EP2448720B1 - Hydraulic pressing device - Google Patents

Description

The invention relates to a hydraulic pressing device with a fixed part and a moving part, wherein the moving part is moved by a hydraulic piston relative to the fixed part and by means of a return spring in an initial position zurückbewegbar, wherein further the return movement in response to a predetermined pressing pressure can be triggered by addressing a Return valve, wherein, in addition, a control valve is provided which, in addition to the return valve in the open state, a hydraulic fluid discharge free and, based on a state when conveying hydraulic fluid, a hydraulic fluid inflow and outflow side has

Such pressing devices are known in many embodiments WO 99/19947 to refer. In addition, also on the WO 98/24570 , relating to an application as a punching device, the WO 02/062504 , concerning an application as expansion tool and the WO 02/00368 , concerning an application as a riveting tool

Such a pressing device is also for example from the DE 20 2004 000 215 U1 The control valve arranged in a hydraulic line leading from the hydraulic fluid pump to the hydraulic piston leading hydraulic cylinder is penetrated by the hydraulic fluid delivered by the pump according to a design as a check valve from the inflow side to the outflow side. When the hydraulic fluid pump is switched off, the fluid pressure acting on the downstream side, together with a biasing spring acting in the same direction, causes the control valve to move to the open position, thus releasing the hydraulic fluid discharge associated with the downstream side. In addition, since the control valve does not open at higher system pressure, there is still no opening of the control valve at the beginning of the hydraulic fluid return when the return valve has opened after the pressing operation has been completed.

Based on the above-described prior art, the invention is concerned with the task of making such a hydraulic pressing device with regard to the response of the control valve advantageous.

A solution to the problem is given by the subject matter of claim 1, wherein it is pointed out that the control valve is acted upon when the return valve is open by the pressure of the returning hydraulic fluid on the inlet and outlet side, wherein the pressure on the upstream side is lower due to throttling. When the return valve is open, the control valve is exposed to the pressure, if different, of the hydraulic fluid in the return region. The pressure difference resulting from the restriction acts in the opening direction of the control valve and thus in any case promotes or promotes a rapid opening. This effect can be additionally supported by a spring bias of the control valve in the open position. On the other hand, however, in preferred embodiments of the subject invention, this is not the above design criterion for an optionally selected preload. After opening the return valve results in almost immediately, possibly even in conjunction with the opening of the return valve, an opening of the control valve and thus a dual drainage possibility for the hydraulic fluid. As a result, it can be seen that a desired fast return of the hydraulic piston can be achieved. On the other hand, there are also applications in which the setting is made so that only a very small amount of the hydraulic fluid via the return valve runs.

It is further preferred that a hydraulic pump is provided, from which pump a (first) hydraulic fluid flow path leads to the control valve and a further (second) hydraulic fluid flow path leads directly to the return valve. The from the hydraulic pump to the control valve and preferably also to a return piston receiving Hydraulic cylinder leading hydraulic fluid supply line is also given directly from the hydraulic fluid pump to the control valve. The said hydraulic fluid flow paths can also partially coincide. It is essential that due to the direct connection, the hydraulic fluid flows through the supply line to the control valve or to the return valve, without first, about to flow with respect to the return valve, via the control valve. As a result, with respect to the two valves, a parallel circuit is provided starting from the hydraulic fluid pump. Hydraulic fluid inlet (from the pump) and hydraulic fluid drain through the (open) return valve are located hydraulically on the same side of the control valve. The connection to the cylinder chamber (moving part) is located hydraulically on the other side of the control valve (or in the bypass for this purpose). Seen from the moving part, the return valve may be arranged hydraulically after the control valve or, at least in addition, in parallel with the control valve. Essential is the possible compact arrangement of said valves and the hydraulic lines.

The biasing the control valve in the open position spring can be formed with a relatively low spring force. Thus, no opening of the control valve is given even when stopping the pump in the course of the initiation of the compression process or in an already more advanced compression. Rather, the control valve moves only in its open position, if in addition, according to open return valve, a negative pressure of the control valve or a pressurization pressure difference sets Usually, in a hydraulic hand press, which is preferred here, the compression by a manual actuation of the pump, which is preferably driven by an electric motor achieved. If the depression of a corresponding switch is interrupted, the pump also stops running. Press jaws of a pressing device remain in a certain position. In the embodiment described here, by resuming the operation of the pressing process be continued without further ado. There is no running back of the hydraulic piston. Not even at a beginning of a Verpressvorganges still very low system pressure or (over) pressure level in the hydraulic cylinder.

The term "control valve" is chosen for clear conceptual separation. You can also call this valve as another return valve, for example.

It is further preferred initially that the control valve is designed as a seat valve. By driving against a seat stop, the valve closes the hydraulic fluid drain. The closed by the seat valve opening extends (relative to an axis of the opening) in the direction of displacement of the control valve. There is no Abschieberung, but a closure of a drain opening whose opening area in coverage of the control valve, based on a projection in the direction of movement of the control valve is located

Associated therewith, though not necessarily connected, is the fact that the closed control valve is acted upon by a differential force formed by the pressure in the hydraulic medium reservoir and the pressure in the hydraulic fluid supply line. Since in almost all operating conditions, the pressure in the hydraulic fluid supply line is higher than the pressure in the hydraulic fluid reservoir, this results in a locking force of the control valve when it is in the closed position. Although initially a higher pressure is required to move the control valve in the closed position, then, when it is in the closed position, also a lower pressure in the hydraulic medium supply line, as long as this pressure is still sufficiently higher than that Pressure in the hydraulic fluid reservoir. The pressure in the hydraulic fluid reservoir can correspond to the ambient pressure or even be lower than the ambient pressure, so be a negative pressure. The latter especially if the pump with high flow rate works. The higher pressure which serves to displace the control valve into the closed position arises due to the pressure loss of the flowing hydraulic fluid via the control valve, as seen from the inflow side to the outflow side. It is, as it were, a dynamic pressure due to the movement of the hydraulic fluid or the pressure difference resulting from the control valve. The control valve responds to the direction of flow of the hydraulic fluid.

The pressure in the hydraulic fluid supply line accordingly increases upon initiation of a squeeze operation from ambient pressure (or slightly above) to the squeeze trigger pressure. Such a trigger pressure can for example be between 300 and 700 bar. After pressing, when the return valve has opened, the pressure in the hydraulic fluid supply line, which then depending on the configuration, as described below, hydraulic fluid runs back into the storage room, for example, 10 and 0.5 bar (pressure) , In this case, all intermediate values, in particular in steps of 0.1 bar, are included in the disclosure.

The hydraulic fluid pump delivers via a delivery line into a first branch line leading to the control valve and a second branch line leading to the return valve. When a conventional grouting operation is triggered, the return valve is closed or is closed, for example, by releasing an opening detent in the course of this triggering. The hydraulic fluid is therefore only in this branch line, but does not flow. However, it flows through the control valve and the hydraulic fluid supply line then into the cylinder chamber. In addition, a bypass can be provided directly in the cylinder chamber. The promotion to the return valve is carried out according to line or not only via the control valve, but, if appropriate, in parallel thereto. The return valve is related to the hydraulic fluid delivery hydraulically connected in parallel to the control valve.

Further, it is preferably also provided in this context that when the return valve is opened via the return valve, the hydraulic fluid flowing out initially, preferably as a whole, flows via the control valve. In this case, the return valve is hydraulically connected downstream of the control valve at draining hydraulic fluid. But it can also be provided that it flows only partially through the control valve. On the other hand, it can flow through a line leading directly from the cylinder to the return valve, this line furthermore preferably having a throttle point. It may also flow in total via said separate line from the cylinder space to the return valve. Even in the latter case, however, it is provided that this leading to the return valve line is in line connection with the control valve, and to the upstream side of the control valve. Also in this structural design, therefore, in the case of the return of hydraulic fluid, the respective pressurization is given on the upstream side of the control valve.

The control valve may be biased by a spring in its open position. This bias is preferably chosen to be lower in this case than corresponds to a force acting on the control valve by a spring action of the return piston force. The caused by the spring action of the return piston in the case of the return in the hydraulic medium supply line pressure, which, as stated, for example, between 0.5 and 5 bar may be, corresponding to the hydraulically effective surface of the control valve to a force acting thereon. Regardless of the possibly additionally supporting acting lower pressure or even negative pressure in the hydraulic fluid reservoir, the said force exerted by the spring action of the return piston force is greater than that corresponding to the force acting on the control valve in the opening direction spring force. A realistic one Size for the force of this acting on the control valve in the opening direction spring is for example between 0.1 and 1 Newton, more preferably between 0.2 and 0.4 Newton, in which range also all intermediate values, in particular in 1/10 Newton Steps are included.

As an alternative to the configuration described above, in the case of opening the return valve, hydraulic fluid at least partially flows via the control valve to the return valve, it can also be provided that the control valve in its open position at the same time the hydraulic fluid supply line, via which otherwise hydraulic fluid to the return valve can flow, blocked. Whereby this blocking may preferably also be given in the sense of a seat valve. The outflow can then be given via an example provided direct line connection from the hydraulic cylinder to the return valve, as already mentioned. However, the outflow via the return valve can thereby be completely interrupted. The return valve goes in this case, because of the associated pressure drop, immediately in its closed position.

The return valve is set to the highest pressure, the pressure to be achieved. The control valve allows due to the (further) pressure drop resulting from its opening an automatic control of the return valve in the closed position, with simultaneous opening of a (further) discharge path for the hydraulic fluid. This can be achieved in the desired manner in the course of carrying out a pressing process first, take each intermediate position and then continue the pressing process. After carrying out the pressing operation can be achieved by simply re-actuation of the pump stopping the moving part, ie usually the return piston, and made from this position from the next pressing.

The control valve consists in detail of a valve closure body, which cooperates with a - fixed to the housing - valve seat. In this regard, it is preferably provided that the valve closure body passes through a compensating part which also follows the movement of the valve closure body. The compensation part thus moves with the valve closure body from the closed position to the open position and vice versa. The compensating part is designed such that the valve closure body can move transversely to its direction of movement when moving from the closed position to the open position or vice versa. For this purpose, the valve closure body is also preferably received in the hydraulic medium supply line with a corresponding play. This mobility of the valve closure body ensures that even with not exactly aligned alignment of the valve seat with the valve closure body results in a reliable closure of the control valve. The valve closure body accordingly has sufficient movement possibility with respect to possible manufacturing tolerances.

The compensating part may be formed, for example, in the form of a washer. Also, the compensation part, for example, specifically the washer, is preferably not sealingly fitted in the more preferably at least in this area cylindrically shaped hydraulic fluid supply line. Rather, here also a suitable, albeit very small, radial gap can remain, which allows a certain flow of hydraulic fluid. In any case, such a gap in the idle state allows the pressure equalization via the compensating part. A realistic size for such a gap is about 1/100 to 2/100 mm. In contrast, the possibility of movement of the valve closure part transverse to its direction of movement with respect to an opening or closing operation can be 2/100 to 10/100 or more hundredths of a millimeter, for example up to a 1/2 mm.

Fig. 1

eine, teilweise geschnittene, Darstellung eines vorderen Teils eines Pressgerätes;

Fig. 2

eine Vergrößerung des Bereiches 2-2 in Fig.1, bei geschlossenem Steuer- und Rücklaufventil;

Fig. 3

eine Darstellung gemäß Fig. 2, bei geöffnetem Steuerventil;

Fig. 4

eine Darstellung gemäß Fig. 2 mit zusätzlicher Drosselöffnung;

Fig. 5

eine Darstellung gemäß Fig. 4, mit abgewandelter Drosselöffnung; und

Fig. 6

eine vergrößerte Darstellung des Steuerventils bezogen auf den Bereich VI - VI in Fig. 3, mit Ausgleichsteil.

The invention will be further explained with reference to the accompanying drawing, which, however, shows only exemplary embodiments

Fig. 1

a partially sectioned, representation of a front part of a pressing device;

Fig. 2

an enlargement of the range 2-2 in Fig.1 , with closed control and return valve;

Fig. 3

a representation according to Fig. 2 with the control valve open;

Fig. 4

a representation according to Fig. 2 with additional throttle opening;

Fig. 5

a representation according to Fig. 4 , with modified throttle opening; and

Fig. 6

an enlarged view of the control valve relative to the area VI - VI in Fig. 3 , with compensation part.

Shown and described, first with reference to Fig. 1 The moving part 3 is moved by means of a hydraulic piston 4 relative to the fixed part 2, which can also be considered as the entire housing, the hydraulic piston 4 is moved back by means of a return spring 5 in its initial position and biased in the non-use state to the starting position thereby. The return movement of the hydraulic piston 4 can be triggered by the response of a return valve 6 at the end of a pressing operation. This return valve 6 is formed in the embodiment and operates as described in the EP 0 944 937 B1 The disclosure content of this document is hereby incorporated in full in the disclosure with regard to the design of this return valve and the corresponding mode of operation Application, also to include one or more of the features known there in claims of this application.

Furthermore, a control valve 7 is provided which influences the closure characteristic of the return valve 6. Because preferably, the return valve 6 is no longer open until complete return of the hydraulic piston 4. According to the control valve 7 results in the opening state of this control valve 7 such a strong pressure drop before the return valve 6, that it prematurely in this sense, before the hydraulic piston 4 reaches its end-return position closes. A further return movement of the hydraulic piston 4 then takes place only by outflow of hydraulic fluid via the discharge opening 8 released by the control valve 7 in the opening state into the hydraulic fluid reservoir 9.

In detail, the control valve 7 has an inflow side 10 and an outflow side 11. The inflow side 10 refers to the fact that the control valve 7 is acted upon by the hydraulic medium on this side during the delivery of hydraulic fluid by means of the hydraulic fluid pump 12. Via the outflow side 11, the hydraulic fluid flows through the hydraulic medium line 13 into the hydraulic cylinder 14, in which the hydraulic piston 4 is accommodated. The hydraulic pump 12 may be a piston pump as shown. But it may also be, for example, a screw pump. The latter has the advantage that it is pumped with a continuous pressure. When pumping hydraulic fluid through the open control valve 7, which is associated with this, but also practically immediately displaced into the closed position, resulting throttling effect, a pressure drop of, for example, 1 bar, which causes said shift to the closed position

The way of returning hydraulic fluid, including in detail Fig. 2 Reference is made, is given at the beginning, when opening the return valve 6, via the control valve 7, according to a circumferentially left Passage gap 15 hydraulic fluid can flow past. Since this passage gap 15 is relatively small, this results in apparent throttling, which leads to a pressure drop across the control valve 7. On the inflow side 10, which is actually a downstream side in this state, there is correspondingly then a lower pressure than on the downstream side 11. In addition, a certain back pressure on the outflow side may additionally result. By this pressure difference and supported by the control valve 7 biasing in the open position compression spring 16, the control valve 7 is very rapidly in the open position according to Fig. 3 relocated.

In a conventional design, but it actually does not need the compression spring 16 to move the control valve 7 in the open position. Due to the self-adjusting flow through the discharge opening 8, however, a suction effect on the open control valve 7 may result, which is counteracted by means of the compression spring 16.

The open position according to Fig. 3 on the one hand can be provided so that a dense or nearly dense valve seat 17 results An opening seat portion 18 of the control valve 7 sealingly cooperates with the housing 36, which has a valve seat with ausformende constriction in this area. As a result, in the formation of the control valve as a shuttle valve, wherein the control valve in one position (closed position) closes the drain opening 8 and in the other position (with respect to the final position 8: open position) closes the flow to the return valve 6, results in a closing the return valve 6 also in the event that this should have such a large hysteresis that it would otherwise remain in the open position during the entire return of the hydraulic piston. Thus, even after opening the return valve is given enough time to turn off the hydraulic pump so that the control valve is not immediately closed again when the return valve closes and the pump would still promote. The design can also be provided so that in the opening state of the control valve 7 according to Fig. 3 still a flow of hydraulic fluid to the return valve 6 remains. With increasing retraction of the hydraulic piston 4, the spring 5 relaxes and the pressure exerted on the hydraulic fluid pressure is reduced. Accordingly, the return valve 6 can then be moved into a closed position, if a required critical pressure, which is required to maintain the opening state of the return valve 6, is exceeded. Here, too, the closed position of the return valve 6 is reached before the hydraulic piston 4 is completely moved back to its final position. However, the setting can also be made so that, approximately to achieve the fastest possible retraction of the hydraulic piston, the control valve 7, as well as Return valve 6, remain in the open position until reaching the end position. In the illustrated embodiment, the setting is provided so that the return valve 6 immediately moves into its closed position when the control valve 7 opens.

The flow of the hydraulic fluid then takes place only through the drain opening 8, which is formed in the valve seat of the control valve 7

In addition to the path of the hydraulic means when triggering a pressing operation via the control valve 7 can be provided for this purpose in the bypass conveyor 19, see Fig. 4 . 5 be trained. This is preferably designed as a throttle point. According to Fig. 5 it may also be closed by a check valve 20, so that only when pumping hydraulic fluid through the pump 12 hydraulic fluid flows through the delivery path 19.

In the embodiment according to Fig. 4 Even after the return valve 6 has been triggered, hydraulic fluid flows through the delivery path 19 into the space 21 and from there, with the return valve 6 open, via the return valve 6 into the hydraulic fluid reservoir 9.

The embodiment described here is in many ways of particular advantage.

If, after initiation of a pressing operation by appropriate switch operation, the running of the pump 12, which is driven for example via an electric motor, is triggered, the control valve 7 is immediately moved to the closed position. The return spring 16, which acts on the control valve 7 in the open position, in this case is designed so that even after a successful initiation of the pressing operation interrupting the pump, such as by the switch is no longer pressed, acting on the control valve 7 closing pressure is sufficient to keep the control valve 7 in the closed position. Then there is no return of the hydraulic piston 4. By pressing the release switch again then the pressing process can be continued, at the same position of the hydraulic piston 4, this has taken on interruption of the pumping operation. However, if a return of the hydraulic piston 4 is desired, this can be done in addition via the manual switch 21, which acts on the return valve 6, see Fig. 4 , to be triggered.

On the other hand, the design of the control valve 7 is made so that the pressure drop described in the case that the return valve 6 triggers, each shift the control valve 7 in the open position. Due to the bias by means of the spring 16, the control valve then remains in this open position.

During a return of the hydraulic piston 4, which then takes place, the pump 12 can be actuated again at any time by a switch actuation. Immediately, the control valve 7 moves in the closed position, whereby the hydraulic piston 4 is stopped at the then reached position in the hydraulic cylinder 14. Without a complete retraction is required, then from this position, the next compression can be performed.

The control valve 7 is seen to be formed in further detail with a front cone-shaped seating area 22, which merges via a cylinder portion 23 into an enlarged flange area 24. At the end of this flange region 24, a throttling region 25 adjoins. When the control valve 7 is displaced in the mentioned manner in the open position, this is a very fast, practically instantaneous process. Due to the fact that the throttle region 25 dips into the passage opening 26, which is only a little larger, this results in a desired deceleration and a gentle abutment of the region 24 on the wall of the housing.

Following this, an elongate shaft 27 is formed, which extends with an extension 29 into an inlet bore 28 of the return valve 6 The inlet bore 28 continues in a perpendicular thereto extending continuation 30, in which the return valve 6 is arranged The shaft 27 passes through the room 21, which is first reached by funded by the pump 12 hydraulic fluid. This space 21 is clearly branched into an inlet to the control valve 7 and an inlet to the return valve 6. In addition, in the bypass line 19, if this is provided.

Associated with the drain opening 8, a baffle 31 is provided on the supply chamber side. Even with a small diameter of the drain opening 8, a thin, strong hydraulic fluid jet caused thereby can not lead to damage of the opposite wall 32 of the storage space 9. Especially since the wall 32 is preferably formed by a resilient rubber material. The baffle 31 is formed in detail by a T-tube, wherein a portion of the T-tube is formed as Einschraubabschnitt, the end forms the seat for the control valve 7 and the other portion of the T-tube forms said baffle.

In reference to Fig. 6 It can be seen that the valve body of the control valve 7, which has the seating area 22, the cylinder portion 23 and the flange area 24, passes through a compensation part 33. The compensation part 33 is designed as an annular body, with an inner diameter Di, which is smaller than an outer diameter Da of the flange portion 24. The compensating part 33 is seat area side of the flange portion 24, so in the embodiment of the cylinder portion 23, of the valve closure body interspersed by the inner diameter Di of the compensating part 33 leaves a gap s with respect to said cylinder portion 23. This gap s allows the valve closure body to move transversely to its longitudinal extent. This automatically results in a certain transverse displacement when, for example, the counter-valve seat forming bore 34 of the here formed by the T-tube valve seat portion 34 should not be aligned with a longitudinal center axis of the valve body.

As below also about Fig. 2 and from the above description, is from the hydraulic fluid pump 12, a flow path through the space 21 and the line branching from this 35 directly to the return valve 6. Hydraulically speaking, so in terms of the at least theoretical way that the hydraulic fluid at Flowing back, the hydraulic fluid supply, in the form of the hydraulic fluid pump 12 and the immediately subsequent conduction path, and the return valve 6 are arranged hydraulically on the same side, namely the upstream side of the control valve 7.

LIST OF REFERENCE NUMBERS

1

Hydraulic press machine

2

hard part

3

moving part

4

hydraulic pistons

5

Return spring, spring

6

Return valve

7

control valve

8th

Outflow opening / hydraulic fluid drain

9

(Hydraulikmittel-) pantry

10

inflow

11

outflow

12

Hydraulic fluid pump

13

Hydraulic medium line

14

hydraulic cylinders

15

Passage gap

16

Spring / return spring

17

valve seat

18

Opening seat portion

19

Conveying / bypass line

20

check valve

21

Room / manual switch

22

sitting area

23

cylinder section

24

flange

25

throttle region

26

Through opening

27

shaft

28

inlet bore

29

extension

30

continuation

31

baffle wall

32

Wall of the storage room 9

33

compensating part

34

Bore / seat part

35

Bore section / line section

36

housing

Claims (10)

1. Hydraulic press unit (1) having a fixed part (2) and a movable part (3), the movable part being moved relative to the fixed part (2) by means of a hydraulic piston (4) and being movable back into a starting position by means of a return spring (5), and in addition the return movement being actuatable as a function of a predetermined applied pressure by activation of a return valve (6), and furthermore a control valve (7) being provided which, in addition to the return valve (6), opens a hydraulic-medium outlet (8) and, with reference to a state when hydraulic medium is flowing, has a hydraulic-medium inflow side and a hydraulic-medium outflow side, characterized in that when the return valve (6) opens, the control valve (7) is acted on by the pressure of the returning hydraulic medium on the inflow and outflow sides, the pressure being lower on the inflow side due to throttling.
2. Hydraulic press unit according to Claim 1, characterized in that a hydraulic-medium pump (12) being provided, from which pump a hydraulic-medium flow path leads to the control valve, and that a hydraulic-medium flow path leads from the hydraulic-medium pump directly to the return valve (6).
3. Press unit according to one of the preceding claims, characterized in that the control valve (7) is formed as a seat valve.
4. Press unit according to one of the preceding claims, characterized in that the control valve (7) is situated in a feed line leading to a hydraulic cylinder (14) which accommodates the hydraulic piston (4).
5. Press unit according to one of the preceding claims, characterized in that the closed control valve is acted on by a differential force that is formed by the pressure in the hydraulic-medium storage space and the pressure in the hydraulic-medium feed line.
6. Press unit according to one of the preceding claims, characterized in that the hydraulic-medium feed line leading from the pump to the cylinder has a direct connection to the return valve and to the control valve.
7. Press unit according to one of the preceding claims, characterized in that hydraulic medium flowing back through the return valve first flows through the control valve.
8. Press unit according to one of the preceding claims, characterized in that a biasing force acting on the control valve and urging it into the open position is less than equates to a force acting on the control valve by virtue of a spring action on the return piston.
9. Press unit according to one of the preceding claims, characterized in that the control valve in the open position blocks a return flow of hydraulic medium to the return valve.
10. Press unit according to one of the preceding claims, characterized in that the control valve has a closing body which passes through a compensating part for lining up a movement of the valve closing body.

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