Die-casting machine oil passage system with dual accumulators

Abstract

This invention provides a die-casting machine oil passage system with dual accumulators that overcomes the problem of low injection control accuracy in conventional die-casting machines. [Solution] The die-casting machine oil passage system includes an injection cylinder 1 and an accumulator 3, and further includes a pressure boosting accumulator 2, the pressure boosting accumulator includes a pressure boosting chamber and an annular chamber, the pressure boosting chamber communicates with the rodless cavity of the injection cylinder, the accumulator communicates with the annular chamber of the pressure boosting accumulator via a first servo valve, the annular chamber communicates with an oil tank via a second servo valve, and the rod-bearing cavity of the injection cylinder communicates with an oil tank via a third servo valve.

Description

Technical Field

[0001] The present invention relates to a control system of a die-casting machine, and more specifically, to a die-casting machine oil circuit system with a dual accumulator.

Background Art

[0002] For the injection system of a die-casting machine, by using inlet control during low-speed movement, startup shock can be avoided, and by using differential control during low speed, not only can the oil consumption of the accumulator be reduced, but also the oil throttling effect can be reduced and heat generation can be reduced. By using outlet control during high speed, multi-stage adjustment in the high-speed range can be realized, and the flexibility of speed adjustment in the high-speed stage can be improved. By using hydraulic pressure A bridge control in the pressure boosting stage, not only can high-precision adjustment of the pressure boosting injection output be realized, but also stepless adjustment of the pressure boosting injection output can be realized. The die-casting technical means can be customized according to the process. In the prior art, in order to realize the above functions, it is necessary to equip a plurality of servo valves, that is, one for inlet control, one for outlet control, two servo valves for pressure boosting A bridge control, and at least four servo valves.

[0003] For example, in Chinese Patent Publication No. CN118305295A, the title of the invention is "Injection Control Oil Passage, Die Casting Machine and Injection Control Method," and the application discloses a die casting machine control oil passage including a lubrication system, a cartridge valve and a servo valve. The servo valve is connected to the rod cavity of the injection cylinder, and the injection cavity communicates with the rod cavity. When the injection control oil passage is in an outlet throttling state, the cartridge valve is fully open, and the injection speed is controlled by adjusting the opening of the servo valve using a control device. When the injection control oil passage is in an inlet throttling state, the servo valve is fully open, and the injection speed is controlled by adjusting the opening of the cartridge valve using hydraulic fluid. This means that by using the injection control oil passage, the die casting machine can have two speed control methods: outlet throttling and inlet throttling. However, the control accuracy of the die casting machine's injection speed and injection force is not high, and its flexibility is low, making it prone to defects in products formed by die casting. [Overview of the project]

[0004] This 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 technology enables precise control of injection speed and injection force using only three servo valves, thereby improving the injection performance of the die-casting machine.

[0005] To solve the above technical problems, the present invention employs the following technical means. A die-casting machine oil passage system with a dual accumulator includes an injection cylinder and an accumulator, further including a pressure boosting accumulator, the pressure boosting accumulator includes a pressure boosting chamber and an annular chamber, the pressure boosting chamber communicates with a rodless cavity of the injection cylinder, the accumulator communicates with the annular chamber of the pressure boosting accumulator via a first servo valve, the annular chamber communicates with an oil tank via a second servo valve, and the rod-bearing cavity of the injection cylinder communicates with an oil tank via a third servo valve. In this technology, the first and second servo valves form an A-bridge control for the pressure boosting accumulator, thereby controlling the magnitude of the pressure in the annular chamber of the pressure boosting accumulator, and thereby controlling the magnitude of different pressure boosting injection forces of the injection cylinder. The third servo valve can control the discharge oil from the rod cavity of the injection cylinder, thereby controlling the injection speed of the injection cylinder. This technology achieves precise control of injection speed and injection force by using only three servo valves, and can improve the injection performance of the die-casting machine.

[0006] Preferably, a differential circuit is formed between the rod-bearing cavity and the rodless cavity of the injection cylinder by a first servo valve. The differential circuit is formed between the rod-bearing cavity and the rodless cavity of the injection cylinder, and the flow rate of oil in the differential circuit is controlled by the first servo valve, and further, the low-speed injection of the injection cylinder is controlled, thereby reducing and ultimately eliminating the start-up 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 provided in the differential circuit, the valve V1 provided on the rod-bearing cavity side of the injection cylinder, and the valve V3 provided on the rodless cavity side of the injection cylinder. Valve V1 is a differential valve, and in the low-speed injection stage, valves V1, V3 and a first servo valve are energized to form a differential circuit between the rod-bearing cavity and the rodless cavity of the injection cylinder, the oil in the accumulator enters the rodless cavity of the injection cylinder via valves V4 and V3, and the injection speed in the low-speed injection stage can be adjusted by adjusting the opening of the first servo valve, thereby slowing the movement of the piston rod in the injection cylinder.

[0008] Preferably, the valve assembly further includes a valve V2, the accumulator connects the first servo valve and the valve V3 in series in sequence to form a first oil passage together with the rodless cavity of the injection cylinder, and the accumulator, together with the rodless cavity of the injection cylinder by the valve V2, forms a second oil passage. The first oil passage is an oil passage through which the accumulator supplies oil to the rodless cavity of the injection cylinder by the first servo valve, and the second oil passage is the 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, the valve assembly further includes a valve V15, the oil pump forming a third oil passage with the annular chamber of the pressure boosting accumulator by the valve V15, and the oil pump forming a fourth oil passage with the pressure boosting chamber of the pressure boosting accumulator by the valve V15. The third and fourth oil passages allow energy to be stored in the annular chamber and pressure boosting chamber of the pressure boosting accumulator, thereby enabling better pressure boosting control.

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

[0011] Preferably, the valve assembly further includes a valve V8, and the accumulator connects the first servo valve and the valve V8 in series in sequence to form a sixth oil passage together with the annular chamber of the pressure-boosting accumulator. The oil in the accumulator enters the pressure-boosting accumulator via the sixth oil passage, providing sufficient oil for pressure boosting control of the pressure-boosting accumulator and enabling pressure boosting control.

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

[0013] Preferably, the valve assembly further includes a valve V13, and the oil pump connects valve V13 and valve V3 in sequence to form a ninth oil passage together with the rodless cavity of the injection cylinder. The ninth oil passage is supplied with oil by the oil pump, and the oil is introduced into the rodless cavity of the injection cylinder via valves V13 and V3. The oil in the rodded cavity of the injection cylinder is returned to the oil tank via a third servo valve, thereby allowing a manual plunger advance operation to be performed on the die-casting machine before startup.

[0014] Preferably, the valve assembly further includes valves V14 and V12, the oil pump connects valve V12 to the rod-bearing cavity of the injection cylinder to form a 10th oil passage, and the injection cylinder connects valves V3 and V14 in series in sequence to form an 11th oil passage together with the oil tank. The 10th oil passage introduces oil from the oil pump into the rod-bearing cavity of the injection cylinder, and the 11th oil passage introduces oil from the rodless cavity of the injection cylinder into the oil tank, thereby enabling manual or plunger retraction operations on the die-casting machine.

[0015] Compared to conventional technology, the present invention has the following beneficial effects: (1) Precise control of injection speed and injection force can be achieved by using only three servo valves, thereby improving the injection performance of the die-casting machine; (2) The shock when starting up the die-casting machine is reduced, and the movement is smooth; and (3) Multi-stage adjustment in the high-speed range can be achieved by using outlet control in the high-speed stage, thereby improving the flexibility of speed adjustment in the high-speed stage. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram of the oil passage system of the present invention. [Figure 2] This is a schematic diagram of the oil passage during the manual plunger advancement phase of the present invention. [Figure 3] This is a schematic diagram of the oil passages during the manual plunger retraction and automatic plunger return phases of the present invention. [Figure 4] This is a schematic diagram of the oil passage in the injection energy storage stage of the present invention. [Figure 5] This is a schematic diagram of the oil passage in the pressurized energy storage stage of the present invention. [Figure 6] This is a schematic diagram of the oil passage in the low-speed injection stage of the present invention. [Figure 7] This is a schematic diagram of the oil passages in the high-speed injection and braking phases of the present invention. [Figure 8] This is a schematic diagram of the oil passage during the pressure-boosting stage of the present invention. [Figure 9] This is a schematic diagram of the oil passage in the tracking stage of the present invention. [Modes for carrying out the invention]

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

[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 pressure boosting accumulator 2. The accumulator 3 and the pressure boosting accumulator 2 are connected to the oil passage on the rodless cavity inlet side of the injection cylinder 1, and perform inlet control for the injection cylinder 1. The accumulator 3 and the injection accumulator 2 store hydraulic energy and can perform oil control for the injection cylinder 1. Specifically, the pressure boosting accumulator 2 includes a pressure boosting cylinder, the inside of which is a convex cavity, and a piston rod is slidably provided inside the pressure boosting cylinder. The side of the piston rod's rod end away from the piston and the convex end of the pressure boosting cylinder form a pressure boosting chamber, and the side of the piston rod close to the piston's rod end and the pressure boosting cylinder form an annular chamber. The die-casting machine injection oil channel system further includes an oil pump and an oil tank. The oil pump can supply oil to the entire die-casting machine injection oil channel system, and the oil tank is the oil return structure for the entire die-casting machine injection oil channel system.

[0019] As shown in the figure, the die-casting machine injection oil passage system includes a total of 16 hydraulic valves, designated as valves V1 to V16. Valve V1 is a differential valve, valve V2 is a large-diameter active cartridge valve, valve V3 is a general-purpose cartridge valve, valve V3 has high-pressure resistance, valve V4 is the 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 injection cylinder 1 in pressure boosting oil passage control, valves V6, V10 and V11 are safety valves, valves V6, V10 and V11 are normally open hydraulic valves, valve V7 is the second servo valve, the opening of valve V7 is adjustable, and valve V8 is a pressure boosting accumulator 3 Valve V9 is a third servo valve that supplies oil to the annular chamber of accumulator 2, the opening of valve V9 is adjustable, valve V12 is a lubrication valve that supplies oil to the rod cavity of injection cylinder 1 by an oil pump, valve V13 is a lubrication 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 the oil from the rodless cavity of injection cylinder 1 to the oil tank, valve V15 is a lubrication valve that supplies oil to the pressure boosting chamber and annular chamber of pressure boosting accumulator 2 by an oil pump, and valve V16 is a lubrication valve that supplies oil to accumulator 3 by an oil pump. The first and second servo valves form an A-bridge control for the pressure boosting accumulator 2, thereby controlling the magnitude of the pressure in the annular chamber of the pressure boosting accumulator 2, and thereby controlling the magnitude of different pressure boosting injection forces of the injection cylinder 1. The third servo valve can control the discharge oil from the rod-type cavity of the injection cylinder 1, thereby controlling the injection speed of the injection cylinder 1. This technology enables precise control of the injection speed and injection force of a die-casting machine by using only three servo valves, thereby improving the injection performance of the die-casting machine.Valves V6, V10, and V11 remain energized and closed in a non-pressure-release state, thereby providing protection to the oil passage system and facilitating oil draining and maintenance of the oil passage 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 rodded cavity of the injection cylinder 1. The differential circuit is supplied with oil by an accumulator 3, and the accumulator 3 connects valves V1, V4, and V3 in series from the rodded cavity of the injection cylinder 1, forming a differential circuit together with the rodless cavity of the injection cylinder 1. The differential circuit can gradually activate the piston rod in the injection cylinder 1 during the low-speed injection stage, thereby reducing the starting shock. The accumulator 3 connects a first servo valve (valve V4) and valve V3 in series, forming a first oil passage together with the rodless cavity of the injection cylinder 1. As part of the differential circuit, the amount of oil entering the injection cylinder 1 from the accumulator 3 can be adjusted by adjusting the opening of the first servo valve. The accumulator 3 communicates with valve V2 and together with the rodless cavity of the injection cylinder 1 forms a second oil passage, which is the main oil passage that supplies oil to the rodless cavity of the injection cylinder 1 by the accumulator 3. The diameter of valve V2 is large. The oil pump communicates with valve V15 and together with the annular chamber of the pressure-boosting accumulator 2 forms a third oil passage, and the oil pump communicates with valve V15 and together with the pressure-boosting chamber of the pressure-boosting accumulator 2 forms a fourth oil passage. The third and fourth oil passages are oil passages that supply oil to the pressure-boosting accumulator 2 by the oil pump, and the third and fourth oil passages are parallel oil passages so that pressure can be stored and understood in relation to the pressure-boosting accumulator 2. The oil pump communicates with valve V16 and together with the accumulator 3 forms a fifth oil passage, which is an energy storage oil passage that supplies oil to the accumulator 3 by the oil pump. The accumulator 3 connects the first servo valve (valve V4) and valve V8 in series to form a sixth oil passage together with the annular chamber of the pressure-boosting accumulator 2. The sixth oil passage is an oil passage through which the accumulator 3 supplies oil to the pressure-boosting accumulator 2, thereby enabling the pressure-boosting accumulator 3 to provide sufficient hydraulic pressure.The annular chamber of the pressure accumulator 3 communicates with the second servo valve (valve V7) and the oil tank to form the seventh oil passage. The seventh oil passage is the pressure boosting chamber return oil passage of the pressure accumulator 2. Since the opening degree of the second servo valve is adjustable, it is also an oil passage for controlling the injection output of the injection cylinder 1 during pressure boosting control. The pressure boosting chamber of the accumulator 3 forms the eighth oil passage together with the rodless cavity of the injection cylinder 1 after communicating with the valve V5. The eighth oil passage is the pressure boosting oil passage, and the pressure accumulator 2 realizes the pressure boosting effect on the injection cylinder 1. The oil pump connects the valve V13 and the valve V3 in series in sequence to form the ninth oil passage together with the rodless cavity of the injection cylinder. Also, the cavity with a rod of the injection cylinder 1 communicates with the third servo valve (valve V9) and the oil tank to form the main return oil passage. The ninth oil passage and the main return oil passage can gradually extend the piston rod in the injection cylinder 1 and perform a manual plunger forward operation. The oil pump forms the tenth oil passage together with the cavity with a rod of the injection cylinder after communicating with the valve V12. The tenth oil passage is an oil passage for supplying oil to the cavity with a rod of the injection cylinder 1 by the oil pump. The rodless cavity of the injection cylinder 1 forms the eleventh oil passage together with the oil tank after connecting the valve V3 and the valve V14 in series in sequence. The eleventh oil passage is an oil passage for returning oil from the rodless cavity of the injection cylinder 1. The tenth oil passage and the eleventh oil passage can gradually retract the piston rod in the injection cylinder 1 and perform a manual or automatic plunger return operation.

[0021] As can be understood, only one oil port is provided in both the cavity with a rod and the rodless cavity of the injection cylinder 1, and only one oil port is provided in both the pressure boosting chamber and the annular chamber of the pressure accumulator 2. Therefore, when the above oil passages are connected to the corresponding cylinders, the oil pipes merge to form one main oil pipe and then are connected to the oil ports of the injection cylinder 1 or the pressure accumulator 2.

[0022] In this technical means, the working process of the die-casting machine includes, in order, a manual plunger forward stage, a manual plunger backward stage, an injection energy storage stage, a boosting energy storage stage, a low-speed injection stage, a high-speed injection stage, a braking stage, a boosting stage, a pressure release stage, a tracking stage, and an automatic plunger return stage. The following will be described with reference to the drawings.

[0023] In the manual plunger forward stage, as shown in FIG. 2, valves V13, V3, and V9 are energized and in an open state. The injection cylinder 1 supplies oil to the rodless cavity through the ninth oil passage, and then returns the oil through the main return oil passage. As can be understood, in the manual plunger forward stage, the hydraulic pressure pumped by the oil pump to the rodless cavity side of the injection cylinder 1 is large. In order to make the movement of the piston rod of the injection cylinder 1 smooth at a low speed, at this time, the opening degree of the third servo valve (valve V9) can be controlled to be small. In this way, it is advantageous for the boosting at one end of the cavity with a rod in the injection cylinder 1, thereby increasing the back pressure of the piston rod of the injection cylinder 1 and making the movement of the piston rod smoother.

[0024] In the manual plunger backward stage, as shown in FIG. 3, the injection cylinder 1 supplies oil to the cavity with a rod through the tenth oil passage, and then returns the oil through the eleventh oil passage. At this time, valve V12 is energized, and the oil from the oil pump enters the cavity with a rod of the injection cylinder 1 through valve V12. Valves V3 and V14 are energized, and the oil in the rodless cavity of the injection cylinder 1 returns to the oil tank. When the oil in the oil pump enters the cavity with a rod in the injection cylinder 1, a large hydraulic pressure is generated in the cavity with a rod in the injection cylinder 1. However, since the hydraulic pressure on the rodless cavity side of the injection cylinder 1 is small, the operator can easily perform a manual plunger backward operation, that is, a plunger return operation, to retract the piston rod in the injection cylinder 1.

[0025] Manual plunger forward and manual plunger retraction operations can detect whether the movement of the piston rod in the injection cylinder 1 encounters significant resistance, and whether the stroke of that movement is smooth.

[0026] Regarding the injection energy storage stage, as shown in Figure 4, the injection stage is controlled by the fifth oil passage. When the injection energy storage stage is performed, valve V16 is energized and in the open state. At this time, oil pumped by the oil pump enters the accumulator 3 via valve V16, and hydraulic energy is stored in the accumulator 3. Furthermore, in subsequent work processes, the accumulator 3 provides hydraulic pressure to the system, improving the system's control efficiency and response speed.

[0027] Regarding the pressure-boosting energy storage stage, as shown in Figure 5, the pressure-boosting energy storage stage is controlled by the third and fourth oil passages. When in the pressure-boosting energy storage stage, valve V15 is energized and open. At this time, the oil pumped by the oil pump flows through valve V15 and then into the annular chamber and the pressure-boosting chamber of the pressure-boosting accumulator 2, respectively. That is, after the oil passes through valve V15, the oil passage branches, forming the third and fourth oil passages. As a result, the oil pressure in the third oil passage and the oil pressure in the fourth oil passage are the same, the pressure of the oil that has entered the annular chamber of the pressure-boosting accumulator 2 is the same, and the oil pressure in the two cavities moves the piston rod in the pressure-boosting cylinder, creating pressure storage within the pressure-boosting accumulator 2. After the storage of oil pressure is complete, valve V15 is closed to maintain sufficient pressure within the pressure-boosting accumulator 2.

[0028] Regarding the low-speed injection stage, as shown in Figure 6, the low-speed injection stage is controlled by the differential circuit and the first oil passage. When in the low-speed injection stage, valves V3, V4, and V1 are energized and in the open state. At this time, since hydraulic energy is already stored in the accumulator 3 during the injection energy storage stage, the low-speed start of the injection cylinder 1 can be controlled by the accumulator 3. The oil in the accumulator 3 enters the rodless cavity of the injection cylinder 1 via the first oil passage. On both sides of the piston rod in the injection cylinder 1, the area of ​​action of the oil in the rod-bearing cavity is smaller than the area of ​​action of the oil in the rodless cavity. Therefore, in the low-speed injection stage, the hydraulic pressure in the rodless cavity of the injection cylinder 1 is greater than the hydraulic pressure in the rod-bearing cavity of the injection cylinder 1. The piston rod of the injection cylinder 1 extends, and the first servo valve (valve V4) opens. The diameter is through-hole, and by adjusting the opening of the first servo valve, the hydraulic pressure difference between the rodless cavity and the rod-bearing cavity of the injection cylinder 1 can be controlled to be small. At the same time, pressure establishment is initiated and an imbalance in the pressure of the two cavities is avoided, enabling the piston rod of the injection cylinder 1 to extend slowly and gradually. In this way, the die-casting machine has less starting shock and is more stable during the startup process, avoids gas being drawn into the metal liquid that has entered the cylinder, prevents defects such as bubbles from occurring in the final die-cast product, reduces heat generation due to oil throttling, and reduces oil consumption during the low-speed injection stage.

[0029] Regarding the high-speed injection stage, as shown in Figure 7, the high-speed injection stage is controlled by the second oil passage, the sixth oil passage, and the main return oil passage. When in the high-speed injection stage, hydraulic 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 open and completely controlled by valve V2. Specifically, the oil in the accumulator 3 enters the rodless cavity of the injection cylinder 1 via valve V2 through the second oil passage, and then the oil in the rod-bearing cavity of the injection cylinder 1 enters the oil tank via the main return oil passage, passing through the third servo valve. To achieve rapid movement of the piston rod of the injection cylinder 1, the opening of the third servo valve is adjusted to be larger at this time, thereby reducing the resistance on the rod-containing cavity side of the injection cylinder 1 and enabling a rapid injection effect of the injection cylinder 1. In addition, through the sixth oil passage, a portion of the oil in the accumulator 3 enters the annular chamber of the pressure boosting accumulator 2 via the first servo (valve V4) and then via valve V8, and pressure boosting begins in the pressure boosting accumulator 2. Furthermore, because the second servo valve (valve V7) is in the closed state, the oil in the annular chamber of the pressure boosting accumulator 2 cannot be discharged, ensuring that the oil in the pressure boosting chamber of the pressure boosting accumulator 2 does not enter the rodless cavity of the injection cylinder 1 via valve V5. At this time, valve V5 is opened and valve V5 is opened in advance, and when the pressure boosting stage is entered, pressure boosting can be directly performed by simply opening valve V7, thereby achieving rapid pressure establishment and boosting, and improving the response speed.

[0030] Regarding the braking phase, as shown in Figure 7, the control oil passage for the braking phase and the control oil passage for the high-speed injection phase are the same. At this time, hydraulic power 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, 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 controlled to be completely open by valve V2. In order to achieve deceleration braking of the piston rod of the injection cylinder 1, the opening degree of the third servo valve (valve V9) can be adjusted to adjust the movement speed of the piston rod. Specifically, by reducing the opening degree of the third servo valve and increasing the resistance at one end of the rod cavity of the injection cylinder 1, the speed of the piston rod of the injection cylinder 1 is gradually reduced and its movement is stopped.

[0031] Regarding the pressure boosting phase, as shown in Figure 8, the pressure boosting phase is controlled by the 6th, 7th, and 8th oil passages. When in the pressure boosting control phase, valves V4, V5, V7, and V8 are energized and open. That is, from the braking phase to the pressure boosting phase, the 3rd servo valve (valve V9) is closed, the 2nd servo valve (valve V7) is opened, and valve V5 is already open in advance during the high-speed injection phase. At this time, after opening the second servo valve (valve V7), the oil in the accumulator 3 flows to valve V8 via valve V4, and then enters the annular chamber of the pressure boosting accumulator 2. The oil in the annular chamber is discharged via the second servo valve (valve V7) (because the second servo valve communicates with the oil tank and the oil pressure here is low), and as the oil pressure in the annular chamber decreases, the piston rod in the pressure boosting accumulator 2 starts to move, and the oil in the pressure boosting chamber begins to be discharged, enters the rodless cavity of the injection cylinder 1 via valve V5, and the pressure boosting accumulator 2 increases the pressure of the injection cylinder 1. The opening degree of the first servo valve (valve V4) is adjustable, and the opening degree of the second servo valve (valve V7) is adjustable, and the first and second servo valves form an A-bridge control for the annular chamber of the pressure boosting accumulator 2. By controlling the magnitude of the pressure in the annular chamber of the pressure boosting accumulator 2, it is possible to control the magnitude of different pressure boosting injection forces. Specifically, to reduce the injection force, the opening of the first servo valve or the second servo valve can be reduced, and to increase the injection force, the opening of the first servo valve or the second servo valve can be increased.

[0032] Regarding the pressure release phase, as shown in Figure 8, the control oil passage for the pressure release phase and the control oil passage for the pressure boosting phase are the same, with only the direction of oil supply being reversed. At this time, it is sufficient 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 loss of tracking control due to excessive oil compression during the tracking phase.

[0033] Regarding the tracking phase, this phase is the operation in which the piston rod of the injection cylinder 1 gradually extends in accordance with the mold opening process of the die casting machine. The tracking phase is controlled by the first oil passage and the main return oil passage. During this phase, valves V3, V4, and V9 are energized, and the oil in the accumulator 3 enters the rodless cavity of the injection cylinder 1 via the first servo valve (valve V4). Subsequently, the oil in the rod-bearing cavity of the injection cylinder 1 returns to the oil tank via the third servo valve (valve V9). By controlling the opening of valves V4 and V9, the magnitude of the tracking speed of the die casting machine can be controlled. Specifically, after the first and third servo valves are controlled to the appropriate opening, the hydraulic pressure in the rodless cavity of the injection cylinder 1 becomes slightly greater than the hydraulic pressure in the rod-bearing cavity of the injection cylinder 1. In this way, during the mold opening operation, the piston rod of the injection cylinder 1 moves in conjunction with the extension of the mold, and its speed is maintained relatively stably and slowly.

[0034] In the automatic plunger return phase, after the die-casting machine's operation is complete, it is necessary to return all structures, such as the mold and the piston rod inside the injection cylinder 1, to their original positions, thereby enabling the plunger return operation. Specifically, as shown in Figure 3, the oil passage control in the automatic plunger return phase and the oil passage control in the manual plunger advance phase are the same. The injection cylinder 1 supplies oil to the rod cavity via the 10th oil passage, and then returns the oil via the 11th oil passage. At this time, valve V12 is energized, and oil from the oil pump enters the rod cavity of the injection cylinder 1 via valve V12. Valves V3 and V14 are also energized, and the oil in the rodless cavity of the injection cylinder 1 is returned to the oil tank. When oil from the oil pump enters the rod cavity of injection cylinder 1, a large hydraulic pressure is generated within the rod cavity of injection cylinder 1. However, because the hydraulic pressure on the rodless cavity side of injection cylinder 1 is small, the die-casting machine can automatically perform a plunger return operation to retract the piston rod inside injection cylinder 1. [Explanation of symbols]

[0035] 1. Injection cylinder 2. Pressure-boosting accumulator 3. Accumulator

Claims

1. A die-casting machine oil passage system with a dual accumulator, including an injection cylinder and an accumulator, Further including a pressure boosting accumulator and valve assembly, The pressure boosting accumulator includes a pressure boosting chamber and an annular chamber, the pressure boosting chamber communicates with the rodless cavity of the injection cylinder, the accumulator communicates with the annular chamber of the pressure boosting accumulator via a first servo valve, the annular chamber communicates with an oil tank via a second servo valve, and the rod-bearing cavity of the injection cylinder communicates with an oil tank via a third servo valve. The valve assembly includes valve V8 and valve V5, the accumulator connects the first servo valve and valve V8 in series in sequence to form a sixth oil passage together with the annular chamber of the pressure boosting accumulator, the annular chamber of the pressure boosting accumulator communicates with the second servo valve to form a seventh oil passage together with the oil tank, the pressure boosting chamber of the pressure boosting accumulator communicates with 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 pressure boosting accumulator. The valve V5 is an oil supply valve that supplies oil to the rodless cavity of the injection cylinder in the pressure boosting oil passage control. The valve V8 is an oil supply valve that supplies oil to the annular chamber of the pressure boosting accumulator by the accumulator. A die-casting machine oil passage system with dual accumulators, characterized by the following features.

2. A differential circuit is formed between the rod-bearing cavity of the injection cylinder and the rodless cavity of the injection cylinder by the first servo valve, and the oil liquid in the accumulator enters the rodless cavity of the injection cylinder. The die-casting machine oil passage system with dual accumulators as described in claim 1.

3. The valve assembly further includes valve V1 and valve V3, The valve V1 is a differential valve, The aforementioned valve V3 is a cartridge valve, The valves V1 and 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. The die-casting machine oil passage system with dual accumulators according to feature 2.

4. The valve assembly further includes a valve V2 which is an active cartridge valve, The accumulator connects the first servo valve and the valve V3 in series in order to form a first oil passage together with the rodless cavity of the injection cylinder. The accumulator, together with the rodless cavity of the injection cylinder, forms a second oil passage through the valve V2. The die-casting machine oil passage system with dual accumulators as described in claim 3.

5. It further includes an oil pump, The valve assembly further includes a valve V15, which is an oil supply valve that supplies oil to the pressure boosting chamber and the annular chamber of the pressure boosting accumulator by the oil pump. The oil pump, together with the annular chamber of the pressure boosting accumulator, forms a third oil passage through the valve V15. The oil pump, together with the pressure-boosting chamber of the pressure-boosting accumulator, forms a fourth oil passage with the valve V15. A die-casting machine oil passage system with a dual accumulator as described in claim 3 or 4.

6. The valve assembly further includes valve V16, The oil pump, together with the accumulator, forms a fifth oil passage with the valve V16. The valve V16 is an oil supply valve that supplies oil to the accumulator by an oil pump. The die-casting machine oil passage system with dual accumulators according to feature 5.

7. During the high-speed injection phase, Through the second oil passage, the oil in the accumulator enters the rodless cavity of the injection cylinder via the valve V2. Through the sixth oil passage, the oil in the accumulator further enters the annular chamber of the pressure boosting accumulator via the first servo valve. The die-casting machine oil passage system with dual accumulators as described in feature 4.

8. During the pressure-boosting phase, when the third servo valve is closed and the second servo valve is opened, the oil in the accumulator enters the annular chamber of the pressure-boosting accumulator, the oil in the annular chamber is discharged by the second servo valve, and the oil in the pressure-boosting chamber enters the rodless cavity of the injection cylinder. A die-casting machine oil passage system with a dual accumulator as described in 4 or 7.

9. 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 connects valve V13 and valve V3 in sequence to form a ninth oil passage together with the rodless cavity of the injection cylinder. The die-casting machine oil passage system with dual accumulators according to feature 5.

10. The valve assembly further includes valve V14 and valve V12, The valve V12 is an oil supply valve that supplies oil to the rod cavity of the injection cylinder by the oil pump. The valve V14 is an oil return valve that returns the oil from the rodless cavity of the injection cylinder back to the oil tank. The oil pump connects the valve V12 and the rod cavity of the injection cylinder to form a tenth oil passage. The injection cylinder connects valve V3 and valve V14 in series in sequence to form an 11th oil passage together with the oil tank. The die-casting machine oil passage system with dual accumulators as described in feature 9.

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