ES2865726T3 - Hydraulic press drive - Google Patents

Abstract

Hydraulic press drive for a mold part, which can be moved by means of a fast-running cylinder arrangement (10) of the press drive to accelerate and which can be ordered by means of a holding cylinder arrangement (6) of the drive press with a holding pressure, wherein the holding cylinder arrangement (6) and the fast-running cylinder arrangement (10) are arranged in each case in circuits hydraulically separated from each other with in each case a hydraulic machine ( 30, 62), characterized in that the hydraulic machine (62) arranged in a fast-running branch (2) consists of a plurality of hydraulic machine units (62a, 62b, 62c) connected in parallel, which can be individually operated, in together or in any combination.

Description

DESCRIPTION

Hydraulic press drive

The invention relates to a hydraulic press drive according to the characteristics of the preamble of claim 1. Such a hydraulic press drive is used in a press to form a work piece clamped in a mold part, wherein this piece of The mold can be moved by means of a drive relative to another mold part.

The basic structure of such sheet metal forming presses is known, for example, from DE 43 09 641 A1 or DE 103 36 279 A1. Document EP-A-0074421 discloses a hydraulic press drive according to the characteristics of the preamble of claim 1

In such presses, the forming of the sheet takes place by means of a mold, the upper mold part of which can be moved through a mechanical or hydraulic main drive. The sheet to be formed is supported in a sheet holder of the lower mold part. As the upper mold part moves downwards, the lower mold part, supported on a dolly, with the plate clamp is accelerated by means of a hydraulic drive to the travel speed of the upper mold part, so that the mechanical loads in the moment of closing the mold are minimal. During the shaping operation, both mold parts move at approximately the same speed, a holding force being applied through a holding cylinder on the lower mold part. To demold the workpiece, the two mold parts are activated in such a way that the mold is opened and the shaped workpiece can be removed.

The movement profiles of the mold parts, established according to the above explanations, are represented, for example, in FIG. 2 of DE 10336279 A1. In known solutions, during the controlled lowering of the dolly, the pressure medium coming out of the retaining cylinder is fed to a hydraulic machine, so that the hydraulic energy can be used to drive other consumers.

In the textbook "Handbuch der Umformtechnik"; Springer Verlag Berlin Heidelberg, 1996, pages 44 ff., A hydraulic press drive of this type is also shown, in which the nose pad is accelerated during the lowering movement of the upper mold part (die) and then regulated as desired holding pressure during shaping operation.

In these solutions it is disadvantageous that the acceleration and retention take place via components arranged in a common hydraulic circuit, the acceleration often taking place also via a retention cylinder, so that in the feedback described above, during the Retention also has to take into account the supply of sufficient pressure medium to the other components and, correspondingly, a commitment to feedback control is required. Rather, the invention is based on the objective of creating a hydraulic press drive, in which the efficiency of hydraulic energy conversion during feedback is improved.

This objective is achieved by means of a hydraulic press drive with the characteristics of claim 1.

Advantageous developments of the invention are the subject of the dependent claims.

According to the invention, the hydraulic press drive has a mold part that holds a workpiece, which can be moved by means of at least one fast-running cylinder for acceleration and which can be requested by means of a holding cylinder with a holding force, in which the holding cylinder and the fast-moving cylinder each have their own hydraulic circuit associated with each other with a hydraulic machine for supplying the pressure medium.

Due to the realization of the press drive with two hydraulic circuits separated from each other for the arrangement of the holding cylinder and the fast-moving cylinder, the supply of pressure medium can be controlled with a view to the optimized conversion of hydraulic energy for the actuation of hydraulic machines largely independently of each other. In this way it is possible that the illustrated feedback, with which the pressure medium exiting the holding cylinder is evacuated through the hydraulic machine of the corresponding circuit to the tank, is controlled in such a way that, for example, the mode feedback is chosen when there is a high power consumption, while in the case of low power consumption a feedback is dispensed with. In this way, the use of the hydraulic energy of the pressure medium exiting the holding cylinder (s) can be optimized independently of the activation of the high-speed cylinder, so as to ensure energy-efficient operation of the press.

In a particularly preferred embodiment, a pressure chamber, acting in the retention direction, of the holding cylinder can be connected, via a releasable check valve, to the reservoir, in order to be able to reduce the holding pressure or to be able to switch quickly between high speed and holding.

According to the invention it is preferred that this non-return valve is pilot controlled, so that rapid switching can be ensured.

In a variant of the invention, a hydraulic accumulator arrangement is provided in the pressure line between the pressure chamber, active in the holding direction, of the holding cylinder and the associated hydraulic machine, which is charged in the feedback mode .

This accumulator arrangement can be associated with an accumulator switching valve arrangement with a fast-switching accumulator switching valve which, in a passage position, opens a pressure medium connection between the active pressure chamber in direction and the reservoir and, in a locked position, closes this pressure medium connection in the direction of the reservoir.

Preferably, a plurality of non-return valves connected in parallel are also arranged in this pressure line, which admit a large volumetric flow of pressure medium to discharge the hydraulic accumulator arrangement.

The high-speed drive is realized I according to the invention with a plurality of hydraulic machine units connected in parallel, which can preferably be mechanically coupled to each other, so that the supply of pressure medium to the high-speed cylinder arrangement it takes place through several small, inexpensive units with good reaction behavior.

In this regard, it is preferred that these units are designed with reversible suction / transport direction or that the pressure medium supply direction takes place via a distributor valve arrangement.

In an embodiment of the invention, the fast-running cylinder arrangement is made with at least one differential cylinder with different active surfaces, where the smallest active surface can be connected to the pressure tap of the hydraulic machine arrangement of the Fast-running drive and the largest active surface can be connected, through this last-mentioned distribution valve, with this pressure tap or with the reservoir. In this way, the direction of travel of the high-speed cylinder arrangement can be easily adjusted by switching the directional valve.

In a variant, provision is made to provide hydraulic accumulators in the hydraulic circuit associated with the high-speed cylinder arrangement, between the hydraulic machine arrangement and the high-speed cylinder arrangement.

The complexity of the implementation of hydraulic machines can be minimized if, in the feedback mode, the hydraulic machine associated with the holding drive drives a hydraulic machine associated with the high-speed drive.

In this regard, it is preferred that the hydraulic machine associated with the holding drive has a constant displacement motor, which drives a variable displacement pump, through which a variable displacement motor of the hydraulic machine is in turn driven in the high-speed circuit, which in turn drives a variable displacement pump for supplying pressure medium to the high-speed cylinder arrangement.

In this variant, a distributor valve can be arranged in the pressure medium flow path between the two variable displacement motors, through which pressure medium can be taken in for supplying pressure medium to other consumers.

The invention can be applied in a particularly advantageous manner if the press drive is implemented with a control device by means of which the accumulator switching valve and / or the releasable non-return valve is switched when a pressure threshold is exceeded in the pressure chamber. , active in the holding direction, of the holding cylinder arrangement for feedback.

This switching can take place in a switched or pulsed manner.

Preferred embodiments of the invention are explained in more detail below with the aid of schematic drawings. They show:

FIG. 1 is a circuit diagram of a first embodiment of a hydraulic press drive;

Figure 2 a variant of a press drive and

Figure 3 shows a third embodiment of a press drive.

The invention is explained below with the aid of a hydraulic press for sheet metal forming or deep drawing; However, in principle it can also be applied to other types of press or machine tools. Such a press has a two-part mold, in which the workpiece to be shaped is formed. An upper part of the mold, not shown in FIG. 1, is configured as a matrix. The press has a mechanical or hydraulic main drive, to drive a drawing plunger supported by the upper mold part. The other lower part of the mold usually constitutes a punch, also called a pressing punch, which, when the mold is closed, penetrates the die. In this connection, the workpiece thus formed is fixed in place via a plate holder. This and the press punch (punch) are mounted on a press bed so that they can also move in the vertical direction. The lower part of the mold (punch) is supported on a hydraulic dolly 1, the hydraulic drive of which is represented in figure 1. This hydraulic drive consists, in principle, of a fast-moving drive 2 and a holding drive 4, which they are arranged in each case in their own hydraulic circuit. According to the invention, the actuation of the dolly is therefore carried out as a double-circuit system, the control of the components located in the respective circuit being able to take place in a way that is largely independent of the control of the components located in the other. circuit, so that, in particular, the feedback explained in the hydraulic power principle during retention can be effected with great efficiency, although this will be explained in more detail below.

The retention drive 4 has a retention cylinder 6 acting on the nose 1, with a plunger 8 having a large diameter compared to a fast-moving cylinder 10 described below. Figure 1 shows, by way of example, a holding cylinder 6 and a fast-moving cylinder 10 (obviously, the actuation of the dolly can also be carried out with several holding or fast-moving cylinders).

The retaining cylinder 6 has a pressure chamber 12 delimited by the plunger 8, which becomes smaller as the nose 1 lowers the lower mold part. This lowering takes place due to the very high weight of the lower mold part and the nose piece 1. The elevation towards the upper mold part takes place by feeding pressure medium into the pressure chamber 12 and by means of a controlled closure of this chamber. pressure 12 with respect to a tank T. The pressure chamber 12 is connected, through an unblockable non-return valve 14 and a tank line 16, with this tank T. According to the representation in figure 1, this valve non-return valve 14 allows a new suction of pressure medium from the tank T when unfolding the retention cylinder 6.

The releasable non-return valve 14 is designed as a pilot-controlled valve and has a pilot valve 18, which is designed as a 3/2-way switching valve and whose working port A is directed towards a control port of the non-return valve 14. A tank port T is connected, via a tank control line 20, to the tank T and an inlet port P is connected to a pressure control line 22. The pilot valve 18 is designed as a poppet valve. fast switching, so that a leak-free closure of the respective control line sections is possible. In a spring-preloaded basic position b, the tank port T is closed and the working port A is connected to the pressure port P. By actuating a switching magnet, the pilot valve 18 can switch to a switching position at the one which the outlet port A with is connected to the tank port T. In this switching position a, the valve 14 acts as a normal non-return valve. By switching to its basic position b shown, the non-return valve 14 is unblocked so that pressure medium can escape from the pressure chamber 12 into the reservoir T.

The pressure chamber 12 is further connected, via a pressure line 24, to a hydraulic accumulator arrangement 26, consisting, for example, of one or a plurality of hydraulic accumulators connected in series, in the example of represented embodiment of five hydraulic accumulators. The pressure line 24 empties downstream of the hydraulic accumulator 26 into a working line 28, which leads to the tank T and in which a hydraulic holding machine 30 is arranged, which can work as a pump and also as a motor. In the embodiment shown, the hydraulic machine 30 is made with a motor 32 with a variable number of revolutions, which either drives the hydraulic machine 30 (pump) or is driven by it (hydraulic motor). When the non-return valve 14 is closed and the pressure chamber 12 is getting smaller, pressure medium can therefore escape through the hydraulic machine 30 into the tank T. In this case, the hydraulic machine 30 is actuated, accordingly. so that via the motor 32 energy can correspondingly be supplied to an additional consumer. In this mode, the hydraulic accumulator arrangement 26 is also loaded. To prevent unwanted discharge of this hydraulic accumulator arrangement 26 when deploying the retaining cylinder, in the pressure medium flow path between the pressure chamber 12 and the arrangement From hydraulic accumulator 26, a check valve arrangement 34 is realized with a plurality of check valves connected in parallel; in the present case with five non-return valves. The holding pressure is determined during feedback, among other things, through the hydraulic holding machine 30.

The check valve arrangement 34 is part of an accumulator switching valve arrangement 36, indicated in FIG. 1, which, in addition to the check valve (s) 34, also has a switching valve cylinder 38, which is designed as a fast-acting 2/2-way valve. This accumulator switching valve 38 is arranged in a discharge line 40 which branches off from the pressure line 24 and opens into the tank T. In a spring-preloaded basic position b of the accumulator switching valve 38, there is no represented in FIG. 1, this pressure medium connection is open towards the tank T, so that the pressure medium can also leave the pressure chamber 12 towards the tank T when the non-return valve 14 is closed. By means of the electrical and / or hydraulic switching of the accumulator switching valve 38, it is switched to the shown switching position a, in which a backflow of pressure medium from the tank T into the pressure chamber 12 ( although a pressure medium flow is blocked in the opposite direction). This accumulator switching valve 38 is also designed as a leak-free poppet valve. In principle, with such a structure, the releasable non-return valve 14 could also be dispensed with, since the pressure medium connection of the tank 12 can also be switched via the accumulator switching valve 38.

Provided in the pressure line 24 is, in the illustrated embodiment, a protection block 42 for the accumulator arrangement 26. This protection block 42 has a pressure limiting valve 44 and a switching valve 46 connected in parallel to the same, through which, when an accumulator pressure is exceeded, which is detected for example via a measuring sensor 48, a pressure medium connection can be opened from the pressure line 24 to a reservoir line 50 The protection block 42 also has, in addition, a manual valve 48 for the manual opening of this pressure medium connection.

The high-speed cylinder 10 is designed, in this illustrated embodiment, as a synchronous cylinder with a synchronous piston 52, which delimits two annular chambers 54 and 56 with equal active surfaces. The two annular chambers 54, 56 are connected in each case, via a working line 58 and 60 respectively, to a hydraulic machine arrangement 62. This hydraulic machine arrangement 62 has, in the illustrated embodiment, several ( rather, three) hydraulic machines 62a, 62b, 62c, which can work as a pump and also as a hydraulic motor and whose transport / suction direction is reversible. In the illustrated embodiment, each of the hydraulic machines is made with a variable speed drive motor 64 which, in pump mode, drives the respective hydraulic machine and, in motor mode, is driven.

Instead of the variable speed drive, a hydraulic machine pivoting more than 0 can also be used, for example an axial piston machine or a plurality of such axial piston machines.

For protection, there are arranged in the pressure medium connections between the two working lines 58, 60 a pressure limiting valve 66 which limits the pressure in the working line 60 and a pressure limiting valve 68 which limits the pressure in the work line 58, respectively. In parallel to these two pressure limiting valves 66, 68 a 2/2-way floating position valve 70 is arranged in a bypass line 72 connecting the two working lines 58, 60. This floating position valve 70 is prestressed towards a closed position b and can be switched electrically and / or hydraulically to a switch position a, in which the two working lines 58, 60 are directly connected to each other, so that the fast-moving cylinder 10 is operated in a floating position, in which the pressure medium is moved almost without loss between the two annular chambers 54, 56.

The two working lines 58, 60 are connected in each case, through a non-return valve 74, 76, to a supply line 78 which through another non-return valve 80 is connected to a pressure connection of a supply pump 82. The pressure in the supply line 78 is limited by a supply pressure limiting valve 84. Another protection block 86 is provided in the supply line 78, and the pressure in this area can be detected through a sensor pressure 88. The protection block 86 has, in principle, the same structure as the protection block 42. Additionally, a hydraulic supply accumulator 90 is also provided, which can be connected by opening a manual valve 92 with the line power supply 78 or with the two working lines 58, 60.

According to the above explanations, the rapid travel circuit 2 is designed as a closed hydraulic circuit, in which, depending on the direction of transport of the hydraulic machine arrangement 62, pressure medium can be extracted from one of the annular chambers 54 , 56 and transported to the other pressure chamber 56, 54, in order to move the rapid traverse cylinder 10 upwards (towards the upper mold part, not shown) or downwards. Due to the small active surface of the fast-running cylinder 10 compared to the holding cylinder 6, and the high conveying power of hydraulic machines, the dolly 1 can be accelerated very quickly. In accordance with the invention, individual hydraulic machines 62a, 62b, 62c can be activated individually, together, or in any combination. In principle it is also possible to create hydraulic machines with different transport / suction volumes. As already explained, the hydraulic machines 62 can also be operated in motor mode, where, for example, in the event of lowering of the nose piece 1 caused by the high own weight, the pressure medium exits the annular chamber. 56, which is made smaller, through the hydraulic machine arrangement 62, towards the other pressure chamber 54, which is made larger, and then the hydraulic machines 62 are correspondingly driven and consequently the motors are driven drive 64, so that this energy can be used to drive other components.

To press a workpiece, for example, a plate is placed on the plate holder, not shown, which is oriented towards the highest point of the punch. The upper mold part (die) has been moved through the main drive to its top dead center. The nose piece 1 is also in the area of its upper dead center, but the two mold pieces are spaced from one another. At this top dead center, the pressure chamber 12 has its maximum volume and the pressure medium is drawn in via the releasable non-return valve 14 and / or the accumulator switching valve 38, which is in the switching position a. from reservoir T to pressure chamber 12 as retaining cylinder 6 unfolds.

At the beginning of the work cycle, the upper mold part (die) is then moved downwards. After a certain stroke of the upper mold part, the dolly 1 is accelerated downwards by a corresponding actuation of the hydraulic machine arrangement 62; consequently, pressure medium is drawn from the annular chamber 56 of the fast-moving cylinder 10 and conveyed to the annular chamber 54. The dolly 1 is accelerated in such a way that, when closing the mold, the relative velocity between both pieces of mold (die, punch) is very low or equal to 0, so that the closing operation takes place relatively smoothly and there is no fear of shocks and, thus, damage to the plate holder or the mold or the components of the press.

During the acceleration of the nose piece 1 downwards, which is favored by the high self-weight of the nose piece 1 and of the lower mold part, the non-return valve 14 or / and the accumulator switching valve 38 is unblocked or open, so that the pressure medium is expelled essentially without losses from the pressure chamber 12, which becomes smaller, towards the reservoir T. However, during the shaping operation, the pressure medium connection of the pressure chamber 12 is closed relative to tank T, so that a holding pressure builds up in the pressure chamber 12, which can be regulated with a predetermined profile by a corresponding actuation of the pilot valve 18 and via the hydraulic holding machine 30. In a possible procedural control, switching between high-speed and holding can be controlled, for example, essentially via pilot valve 18, the switch valve then remaining on utation of accumulator 38 in its closed position a shown.

The pressure medium that exits the pressure chamber 12 via the pressure line 24 during retention charges, when the accumulator switching valve 38 is in its switching position a, the hydraulic accumulator arrangement 26 and exits through the hydraulic holding machine 30 until it reaches the tank T, so that this drives the motor 32 and this energy can be used to drive other consumers. The non-return valve arrangement 34 ensures a sufficient flow cross section in this case, so that a relatively large volumetric flow of pressure medium can flow out.

In the event that the holding pressure in the pressure chamber 12 is too low or a charging of the accumulator arrangement 26 is not desired, the accumulator switching valve 38 is switched to its passage circuit b (basic position), so that the pressure medium exits the pressure chamber 12, bypassing the accumulator arrangement 26 and the hydraulic holding machine 30, towards the tank T. The accumulator switching valve 38 is designed as a fast switching valve, so that switching can take place intermittently very quickly and also with high frequency and the desired holding pressure profile can be set.

According to the invention it is preferred that the above-described feedback of the pressure medium from the pressure chamber 12 through the hydraulic holding machine 30 only takes place when the pressure in the pressure chamber 12 exceeds a predetermined value, so that hydraulic power can be converted more efficiently. This feedback as a function of the pressure in the pressure chamber 12 is not possible without more in the solutions described at the beginning, since in them the hydraulic components for accelerating and for reducing the holding pressure are arranged in the same hydraulic circuit.

In the embodiment described above, the pressure medium exits during the feedback through the hydraulic holding machine 30 to the tank T. Figure 2 shows an embodiment of the invention in which the hydraulic machine 30 arranged in the holding circuit 4 operates the hydraulic machine 62 of the fast-running circuit 2. For the sake of simplicity, in the explanation of the embodiment according to FIG. 2, the components that correspond to the embodiment according to FIG. Figure 1, are provided in each case with the same references. The latching circuit 4 of the exemplary embodiment according to FIG. 2 has essentially the same structure as the latching circuit 4 of the exemplary embodiment explained with the aid of FIG. 1, so that only the components that differ and are explained, otherwise, it refers to the previous explanations. In the variant according to FIG. 2, the fast-moving cylinder 10 is arranged above the holding cylinder 6, the plunger 8 of which again delimits the pressure chamber 12 and is also part of a holding piston 94, but It is not designed as a synchronous piston, but rather has different active surfaces, the plunger 8 passing through a bottom 96 between the holding cylinder 6 and the high-speed cylinder 10 and, together with a piston collar, delimiting the holding piston 94 annular chamber 56 active in the deployment direction, the cross-sectional area of which is essentially greater than that of annular chamber 54 located along the above the plunger collar.

The pressure in the pressure chamber 12 is sensed through a pressure sensor 98 and communicated to the control. The arrangement of the releasable check valve 14 with the pilot valve 18, the accumulator switching valve 38, the check valve arrangement 34 and the hydraulic accumulator arrangement 26 corresponds to that of the previously described embodiment, so no further explanation is necessary. One difference is that the accumulator switching valve 38 is stressed in the direction of its basic position b, in addition to the spring, also by the pressure in the pressure control line 22. The hydraulic holding machine 30 is switched on, As already explained, with the hydraulic machine arrangement 62 made by means of a single variable displacement pump 62, whose intake P is connected, through a pressure channel 100, with the two working lines 58 and 60, which open in this exemplary embodiment together in the pressure channel 100. This pressure channel 100 branches off between the hydraulic holding machine 30 and the non-return valve 118 of the pressure line 120.

In the illustrated embodiment, a distributor valve 102 is arranged in the working line 60 leading to the annular chamber 56 with a larger active surface, which is designed as a 3/3-way valve, which is electrically adjustable and / or hydraulically. The hydraulic activation of the distribution valve 102 takes place through control taps y, x, the control tap y being connected through a control line 104 with the tank T and the control tap x through a control line pressure 106 with the pressure channel 100. In the pressure control line 106 a control oil filter 108 is provided.

In order to avoid pressure fluctuations during the acceleration of the dolly 1, a fast-moving accumulator arrangement 110 is furthermore provided in the pressure channel 100.

In a represented basic position of the distributor valve 102, it connects the working lines 58, 60 with a floating position line 112, which opens into the tank T, being provided in the working line 60 and in the floating position line 112 in each case a damping butterfly 114, 116. By switching the distribution valve 102 to its position indicated with a, the working line 60 is connected with the annular chamber 56, so that in both annular chambers 56, 54 there is the The same pressure, ie the pressure in the pressure channel 100. Due to the difference in surface area, the high-speed cylinder then unfolds upwards. By switching the distributor valve to the position indicated with b, the annular chamber 56 with the largest active surface is connected through the floating position line 112 with the reservoir; Since the other annular chamber 54 is always loaded with pressure in the pressure channel 100, the high-speed cylinder 10 retracts, but then either the non-return valve 14 or the accumulator switching valve 38 must be unblocked or switched to its open position, so that the pressure medium, as explained, can be expelled essentially without loss from the pressure chamber 12 and no holding pressure builds up. The respective switching position of the directional valve 102 is detected and communicated to the control of the press. The hydraulic holding machine 30 and the hydraulic machine 62 designed as a variable displacement pump are connected, both, with the motor 32, which is driven depending on the load situation or else it also drives the hydraulic machine 62 and the hydraulic holding machine. retention 30.

The mode of operation corresponds to that of the embodiment described above. To accelerate the dolly 1, not shown in figure 2, the releasable non-return valve 14 is opened via the pilot valve 18 (alternatively the accumulator switching valve 38 can be opened) and the distributor valve 102 is adjusted to its closed position. b, in which the annular chamber 56 is pressure-relieved, so that the holding piston 94 and thereby the dolly is accelerated in the direction of movement of the upper mold part (die). To build up the holding pressure, the directional valve 102 is switched to its floating position (basic position) and the holding pressure in the pressure chamber 12 is regulated by corresponding actuation of the accumulator switching valve 38 and / or or of the releasable non-return valve 14 and, in this case, when a predetermined pressure range is reached, which is energetically favorable for feedback, the pressure chamber 12 is switched in such a way that the hydraulic accumulator arrangement 26 is charged and the medium pressure exits through the hydraulic holding machine 30 to the reservoir T and, in this respect, drives the hydraulic machine 62, in order to charge the accumulator 110, through which the annular chambers 54, 56 can be urged with a constant pressure as a function of the switching of the directional valve 102.

Figure 3 shows a variant of the exemplary embodiment according to figure 2, in which the representation of the individual components has been simplified. The holding circuit 4 corresponds essentially to the previously described embodiment, the holding cylinder 6 and the fast-moving cylinder 10 being made as in the embodiment described at the beginning, that is, the holding cylinder 6 is made as a plunger cylinder with a plunger 8 and the high-speed cylinder 10 as a synchronous cylinder with a synchronous plunger 52, the plunger rod delimiting the annular chamber 54 is connected to or in contact with the plunger cylinder 8. The pressure chamber 12 of the synchronous cylinder 6 can be connected, via the releasable non-return valve 14, with the tank T. This non-return valve 14 can be equipped, as in the previously described embodiments, with a pilot control. The non-return valve arrangement 34 and the non-return valve arrangement are again arranged in the pressure line 24 branching off the pressure chamber 12. accumulator 36. In addition, the pressure medium exits, during the feedback, through the hydraulic holding machine 30 realized as a pump with two conveying directions and a non-return valve 118 that opens in the direction of the tank T, towards the tank T. In the same way as in the previously described embodiments, the pressure line 24 can be connected to the tank T through the accumulator switching valve 38, avoiding the accumulator arrangement 36 and the hydraulic holding machine 30.

The hydraulic holding machine 30 is mechanically coupled to an adjustable hydraulic machine 120, which is designed, in the embodiment shown, as a pump with two conveying directions. Furthermore, the motor 32 is located on the same axis, which can be driven by means of the hydraulic motor 30 or it drives the hydraulic motor and / or the pump 120.

Analogously to the embodiment described above, a pressure tap P of the adjustable hydraulic machine 120 is connected to the pressure channel 100, in which a fast-moving accumulator arrangement 110 is again arranged with, in this example of embodiment, three hydraulic accumulators. The pressure channel 100 leads, in this exemplary embodiment, to the pressure tap P of an adjustable hydraulic motor 124, through which a variable displacement pump can be driven, which functionally corresponds to the hydraulic machine arrangement 62 and Therefore, it is also endowed with the same reference. On the same axis is located the drive motor 64, which can either be driven by the hydraulic motor 122 or drives the machines 122, 62.

The two intakes of the hydraulic machine 62 are connected, as in the previously described embodiments, with the working line 58 and 60, respectively, so that, depending on the direction of transport of the hydraulic machine 62, medium is transported. pressure to either annular chamber 54 or annular chamber 56 and, correspondingly, is withdrawn from the other pressure chamber in each case. The other intake of the hydraulic motor 122 made with two suction volumetric flow directions is connected through an outlet channel 124 with the tank T.

The previously described adjustable hydraulic machines 120, 122, 62 can be realized in any way, for example as axial piston machines with adjustable pivot angle.

According to the representation in FIG. 3, a supply line 124 branches out of the pressure channel 100, which is led to the pressure tap P of a continuously adjustable consumer valve 126. A tank outlet T of this consumer valve 128 is connected, through a tank channel 130, with the tank T. Two working outlets A, B are connected through working channels 132, 134 with outlets of a hydraulic consumer, not shown. In the illustrated spring-loaded basic position of the consumer valve 128, the taps A, B, P and T are connected to each other in a floating position. When switching in direction to position a, working port B is connected to pressure port P. Correspondingly, when moving in direction b, the pressure medium connection between pressure port P and pressure port is opened. working port A and, correspondingly, the work port B is connected to the tank port T. In this way it is possible to supply, through the variable displacement pump 120 driven during the feedback by the hydraulic holding machine 30, already through accumulator arrangement 110, means of pressure to other consumers.

The operating mode of the exemplary embodiment according to FIG. 3 corresponds to that of the exemplary embodiment of FIG. 2. To accelerate the dolly, the releasable non-return valve 14 and / or the accumulator switching valve 38 are opened, so that the pressure chamber 12 is connected with the tank T and the pressure medium can be expelled from the pressure chamber 12. The variable displacement pump 62, pivoting more than 0, is adjusted in such a way that pressure medium is conveyed into the annular chamber 54 and is removed from the annular chamber 56. Consequently, the dolly is accelerated by means of the rapid-travel cylinder 10. During shaping, the holding pressure in the pressure chamber 12 is regulated by a corresponding actuation from the releasable non-return valve 14 and / or from the accumulator switching valve 38 and / or from the variable displacement pump 120 and, with correspondingly high energy consumption in the cylinder of latch 6, the predetermined feedback is performed, in order to charge the accumulator arrangement 36 and drive the hydraulic latch machine 30.

As in the previously described embodiments, the feedback mode can be switched continuously at a certain pressure threshold in the pressure chamber 12 or in the form of pulse modulation, in order to ensure optimum energy conversion.

A hydraulic press drive has been disclosed with a high-speed cylinder and a holding cylinder, which are arranged in each case in a separate hydraulic circuit with a hydraulic machine.

List of references

1 lollipop

2 high speed drive

holding drive

holding cylinder

plunger diver

high speed cylinder

pressure chamber

non-return valve, releasable

deposit line

pilot valve

tank control line

pressure control line

pressure line

hydraulic accumulator arrangement

work line

hydraulic holding machine

motor

check valve arrangement

storage tank switching valve arrangement storage tank switching valve

discharge line

protection block

pressure limiting valve

switching valve

Manual valve

deposit line

synchronous plunger

ring chamber

ring chamber

work line

work line

hydraulic machine layout

drive motor

pressure limiting valve

pressure limiting valve

floating position valve

bypass line

check valve

check valve

power line

check valve

feed pump

supply pressure limiting valve protection block

pressure sensor

hydraulic accumulator supply

Manual valve

retention plunger

bottom

pressure sensor

pressure channel

distribution valve

control line

pressure control line

control oil filter

fast running accumulator arrangement

floating position line

damping butterfly

damping butterfly

check valve

adjustable hydraulic machine

hydraulic engine

flow outlet line

supply line

consumer valve

warehouse channel line of work line of work

Claims (1)

1. Hydraulic press drive for a mold part, which can be moved by means of a fast-running cylinder arrangement (10) of the press drive to accelerate and which can be ordered by means of a holding cylinder arrangement (6) of the press drive with a holding pressure, wherein the holding cylinder arrangement (6) and the high-speed cylinder arrangement (10) are arranged in each case in hydraulically separated circuits from each other with in each case a machine hydraulic machine (30, 62), characterized in that the hydraulic machine (62) arranged in a fast-running branch (2) consists of a plurality of hydraulic machine units (62a, 62b, 62c) connected in parallel, which can be operated individually , together or in any combination. Press drive according to claim 1, with a releasable non-return valve (14), via which a pressure chamber (12), active in the holding direction, of the holding cylinder arrangement (6 ) with a tank (T) or close with respect to it. Press drive according to claim 2, wherein the releasable check valve (14) is pilot controlled. Press drive according to one of the preceding claims, wherein a hydraulic accumulator arrangement (26) is provided in a pressure line (24) between a hydraulic holding machine (30) and the pressure chamber (12). Press drive according to claim 4, with an accumulator switching valve (38), via which a pressure medium connection of the pressure chamber (12) with respect to the container (T ). Press drive according to claim 4 or 5, wherein a non-return valve arrangement (34) is provided in a pressure medium flow path between the hydraulic accumulator arrangement (26) and the pressure chamber (12). which opens towards the hydraulic accumulator arrangement (26). Press drive according to claim 1, wherein the hydraulic machine units (62a, 62b, 62c) are mechanically coupled. Press drive according to claim 1 or 7, wherein the hydraulic machines (62) in the fast-running branch (2) are made with reversible transport / suction direction or can be connected through a distributor valve (102) with pressure chambers (54, 56) of the high-speed cylinder arrangement (10). Press drive according to claim 8, wherein the fast-running cylinder arrangement (10) has a differential cylinder with different active surfaces, the smallest active surface being able to be requested with the pressure at the outlet of the hydraulic machine (62 ) arranged in the fast-running branch (2) and the largest active surface, through the distributor valve (102), with reservoir pressure and with the same pressure as the smallest active surface. Press drive according to one of claims 1 to 9, wherein in the pressure medium flow path between the hydraulic machine (62) associated with the high-speed branch (2) and the high-speed cylinder arrangement ( 10) a fast-moving accumulator arrangement (110) is provided. Press drive according to one of the preceding claims, wherein the hydraulic holding machine (30) arranged on the holding leg (4) directly or indirectly drives the hydraulic machine (62) arranged on the fast-running leg (2 ). Press drive according to claim 11, wherein the hydraulic holding machine (30) arranged on the holding branch (4) is designed as a motor that drives a hydraulic machine (120) that can be adjusted to the fast-moving branch (2) , which in turn drives an adjustable hydraulic motor (122), which is in active connection with ^{the hydraulic machine (} 62 ^{) to supply pressure medium to the rapid traverse cylinder arrangement (10).} Press drive according to claim 12, wherein in the flow path of pressure medium between the adjustable hydraulic machine (120) and the adjustable hydraulic motor (122) a consumer valve (128) is provided to take up medium. pressure for other consumers and / or a fast running accumulator arrangement (110). Press drive according to claim 5 or a claim referring thereto, with control equipment for switching the accumulator switching valve (38) and / or the non-return valve (14) which can be unlocked when a pressure threshold is exceeded in the pressure chamber (12) of the retaining cylinder (6).