WO2012032041A2

WO2012032041A2 - Drive device with linear motor for a press

Info

Publication number: WO2012032041A2
Application number: PCT/EP2011/065385
Authority: WO
Inventors: Dieter Reisch; Michael Micklisch
Original assignee: Schuler Pressen Gmbh & Co. Kg
Priority date: 2010-09-06
Filing date: 2011-09-06
Publication date: 2012-03-15
Also published as: JP2013540592A; DE102010037330B4; CN103189193B; DE102010037330A1; JP5706965B2; CN103189193A; WO2012032041A3

Abstract

The invention relates to a drive device (19) for a secondary drive of a press and in particular of a drawing press (10). The drive device (19) serves in particular as a bed cushion drive. It has an electric linear motor (27), the rotor (46) of which is rigidly connected to a transmission piston (35) of a fluidic transmission unit (28). The fluidic transmission unit has a first pressure chamber (38a), which is connected via a first fluid line (39) to a first working chamber (41) of a working cylinder (29). The fact that the piston area (F1) of the transmission piston (35) that is adjacent to the first pressure chamber (38a) is smaller than the piston area (F3) of the working piston that is adjacent to the first working chamber (41) means that an increase in the force of the linear motor (27) by a factor corresponding to the ratio of the areas is achieved. This allows the forces necessary at the working cylinder (29) to be achieved with the aid of the linear motor (27).

Description

Drive device with linear motor for a press

The invention relates to a drive device for a press and in particular for the table cushion of a drawing press. The press has a press on a main ^¬ drive in the working direction driven plunger which is movably supported on a press frame. The ram carries an upper tool. At a distance from the plunger, the lower tool is angeord ^¬ net on a press table of the press frame. On the side facing away from the upper tool Pres ^¬ sentisches is a table cushion with a floating ^¬ plate, which can be moved and positioned over a working cylinder assembly in the direction of the press. The working cylinders of the working cylinder arrangement belong to a drive device by means of which the floating plate is moved.

A drive device for a press is known for example from DE 2006058630 AI. There, a dop ^¬ pelt acting working cylinder is provided with two working chambers. Depending on the direction of movement, one of the two working chambers is filled with hydraulic medium via a motor-pump unit. A reversal of direction of the E lektromotors also leads to reversal of the BEWE ^¬ supply of the hydraulic working cylinder. Acts by the upper tool or the plunger of the press a force on the floating plate, the electric motor can also be operated in generator mode, so that energy recovery is possible. Rotary electric motors are not opti ^¬ times in terms of control accuracy and their efficiency. The rotational movement of the electric motor must be converted into a linear movement of the working piston of the working cylinder. This conversion of Rotationsbewe ^¬ tion in a linear movement of the efficiency of the drive is adversely affected.

A purely electric drive device for the table cushion is described in DE 10 2005 026818 AI. There, the floating plate is driven by linear electric motors di ^¬ rectly. The linear motors are therefore arranged in the direction of the press below the table top. This arrangement requires a large space in the direction of the press below the press table. It may be necessary to design the press foundation recessed in the area of the linear cylinder in order to ensure access to the linear cylinders later, for example for maintenance or repair work. Secondly, a large number of linear drives is necessary in order to achieve the high forces that need to be supported by the lower tool during the drawing process ^¬. The electrical network is also heavily loaded.

Starting from this known state of the art, it can be regarded as an object of the present invention to provide an improved drive device. In particular, the space of the press in the working direction should be very small and the efficiency of the drive device can be increased.

This object is achieved by a drive device having the features of patent claim 1. According to the invention, the drive device has an electric linear motor, which is controlled by a control unit. The rotor of the linear motor moves along a drive axis. In particular, a translation tube of a translation unit is rigidly connected to this runner. The translation unit is designed as a fluidic and ^¬ preferably hydraulic piston-cylinder unit and is used for power increase in engine power provided by the linear motor. The translation unit and the working cylinder form a closed hydraulic circuit. The booster piston sits fluid-tight in a housing interior. There it defines at least one pressure chamber, which is connected via a fluid line to a working chamber of a working cylinder of the press. The working cylinder is preferably used for movement and positioning of the floating plate of a table cushion.

In this arrangement, the linear movement of the working piston of the working cylinder is generated by a li ^¬ linear movement of the rotor of the linear motor. A conversion of a rotary movement into a linear movement is eliminated. As a result, the efficiency of the drive device can be increased. The translation unit between working cylinder and linear motor ensures that a sufficiently large force is exerted on the working piston of the working cylinder. This is preferably characterized ^¬ it suffices that the effective piston area of the working piston is significantly smaller than the effective piston area of the piston Ü Berset wetting. Although this leads to an extension of the linear travel of the rotor of the linear motor ge ^¬ compared with the travel of the working piston. Due to the interposition of the fluidic translation unit, however, the linear motor does not necessarily have to be arranged in the working direction of the press below the press table. Preferably, the linear motor sits on the press frame or at the press table. Its longitudinal axis is in particular aligned transversely or at right angles to the working direction of the press. Even in the fully extended condition, the total length of the linear motor and associated translation unit is not greater than the width of the pressing ^¬ frame or of the press table so that the linear motor and the translation unit does not have the extend the press frame and the press table.

Thus, a drive device with high efficiency at the same time optimal space utilization is achieved at the press.

It is advantageous if the fluid line between the linear motor and the working cylinder is designed as a rigid tube. In this way, pressure-reducing elasticities between the pressure chamber of the translation unit and the working chamber of the working cylinder can be avoided.

Preferably, each working cylinder of the working cylinder arrangement of the press is assigned a separate linear motor via a separate translation unit. In this case, each cylinder can be operated separately by controlling the respective associated linear motor.

It is also of advantage when the rotor of the linear motor and connected to the rotor transla ^¬ wetting piston move along a common axis. The power of the rotor is optimally transmitted to the translation ^¬ piston.

The connection between the rotor and the transmission piston is preferably realized by a rigid connection ^¬ element. The connecting element is designed in such a way from ^¬ that both tensile and compressive forces aufneh- can. Thus, a power transmission from the transmission piston to the rotor is possible, for example, when the linear motor operates in generator mode. During motor operation, the linear motor can move or position the floating plate. In generator operation, the force exerted by the plunger on the lower tool on the floating plate force can lead to egg ^¬ ner linear movement of the transmission piston and the Läu ^¬ fers. The electrical energy generated in this case can be fed back into the electrical network or stored in an energy ^¬ memory. The energy storage can also provide energy for the press main drive.

Advantageous embodiments of the invention will become apparent from the dependent claims and the description. The description is limited to essential features of the invention. The drawing is in addition he ranzuziehen ^¬. Show it:

FIG. 1 shows a schematic side view of a press,

Figure 2 is a schematic partial view of the press of Figure 1 with an embodiment of a drive device with a linear motor and translation unit and

FIG. 3 shows a block diagram of the drive device from FIG. 2.

1 shows a schematic side view of a drawing press 10. The drawing press 10 has a press frame 11, on which a plunger 12 is movably mounted in a working direction A. About a press main drive 13, the plunger 12 can be moved linearly in the working direction A. The working direction A preferably runs in the vertical direction.

The plunger 12 carries an upper tool 14. At a distance from the upper tool 14, a lower tool 15 is arranged on a press table 16 of the press frame 11. On the opposite side in the working direction A to the lower tool 15, the drawing press 10 has a table cushion 17 with a floating plate 18. A drive device 19 is used for positioning and / or movement of the floating plate 18 in the working direction A of the drawing press 10. The drive device 19 can therefore also be referred to as a table cushion drive.

On the floating plate 18 a plurality of push rods 20 are arranged, which enforce the press table 16 and at its upper tool 14 facing the end of a sheet metal holding ^¬ ring 21 wear. The sheet metal holding ring 21 is used together with the upper tool 14 to pinch a sheet metal blank 22 and to apply a desired clamping force when pulling on the lower tool 15. This clamping force is set via the drive device 19 to the desired setpoint, which can assume different values during the drawing process.

The drive device 19 has a control unit 26, which drives a linear electric motor 27. The linear motor 27 is connected via a translation unit 28 with egg ^¬ nem working cylinder 29. The translation unit 28 serves to transmit the force of the linear motor 27 into a flow idkraft to transfer, which acts on a working piston 30 of the working cylinder 29. The working piston 30 is connected via a piston rod 31 with the floating plate 18, which sits on the protruding from the working cylinder 29 free end 32 of the piston rod 31. In the embodiment shown here, the drawing press 10 has only one working cylinder 29. In a modification to this, the drawing press 10 may comprise a working cylinder arrangement with a plurality of working cylinders 29. In this case, each working cylinder 19 is assigned a separate linear motor 27 and a separate translation unit 28. The linear motor ^¬ ren 27 can be controlled by a common control unit 26th Each working cylinder 29 is driven in the embodiment via only a linear motor 27. It would alternatively be possible to drive the cylinder over several linear motors.

The translation unit 28 is executed in the present case as a hydraulic translation unit 28. It has a transmission piston 35, which is arranged in a housing interior 36 of a cylinder housing 37. The transmission piston 35 is fluid-tight against the inner wall of the cylinder housing 37 and divides the housing interior ^¬ space 36 fluidly into a first pressure chamber 38 a and a second pressure chamber 38 b. The first pressure chamber 38a is connected via a first fluid line 39 to a first working chamber 41 of the working cylinder 29. The second Druckkam ^¬ mer 38b is connected via a second fluid line 40 with the two ^¬ th working chamber 42 of the working cylinder 29th The two working chambers 41, 42 are provided in the interior of the cylinder housing of the working cylinder 29 and fluidly separated from each other by the working piston 30. The second working chamber 42 is penetrated by the piston rod 31 and therefore forms an annular space around the piston rod 31 around. The translation unit 28 forms with the Arbeitszy ^¬ linder 29 a closed hydraulic system. A Pum ^¬ PE for pressure increase is not provided in this hydraulic system. Optionally, a can to at least the fluid lines 39, 40 and in particular the second fluid conduit 40, a memory 44 for buffering the hydraulic medium may be present in ^¬.

The two fluid lines 39, 40 can be designed by rigid tubes. Under the term rigid here is the design of the tube to understand that under the prevailing pressure no deformation and thus no volume changes in the pipe allows.

The transmission piston 35 is connected via a connecting element 45 with a rotor 46 of the linear motor 27. The connecting element 45 is preferably designed rod-shaped or tubular and can absorb both tensile forces and compressive forces. The translation piston 35 and the rotor 46 and preferably also the connecting element 45 are arranged along a common axis B, along which all three parts 35, 45, 46 can move. The stator 47 of the linear motor 27 is arranged immovable relative to the press frame 11.

The connecting element 45 passes through the second pressure ^¬ chamber 38 b of the translation unit 28. Both the translation piston 35 and the working piston 30 are thus designed as a differential piston. The first piston surface F1 facing the first pressure chamber 38a is therefore larger than the second piston surface F2 of the transmission piston facing the second pressure chamber 38b. The first working chamber 41 facing ^¬ third piston face F3 of the Arbeitskol ^¬ bens 30 is greater than that of the second working chamber 42 to- facing fourth piston surface F4. Here, the third Kol ^¬ benfläche F3 is greater than the first piston surface Fl of the transmission piston. Preferably, the third Kolbenflä ^¬ surface F3 by a factor of 5 to 15 and in particular to the Fak ^¬ gate 10 is greater than the first piston surface Fl. Accordingly, the fourth piston surface F4, greater than that of the second piston surface F2. Again, a factor in the range of 5 to 15 and preferably the factor 10 between the surface areas of the piston surfaces F2 and F4 can be selected.

The control unit 26 is used to control the linear ^¬ motor 27. The rotor can be moved along the axis B in both directions. To set the speed or acceleration, a frequency converter 50 may be provided which can set a corresponding magnetic traveling field independently of the mains frequency. To control the movement of the rotor 46, the control unit 26 is provided with input signals. For example, a position sensor 51, the position of the plunger 12 or the position of the plunger cha ^¬ rakterisierende size, such as the press angle determined and the control unit are transmitted 26th Via a further position sensor 52, the position of the rotor 46 or the position of another part of the drive device 19 that is coupled to the rotor 46 in a motion-coupled manner can be measured and transmitted to the control unit 26. In ^¬ example, the position of the floating plate 18 or the piston rod 31 of the Ar ^¬ beitszylinders 29 can be measured via the position sensor 52. In this way, the control unit 26 can control the linear motor 27 and regulate the position of the rotor 46 and the movement-coupled parts of the drive device 19. This control can be done depending on the plunger position. Additionally or alternatively, a force or pressure sensor 53 may also be present. be that measures a characterizing the force between sheet metal holding ring 21 and plunger 12 size and the Steuerein ^¬ unit 26 transmitted. For example, the hyd ^¬ raulische pressure of the first working chamber 41 or circuit in the first pressure chamber 38a or, preferably, in the first fluid 39 can be measured for this purpose. The control unit 26 is thereby able to perform both a position control of the floating plate or the sheet metal retaining ring 21, as well as a force ^¬ or pressure control. The type of control can be switched during the drawing process during the forming of the sheet blank 22. In this case, the line ^¬ armotor 27 can operate either in engine operation or in generator mode. During generator operation, the linear motor 27 generates electrical energy which can be stored back into the electrical network or into a suitable energy store 54. Before being stored in an energy store 54, the AC voltage generated in the generator mode will be rectified via a rectifier 55. Before feeding back into the grid, the frequency of the generated AC voltage must be adapted to the mains frequency. The frequency converter 50 can then be designed as a bidirectionally operating frequency converter.

The electrical energy generated in the generator operation is provided in a preferred embodiment of the drawing press 10 the main press drive via a common DC ^¬ intermediate ^circuit . Thus, the connected load of the press main drive of the drawing press can he ^¬ considerably reduced. In addition, the load on the electrical grid is reduced by voltage peaks. Furthermore, a flywheel storage often used in servo presses can be made smaller.

Preferably, by the control unit 26 and the frequency converter 50, the magnetic traveling field in stature 47 of the linear motor 27 generates. The rotor 46 is made of electrically conductive material and may have a winding. The voltage induced by the traveling field in the stature in the rotor 46 causes a Lorenz force that accelerates the rotor 46 along the axis B. The traveling field moves in the direction of the axis B faster than the rotor 46th

Alternatively, the rotor 46 may also include a permanent magnet. The poles of the permanent magnets are arranged in ^¬ direction of the axis B alternately one behind the other. In this embodiment, the rotor 46 moves synchronously with the traveling magnetic field in the stature 47th

The drive device 19 of the drawing press 10 operates as follows:

To extend the piston rod 31 of the working cylinder - which corresponds to a movement of the sheet metal holding ring 21 or the Schwe ^¬ beplatte 18 in the working direction A to the plunger 12 back - the rotor 46 along the axis B moves so be ^¬ moves that the first pressure chamber 38a of Translation unit 28 reduced and the second pressure chamber 38b magnified ^¬ ßert. In the process, the transmission piston 35 presses hydraulic medium into the first working chamber 41 of the working cylinder 29 via the first fluid line 39. Hydraulic fluid is drawn in from the second working chamber 42 into the second pressure chamber 38b. In order not to hinder the movement of the transmission piston, hydraulic medium can also be sucked from the reservoir 44 at any time. Due to the preference ^¬ larger by a factor of 10 third piston surface F3 compared to the first piston surface Fl, the force applied by the linear actuator 27 force is increased by this factor. In this way, the forces required by the working cylinder 29 can be achieved by a linear motor 27 with significantly lower maximum force. By the same factor is the travel of the transmission piston 35 is greater than the working travel of the working piston 30th

During the drawing process, in which the sheet metal blank 22 is pulled over the lower tool 15 and clamped between plate holder ring 21 and upper tool 14, the desired pressure is set in the first working chamber 41 of the working cylinder 29 by a corresponding energization of the Li ^¬ nearmotors 27. In this case, the piston rod 31 is retracted continuously, whereby the volume in the first working chamber 41 is reduced. The hydraulic medium located in the first working chamber 41 is pushed back into the first pressure chamber 38a via the first fluid line 39, whereby the transmission piston 35 moves the rotor 46. In this case, an electrical voltage is ^¬ voltage induced in the linear motor 27, which can be fed back into the electrical network or stored in an energy storage 54.

With the help of the linear motor 27, it is also possible to accelerate the blank holder ring 21 in the direction of movement of the plunger 12 prior to the impact of the upper tool 14 on the sheet holder ring 21 to reduce the relative speed between the upper tool 14 and sheet ^¬ holder ring 21 at the time of impact and to reduce the me ^¬ chanical load in the drawing press 10th In this case, the piston rod 31 of the working cylinder 29 is initially in its particular fully extended position. By movement of the rotor 46 and displacement of the transmission piston 35 to reduce the volume of the second pressure chamber 38 b in the translation unit 28, hydraulic medium is conveyed via the second fluid line 40 into the second working chamber 42 of the working cylinder, where ^{¬ is} triggered by a retraction movement of the piston rod 31. In this case, hydraulic medium from the first working chamber 41 via the first fluid line 39 in the first pressure promoted 38a space. Once the upper tool 14 touches down on the blank holder 22, the control unit 26 switches from the position control in a force control and preferably by regulating the pressure in the first working chamber 41, the desired clamping force between sheet holding ring 21 and upper tool 14, while the sheet blank 22 on the Lower tool 15 is pulled.

In the preferred embodiment of the drawing press 10, the axis B is oriented at right angles to the working direction A. Due to the smaller piston surfaces Fl, F2 of the transmission piston 35 compared to the piston surfaces F3, F4 of the working piston 30, the travel of the translation ^¬ piston 35 and thus of the rotor 46 by a factor greater by which the associated piston surfaces Fl and F3 and F2 and F4 differ. Preferably:

F3 / F1 = F4 / F2.

However, the width of the press table is sufficient to assign the linear motor 27 and the translation unit 28 ent ^¬ long a common axis B preferably horizontally ^¬ . As a result, the space in the working direction A of the drawing press 10 does not increase.

The invention relates to a drive device 19 for a secondary drive of a press and in particular a drawing press 10. The drive device 19 is insbesonde ^¬ re as a table cushion drive. It has an electric Li ^¬ nearmotor 27, the rotor 46 is rigidly connected to a transmission piston 35 of a fluidic translation unit 28. The fluidic translation unit 28 has a first pressure chamber 38 a, which is connected via a first fluid line 39 to a first working chamber 41 of a working cylinder 29. By doing that to the first Pressure chamber 38a adjacent first piston surface Fl of about ^¬ reduction piston 35 is smaller than that adjacent to the first Ar ^¬ Chamber of Labor 41 third piston face F3 of the Ar ^¬ beitskolbens a force increasing the force of the linear ^¬ motor 27 to a the ratio of the areas is achieved corresponding factor. Thus, the necessary labor forces cylinder 29 using only one linear motor 27, he ^¬ be enough.

Reference sign list:

10 drawing press

11 press frame

12 pestles

13 press main drive

14 upper tool

15 lower tool

16 press table

17 table cushions

18 floating plate

19 drive device

20 push rod

21 sheet metal retaining ring

22 sheet metal blank

26 control unit

27 linear motor

28 translation unit

29 working cylinder

30 working pistons

31 piston rod

32 free end v. 31

35 translation piston

36 housing interior

37 cylinder housing

38a first pressure chamber

38b second pressure chamber

39 first fluid line

40 second fluid line

41 first working chamber v. 29

42 second working chamber v. 29 44 memory

45 connecting element

46 runners

47 stator

50 frequency converters

51 position sensor

52 position sensor

53 pressure sensor

54 energy storage

55 rectifier

A working direction

B axis

Fl first piston surface v. 35

F2 second piston area v. 35

F3 third piston area v. 30

F4 fourth piston area v. 30

Claims

Claims:

Drive device for a press (10), in particular for a table cushion (17) of a press (10), with a linear electric motor (27), which is controlled by a control unit (26), with a translation unit (28), one in one Housing interior (36) fluidly adjacent, movable translation piston (35) which is coupled in motion with the rotor (46) of the linear motor (27), with a through the booster piston (35) in the housing interior (36) limited pressure chamber (38a), the ü - Connected via a fluid line (39) with a working chamber (41) of a fluidic working cylinder (29) of Pres ^¬ se (10).

Drive device according to claim 1,

characterized in that the fluid line (39) is designed as a rigid tube.

Drive device according to claim 1,

characterized in that the maximum working travel of the working piston (30) of the working cylinder (29) is smaller than the maximum travel of the Überset ^¬ zerkolbens (35).

Drive device according to claim 1,

characterized in that the effective piston area (Fl) of the booster piston (35) is smaller than the effective piston area (F3) of the working piston (30) of the working cylinder (29).

5. Drive device according to claim 1,

characterized in that the rotor (46) and the transmission piston (35) along a common axis (B) are arranged.

6. Drive device according to claim 1,

characterized in that the rotor (46) via a both tensile and compressive forces receiving Verbin ^¬ tion element (45) with the transmission piston (35) is connected.

7. Drive device according to claim 1,

characterized in that the linear motor (27) can operate in engine operation or in generator operation.

8. Drive device according to claim 1,

characterized in that the working cylinder (29) as a double-acting cylinder with a first working chamber (41) and a second working chamber (42) is configured and that the second working chamber (42) with a second pressure chamber (38b) of the translation unit (28) fluidly connected is.

9. Press with a press frame (11) on which a via a press main drive (13) drivable plunger (12) is movably mounted, with an on the plunger (12) arranged upper tool (14), with a press table (16) of the Press frame (11) arranged lower tool (15), with a on the upper tool (14) facing away from the press table (16) arranged table cushions (17), which has a floating plate (18) which is movable in and against the direction of movement of the plunger (12) via a working cylinder (29) of a drive device (19) according to one of the preceding claims.

Press according to claim 9,

characterized in that the linear motor (27) is arranged transversely to the direction of movement of the plunger (12) on the press frame (11) or on the press table (16).