EP3421155B1 - Hydraulic circuit device for a cold chamber casting machine - Google Patents

Description

The present invention relates to a hydraulic circuit arrangement for a cold chamber die casting machine for the production of metal components, with a battery for providing a hydraulic fluid, with a working cylinder piston chamber having a working cylinder having a first controllable control valve line connection, via which the battery is connected to the working cylinder piston chamber, with a pressure booster piston space and a Druckübersetzerstangenraum having pressure intensifier for increasing the pressure in the working cylinder piston chamber, and with a line connection, via which the battery with the pressure booster piston chamber is connected or connected. The invention also relates to a method for operating a cold chamber die casting machine, wherein in a first phase filling of a mold cavity upstream Füllbuchse with liquid metal by means of a slow advancing movement of a working cylinder piston rod of a working cylinder, wherein in a second phase, the liquid metal by means of a rapid feed motion the working cylinder piston rod is injected into the mold cavity, and wherein in a third phase the pressure on the working cylinder piston rod is increased by means of a pressure booster during the cooling of the injected metal, the supply of a working cylinder piston chamber of the working cylinder through a first control valve with a hydraulic fluid by means of a battery takes place and also the supply of a pressure booster piston chamber of the pressure booster with the hydraulic fluid by means of the battery.

Such a cold chamber die casting machine is used in particular for the production of structural parts of motor vehicles, with ever larger structural parts to be produced with ever more filigree shapes in a cold chamber die casting machine. It is therefore desirable that high pressures may already be present on the working cylinder piston chamber, especially in the second phase.

A circuit arrangement and a method with the features mentioned are out EP 2 295 171 B1 known. In the previously known circuit arrangements for a cold chamber die casting machine, a check valve in the line connection is always arranged, which connects the working cylinder piston chamber with the pressure booster piston chamber. This check valve ensures after the shooting of the liquid metal in the second phase that a recovery of the hydraulic fluid in the third phase from the working cylinder piston chamber is prevented out, so that an increase in pressure in the working cylinder piston chamber by means of the pressure booster is possible. However, this check valve reduces the flow area during the supply of the working cylinder piston chamber in the first and second phase and thus the achievable in the working cylinder piston chamber pressure. The check valve must also be regularly maintained and replaced if necessary.

EP 2 365 888 B1 suggests, therefore, that the pressure booster itself has a valve seat, which forms with the pressure booster piston a check valve or check valve, which prevents the feeding back from the working cylinder piston chamber in the third phase. For the training of this function, it is necessary that the valve seat movable in the Pressure booster is mounted so that the manufacturing cost of the pressure booster and its maintenance costs are increased.

Out JP 2010 264 468 A and US 2016/279701 A1 is in each case a cold chamber die casting machine with the features of the preamble of claim 1, in which in each case a check valve is arranged in the line connection between the battery and the working cylinder piston chamber.

The object of the present invention is therefore to overcome the drawbacks described with reference to the prior art, and more particularly to provide a hydraulic circuit arrangement for a cold chamber die casting machine and a method for operating a cold chamber die casting machine, in which a higher force on the working cylinder piston rod in the first and second phase achievable, while reducing the manufacturing and maintenance costs.

The object is achieved by a hydraulic circuit arrangement and a method having the features of the respective independent claim. Advantageous developments of the circuit arrangement and the method are specified in the dependent claims and in the description, wherein individual features of the advantageous developments in a technically meaningful way can be combined with each other, where described with respect to the features and advantages transferable to the circuit arrangement and applicable, as well as vice versa.

The object is in particular achieved by a hydraulic circuit arrangement with the features mentioned, in which the first control valve has a blocking position and a passage position and in which there are no internals for closing the line connection in the line connection between the battery and the working cylinder piston chamber behind the first control valve in which a return of the fluid from the working cylinder piston chamber can be prevented by blocking the first control valve, and in which the battery is connected to the pressure booster piston chamber by means of a line connection parallel to the first control valve or is connectable, via which the pressure booster piston space can be acted upon during the pressure increase.

The object is also achieved by a method having the features mentioned in the introduction, in which the fluid in the first and second phases is fed from the accumulator to the working cylinder piston chamber through the first control valve and thereafter by no further fittings for closing the corresponding line connection, wherein in the third phase, a recovery from the working cylinder piston chamber is prevented by blocking the first control valve and in which the pressure booster piston chamber is acted upon in the third phase by a parallel to the first control valve line connection from the battery.

The invention is therefore beyond the prejudice that the working cylinder piston chamber and the pressure booster piston chamber must be connected via an at least partially common line connection to the battery and that timely prevention of recovery from the working cylinder piston chamber in the transition from the second to the third phase only by means of a passive check valve is possible.

In contrast, the return of the hydraulic fluid from the working cylinder piston space during the third phase according to the invention is prevented by the first control valve, which also controls the advancing movement of the working cylinder piston rod in the first and second phases. By contrast, the admission of the pressure booster piston chamber with the hydraulic fluid during the third phase takes place by means of a line parallel to the first control valve. By omitting a check valve or a device which takes over the function of the check valve in the line connection between the first control valve and the working cylinder piston chamber can already during the first and / or the second phase, a higher Pressure in the pressure cylinder piston chamber are brought to bear, so that higher forces can act on the working cylinder piston, whereby larger and / or filigree components produced and / or a faster shot time can be achieved in the second phase. Since these advantages are achieved without further mechanical components, the manufacturing costs and maintenance of such a cold chamber die casting machine are reduced. Thus, the life of the cold chamber die casting machine is reduced.

The externally controllable first control valve has in addition to its acting in both directions blocking position on a variable passage position, so that the feed rate of the working cylinder piston rod in the first and second phase by means of the degree of opening of the passage position is adjustable. In particular, the first control valve is arranged to be switchable from a passage position to the full blocking position within less than 50 ms (milliseconds), preferably less than 20 ms or even less than 10 ms.

The hydraulic circuit arrangement is set up in particular for a pressure of at least 150 bar. In particular, a pressure of at least 150 bar in the battery can be generated, which can be brought via the controllable control valves for acting on the cylinder, wherein the line connections of the circuit arrangement are designed for corresponding pressures.

Preferably, the parallel to the first control valve line connection between the battery and the pressure booster piston chamber is designed without valves. However, it can be provided that in this parallel to the first control valve line connection, a control valve or other valve is arranged.

As a rule, the third phase for increasing the pressure in the working cylinder piston chamber is initiated by opening a line connection connected to the pressure booster rod chamber by means of a corresponding valve so that fluid present here can flow out. Preferably, this valve is designed as a second controllable control valve, which has a blocking position and a passage position. In the blocking position acting in both directions, therefore, the pressure booster rod space is separated from the rest of the circuit arrangement. The second control valve is in particular designed such that in the passage position of the flow cross section is variable by the second control valve. In particular, the second control valve is set up so that the changeover from the blocking position into the passage position can take place within less than 50 ms, preferably less than 20 ms or even less than 10 ms.

In this context, it is particularly preferred that only the second controllable control valve is to be actuated by the pressure booster to increase the pressure in the working cylinder piston chamber. In this case, therefore, no internals in the line connection between the battery and pressure booster piston chamber are present and the third phase is initiated solely by opening the second control valve, while the first control valve is closed.

It is particularly preferred that the first control valve and the second control valve are arranged so that during a pressure increase in the working cylinder piston chamber by the pressure booster the first control valve completely blocks its line connection and the second control valve makes its line connection at least partially permeable. The first and the second control valve are configured, for example via a higher-level control so that both control valves are switched synchronously. So while the second control valve in the transition from the second phase to the third Phase is opened, the first control valve is simultaneously brought into its blocking position.

In the third phase, therefore, the second control valve is switched at least partially permeable, wherein in particular the first control valve and the second control valve are synchronously and preferably switched simultaneously.

After the end of the third phase of the working cylinder piston can be moved back to its original position, as in the aforementioned EP 2 295 171 A1 is described. To return the pressure booster piston after the end of the third phase can be provided that in the line connection from the battery to Druckübersetzerkolbenraum a third control valve is arranged, which is open at least during the third phase and which is closed after the end of the third phase when returning, and in a leading from the pressure booster piston chamber to a tank line connection a fourth control valve is arranged, which is closed in the first three phases and open to return the pressure booster piston. The return of the pressure booster piston is then in particular the fact that the battery or a pump is connected to the pressure booster rod space.

The invention and the technical environment are explained below by way of example with reference to FIG.

The figure shows a schematic hydraulic circuit arrangement for a cold chamber die casting machine. The cold chamber die casting machine includes a die 50 having a mold cavity 51 therein to be filled with the hot liquid metal. The mold cavity 51 is preceded by a stuffing box 52. For introducing the liquid metal in the Füllbüchse 52 and the mold cavity 51 is a working cylinder 20 provided. The working cylinder 20 comprises a working cylinder piston 24 with a one-sided working piston rod 23, wherein the working cylinder piston rod 23 is arranged for retraction into the Füllbüchse 52 to push out the filled into the Füllbüchse 52 metal in the mold cavity 51. The working cylinder piston 24 divides the working cylinder 20 into a working cylinder piston chamber 21 and into a working cylinder rod space 22. In view of a required during die casting increase in the working cylinder piston chamber 21 pressure is the working cylinder 20 associated with a pressure booster 30 having a pressure booster piston 34 with a one-sided pressure booster piston rod 33rd includes, wherein the pressure booster piston rod 33 is arranged for retraction into the working cylinder piston chamber 21. The pressure booster piston 34 divides the pressure intensifier interior into a pressure booster piston chamber 31 and a pressure booster rod chamber 32.

For pressurizing working cylinder piston chamber 21 and pressure booster piston chamber 31, a battery 10 is provided. The battery 10 can be filled by a first pump 71, wherein in the line between the first pump 71 and the battery 10, a first check valve 61 is turned on to allow the filling of the battery 10 by the first pump 71, but in the opposite direction to prevent a backflow of the fluid to the battery 10 in the direction of the first pump 71.

For feeding or acting on the working cylinder piston chamber 21 performs a battery working cylinder piston chamber line connection 11 from the battery 10 to the working cylinder piston chamber 21. In the battery working cylinder piston chamber line connection 11, a first controllable control valve 41 is arranged. The first controllable control valve 41 has a blocking position and a variable passage position. In the battery working cylinder piston space line connection 11 is behind the first control valve 41 no further device for obstructing the line.

For supplying or pressurizing the pressure booster piston chamber 31 with the hydraulic fluid, a rechargeable battery pressure booster piston chamber line connection 12 is provided, which connects the battery 10 directly to the pressure booster piston chamber 21. The battery 10 is thus connected directly to the pressure booster piston chamber 31 via the battery pressure booster piston chamber connection 12, wherein a third control valve 43 is arranged in the battery pressure booster piston chamber duct connection 12.

To the pressure booster rod space 32, a pressure booster rod space line connection 13 is connected, which leads to a second controllable control valve 42 and a pressure control valve 48 connected downstream of this. From the pressure control valve 48 leads a line to the battery 10. The pressure control valve 48 also has a connection to a tank 80, so that the displaced from the pressure booster chamber 32 fluid can be discharged to the tank 80.

For deriving hydraulic fluid from the pressure booster piston chamber 31, there is provided a pressure booster piston space load line connection 14, in which a fourth controllable control valve 44 is arranged and which leads to a tank 80.

For deriving hydraulic fluid from the working cylinder rod space 22, a fifth controllable control valve 45 in the form of a multiway valve with a plurality of connections a, b, c is connected to this. A first port a connects the fifth control valve 45 to a tank 80, so that when more responsive Position of the fifth control valve 45 of the pressure cylinder rod space 22 to the tank 80 can be relieved.

A second connection b of the fifth control valve 45 is connected by means of a line with a multiplier 90 as a pressure booster. The multiplier 90 has a multiplier piston 94 with one-sided impacted multiplier piston rod 93, wherein the multiplier piston 94 divides the interior of the multiplier 90 into a multiplier piston chamber 91 and a multiplier rod chamber 92. Of the Multiplikatorstangenraum 92 leads a line to the battery 10, in which a second check valve 62 is turned on with a directed toward the battery 10 towards the direction of passage.

A further connection c of the fifth control valve 45 is connected via a line to the battery 10, wherein in this line a third check valve 63 is turned on with a directed towards the battery 10 passage direction.

After the end of the working cycle, the working cylinder piston chamber 21 must first be relieved of the fluid present therein at a high pressure multiplied by the pressure booster 30, and for this purpose the working cylinder piston chamber 21 can be connected to a tank 80 via a sixth controllable control valve 46.

As far as after completion of a working cycle of the working cylinder 20, the pressure booster 30 and the multiplier 90 are due to their initial position, the first pump 71, the sixth control valve 46 is connected downstream. The outgoing from the sixth control valve 46 lines lead to the working cylinder piston chamber 21 and the working cylinder rod chamber 22. With appropriate circuit of the sixth control valve 46 can thus by applying the cylinder rod space 22 by the first Pump 71 funded fluid of the working cylinder piston 24 are returned to its original position, wherein the displaced from the working cylinder piston chamber 21 fluid via the sixth control valve 46 flows to the tank 80. Similarly, the multiplier 90 is a corresponding seventh control valve 47 is provided with connection to a second pump 72 and a tank 80, wherein the seventh control valve 47 are connected by means of corresponding lines with the Multiplikatorkolbenraum 91 and the Multiplikatorstangenraum 92. In this way, a reset of the multiplier 90 is also given here.

Now, the implementation of the method will be described with reference to the above-described circuit arrangement.

Before starting a working cycle, the battery 10 is filled and charged by the first pump 71, wherein a return flow through the first check valve 61 is prevented. In this phase, the sixth control valve 46 is in its blocking position. Before the start of the duty cycle are also the first control valve 41 and the second control valve 42 in its blocking position.

To initiate the first phase, the first control valve 41 is partially opened so that fluid 10 can flow into the working cylinder piston chamber 21 from the battery. Due to the regulation of the fluid flow by means of the first control valve 41, the speed of the method of the working cylinder piston 24 for filling the filling sleeve 52 can be regulated.

If the filling bushing 52 is filled and if the metal contained therein is now to be injected into the mold cavity 51 of the pressure casting mold 50 in the second phase, another ancestor of the working cylinder piston 24 takes place at high speed. During this fast forward drive of the working cylinder piston 24, the fifth control valve 45 is placed in a position in which the fluid displaced from the working cylinder rod space 22 is supplied to the multiplier 90. Due to the area ratios on the multiplier piston 94 with multiplier piston rod 93, an increase in the pressure for the fluid expelled from the multiplier 90 takes place in the multiplier rod chamber 92, which is conducted via the second check valve 62 to the battery 10, wherein the pressure generated by the pressure increase in the battery 10th given pressure corresponds.

As far as at the end of Einschießvorgangs the second phase, a deceleration of the working cylinder piston 24, during this short period, the first control valve 41 is brought into a low open position, so that the working cylinder piston chamber 21 is acted upon only with a small amount of fluid. At the same time, the fifth control valve 45 is again brought into a position (position c) in which the working cylinder rod space 22 is connected to the battery 10, so that the fluid expelled from the working cylinder rod space 22 is fed back into the battery 10. The build-up in this short phase high system pressure in the working cylinder rod space 22 ensures that the piston movement is reduced delay in a few milliseconds to the desired value, the excess energy is fed back into the battery 10 tip-free in the form of fluid pressure.

At the end of the braking phase of the working cylinder, the first control valve 41 is completely closed and spent in its blocking position, whereby a return of hydraulic fluid from the working cylinder piston chamber 21 is prevented. At the same time the second control valve 42 is fully opened to initiate the third phase, with the third control valve 43 open, so that the pressure booster piston 34 moves in the direction of the working cylinder 20 and increases the pressure in the working cylinder piston chamber 21. The fluid exiting the pressure booster rod chamber 32 is via the second Control valve 42 and the pressure control valve 48 to the tank 80 derived. As far as at the end of the third phase, a relaxation of the pending in the working cylinder piston chamber 21 high pressure must be, the fluid via the sixth control valve 46 and the first check valve 61 is fed to the battery 10, so that the excess energy in the form of fluid also by feeding back into the Battery 10 is usable.

As far as at the end of each working cycle a provision of the participating cylinders has to be made, this is done via a corresponding circuit of the control valves 41 to 47. Thus, the sixth control valve 46 is moved to a position in which by feeding fluid into the working cylinder rod space 22 of the working cylinder piston 24, the fluid displaced from the working cylinder piston space 21 is discharged to the tank 80. The same applies to the provision of the multiplier 90 by means of the associated sixth control valve 46th

To reset the pressure booster piston 34, the third control valve 43 is closed, so that the pressure booster chamber 32 is connected to the battery 10 via the pressure control valve 48 and the second control valve 42, which is open during the return travel. At the same time, the fourth control valve 44 is opened, so that the displaced from the pressure booster piston chamber 31 fluid can be displaced into the tank 80.

LIST OF REFERENCE NUMBERS

10

battery pack

11

Battery power cylinder piston chamber-line connection

12

Battery-pressure intensifier piston chamber-line connection

13

Intensifier bar room-line connection

14

Intensifier piston chamber relief line connection

20

working cylinder

21

Cylinder piston chamber

22

Cylinder rod chamber

23

Working cylinder piston rod

24

Cylinder piston

30

Pressure intensifier

31

Intensifier piston chamber

32

Intensifier rod space

33

Intensifier piston rod

34

Pressure booster piston

41

first controllable control valve

42

second controllable control valve

43

third controllable control valve

44

fourth controllable control valve

45

fifth controllable control valve

46

sixth controllable control valve

47

seventh controllable control valve

48

Pressure control valve

50

die

51

mold cavity

52

shot sleeve

61

first check valve

62

second check valve

63

third check valve

71

first pump

72

second pump

80

tank

90

multiplier

91

Multiplier piston chamber

92

Multiplier rod space

93

Multiplier piston rod

94

multiplier piston

Claims (9)

1. Hydraulic circuit device for a cold chamber casting machine for manufacturing metal components,

   - with an accumulator (10) for supplying a hydraulic fluid,

   - with a working cylinder (20) having a working cylinder piston chamber (21),

   - with a line connection having a first actuatable control valve (41), via which connection the accumulator (10) is connectible to the working cylinder piston chamber (21), wherein no fittings for closing the line connection (11) are present behind the first control valve (41) in the line connection (11) between the accumulator (10) and the working cylinder piston chamber (21), wherein a return flow of the fluid from the working cylinder piston chamber (21) can be stopped by blocking the first control valve (41),

   - with a pressure intensifier (30) including a pressure intensifier piston chamber (31) and a pressure intensifier rod chamber (32) for increasing the pressure in the working cylinder piston chamber (21), wherein the accumulator (10) is connected or connectible to the pressure intensifier piston chamber (31) by means of a line connection (12) parallel to the first control valve (41), via which the pressure intensifier piston chamber (31) can be charged while the pressure is increased,

   characterized in that
   the first control valve (41) has a variable passthrough position additional to a blocking position which is effective in both directions, so that the advance speed of a working cylinder piston rod (23) is adjustable by means of the degree to which the passthrough position is opened.
2. Hydraulic circuit device according to Claim 1, wherein a second actuatable control valve (42) with a blocking position and a passthrough position is disposed in a line connection (13) that is connected to the pressure intensifier rod chamber (32).
3. Hydraulic circuit device according to Claim 1 or 2, wherein a second actuatable control valve (42) disposed in a line connection (13) that is connected to the pressure intensifier rod chamber (32) is operable by the pressure intensifier (30) to increase pressure in the working cylinder piston chamber (21).
4. Hydraulic circuit device according to any one of the preceding claims, wherein the first control valve (41) and a second actuatable control valve (42) disposed in a line connection (13) that is connected to the pressure intensifier rod chamber (32) are configured in such a way that during an increase of pressure in the working cylinder piston chamber (21) by the pressure intensifier (30) the first control valve (41) completely blocks its line connection (11) and the second control valve (42) switches its line connection (13) to allow at least partial passthrough.
5. Hydraulic circuit device according to any one of the preceding claims, wherein a third control valve (43) is disposed in the line connection (12) from the accumulator (10) to the pressure intensifier piston chamber (31) and a fourth control valve (44) is disposed in the line connection (14) which leads from the pressure intensifier piston chamber (31) to a tank (80).
6. Method for operating a cold chamber casting machine,

   - in which in a first phase a shot sleeve (52) positioned upstream of a die cavity (51) is filled with molten metal by means of a slow advancing movement of a working cylinder piston rod (23) of a working cylinder (20),

   - in which in a second phase the molten metal is injected into the die cavity (51) by means of a fast advancing movement of the working cylinder piston rod (23), and

   - in which in a third phase the pressure on the working cylinder piston rod (23) is increased by means of a pressure intensifier (30) while cooling of the injected metal, wherein

   the supply of a hydraulic fluid to a working cylinder piston chamber (21) of the working cylinder (20) through a first control valve (41) is assured by means of an accumulator (10), and the supply of the hydraulic fluid to a pressure intensifier piston chamber (31) of the pressure intensifier (30) is also assured by means of the accumulator (10), wherein

   - in the first and second phases the fluid is supplied to the working cylinder piston chamber (21) by the accumulator (10) through the first control valve (41), which has a variable passthrough position additional to a blocking position effective in both directions, and then through no further fittings for closing the corresponding line connection (11), wherein the advancing speed of the working cylinder piston rod (23) in the first and second phases can be varied by adjusting the degree of opening of the passthrough position, and

   - in the third phase a return flow of the fluid from the working cylinder piston chamber (21) is stopped by blocking of the first control valve (41), and that

   - in the third phase the pressure intensifier piston chamber (31) is charged from the accumulator (10) through a line connection (12) parallel to the first control valve (41).
7. Method according to Claim 6, wherein in the third phase a second control valve (42) which is coupled with a pressure intensifier rod chamber (32) of the pressure intensifier (30) is switched to allow at least partial passthrough.
8. Method according to Claim 7, wherein the first control valve (41) and the second control valve (42) are synchronized.
9. Method according to any one of Claims 6 to 8, wherein when the pressure intensifier piston (34) is retracted a third control valve (43) disposed in the line (12) leading from the accumulator (10) to the pressure intensifier piston chamber (31) is closed and a fourth control valve (44) disposed in a line connection (14) leading from the pressure intensifier piston chamber (31) to a tank (80) is opened.

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