Injection system of die-casting machine

Abstract

The invention discloses an injection system of a die-casting machine, which belongs to the technical field of die-casting machine control and comprises an oil cylinder assembly formed by an injection oil cylinder and a pressurizing oil cylinder which are connected in series. The hydraulic system further comprises an energy accumulator, a first servo valve is arranged between the energy accumulator and an 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, oil in a rod cavity of the injection oil cylinder flows back to the oil tank through the opening degree adjustment of the second servo valve; during pressurization control, oil in the energy accumulator enters rod cavities of the injection oil cylinder and the pressurization oil cylinder through the first servo valve and is discharged through the second servo valve, and the pressure is controlled through the opening degree proportion of the first servo valve and the second servo valve. According to the scheme, the two servo valves are used for controlling the die-casting machine to have the effects of being high in speed adjustment speed in the rapid stage, short in pressure building time in the pressurization stage and accurate in injection force control.

Description

Technical Field

[0001] The present invention relates to an injection system, and more particularly to an injection system of 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 in the slow stage, due to the opening of the inlet valve, the oil in the rod chamber of the injection cylinder is suddenly compressed, causing starting shock, but in the high-speed stage, the high-speed speed is adjusted quickly, and the acceleration stage is high. The slow start-up shock of inlet control is small, but the speed adjustment in the high-speed stage is not as good as that of outlet control. Although there is no starting shock in the slow stage of combined inlet and outlet control, the pressure difference between the two ends of the inlet and outlet valve is less than that of the single inlet and outlet control during combined inlet and outlet control, resulting in a decrease in the flow gain at both ends of the valve. Compared with the single inlet and outlet control, when the same speed changes, the valve core stroke becomes longer, resulting in a decrease in acceleration during acceleration.

[0003] For 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 control is to control the inflow of the injection cylinder oil through the servo valve or control the outflow of the annular cavity of the boost cylinder oil to control the compression of the oil, and then control the boost pressure injection force. This control method is difficult to control the size of the compression, so the injection force is difficult to control accurately. The principle of B-bridge control is that while the annular cavity outlet of the boost cylinder is connected to the servo valve, a thin oil pipe is drawn from the accumulator and connected to the annular cavity of the boost cylinder. In this way, when boosting, the servo valve first opens a large degree to quickly build pressure, and then opens a small degree to control the opening of the outlet, forming two dampings with the thin oil pipe, and controlling the annular cavity pressure to control the boost pressure injection force. However, if the annular cavity oil is discharged too much, the speed of replenishing oil through the thin oil pipe will be relatively slow, affecting the final boost pressure accuracy. The A-bridge control replaces the thin oil pipe in the above-mentioned 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 it can accurately control the size of the boost pressure while ensuring the pressure building speed. However, the cost will be relatively high, and two servo valves are required.

[0004] For example: Chinese patent announcement number CN218598493U, announcement date March 10, 2023, the name of the utility model is a die-casting machine injection system, the application includes an accumulator and an injection cylinder, the injection cylinder piston rod is slidably arranged in the injection cylinder, the accumulator, the lower chamber of the cartridge valve A4 and the upper chamber of the injection cylinder are connected by a pipeline to form an injection circuit; the accumulator, the electromagnetic reversing valve A6 and the upper chamber of the cartridge valve A4 are connected by a pipeline to form a first oil pressure circuit; the back pressure valve A7, the electromagnetic reversing valve A8, the cartridge valve A2 and the lower chamber of the injection cylinder are connected by a pipeline to form a second oil pressure circuit; the upper chamber of the injection cylinder is connected to the electromagnetic reversing valve A1 through a pipeline and is connected to a first hydraulic oil tank; the lower chamber of the injection cylinder is connected to the cartridge valve A2 through a pipeline and is connected to the first hydraulic oil tank. The die-casting machine injection system realizes the control of the speed and pressure of the die-casting piston, so that the speed and pressure of the piston are matched, ensuring the accuracy of the oil supply pressure and flow, and preventing sudden stops and starts during die-casting. However, this solution cannot achieve the effect of small start-up impact of the die-casting machine in the slow stage, fast speed adjustment in the fast stage, short pressure build-up time in the boost stage, and precise injection force control. Summary of the invention

[0005] The present invention overcomes the problem that the existing die-casting machine injection system has poor control effect on injection speed and injection pressure, and provides a die-casting machine injection system. This solution simultaneously meets the effects of fast speed adjustment in the rapid stage, short pressure building time in the boost stage and precise injection force control.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: a die-casting machine injection system, including a cylinder assembly formed by an injection cylinder and a booster cylinder connected in series; also including an accumulator, a first servo valve is arranged between the accumulator and the inlet of the cylinder assembly, and a second servo valve is arranged at the outlet end of the cylinder assembly; during rapid control, the accumulator oil enters the rodless chamber of the injection cylinder through a large-diameter active cartridge valve, and the oil in the rod chamber of the injection cylinder flows back to the oil tank through the adjustment of the opening of the second servo valve; during boost control, the oil in the accumulator enters the rod chambers of the injection cylinder and the booster cylinder respectively through the first servo valve, and is discharged through the second servo valve, and the booster injection force is adjusted 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 in the fast stage, short pressure building time and precise injection force control in the boost stage; 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 inlet control, fast outlet control and boost A-bridge control are realized, so that the speed in the slow stage is stable and there is no starting impact, the high-speed stage has a large acceleration in speed building, the speed can be adjusted in multiple stages, the braking stage has a large braking acceleration, the boost stage has A-bridge control, the boost pressure building time is short, and the boost injection force control is precise.

[0007] As a preferred embodiment, during slow control, the oil in the accumulator forms a differential circuit between the rod chamber of the injection oil cylinder and the rodless chamber of the injection oil cylinder through the first servo valve. The oil is supplied by the accumulator, and the oil in the accumulator enters the rodless chamber of the injection oil cylinder after passing through the first servo valve. At the same time, the oil in the rod chamber of the injection oil cylinder can also be replenished to a certain extent into the rodless chamber of the injection oil cylinder to form a differential circuit. By adjusting the opening of the first servo valve, the piston of the injection oil cylinder can be started with a small impact and a smooth movement during the slow start stage.

[0008] Preferably, a valve module is further included, the valve module includes valve A3 and valve A6, the valve A6 and valve A3 are located on the differential circuit, the valve A6 is connected to the rod chamber of the injection oil cylinder, the valve A3 is connected to the rodless chamber of the injection oil cylinder, the accumulator is connected in series with the first servo valve and the valve A3 in sequence and forms a first oil circuit with the rodless chamber of the injection oil cylinder. Valve A6 is a differential valve, connecting the rod chamber of the injection oil cylinder and the rodless chamber of the injection oil cylinder, valve A3 is an ordinary cartridge valve, but it needs to have high pressure resistance; the first servo valve on the first oil circuit can regulate the oil pressure added to the injection oil cylinder to achieve precise control of the oil pressure.

[0009] Preferably, the valve module further comprises a valve A1, the accumulator is connected to the valve A1 and forms a second oil circuit with the rodless chamber of the injection cylinder. The 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 comprises a valve A4, the accumulator is connected to the valve A4 and forms a third oil circuit with the rodless chamber of the boosting oil cylinder. Valve A4 is a boosting inlet valve and a control valve for the braking stage and the boosting stage. When braking, the opening of the second servo valve is reduced, valve A1 is closed, valve A4 is opened, the piston rod of the injection oil cylinder begins to stop moving, and enters the boosting stage.

[0011] Preferably, the valve module further comprises a valve A9, the accumulator is connected to the first servo valve and forms a fourth oil circuit with the rod chamber of the boosting oil cylinder, the accumulator is connected in series with the first servo valve and valve A9 in sequence and forms a fifth oil circuit with the rod chamber of the injection oil cylinder. Valve A9 is a boosting oil cylinder rod chamber oil discharge cartridge valve, the fourth oil circuit can replenish the oil in the accumulator into the rod chamber of the boosting oil cylinder to balance the oil pressure on both sides of the boosting oil cylinder piston rod, and the fifth oil circuit can replenish the oil in the accumulator into the rod chamber of the injection oil cylinder to balance the oil pressure on both sides of the injection oil cylinder piston rod.

[0012] Preferably, an oil pump is further included, and the valve module includes a valve A12. The output end of the oil pump is connected to the 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 that the oil pressure energy is maintained in the accumulator, ensuring that the control of the cylinder assembly can be achieved through the oil supply of the accumulator, thereby improving the control efficiency of the cylinder assembly.

[0013] Preferably, the valve module includes a valve A10, and the output end of the oil pump is connected to the valve A10 and forms an eleventh oil circuit with the rod chamber of the injection oil cylinder. Valve A10 is an oil inlet valve for the rod chamber of the injection oil cylinder, and supplies oil to the rod chamber of the injection oil cylinder through the oil pump, and returns the oil in the rodless chamber of the injection oil cylinder to the accumulator, thereby reducing the pressure of the injection oil cylinder.

[0014] Preferably, the valve module further comprises a valve A11, and the output end of the oil pump is connected in series with the valve A11 and the valve A3 in sequence and forms a sixth oil circuit with the rodless chamber of the injection oil cylinder. Valve A11 is an oil inlet valve for the rodless chamber of the injection oil cylinder, and the sixth oil circuit is a pre-hammer oil circuit. Before the oil cylinder assembly officially works, the piston rod of the injection oil cylinder is slowly extended through the pre-hammer work to ensure that the piston rod can move normally.

[0015] Preferably, the valve module further comprises valve A5 and valve A7, the rodless chamber of the injection oil cylinder is connected to valve A3 and valve A5 in sequence and forms a seventh oil circuit with the oil tank, and the rodless chamber of the boost oil cylinder is connected to valve A7 and forms an eighth circuit with the oil tank. Valve A5 is a rodless chamber oil return cartridge valve for the injection oil cylinder, valve A7 is a rodless chamber oil return cartridge valve for the boost oil cylinder, and the seventh oil circuit is a post-hammer oil circuit, so that the piston rods of the injection oil cylinder and the boost oil cylinder are slowly retracted to achieve a reset operation and ensure that the piston rods can move normally.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) only two servo valves are needed 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 boost 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, which can protect the two servo valves, especially the first servo valve, from damage, and reduce the cost. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0019] Figure 3 It is a schematic diagram of the oil circuit after manual or automatic hammering of the present invention.

[0020] Figure 4 It is a schematic diagram of the oil circuit in the energy storage stage of the present invention.

[0021] Figure 5 It is a schematic diagram of the oil circuit in the slow injection stage of the present invention.

[0022] Figure 6 It is a schematic diagram of the oil circuit in the acceleration stage of the present invention.

[0023] Figure 7 This is a schematic diagram of the oil circuit in the rapid stage of the present invention.

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

[0025] Fig. 9 It is a schematic diagram of the oil circuit in the boost stage of the present invention.

[0026] Fig.10 It is a schematic diagram of the oil circuit in the pressure relief stage of the present invention.

[0027] Fig.11 This is a schematic diagram of the oil circuit in the tracking stage of the present invention.

[0028] In the figure: 1. Injection cylinder, 2. Booster cylinder, 3. Accumulator. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

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

[0031] The die-casting machine injection system also includes an accumulator 3, an oil tank and an oil pump. The accumulator 3 can store hydraulic energy and provide oil to the cylinder assembly during the operation of the die-casting machine. The oil pump can supply oil to the entire die-casting machine injection system, and the oil tank is the oil return structure of the entire die-casting machine injection system.

[0032] As shown in the figure, the die-casting machine injection system includes 12 hydraulic valves, namely valve A1 to valve 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 characteristics of high pressure resistance; valve A4 is a rodless chamber oil inlet cartridge valve for booster cylinder 2, valve A5 is a rodless chamber oil return cartridge valve for injection cylinder 1, valve A6 is a differential valve, valve A7 is a rodless chamber oil return cartridge valve for booster cylinder 2, valve A8 is a large servo valve for injection cylinder 1 oil return, that is, the second servo valve, valve A9 is a rod chamber oil return cartridge valve for booster cylinder 2, valve A10 is a rod chamber oil inlet valve for injection cylinder 1, valve A11 is a rodless chamber oil inlet valve for injection cylinder 1, and valve A12 is an energy storage valve. It should be noted that, in the present solution, valve A2 is the first servo valve, 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, the various effects of the cylinder assembly can be controlled to achieve the effect that the die-casting machine has a small start-up impact in the slow stage, fast speed adjustment in the fast stage, short pressure build-up time in the boost stage, and precise control of the injection force.

[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 oil cylinder 1. On the differential circuit, valves A6, A2, and A3 are connected in series from the rod chamber of the injection oil cylinder 1 to the rodless chamber of the injection oil cylinder 1. An accumulator 3 is connected between valves A6 and A3. The accumulator 3 is connected in series with the first servo valve (valve A2) and valve A3 in sequence, and then connected to the rodless chamber of the injection oil cylinder 1 to form the first oil circuit. The first oil circuit is the oil circuit for the accumulator 3 to adjust the oil replenishment for one end of the rodless chamber of the injection oil cylinder 1. The accumulator 3 is connected in series with valve A1 and one end of the rodless chamber of the injection oil cylinder 1 in sequence to form the second oil circuit. The second oil circuit is the oil circuit for the accumulator 3 to mainly supply oil to one end of the rodless chamber of the injection oil cylinder 1. It can be understood that the series oil circuit formed by valves A2 and A3 forms a parallel structure with valve A1. The accumulator 3 is connected in series with valve A4 and one end of the rodless chamber of the boosting cylinder 2 in sequence to form a third oil circuit, and the third oil circuit is the oil circuit for the accumulator 3 to supply oil to the rodless chamber of the boosting cylinder 2; the accumulator 3 is connected in series with the first servo valve (valve A2) and one end of the rod chamber of the boosting cylinder 2 in sequence to form a fourth oil circuit, and the fourth oil circuit is the oil circuit for the accumulator 3 to supply oil to one end of the rod chamber of the boosting cylinder 2; the accumulator 3 is connected in series with the first servo valve (valve A2), valve A9 and one end of the rod chamber of the injection cylinder 1 in sequence to form a fifth oil circuit, and 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 connected in series with valve A12 and accumulator 3 in sequence to form an energy storage oil circuit, and the energy storage oil circuit is the oil circuit for the oil pump to provide oil to the accumulator 3, so that the accumulator 3 stores hydraulic energy to ensure the normal operation of the subsequent die-casting machine; the output end of the oil pump is connected in series with valve A12 and accumulator 3 in sequence to form an energy storage oil circuit. The connecting valve A10 and one end of the rod chamber of the injection cylinder 1 form an eleventh oil circuit, which is an oil circuit for the oil pump to supply oil to one end of the rod chamber of the injection cylinder 1, which can enable the injection cylinder 1 to perform a pressure relief operation or a reset operation of the piston rod in the injection cylinder 1; the output end of the oil pump is connected in series with valve A11, valve A3 and the rodless chamber of the injection cylinder 1 in sequence to form a sixth oil circuit, which is an 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 connected in series with valve A3, valve A5 and the oil tank in sequence to form a seventh oil circuit, which is an oil circuit for the rodless chamber of the injection cylinder 1 to return oil to the oil tank; one end of the rodless chamber of the booster cylinder 2 is connected in series with valve A7 and the oil tank to form an eighth oil circuit, which is an oil circuit for the rodless chamber of the booster cylinder 2 to return oil to the oil tank. One end of the rod chamber of the injection cylinder 1 is connected in series with the second servo valve (valve A8) and the oil tank to form the ninth oil circuit, and the ninth oil circuit is the oil circuit for the oil pressure in the rod chamber of the injection cylinder 1 to flow back to the oil tank; one end of the rod chamber of the booster cylinder 2 is connected in series with valve A9, the second servo valve (valve A8) and the oil tank to form the tenth oil circuit, and the tenth oil circuit is the oil circuit for the oil at one end of the rod chamber of the booster cylinder 2 to flow back to the oil tank.

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

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

[0036] Manual hammer pre-stage, such as Figure 2 As shown, the oil pump is controlled by the sixth oil circuit and the ninth oil circuit to pump the oil into the sixth oil circuit. The oil passes through valve A11 and valve A3 in sequence and then enters the rod chamber of the injection cylinder 1. At this time, valve A10, valve A12, valve A9, valve A5, the first servo valve (valve A2) and valve A1 are in a closed state. The oil can only enter the rodless chamber side of the injection cylinder 1 through valve A11 and valve A3, and push the piston rod in the injection cylinder 1 to extend. At this time, valve A6 is closed and valve A8 is open. , the oil in the rod chamber of the injection oil cylinder 1 flows back to the oil tank through the ninth oil path and the valve A8; at this time, the oil pressure on both sides of the rod chamber and the rodless chamber of the injection oil cylinder 1 can be adjusted by adjusting the opening of the second servo valve (valve A8), so that the pressure difference between the rod chamber and the rodless chamber of the injection oil cylinder 1 is reduced, so that the staff can manually control the piston rod of the injection oil cylinder 1 to extend slowly, that is, the manual hammer-front operation, through which it can be detected whether the piston rod of the injection oil cylinder 1 is smooth when extending.

[0037] It is understandable that in the pre-manual hammer stage, the oil pressure pumped into the rodless chamber side of the injection cylinder 1 by the oil pump is relatively high. In order to make the piston rod of the injection cylinder 1 move slowly and smoothly, the opening of the second servo valve (valve A8) can be adjusted to decrease at this time. This is conducive to pressurizing the rod chamber end of the injection cylinder 1, reducing the oil pressure difference on both sides of the piston rod of the injection cylinder 1, and making the piston rod move more smoothly.

[0038] Manual or automatic post-hammer stage, such as Figure 3As shown, the post-hammer stage is controlled by the seventh oil circuit, the eighth oil circuit and the eleventh oil circuit. At this time, valve A1, valve A2, valve A11, valve A12, valve A6 and valve A8 are all in a closed state, and the oil in the rodless chamber of the injection cylinder 1 flows back to the oil tank through valve A3 and valve A5 in turn, and the oil in the rodless chamber of the booster cylinder 2 flows back to the oil tank after passing through valve A7; the oil pump pumps the oil into the rod chamber of the injection cylinder 1 and the rod chamber of the booster cylinder. Specifically, the oil pumped in by the oil pump first passes through valve A10, and then a part of the oil directly enters the rod chamber of the injection cylinder 1, and there is also A part of the oil enters the rod chamber of the booster cylinder 2 after passing through valve A9; at this time, since the oil pressure in the rod chamber of the injection cylinder 1 and the rod chamber of the booster cylinder 2 is provided by the oil pump, the oil pressure in the rod chamber of the injection cylinder 1 is greater than the oil pressure in the rodless chamber of the injection cylinder 1, and the oil pressure in the rod chamber of the booster cylinder 2 is greater than the oil pressure in the rodless chamber of the booster cylinder 2, so that the piston rods in the injection cylinder 1 and the booster cylinder 2 can be automatically retracted to achieve automatic post-hammer operation. Of course, when the oil pressure difference on both sides of the piston rods of the injection cylinder 1 and the booster cylinder 2 is small, manual post-hammer operation can also be used. The post-hammer operation is to slowly retract the piston rods in the injection cylinder 1 and the booster cylinder 2 to ensure smooth reset movement of the piston rods.

[0039] Energy storage stage, such as Figure 4 As shown, the energy storage process of the accumulator is controlled by the energy storage oil circuit. At this time, valve A10, valve A11, valve A1, valve A2, valve A4 and valve A6 are all in a closed state, and the oil pumped by the oil pump can only enter the accumulator 3 through valve A12, and store hydraulic energy in the accumulator 3. In the subsequent working process, the oil pressure of the system is provided by the accumulator 3 to improve the control efficiency and response speed of the system.

[0040] Slow injection stage, such as Figure 5 As shown, it is controlled by the differential circuit and the first oil circuit. Since hydraulic energy has been stored in the accumulator 3 during the energy storage stage, the accumulator 3 can provide power during the slow injection stage. At this time, at the inlet end of the cylinder assembly, valves A1, A4 and A5 are in a closed state, and the 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 a closed state, and the 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 can be understood that, on both sides of the piston rod in the injection cylinder 1, the oil action area in the rod chamber is smaller than the oil action area in the rodless chamber. Therefore, in 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 extends. In addition, the first servo valve (valve A2) is a small-diameter port. By adjusting the opening of the first servo valve, the oil pressure difference between the rodless chamber of the injection cylinder 1 and the rod chamber of the injection cylinder 1 can be controlled to decrease, and pressure can be built up at the same time to avoid imbalance in the pressure of the two chambers, thereby achieving slow extension of the piston rod of the injection cylinder 1. In this way, the die-casting machine has a smaller starting impact and is more stable during startup, which avoids air entrainment of the molten metal in the feed barrel and prevents defects such as bubbles in the final die-casting product.

[0042] The acceleration phase, such as Figure 6 As shown, it is controlled by the first oil circuit, the second oil circuit and the ninth oil circuit. In the slow injection stage, valve A1 is in a closed state, valve A2 and valve A3 are in an open state. When entering the acceleration stage, valves A1 and A8 are opened, and the second servo valve (valve A2), valve A3 and valve A6 are closed. The accumulator 3 delivers the oil to the rodless chamber of the injection cylinder 1 through the second oil circuit, 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 active cartridge valve, the oil in the accumulator 3 can be quickly replenished to the rodless chamber of the injection cylinder 1, so that the piston rod in the injection cylinder 1 accelerates. During the acceleration process, the acceleration effect can be improved by adjusting the opening of the second servo valve (valve A8). Specifically, the opening of the second servo valve is increased, thereby increasing the oil pressure difference between the rod chamber and the rodless chamber of the injection cylinder 1, so that the piston rod speed of the injection cylinder 1 can be quickly adjusted. The acceleration phase lasts for a short time, so 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 slow, which can form a delayed closing effect. In this way, when the second oil circuit supplies oil to the rodless chamber of the injection cylinder 1, the first oil circuit can also replenish oil to a certain extent to the rodless chamber of the injection cylinder 1, thereby increasing the oil pressure on one side of the rodless chamber of the injection cylinder 1, and further increasing the oil pressure difference on both sides of the injection cylinder 1, so as to achieve the effect of multi-stage adjustable piston rod speed in the acceleration phase. Since valve A1 does not need to control its valve core stroke and the valve core displacement does not need to be adjusted, valve A1 can achieve a shorter full stroke opening time than the first servo valve in combination with a high-frequency response pilot switch valve, and thus the acceleration will be higher for inlet and outlet control.

[0043] Rapid phase, such as Figure 7As shown, after the acceleration stage, valve A2 and valve A3 are in a completely closed state, the oil in the accumulator 3 enters the rodless chamber of the injection cylinder 1 through the second oil circuit, and the oil in the rod chamber of the injection cylinder 1 flows back to the oil tank through the ninth oil circuit. By adjusting the opening 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 in the acceleration stage.

[0044] Braking phase, such as Figure 8 As shown, it is controlled by the third oil circuit, the second oil circuit and the ninth oil circuit. At the end of the rapid stage, the opening of the second servo valve (valve A8) is reduced to the boost pre-pressure position, so that the oil pressure on the rod chamber side of the injection cylinder 1 increases and approaches the oil pressure on the rod chamber side of the injection cylinder 1, and the piston rod in the injection cylinder 1 is decelerated and braked; valve A1 is directly closed after receiving the closing signal, and valve A4 is opened to prepare for the subsequent boost stage.

[0045] The boost phase, such as Fig. 9 As 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, thereby forming a boost A-bridge control. When boost is required, the pressure in the rod chamber of the boost cylinder 2 and the rod chamber of the injection cylinder 1 can be controlled by adjusting the opening ratio of the first servo valve and the second servo valve, thereby controlling the boost injection force. Specifically, the oil in the accumulator 3 enters the rodless chamber of the booster cylinder 2 through valve A4 (third oil circuit), increasing the oil pressure in the rodless chamber of the booster cylinder 2, and then balances the pressure difference on both sides of the piston rod of the booster cylinder 2 and the pressure difference on both sides of the piston rod of the injection cylinder 1 through the fourth oil circuit and the fifth oil circuit. Specifically, after the oil in the accumulator 3 passes through the first servo valve, a part of the oil directly enters the rod chamber of the booster cylinder 2. At this time, the oil pressure in the rodless chamber of the booster cylinder 2 is relatively balanced with the oil pressure in the rod chamber of the booster cylinder 2. Another part of the oil passes through valve A9 and enters the rod chamber of the injection cylinder 1 to balance the oil pressure on both sides of the piston rod of the injection cylinder 1. The excess oil pressure flows back to the oil tank through the second servo valve (valve A8). Among them, by increasing the opening of the first servo valve and reducing the opening of the second servo valve, the oil pressure on the entire cylinder assembly can be increased to achieve a boosting effect. It should be noted that in the oil circuit, only valve A1 and valve A3 are subjected to high pressure, and neither the first servo valve nor the second servo valve is subjected to high pressure. While reducing the risk of damage to the servo valve, a larger boost ratio can be designed to increase the rodless chamber pressure, thereby increasing the boost injection force.

[0046] Pressure relief stage, such as Fig.10As shown, it is controlled by the second oil circuit and the eleventh oil circuit. During this process, the oil pump supplies oil, and after the aforementioned many working processes, the oil pressure in the accumulator 3 decreases. At this time, valve A1 is opened, and the oil pump pumps the oil through valve A10 and 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 rodless chamber of the injection cylinder 1. The piston rod of the injection cylinder 1 begins to retract, and the oil in the rodless chamber of the injection cylinder 1 is replenished into the accumulator 3 to perform a pressure relief operation, and the oil that flows 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 loss of control during the tracking stage and avoid damaging the mold or product. When valve A1 is opened, the oil pressure in the rodless chamber of the injection cylinder 1 can quickly flow back to the accumulator 3.

[0047] Tracking phase, such as Fig.11 As shown, the control in the tracking stage is the same as that in the slow injection stage. Controlled by the differential circuit and the first oil circuit, since hydraulic energy has been stored in the accumulator 3 during the pressure relief stage, the accumulator 3 can still provide power during the tracking stage; at this time, at the inlet end of the cylinder assembly, valves A1, A4 and A5 are in a closed state, and the oil in the accumulator 3 can only enter the rodless 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 a closed state, and 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 rodless chamber side of the injection cylinder 1 to form a differential circuit.

[0048] It can be understood that, on both sides of the piston rod in the injection cylinder 1, the oil action area in the rod chamber is smaller than the oil action area in the rodless chamber. Therefore, in the tracking stage, the oil pressure in the rodless chamber of the injection cylinder 1 is greater than the oil pressure in the rodless chamber of the injection cylinder 1, and the piston rod of the injection cylinder 1 extends. In addition, the first servo valve (valve A2) is a small-diameter port. By adjusting the opening of the first servo valve, the oil pressure difference between the rodless chamber of the injection cylinder 1 and the rod chamber of the injection cylinder 1 can be controlled to decrease, thereby realizing the slow extension of the piston rod of the injection cylinder 1. In this way, the piston rod of the die-casting machine moves more smoothly during the tracking process, which can effectively protect the mold and the product.

Claims

1. A die-casting machine injection system, comprising a cylinder assembly formed by a series-connected injection cylinder and a booster cylinder; characterized in that: It also includes an accumulator, a first servo valve is provided between the accumulator and the inlet of the cylinder assembly, and a second servo valve is provided at the outlet of the cylinder assembly; During rapid control, the oil in the rod chamber of the injection cylinder flows back to the oil tank through the adjustment of the opening of the second servo valve; During boost control, the oil in the accumulator enters the rod chambers of the injection cylinder and the boost cylinder respectively through the first servo valve, and is discharged through the second servo valve. The boost injection force is adjusted by the opening ratio of the first servo valve and the second servo valve.

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

3. A die-casting machine injection system according to claim 2, characterized in that: It also includes a valve module, which includes a valve A3 and a valve A6. The valve A6 and the valve A3 are located on the differential circuit. The valve A6 is connected to the rod chamber of the injection cylinder, and the valve A3 is connected to the rodless chamber of the injection cylinder. The accumulator is connected in series with the first servo valve and the valve A3 in sequence to form a first oil circuit with the rodless chamber of the injection cylinder.

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

5. A die-casting machine injection system according to claim 3 or 4, characterized in that: The valve module further includes a valve A4, and the accumulator is connected to the valve A4 and forms a third oil circuit with the rodless chamber of the boosting cylinder.

6. A die-casting machine injection system according to claim 5, characterized in that: The valve module also includes a valve A9, the accumulator is connected to the first servo valve and forms a fourth oil circuit with the rod chamber of the booster cylinder, and the accumulator is connected in series with the first servo valve and valve A9 in sequence and forms a fifth oil circuit with the rod chamber of the injection cylinder.

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

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

9. A die-casting machine injection system according to claim 7, characterized in that: The valve module further comprises a valve A11 , and the output end of the oil pump is connected in series with the valve A11 and the valve A3 in sequence and forms a sixth oil circuit with the rodless chamber of the injection cylinder.

10. A die-casting machine injection system according to claim 8, characterized in that: The valve module also includes valve A5 and valve A7. The rodless chamber of the injection cylinder is connected to valve A3 and valve A5 in sequence and forms a seventh oil circuit with the oil tank. The rodless chamber of the booster cylinder is connected to valve A7 and forms an eighth circuit with the oil tank.

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