DE102013005876A1 - Hydraulic press - Google Patents

Abstract

Disclosed is a hydraulic press with two displacement units, one of which can be coupled to a drive machine and the other to a press ram. At least one displacement unit has an adjustable displacement volume.

Description

The invention relates to a hydraulic press according to the preamble of patent claim 1.

Conventional hydraulic presses have two hydrostatic displacement units, which are fluidly connected via an inlet and a return. To generate a pressing force is one of the displacement units with a prime mover, such as an electric motor, and the other coupled to a press ram. The coupling is usually done via a coupling rod or coupling gear.

A generic hydraulic press shows the patent CH 681 872 A5 , Therein, a displacer unit is driven by an electric motor, wherein a flywheel is arranged on a drive shaft of the electric motor. The other, with the press ram coupled displacement unit is disclosed as a hydraulic cylinder but also as a hydraulic motor. To control the force of the press ram (press force) and its speed, the press has a control device with a control valve. On the one hand, the pressure medium volume flow can be throttled and limited by this from one to the other displacer unit. On the other hand, via the control valve, the pressure medium of the two working chambers of the hydraulic cylinder to invert the direction of movement of the press ram are inverted.

A disadvantage of this solution is that due to pressure losses in the control device, a significant proportion of hydraulic energy is lost and it must be recooled while warming pressure medium. This represents a considerable energy and device technical effort.

In contrast, the invention is based on the object to provide a hydraulic press with increased energy efficiency.

This object is achieved by a hydraulic press having the features of patent claim 1.

Advantageous developments of the hydraulic press are described in the claims 2 to 12.

A hydraulic press has two hydrostatic displacement units, which are fluidly connected to one another via a first inlet and a first return, in particular connected. To generate a pressing force, one of the two displacement units with a drive machine and the other of the two displacement units with a press ram coupled, in particular coupled. According to the invention, a displacement volume of at least one displacer unit, in particular for adjusting the pressing force and / or a lifting speed of the plunger, can be adjusted.

Instead of, as is customary in conventional hydraulic presses, controlling the pressurizing agent of the other displacer unit by means of a displacer unit subject to pressure loss via a throttling device, the pressurizing medium can be controlled in accordance with the invention via the adjustment of the displaced volume with low pressure loss. As a result, the press has a lower power loss and works more energy efficient. In addition, eliminates a resulting from the conventional throttling heating of the pressure medium, so that a cooling unit for its re-cooling is smaller interpretable.

Apart from that, the press according to the invention has the advantage that it has an approximately 35 to 75% higher part yield while increasing service life and a full press force is already available from a stroke rate of one.

Compared with conventional, non-generic presses, in which the press ram is driven to produce the pressing force electromechanically via a servo motor, more dynamic time courses of the pressing force and the pressing speed can be realized according to the invention. This is due to the fact that the one displacement unit has a higher adjustment dynamics than the servomotor, since components involved in adjusting the displacement volume have significantly less inertia compared to a rotor of the servomotor to be accelerated or braked. The thus more precisely controlled time course positively influences a quality of the component to be pressed. In addition, by means of an adjustment according to the invention of the displacement volume towards small values, pressure holding of the press ram with minimal drive power can be achieved. In the conventional, over the servomotor driven press ram this work can be done only by permanent, high power consumption from the mains.

Compared to this generic extraneous drive, the drive according to the invention has a cost advantage.

The other displacer unit is preferably coupled via a mechanical coupling mechanism or linkage with the press ram, in particular coupled.

A device technology particularly simple and inexpensive development of the press is given when the other displacer unit is formed with a constant displacement volume. The adjustment of a pressure medium volume flow flowing between the displacement units then takes place only via the first displacement unit. Alternatively, the other displacer unit may also have an adjustable displacement volume, whereby an even higher Verstelldynamik can be achieved.

Alternatively, the other displacer unit can be configured with an adjustable displacement volume, whereby a dynamics of the adjustment of the force and speed of the press ram can be increased.

In order to illustrate, for example, a rapid traverse of the press ram, in a preferred refinement, the other displacer unit can be coupled to an electric motor via a drive shaft, in particular coupled. The electric motor preferably has an electronic position and / or speed and / or torque control as a function of corresponding desired values of the press ram. Preferably, it is designed as a high-pole, slow-running torque servo motor.

In a preferred embodiment, the one displacer unit has a first hydrostatic hydraulic machine and a second hydrostatic hydraulic machine which can be coupled to the first via a drive shaft, in particular coupled. At least the first of the two hydraulic machines has an adjustable displacement volume. Each of the hydraulic machines has a group of hydrostatic work spaces. About the two hydraulic machines, the other displacer unit can be acted upon with a particularly large pressure medium flow, without the need for a particularly large, extra to be designed and to be built hydraulic machine must be provided. The coupling described allows the use of two standard hydraulic machines, which investment, manufacturing, storage and maintenance costs of the press can be reduced. The one displacer unit can deviate from it but also have more than two coupled hydraulic machines.

To pressurize the other displacer unit with a bundled pressure medium flow in a preferred embodiment, both hydraulic machines of a displacer unit fluidly connected in parallel with the first inlet and the first return, in particular connected.

The other displacer unit is configured particularly simple device, if it has exactly one hydraulic machine.

In a preferred embodiment, the other displacer unit also has a first hydraulic machine and a second hydraulic machine which can be coupled thereto, in particular coupled, via a drive shaft. Both first hydraulic machines and, via a second inlet and a second return, both first hydraulic machines can be fluidly connected to one another, in particular connected, via the first inlet and the first return. In addition, the second hydraulic machine of the one displacer unit has an adjustable displacement volume. In this way, each hydraulic machine of the other displacer unit can be acted upon by its associated hydraulic machine of a displacer unit via the corresponding supply and return with an individual pressure medium volume flow. This allows a very differentiated and fine control of the press ram. Preferably, the displacement volumes of the two hydraulic machines of a displacer unit are independently adjustable. One of the displacement volumes can be independent of the other zero.

In a particularly advantageous embodiment, displacement volumes of the two hydraulic machines of the other displacer unit have different sizes, wherein the displacement volume of the first hydraulic machine is greater than that of the second one. As a result, a rapid and a force cycle of the press can be implemented in device-friendly manner by the first hydraulic machine of the other displacer unit of the power stroke of the press ram with little travel and high pressing force and the second hydraulic machine of the other displacer unit of the rapid traverse of the press ram with a long travel and low pressing force can be assigned.

The press proves to be particularly dynamic and flexibly controllable if, in a further development, the displacement volume of the one displacer unit is adjustable such that a conveying direction of the one displacer unit can be reversed given the same direction of rotation of the drive machine. This reversibility of the press ram and a pendulum stroke are possible. It is advantageous that no switching valves for a reversal of the conveying direction and thus the movement or direction of rotation of the other displacer unit are necessary.

Particularly preferred, in particular for the latter purpose, is the one displacer unit, or at least one of their hydraulic machines, designed as a single or double axial piston machine with a swiveling on both sides of a neutral position, in particular durchschwenkbaren, swash plate. The neutral position is characterized by the fact that supported on the swash plate working piston or cylinder of the Axial piston machine perform no stroke and thus no promotion of the pressure medium takes place.

Alternatively, each of the displacer units may be configured as a peripheral machine or may comprise one or more hydraulic machines designed as peripheral machines.

Hydromachines of the types mentioned are proven and robust standard hydraulic components that can be controlled via equally proven control / regulating devices and methods. Through them a stable operation of the press and a low maintenance are given.

Preferably, the drive machine via at least one electric motor, in particular a three-phase motor with frequency converter is formed. In this case, the prime mover can also be modular, that is to say be formed by more than one electric motor.

In a particularly advantageous development, the one displacer unit can be coupled to the drive machine via a flywheel, in particular coupled. In this way, occurring or required force peaks of the pressing force not directly from the prime mover but can be covered by the kinetic energy of the flywheel. The prime mover can thereby be designed smaller and / or operated with less cooling. The flywheel in combination with the one displacement unit also offers a proven solution of hydromechanical energy recovery without capacitors or other electrical devices.

A particular advantage is obtained if the one displacement unit is designed as pivotable as described above, its conveying direction is thus reversible with the same direction of rotation of the drive machine. Then, a deceleration of the press ram at the end of a Pressenhubes done by swinging through. The other displacer unit goes from engine to pump operation and drives the one displacer unit. This in turn drives the flywheel, which recovers energy.

In a preferred development, the press has at least one hydraulic cylinder on which a die cushion of the press can be supported, in particular supported. For a recovery of press work / energy while a pressure chamber of the hydraulic cylinder with another hydraulic machine in pressure medium connection can be brought, which can be coupled in a first variant via a further drive shaft with the drive machine or in a second variant with an electric machine. Thus, the recovery for the first variant by a hydromechanical drive support the prime mover and for the second variant hydromechanical / electromechanical effected by a conversion of press work into electrical energy. In the latter case, the electrical energy in a network for other use or, if the drive machine is designed as an electric machine, the prime mover can be fed.

The hydraulic press can be designed in such a way that a tryout operation is made possible by means of a handwheel.

The above-described control unit preferably has a memory unit in which a control method with a desired profile of the ram speed is stored. Preferably, the control unit also has a processor unit, in which the control method can be executed, wherein the desired profile can be traced by a corresponding control of an adjustment of the one or both displacement units.

The other displacer unit can be designed as a double-acting differential cylinder as an alternative to the aforementioned design of the peripheral or piston machine.

For the press overload protection by a maximum pressure protection in the supply line device technology is simply provided via a pressure relief valve.

The first and / or second hydraulic machine preferably each has a group of hydrostatic working spaces, each of which can be fluidly connected in alternation with the inlet and return associated with the hydraulic machine.

If the one and / or the other displacer unit has two hydraulic machines, then these can be arranged together in a housing of the corresponding displacer unit, or each hydraulic machine has its own housing.

In the following, five embodiments of a hydraulic press according to the invention are explained in more detail with reference to five drawings. Show it

1 a hydraulic circuit diagram of a first embodiment of a hydraulic press,

2 a hydraulic circuit diagram of a second embodiment of a hydraulic press,

3 a hydraulic circuit diagram of a third embodiment of a hydraulic press,

4 a hydraulic circuit diagram of a fourth embodiment of a hydraulic press, and

5 a hydraulic circuit diagram of a fifth embodiment of a hydraulic press.

According to 1 has a hydraulic press 1 a displacer unit 2 and another displacer unit 4 , The displacer units 2 . 4 are over a first inflow 6 and a first return 8th Both are designed as pressure medium lines, arranged in a closed hydraulic circuit. The one displacer unit 2 is about a shoot shaft 10 with a flywheel 12 rotatably connected, or coupled. The flywheel 12 is about another shoot 14 with one on a machine carrier 16 fixed drive machine, which as electric motor 18 is designed, coupled.

The other displacer unit 4 is about a shoot shaft 20 with a press ram 22 coupled. This has for converting the rotational movement of the drive shaft in a linear movement, a connecting rod assembly and a coupling mechanism (not shown). The first feed 6 and the first return 8th are over a 2/2-way seat valve 24 Can be brought in pressure medium connection. The valve 24 is biased by a spring in a flow position and is electromagnetically actuated in its blocking position. The valve 24 Thus, in the event of a power failure, an emergency function can be achieved by hydraulic short-circuiting of the first inlet 6 with the first return 8th fulfill.

Both the first inlet 6 as well as the first return 8th are with a Nachsaugrückschlagventil 26 connected, via which they are connectable to a tank or other pressure medium reservoir.

According to the invention, the one displacer unit 2 designed with adjustable displacement. It is designed as a simple axial piston machine in swash plate construction with swing-swash plate. For detecting a swivel angle of the swash plate, it has a swivel angle sensor 28 on.

In a normal operation of the press 1 is the electric motor 18 energized and drives over the drive shaft 14 the flywheel 12 and about the shoot shaft 10 the one displacer unit 2 at. This promotes pumping fluid pressure medium from the first return 8th in the first inflow 6 , whereby in the closed hydraulic circuit the other displacer unit 4 in motor operation, the drive shaft 20 drives. This drives the press ram via a press shaft, not shown, and the connecting rods 22 so that it executes a stroke. There is a requirement to achieve a desired quality of the component to be pressed, a desired profile of the pressing force and the speed of the press ram 22 depending on the time or the stroke nachzufahren. The nominal profiles are in a control unit, not shown, of the press 1 deposited and are in the intended operation of the press 1 via a corresponding control of an adjusting device (not shown) of the one displacer unit 2 traced. In this case, the swivel angle sensor is used 28 and a sensor, not shown, on the press ram 22 the acquisition of the actual values which enter into the control.

It is particularly advantageous that the above-described control, unlike in the prior art, no throttling of the pressure medium volume flow in the first inlet 8th must be done. The control of the pressure medium volume flow takes place exclusively via the control or adjustment of the displacement volume of the one displacer unit 2 and thus low pressure loss.

For the embodiments described below 2 to 5 applies that only the differences from the first embodiment will be discussed in more detail. Otherwise, they correspond to the first embodiment. In this case, components or components which are formed over the embodiments of the same time, provided with the same reference numerals.

A press 101 has according to 2 an electric motor 130 via an unillustrated drive shaft with the other displacer unit 4 is coupled. The electric motor 130 is designed as a torque servo motor. Advantage of this embodiment is that for different gaits of the press either the other displacer unit 4 or the electric motor 130 or both together contribute to the ram motion. In the illustrated embodiment, the electric motor 130 small, or underachieving and takes over the function of a rapid traverse, in which the press ram 22 is moved with little force but high speed towards the die cushion. During the rapid traverse are the electric motor 18 and the one displacer unit 2 either driven so that the other displacer unit 4 a speed profile of the electric motor 130 without resistance, or the other displacer unit 4 is from the shoot shaft 20 decoupled so that they are the electric motor 130 do not have to lug. If the rapid traverse over into a force passage in which the component is pressed off at a lower speed but with a high pressing force, this assumes the other displacement unit 4 in already in the first embodiment according to 1 described manner.

Notwithstanding the embodiments shown so far has a press 201 according to 3 a displacer unit 202 and another displacer unit 204 , each having two with each other via a drive shaft (not shown) coupled hydraulic machines. The displacer units 202 . 204 are thus configured as a double machine. The one displacer unit 202 has a first hydraulic machine 232 and a second hydraulic machine 234 , Both are, as well as the one displacement unit 2 the previous embodiments, each designed as an axial piston machine in swash plate design with swivel swash plate and each have the aforementioned pivot angle sensor 28 for detecting the swivel angle.

The other displacer unit 204 has a first hydraulic machine 236 and a second hydraulic machine coupled thereto via a drive shaft (not shown) 238 , Both are each, as well as the other displacer unit 4 of the preceding embodiments, configured as an axial piston machine with a constant displacement volume.

The first two hydraulic machines 232 . 236 are about the first inflow 6 and the first return 8th fluidly connected. The two second hydraulic machines 234 and 238 are via a second inlet 207 and a second return 209 fluidly connected. The second inlet 207 and the second return 209 are each about an already described Nachsaugrückschlagventil 26 connectable with a tank or other pressure medium reservoir for the purpose of Druckmittelnachsaugung. Analogous to the first inlet 6 and the first return 8th trained hydraulic circuit, is the second inlet 207 with the second return 209 via an already described 2/2-way seat valve 24 connectable.

The aim of the second closed hydraulic circuit is the same, as already in the embodiment according to 2 with the help of the electric motor 130 is pursued. It applies to the express and power of the press ram 22 to provide adapted hydraulic drive machines. About the first hydraulic machine 232 the one displacer unit 202 , the first inflow 6 , the first hydraulic machine 236 the other displacer unit 204 and the first return 8th can the above-described power gear and the second hydraulic machine 234 the one displacer unit 202 , the second inflow 207 , the second hydraulic machine 238 the other displacer unit 204 and the second return 209 the above-described rapid traverse can be provided. Accordingly, the second hydraulic machine 238 with smaller displacement than the first hydraulic machine 236 designed.

Im in 4 shown fourth embodiment, the other displacement unit 4 a particularly large displacement volume. In order to still achieve a sufficient ram speed, one must with the prime mover 18 coupled displacer unit can provide a large pressure medium volume flow. In principle, there are several possibilities: On the one hand, a correspondingly large, simple displacer unit can be designed and built that meets the pressure medium requirement, on the other hand, two or more smaller hydraulic machines coupled and fluidly parallel with the first inlet 6 and the first return 8th get connected. The latter solution was according to the fourth embodiment 4 selected. Deviating from the first embodiment has a press 301 therefore instead of the displacer unit 2 according to 1 a displacer unit 202 with the first hydraulic machine 232 and the second hydraulic machine 234 , Unlike the third embodiment according to 3 but now both are hydromachines 232 . 234 with the first feed 6 and the first return 8th fluidly connected, so that analogous to the first embodiment according to 1 only a closed hydraulic circuit is formed. Thus, the other displacer unit 4 over both hydraulic machines 232 . 234 beauchlagbar with pressure medium. Advantage here is that existing, proven standard hydraulic machines are interconnected modular. In this way there are expenses in conception, planning, installation and maintenance of the press 301 minimized.

Notwithstanding the preceding embodiments is in 4 also a drawing cushion 340 the press 301 shown. The drawing cushion 340 has a designed as a double-acting differential cylinder hydraulic cylinder 342 in which a piston 344 with one-sided piston rod 346 slidably arranged. One from the piston 344 and the piston rod 346 limited annulus 348 is with a hydrostatic pressure fluid reservoir 350 fluidly connected. About this can be carried out a pre-acceleration of the component to be pressed to reduce force peaks when hitting the press ram.

From the piston 344 is still a pressure room 352 limited, the via a pressure medium line 354 with another hydraulic machine 356 is fluidically connected. This is also designed as an axial piston machine in swash plate design with swivel swash plate and has a swivel angle sensor 28 , It is connected to a tank T in the open hydraulic circuit.

About the pressure medium line 354 and the hydraulic machine 356 is on device technology simple way press work, or press energy from the press ram 22 on the piston rod 346 and the piston 344 is transmitted, recuperable. This is the hydraulic machine 356 over a drive shaft 358 with the electric motor 18 coupled. On the other hand, the electric motor 18 the hydraulic machine 356 over the drive shaft 358 drive, allowing pressure medium in the pressure chamber 352 is promoted and the piston 344 can be pushed back to its original position before a press stroke. A direction reversal of the pressure medium volume flow in the pressure line 354 takes place simply by swinging through the swash plate of the hydraulic machine 356 ,

In principle, the first three exemplary embodiments shown are also those in FIG 4 shown components for energy recovery expandable.

The fifth and final embodiment of a press 401 according to 5 corresponds to the embodiment of the energy recovery except for the embodiment 4 , Unlike this, the energy recovery in the fifth embodiment is not only on a hydromechanical, but in addition to an electromechanical way. Notwithstanding the embodiment according to 4 rejects the press 401 according to 5 a modified electric motor 418 on. This one is with an electric machine 460 via an electrical line 462 connected. The electric machine 460 is via a drive shaft arrangement 464 with a hydraulic machine 468 coupled with a pressure medium connection to the pressure chamber 352 and is connected to a tank T with its other fluid port. The hydraulic machine 468 is designed as an axial piston machine in swash plate design with swivel swash plate and has a swivel angle sensor for measuring a swivel angle 28 on. Fluidic parallel to the hydraulic machine 468 is in a pressure medium line 470 a 2/2-way proportional seat valve 472 arranged in servo construction. Here is a working port of the valve 472 with the pressure room 352 and the other working port of the valve 472 fluidly connected to the tank T. About the valve 472 can be a bypass flow from the pressure chamber 352 bypassing the hydraulic machine 468 be formed directly to the tank T. This serves to reduce possible pressure peaks during the pressing process and can reduce the quality of the force and speed profile of the die cushion 340 and thus improve the part quality.

The energy recovery takes place according to the fifth embodiment such that on the press ram 22 depressed piston 344 Pressure medium from the pressure chamber 352 is displaced and, provided the valve 472 not fully open and the hydraulic machine 472 has a swing angle not equal to zero, via the hydraulic machine 468 the displaced pressure medium is released from the high pressure to the tank pressure. This drives the hydraulic machine 468 via the drive shaft arrangement 464 the electric machine 460 in the generator mode via the electrical line 462 electrical power to the prime mover 418 can deliver.

Also in 5 shown concept of energy recovery can on the previously shown embodiments according to the 1 to 4 be applied.

The presses 1 ; 101 ; 201 ; 301 and 401 For example, they can be operated at twenty to thirty strokes per minute. A preferred translation between the press ram 22 and the other displacer unit 4 ; 204 is about 1: 5. It follows that the other displacer unit 4 ; 204 must run at about 100 to 150 rev / min. For this purpose, it is designed as a so-called slow runner.

The one displacer unit 2 ; 202 however, should be operated at a higher speed, about 1500 to 2000 rpm, on the one hand to achieve high efficiency and on the other hand with a comparatively low mass of the flywheel 12 to provide a sufficiently high kinetic energy.

Disclosed is a hydraulic press with two displacement units, one of which is coupled to a prime mover and the other with a press ram. At least one displacer unit has an adjustable displacement volume.

LIST OF REFERENCE NUMBERS

1; 101; 201; 301; 401

hydraulic press

2; 202

a displacer unit

4; 204

other displacement unit

6

First feed

8th

First return

10

drive shaft

12

flywheel

14

drive shaft

16

machine support

18; 418

prime mover

20

drive shaft

22

press ram

24

2/2-way poppet valve

26

check valve

28

Swing angle sensor

130

electric motor

207

Second feed

209

Second return

232

First hydraulic machine

234

Second hydraulic machine

236

First hydraulic machine

238

Second hydraulic machine

340

cushion

342

hydraulic cylinders

344

piston

346

piston rod

348

annulus

350

hydraulic accumulator

352

pressure chamber

354

Pressure medium line

356

hydromachine

358

drive shaft

460

hydromachine

462

Pressure medium line

464

Drive shaft arrangement

468

hydromachine

470

Pressure medium line

472

2/2-way proportional directional poppet valve

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• CH 681872 A5 [0003]

Claims (12)

Hydraulic press with two hydrostatic displacement units ( 2 . 4 ; 202 . 204 ), which have a first inflow ( 6 ; 207 ) and a first return ( 8th ; 209 ) are fluidically connectable to each other, wherein for generating a pressing force a ( 2 ; 202 ) of the two displacement units ( 2 . 4 ; 202 . 204 ) with a prime mover ( 18 ; 418 ) and the other one ( 4 ; 204 ) of the two displacement units ( 2 . 4 ; 202 . 204 ) with a press ram ( 22 ), characterized in that a displacement volume of at least one displacer unit ( 2 ; 202 ) is adjustable. Press according to claim 1, wherein the other displacer unit ( 4 ; 204 ) has a constant displacement volume. Press according to claim 1 or 2, wherein the other displacer unit ( 4 ) via a drive shaft with an electric motor ( 130 ) can be coupled. Press according to one of the claims 1 to 3 , wherein the one displacer unit ( 202 ) a first hydrostatic hydraulic machine ( 232 ) and, with this via a drive shaft coupled, second hydrostatic hydraulic machine ( 234 ), of which at least the first ( 232 ) has an adjustable displacement volume. Press according to claim 4, wherein the first hydraulic machine ( 232 ) and the second hydraulic machine ( 234 ) of a displacer unit ( 202 ) fluidly in parallel with the first inlet ( 6 ) and the first return ( 8th ) are connectable. Press according to one of the preceding claims, wherein the other displacer unit ( 4 ) has exactly one hydraulic machine. Press according to claim 4, wherein the other displacer unit ( 204 ) a first hydraulic machine ( 236 ) and with this via a drive shaft coupled, second hydraulic machine ( 238 ), and wherein over the first feed ( 6 ) and the first return ( 8th ) both first hydromachines ( 232 . 236 ) and via a second feed ( 207 ) and a second return ( 209 ) both second hydraulic machines ( 234 . 238 ) are fluidically connectable to each other, and wherein the second hydraulic machine ( 234 ) of a displacer unit ( 202 ) has an adjustable displacement volume. Press according to claim 7, wherein a displacement volume of the first hydraulic machine ( 236 ) of the other displacer unit ( 204 ) greater than a displacement volume of the second hydraulic machine ( 238 ). Press according to one of the preceding claims, wherein the displacement volume of the one displacer unit ( 2 ; 202 ) is adjustable so that at the same direction of rotation of the drive machine ( 18 ; 418 ) a conveying direction of the one displacer unit ( 2 ; 202 ) is reversible. Press according to one of the preceding claims, wherein the drive machine ( 18 ; 418 ) is formed via an electric motor. Press according to one of the preceding claims, wherein the one displacer unit ( 2 ; 202 ) via a flywheel ( 12 ) with the prime mover ( 18 ; 418 ) can be coupled. Press according to one of the preceding claims with at least one hydraulic cylinder ( 342 ), on which a die cushion ( 340 ) is supportable, wherein a pressure chamber ( 352 ) of the hydraulic cylinder ( 342 ) with another hydraulic machine ( 356 ; 468 ) can be brought into pressure medium connection, which via a further drive shaft ( 358 ) with the prime mover ( 18 ), or with an electric machine ( 460 ) can be coupled.

Images