EP2104578B1 - Die cushion device comprising a modular hybrid drive unit - Google Patents

Abstract

The invention relates to a die cushion device (50) for a forming press (51) for generating a blank retaining force (F53) between a bottom die (5) and a top die (3). Said die cushion device (50) comprises at least one hybrid drive unit (52) which acts upon at least one blank holder (4) of the bottom die (5) and is formed by at least one first drive unit and at least one second drive unit. The first drive unit and the second drive unit form a die cushion module (9) that encompasses a part, by means of which the blank holder (4) can be moved upward and downward by at least one of the drive units. A downward pressure that can be transmitted from the top die (3) to said part and causes a descending movement can be blocked or decelerated only by the first drive unit in order to prevent the second drive unit from being overloaded, the part being disconnectable from the second drive unit during the descending movement.

Description

The invention relates to a die cushion device which, in combination of fluid and electric drive, is designed as a module and which can be adapted as a drawing device in a press by the use of one or more modules to different part geometries.

State of the art

In presses are used to pull blanks hydraulic pulling devices, which are arranged in the press table and apply pressure in the press table via movable pressure plates and a defined force on the blank holder, which presses the edge of the drawn part against the upper tool. Complicated and large-scale drawn parts require a different force setting on the drawing part edge. In DE 3807683 A1 a pulling device is known which consists of several independently acting pressure cylinders and each pressure cylinder is associated with a pressure cheek, which applies an individually adjustable force on the blank holder and Ziehteilrand. The disadvantage here is the high control and control effort that must be operated in particular for the synchronization during pre-acceleration and elevating and for the safety-oriented locking of the pulling device. The use of complex hydraulic controls also requires the operator to have specially trained personnel for the maintenance and service of the die cushion device.

Recently, die cushion devices have been known which use only electric drives to control the cushion movements and to apply the counterforce force. Out DE 10 2005 028 903 A1 Cushion modules are known, which consist of an electric servomotor and a power transmission mechanism for converting the rotational movement into a lifting and lowering movement and transmitted via cushion blocks the desired force on the drawing part edge. A disadvantage of this design is the required large space for housing the electric drive, especially when high nominal forces are required and several modules must be arranged within a press table. Furthermore, it is difficult for mechanically driven presses to maintain a sufficiently high counter-holding force in the lower reverse region of the ram with the electric drive when the movement speed approaches zero.

A compromise of high power density, a significant advantage of the hydraulic drive systems and a good maintainability and good controllability, a special feature of the electric drives are hybrid systems, as in WO 2006/000188 A1 has become known. In this case, hydraulically acting displacement cylinder take over the application of the counter-holding force during the drawing process and at least one electric cylinder, the control and regulation of the cushion movements outside the power flow with the press drive. However, this hybrid-type die-cushion device only permits a limited design in the form of a module to a limited extent, since the two drive forms are not concentrated in one axis. Furthermore, the previously known electrically driven die cushion devices with respect to the hydraulic die cushion do not have sufficient overload protection. For example, the electric drive is not able to correct a larger existing speed difference in the time of impact of the press ram on the die cushion device so that high accelerations on the inertia of the power transmission mechanism act and destroy it by high resulting forces.

Pneumatic drawing cushions have also been used for some time in forming technology. In single-acting presses, pneumatic cylinders are located in the area of the press table. These pneumatic cylinders usually act on a pressure cheek and pressure pins on a blank holder. The pressure chambers of the pneumatic cylinder are usually connected to a large-volume accumulator, which reduces the pressure increase to the lower reversal point. The type of pneumatic cushions are closed systems and have no power control but no further control options. They are displaced by the press ram and immediately follow it in the downward movement, the force in the downward movement being equal to the force in the upward movement. The per se very simple pneumatic die cushion is increasingly complicated at high drawing and Auswerfergeschwindigkeiten and required for large pulling forces either very large piston diameter or a very large length, due to the series connection of several pistons. The proportion of the moving masses generates high inertial forces with increasing pulling speeds, which add up to the cushion force uncontrollably at the moment of the drawing start.

To counteract the disadvantages of the pneumatic die cushion, nitrogen cylinders are sometimes used in forming technology. In "The use of the Nitro-Dyne gas spring system instead of steel springs, strips, sheets, tubes 11-1974" describes the applications of such nitrogen cylinders. The nitrogen cylinders act similar to a mechanical spring, but offer some advantages. For example, nitrogen springs have full power right from the start. In addition, the increase in force over the travel of a nitrogen spring is much lower than conventional springs. Another advantage of nitrogen springs is the very high power density. In the in the Forming technology used nitrogen cylinders, there are different types. In the so-called single-chamber system, piston and piston rod form one unit. The seal happens here on the piston. There is a scraper on the piston rod. The upper chamber is thus vented to the atmosphere. The single-chamber system is characterized by a short stroke and a progressive force curve. When such a system is connected to an external storage volume, it is referred to as a tank system. In a tank system, it is possible to adapt the force increase of the spring over the spring travel to the requirements.

Task and advantage of the invention

The invention is based on the object, starting from the prior art, to improve a die cushion device with hybrid drive such that for one of the drives a safe and easy-built overload protection is given and further that the space required for a single die cushion module is reduced ,

This object is achieved on the basis of the features of the preamble of claim 1 by the characterizing features of claim 1. The features mentioned in the dependent claims advantageous embodiments and modifications of the invention are possible.

In the die cushion device according to the invention, the first drive and the second drive form a die cushion module, wherein the die cushion module comprises a component, by means of which the sinker holder of at least one of the drives with a lifting movement is movable upwards or with a lowering movement downwardly, while a a pulling operation of the upper tool on the component transferable, downwardly directed, a Niederfahrbewegung causing compressive force to avoid overstressing the second drive only by the first drive blockable or braked and wherein the component is decoupled from the second drive in the downward movement down. As a result, a secure overload protection of the second drive against forces and movements is achieved, which emanate from the upper tool. For the second drive can thus be dispensed with expensive protective measures or an expensive design to loads by the upper tool. The core of the invention is to integrate the second drive in the hybrid drive, that this can meet without any impairment of its tasks, in particular a sensitive control and regulation of a lifting movement of the board holder, but of forces or movements with which the upper tool on the board holder also acts on the hybrid drive or the die cushion module is decoupled. Such a decoupling is achieved mechanically by a freewheel acting in a direction of movement between the second drive and the component which is directly or indirectly tucked with the sinker holder. The freewheel protects the second drive against overloads, as they can not be transferred to the second drive by utilizing the freewheeling function.

The invention provides, in particular, to use the hybrid principle to arrange the electric drive with its power transmission mechanism in an axis to a hydraulic cylinder or a nitrogen cylinder or a mechanically sprung cylinder or a similar drive and pass the piston rod of the cylinder through the power transmission mechanism of the electric drive and the Piston rod directly or indirectly, in particular to bring about the pressure cheek with the board holder in operative connection. As a result, a particularly compact design is achieved, since a component of the first drive, in particular a piston rod of both drives used as an operative connection to the downstream components and does not need to be performed twice as is the case with known hybrid drives.

The great advantage of this arrangement is thus that the electric drive, which is also referred to as a second drive, no immediate or no all forces and movements transmitting connection to the board holder or the pressure cheek has and at the moment of impact of the press ram on the board holder and disengaged in the event of overload. The electric drive preferably acts on a collar of the piston rod of the hydraulic cylinder via a ball or roller screw drive.

In the downward movement of the piston rod is pre-accelerated until the press ram has placed on the board holder or blank holder. At this moment, the hydraulic system, consisting of cylinder, arranged on the outlet side proportional valve and pressure sensor, and arranged on the inlet side check valve and low-pressure accumulator, active and counteracts with a defined force the plunger. The force is applied by a cylinder-controlled pressure acting on the piston surface. The pressure is generated passively by oil displacement against a proportional valve. The electric drive follows the piston rod and does not necessarily have to be in operative connection with it.
The overload protection is common as with hydraulic drawing cushion, given by a further discharge side arranged pressure relief valve.

In the lower reversal point of the plunger or the die cushion device, the contact between the electric drive and the piston rod is restored. After completion of the oil displacement, the pressure of the low pressure accumulator acts on the check valve in the cylinder and pushes the piston rod with its collar against the electric drive. In this state, the upward movement takes place, which in turn by the electric drive to be led. It makes sense to set the value of the accumulator pressure in such a way that the sum of mass and flow forces as well as the forces required to lift the drawn part out of the lower tool can be applied. A position measuring system attached to the cylinder base directly detects the movement of the piston rod and supplies the value of the control device of the electric drive.

The dimensioning of the electric drive also depends on the value of the resulting force, which generally corresponds to approximately 10% to 20% of the nominal force of the cylinder. This is a further advantage in order to reduce the space compared to purely electrically driven die cushion devices. The lower required nominal force of the electric drive allows a more favorable dimensioning of the power transmission elements, leads to lower mass moments of inertia, to a better dynamics of the drive and at the same time reduces heat generation.
The strict division of tasks of hydraulic and electrical system, the known advantages of a hybrid drive arise: the generation of pulling force required for pulling done by the hydraulic system with its high power density and its compact design and not executed in contact with the press ram movements of the die cushion device by run the simpler electric drive. It accounts z. As the additionally required safety valves in the hydraulic system, as dangerous movements can be safely prevented by the electric drive with simpler means.

The invention also provides for the first drive to use a nitrogen cylinder instead of a hydraulic cylinder or a mechanical cylinder. Thus, as a hybrid drive or as a die cushion module, a nitrogen cushion module is produced, consisting of an electric drive and a nitrogen cylinder, which acts like a spring during the forming process. In a In the preferred embodiment, the amount of nitrogen in the cylinder during the operation of the nitrogen pad module remains constant, since the cylinder can be decoupled from the nitrogen supply during operation. Thus, the nitrogen supply system, consisting essentially of a high-pressure accumulator, a low pressure accumulator and a pressure booster, serves for presetting a spring force by filling or discharging nitrogen outside of the operation. Although the amount of nitrogen in the cylinder is not changed during the forming process, the overall system of the nitrogen cushion module can still operate regulated. The control is effected by a superimposition of the nitrogen spring force and a force resulting from the electric drive. During the deformation, for example, the electric drive can generate a force which counteracts the nitrogen spring force. The effective force is thus reduced during the drawing process by the electric drive. In the upward movement, in turn, a braking effect can be achieved by the electric drive. By the regenerative operation of the electric motor, an energy recovery in the upward gear can be realized. By means of these control technical possibilities, full functionality, such as pre-acceleration, hold-down, release stroke and cushioning, can be ensured in the die-cushion device according to the invention.

Another advantage of the inventive design of the die cushion device as a nitrogen cushion module is the ability to operate the die cushion uncoupled from the nitrogen supply. This allows the construction of modular multi-point drawing devices, which can be arranged both in the press table, as well as directly in the sliding table.

Further details and advantages of the invention will become apparent from the embodiment illustrated in the drawings.

Further details and advantages of the invention will become apparent from the embodiment illustrated in the drawings.

Fig. 1:

Presse mit Ziehkissenvorrichtung;

Fig. 2:

Prinzipieller Aufbau eines Ziehkissenmoduls;

Fig. 3:

Bewegungszyklus der Ziehkisseneinrichtung;

Fig. 4:

Prinzipieller Aufbau eines weiteren Ziehkissenmoduls;

Fig. 5, 6:

Detaildarstellungen des in der Figur 3 gezeigten Ziehkissenmoduls in unterschiedliche Stellungen der Kolbenstange und der Spindel.

Show it:

Fig. 1:

Press with die cushion device;

Fig. 2:

Basic structure of a die cushion module;

3:

Movement cycle of the die cushion device;

4:

Basic structure of another die cushion module;

5, 6:

Detailed representations of in the FIG. 3 shown die cushion module in different positions of the piston rod and the spindle.

Description of the embodiments

In FIG. 1 is the schematic structure of a forming press 51 for drawing large-area parts 10, which are designed for example as boards 53 made of plastic or sheet metal. The press has a mechanical drive 1, which moves the plunger 2 with upper tool 3 up and down. In the press table 8 a die cushion device 50 is arranged with hybrid drives 52, which consists of a press table 8 vertically displaceable pressure cheek 7 and several die cushion modules 9 and hybrid drives 52. On the pressure cheek 7 are pressure pin 6, which hold the board holder 4 with the drawn part 10 and from below with a board holding force F53 on the Pull part 10 act. After placing the plunger 2, the upper tool 3 comes via the drawn part 10 with the board holder 4 in conjunction and displaces this against the pressure pin 6, the pressure cheek 7 and the die cushion modules 9, which support the pressure cheek 7. Each die cushion module 9 counteracts with an adjustable force of the plunger movement and thus braces the drawing part edge between the board holder 4 and upper tool 3 in a defined manner. As a result, the inflow of material of the drawn part 10 can be selectively controlled or regulated in the form formed by the upper tool 3 and the lower tool 5.

In FIG. 2 the basic structure of a die cushion module 9 is shown. The hydraulic system consists of a plunger cylinder 11 designed as a hydraulic cylinder with a piston rod 12 with a splined shaft profile 13, a displacement measuring system 32 arranged on the bottom side, and the proportional valve 21, pressure limiting valve 22 and the pressure transmitter 23 arranged in the discharge line 24 the check valves 27 and 29 located in the supply line 30, the piston accumulator 28 and a pump 26 with a valve for pressure limiting 31. The hydraulic cylinder 12 forms a first drive.
An electric drive 14, which forms a second drive, includes a rotor 15 configured as a hollow shaft and optionally a spring-pressure safety brake 16. A transmission for converting the rotational movement of the rotor 15 into a lifting and lowering movement of the piston rod 12 is a ball screw consisting of hollow Spindle 18 which is positively connected to the piston rod 12 and the spindle nut 17 which is fixedly connected to the rotor 15. About the collar 19 of the piston rod 12, the spindle 18 is in its downward movement with its collar 55 positively connected to the piston rod 12 in connection. An anti-rotation device 20 connected to the housing of the hollow shaft or torque motor 14 fixes the piston rod 13 via the splined shaft profile and thus allows the translation of a rotational movement in a translational movement.

The pump 26 fills the piston accumulator 28 via a check valve 27 with hydraulic oil to a pressure value which corresponds to the sum of maximum possible mass and flow forces and the required force for lifting the drawn part 10 from the contour of the lower tool 5. Excess pressure oil is z. B. returned to the tank via a pressure relief valve 31. At higher pressures, it will be used for energy reasons at this point a valve for accumulator charge control.
A check valve 29 connects the piston accumulator 28 with the supply line 30 of the cylinder 11 and prevents backflow from the cylinder.
The thereby acting on the piston 12 pressure raises the piston rod 13 and presses it against its collar 19 against the spindle 18 of the ball screw. By not shown, but well-known control device, the electric drive is driven such that the piston rod can be moved to the desired position. An arranged on the cylinder bottom displacement measuring system 32 detects the movement of the piston rod directly and supplies the actual value to the controller.
During an upward movement, the hydraulic drive supplies the required energy. However, the position is generally determined by the electric drive. The proportional valve 21 remains closed. For the downward movement, however, the electric drive provides the kinetic energy and positions the piston rod as long as the plunger has not come into contact with the board holder. In this case, the proportional valve 21 must release the outflow from the cylinder. To prevent unnecessary pressure oil from flowing out of the accumulator, the pressure in the cylinder is regulated to a value above the accumulator pressure. The pressure transducer 23 provides the required actual pressure value.

Once the plunger has come into contact with the board holder, the control of the predetermined pressure value for the drawing process takes place. The placement of the plunger is detected by comparing the positions of plunger and piston rods of the die cushion modules. It is also possible at higher differential speeds to detect the placement of the plunger by a pressure increase in the cylinder.

In the event of failure of the pressure control loop or the proportional valve 21 prevents a discharge-side arranged pressure relief valve 22 overloading the cylinder and the mechanical power transmission elements.

Another failure can z. B. arise due to the failure of the power supply for the electric drive, which was considered to be critical especially shortly before impact of the plunger. Since due to the follow-up path and the stored energies of the ram does not come to a standstill in time, it will put on the board holder at high speed. Since the power transmission elements of the die cushion apparatus can not be designed for the nominal force of the plunger for reasons of complexity and space, damage is foreseeable. For this reason, there is no positive connection between the electric drive 14 and the piston rod 13 in a direction opposite to the plunger movement direction, so that the piston rod can be moved with hydraulically limited force from the plunger while the electric drive blocks.

A safety-oriented locking of movements of the die cushion device in the upward direction is possible by means of the spring-pressure safety brake 16. The braking torque is applied by spring force to the rotor 15 of the engine. In addition, rapid lowering movements can be prevented by using safety-related valves in the outflow line 24 of the cylinder. Thus, optionally, the proportional valve 21 can be designed as a fail-safe valve.

FIG. 3 describes a complete cycle of motion of the hybrid-type die cushion device.
Outside the drawing area, the electric drive assumes the positioning of the die cushion device. This preferably takes place synchronously with the movement of the plunger, in that corresponding to the torque motor or the hollow shaft motor corresponding position desired values are predefined as a function of the crank angle of the press drive. Within the drawing range of the electric drive of the piston rod runs, which is driven in this section by the plunger. This can be done by limiting the motor current or the torque to stay in contact with the piston rod with little force or by using another displacement measuring system which detects the position of the spindle. By comparing both position values, the spindle can be tracked without contact at a small distance.

In the lower reversal point of the press again the electric drive takes over the leadership of the pillow movements and raises z. B. the pressure cheek of the die cushion device delays to the plunger movement by a certain amount to allow transfer devices to remove the drawn part and then brings the die cushion device back to the starting position.

The padding operation is a special case, wherein the first portion of the run-up movement of the die cushion device takes place in contact with the plunger until the beginning of the braking phase. Thus, the piston rods can create with the force of the hydraulic system against the board holder and plunger, the electric drive is performed with respect to the displacement measuring system of the plunger with a small distance above the collar 19 until the braking phase begins.

Due to the good controllability of electric drives a precise synchronization of several die cushion modules is possible, so that different arrangement variants and combinations are possible.

In FIG. 4 the basic structure of a further die cushion module 101 according to the invention can be seen. As already described, the die cushion module 101 essentially consists of two parts, namely the electric drive 102, which is also generally referred to as the second drive, and a spring 103, which is generally referred to as the first drive. The spring 103 is preferably designed as a nitrogen cylinder, wherein the spring force of the spring 103 counteracts the pressing force. The spring force of the nitrogen cylinder 103 can be regulated by filling or discharging nitrogen with a nitrogen supply unit 104. This nitrogen supply unit 104 consists of a low-pressure accumulator 105, in which excess nitrogen can be discharged, a high-pressure accumulator 106, from which the nitrogen cylinder 3 can be filled with additional nitrogen, a pressure interrupter 107 connected therebetween and corresponding valve technology. The nitrogen supply unit 104 can be arranged both directly on the nitrogen cylinder 103, as well as outside the press as a separate supply station. In the in FIG. 4 The transmission for converting the rotational movement into a lifting and lowering movement of the piston rod 109 is a ball screw 110, consisting of a hollow spindle 18 which is positively connected to the piston rod 109 and a spindle nut 17, which is fixedly connected to a rotor 15 of the hollow shaft motor 108. About a collar 19 of the piston rod 109 is the spindle 18 with its collar 55 during its downward movement form-fitting manner with the piston rod 109 in connection. An anti-rotation 111 fixes the piston rod 109 via a spline shaft 13 and thus enables the translation of a rotational movement in one Translational motion. The driving force of this translational movement is superimposed with the spring force of the nitrogen cylinder 103. Although the nitrogen cylinder 103 is a closed system during operation, this superposition can solve all of the die-art control tasks known in the art.

The Figures 5 and 6 show detailed representations of in the FIG. 3 shown die cushion module 9, which is essentially formed by a hybrid drive 52, in different positions of the piston rod 12 and the hollow spindle 18. The hybrid drive is used in particular the generation and control of a board holding force, with which a drawn part or a board of at least one board holder during of the drawing operation is pressed against the upper tool. Compared to the one in the FIG. 3 shown position of the hybrid drive is the piston rod 12 in the FIG. 5 with a lowering L dropped in an arrow direction y '. Such a lowering movement L of the piston rod 12, which is also generally referred to as component 12, results, for example, in the course of a drawing operation by a downward movement of the upper tool, which also acts indirectly on the piston rod 12. The lowering movement L of the piston rod 12 along its axis a is independent of a position of the hollow spindle 18 of the electric drive 14. A relative movement between the hollow spindle 18 and the spline 13 of the piston rod 12 is unimpeded, since the hollow spindle 18 on the spline 13th the piston rod 12 in the direction of the axis a can slide up and down unchecked. The hollow spindle 18 is driven by the spindle nut 17 on the spline shaft 13 of the piston rod 12 in the y or y 'direction freely movable, but not with respect to the piston rod 12 about the longitudinal axis a rotatable. In the in the FIG. 5 shown position in which the piston rod 12 has dropped relative to the hollow spindle 18 of the second drive 14, the formed on the piston rod 12 collar 19 is particularly good recognizable. With this in the y'-direction considered annular collar 19, the piston rod 12, as in the Figures 3 and 6 The electric or second drive 14 forms with its spindle 18 a height-adjustable stop 54 for the first drive or for the piston rod 12 of the cylinder 11. In the in the FIG. 6 illustrated position of the hybrid drive 52, the electric drive 14 has moved its spindle 18 in the direction of arrow y 'along the axis a down, so that the spindle 18 rests with its collar 55 on the collar 19 of the piston rod 12. As a result, the piston rod 12 is secured in the position shown against a further stroke H in the y direction. Another stroke H of the piston rod 12 is controlled or controlled by the electric drive 14, which moves in a predetermined manner by the control with its spindle 18 upwards. Of course, it is the electric drive 14 also possible with its spindle 18, the piston rod 12 of the hydraulic drive formed by the cylinder 11, for example, to correct a struck position in the direction of arrow y 'to press down. Here, the force of the cylinder 11, with which this pushes the piston rod 12 upwards in the direction of arrow y, preferably reduced. Regardless of the position of the spindle 18, the piston rod 12 can sink at any time in the y 'direction, without burdening the electric drive 14 when sinking. Thus, the electric drive 14, which is also referred to as the second drive 14, protected without any control or technical control effort before the so far for die cushion devices so dangerous overloads. The piston rod 12, which is a component 56 of the cylinder 11 which forms the first drive, is also used for the direct or indirect actuation of the board holder by the electric drive 14, which forms the second drive.

The invention is not limited to the described and illustrated embodiment. It also includes all expert embodiments within the scope of the inventive idea.

For example, a common nitrogen pressure chamber can be used for several cushion modules, wherein a plurality of die cushion modules are connected to the common pressure chamber. This common nitrogen pressure chamber can also be a pressure-tight cavity in the sliding table, this pressure chamber being provided in particular for a supply of several die cushion modules. Alternatively, the invention also provides for arranging the nitrogen supply unit outside the press as set-up station. The invention also provides to control the amount of nitrogen in the nitrogen cylinder.

In a further advantageous embodiment of the die cushion device 101 according to the invention, the amount of nitrogen in the nitrogen cylinder 103 can not only be changed as a set-up process, but also be regulated during operation.

For example, the in FIG. 1 illustrated pressure cheek 7 split executed. In this case, the die cushion modules 9 of the invention do not act on a common pressure cheek 7, but on individual pressure cheek segments. These segments in turn act on the board holder 4 via one or more pressure bolts 6.

As a further variant can be completely dispensed with the pressure cheek 7. The piston rods of the die cushion modules 9 according to the invention then act either directly or via pressure bolts 6 on the board holder 4. The board holder 4 can be designed both as a conventional, and as a segment elastic circuit board holder.

In a further advantageous embodiment of the invention, the die cushion modules 9 are integrated in the mobile sliding table. That is, the die cushion modules 9 and the associated movement or force transmission means are accommodated in the sliding table body and extended or retracted during a tool change with the sliding table.

The invention further provides for the board holder (4) to be designed as a segment-elastic board holder. It is also envisaged to integrate the die cushion modules in one or more sliding tables. Furthermore, the invention provides to realize the electric drive functions of several die cushion modules via suitable motion transmission means of a common drive. It is also envisaged to realize the hydraulic drive functions of a plurality of die cushion modules via suitable motion transmission means of a common drive. Furthermore, the invention provides to control or regulate the electric drive functions of several die cushion modules individually and / or jointly. According to the invention, it is also provided to control or regulate the hydraulic drive functions of several die cushion modules individually and / or jointly. To increase safety, it is provided to allow by means of a spring-pressure safety brake locking the die cushion device in the upward direction. Finally, it is provided to prevent by means of safety-oriented valves in the discharge line of the cylinder rapid lowering movements of the die cushion device.

LIST OF REFERENCE NUMBERS

1

mechanical drive

2

tappet

3

upper tool

4

Board holder or blank holder

5

lower tool

6

pushpin

7

pressure cheek

8th

press table

9

Cushion modules

10

drawn part

11

Cylinder, plunger cylinder (first drive)

12

piston

13

Spline

14th

electric drive (second drive)

15

runner

16

Spring applied safety brake

17

spindle nut

18

spindle

19

Federation

20

twist

21

proportional valve

22

Pressure relief valve

23

Pressure Transmitter

24

drain line

25

tank

26

pump

27

check valve

28

piston accumulators

29

check valve

30

supply

31

pressure relief

32

displacement measuring system

50

A die cushion device

51

forming press

52

hybrid drive

53

Board or sheet metal

54

height adjustable stop

55

ring-shaped collar on 18

56

Part of 11

101

Cushion module

102

electric drive (second drive)

103

Spring, nitrogen cylinder (first drive)

104

Nitrogen-supply unit

105

Low-pressure accumulator

106

High-pressure accumulator

107

Pressure intensifier

108

Hollow shaft motor

109

piston rod

110

Ball Screw

111

twist

F53

Blank-holding force

A

Axis or longitudinal axis of 12

H

Lifting movement of 12

L

Lowering movement of 12

a

Axis or longitudinal axis of 12

Claims (15)

1. Die cushion device (50) for a forming press (51) for generating a plate retaining force (F53) between a bottom die (5) and a top die (3), wherein the die cushion device (50) comprises at least one hybrid drive (52) which hybrid drive (52) acts upon at least one plate holder (4) of the bottom die (5), and wherein the hybrid drive (52) is formed by at least one first drive (11, 103) and at least one second drive (14, 102), characterised in that the first drive (11, 103) and the second drive (14, 102) form a die cushion module (9), wherein the die cushion module (9) comprises a component (12, 109), by means of which the plate holder (4) can be moved upwards by at least one of the drive units (11, 14) by a lifting movement (H) or can be moved downwards by a lowering movement (L), wherein a pressure force that can be transmitted by the top die (3) during a drawing process onto said component (12, 109) and causing a descending movement can be blocked or decelerated only by the first drive unit In order to prevent the second drive (14, 102) unit from being overloaded and wherein during the descending movement the component (12, 109) can be uncoupled from the second drive (14, 102).
2. Die cushion device according to claim 1, characterised in that the lifting movement (H) in the direction of the upper die (3) that can be generated by the first drive (11, 103) can be controlled or regulated by the second drive (14, 102), wherein in particular the second drive (14, 102) forms a height-adjustable stop (54) relative to the component (12, 109), and wherein in particular the lifting movement of the component (12, 109) can be finely adjusted by the second drive (14, 102).
3. Die cushion device according to one of claims 1 or 2, characterised in that the component (12, 109) during the lifting movement (H) can only be driven by the first drive (11, 103), whereby in particular the component (12, 109) is a component (56) of the first drive (11, 103) and is designed in particular as a piston rod (12, 109).
4. Die cushion device according to one of the preceding claims, characterised in that the drives (11, 14; 103, 102) forming the hybrid drive (52) have different properties in particular with respect to the type of drive and/or strength of the drive.
5. Die cushion device according to one of the preceding claims, characterised in that the component (12, 109) can be lowered by the second drive (14, 102) in particular against a reduced counter-force of the first drive (11, 103).
6. Die cushion device according to one of the preceding claims, characterised in that the pressure loading and the movement of the plate holder (4) is generated by one or more die cushion modules (9), wherein the die cushion modules (9) consist of at least two drives (11, 14; 103, 102) the directions of force and movement of which lie on an axis (a), wherein In particular the die cushion modules (9) consist of an electric drive (14) and a hydraulic drive (11) or wherein the die cushion modules (101) consist of an electric drive (102) and a spring (103), wherein the spring (103) in particular is a nitrogen cylinder and wherein in particular the nitrogen cylinder (103) has a closed pressure chamber, wherein the amount of nitrogen can be changed, and wherein in particular the nitrogen cylinder (103) can be connected to a low pressure store (5) and/or a high pressure store (106).
7. Die cushion device according to claim 6, characterised in that the die cushion modules (9, 101) consist of an electric drive (102) and a spring (103), wherein the spring (103) in particular is a mechanical spring.
8. Die cushion device according to one of the preceding claims, characterised in that during the shaping process between the second drive (14, 102), which is designed in particular as an electric drive (14, 102), and the piston rod (12, 109) there Is no form-closed connection in a direction of movement opposite the ram (2), whereby preferably the electric drive (14, 102) acts on a collar (19) of the piston rod (12) of the cylinder (11, 103) in particular a hydraulic cylinder (11) or a nitrogen cylinder (103) or a mechanically sprung cylinder.
9. Die cushion device according to one of the preceding claims, characterised in that the second drive (14, 102), which is designed in particular as an electric drive (14, 102), acts by means of a ball or roller thread drive (17, 18, 110) on the collar (19) of the piston rod (12), or in that the second drive (14, 102), which is designed in particular as an electric drive (14, 102), is in particular a hollow shaft motor or In particular a torque motor.
10. Die cushion device according to one of claims 3 - 9, characterised in that a wedge shaft profile (13) is attached onto the piston rod (12, 109), which profile by means of a rotary locking mechanism (20, 111) prevents the rotation of the piston rod (12, 108) about the longitudinal axis (a) of the piston rod (12, 109).
11. Die cushion device according to one of claims 6 - 9, characterised in that the die cushion modules (9) act via a common pressure cheek (7) and via pressure bolts (6) on the plate holder (4), or in that preferably the die cushion modules (9) act by at least two pressure cheek segments and pressure bolts (6) on the plate holder (4), or In that preferably the die cushion modules (9) act via pressure bolts (6) on the plate holder (4), or In that preferably the die cushion modules (9) act directly on the plate holder (4), wherein in particular the plate holder (4) is designed as a segment-elastic plate holder.
12. Die cushion device according to one of the preceding claims, characterised in that the die cushion modules (9) are integrated into one or more sliding tables, wherein in particular the electrical drive functions of several die cushion modules (9) are achieved by suitable movement transmission means by a common drive, and wherein in particular the hydraulic drive functions of several die cushion modules (9) are achieved by suitable movement transmission means by a common drive.
13. Die cushion device according to one of the preceding claims, characterised in that the electrical drive functions of several die cushion modules (9) are controlled or regulated individually and/or jointly and/or in that preferably the hydraulic drive functions of several die cushion modules (9) are controlled or regulated individually and/or jointly.
14. Die cushion device according to one of the preceding claims, characterised in that the die cushion modules (9) by means of a spring-pressure safety brake (16) allow the locking of the die cushion device in upwards direction.
15. Die cushion device according to one of the preceding claims, characterised in that by means of the safety-aligned valves in the outflow line (24) of the cylinder (11, 103) rapid sinking movements of the die cushion device are prevented.

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