Die casting machine oil passage system with dual accumulators

Abstract

The present invention discloses a dual accumulator oil passage system for a die casting machine, which belongs to the technical field of die casting machine control. The dual accumulator oil passage system includes an injection cylinder and an accumulator, and further includes a booster accumulator. The booster accumulator includes a booster chamber and an annular chamber. The booster chamber is connected to a rodless cavity of the injection cylinder. The accumulator is connected to the annular chamber of the booster accumulator via a first servo valve. The annular chamber is connected to an oil tank via a second servo valve. The rod-equipped cavity of the injection cylinder is connected to the oil tank via a third servo valve. In this technical solution, the first and second servo valves form an A-bridge control for the boost accumulator, and by controlling the pressure in the annular chamber of the boost accumulator, the magnitude of the boost injection force of the injection cylinder can be controlled. The third servo valve can control the oil discharge from the rod-equipped cavity of the injection cylinder, thereby controlling the injection speed of the injection cylinder. This technical solution can achieve accurate control of the injection speed and injection force by using only three servo valves.

Description

[Technical Field]

[0001] The present invention relates to a control system for a die casting machine, and more particularly to a die casting machine oil passage system with dual accumulators. [Background technology]

[0002] For the injection system of a die casting machine, using inlet control at low speeds can avoid starting shock, and using differential control at low speeds can reduce accumulator oil consumption and also reduce oil throttling and heat generation. Using outlet control at high speeds can achieve multi-stage adjustment in the high-speed range and improve the flexibility of speed adjustment in the high-speed stage. Using hydraulic A-bridge control in the boosting stage can not only achieve high-precision adjustment of boosted injection power but also achieve stepless adjustment of boosted injection power. Die casting technical means can be customized according to the process. To achieve the above functions, the prior art requires the installation of multiple servo valves, namely, one for inlet control, one for outlet control, and two for boosted A-bridge control, for a total of at least four servo valves.

[0003] For example, Chinese Patent Publication No. CN118305295A, entitled "Injection Control Oil Channel, Die Casting Machine, and Injection Control Method," discloses a die casting machine control oil channel including an oil supply system, a cartridge valve, and a servo valve, wherein the servo valve is connected to the rod-equipped cavity of the injection cylinder, and the injection cavity is connected to the rod-equipped cavity; when the injection control oil channel is in an outlet-throttling state, the cartridge valve is fully open, and a control device adjusts the opening of the servo valve to control the injection speed; when the injection control oil channel is in an inlet-throttling state, the servo valve is fully open, and hydraulic oil adjusts the opening of the cartridge valve to control the injection speed; by using this injection control oil channel, the die casting machine can have two speed adjustment modes: outlet throttling and inlet throttling. However, the die casting machine's injection speed and injection force control precision is low and flexibility is low, making the die casting product prone to defects. Summary of the Invention

[0004] The present invention overcomes the problem of low injection control accuracy in conventional die casting machines and provides a die casting machine oil passage system with dual accumulators. This technical solution achieves accurate control of injection speed and injection force using only three servo valves, thereby improving the injection performance of the die casting machine.

[0005] The present invention uses the following technical means to solve the above technical problems: A die-casting machine oil passage system with dual accumulators includes an injection cylinder and an accumulator, and further includes a booster accumulator, the booster accumulator including a booster chamber and an annular chamber, the booster chamber communicating with a rodless cavity of the injection cylinder, the accumulator communicating with the annular chamber of the booster accumulator via a first servo valve, the annular chamber communicating with an oil tank via a second servo valve, and the rod-equipped cavity of the injection cylinder communicating with the oil tank via a third servo valve. In this technical solution, the first and second servo valves form an A-bridge control for the booster accumulator, and by controlling the pressure in the annular chamber of the booster accumulator, the magnitude of the boosted injection force of the injection cylinder can be controlled. The third servo valve controls the oil discharge from the rod-equipped cavity of the injection cylinder, thereby controlling the injection speed of the injection cylinder. This technical solution can achieve accurate control of the injection speed and injection force using only three servo valves, and improve the injection performance of the die casting machine.

[0006] Preferably, a differential circuit is formed between the rod-equipped cavity of the injection cylinder and the rodless cavity of the injection cylinder by a first servo valve, and the differential circuit is formed between the rod-equipped cavity of the injection cylinder and the rodless cavity of the injection cylinder, and the first servo valve controls the oil flow rate in the differential circuit, and further controls the low-speed injection of the injection cylinder, thereby reducing and even eliminating the starting shock of the die-casting machine.

[0007] Preferably, the die casting machine oil passage system with dual accumulators further includes a valve assembly, the valve assembly including valves V1 and V3, the valves V1 and V3 being arranged in the differential circuit, with the valve V1 arranged on the rod-equipped cavity side of the injection cylinder and the valve V3 arranged on the rodless cavity side of the injection cylinder. Valve V1 is a differential valve, and during the low-speed injection phase, the valves V1, V3, and the first servo valve are energized to form a differential circuit between the rod-equipped cavity and the rodless cavity of the injection cylinder, allowing oil in the accumulator to flow through valves V4 and V3 into the rodless cavity of the injection cylinder. By adjusting the opening of the first servo valve, the injection speed during the low-speed injection phase can be adjusted and the movement of the piston rod in the injection cylinder can be slowed.

[0008] Preferably, the valve assembly further includes a valve V2, the accumulator connects the first servo valve and the valve V3 in series to form a first oil passage together with the rodless cavity of the injection cylinder, and the accumulator forms a second oil passage together with the rodless cavity of the injection cylinder through the valve V2. The first oil passage is an oil passage through which the accumulator supplies oil to the rodless cavity of the injection cylinder through the first servo valve, and the second oil passage is a main oil passage through which the accumulator supplies oil to the rodless cavity of the injection cylinder.

[0009] Preferably, the die casting machine oil passage system with dual accumulators further includes an oil pump, and the valve assembly further includes a valve V15, where the oil pump forms a third oil passage together with the annular chamber of the boost accumulator through the valve V15, and the oil pump forms a fourth oil passage together with the boost chamber of the boost accumulator through the valve V15. The third and fourth oil passages allow energy to be stored in the annular chamber and the boost chamber of the boost accumulator, thereby enabling better boost control.

[0010] Preferably, the valve assembly further includes a valve V16, and the oil pump forms a fifth oil passage together with the accumulator via the valve V16. The fifth oil passage is an oil passage through which the oil pump stores energy in the accumulator, and oil supply control can be performed by the accumulator and the booster accumulator in subsequent oil passage control.

[0011] Preferably, the valve assembly further includes a valve V8, and the accumulator is configured such that the first servo valve and the valve V8 are connected in series to form a sixth oil passage together with the annular chamber of the boost accumulator. Oil in the accumulator flows into the boost accumulator through the sixth oil passage, providing sufficient oil for boost control of the boost accumulator, thereby realizing boost control.

[0012] Preferably, the valve assembly further includes a valve V5, the annular chamber of the boost accumulator communicates with the second servo valve to form a seventh oil passage together with the oil tank, and the boost chamber of the boost accumulator communicates with the valve V5 to form an eighth oil passage together with the rodless cavity of the injection cylinder. The eighth oil passage provides boost pressure to the injection cylinder through the boost accumulator, and the opening of the second servo valve in the seventh oil passage may be adjusted, thereby adjusting the boost effect of the eighth oil passage on the injection cylinder to achieve precision adjustment of the injection force.

[0013] Preferably, the valve assembly further includes a valve V13, and the oil pump sequentially connects the valves V13 and V3 to form a ninth oil passage together with the rodless cavity of the injection cylinder. The ninth oil passage supplies oil from the oil pump and introduces the oil into the rodless cavity of the injection cylinder via the valves V13 and V3, and the oil in the rod-equipped cavity of the injection cylinder returns to the oil tank via the third servo valve, allowing the manual plunger advance operation of the die-casting machine before startup.

[0014] Preferably, the valve assembly further includes a valve V14 and a valve V12, the oil pump communicating the valve V12 with the rod-equipped cavity of the injection cylinder to form a tenth oil passage, and the injection cylinder connecting the valves V3 and V14 in series to form an eleventh oil passage together with the oil tank. The tenth oil passage introduces oil from the oil pump into the rod-equipped cavity of the injection cylinder, and the eleventh oil passage introduces oil from the rodless cavity of the injection cylinder into the oil tank, thereby enabling manual or plunger retraction of the die casting machine.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) By using only three servo valves, precise control of injection speed and injection force can be achieved, improving the injection performance of the die casting machine; (2) The impact of starting the die casting machine is small and the operation is smooth; (3) In the high-speed stage, multi-stage adjustment in the high-speed range can be achieved by using outlet control, improving the flexibility of speed adjustment in the high-speed stage. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram of an oil passage system of the present invention. [Figure 2] 1 is a schematic diagram of the oil passages in the manual plunger advancement stage of the present invention. FIG. [Figure 3] 10 is a schematic diagram of the oil paths during the manual plunger retraction and automatic plunger return phases of the present invention. FIG. [Figure 4] FIG. 2 is a schematic diagram of the oil passage in the injection energy storage stage of the present invention. [Figure 5] FIG. 2 is a schematic diagram of the oil passages in the boost energy storage stage of the present invention. [Figure 6] FIG. 2 is a schematic diagram of the oil passages in the low speed injection stage of the present invention. [Figure 7] 1 is a schematic diagram of the oil passages in the high speed injection stage and the braking stage of the present invention. FIG. [Figure 8] FIG. 2 is a schematic diagram of the oil passages in the boosting stage of the present invention. [Figure 9] 2 is a schematic diagram of an oil path in the tracking stage of the present invention; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] The technical means of the present invention will be described in more detail below with reference to the drawings and specific examples.

[0018] Example 1 The die casting machine oil passage system with dual accumulators as shown in Figures 1 to 9 includes an injection cylinder 1, an accumulator 3, and a booster accumulator 2. The accumulator 3 and the booster accumulator 2 are connected to the oil passage on the inlet side of the rodless cavity of the injection cylinder 1 to perform inlet control for the injection cylinder 1, and the accumulator 3 and the injection accumulator 2 store hydraulic energy and can perform oil control for the injection cylinder 1. Specifically, the booster accumulator 2 includes a booster cylinder, the interior of which is a convex cavity, and a piston rod is slidably provided inside the booster cylinder. The side of the rod end of the piston rod away from the piston and the convex end of the booster cylinder form a booster chamber, and the side of the piston rod close to the rod end of the piston and the booster cylinder form an annular chamber. The die-casting machine injection oil passage system further includes an oil pump and an oil tank, the oil pump can supply oil to the entire die-casting machine injection oil passage system, and the oil tank is the oil return structure of the entire die-casting machine injection oil passage system.

[0019] As shown in the figure, the die casting machine injection oil passage system includes a total of 16 hydraulic valves, designated valves V1 to V16. Valve V1 is a differential valve, valve V2 is a large-diameter active cartridge valve, valve V3 is a general cartridge valve, valve V3 has the feature of high pressure resistance, valve V4 is a first servo valve, the opening of valve V4 is adjustable, valve V5 is an oil supply valve that supplies oil to the rodless cavity of the injection cylinder 1 in the booster oil passage control, valves V6, V10 and V11 are safety valves, valves V6, V10 and V11 are normally open hydraulic valves, valve V7 is a second servo valve, the opening of valve V7 is adjustable, and valve V8 is a booster accumulator by accumulator 3. Valve V9 is an oil supply valve that supplies oil to the annular chamber of booster accumulator 2, valve V9 is a third servo valve, and the opening of valve V9 is adjustable. Valve V12 is an oil supply valve that supplies oil to the rod-equipped cavity of injection cylinder 1 by an oil pump. Valve V13 is an oil supply valve that supplies oil to the rodless cavity of injection cylinder 1 by an oil pump. Valve V14 is an oil return valve that returns oil from the rodless cavity of injection cylinder 1 to the oil tank. Valve V15 is an oil supply valve that supplies oil to the booster chamber and annular chamber of booster accumulator 2 by an oil pump. Valve V16 is an oil supply valve that supplies oil to accumulator 3 by an oil pump. The first and second servo valves form an A-bridge control for the boost accumulator 2, and by controlling the pressure in the annular chamber of the boost accumulator 2, the magnitude of the boost injection force of the injection cylinder 1 can be controlled at different levels. The third servo valve controls the oil discharge from the rod-equipped cavity of the injection cylinder 1, thereby controlling the injection speed of the injection cylinder 1. This technical solution uses only three servo valves to achieve accurate control of the injection speed and injection force of the die casting machine, thereby improving the injection performance of the die casting machine.Valves V6, V10 and V11 remain energized in a non-pressure-released state and are closed, thereby providing protection to the oil line system and facilitating draining and maintenance of the oil line system.

[0020] The die-casting machine injection oil passage system further includes multiple oil passages. Specifically, a differential circuit is formed between the rodless cavity of the injection cylinder 1 and the rod-equipped cavity of the injection cylinder 1. The differential circuit supplies oil via the accumulator 3. The accumulator 3 connects valves V1, V4, and V3 in series from the rod-equipped cavity of the injection cylinder 1 to the rodless cavity of the injection cylinder 1, forming a differential circuit together with the rodless cavity of the injection cylinder 1. The differential circuit gradually activates the piston rod of the injection cylinder 1 during the low-speed injection phase, reducing startup shock. The accumulator 3 connects the first servo valve (valve V4) and valve V3 in series in series to form a first oil passage together with the rodless cavity of the injection cylinder 1. As part of the differential circuit, the first oil passage can adjust the amount of oil flowing from the accumulator 3 into the injection cylinder 1 by adjusting the opening of the first servo valve. The accumulator 3 communicates with the valve V2 to form a second oil passage with the rodless cavity of the injection cylinder 1. The second oil passage is the main oil passage through which the accumulator 3 supplies oil to the rodless cavity of the injection cylinder 1. The valve V2 has a large bore. The oil pump communicates with the valve V15 to form a third oil passage with the annular chamber of the boost accumulator 2. The oil pump also communicates with the valve V15 to form a fourth oil passage with the boost chamber of the boost accumulator 2. The third and fourth oil passages are oil passages through which the oil pump supplies oil to the boost accumulator 2 and stores pressure for the boost accumulator 2. As can be seen, the third and fourth oil passages are parallel oil passages. The oil pump communicates with the valve V16 to form a fifth oil passage with the accumulator 3. The fifth oil passage is an energy storage oil passage through which the oil pump supplies oil to the accumulator 3. The accumulator 3 is connected in series with the first servo valve (valve V4) and valve V8 to form a sixth oil passage together with the annular chamber of the boost accumulator 2. The sixth oil passage is an oil passage through which the accumulator 3 supplies oil to the boost accumulator 2, allowing the boost accumulator 3 to provide sufficient oil pressure.The annular chamber of the boost accumulator 3 communicates with the second servo valve (valve V7) and the oil tank to form the seventh oil passage, which is a return oil passage to the boost chamber of the boost accumulator 2 and, because the opening of the second servo valve is adjustable, also serves as an oil passage for controlling the injection force of the injection cylinder 1 during boost control. The boost chamber of the accumulator 3 communicates with valve V5 and then forms the eighth oil passage together with the rodless cavity of the injection cylinder 1, which is a boost oil passage that provides the boost effect to the injection cylinder 1 by the boost accumulator 2. The oil pump connects valves V13 and V3 in series to form the 9th oil passage together with the rodless cavity of the injection cylinder, and the rod-equipped cavity of the injection cylinder 1 communicates with the third servo valve (valve V9) and the oil tank to form the main return oil passage, and the 9th oil passage and the main return oil passage gradually extend the piston rod of the injection cylinder 1, allowing the manual plunger advance operation. The oil pump communicates with the valve V12 and then forms a tenth oil passage together with the rod-equipped cavity of the injection cylinder. The tenth oil passage is an oil passage through which oil is supplied to the rod-equipped cavity of the injection cylinder 1 by the oil pump. The rodless cavity of the injection cylinder 1 is connected in series with the valves V3 and V14 in order, and then forms an eleventh oil passage together with the oil tank. The eleventh oil passage is an oil passage through which oil is returned from the rodless cavity of the injection cylinder 1. The tenth and eleventh oil passages allow the piston rod in the injection cylinder 1 to gradually retract, enabling manual or automatic plunger return operation.

[0021] As can be seen, only one oil port is provided in each of the rod-equipped cavity and rodless cavity of the injection cylinder 1, and only one oil port is provided in each of the booster chamber and annular chamber of the booster accumulator 2. Therefore, when the above oil passages are connected to the corresponding cylinders, the oil pipes join together to form one main oil pipe, which is then connected to the oil port of the injection cylinder 1 or the booster accumulator 2.

[0022] In this technical solution, the working process of the die casting machine includes a manual plunger advance stage, a manual plunger retreat stage, an injection energy storage stage, a pressure boost energy storage stage, a low-speed injection stage, a high-speed injection stage, a braking stage, a pressure boost stage, a pressure release stage, a tracking stage, and an automatic plunger return stage, which are described below with reference to the drawings.

[0023] During the manual plunger advancement phase, as shown in Figure 2, valves V13, V3, and V9 are energized and open, and the injection cylinder 1 supplies oil to the rodless cavity through the ninth oil passage and then returns oil through the main return oil passage. As can be seen, during the manual plunger advancement phase, the oil pressure pumped by the oil pump to the rodless cavity side of the injection cylinder 1 is large, and in order to make the piston rod of the injection cylinder 1 move slowly and smoothly, the opening of the third servo valve (valve V9) can be controlled to be small at this time, which is beneficial to increasing the pressure at one end of the rod-equipped cavity of the injection cylinder 1, thereby increasing the back pressure on the piston rod of the injection cylinder 1 and making the piston rod move more smoothly.

[0024] 3, in the manual plunger retraction stage, the injection cylinder 1 supplies oil to the rod-equipped cavity through the tenth oil line, and then returns the oil through the eleventh oil line. At this time, the valve V12 is energized, and oil from the oil pump flows into the rod-equipped cavity of the injection cylinder 1 via the valve V12. The valves V3 and V14 are energized, and the oil in the rodless cavity of the injection cylinder 1 is returned to the oil tank. When the oil in the oil pump flows into the rod-equipped cavity of the injection cylinder 1, a large hydraulic pressure is generated in the rod-equipped cavity of the injection cylinder 1. However, because the hydraulic pressure in the rodless cavity of the injection cylinder 1 is small, the operator can easily perform the manual plunger retraction operation, i.e., the plunger return operation, to retract the piston rod in the injection cylinder 1.

[0025] The manual plunger advance operation and manual plunger retraction operation can detect whether the movement of the piston rod in the injection cylinder 1 encounters a large resistance and whether the stroke of the movement is smooth.

[0026] Regarding the injection energy storage stage, as shown in Figure 4, the injection stage is controlled by the fifth oil line. When the injection energy storage stage is performed, the valve V16 is energized and in an open state. At this time, the oil pumped by the oil pump flows into the accumulator 3 through the valve V16 and stores hydraulic energy in the accumulator 3. In addition, in the subsequent work process, the accumulator 3 provides hydraulic pressure for the system, improving the control efficiency and response speed of the system.

[0027] As shown in Figure 5, the boost energy storage stage is controlled by the third and fourth oil lines. During the boost energy storage stage, valve V15 is energized and open. At this time, oil pumped by the oil pump passes through valve V15 and flows into the annular chamber and boost chamber of boost accumulator 2, respectively. That is, after the oil passes through valve V15, the oil line branches to form the third and fourth oil lines. The oil pressure in the third oil line is the same as the oil pressure in the annular chamber of boost accumulator 2, and the oil pressure in the boost chamber of boost accumulator 2 is the same. The oil pressure in the two cavities drives the piston rod in the boost cylinder, thereby creating pressure storage in boost accumulator 2. After the oil pressure storage is completed, valve V15 is closed to maintain sufficient pressure in boost accumulator 2.

[0028] As shown in Figure 6, the low-speed injection stage is controlled by the differential circuit and the first oil passage, and during the low-speed injection stage, valves V3, V4 and V1 are energized and open. At this time, during the injection energy storage stage, hydraulic energy has already been stored in the accumulator 3, so the low-speed start of the injection cylinder 1 can be controlled by the accumulator 3 for oil supply control. The oil in the accumulator 3 flows into the rodless cavity of the injection cylinder 1 through the first oil passage, and on both sides of the piston rod in the injection cylinder 1, the oil action area in the rod-equipped cavity is smaller than that in the rodless cavity. Therefore, during the low-speed injection stage, the oil pressure in the rodless cavity of the injection cylinder 1 is greater than that in the rod-equipped cavity of the injection cylinder 1, and the piston rod of the injection cylinder 1 performs an extension movement, and the first servo valve (valve V4) opens the small opening. By adjusting the opening of the first servo valve, the hydraulic pressure difference between the rodless cavity of the injection cylinder 1 and the rod-equipped cavity of the injection cylinder 1 can be reduced, and pressure buildup can begin. This prevents the pressure in the two cavities from becoming unbalanced, allowing the piston rod of the injection cylinder 1 to extend gradually at a low speed. In this way, the die-casting machine has a smaller starting shock and is more stable during the startup process. This prevents gas from being trapped in the metal liquid inside the cylinder, preventing defects such as air bubbles from occurring in the final die-cast product. It also reduces heat generation due to oil squeezing and reduces oil consumption during the low-speed injection stage.

[0029] As for the high-speed injection stage, as shown in Figure 7, it is controlled by the second oil line, the sixth oil line, and the main return oil line. During the high-speed injection stage, oil pressure is still supplied by the accumulator 3. At this time, valves V1, V3, and the second servo valve (valve V7) are not energized and are in a closed state, while valves V2, V4, V5, V8, and the third servo valve (valve V9) are energized. At this time, the oil inlet of the injection cylinder 1 is fully controlled by valve V2 and is in a fully open state. Specifically, through the second oil line, oil in the accumulator 3 passes through valve V2 and enters the rodless cavity of the injection cylinder 1. Then, through the main return oil line, oil in the rod-equipped cavity of the injection cylinder 1 passes through the third servo valve and enters the oil tank. To achieve faster piston rod movement of the injection cylinder 1, the opening of the third servo valve is adjusted to a larger value at this time, reducing the resistance on the rod-equipped cavity side of the injection cylinder 1 and achieving a faster injection effect of the injection cylinder 1. In addition, through the sixth oil passage, part of the oil in the accumulator 3 passes through the first servo valve (valve V4) and then through valve V8 into the annular chamber of the boost accumulator 2, starting to boost pressure in the boost accumulator 2. Furthermore, because the second servo valve (valve V7) is closed, the oil in the annular chamber of the boost accumulator 2 cannot be discharged, ensuring that the oil in the boost chamber of the boost accumulator 2 does not pass through valve V5 into the rodless cavity of the injection cylinder 1. At this time, valve V5 is opened, and since valve V5 has been opened in advance, when the boost stage begins, simply opening valve V7 directly starts boosting pressure, thereby achieving quick pressure buildup and boosting, and improving response speed.

[0030] As shown in Figure 7, during the braking stage, the control oil path during the braking stage is the same as that during the high-speed injection stage. At this time, hydraulic pressure is still supplied by the accumulator 3. Valves V1, V3, and the second servo valve (valve V7) are not energized and are in a closed state. Valves V2, V4, V5, V8, and the third servo valve (valve V9) are energized. At this time, the oil inlet of the injection cylinder 1 is controlled to be fully open by valve V2. To achieve the deceleration braking of the piston rod of the injection cylinder 1, the opening of the third servo valve (valve V9) is adjusted to adjust the moving speed of the piston rod. Specifically, by reducing the opening of the third servo valve and increasing the resistance at one end of the rod-containing cavity of the injection cylinder 1, the speed of the piston rod of the injection cylinder 1 gradually decreases until it stops moving.

[0031] Regarding the pressure increase stage, as shown in FIG. 8, the pressure increase stage is controlled by the sixth oil line, the seventh oil line, and the eighth oil line. During the pressure increase control stage, the valves V4, V5, V7, and V8 are energized and open. That is, from the braking stage to the pressure increase stage, the third servo valve (valve V9) is closed and the second servo valve (valve V7) is opened, and the valve V5 has already been opened in advance during the high-speed injection stage. At this time, after the second servo valve (valve V7) is opened, the oil in the accumulator 3 flows through valve V4 to valve V8 and then into the annular chamber of the booster accumulator 2. The oil in the annular chamber is discharged through the second servo valve (valve V7) (because the second servo valve is connected to the oil tank and the oil pressure there is low). As the oil pressure in the annular chamber drops, the piston rod in the booster accumulator 2 begins to move, and the oil in the booster chamber begins to discharge and enters the rodless cavity of the injection cylinder 1 through valve V5, thereby boosting the injection cylinder 1 with the booster accumulator 2. The opening of the first servo valve (valve V4) is adjustable, and the opening of the second servo valve (valve V7) is also adjustable. The first and second servo valves form an A-bridge control for the annular chamber of the booster accumulator 2. By controlling the pressure in the annular chamber of the booster accumulator 2, different booster injection force levels can be controlled. Specifically, to reduce the injection force, the opening of the first servo valve or the opening of the second servo valve can be reduced, and to increase the injection force, the opening of the first servo valve or the opening of the second servo valve can be increased.

[0032] In the pressure release stage, as shown in Figure 8, the control oil passage in the pressure release stage and the control oil passage in the pressure increase stage are the same, only the oil supply direction is opposite. In this case, it is only necessary to reduce the pressure in the rodless cavity of the injection cylinder 1, thereby reducing the overall pressure in the injection cylinder 1, and preventing the tracking from becoming uncontrollable due to excessive oil compression in the tracking stage.

[0033] The tracking phase is the operation in which the piston rod of the injection cylinder 1 gradually extends during the mold opening process of the die casting machine. The tracking phase is controlled by the first oil line and the main return oil line. At this time, valves V3, V4, and V9 are energized, and oil in the accumulator 3 flows through the first servo valve (valve V4) into the rodless cavity of the injection cylinder 1. Then, oil in the rod-equipped cavity of the injection cylinder 1 returns to the oil tank through the third servo valve (valve V9). The magnitude of the tracking speed of the die casting machine can be controlled by controlling the opening of valves V4 and V9. Specifically, after the first and third servo valves are controlled to an appropriate opening, the hydraulic pressure in the rodless cavity of the injection cylinder 1 becomes slightly higher than the hydraulic pressure in the rod-equipped cavity of the injection cylinder 1. Thus, during the mold opening operation, the piston rod of the injection cylinder 1 extends the mold, and the speed is maintained relatively stable and gentle.

[0034] During the automatic plunger return phase, after the die-casting machine finishes its work, the mold, the piston rod in the injection cylinder 1, and other structures must all return to their original positions to realize the plunger return operation. Specifically, as shown in Figure 3, the oil path control during the automatic plunger return phase is the same as that during the manual plunger advance phase. The injection cylinder 1 supplies oil to the rod-equipped cavity through oil path 10, and then returns the oil through oil path 11. At this time, valve V12 is energized, allowing oil from the oil pump to enter the rod-equipped cavity of the injection cylinder 1 via valve V12. Valves V3 and V14 are energized, allowing the oil in the rodless cavity of the injection cylinder 1 to be returned to the oil tank. When the oil in the oil pump enters the rod-equipped cavity of the injection cylinder 1, a large hydraulic pressure is generated in the rod-equipped cavity of the injection cylinder 1, but because the hydraulic pressure in the rodless cavity of the injection cylinder 1 is small, the die-casting machine can automatically perform a plunger return operation to retract the piston rod inside the injection cylinder 1. [Explanation of symbols]

[0035] 1 injection cylinder 2. Pressure booster accumulator 3 Accumulator

Claims

1. A die casting machine oil passage system with a dual accumulator, including an injection cylinder and an accumulator, further comprising a pressure boost accumulator and valve assembly; the booster accumulator includes a booster chamber and an annular chamber, the booster chamber communicates with the rodless cavity of the injection cylinder, the accumulator communicates with the annular chamber of the booster accumulator via a first servo valve, the annular chamber communicates with an oil tank via a second servo valve, and the rod-equipped cavity of the injection cylinder communicates with the oil tank via a third servo valve; the valve assembly includes a valve V8 and a valve V5, the accumulator connects the first servo valve and the valve V8 in series to form a sixth oil passage together with the annular chamber of the boost accumulator, the annular chamber of the boost accumulator communicates with the second servo valve to form a seventh oil passage together with the oil tank, the boost chamber of the boost accumulator communicates with the valve V5 to form an eighth oil passage together with the rodless cavity of the injection cylinder, the first servo valve and the second servo valve form an A-bridge control with respect to the annular chamber of the boost accumulator, The valve V5 is an oil supply valve that supplies oil to the rodless cavity of the injection cylinder under pressure booster oil passage control, The valve V8 is an oil supply valve that supplies oil to the annular chamber of the booster accumulator by the accumulator, A differential circuit is formed between the rod-equipped cavity of the injection cylinder and the rodless cavity of the injection cylinder by the first servo valve, and the oil in the accumulator flows into the rodless cavity of the injection cylinder. A die casting machine oil passage system with a dual accumulator.

2. The valve assembly further includes a valve V1 and a valve V3; The valve V1 is a differential valve, The valve V3 is a cartridge valve, the valve V1 and the valve V3 are provided in the differential circuit, The valve V1 is provided on the rod-containing cavity side of the injection cylinder, The valve V3 is provided on the rodless cavity side of the injection cylinder.

2. The die casting machine oil passage system with dual accumulators according to claim 1.

3. The valve assembly further includes a valve V2 that is an active cartridge valve; The accumulator connects the first servo valve and the valve V3 in series to form a first oil passage together with the rodless cavity of the injection cylinder; The accumulator forms a second oil passage together with the rodless cavity of the injection cylinder by the valve V2.

3. The die casting machine oil passage system with dual accumulators according to claim 2.

4. further comprising an oil pump; the valve assembly further includes a valve V15 which is an oil supply valve that supplies oil to the booster chamber and the annular chamber of the booster accumulator by the oil pump; The oil pump forms a third oil passage together with the annular chamber of the booster accumulator by the valve V15, The oil pump forms a fourth oil passage together with the boost chamber of the boost accumulator by the valve V15.

3. The die casting machine oil passage system with dual accumulators according to claim 2.

5. The valve assembly further includes a valve V16; The oil pump forms a fifth oil passage together with the accumulator via the valve V16, The valve V16 is an oil supply valve that supplies oil to the accumulator by an oil pump.

5. The die casting machine oil passage system with dual accumulators according to claim 4.

6. During the high-speed injection phase, The second oil passage allows the oil in the accumulator to pass through the valve V2 and enter the rodless cavity of the injection cylinder, The sixth oil passage allows the oil in the accumulator to further pass through the first servo valve and enter the annular chamber of the booster accumulator.

4. The die casting machine oil passage system with dual accumulators according to claim 3.

7. In the pressure-increasing stage, when the third servo valve is closed and the second servo valve is opened, the oil in the accumulator flows into the annular chamber of the pressure-increasing accumulator, the oil in the annular chamber is discharged by the second servo valve, and the oil in the pressure-increasing chamber flows into the rodless cavity of the injection cylinder.

4. The die casting machine oil passage system with dual accumulators according to claim 3.

8. The valve assembly further includes a valve V13, which is an oil supply valve that supplies oil to the rodless cavity of the injection cylinder by the oil pump; The oil pump sequentially communicates with the valve V13 and the valve V3 to form a ninth oil passage together with the rodless cavity of the injection cylinder.

5. The die casting machine oil passage system with dual accumulators according to claim 4.

9. The valve assembly further includes valve V14 and valve V12; The valve V12 is an oil supply valve that supplies oil to the rod-equipped cavity of the injection cylinder by the oil pump, The valve V14 is an oil return valve that returns oil from the rodless cavity of the injection cylinder to the oil tank. The oil pump communicates the valve V12 with the rod-equipped cavity of the injection cylinder to form a tenth oil passage, The injection cylinder connects the valve V3 and the valve V14 in series to form an eleventh oil passage together with the oil tank.

9. The die casting machine oil passage system with dual accumulators according to claim 8.

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