the workpiece processing machine can cause positional deviations of the transfer device, thus impairing the safe picking up and dropping of a workpiece.

[0004] The transfer device for transferring or transporting at least one workpiece has a transfer drive to move a gripper or manipulator and to move a workpiece between two or more than two positions. For example, an initial workpiece can be fed in and inserted into a tool. After machining, the workpiece can be removed from the tool and either inserted into another tool for a further machining stage or transported away.

[0005] It is known, for example, from DE 10 246 093 CI, to dampen mechanical vibrations of a drive axis of a machine or robot. For this purpose, feedback elements are provided in the control loop of the drive axis, to which The actual velocity of the drive axle is supplied as an input signal, with each feedback element being tuned to a specific vibration frequency range of the drive axle to be damped. The feedback elements can, for example, be configured as bandpass filters to suppress vibrations. The signals provided by the feedback elements are then used to control the rotational speed of a motor on the drive axle. In this way, the vibrations caused by the drive axle during its movement can be reduced.

[0006] DE 10 204 016 731 Al proposes to provide additional microactuators to dampen excitations of critical natural frequencies.

[0007] Based on the prior art, the object of the present invention can be considered to be to improve the positional accuracy of a transfer device in a cyclically operating workpiece processing machine.

[0008] This problem is solved by a transfer device with the features of claim 1, a cyclically operating machine tool with the features of claim 12, and a method with the features of claim 15.

[0009] The transfer device has gripper carriers that are mounted on a machine frame of a cyclically operating workpiece processing machine. As mentioned at the outset, the workpiece processing machine can be a machine for forming and / or separating (e.g., cutting or punching) a workpiece in one or more processing stages. Preferably, the A workpiece processing machine is a press and / or punch with a ram mounted on the machine frame so as to be movable in one working direction. The ram can, in particular, be mounted so as to be movable translationally in the working direction. By means of a ram drive, the ram can preferably be moved between an upper reversing position and a lower reversing position, preferably reaching the lower reversing position and / or the upper reversing position at least once in each working cycle.

[0010] The working direction is preferably vertically oriented. Alternatively, it can have a different orientation and, for example, be horizontally oriented. In one embodiment, the working direction is perpendicular to a longitudinal direction and / or a transverse direction, wherein the working direction, the longitudinal direction, and the transverse direction preferably form a Cartesian coordinate system. The coordinate system is arranged in a fixed position relative to a surface on which the workpiece processing machine is placed. The coordinate system is, so to speak, stationary.

[0011] The transfer device has a transfer drive that is controlled or regulated by a transfer controller. The transfer drive is designed to move the gripper carriers translationally in a working direction relative to the machine frame. Preferably, the gripper carriers can also be moved translationally in the longitudinal and / or transverse direction by means of the transfer drive. Therefore, a workpiece can be picked up by the gripper carriers, moved in the working direction and / or longitudinal direction, and placed down again in a different position. In this way, a workpiece can be fed to and removed from the workpiece processing machine. The workpiece can be removed from the workpiece processing machine. Within the workpiece processing machine, the workpiece can also be positioned in different processing positions, for example, if the workpiece is processed sequentially in several processing stages or work cycles in different processing positions.

[0012] The transfer unit also includes a vibration detection unit. This unit is designed to detect a vibration signal characteristic of vibrations in the machine frame in the direction of operation. The vibration signal can describe the temporal progression of the vibration during a work cycle, particularly over the entire work cycle. The vibration signal can be a measured value, such as a vibration detected by a vibration sensor. Alternatively, the vibration signal can also be determined based on a sensor signal and / or known or predefined parameters, specifically through simulation, calculation, and / or estimation, optionally employing machine learning.

[0013] The transfer control unit used to control the transfer drive specifies a target position for the gripper carriers in at least one spatial direction (e.g., working direction) during a work cycle. This target position varies over time during a work cycle. For example, the gripper carriers are moved between two positions in at least one spatial direction (e.g., working direction), such as to pick up, lift, or place down a workpiece.

[0014] The transfer control modifies the target position of the beam based on a compensation signal. This compensation signal is, in turn, determined based on the vibration signal. For example, the compensation signal can be the inverted vibration signal, so that the sum of the vibration signal and the compensation signal is zero. Using the compensation signal and the target position of the beam, a compensated target position is determined and used to control the transfer drive when moving the beam in at least one spatial direction.

[0015] The transfer control system is configured to use the vibration signal from one of the preceding work cycles, specifically the vibration signal from the immediately preceding work cycle, when determining the compensation signal for the current work cycle. Thus, at the beginning of each current work cycle, the time course of the compensation signal for the entire current work cycle is already available and can be used to modify the target position of the support.

[0016] Therefore, a compensated target position for the current work cycle is obtained, which can be used without additional time delay for controlling or regulating the movement of the gripper carriers in at least one spatial direction (especially the working direction). The compensated target position is available, so to speak, in real time. An actual signal feedback for determining a current compensation signal and the associated time delays are eliminated. In this way, vibrations introduced from the workpiece machining center into the transfer drive via the machine frame can be at least partially, and ideally completely, compensated. Essentially, all deviations are completely compensated, so that no or only minor positional deviations of the gripper carriers occur in at least one spatial direction. One or more workpieces can be safely picked up and placed down.

[0017] In a preferred embodiment, the gripping arms extend parallel to each other in the longitudinal direction and are spaced apart in the transverse direction. When a workpiece is gripped, the space between them is reduced in the transverse direction, while it is increased to release the gripped workpiece. Preferably, the gripping arms are arranged at the same level when viewed in the working direction and are therefore located in a common plane oriented perpendicular to the working direction. In the working direction and longitudinal direction, the gripping arms are positioned and / or moved identically. In the transverse direction, the gripping arms can be moved in opposite directions to each other.

[0018] The gripper carriers can be set up to pick up several workpieces simultaneously, move them to a new position and put them down.

[0019] Preferably, a vibration signal is determined in each work cycle. The last measured vibration signal is then used to determine the compensation signal in at least one subsequent work cycle. If the workpiece processing machine operates with a constant cycle duration or stroke rate after a start-up or readjustment (steady-state operating condition), it may be sufficient not to measure the vibration signal and / or compensation signal in each work cycle, but for example, only in every second, third, fourth, or generally xth work cycle (with the natural number x>2 ).

[0020] The vibration signal can be detected during a work cycle, for example, using a vibration sensor. The vibration sensor can be configured to detect a continuous signal or to detect a vibration signal value at discrete times during a work cycle. The vibration sensor could, for example, be an accelerometer.

[0021] In addition to or as an alternative to sensor-based detection of the vibration signal, the vibration signal can also be calculated based on at least one known parameter and / or at least one predetermined setpoint and / or at least one measured actual value. For example, a force acting on the workpiece during machining and an acceleration of a tool used for machining the workpiece or of a ram of the workpiece processing machine can be measured or otherwise determined. The acceleration can, for example, be calculated from a trajectory known through the control system of the workpiece processing machine.From the force and the acceleration, a vibration signal can then be determined, for example by means of an algorithm, a function, a characteristic curve, a characteristic map, a table or a determined relationship, which can be determined empirically and / or by simulation.

[0022] In a preferred implementation form, the course of the magnitude of the compensation signal corresponds to each The timing of the vibration amplitude or the magnitude of the vibration signal is used to determine the compensation signal. This allows the compensated target position to be obtained by simple subtraction or addition from the target position. Preferably, the compensation signal corresponds to the inverted (multiplied by -1) vibration signal used to determine it.

[0023] A cyclically operating workpiece processing machine according to the present invention can have any embodiment of a transfer device as described above. In particular, the cyclically operating workpiece processing machine has a ram mounted on the machine frame, movable in the working direction between an upper reversal position and a lower reversal position, which can be moved translationally in the working direction by means of a ram drive. The ram drive can, in particular, be controlled such that the ram is moved according to a predetermined motion sequence during each working cycle. During this motion sequence, the ram, in particular, assumes its lower reversal position at least once and its upper reversal position at least once.

[0024] Using any of the above-described exemplary embodiments of a transfer device, the following procedure can be carried out:

[0025] A vibration signal is determined that is characteristic of a vibration at the machine frame in at least one spatial direction – in particular at least in the working direction – preferably in each work cycle or at least repeatedly in some of the work cycles. By means of The transfer control system specifies a target position for the gripper carriers of the transfer device in at least one spatial direction. Based on the vibration signal determined during a previous work cycle, a compensation signal is generated for the current work cycle, for example, by inverting the vibration signal. The target position is then modified based on the compensation signal, for example, by adding or subtracting it. The result is a compensated target position, which can then be used to control or regulate the transfer drive via the transfer control system to move the gripper carriers in at least one spatial direction (preferably the working direction).

[0026] Advantageous embodiments of the invention will become apparent from the dependent claims, the description, and the drawing. Preferred embodiments of the invention are explained in detail below with reference to the accompanying drawing. The drawing shows:

[0027] Figure 1 shows a schematic representation of an exemplary embodiment of a cyclically operating workpiece processing machine, designed as a press,

[0028] Figure 2 shows a schematic representation of an embodiment of a transfer device with two gripper carriers in a top view in the working direction.

[0029] Figure 3 shows a block diagram of an embodiment of a control system for the position or movement of the gripper carriers in the working direction.

[0030] Figure 4 is a schematic representation of a railway- Course of motion for a ram of the workpiece processing machine from Figure 1 and a vibration occurring on the machine frame in the working direction,

[0031] Figure 5 shows the path from Figure 4, the path of a target position and an actual height position of the gripper beams during a work cycle and

[0032] Figure 6 shows an exemplary progression of the actual height position of the gripper beams through the use of the compensation according to the invention compared to a temporal progression without compensation according to the invention of the target beam position.

[0033] Figure 1 shows a highly schematic, block-like diagram of a cyclically operating workpiece processing machine 10 for machining workpieces 11. The workpiece processing machine 10 is specifically designed to reshape a workpiece 11 and / or to cut and / or punch parts of it. In each work cycle of the workpiece processing machine 10, at least one workpiece 11 is fed in an initial state and at least one workpiece 11 is removed in a machined (e.g., reshaped) state. For this purpose, the workpiece processing machine 10 has a transfer device 12 (see also Figure 2).

[0034] In the embodiment shown in Figure 1, the cyclically operating workpiece processing machine 10 is configured as a press 13 for forming the workpieces 11. Therefore, the invention will be explained below, without limiting the generality, using the example of the press 13, whereby all features also apply to other cyclically operating machines. The workpiece processing machines 10 can be used, which are explained in connection with the press 13.

[0035] When the index "n" is used with a reference symbol in the description, the reference symbol j refers to the current work cycle n. Similarly, the index "nm" refers to a previous work cycle nm.

[0036] The press 13 has a machine frame 14 which is placed on a base 15 (for example, a foundation). Spring and / or damping elements 16 can be used to support the machine frame 14 on the base 15, as shown schematically in Figure 1.

[0037] On the machine frame 14, a ram 17 of the press 13 is mounted in a working direction z according to a predetermined movement sequence H. n (Figures 4 and 5) of the respective work cycle are movable. For the movement of the plunger. The press 13 has a controllable ram drive 18, for example an eccentric drive or another suitable ram drive 18. The ram drive 18 is controlled by a press control 19. 18 can, for example, include an electric motor (not shown), in particular a servo motor, which is controlled by means of the press control 19.

[0038] For the forming of workpiece 11, the press 13 a press tool with a lower tool part 20 and an upper tool part 21 on . The lower tool part 20 is, for example, fixed to the machine frame. 14 arranged. The upper tool part 21 is arranged, for example, on the ram 17. For forming, a workpiece is ii between the two tool parts 20, 21 by a force F applied by the plunger 17 n (here: pressing force) processed and reshaped as an example. The force F nThe force can optionally be determined by means of a force sensor 22 and transmitted to the press control 19. The press 13 can optionally be equipped with further sensors for recording current operating parameters of the press 13, for example, a position sensor 23 to determine the current position of the ram 17 in the working direction z and / or a speed sensor (not shown) to determine the speed of an electric motor of the ram drive 18. All sensor signals can be transmitted to the press control 19.

[0039] In the preferred embodiment, the workpiece processing machine 10 formed by the press 13 has a vibration sensor 24 arranged on the machine frame 14. The vibration sensor 24 can, for example, be an acceleration sensor. The vibration sensor 24 is configured to detect a vibration V occurring on the machine frame 14 in at least one spatial direction and, for example, in the working direction z. nto detect and generate a corresponding vibration signal OS n to generate the oscillation signal OS. n It serves to control the transfer device 12, as will be explained later.

[0040] In the simplest case, a vibration detection unit 25 can be used to determine the vibration V n characteristic oscillation signal OS n The vibration sensor 24 may be formed by the vibration sensor. Alternatively, the vibration detection unit 25 may include a processing unit 26 and optionally at least one additional sensor. The processing unit 26 is configured to process the vibration signal OS. n based on a given context (to -is- (e.g., algorithm, function, characteristic curve, map, table or any combination thereof) to determine, for which the computing unit 26 can use at least one sensor signal and / or known parameters (e.g., unchanging parameters, variables, setpoints, etc.).

[0041] The working direction z is specifically vertically oriented. Perpendicular to the working direction z and perpendicular to each other, a longitudinal direction x and a transverse direction y form a Cartesian coordinate system, which is defined as immobile with respect to the ground 15.

[0042] In the present example, the vibration in the working direction z is detected and at least partially compensated, as described below. In other embodiments, the vibration can additionally or alternatively be detected and at least partially compensated in the longitudinal direction x and / or in the transverse direction y.

[0043] For workpiece transfer, the press 13 has the transfer device 12. The transfer device 12 has two gripping carriers 30 extending in the longitudinal direction x. The gripping carriers 30 are arranged at a distance from each other in the transverse direction y. On the sides facing each other in the transverse direction y, gripping elements 31 are arranged on each gripping carrier 30, by means of which a workpiece 11 arranged in the transverse direction y between the gripping carriers 30 can be held force-fit and / or form-fit for workpiece transfer. The gripping elements 31 can have recesses open to the workpiece 11, for example, groove-like recesses, so that they can grip an associated edge area on the workpiece 11 in the working direction z on opposite sides.

[0044] The gripper carriers 30 can also be referred to as "transfer beams". The gripper carriers 30 are translationally movable relative to the machine frame 14 in the longitudinal direction x, the transverse direction y, and the working direction z. For this purpose, the transfer device 12 has a transfer drive 33 controlled by a transfer controller 32. The transfer drive 33 can have an individually controllable drive axis or drive unit 33x, 33y, 33z for each direction x, y, z, as shown schematically in Figure 1.

[0045] During operation, the gripper carriers 30 are moved synchronously to each other in the longitudinal direction x and in the working direction z at all times, such that they occupy the same position in both directions. Only in the transverse direction y are the gripper carriers 30 moved in opposite directions, so that they either move towards each other or away from each other in the transverse direction y. This opposing movement of the gripper carriers 30 allows workpieces 11 positioned between them to be grasped by the gripper elements 31 (movement of the two gripper carriers 30 towards each other) or allows held workpieces to be released (movement of the two gripper carriers 30 away from each other).

[0046] In the embodiment of press 13 shown here, a workpiece 11 is machined and, for example, formed in a single machining step during each work cycle. Press 13 could also have several upper tool parts 21 and several lower tool parts 20 to machine a workpiece 11 in multiple stages in successive work cycles. The transfer of the workpiece 11 between the different press stages The transfer device 12 can take over, analogous to the illustrated example of the single-stage press 13.

[0047] In the exemplary embodiment, the workpieces 11 are moved from a starting position A to a machining position B in the press 13 (between the tool parts 20, 21) and, after machining, from machining position B out of the press 13 to a storage position C. During each work cycle, one workpiece 11 can be moved from the starting position A to the machining position B and simultaneously another workpiece 11 can be moved from the machining position B to the storage position C. The feeding of a workpiece 11 into the starting position A and the removal of formed workpieces from the storage position C can be carried out by means of a transport device, for example a conveyor belt or other known transport devices.

[0048] To execute the movement in the longitudinal direction x and in the transverse direction y, the gripper carriers 30 are arranged to be linearly displaceable in the longitudinal direction x and in the transverse direction y on a transfer slide 34 of the transfer device 12. The transfer slide 34 is mounted on the machine frame 14 so as to be linearly movable in the working direction z (Figure 2).

[0049] As illustrated by example in Figure 1, the press control 19 and the transfer control 32 can be interconnected via communication or integrated in the form of control modules in a common control system.

[0050] The workpiece processing machine 10, explained in this respect with reference to the press 13, as well as the transfer equipment- The operation of the 12 units is explained below with reference to Figures 3 to 6. As already mentioned, reference symbols are given the index n when they refer to the current work cycle. Accordingly, an index n-1 denotes the immediately preceding work cycle, and an index nm denotes any previous work cycle.

[0051] Figure 4 schematically shows an exemplary sequence of movements H. n for the current work cycle n is illustrated. A work cycle begins at an initial time ta and ends at an end time te (cycle duration TC). The end time te of a work cycle corresponds in turn to the initial time ta of the following work cycle. It can be assumed that the plunger 17 is in an upper reversal position OT at the beginning and at the end of the work cycle. According to the movement path H nThe ram 17 is moved from the upper reversal position OT towards the lower tool part 20 and comes into contact with a workpiece 11, which is inserted between the two tool parts 20 and 21, at a contact time tw. During the subsequent further movement of the ram 17, the workpiece is formed until the ram 17 reaches a lower reversal position UT at a reversal time tu. After the reversal time tu, the ram 17 moves away from the lower tool part 20 back to the upper reversal position OT.

[0052] Acceleration of the ram 17 in the working direction z and the impact of the ram 17 or the upper tool part 21 on the workpiece 11 generates rapidly changing forces which must be supported by the machine frame 14, resulting in a vibration V n in the Each current work cycle forms a vibration on the machine frame 14 in the working direction z. Figure 4 shows such a vibration V. n This oscillation V is illustrated as an example for a current work cycle n. n However, this impairs the positioning accuracy of the gripper carriers 30 and the gripper elements 31 arranged on them in the working direction z, in order to be able to securely grip the workpiece 11 or workpieces for workpiece transfer and place them in a positionally accurate manner. This is particularly important because the workpieces 11 are gripped at their edge regions by a force-locking and / or form-locking movement of the gripper carriers 30 towards each other and are thus held and transported. This requires precise positioning of the gripper carriers 30 in the working direction z.

[0053] To ensure precise positioning of the gripper carriers 30 in the working direction z, the vibration V occurring on the machine frame 14 is n The deficiencies are determined and at least partially, or ideally completely, compensated for. The procedure is as follows:

[0054] The vibration V occurring on the machine frame 14 in the working direction z n is detected by means of the vibration detection device 25, for example the vibration sensor 24, and this vibration V is recorded. n descriptive oscillation signal OS n This oscillation signal OS is generated. n can preferably be generated in each work cycle. However, it may also be sufficient to generate the vibration signal OS. n to be determined repeatedly in work cycles that do not follow each other immediately.

[0055] In the exemplary embodiment, the vibration signal OSn is determined by means of the vibration sensor 24, wherein the sensor signal the vibration signal 0S n represents. Additionally or alternatively, the vibration signal 0S can be generated based on the sensor signal and / or known parameters. n in the vibration detection device 25 and in particular the processing unit 26. For example, at least one sensor signal, such as the force F, can be transmitted to the processing unit 26. n during the processing and, for example, reshaping of the workpiece 11. Based on the movement sequence H n and / or the position or movement of the plunger 17 detected by the position sensor 23, a plunger acceleration can be determined. The acting forces and accelerations are characteristic of the resulting oscillation V. n, whereby this relationship depends on specific design parameters of the press 13 or the machine frame 14 and can be determined, for example, by simulations, empirically by tests, or by machine learning. The relationship can be stored in the computing unit 26 in the form of an algorithm, a function, a characteristic curve, a characteristic map, or a table, or in another suitable way, in order to derive the vibration signal 0S from it. n to determine.

[0056] Based on this oscillation signal OS n The transfer control 32 can be set up, which is the control for the height position shown in the block diagram in Figure 3. n to execute the gripper carrier 30. For this purpose, the vibration signal OS is used. n-m a previous work cycle nm and, for example, the immediately preceding work cycle n-1 is used to generate a compensation signal zk nto generate for the current work cycle n. In the example given, the vibration signal OS is used for this purpose. n -i from the previous work cycle is inverted by means of an inverter 40 and used as a compensation signal zk n for the The current duty cycle n is used. The sum of the compensation signal zk n for the current duty cycle n and the vibration signal OS n -i of the previous work cycle n-1 is therefore equal to zero.

[0057] It should be noted at this point that the oscillation signal OS n-m the vibration V occurring on the machine frame 14 n-m The entire cycle duration TC of the respective work cycle nm, from the start time ta to the end time te, describes a temporal progression. The compensation signal zk is analogous to this. nFor each current work cycle n, a temporal progression is already present at the beginning of the respective current work cycle n, since zk serves as a compensation signal. n a vibration signal OS n-m The data used is already known from one of the previous work cycles and is therefore available. A time delay in the control of the actual height position zi n The gripper carrier 30 in the respective current work cycle n can be avoided in this way.

[0058] As illustrated in the block diagram of Figure 3, the compensation signal zk n for the current work cycle to a target carrier position zs n the gripper carrier 30 added and thereby a compensated carrier target position zsk n received. The target carrier position zs n is predefinable for each point in time during a work cycle n in the transfer control 32.

[0059] The compensated carrier target position zskn The actual regulation of the current altitude position is then carried out. n The gripper carrier 30 is used. For this purpose, the difference between the compensated carrier target position and the tion zsk n and the current altitude position n determined in the current work cycle and from this the position deviation Az n The position deviation is then fed to a controller 41, which can be implemented, for example, as a PD controller or a PID controller. Based on the position deviation Az, the controller 41 outputs n a controller output signal za n from , which is formed to determine the positional deviation Az n to reduce and ideally eliminate. The controller output signal za n The signal is transmitted to the transfer drive 33 and, for example, to the drive unit 33z, which is configured to move the gripper carriers 30 in the working direction z. The height position zi nis changed until the position deviation Az n sufficiently small or equal to zero.

[0060] Figure 5 illustrates the movement of the gripper carriers 30 during a work cycle. The gripper carriers 30 are moved in the working direction z between a lowered position zl and a raised position zr in the working direction z. At the beginning of the current work cycle n, the gripper carriers are in the raised position zr and hold at least one workpiece 11. In this position, the gripper carriers 30 can move the at least one workpiece 11 longitudinally x between two successive workpiece positions, for example, from the starting position A to the machining position B and / or from the machining position B to the storage position C.

[0061] At a first time tl, the movement of the gripper carriers 30 begins from the raised position zr to the lowered position zl, which is reached at a second time t2. From the second time t2, the gripper- The carrier 30 is moved away from each other in the transverse direction y to release at least one workpiece 11. A workpiece 11 placed in the machining position B in this way is then machined and, for example, formed.

[0062] After a workpiece 11 has been released in the lowered position zl, the gripper carriers 30 can be moved back to a starting position in the longitudinal direction.

[0063] When the ram 17 with the upper tool 21 is moved back towards the upper reversal position OT after the reversal time tu, the two tool parts 20, 21 move away from each other, creating a space to grip and pick up the workpiece 11 in the machining position B by means of the gripper carriers 30 or the gripper elements 31. From a third point in time t3, the two gripper carriers 30 are therefore moved towards each other in the transverse direction y in order to pick up (and hold) the at least one workpiece 11 arranged between them by friction and / or positive locking. If the gripper carriers 30 hold the at least one workpiece 11 in a force-locking and / or form-locking manner, the movement from the lowered position zl to the raised position zr can then start at a fourth time t4, whereby the raised position zr is reached at a fifth time t5 .In the raised position zr, the gripper carriers 30 can again be moved in the longitudinal direction x in order to move at least one workpiece 11 accordingly between the different positions.

[0064] Figure 6 shows a time period from a current work cycle n and illustrates an example the target position of the carrier zs n and the current altitude position nThe gripper carrier 30. As can be seen, the vibration of the gripper carrier 30 in the vertical direction z, which originates from the machine frame 14 and is transmitted to the transfer device 12, cannot be completely compensated, but can be significantly reduced. This is shown by comparison with the comparison curve K. The comparison curve K represents the actual vertical position of the gripper carrier 30 if no compensation of the vibration were to take place. It can be seen that, particularly in a critical time period from the third time t3, when the gripper carriers 30 are moved towards each other in order to grip at least one workpiece 11, without compensation there would be a very high deviation between the comparison curve K and the target position zs of the carrier. n This occurs. Through the vibration compensation according to the invention, this deviation can be significantly reduced, which is evident from the comparison of the actual height position. n compared to the target position of the carrier zsn Figure 6 shows .

[0065] As already explained, compensation of the support position, for example with regard to the working direction z, can also be carried out additionally or alternatively in another spatial direction (longitudinal direction x and / or transverse direction y) if a vibration in the relevant direction is detected.

[0066] The invention relates to a transfer device 12, a workpiece processing machine 10 with a transfer device 12, and a method for operating the transfer device 12. The transfer device 12 is arranged on a machine frame 14 of the workpiece processing machine 10 and has gripper carriers 30 that are translationally movable relative to the machine frame 14 in a longitudinal direction x, a transverse direction y, and a working direction z. which are designed to hold at least one workpiece 11 and move it between at least two positions A, B, C. A vibration V occurs on the machine frame 14 in the working direction z. n on, which can impair the positioning accuracy of the gripper carriers 30. Therefore, according to the invention, a compensation signal zk is provided. n to calculate for a current work cycle of the workpiece processing machine 10, based on a vibration signal OS n-m a previous work cycle nm and a predetermined carrier target position zs n based on the compensation signal zk n to modify. A positioning deviation of the gripper carrier 30 in the working direction z is thereby minimized or eliminated. Reference character list: 10 workpiece processing machines 11 Workpiece 12 Träns t er einrichtung 13 Press 14 machine frame 15 Subsurface 16 Spring and / or damper element 17 pestles 18 plunger drive 19 Press control 20 lower tool part 21 upper tool part 22 Force sensor 23 Position sensor 24 vibration sensor 25 Vibration detection unit 26 computing units 30 grabber carriers 31 Gripping element 32 Träns t er Steuerung 33 Träns t er antrieb 34 Transfer slides 40 Inverter 41 regulators Az n Position deviation Starting position B Processing position C Storage position F n Power H n Movement pattern 0S n Vibration signal OT upper reversal position t time tl first time point t2 second time point t3 third time point t4 fourth time point t5 fifth time point ta starting time point TC cycle duration of a work cycle te end time tu reversal time tw contact time UT lower reversal position V n Vibration in the working direction on the machine frame x longitudinal direction y transverse direction z working direction za n Controller output signal zi n Altitude position zk n Compensation signal zl lowered position zr raised position zs n Carrier target position zsk n compensated target carrier position

Claims

Patent claims:

1. Transfer device (12) which is configured to move at least one workpiece (11) between at least two positions (A, B, C), comprising: two gripper carriers (30) movably mounted on a machine frame (14) of a cyclically operating workpiece processing machine (10), - a transfer drive (33) which is configured to move the gripper carriers (30) translationally in a working direction (z), - a vibration detection unit (25) which is configured to detect a vibration signal (OS n ) to determine what is characteristic of an oscillation (V n ) on the machine frame (14) in at least one spatial direction (x, y, z) , - a transfer control (32) which is configured to move a specified carrier target position (zs n ) in at least one spatial direction (x, y, z) for the gripper carriers (30) based on a determined compensation signal (zk)n ) to modify in order to achieve a compensated carrier target position (zsk) n ) to obtain and to use for controlling or regulating the transfer drive (33), wherein the compensation signal (zk n ) of the current duty cycle(s) based on the vibration signal (OS n-m ) at least one previous work cycle (nm) is determined.

2. Transfer device according to claim 1, wherein the gripper carriers (30) extend parallel to each other in a longitudinal direction (x), are arranged at a distance from each other in a transverse direction (y) and preferably -27- are arranged perpendicular to the working direction (z) in a common plane, wherein the longitudinal direction (x), the transverse direction (y) and the working direction (z) form a Cartesian coordinate system.

3. Transfer device according to claim 1 or 2, wherein the transfer control (32) is configured to measure the compensation signal (zk n) based on the oscillation signal (OS n -i) of the immediately preceding work cycle (n-1).

4. Transfer device according to one of the preceding claims, wherein the vibration detection unit (25) is configured to measure the vibration signal (0S) n ) to determine in such a way that it is characteristic of a time course of the oscillation (V n ) on the machine frame (14) in at least one spatial direction (x, y, z) during an entire work cycle (n) .

5. Transfer device according to one of the preceding claims, wherein the vibration detection unit (25) is configured to measure the vibration signal (0S) n ) based on the sensor signal of at least one sensor (22, 23, 24).

6. Transfer device according to one of the preceding claims, wherein the vibration detection unit (25) is configured to measure the vibration signal (0S) n) to detect using a vibration sensor (24).

7. Transfer device according to one of the preceding claims, wherein the vibration detection unit (25) is configured to measure the vibration signal (0S) n ) based on an action on the workpiece (11) Force (F n ) and the acceleration (a n ) of a tool (21) used to machine the workpiece .

8. Transfer device according to one of the preceding claims, wherein the transfer control (32) is configured to measure the compensation signal (zk). n ) to determine such that its magnitude at each time during the duty cycle (n) of the vibration amplitude of the vibration signal (0S) n-m ) of a previous work cycle (nm).

9. Transfer device according to one of the preceding claims, wherein the transfer control (32) is configured to measure the compensation signal (zkn ) by inverting the oscillation signal (0S n-m to determine.

10. Transfer device according to claim 9, wherein the transfer control (32) is configured to determine the compensated carrier target position (zsk). n ) as the sum of the target position of the carrier (zs n ) and the compensation signal (zk n to determine.

11. Transfer device according to one of the preceding claims, wherein the at least one spatial direction (x, y, z) in which the vibration signal (OS) n ) is determined, which is the direction of work (z) or has it.

12. Cyclically operating workpiece processing machine (10) comprising a machine frame (14) and a transfer device (12) according to one of the preceding claims . IS. Cyclically operating workpiece processing machine according to claim 12, further comprising a ram (17) mounted on the machine frame (14) movable in the working direction (z) between an upper reversal position (OT) and a lower reversal position (UT) and a ram drive (18) which is configured to move the ram (17) in the working direction (z).

14. Cyclically operating workpiece machining machine according to claim 13, wherein the ram drive (18) is configured to move the ram (17) during each working cycle according to a predetermined motion sequence (H n ) to move .

15. Method for operating a transfer device (12) comprising two gripper carriers (30) movably mounted on a machine frame (14) of a cyclically operating workpiece processing machine (10), a transfer drive (33), a vibration detection unit (25) and a transfer control (32), wherein the method comprises: - Determining an oscillation signal (OS) n ) , which is characteristic of an oscillation (V n ) on the machine frame (14) in at least one spatial direction (x, y, z) , - Specifying a target carrier position (zs n ) in at least one spatial direction (x, y, z) for the gripper carriers ( 30 ) , - Determining a compensation signal (zk) n ) for the current work cycle(s) based on the Oscillation signal (OS) n-m ) of a previous work cycle (nm) , -SO- Modifying the target carrier position (zs n ) based on the compensation signal (zk n ) , to achieve a compensated carrier target position (zsk n ) to obtain, - Using the compensated target carrier position (zsk n ) for controlling or regulating the transfer drive ( 33 ) . -31-

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