Hydraulic casting unit

Abstract

The invention relates to a casting unit, the casting cylinder of which can be operated regeneratively in the prefill phase by means of a flow regulating valve. By means of this flow regulating valve a boosting unit, for example a pressure intensifier or a high-pressure accumulator, is also switched on in the pressure maintenance phase.

Description

Technical Field

[0001] The invention relates to a hydraulic casting unit. Background Art

[0002] The basic structure of such a casting unit, used in prototype machines such as injection molding machines, die-casting machines, or thixomolding machines, is disclosed, for example, in DE 10 2017 220 832 A1, originating from the present applicant. The casting unit comprises a dual-acting casting cylinder, whose piston defines a bottom chamber on the piston bottom side, and whose piston-rod-side end face defines an annular chamber. In known solutions, the bottom chamber is initially connected to a low-pressure reservoir during the pre-charging and mold filling phases via a 2 / 2-way seat valve, for example, configured as active logic. The annular chamber of the casting cylinder is connected to the bottom chamber via a regulating valve. Thus, the pressure medium displaced from the shrinking annular chamber during the pre-charging phase is supplied to the enlarging bottom chamber via a regulating valve in the regeneration circuit. During the mold filling phase, a pressure medium connection to the tank can be established for injection via a tank-side regulating valve, and the regulating valve is closed between the piston chamber and the annular chamber. During the holding phase, the bottom chamber is then connected to the high-pressure accumulator via another control valve, with the pressure medium connection to the low-pressure accumulator being blocked by active logic. During this holding phase, the aforementioned tank-side control valve maintains an open pressure medium connection between the annular chamber and the tank, thereby compressing the melt in the mold cavity with high pressure and compensating for any material losses.

[0003] The basic structure of the active logic used in this casting unit is known from document DE 10 2005 035 170 B4.

[0004] In a casting unit disclosed in document DE 10 2017 221 500 A1, no regeneration circuit is provided. During the pre-charging and mold filling phases, the bottom chamber is charged with a low-pressure reservoir via active logic and the outlet-side regulating valve is connected, causing the piston of the casting cylinder to move out at a predetermined speed. During the transition from the pre-charging phase to the mold filling phase, this outlet-side valve remains open, causing the piston to accelerate and move out at a higher speed. The pressure medium expelled from the shrinking annular chamber flows through the outlet-side regulating valve to the outlet reservoir and then, when a predetermined pressure is reached in the outlet reservoir, flows out through a check valve or a baffle to the tank. This reduces the maximum volume flow to the tank and the associated turbulence.

[0005] After the pre-charging phase, the pressure intensifier (multiplier cylinder) is accelerated to initiate the pressure holding phase, thereby building up a higher pressure in the bottom chamber. This acceleration is achieved by connecting the annular chamber of the pressure intensifier to a low-pressure reservoir or tank via a regulating valve. Summary of the Invention

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to create a casting unit which enables an optimized casting process with low equipment expenditure.

[0007] This object is achieved by a casting unit according to the invention.

[0008] Advantageous further developments of the invention are described below.

[0009] The hydraulic casting unit according to the present invention, preferably designed for use in an injection molding machine, a die-casting machine, or a thixomolding machine, comprises a casting cylinder designed as a differential cylinder, the piston of which defines a bottom chamber on the bottom side and an annular chamber on the piston rod side. The casting unit also comprises a regulating valve designed to connect the annular chamber to the bottom chamber in the manner of a regeneration circuit during the precharging and / or mold filling phases. The casting unit also comprises an outlet valve for connecting the tank line connected to the annular chamber to the tank during the mold filling and holding pressure phases. Furthermore, according to the present invention, a low-pressure source connectable to the bottom chamber via a shutoff valve arrangement (low-pressure valve) and a hydraulic boost unit designed to assist the extension movement of the casting cylinder during the holding pressure phase are provided. According to the invention, the regulating valve is designed as a multi-way flow regulating valve, hereinafter referred to as a flow regulating valve, having a closed position. The slide of the flow regulating valve is designed to open a pressure medium connection between the bottom chamber and the annular chamber in a first adjustment direction, in the manner of the aforementioned regeneration circuit, and to activate the boost unit in a second adjustment direction. The flow regulating valve preferably also allows pressure medium to be discharged from the bottom chamber during pressure control.

[0010] In this circuit, only two control valves (the aforementioned flow control valve and the flow control valve in the outlet) are required to perform the basic functions (regeneration during the pre-charging phase, the mold filling phase, and the holding pressure phase). This significantly reduces the equipment complexity compared to conventional solutions. The flow control valves that enable regenerative operation of the casting cylinders allow for the use of smaller reservoirs. Due to the low pressure differential across the flow control valves, the regeneration function results in less cavitation and less wear. Furthermore, the casting cylinders can be operated at lower speeds and with greater precision.

[0011] The pressure build-up and pressure reduction during the pressure holding phase are essentially accomplished via the flow control valve and the intensification unit, so that a significant system improvement is achieved by the design according to the invention.

[0012] In one embodiment of the present invention, the booster unit comprises a high-pressure reservoir connected to the bottom space via a flow control valve in a second adjustment direction. This allows the piston of the casting cylinder to be loaded with high pressure in the extension direction. This second adjustment direction allows for a pressure reduction in the regeneration circuit and during pressure maintenance.

[0013] In an alternative solution, the boost unit is designed as a pressure booster (multiplier), whose booster piston defines a pressure booster annular chamber and a pressure booster pressure chamber, which can be connected to a low-pressure accumulator via a shutoff valve or the like for acceleration. A flow control valve can be used to connect the pressure medium of the pressure booster annular chamber to the tank line in a second adjustment direction.

[0014] The flow control valve can be designed, for example, as an electro-hydraulic pre-controlled three-way flow control valve.

[0015] In one embodiment of the invention, the shutoff valve arrangement is designed as a 2 / 2-way active logic with an auxiliary valve. The active logic allows the pressure medium connection between the low-pressure reservoir and the bottom chamber of the casting cylinder to be shut off or opened, and during pressure buildup in phase III, the pressure medium connection is closed very quickly, allowing the mold filling phase to be terminated very quickly and accurately.

[0016] In an alternative solution, the shutoff valve arrangement is designed with a shutoff valve arranged downstream of the low-pressure source instead of active logic, with a non-return valve arranged between this shutoff valve and the bottom chamber of the casting cylinder. The shutoff valve blocks and opens the connection to the casting cylinder. The non-return valve closes the connection during the pressure buildup in phase III.

[0017] According to an advantageous embodiment of the invention, the pressure in the bottom space can be reduced toward the tank T via a switching valve.

[0018] The outlet valve can be designed as a two-way flow regulating valve with electro-hydraulic pre-control. The outlet control can also be carried out by other components, for example by a valve that can be adjusted by a servomotor.

[0019] For prestressing and for charging the low-pressure accumulator and / or the high-pressure accumulator, the casting unit according to the invention is designed with a hydraulic pump, which can be designed as a regulating pump or a fixed-displacement pump with a servo motor and a servo inverter or as a regulating pump with a three-phase electric motor and a frequency converter or as a regulating pump with a three-phase electric motor.

[0020] To avoid starting pressures during the pre-charging phase, the casting unit according to the invention can also be designed with a device for pre-stressing the piston and annular sides of the casting cylinder and / or a pressure intensifier. The gentle introduction movement can also be controlled by a continuous valve or a shut-off valve on the inlet side and a damper connected downstream of the shut-off valve, or by a pump.

[0021] For this purpose, for example, a back-pressure valve can be used, via which the pressure connection of the pump can be connected to the annular chamber of the casting cylinder or the annular chamber of the pressure intensifier for prestressing. Prestressing can also be achieved simply by appropriately controlling the pump. This type of control can also be used for loading the accumulator.

[0022] In one embodiment of the invention, the bottom-side pressure chamber of the pressure intensifier is directly connected to the tank or to the pressure connection of the pump via two switching valves, for example, designed as seat valves.

[0023] Preferred exemplary embodiments of the present invention are explained in more detail below with reference to schematic diagrams. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the casting unit;

[0025] Figure 2 is a simplified hydraulic circuit diagram of the first embodiment;

[0026] Figure 3 Yes Figure 2 A hydraulic circuit diagram of a variant of the embodiment of

[0027] Figure 4 Yes Figure 2 A hydraulic circuit diagram of another variant of the embodiment of FIG. DETAILED DESCRIPTION

[0028] exist Figure 1 1 shows the essential mechanical components of the hydraulic casting unit 1 according to the invention of a die-casting machine.

[0029] Accordingly, the casting unit 1 comprises a casting cylinder 10 designed as a differential cylinder, and its piston 11 is correspondingly designed with a piston rod 12. The piston 11 and the casting cylinder housing 13 together define a bottom space 14 on the bottom side and an annular chamber 15 penetrated by the piston rod 12. A casting piston 16 is secured to the end section of the piston rod 12 protruding from the housing 13. This casting piston 16 is inserted into a shot chamber 18 of a casting bushing 17. Located in this shot chamber is a charging opening 19 for the liquid or pasty molding material, hereinafter referred to as the melt, from which the workpiece to be molded is to be formed. The casting bushing 17 is attached to a mold 20, which typically consists of a movable and a stationary mold half. The two mold halves define a mold cavity 21, also called a die, which is designed according to the geometry of the workpiece to be molded. The shot chamber 18 opens into the mold cavity 21 via a casting channel 22.

[0030] Such a casting unit 1 is used to introduce a melt into a mold 20 , wherein due to the rapid solidification process a high speed is required for the charging and subsequently a high pressure is required to completely fill the mold 20 and to compress and compensate for the shrinkage of the material during solidification.

[0031] exist Figure 2 In the illustrated embodiment of the invention, a pressure intensifier 24, also called a multiplier, is assigned to the casting cylinder 10 as a booster unit. The pressure intensifier is designed, for example, as a differential cylinder. The primary piston 26 defines a pressure intensifier pressure chamber 28 with its base, and a piston rod 30 extends through a pressure intensifier annular chamber 32. The design of such a pressure intensifier 24 is known and therefore requires no further explanation.

[0032] The pressure medium supply to the shown casting unit 1 is provided by a hydraulic pump 34, which in the shown embodiment is designed as a fixed displacement pump and is driven by a speed-controlled electric motor 36, for example, designed as a servomotor with a servo converter or a three-phase electric motor with a frequency converter. The pressure connection of the hydraulic pump is connected to the bottom chamber 14 via a pump line 40 and a shutoff valve 42 arranged therein, designed as a 2 / 2-way valve. In its shown spring-prestressed basic position, the shutoff valve 42 blocks the pressure medium connection between the hydraulic pump 34 and the bottom chamber 14 and can be moved into a free-flowing position by means of a switching magnet.

[0033] The annular chamber 15 of the casting cylinder 10 is connected to the tank T via a line 44, wherein an outlet valve 46 is arranged in this line. In the exemplary embodiment shown, this outlet valve is designed as an electrohydraulically pre-controlled 2 / 2 flow control valve, which in its basic position blocks the pressure medium connection to the tank T and, by controlling the electrohydraulic pre-control, switches the opening cross section to the tank T in accordance with a control signal.

[0034] The line 44 and the pump line 40 are connected via a backpressure valve 48 designed as a 2 / 2-way valve, which is arranged in a pretensioning line 50. This pretensioning line is blocked in the spring-prestressed basic position of the backpressure valve 48 and can be switched on by actuating a switching magnet of the backpressure valve 48. By appropriately actuating the backpressure valve 48, the casting cylinder 10 can also be retracted.

[0035] The pressure at the outlet of the hydraulic pump 34 is limited in a manner known per se by a pressure-limiting valve 52 which opens toward the tank T.

[0036] According to the present invention, a flow control valve 54 is associated with the pressure intensifier 24 and the casting cylinder 10. In the illustrated embodiment, the flow control valve is designed as a continuously adjustable, electrohydraulically pre-controlled installation control valve (three-way flow control valve) with three connections. This flow control valve has a first connection 541, a second connection 542, and a third connection 543.

[0037] The flow control valve 54 has a position in which the pressure medium connection between the first connection 541, the second connection 542 and the third connection 543 is closed. By corresponding actuation, the control slide of the flow control valve 54 can be adjusted in the sense of connecting the pressure medium connection between the first connection 541 and the third connection 543. In the case of corresponding actuation, the pressure medium connection from the second connection 542 to the third connection 543 is connected (see Figure 2 ).

[0038] In the illustrated embodiment, the second port 542 is connected to the pressure intensifier annular chamber 32 via a line 56. A pressure line 58 opens into the line section 41 extending downstream of the shutoff valve 42 and leads to port B of a pre-controlled 2 / 2-way seat valve designed as active logic 60. The pre-control is accomplished via a pilot valve 62 designed as a 4 / 2-way valve. Input port A of the active logic 60 is connected to a low-pressure accumulator 66 via a low-pressure accumulator line 64. The active logic 60 can also be installed in reverse with respect to ports A and B.

[0039] One possible design of active logic 60 is known from the documents DE 10 2017 220 832 A1 and DE 10 2005 035 170 B4 cited in the introduction to this specification. Therefore, only the structural elements essential for understanding the present invention will be explained here, and reference is made to this prior art for the remainder. Accordingly, active logic 60 includes a stepped main piston 70, which is prestressed against valve seat 68 by the pressure from the low-pressure accumulator ND toward surface A5 and interrupts the pressure medium connection between connections A and B, and thus between the low-pressure accumulator line 64 and the pressure line 58. Active logic 60 can also be designed, for example, with two control surfaces and pressure equalization, as well as a switching pilot valve (see DE 10 2017 220 832 A1 and DE 10 2005 035 170 B4).

[0040] The tank line 84 is connected to the tank connection of the pilot valve 62, and the input connection of the pilot valve 62 is connected via a line 88 to a pressure accumulator 90, which is pressurized to a higher pressure than the low-pressure accumulator 66. By energizing the switching magnet of the pilot valve 62, the pilot valve can be adjusted against the force of a spring into a switching position in which the annular control chamber of the active logic 60 is connected to the accumulator 90. As a result, due to the higher pressure in the accumulator 90 acting on the annular end surface A4, the main piston 70 is lifted from the valve seat 68 and a fluid connection is established between the connections A and B. In the above-described alternative embodiment of the active logic 60 with two control surfaces, a higher control pressure does not necessarily have to be provided.

[0041] Alternatively, the annular end face A4 defining the annular control chamber can also be designed with a larger effective surface than the area difference A5-A3, in which case it is sufficient to connect the annular control chamber to the low-pressure reservoir 66 in the switching position of the pilot valve 62 (see Figure 3 ), because the force effective in the opening direction, which is essentially caused by the large annular end surface A4 and the surface A3, is greater than the force effective in the closing direction, which is determined by the force of the spring force and the pressure acting on the surface A5.

[0042] Active logic 60 is designed so that it can flow through with minimal pressure loss and, when appropriately actuated via pilot valve 62, can be closed very reproducibly with minimal switching times. To optimize the subsequent closing behavior, the stroke of active logic 60 can also be limited. This special design of active logic 60 requires only a small control oil flow even with large nominal dimensions in order to quickly and reproducibly open and close active logic 60.

[0043] Furthermore, operational safety is increased by actively opening and closing the active logic 60 via the pilot valve 62 and securely keeping the active logic 60 closed via the reservoir pressure. Actively closing the active logic 60 allows for free selection of the closing conditions. This closing can be effected, for example, as a function of pressure, load force, travel distance, travel speed, etc.

[0044] like Figure 2 As shown in FIG, the low-pressure accumulator line 64 can be connected in a manner known per se via a 2 / 2-way valve, hereinafter referred to as accumulator shut-off valve 92 , to the pressure booster pressure chamber 28 .

[0045] A pressure relief line 94 branches off from the pressure line 58, in which a pressure relief valve 96 is arranged. This pressure relief valve is designed as a 2 / 2-way valve and, in the illustrated spring-prestressed basic position, shuts off the pressure relief line 94 to the tank T. By energizing the switching magnet, the pressure relief valve 96 can be brought into a free position, in which a fluid connection to the tank T is established.

[0046] Next, we will explain the process during the phases mentioned at the beginning. Figure 2 The method of operation of the casting unit 1 is shown.

[0047] In order to prevent the opening of the active logic 60, also known as the accumulator shut-off valve, during the pre-charging phase when the casting cylinder 10 is started from generating a pressure wave in the direction of the casting cylinder 10 that generates a starting pressure, the casting cylinder 10 is pre-tensioned before the pre-charging phase is initiated. This is achieved by pre-tensioning the annular chamber 15 of the casting cylinder 10 and the annular chamber 32 of the pressure intensifier 24 to the maximum pump pressure in the retracted casting cylinder 10 and the pressure intensifier 24 (after the last shot) by means of the hydraulic pump 34 and the back pressure valve 48 switched to its open position and the flow control valve 54, wherein the flow control valve is pre-controlled towards the maximum pump pressure by means of an electro-hydraulic pre-control. Figure 2 The direction of the position shown is adjusted, in which a fluid connection is established between the third connection 543 and the second connection 542. The shut-off valve 42 and the back-pressure valve 48 are preferably designed with a non-return function.

[0048] In the next step, the melt is introduced into the shot chamber 18 of the casting sleeve 17 through the charging opening 19 and into the precharging phase. To this end, the hydraulic pump 34 is controlled via a ramp function and pressurizes the bottom chamber 14 of the casting cylinder 10 to the reservoir pressure via the valve 42. The casting cylinder 10 is then slowly and without starting pressure, moving outwards a little at a time against the preload, until the fluid contained in the annular chamber 15 is compressed and force equilibrium is achieved. It is crucial that this control achieves smooth pressure equalization between the low-pressure reservoir 66 and the bottom chamber 14 of the casting cylinder 10. The low-pressure reservoir 66 can then be connected to the bottom chamber 14 via the active logic 60 (accumulator shutoff valve) and to the booster pressure chamber 28 via the low-pressure shutoff valve 92.

[0049] If the hydraulic pump 34 can generate a sufficiently high pressure, this method is not necessary. In the correspondingly highly prestressed annular chamber 15, the low-pressure accumulator 66 can also be connected to the piston chamber 14 by the active logic 60.

[0050] The flow control valve 54 is then pre-controlled in a direction that connects the first and third connections 541 and 543. This allows the pressure medium expelled from the annular chamber 15 to be directly delivered to the bottom space 14 in a regenerative manner. This allows for a gentle (smooth, regenerative, and regulated) start-up and movement of the casting cylinder 10. This accelerates the melt and moves it toward the mold cavity 21. This continues until the melt reaches the mold section.

[0051] Due to the regeneration operation of the casting cylinder 10 during the precharging phase, less pressure medium is withdrawn from the low-pressure reservoir 66, so that this low-pressure reservoir can be designed with a smaller volume than in conventional solutions. In addition, the lower pressure drop at the flow control valve 54 allows for better resolution of the casting cylinder speed, so that the casting cylinder 10 can be operated at a lower speed.

[0052] A further advantage of the regeneration mode is that, due to the lower pressure loss at the flow control valve 54 and due to the fact that the pressure medium does not flow out of the annular chamber 15 against the tank pressure (0 bar), but against the pressure in the low-pressure reservoir 66, less cavitation and therefore less wear occurs at the piston 11 and at the housing 13 of the casting cylinder and at the associated control block.

[0053] Furthermore, the pressure in the bottom space 14 can be actively influenced, meaning by reducing the pressure, by suitable actuation of the flow control valve 54 .

[0054] Once the melt reaches the mold cross-section, the actual mold filling process begins (Phase II). During mold filling (injection) at a low mold filling force, regenerative operation is also performed. Accordingly, at the time the melt reaches the mold cross-section, the flow control valve 54 is adjusted, for example using a jump function, to a position in which the pressure medium connection between the annular chamber 14 and the base chamber 15 is further opened, so that the melt is injected into the mold 20 at a high injection speed (up to 10 m / s). Regenerative operation is also performed here, meaning that the pressure medium displaced from the annular chamber 15 is supplied to the enlarged base chamber 14.

[0055] This has the advantage that less pressure medium must be withdrawn from the low-pressure accumulator 66 in phase II than is the case with conventional solutions.

[0056] When injection is performed at a high mold filling force, at the time when the melt reaches the mold cross section, the flow control valve 54 is moved into its closed position, for example using a jump function, thereby interrupting the pressure medium connection between the annular chamber 15 and the bottom space 14. In parallel, the flow control valve 46 in the outlet is opened, for example using a jump function, to a predetermined opening cross section toward the tank T. This results in the melt being injected into the mold cavity 21 at a high injection speed, wherein, in contrast to the approach with a low mold filling pressure, there is no regenerative operation and the maximum force of the casting cylinder 10 can therefore be utilized.

[0057] In principle, a mixed model is also conceivable, in which the flow control valve 54 is adjusted into its blocking position only during the first phase II, depending on the load force.

[0058] Phase II can also be operated in a fully regenerative manner. However, this presupposes that the required load force in phase II can also be achieved in the regeneration circuit. In this case, the flow control valve 46 can be replaced by a fast-opening valve for relieving the annular chamber 15 in phase III.

[0059] After the mold cavity 21 is completely filled, the transition to phase III begins. To this end, at the end of mold filling, the flow control valve 54 is pre-controlled in the open direction, connecting the connection from 3 to 2. This connects the pressure booster annular chamber 32 to the line 44 via the flow control valve 54. Simultaneously with the adjustment of the flow control valve 54, the flow control valve 46 is connected to the tank T. This releases the pressure from the pressure booster annular chamber 32, accelerating the primary piston 26 and correspondingly building up a high pressure in the bottom chamber 14. This pressure acts on the piston 11, and the melt is recompressed. After the desired holding pressure is reached, the flow control valve 54 is reset to the closed position by the pressure regulator. If the flow control valve 54 is not closed quickly enough, the pressure overshoot could be reduced by opening the connection from 1 to 3.

[0060] Thus, the flow control valve 54 has a dual function, i.e., on the one hand, it controls the regenerative connection between the annular chamber 15 and the bottom space 14 and, on the other hand, it introduces the acceleration of the pressure intensifier 24 (multiplier). This dual function makes it possible to omit the control valve compared to the solution described above.

[0061] Figure 3 Shows the Figure 2 The hydraulic circuit diagram of a variant of the casting unit 1 is shown in FIG. Figure 3 In the exemplary embodiment, the boost unit is not formed by the pressure intensifier 24, but by a high-pressure accumulator 98, which can be connected via a high-pressure accumulator valve 100. Figure 3 In the embodiment shown, the flow control valve 54 can also be adjusted by its electrohydraulic precontrol against the force of the spring into the shown position, in which a fluid connection is established between the first connection 541 and the third connection 543, so that the annular chamber 15 is connected to the bottom space 14 and the casting cylinder 10 can be operated regeneratively. The flow control valve 54 can open a connection between the first connection 541 and the second connection 542, wherein the high-pressure accumulator line 102 is connected to the second connection 542, in which the high-pressure accumulator valve 100 is arranged.

[0062] In addition, the hydraulic pump 34 is Figure 3 In the embodiment, the pump is designed as a regulating pump of a shaft piston structure. Correspondingly, the electric motor 36 is designed as a quantitative motor. Of course, it is also possible to adjust the pump in accordance with the embodiment. Figure 3 In the circuit, use Figure 2 A metering pump with an illustrated drive variant.

[0063] In addition, press Figure 3 The embodiments basically correspond to Figure 2 Therefore, with regard to the functions and structures of the remaining components, reference can be made to the above statements.

[0064] Before the start of phase I, a pressure medium connection can be opened between the second connection 542 of the flow control valve 54 and the high-pressure accumulator 98 via the high-pressure accumulator valve 100. However, this high pressure does not act in the bottom space 14, so the second connection 542 is blocked. This bottom space 14 is connected to the annular chamber 15 via the flow control valve 54 as explained above, thus completing the regeneration operation of the casting cylinder 10. Figure 2 The working method of the casting unit 1 is similar to the description.

[0065] In order to transition to phase III, the high-pressure reservoir 98 is then connected. This is done by adjusting the flow control valve 54 in a direction in which the direct connection between the annular chamber 15 and the bottom space 14 is disconnected and the fluid connection between the second connection 542 and the first connection 541 is connected, so that high pressure is effective in the bottom space 14 accordingly. At the same time, the flow control valve 46 in the outlet is opened so that the pressure medium squeezed out of the annular chamber 15 can flow out to the tank T. The use of the high-pressure reservoir 98 eliminates the expensive acceleration of the conventional pressure booster 24 in phase III, so that only a small amount of pressure medium and therefore only a small amount of energy is required for acceleration. The flow control valve 54 in the inlet to the casting cylinder 10 must here be opened shortly before the required pressure is built up from 1 to 2. Since the moving mass of the pressure booster 24 must be eliminated and therefore does not have to be braked, the pressure build-up can be faster than in the case of pressing Figure 2 In the embodiment of the present invention, the pressure is increased more dynamically. The control quality is also improved. Another advantage is that the additional dead volume on the casting cylinder side for inserting the piston rod 30 of the pressure intensifier 24 is eliminated, and the pressure medium required to operate the pressure intensifier 24 based on the pressure intensifier's area is not required. Therefore, with the same volume flow rate at the inlet, the pressure build-up can be achieved much faster. Furthermore, this allows the use of a flow control valve 54 designed with a smaller nominal size. Charging the high-pressure accumulator 98 can be accomplished, for example, by a high-pressure pump or a pressure intensifier.

[0066] Figure 4 Shows the Figure 2, in which the bottom-side pressure booster pressure chamber 28 can be connected to the pump line 40 via a switching valve 104 and to the tank T via a further switching valve 106. In the basic position shown, the two switching valves 104, 106 are prestressed into their blocking position and can each be moved into the open position by energizing a switching magnet, so that the pressure booster pressure chamber 28 is either charged with the pressure at the outlet of the hydraulic pump 34 (the switching valve 104 is closed) or relieved of pressure toward the tank T (the switching valve 106 is in the open position).

[0067] according to Figure 4 The remaining embodiments correspond to Figure 2 The present invention is an illustrative embodiment and therefore no further explanation is necessary.

[0068] The described casting unit has the advantage over conventional solutions that, during the regenerative operation of the casting cylinder 10, the pressure medium displaced from the annular chamber 15 can be supplied directly to the bottom chamber 14 of the casting cylinder 10 via the flow control valve 54. The pressure buildup and pressure reduction in phase III can also be controlled via this flow control valve 54. Another special feature is the active deactivation of the active logic 60 at the end of phase II.

[0069] Active logic can also be replaced by a shut-off valve and an external non-return valve.

[0070] Disclosed is a casting unit whose casting cylinder can be regenerated in a pre-charging phase by means of a flow control valve. An enhancement unit, such as a pressure booster or a high-pressure accumulator, is also connected in a pressure-maintaining phase by means of this flow control valve.

[0071] Reference Signs List

[0072] 1 Casting unit

[0073] 10 Casting cylinder

[0074] 11 Piston

[0075] 12 piston rod

[0076] 13 Housing

[0077] 14 Bottom space

[0078] 15 Ring Room

[0079] 16 Cast piston

[0080] 17 Cast bushing

[0081] 18 Injection Chamber

[0082] 19 Loading opening

[0083] 20 Models

[0084] 21 Model cavity

[0085] 22 Casting Channel

[0086] 24 Booster / Multiplier

[0087] 26 Primary Piston

[0088] 28 Booster pressure chamber

[0089] 30 piston rod

[0090] 32 Supercharger annular chamber

[0091] 34 hydraulic pumps

[0092] 36 Electric Motor

[0093] 40 Pump line

[0094] 41 pipeline section

[0095] 42 stop valve

[0096] 44 pipelines

[0097] 46 Flow control valve (outlet valve)

[0098] 48 Back pressure valve

[0099] 50 Pre-tensioned pipeline

[0100] 52 pressure limiting valve

[0101] 54 Flow Control Valve

[0102] 541 First Connector

[0103] 542 Second connector

[0104] 543 Third connector

[0105] 56 connecting pipelines

[0106] 58 pressure line

[0107] 60 Active Logic

[0108] 62 Auxiliary valve

[0109] 64 low-voltage memory pipelines

[0110] 66 Low Voltage Memory

[0111] 68 valve seat

[0112] 70 Main piston

[0113] 84 Material tank pipeline

[0114] 88 pipeline

[0115] 90 Memory

[0116] 92 Storage shut-off valve

[0117] 94 pressure relief line

[0118] 96 Pressure Relief Valve

[0119] 98 High-voltage storage

[0120] 100 High-pressure storage valve

[0121] 102 High-voltage memory pipeline

[0122] 104 On / Off Valve

[0123] 106 Additional switching valve.

Claims

1. A hydraulic casting unit of a prototype machine, comprising: a casting cylinder (10) designed as a differential cylinder, the piston (11) of which defines a bottom space (14) on the bottom side and an annular chamber (15) on the piston rod side; a regulating valve designed to connect the annular chamber (15) to the bottom space (14); and a regulating valve for connecting a line (44) connected to the annular chamber (15) to a tank (T); and a low-pressure source, which can be connected to the bottom space (14) via a shut-off valve device; and a hydraulic boost unit designed to support the extension movement of the casting cylinder (10) during the holding pressure phase, characterized in that The regulating valve designed to connect the annular chamber (15) to the bottom space (14) is designed as a flow regulating valve (54), the slide valve of which connects the pressure medium connection between the bottom space (14) and the annular chamber (15) in one adjustment direction and activates the enhancement unit in another adjustment direction, wherein the enhancement unit is a pressure booster (24), the primary piston (26) of which defines the pressure booster annular chamber (32) with a smaller end face and defines the pressure booster pressure chamber (28) with a larger end face, and the pressure booster pressure chamber can be connected to a low-pressure source via a storage shut-off valve (92), wherein the pressure medium connection of the pressure booster annular chamber (32) to the pipeline (44) can be connected in the other adjustment direction via the flow regulating valve (54).

2. The casting unit according to claim 1, wherein: The flow control valve (54) is designed as a three-way flow regulating valve that is pre-tightened electro-hydraulically.

3. The casting unit according to claim 1, wherein: The shut-off valve device is designed as a 2 / 2-way active logic (60) with an auxiliary valve (62).

4. The casting unit according to claim 1, wherein: The shut-off valve device is designed as a valve device having a shut-off valve assigned to a low-pressure source and a non-return valve arranged between the shut-off valve and the bottom space (14) of the casting cylinder (10).

5. The casting unit according to claim 1, comprising a storage shut-off valve (92) for connecting the pressure medium flow path between the output of the shut-off valve device and the bottom space (14) of the casting cylinder (10) and the material tank (T).

6. The casting unit according to claim 1, comprising a storage shut-off valve (92), which is used to connect the output end of the switching active logic (60) and the pressure medium flow path between the bottom space (14) of the casting cylinder (10) and the material tank (T).

7. The casting unit according to claim 1, wherein: The outlet valve (46) is designed as a two-way flow control valve which is electro-hydraulically pre-controlled.

8. The casting unit according to claim 1, comprising a hydraulic pump (34), wherein: The hydraulic pump is designed as a regulating pump or a fixed displacement pump with a servomotor and a servo converter, or as a regulating pump with a three-phase motor and a frequency converter, or as a regulating pump with a three-phase motor.

9. The casting unit according to claim 1, comprising a device for prestressing the casting cylinder (10) and / or the pressure intensifier (24).

10. The casting unit according to claim 8, comprising a back-pressure valve (48), which is designed to connect the pressure connection of the hydraulic pump (34) to the pressure intensifier annular chamber (32) and / or to the annular chamber (15) of the casting cylinder (10) via the flow control valve (54).

11. The casting unit according to claim 1, wherein: The prototype machine is an injection molding machine, a die casting machine or a thixomolding machine.

Images