EP1633507A1

EP1633507A1 - Transfer device on a press

Info

Publication number: EP1633507A1
Application number: EP04735864A
Authority: EP
Inventors: Rudolf Lüthi; Theo Egolf
Original assignee: Adval Tech Holding AG
Current assignee: Adval Tech Holding AG
Priority date: 2003-06-13
Filing date: 2004-06-03
Publication date: 2006-03-15
Also published as: WO2004110667A1; US20060230809A1; JP2006527088A; CN1805806A

Abstract

The invention relates to a device and a method for gradually conveying workpieces in a longitudinal direction from a receiving station through at least one processing station of the press with the aid of conveying means for the workpieces, which are moved in cycles and in synchrony with the movement of the press in the longitudinal direction as well as back and forth in a direction extending substantially perpendicular to the longitudinal direction in order to grip or release the workpieces. The conveying means are moved in the longitudinal direction via an external drive unit that is merely synchronized with the movement of the press. In order to obtain a particularly flexible mode of operation at high numbers of lifting movements in such a device, the motor-powered external drive unit (20-24, 35-37) is mechanically coupled to the conveying means (4) in such a way that the conveying means (4) can be moved back and forth without reversing the direction of rotation of the external drive unit (23, 35).

Description

DESCRIPTION

TITLE Transfer device on a press

TECHNICAL FIELD The present invention relates to a device on a press and a method for the gradual transport of workpieces in a longitudinal direction from a receiving station through at least one processing station of the press with transport means for the workpieces, which cyclically and synchronously with the movement of the press in the longitudinal direction as well for gripping or releasing the workpieces in a substantially perpendicular transverse direction to and fro. The movement of the transport means in the longitudinal direction takes place via an external drive that is only synchronized with the movement of the press. Transfer devices are distinguished from so-called progressive composite tools in that the part to be formed in the press in the area of the receiving station is first separated, for example, from an endless strip, for example by cutting or punching, and then independently of the movement of the endless strip and mostly also perpendicularly to it by the at least one processing station is transported to the press. The press is usually provided with several processing stations or forming stages connected in series. In the case of progressive dies, on the other hand, the part to be formed is transported from the forming step to the forming step by its own endless strip from which it originates. STATE OF THE ART

Basically, one can assume two drive systems for the longitudinal drive of transfer systems.

First of all, there is the purely mechanical drive. The transfer is driven mechanically via a gear with a gear worm and a lever, the gear being driven directly from the eccentric shaft of the press via a toothed belt, a chain or a shaft. Typical cycle angles for these mechanical gearboxes are:

Feed angle = 120 ° Standstill angle after feed = 60 °

Return stroke angle = 120 °

Standstill angle after the return stroke = 60 °

Alternatively, the drive can be named via a controlled third-party system (e.g. servo motor / linear motor). The longitudinal movement is driven by a rotor of a servo motor that drives a system that generates the longitudinal movement (toothed belt with longitudinal guides / threaded roller spindle with longitudinal guides). The longitudinal movement can alternatively be generated directly by a linear motor.

Comparing these two basic approaches, the following advantages and disadvantages can be listed: Advantages of mechanical drive:

• The sequence of movements follows the given mathematical formula, which is shown in the form of the gear worm

• high accelerations can be achieved (up to 25 g)

• there are no following errors ^β the movement sequence is synchronized with the press movement at all times

• No risk of collision with the tool because the moving assemblies are mechanically coupled. Disadvantages of mechanical drive:

• Movement sequence (feed cycle) cannot be changed

• Elaborate construction for the drive from the press to the gear

• The placement of the gearbox is determined by the output of the press. • The feed path is fixed.

Advantages of servo drives

• Feed cycle can be selected flexibly (software)

• Attachment to the press is flexible

• Different cycles can be run on the press • Feed path can be changed

Disadvantages of servo drive:

• Acceleration is limited

• Following errors and overshoot during the movement

• Number of cycles limited • Mass to be moved limited in relation to the number of strokes and feed

• Drive can fail

• In order for the servo motor to move its own mass, it requires a relatively large amount of energy.

A mechanical transfer device similar to the type mentioned with a pair of transport bars as a means of transport for the workpieces is e.g. known from EP 0

490 821 Al. There the transport rods are driven by mechanical

Coupling with moving parts of the press in the longitudinal direction by reducing the movement from the eccentric shaft of the press via a gearbox and in the transverse direction by reducing the movement from the ram of the press using control rails, which enables high stroke rates in the range of 300 cycles per minute. For special Applications in the can range are even achieved up to 700 cycles per minute. The mechanical coupling also largely prevents collisions of the press tool with the means of transport.

Basically similar devices are known from EP 0 504 098 A1 and EP 0 694 350 A1, with a vertical movement being superimposed on the transport rods or the workpieces.

In addition, transfer devices are known in which the drive of the transport means is effected via one or more external drives using servomotors, hydraulics, pneumatics, linear motors, etc. and which are synchronized in various ways with the movement of the press ram in terms of signal technology. Such third-party drives are generally cheaper and also more flexible to use than the aforementioned mechanical couplings, but they cannot achieve such high stroke rates. The limit here is currently 50-150 cycles per minute. Also, if a drive fails, there is a risk of a collision between the press tool and the means of transport with mostly destructive consequences.

Another possible approach is described in WO-A-00/20305. Here is a device for the gradual transport of workpieces in a longitudinal direction from a receiving station through at least one processing station of a press with transport means for the workpieces, which cyclically and synchronously with the movement of the ram of the press in the longitudinal direction and for gripping or releasing the workpieces are moved back and forth in a perpendicular transverse direction. The transport means are driven in the longitudinal direction by an external drive, which is only synchronized with the eccentric shaft of the press in terms of signals. The movement of the transport means for releasing the workpieces in the transverse direction, however, is derived from the movement of the press ram by direct mechanical coupling. This type of drive achieves the advantages of purely mechanical drives in terms of safety and high cycle rates with the low cost and greater flexibility of third-party drives in combination. The disadvantage of this, however, is that, in comparison to a purely mechanical longitudinal movement due to the servo motor used, only comparatively low Cycle rates significantly below 300 or even only 250 strokes / minute are possible.

SUMMARY OF THE INVENTION It is therefore the object of the invention to propose an improved device on a press for the gradual transport of workpieces, which in particular enables high cycle rates in the range of those of purely mechanical longitudinal movements and which on the other hand nevertheless has the flexibility of devices using third-party drives , In particular, this relates to a device on a press for the step-by-step transport of workpieces in a longitudinal direction from a receiving station through at least one processing station of the press with transport means for the workpieces, which is cyclical and synchronous with the movement of the press in the longitudinal direction and for detecting or release the workpieces back and forth in an essentially perpendicular transverse direction, the movement of the transport means in the longitudinal direction being effected by an external drive which is only synchronized with the movement of the press.

This object is achieved in that the motor-driven external drive is mechanically coupled to the transport means in such a way that the back-and-forth movement of the transport means is possible without reversing the rotation of the external drive.

Typically, when using third-party drives, especially with servomotors, its main problem is that the achievable accelerations or stroke numbers are limited as a result of the forward and backward movement to be initiated. This back and forth in each case requires rapid braking or acceleration of the servo motor (stop and go), and since large moving masses are typically present in such a device, the possible accelerations are limited in comparison to purely mechanical solutions. The essence of the invention is therefore a mechanical coupling of the to provide motorized external drive to the means of transport, which allows the external drive to be operated without reversing the rotation, and thus to avoid, reduce or otherwise place the accelerations that are otherwise necessary, or to place them in sections where little masses are accelerated. The actual reversal of rotation is generated by a corresponding mechanical transmission that converts the back and forth movement, while the external drive, typically a servo motor, can be operated, for example, with a constant rotational speed and constant direction of rotation in the feed. This configuration results in a large number of unexpected advantages, essentially the advantages of a purely mechanical drive can be combined with those of a purely external drive.

A first preferred embodiment is accordingly characterized in that the mechanical coupling between the external drive and the transport means is designed as a mechanical gear, particularly preferably as a mechanical cam gear. For example, the use of a worm gear is possible.

A further preferred embodiment is characterized in that the movement of the external motor drive is synchronized with the movement of the press, in particular with the movement of an eccentric shaft of the press, via an angular step encoder. Such a synchronization of the external drive and the press can actually achieve lifting speeds which are comparable to those of purely mechanical transfer devices.

A particularly preferred embodiment of the present invention has means which allow the external motor drive to be operated at different speeds depending on the feed cycle ¹ . This inherent flexibility of the third-party drive allows, among other things, the change of the feed angle and thus the reshaping of higher components in the press without requiring mechanical modifications. In particular, the speed of the longitudinal movement of the transport means can be varied within certain limits without mechanical changes solely by controlling the speed of the external drive. This now without the reversal of the state of the art required Direction of rotation of the servo motor, ie at high clock rates.

A further preferred embodiment of the device according to the invention is characterized in that the movement of the transport means for releasing the workpieces in the transverse direction is derived from the movement of the press by direct mechanical coupling. The movement of the means of transport for gripping the workpieces in the transverse direction can also be carried out by an external drive, a combination of a motorized external drive with a mechanical gearbox, i.e. is possible without reversing the direction of rotation of the external drive. This is in and of itself, i.e. possibly also independent of the design of the longitudinal drive possible implementation of the transverse drive, which is new and inventive.

Another preferred embodiment of the device is characterized in that the drive of the transport means for releasing the workpieces in the transverse direction is derived from the movement of the press ram via a mechanical cam system. Furthermore, the transport means preferably comprise transport rods which extend in the longitudinal direction on both sides of the receiving and at least one processing station and which are preferably equipped with grippers for the workpieces.

Further preferred embodiments of the device according to the invention are described in the dependent claims.

Furthermore, the present invention relates to a method for the gradual transport of workpieces on a press, particularly preferably using a device as described above. Transport in a longitudinal direction from a receiving station is ensured by at least one processing station of the press with transport means for the workpieces, which is cyclical and synchronous with the movement of the press in the longitudinal direction and for gripping or releasing the workpieces in a substantially perpendicular manner Be moved back and forth. In addition, the movement of the transport means in the longitudinal direction takes place via an external drive that is only synchronized with the movement of the press. According to the invention, there and back Movement of the transport means driven by the external motor drive without reversing the rotation of the external drive. This is done in particular by using a mechanical gear which generates a back and forth movement from the rotational movement of the external drive. A first preferred mode of operation is characterized in that the external motor drive is operated at a constant speed of rotation and direction of rotation. The curve characteristic of the transmission is typically optimized for such constant operation. As an alternative, and particularly preferably, it is now possible to operate a device as described above in such a way that the external motor drive is operated at a varying rotational speed with a preferably constant rotational direction depending on the feed cycle. The flexibility of an external drive in the longitudinal direction can be combined with the high number of strokes of a purely mechanical conveying in the longitudinal direction. It is particularly preferred that the speed of rotation of the external drive is varied in those sections of the feed cycle in which the transport means do not perform any longitudinal movement (so-called standstill sections). In the other sections, ie in the feed and in the return stroke, the rotational speed of the external drive is preferably kept constant, an increased, constant rotational speed preferably being driven, for example, during the feed. In those sections of the feed cycle in which the transport means do not perform a longitudinal movement, the speed of rotation is preferably first slowed down and the speed of rotation is subsequently accelerated to the value relevant for the subsequent section of the cycle. With optimal use of the curve characteristics of the transmission (for example, designed for constant speed of the external drive), the feed angle can be reduced with regard to driving style with constant speed of rotation of the external drive. The variation of the rotational speed of the external drive in the standstill sections has the particular advantage that there are virtually no moving masses (apart from the shaft of the servo motor and the worm gear and possibly a reduction gear) and accordingly Energy losses (braking) or high energy consumption (acceleration) can be avoided. In this way, for example, stroke rates of more than 200 strokes / min or more than 270 strokes / min can be achieved. Strokes in the range of or more than 300 strokes / min or even more than 350 strokes / min are typically possible.

BRIEF EXPLANATION OF THE FIGURES

The invention will be explained in more detail below using exemplary embodiments in conjunction with the drawings. 1 shows a plan view of the table of a press with a transfer device;

Figure 2 is an end view of the press with parts of the transfer device.

3 shows a partial section along line III-III in FIG. 1 on a larger scale;

4 shows a part of the longitudinal drive of the transfer device;

5 shows a schematic illustration of the feed cycle of a mechanical transfer gear;

6 shows a schematic representation of the transfer system with variable feed time or with variable angles; and

Fig. 7 is a schematic representation of the feed cycle of a transfer operation with variable angles.

WAYS OF CARRYING OUT THE INVENTION

Figures 1 and 2 show more or less schematically a press table 1, guide columns 2 and a press ram 3. In the usual manner, the lower part is attached to the table 1 and the upper part of a so-called transfer tool with several processing or forming stations connected in series. For simplification, this tool is not shown in the drawing. As a means of transport for the workpieces to be formed in the longitudinal direction through the individual forming stations there is a transport rod 4 on both sides of the tool with grippers 5 for the workpieces, shown purely schematically. The ends of the transport rods are mounted on longitudinal slides 7 by means of fastening angles 6. The longitudinal slide 7 (Figure 3) are rigidly guided along two parallel guide rods 8, which in turn are fastened in a cross slide 9 which is guided along two parallel transverse guide rods 10.

The transverse movement of the transport rods 4 in the opening direction is controlled by control rails 11, which are mounted on the press ram 3 and act with their external control cams 12 on control rollers 13 of extensions 14 of the slide 9. On the other hand, the extensions 14 act on the piston rods 15 of pneumatic cylinders 16 in the opposite direction inwards. A reliable contact pressure in the closing direction therefore always acts inwards on the extensions 14, so that the control rollers 13 always rest securely on the control cams 12 of the control rails 11. It can be seen from FIGS. 2 and 3 that when the control rails 11 move downward with the press ram 3, the control rollers 13 and the parts connected thereto, i.e. also the transport rods 4 are spread outwards, so that a workpiece 17 clamped between two opposite holders 5 is released. The holders 5 are also laterally removed from the area of the upper and lower tool parts of the press, so that the tool for machining workpieces can close in all stations.

In FIG. 1 it is indicated that workpieces such as blanks 18 are punched out of a transverse belt 19 in a punching and receiving station and are taken over by the outermost grippers of the transport rods 4. In successive work cycles, the workpieces 18 are gradually shifted to the left and are thus fed to the individual forming stations of the transfer tool one after the other. After a certain start-up time, all the forming stations are each occupied with a workpiece 18. The transport rods 4 perform a closed rectangular movement per working cycle by advancing a number of detected blanks to the next forming station of the transfer tool in a first cycle, and laterally outwards in a second cycle Workpieces and removed from the overlap area with the tool, returned in a third cycle in the longitudinal direction and moved inwards to the tool in a fourth cycle to grasp the workpieces (see also Fig. 5, comment below). The longitudinal drive of the transport rods 4 comprises two leaf springs 20 which are attached with their right ends to the inside of the longitudinal slide 7 and which, as indicated in FIG. 4, can follow the transverse movements of the transport rods 4. At their left end, the two leaf springs 20 are connected to a longitudinally movable guide carriage 21, which is driven by an electric servo motor 23 via a toothed belt 22. The servo motor 23 is acted upon by a control signal 24, which is derived from the movement of the eccentric shaft of the press and with an angle rotary encoder (not shown).

The procedure according to the invention is now such that the advantages of a mechanical transmission are combined with the advantages of a servo drive, in that an external drive, i. H. a servo motor is used via a mechanical gearbox to generate the longitudinal drive. To a certain extent, the mechanical transmission takes over the task of generating a thrust reversal from the rotation of the motor without having to change the direction of rotation.

With a mechanical transmission there are normally 4 sectors (see Fig. 5):

• Feed sector 25 for transporting the formed part from one tool stage to the next.

Standstill sector 26 for transferring the formed part from the transfer system to the forming tool.

• Return sector 27 for returning the gripper rails to the starting position. e Standstill sector 28 for transferring the formed part from the tool to the gripper rails.

Typically, the angles of the 4 sectors can be assumed as follows: ^β feed sector 25: 120 °

• Standstill sector 26: 60 °

• Return stroke sector 27: 120 °

• Standstill sector 28: 60 ° When designing these angles, the feed angle 25 is particularly critical. The formed part has to be transported in this sector and it must not fall out of the grippers or move in it during the movement.

In addition, the size of the angle is crucial for determining the available usable height, at which formed parts can still be formed. This height, the theoretical usable height, is shown in FIG. 5 with the reference symbol 30, and the total height, the press stroke, with the reference symbol 29. The press stroke is fixed for a given arrangement.

The larger the angle, the lower the parts that are to be formed must be. With a purely mechanical coupling of the press stroke and longitudinal movement and lateral movement, both the press stroke 29 and the theoretically usable height 30 are not adjustable.

Another connection is the number of cycles of the press in connection with the feed angle. The smaller the angle, the lower the number of cycles, because otherwise the acceleration in the feed sector will be too great (mechanical accelerations of up to 25 g are possible). In the case of a transfer system with a classic servo drive, the motor must always move from zero to max. Speed accelerates and when braking max. Speed can be decelerated to zero.

If the two drive types of the transfer systems are now combined in the manner according to the invention, the following approach is used (cf. FIG. 6):

A servo motor 35 with a variable number of revolutions and an angular step encoder drives a mechanical cam mechanism 38, in which the sectors are optimized Aspects are designed for a maximum number of cycles of the press. This optimization is usually designed for constant engine speed. A reduction gear 36 can also be arranged between the servo motor 35 and cam gear 38. The servo motor 35 is an electric motor that can be switched, that is, whose output can be controlled. For example, a servo motor 35 with 3000 revolutions / min can be used, and a reduction gear 36 with a factor 1:10, so that a rotation of 300 revolutions / min is applied to the transfer gear 38.

The servo motor 35 is synchronized by a controller from an angle step sensor 32, which is driven by the eccentric shaft of the press 31. In order to ensure synchronization, the servo motor 35 also has an angle stepper.

The angle encoder is an electronic assembly that is able to divide a rotation of a shaft (e.g. eccentric shaft of the press) by 360 ° into increments of 0.044 °, for example, and calculate the respective angular position of the eccentric shaft precisely.

The transfer gear 38 comprises a gear worm 37, which from the

Rotary movement of the servo motor 35 produces a longitudinal movement. This

Longitudinal movement is transmitted to the transport rods 4 via a feed lever 34.

If one now drives with the maximum number of cycles, according to the interpretation of the curve law of the transfer gear 38, the servo motor 35 runs at a constant rate. Rotation, which corresponds exactly to the rotation of the eccentric shaft of the press 31.

In this operating mode, the system runs exactly the same as if the gear 38 were driven directly by the eccentric shaft of the press 31.

If you now want to take advantage of the servo motor 35, the number of revolutions of the motor 35 can be changed in the individual curve sectors. A variable feed time can thus be allowed with a fixed feed path 33. This is shown schematically in analogy to FIG. 5 in FIG. 7. • If the gear runs at the same number of revolutions as the press, the feed time corresponds to the designed feed angle (situation of Fig. 5).

• If the gear in the feed angle range 25 or 40 moves faster than the press, the time is shortened and the feed angle becomes virtually smaller. This increases the usable height for part forming (arrow 30 in Fig.

5). It should be noted that the usable height for part reshaping is at least twice the height of the part to be reshaped, and that typically at least one third has to be calculated for the transport.

• In the area of the standstill zones 26, 28, the number of revolutions of the servo motor 35 can be changed

If the advance angle 40 is to be reduced, the motor 35 can be brought to a higher speed within the standstill section 43 of the gear worm 37 (no longitudinal movement of the transfer). In this case, the feed angle 40 is traversed in a shorter time and virtually the angle becomes smaller. In the next sector (transfer of the formed part to the tool), the motor 35 can be decelerated again in such a way that it runs synchronously with the press 31 at the latest when entering the return stroke.

Correspondingly, for example, the movement sequence shown in FIG. 7 results with different time intervals: Starting position:

• The press is running e.g. with a nominal speed of 300 strokes / min

• The mechanical stepping gear 38 is designed for the standard angles 120 ° / 60 ° / 120 ° / 60 °. β The feed cycle (time) is compared to the standard time by e.g. 50% reduced. (virtual feed angle = 60 °).

The following sections or points are run through in the movement sequence:

1. The press is started at the top dead center 39 of the press, and reaches its nominal speed after a short time. The transfer feed sets still half of the feed path 33 back.

2. At pos. A, the feed stops while the press continues to run at constant speed. The grippers are closed in this position. When moving into the area, the grippers release as soon as the press tool has clamped the part to be machined sufficiently.

3. In area B, the servo motor 35 reduces its speed (below the speed of the press).

4. In area C, the servo motor 35 increases its speed to the nominal speed of the press.

5. At item D, the transfer feed begins its return stroke 42 and runs back to its end position item E at the same speed as the press. The actual work of the tool takes place in area 42. Accordingly, the grippers only close again at position E around the finished part.

6. In area F, the servo motor 35 reduces its speed (below the speed of the press). NB: In extreme cases the speed of the servo motor can be reduced to zero.

7. In area G, the servo motor 35 increases its speed (above the speed of the press).

8. The transfer feed 40 starts at item H. The area between items H and A is run through with increased speed of the transfer gear compared to the press speed. (e.g. double speed in the present example) By changing the speed of the servo motor 35 compared to the press speed, the cycle times of the transfer system can be adjusted individually.

In theory, it is also possible to close the entire motion cycle of the transfer gear rotate. (e.g. return stroke is at dead center 39, feed is shifted 180 °).

It should be noted that at each of the positions A, D, E and H both the angle and the speed must have a certain value. For this reason, in the standstill phases 41 and 43 there is both braking and acceleration. In summary, it can be said that the combination of a mechanical gearbox with a servo motor can be used to change the curve law of the gearbox. For example, on the one hand, higher parts can be machined, this is somewhat less quickly than in normal operation, but without the need to convert the machine. With lower parts, correspondingly larger stroke rates can be achieved and the tool's spring travel is shorter.

The system has the following advantages:

• all the advantages of the mechanical transmission

• all advantages of the servo drive with the exception of the variable feed path • servo motor does not have to run in stop and go mode and therefore requires less energy (typically a servo motor with half power can be used compared to a longitudinal drive with a servo motor without worm gear)

• The change in speed can be carried out in the standstill sector of the gear worm

• The performance of the transfer system corresponds to that of a ^' fully mechanical system

• Higher parts can be formed on a press with a fixed lifting height

• The application area of the press can be expanded and results in greater customer benefit

«If the servo motor changes the speed, it only has to accelerate or decelerate its own mass (rotor) and the mass of the gear worm, because the linearly moving mass of the transfer system is in the standstill sector, the performance of the transfer system can be increased by approx. 20 to 30% compared to a pure servo transfer.

LIST OF REFERENCE NUMBERS

1 press table

2 pillars

3 press rams

4 transport bar

5 grippers for the workpieces

6 mounting bracket

7 longitudinal slides

8 guide rods

9 cross slides

10 cross guide rods

11 control rails

12 control curves

13 steering rollers

14 extensions

15 piston rods

16 pneumatic cylinders

17 clamped workpiece

18 blank

19 belt running across

20 leaf spring

21 guide slides

22 timing belts 23 servo motor

24 control signal

25 feed (standard angle = 120 °)

26 Standstill (standard angle = 60 °) 27 Return stroke (standard angle = 120 °)

28 standstill (standard angle = 60 °)

29 press stroke, fixed

30 theoretically usable height for part forming

31 Press 32 angle encoder

33 feed path

34 feed lever

35 servo motor

36 Reduction gear 37 Gear cutting

38 transfer gears

39 Press top dead center

40 feed

41 Standstill 42 Return stroke

43 Standstill

44 axis of rotation of feed lever

Claims

1. Device on a press (1 - 3, 31) for the gradual transport of workpieces (17, 18) in a longitudinal direction from a receiving station through at least one processing station of the press with transport means (4) for the

Workpieces, which are cyclically and synchronously with the movement of the press in the longitudinal direction and for gripping or releasing the workpieces in a substantially perpendicular transverse direction back and forth, the movement of the transport means in the longitudinal direction over one with the movement of the Press (1-3, 31) only synchronized

External drive (20-24, 35-37) takes place, characterized in that the motor external drive (20-24, 35-37) is mechanically coupled to the transport means (4) in such a way that the back and forth movement of the transport means (4) is possible without reversing the rotation of the external drive (23, 35).

2. Device according to claim 1, characterized in that the mechanical coupling between external drive (23, 35) and transport means (4) as a mechanical transmission, particularly preferably as a mechanical

Cam gear (38) is formed.

3. Device according to claim 2, characterized in that the gear is a worm gear (37, 38).

4. Device according to one of the preceding claims, characterized in that the movement of the external motor drive (20-24,35-37) via an angle step encoder (32) to the movement of the press (1-3, 31), is coupled in particular to the movement of an eccentric shaft of the press (1-3, 31).

5. Device according to one of the preceding claims, characterized in that means are provided which allow the external motor drive (20-24,35-37) to be operated at different speeds depending on the feed cycle.

6. Device according to one of the preceding claims, characterized in that it is an external motor drive (23, 35)

Servomotor acts.

7. Device according to one of the preceding claims, characterized in that the movement of the transport means (4) for releasing the workpieces in the transverse direction by direct mechanical coupling from the

Movement of the press is derived.

8. Device according to one of the preceding claims, characterized in that the movement of the transport means (4) for gripping the workpieces (17, 18) in the transverse direction also by an external drive

(16) takes place.

9. Device according to one of the preceding claims, characterized in that the speed of the longitudinal movement of the transport means (4) can be varied within certain limits without mechanical changes solely by controlling the speed of the external drive (23, 35).

10. Device according to one of the preceding claims, characterized in that the drive of the transport means (4) for releasing the workpieces in the transverse direction is derived from the movement of the press ram (3) via a mechanical cam system (11, 12).

11. Device according to one of the preceding claims, characterized in that the transport means comprise transport rods (4) which extend in the longitudinal direction on both sides of the receiving and the at least one processing station and which preferably have grippers (5) for the workpieces (17 , 18) are busy.

12. Method for the gradual transport of workpieces (17, 18) on a press (1-3, 31), particularly preferably using a device according to one of claims 1-11, in a longitudinal direction from a pick-up station through at least one processing station of the press with means of transport (4) for the workpieces, which are cyclically and synchronously moved back and forth in a transverse direction essentially perpendicular to the movement of the press in the longitudinal direction and for gripping or releasing the workpieces, the movement of the means of transport in the Longitudinal direction over a synchronized only with the movement of the press (1-3, 31)

External drive (20-24,35-37), characterized in that the back and forth movement of the means of transport (4) are driven by the external motor drive (20-24,35-37) without reversing the rotation of the external drive (23,35).

13. λ ^ experience according to claim 12, characterized in that the external motor drive (23,35) is driven at a constant speed of rotation and direction of rotation.

14. The method according to claim 12, characterized in that the motor-driven external drive (23, 35) is operated as a function of the feed cycle with a varying rotational speed with a preferably constant rotational direction.

15. The method according to claim 14, characterized in that the rotational speed of the external drive (23, 35) is varied in those sections (26, 28, 41, 43) of the feed cycle in which the transport means (4) do not perform any longitudinal movement.

16. The method according to any one of claims 14 or 15, characterized in that the rotational speed of the external drive (23, 35) is varied such that the feed angle (25, 40) is reduced with respect to driving at a constant rotational speed of the external drive (23,35) ,

17. The method according to claim 16, characterized in that an increased, constant rotational speed is driven during the feed (25, 40), and that in those sections (26, 28, 41, 43) of the feed cycle in which the transport means (4 ) do not make a longitudinal movement, first one

The speed of rotation is slowed down (B ₅ F) and the speed of rotation is subsequently accelerated (C, G) to the value relevant for the subsequent section (25, 27, 40, 42).

18. The method according to any one of claims 12-17, characterized in that the press (1-3, 31) is operated with a number of strokes of more than 200 strokes / min, preferably in the range of or more than 300 strokes / min.