A shot system of a die-casting machine

Abstract

The present invention discloses a shot system of a die-casting machine, belonging to the technical field of die-casting machine control. It includes an oil cylinder assembly formed by a series connection of a shot cylinder and a boosting cylinder; it also includes an accumulator, and a first servo valve is arranged between the accumulator and the inlet of the oil cylinder assembly, and a second servo valve is arranged at the outlet end of the oil cylinder assembly. During rapid control, the oil in the rod chamber of the shot cylinder returns to the oil tank through the adjustment of the opening of the second servo valve. During boosting control, the oil in the accumulator enters the rod chambers of the shot cylinder and the boosting cylinder respectively through the first servo valve and is discharged through the second servo valve, and the pressure is controlled by the opening ratio of the first servo valve and the second servo valve. This solution uses two servo valves to control the die-casting machine to have the effects of fast speed adjustment during the rapid stage, short pressure build-up time during the boosting stage, and precise control of the shot force.

Description

Technical Field

[0001] The present invention relates to an injection system, and more specifically, to an injection system for a die-casting machine. Background Art

[0002] The speed control of die-casting machines is currently divided into outlet control, inlet control, and combined inlet and outlet control. The disadvantage of outlet control is that during the slow-speed stage, due to the opening of the inlet valve, the sudden compression of the oil in the rod chamber of the injection cylinder causes a starting impact. However, during the high-speed stage, the high-speed speed adjustment is fast, and the acceleration during the acceleration stage is high. The slow-speed start-up section of the inlet control has a small starting impact, but the speed adjustment during the high-speed stage is not as good as that of the outlet control. Although the combined inlet and outlet control has no starting impact during the slow-speed section, when the combined inlet and outlet control is used, since the pressure difference between the two ends of the inlet and outlet valves is smaller than that of the individual inlet and outlet controls, the flow gain at both ends of the valve decreases. Compared with the individual inlet and outlet controls, when the speed changes by the same amount, the spool stroke becomes longer, resulting in a decrease in acceleration during acceleration.

[0003] For the boost control, the current boost pressure control is divided into inlet control, outlet control, B-bridge control, and A-bridge control. The inlet and outlet controls control the amount of oil flowing into the injection cylinder or the amount of oil flowing out of the annular chamber of the boost cylinder through a servo valve to control the amount of oil compression, and thus control the boost injection force. This control method is difficult to control the size of the compression amount, so it is difficult to accurately control the injection force. The principle of B-bridge control is that while the outlet of the annular chamber of the boost cylinder is connected to the servo valve, a thin oil pipe is led from the accumulator and connected to the annular chamber of the boost cylinder. In this way, during boosting, the servo valve first opens to a large opening to quickly build pressure, and then opens to a small opening to control the opening of the outlet, forming two dampings with the thin oil pipe, and controlling the boost injection force by controlling the pressure in the annular chamber. However, in this method, if too much oil in the annular chamber is discharged, when replenishing oil through the thin oil pipe at this time, the speed will be relatively slow, affecting the final boost pressure accuracy. A-bridge control replaces the thin oil pipe in the above B-bridge control with a servo valve, and controls the oil replenishment speed by controlling the opening of the servo valve. The advantage of replacing it with a servo valve is that while ensuring the pressure build-up speed, it can also accurately control the size of the boost injection force, but the cost will be relatively high, and two servo valves are required.

[0004] For example: Chinese Patent Publication No. CN218598493U, publication date March 10, 2023, the name of the utility model is a shot system of a die-casting machine. This application case includes an accumulator and a shot cylinder. A shot cylinder piston rod is slidably arranged in the shot cylinder. The accumulator, the lower chamber of the cartridge valve A4, and the upper chamber of the shot cylinder are connected through pipelines to form a shot circuit; the accumulator, the electromagnetic directional valve A6, and the upper chamber of the cartridge valve A4 are connected through pipelines to form a first oil pressure circuit; the back pressure valve A7, the electromagnetic directional valve A8, the cartridge valve A2, and the lower chamber of the shot cylinder are connected through pipelines to form a second oil pressure circuit; the upper chamber of the shot cylinder is connected to the electromagnetic directional valve A1 through a pipeline and is connected to a first hydraulic oil tank; the lower chamber of the shot cylinder is connected to the cartridge valve A2 through a pipeline and is connected to a first hydraulic oil tank. This shot system of the die-casting machine realizes the control of the speed and pressure of the piston in die-casting, making the speed and pressure of the piston match, ensuring the accuracy of the oil supply pressure and flow rate, and preventing phenomena such as sudden stop and sudden start during die-casting. However, this solution cannot achieve the effects of small starting impact in the slow stage, fast speed adjustment in the fast stage, short pressure build-up time in the boosting stage, and precise control of the shot force of the die-casting machine. Summary of the Invention

[0005] The present invention overcomes the problem of poor control effects of the existing shot system of a die-casting machine on shot speed control and shot pressure, and provides a shot system of a die-casting machine. This solution simultaneously meets the effects of fast speed adjustment in the fast stage, short pressure build-up time in the boosting stage, and precise control of the shot force.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions: A shot system of a die-casting machine includes an oil cylinder assembly formed by a series connection of a shot cylinder and a boosting cylinder; it also includes an accumulator, and a first servo valve is arranged between the accumulator and the inlet of the oil cylinder assembly, and a second servo valve is arranged at the outlet end of the oil cylinder assembly; during fast control, the oil in the accumulator enters the rodless cavity of the shot cylinder through a large-diameter active cartridge valve, and the oil in the rod chamber of the shot cylinder returns to the oil tank through the adjustment of the opening of the second servo valve; during boosting control, the oil in the accumulator enters the rod chambers of the shot cylinder and the boosting cylinder respectively through the first servo valve and is discharged through the second servo valve, and the boosting shot force is adjusted by the opening ratio of the first servo valve and the second servo valve. This solution controls the die-casting machine through two servo valves to have the effects of fast speed adjustment in the fast stage, short pressure build-up time in the boosting stage, and precise control of the shot force; specifically, the first servo valve is a small-diameter servo valve, and the second servo valve is a large-diameter servo valve. By adjusting the opening of the first servo valve and the second servo valve, slow-speed inlet control, fast-speed outlet control, and boosting A-bridge control are realized, achieving smooth speed and no starting impact in the slow stage, large acceleration of speed building in the high-speed stage, multi-stage adjustable speed, large braking acceleration in the braking stage, boosting A-bridge control in the boosting stage, short pressure build-up time in the boosting stage, and precise control of the boosting shot force.

[0007] Preferably, during slow-speed control, the oil in the accumulator forms a differential circuit between the rod chamber and the rodless chamber of the injection cylinder through the first servo valve. Supplied by the accumulator, the oil in the accumulator enters the rodless chamber of the injection cylinder after passing through the first servo valve. The oil in the rod chamber of the injection cylinder can also be replenished to a certain extent into the rodless chamber of the injection cylinder to form a differential circuit. By adjusting the opening of the first servo valve, it is possible to achieve a small starting impact and smooth movement of the piston during the slow-starting stage of the injection cylinder.

[0008] Preferably, it further includes a valve module. The valve module includes valve A3 and valve A6. Valve A6 and valve A3 are located on the differential circuit. Valve A6 communicates with the rod chamber of the injection cylinder, and valve A3 communicates with the rodless chamber of the injection cylinder. The accumulator is sequentially connected in series with the first servo valve and valve A3 and forms a first oil circuit with the rodless chamber of the injection cylinder. Valve A6 is a differential valve that connects the rod chamber and the rodless chamber of the injection cylinder. Valve A3 is an ordinary cartridge valve but needs to have the performance of withstanding high pressure. The oil pressure replenished into the injection cylinder can be regulated by the first servo valve on the first oil circuit to achieve precise control of the oil pressure.

[0009] Preferably, the valve module further includes valve A1. The accumulator communicates with valve A1 and forms a second oil circuit with the rodless chamber of the injection cylinder. Valve A1 is a large-diameter active cartridge valve, and the second oil circuit is the main oil circuit for the accumulator to supply oil to the rodless chamber of the injection cylinder.

[0010] Preferably, the valve module further includes valve A4. The accumulator communicates with valve A4 and forms a third oil circuit with the rodless chamber of the intensifying cylinder. Valve A4 is an intensifying inlet valve, which is the control valve during the braking stage and the intensifying stage. During braking, the opening of the second servo valve is reduced, valve A1 is closed, and valve A4 is opened. The piston rod of the injection cylinder starts to stop moving and enters the intensifying stage.

[0011] Preferably, the valve module further includes valve A9. The accumulator communicates with the first servo valve and forms a fourth oil circuit with the rod chamber of the intensifying cylinder. The accumulator is sequentially connected in series with the first servo valve and valve A9 and forms a fifth oil circuit with the rod chamber of the injection cylinder. Valve A9 is a rod-chamber oil-discharging cartridge valve for the intensifying cylinder. The fourth oil circuit can replenish the oil in the accumulator into the rod chamber of the intensifying cylinder to balance the oil pressure on both sides of the piston rod of the intensifying cylinder. The fifth oil circuit can replenish the oil in the accumulator into the rod chamber of the injection cylinder to balance the oil pressure on both sides of the piston rod of the injection cylinder.

[0012] Preferably, an oil pump is further included. The valve module includes Valve A12, and the output end of the oil pump communicates with Valve A12 and forms an energy storage oil circuit with the accumulator. The oil in the accumulator needs to be replenished by the oil pump at the beginning, so as to maintain the oil pressure energy in the accumulator, ensure that the control of the cylinder assembly can be realized by the oil supply of the accumulator, and improve the control efficiency of the cylinder assembly.

[0013] Preferably, the valve module includes Valve A10, and the output end of the oil pump communicates with Valve A10 and forms the eleventh oil circuit with the rod chamber of the injection cylinder. Valve A10 is the oil inlet valve for the rod chamber of the injection cylinder. By supplying oil to the rod chamber of the injection cylinder through the oil pump, the oil in the rodless chamber of the injection cylinder is returned to the accumulator again, realizing the pressure reduction of the injection cylinder.

[0014] Preferably, the valve module further includes Valve A11. The output end of the oil pump is successively connected in series with Valve A11 and Valve A3 and forms the sixth oil circuit with the rodless chamber of the injection cylinder. Valve A11 is the oil inlet valve for the rodless chamber of the injection cylinder, and the sixth oil circuit is the pre-hammer oil circuit. Before the cylinder assembly officially works, the piston rod of the injection cylinder is slowly extended through the pre-hammer work to ensure the normal movement of the piston rod.

[0015] Preferably, the valve module further includes Valve A5 and Valve A7. The rodless chamber of the injection cylinder communicates with Valve A3 and Valve A5 in sequence and forms the seventh oil circuit with the fuel tank. The rodless chamber of the intensifier cylinder communicates with Valve A7 and forms the eighth oil circuit with the fuel tank. Valve A5 is the return oil cartridge valve for the rodless chamber of the injection cylinder, and Valve A7 is the return oil cartridge valve for the rodless chamber of the intensifier cylinder. The seventh oil circuit is the post-hammer oil circuit, which makes the piston rods of the injection cylinder and the intensifier cylinder slowly retract, realizes the reset operation, and ensures the normal movement of the piston rod.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Only two servo valves are needed to achieve the effects of small starting impact in the slow stage, fast speed adjustment in the fast stage, short pressure building time in the boosting stage, and precise injection force control; (2) The first servo valve is a small-diameter servo valve, and the second servo valve is a large-diameter servo valve. By adjusting the opening ratio of the two valves, the response speed is fast; (3) It has a high-pressure isolation effect, can protect the two servo valves, especially the first servo valve, from damage, and the cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the schematic diagram of the injection oil circuit principle of the present invention.

[0018] Figure 2 It is the schematic diagram of the manual pre-hammer oil circuit of the present invention.

[0019] Figure 3 It is the schematic diagram of the manual or automatic post-hammer oil circuit of the present invention.

[0020] Figure 4 This is the schematic diagram of the oil circuit during the energy storage stage of the present invention.

[0021] Figure 5 This is the schematic diagram of the oil circuit during the slow shot stage of the present invention.

[0022] Figure 6 This is the schematic diagram of the oil circuit during the acceleration stage of the present invention.

[0023] Figure 7 This is the schematic diagram of the oil circuit during the fast shot stage of the present invention.

[0024] Figure 8 This is the schematic diagram of the oil circuit during the braking stage of the present invention.

[0025] Figure 9 This is the schematic diagram of the oil circuit during the boosting stage of the present invention.

[0026] Figure 10 This is the schematic diagram of the oil circuit during the pressure relief stage of the present invention.

[0027] Figure 11 This is the schematic diagram of the oil circuit during the tracking stage of the present invention.

[0028] In the figure: 1. Shot cylinder, 2. Boosting cylinder, 3. Accumulator. Detailed implementation method

[0029] The technical solution of the present invention will be further specifically described below through specific embodiments and in combination with the accompanying drawings.

[0030] Example 1: As Figures 1 to 11 shown, a shot system of a die-casting machine includes an oil cylinder assembly. The oil cylinder assembly includes a shot cylinder 1 and a boosting cylinder 2. The shot cylinder 1 and the boosting cylinder 2 are connected in series. Specifically, the shot cylinder 1 is divided into a rod chamber and a rodless chamber by a piston rod, and the boosting cylinder 2 is also divided into a rod chamber and a rodless chamber by a piston rod. The telescopic end of the piston rod of the shot cylinder 1 is connected to the mold of the die-casting machine, and the telescopic end of the piston rod of the boosting cylinder 2 is connected to the rodless chamber of the shot cylinder 1, so that the shot cylinder 1 and the boosting cylinder 2 are connected in series.

[0031] The shot system of the die-casting machine further includes an accumulator 3, an oil tank, and an oil pump. The accumulator 3 can store hydraulic energy and provide oil for the oil cylinder assembly during the working process of the die-casting machine. The oil pump can supply oil for the entire shot system of the die-casting machine, and the oil tank is the oil return structure for the entire shot system of the die-casting machine.

[0032] As shown in the figure, the injection system of the die-casting machine includes a total of 12 hydraulic valves, namely valves A1 to A12. Among them, valve A1 is a large-diameter active cartridge valve, valve A2 is a small-diameter servo valve, that is, the first servo valve, valve A3 is a common cartridge valve with the characteristic of high-pressure resistance; valve A4 is a cartridge valve for the oil inlet of the rodless cavity of the boosting cylinder 2, valve A5 is a cartridge valve for the oil return of the rodless cavity of the injection cylinder 1, valve A6 is a differential valve, valve A7 is a cartridge valve for the oil return of the rodless cavity of the boosting cylinder 2, valve A8 is a large servo valve for the oil return of the injection cylinder 1, that is, the second servo valve, valve A9 is a cartridge valve for the oil return of the rodless cavity of the boosting cylinder 2, valve A10 is a valve for the oil inlet of the rodless cavity of the injection cylinder 1, valve A11 is a valve for the oil inlet of the rodless cavity of the injection cylinder 1, and valve A12 is an energy storage valve. It should be noted that in this solution, valve A2 is the first servo valve and valve A8 is the second servo valve. The first servo valve has a smaller diameter and the second servo valve has a larger diameter. By adjusting the opening ratio of the first servo valve and the second servo valve, various effects of the cylinder assembly can be controlled to achieve the effects of small start-up impact in the slow stage, fast speed adjustment in the fast stage, short pressure build-up time in the boosting stage, and precise injection force control of the die-casting machine.

[0033] The injection system of the die-casting machine includes multiple oil circuits. Specifically, a differential circuit is formed between the rod chamber and the rodless chamber of the injection cylinder 1. On the differential circuit, a valve A6, a valve A2, and a valve A3 are sequentially connected in series from the rod chamber of the injection cylinder 1 to the rodless chamber of the injection cylinder 1. An accumulator 3 is connected between the valve A6 and the valve A3; the accumulator 3 is sequentially connected in series with the first servo valve (valve A2) and the valve A3, and then connected to the rodless chamber of the injection cylinder 1 to form a first oil circuit. The first oil circuit is the oil circuit for the accumulator 3 to replenish and regulate the oil at one end of the rodless chamber of the injection cylinder 1; the accumulator 3 is sequentially connected in series with the valve A1 and one end of the rodless chamber of the injection cylinder 1 to form a second oil circuit. The second oil circuit is the main oil supply circuit for the accumulator 3 to supply oil to one end of the rodless chamber of the injection cylinder 1. It can be understood that the series oil circuit formed by the valve A2 and the valve A3 is in a parallel structure with the valve A1. The accumulator 3 is sequentially connected in series with the valve A4 and one end of the rodless chamber of the intensifier cylinder 2 to form a third oil circuit. The third oil circuit is the oil circuit for the accumulator 3 to supply oil to the rodless chamber of the intensifier cylinder 2; the accumulator 3 is sequentially connected in series with the first servo valve (valve A2) and one end of the rod chamber of the intensifier cylinder 2 to form a fourth oil circuit. The fourth oil circuit is the oil circuit for the accumulator 3 to supply oil to one end of the rod chamber of the intensifier cylinder 2; the accumulator 3 is sequentially connected in series with the first servo valve (valve A2), the valve A9, and one end of the rod chamber of the injection cylinder 1 to form a fifth oil circuit. The fifth oil circuit is the oil circuit for the accumulator 3 to supply oil to one end of the rod chamber of the injection cylinder 1; the output end of the oil pump is sequentially connected in series with the valve A12 and the accumulator 3 to form an energy storage oil circuit. The energy storage oil circuit is the oil circuit for the oil pump to supply oil to the accumulator 3, enabling the accumulator 3 to store hydraulic energy and ensuring the normal operation of the subsequent die-casting machine; the output end of the oil pump is sequentially connected in series with the valve A10 and one end of the rod chamber of the injection cylinder 1 to form an eleventh oil circuit. The eleventh oil circuit is the oil circuit for the oil pump to supply oil to one end of the rod chamber of the injection cylinder 1, which can enable pressure relief operation in the injection cylinder 1 or enable the piston rod in the injection cylinder 1 to be reset; the output end of the oil pump is sequentially connected in series with the valve A11, the valve A3, and the rodless chamber of the injection cylinder 1 to form a sixth oil circuit. The sixth oil circuit is the oil circuit for the oil pump to supply oil to one end of the rod chamber of the injection cylinder 1; one end of the rodless chamber of the injection cylinder 1 is sequentially connected in series with the valve A3, the valve A5, and the fuel tank to form a seventh oil circuit. The seventh oil circuit is the oil circuit for one end of the rodless chamber of the injection cylinder 1 to return the oil to the fuel tank; one end of the rodless chamber of the intensifier cylinder 2 is sequentially connected to the valve A7 and the fuel tank to form an eighth oil circuit. The eighth oil circuit is the oil circuit for one end of the rodless chamber of the intensifier cylinder 2 to return the oil to the fuel tank. One end of the rod chamber of the injection cylinder 1 is sequentially connected to the second servo valve (valve A8) and the fuel tank to form a ninth oil circuit. The ninth oil circuit is the oil circuit for the oil pressure in the rod chamber of the injection cylinder 1 to return to the fuel tank; one end of the rod chamber of the intensifier cylinder 2 is sequentially connected in series with the valve A9, the second servo valve (valve A8), and the fuel tank to form a tenth oil circuit. The tenth oil circuit is the oil circuit for the oil at one end of the rod chamber of the intensifier cylinder 2 to return to the fuel tank.

[0034] It can be understood that there is only one oil port on both the rod chamber and the rodless chamber of the injection cylinder 1, and there is only one oil port on both the rod chamber and the rodless chamber of the intensifying cylinder 2. Therefore, when the above-mentioned oil circuits are connected to the corresponding cylinders, the oil pipes converge to form a main oil pipe and then connect to the oil port on the injection cylinder 1 or the intensifying cylinder 2.

[0035] The working process of the die-casting machine sequentially includes a manual pre-hammering stage, a manual or automatic post-hammering stage, an energy storage stage, a slow injection stage, an acceleration stage, a fast stage, a braking stage, an intensifying stage, a pressure relief stage, and a tracking stage.

[0036] In the manual pre-hammering stage, as Figure 2 shown, it is controlled by the sixth oil circuit and the ninth oil circuit. The oil pump pumps the oil fluid into the sixth oil circuit, and the oil fluid passes through the valve A11 and the valve A3 in sequence and then enters the rod chamber of the injection cylinder 1. At this time, the valves A10, A12, A9, A5, the first servo valve (valve A2), and the valve A1 are in the closed state. The oil fluid can only enter the rodless chamber side of the injection cylinder 1 through the valve A11 and the valve A3, and pushes the piston rod in the injection cylinder 1 to move outwards. At this time, the valve A6 is in the closed state and the valve A8 is in the open state. The oil fluid in the rod chamber of the injection cylinder 1 returns to the fuel tank through the ninth oil circuit via the valve A8; at this time, the opening degree of the second servo valve (valve A8) can be adjusted to adjust the oil fluid pressures on both sides of the rod chamber and the rodless chamber of the injection cylinder 1, so that the pressure difference between the rod chamber and the rodless chamber of the injection cylinder 1 is reduced. In this way, the staff can manually control the piston rod of the injection cylinder 1 to move out slowly, that is, the manual pre-hammering operation. Through the manual pre-hammering operation, it can be detected whether the piston rod of the injection cylinder 1 moves smoothly during the outward movement.

[0037] It can be understood that in the manual pre-hammering stage, the oil fluid pressure pumped into the rodless chamber side of the injection cylinder 1 by the oil pump is relatively large. In order to make the piston rod of the injection cylinder 1 move slowly and smoothly, the opening degree of the second servo valve (valve A8) can be adjusted to decrease at this time. In this way, it is beneficial to increase the pressure at one end of the rod chamber of the injection cylinder 1, reduce the oil fluid pressure difference on both sides of the piston rod of the injection cylinder 1, and make the piston rod move more smoothly.

[0038] In the manual or automatic post-hammering stage, as Figure 3As shown in the figure, the post-hammering stage is controlled by the seventh oil circuit, the eighth oil circuit, and the eleventh oil circuit. At this time, valves A1, A2, A11, A12, A6, and A8 are all in the closed state. The hydraulic oil in the rodless cavity of the injection cylinder 1 flows back to the fuel tank successively through valves A3 and A5. The hydraulic oil in the rodless cavity of the intensifier cylinder 2 flows back to the fuel tank after passing through valve A7. The oil pump pumps the hydraulic oil into the rod cavity of the injection cylinder 1 and the rod cavity of the intensifier cylinder. Specifically, the hydraulic oil pumped by the oil pump first passes through valve A10, and then a part of the hydraulic oil directly enters the rod cavity of the injection cylinder 1, and another part of the hydraulic oil enters the rod cavity of the intensifier cylinder 2 after passing through valve A9. At this time, since the oil pressure in the rod cavity of the injection cylinder 1 and the rod cavity of the intensifier cylinder 2 is provided by the oil pump, the oil pressure in the rod cavity of the injection cylinder 1 is greater than the oil pressure in the rodless cavity of the injection cylinder 1, and the oil pressure in the rod cavity of the intensifier cylinder 2 is greater than the oil pressure in the rodless cavity of the intensifier cylinder 2. In this way, the piston rods in the injection cylinder 1 and the intensifier cylinder 2 can automatically retract, realizing the automatic post-hammering operation. Of course, when the oil pressure difference on both sides of the piston rods in the injection cylinder 1 and the intensifier cylinder 2 is small, manual post-hammering operation can also be adopted. The post-hammering operation is to slowly retract the piston rods in the injection cylinder 1 and the intensifier cylinder 2 to ensure the smooth reset movement of the piston rods.

[0039] During the energy storage stage, as Figure 4 shown in the figure, the energy storage process of the accumulator is controlled by the energy storage oil circuit. At this time, valves A10, A11, A1, A2, A4, and A6 are all in the closed state. The hydraulic oil pumped by the oil pump can only enter the accumulator 3 through valve A12 and store hydraulic energy in the accumulator 3. And in the subsequent working process, the accumulator 3 is used to provide the oil pressure of the system, improving the control efficiency and response speed of the system.

[0040] During the slow injection stage, as Figure 5 shown in the figure, it is controlled by the differential circuit and the first oil circuit. Since the accumulator 3 has stored hydraulic energy during the energy storage stage, during the slow injection stage, the accumulator 3 can provide power. At this time, at the inlet end of the cylinder assembly, valves A1, A4, and A5 are in the closed state. The hydraulic oil in the accumulator 3 can only enter the rodless cavity of the injection cylinder 1 through the first servo valve (valve A2) and valve A3. At the outlet end of the cylinder assembly, valves A8, A9, and A10 are in the closed state. The hydraulic oil in the rod cavity of the injection cylinder 1 can only flow back to the first oil circuit through valve A6 and then enter the rodless cavity side of the injection cylinder 1 to form a differential circuit.

[0041] It is understandable that on both sides of the piston rod in the injection cylinder 1, the oil acting area in the rod chamber is smaller than the oil acting area in the rodless chamber. Therefore, during the slow injection stage, the oil pressure in the rodless chamber of the injection cylinder 1 is greater than the oil pressure in the rod chamber of the injection cylinder 1, and the piston rod of the injection cylinder 1 moves outwards. And the first servo valve (valve A2) has a small-diameter port. By adjusting the opening degree of the first servo valve, the oil pressure difference between the rodless chamber and the rod chamber of the injection cylinder 1 can be controlled to decrease, and at the same time, pressure building starts, avoiding the situation of unbalanced pressures in the two chambers, so as to realize the slow and steady extension of the piston rod of the injection cylinder 1. In this way, during the start-up process of the die-casting machine, the start-up impact is smaller and it is more stable, avoiding the entrainment of air in the molten metal in the charging cylinder and preventing defects such as bubbles in the final die-cast product.

[0042] Acceleration stage, as Figure 6 shown, is controlled by the first oil circuit, the second oil circuit and the ninth oil circuit. During the slow injection stage, valve A1 is in the closed state, and valve A2 and valve A3 are in the open state. When entering the acceleration stage, open valve A1 and valve A8, and close the second servo valve (valve A2), valve A3 and valve A6. The accumulator 3 transports the oil through the second oil circuit into the rodless chamber of the injection cylinder 1, and the oil in the rod chamber of the injection cylinder 1 flows back to the oil tank through the ninth oil circuit. Since valve A1 is a large-diameter main poppet valve, the oil in the accumulator 3 can be quickly replenished into the rodless chamber of the injection cylinder 1, enabling the piston rod in the injection cylinder 1 to accelerate. During the acceleration process, the acceleration effect can be improved by adjusting the opening degree of the second servo valve (valve A8). Specifically, increase the opening degree of the second servo valve, thereby increasing the oil pressure difference between the rod chamber and the rodless chamber of the injection cylinder 1, so that the speed of the piston rod of the injection cylinder 1 can be quickly adjusted. The acceleration stage lasts for a short time, so that the acceleration stroke of the piston rod of the injection cylinder can be reduced. It should also be noted that at the beginning of the acceleration process, the closing speed of valve A2 and valve A3 is relatively slow, which can form a time-delay closing effect. In this way, during the process of the second oil circuit supplying oil to the rodless chamber of the injection cylinder 1, the first oil circuit can also supply a certain amount of oil to the rodless chamber of the injection cylinder 1, thereby increasing the oil pressure on the rodless chamber side of the injection cylinder 1, further increasing the oil pressure difference on both sides of the injection cylinder 1, and realizing the effect of multi-stage adjustable piston rod speed during the acceleration stage. Since valve A1 does not need to control the stroke of its spool and the spool displacement does not need to be adjusted, valve A1 cooperating with a pilot switch valve with high-frequency response can achieve a shorter full-stroke opening time than the first servo valve, and thus the acceleration will be higher for the inlet and outlet control.

[0043] Fast stage, as Figure 7As shown, after the acceleration stage, valves A2 and A3 are in a fully closed state. The hydraulic oil in the accumulator 3 enters the rodless cavity of the injection cylinder 1 through the second oil circuit, and the hydraulic oil in the rod cavity of the injection cylinder 1 returns to the fuel tank through the ninth oil circuit. By adjusting the opening degree of the second servo valve, the movement speed of the piston rod of the injection cylinder 1 can be controlled, and the final movement speed of the piston rod is formed during the acceleration stage.

[0044] During the braking stage, as Figure 8 shown, it is controlled by the third oil circuit, the second oil circuit and the ninth oil circuit. At the end of the fast stage, the opening degree of the second servo valve (valve A8) is reduced to the boost pre-pressure position, so that the hydraulic oil pressure on the rod cavity side of the injection cylinder 1 increases and approaches the hydraulic oil pressure on the rod cavity side of the injection cylinder 1. The piston rod in the injection cylinder 1 decelerates and brakes; after receiving the closing signal, valve A1 closes directly, and valve A4 opens to prepare for the subsequent boosting stage.

[0045] During the boosting stage, as Figure 9 shown, it is controlled by the third oil circuit, the fourth oil circuit and the fifth oil circuit. The accumulator 3 is located at the inlet end of the cylinder assembly, and the second servo valve is located at the outlet end of the cylinder assembly, thus forming a boost A bridge control. When boosting is required, by adjusting the opening degree ratio of the first servo valve and the second servo valve, the pressures in the rod cavity of the boosting cylinder 2 and the rod cavity of the injection cylinder 1 can be controlled, and then the boost injection force can be controlled. Specifically, the hydraulic oil in the accumulator 3 enters the rodless cavity of the boosting cylinder 2 through valve A4 (the third oil circuit), increasing the hydraulic oil pressure in the rodless cavity of the boosting cylinder 2. Then, the pressure difference on both sides of the piston rod of the boosting cylinder 2 and the pressure difference on both sides of the piston rod of the injection cylinder 1 are balanced through the fourth oil circuit and the fifth oil circuit respectively. Specifically, a part of the hydraulic oil in the accumulator 3 directly enters the rod cavity of the boosting cylinder 2 after passing through the first servo valve. At this time, the hydraulic oil pressure in the rodless cavity of the boosting cylinder 2 is relatively balanced with the hydraulic oil pressure in the rod cavity of the boosting cylinder 2. Another part of the hydraulic oil enters the rod cavity of the injection cylinder 1 after passing through valve A9 to balance the hydraulic oil pressure on both sides of the piston rod of the injection cylinder 1; the excess hydraulic oil pressure returns to the fuel tank through the second servo valve (valve A8). Among them, by increasing the opening degree of the first servo valve and reducing the opening degree of the second servo valve, the overall hydraulic oil pressure of the cylinder assembly can be increased to achieve the boosting effect. It should be noted that in the oil circuit, only valves A1 and A3 bear high pressure as a whole, and neither the first servo valve nor the second servo valve bears high pressure. While reducing the risk of servo valve damage, a larger boost ratio can be designed to increase the pressure in the rodless cavity and thus increase the boost injection force.

[0046] During the pressure relief stage, as Figure 10As shown in the figure, it is controlled by the second oil circuit and the eleventh oil circuit. During this process, the oil pump supplies oil. After going through the aforementioned many working processes, the oil pressure in the accumulator 3 decreases. At this time, valve A1 is opened. After the oil pumped by the oil pump passes through valve A10, it enters the rod chamber of the injection cylinder 1. The oil pressure in the rod chamber of the injection cylinder 1 is greater than the oil pressure in the non-rod chamber of the injection cylinder 1. The piston rod of the injection cylinder 1 starts to retract, and the oil in the non-rod chamber of the injection cylinder 1 is replenished back into the accumulator 3 for pressure relief operation. Moreover, the oil flowing back into the accumulator 3 can be used in the next working cycle. In addition, filling the rod chamber of the injection cylinder 1 with oil can also prevent out-of-control during the tracking stage and avoid damaging the mold or the product. Opening valve A1 can enable the oil pressure in the non-rod chamber of the injection cylinder 1 to quickly flow back into the accumulator 3.

[0047] During the tracking stage, as Figure 11 shown in the figure, the control during the tracking stage is the same as that during the slow injection stage. It is controlled by the differential circuit and the first oil circuit. Since the hydraulic energy has been stored in the accumulator 3 during the pressure relief stage, during the tracking stage, the accumulator 3 can still provide power. At this time, at the inlet end of the cylinder assembly, valves A1, A4, and A5 are in the closed state. The oil in the accumulator 3 can only enter the non-rod chamber of the injection cylinder 1 through the first servo valve (valve A2) and valve A3. At the outlet end of the cylinder assembly, valves A8, A9, and A10 are in the closed state. The oil in the rod chamber of the injection cylinder 1 can only flow back to the first oil circuit through valve A6 and then enter the non-rod chamber side of the injection cylinder 1 to form a differential circuit.

[0048] It can be understood that the acting area of the oil in the rod chamber is smaller than that of the oil in the non-rod chamber on both sides of the piston rod in the injection cylinder 1. Therefore, during the tracking stage, the oil pressure in the non-rod chamber of the injection cylinder 1 is greater than the oil pressure in the non-rod chamber of the injection cylinder 1. The piston rod of the injection cylinder 1 moves outwards. And the first servo valve (valve A2) has a small-diameter port. By adjusting the opening degree of the first servo valve, the oil pressure difference between the non-rod chamber and the rod chamber of the injection cylinder 1 can be controlled to decrease, so as to realize the slow and slow extension of the piston rod of the injection cylinder 1. In this way, during the tracking process of the die-casting machine, the movement of the piston rod is more stable, which can effectively protect the mold and the product.

Claims

1. A shot system of a die-casting machine, comprising a cylinder assembly formed by a series connection of a shot cylinder and a boosting cylinder; characterized in that, It also includes an accumulator, a first servo valve is arranged between the accumulator and the inlet of the oil cylinder assembly, and a second servo valve is arranged at the outlet end of the oil cylinder assembly; During rapid control, the oil in the rod chamber of the injection cylinder returns to the oil tank through the adjustment of the opening of the second servo valve; It also includes a valve module, the valve module includes valve A1, valve A9, valve A3 and valve A4, and the first servo valve forms a parallel structure with valve A1; at the beginning of the acceleration process, the first servo valve forms a delayed closing; The accumulator is connected to the first servo valve and forms a fourth oil circuit with the rod chamber of the intensifier cylinder; the accumulator is sequentially connected in series with the first servo valve and valve A9 and forms a fifth oil circuit with the rod chamber of the injection cylinder; During boosting control, a boosting A-bridge control is formed. The oil in the accumulator enters the rod chambers of the injection cylinder and the intensifier cylinder respectively through the first servo valve, and is discharged through the second servo valve. The oil in the accumulator also enters the rodless chamber of the intensifier cylinder, and the boosting injection force is adjusted by the opening ratio of the first servo valve and the second servo valve; Valve A3 is connected to the rodless chamber of the injection cylinder. The accumulator is sequentially connected in series with the first servo valve and valve A3 and forms a first oil circuit with the rodless chamber of the injection cylinder; the accumulator is connected to valve A4 and forms a third oil circuit with the rodless chamber of the intensifier cylinder.

2. The injection system of a die-casting machine according to claim 1, wherein During slow control, the oil in the accumulator forms a differential circuit between the rod chamber and the rodless chamber of the injection cylinder through the first servo valve.

3. A shot system of a die-casting machine according to claim 2, wherein, The valve module includes valve A6, valve A6 and valve A3 are located on the differential circuit, and valve A6 is connected to the rod chamber of the injection cylinder.

4. The injection system of a die-casting machine according to claim 3, characterized in that The accumulator is connected to valve A1 and forms a second oil circuit with the rodless chamber of the injection cylinder.

5. A shot system of a die casting machine according to claim 3 or 4, characterized in that, The oil in the accumulator enters the rodless chamber of the intensifier cylinder through the third oil circuit, increasing the oil pressure in the rodless chamber of the intensifier cylinder, and then balancing the pressure difference on both sides of the piston rod of the intensifier cylinder and the pressure difference on both sides of the piston rod of the injection cylinder through the fourth oil circuit and the fifth oil circuit respectively.

6. A shot system of a die casting machine according to claim 3 or 4, characterized in that, It also includes an oil pump, the valve module includes valve A12, and the output end of the oil pump is connected to valve A12 and forms an energy storage oil circuit with the accumulator.

7. A shot system of a die-casting machine according to claim 6, characterized in that, The valve module includes valve A10, and the output end of the oil pump is connected to valve A10 and forms an eleventh oil circuit with the rod chamber of the injection cylinder.

8. A shot system of a die-casting machine according to claim 6, characterized in that, The valve module also includes valve A11, and the output end of the oil pump is sequentially connected in series with valve A11 and valve A3 and forms a sixth oil circuit with the rodless chamber of the injection cylinder.

9. The injection system of a die-casting machine according to claim 7, characterized in that, The valve module also includes valve A5 and valve A7. The rodless chamber of the injection cylinder is sequentially connected to valve A3 and valve A5 and forms a seventh oil circuit with the oil tank. The rodless chamber of the intensifier cylinder is connected to valve A7 and forms an eighth oil circuit with the oil tank.

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