High-efficiency precision injection system

Abstract

The present invention relates to an efficient and precise injection system, which is characterized by adopting a specially designed double-set structure of a two-stage injection oil cylinder, which includes a displacement sensor, a two-stage injection oil cylinder, a first electric control valve, a second electric control valve, a third electric control valve, a fourth electric control valve and a servo valve; the two-stage injection oil cylinder is provided with a first piston, a first piston inner cavity, a second piston, a second piston inner cavity, a sealing plate, a first oil cavity, a second oil cavity, a third oil cavity, a connecting hole, a first oil cavity interface, a second oil cavity interface and a third oil cavity interface. The present invention can reasonably select the two-stage oil cylinder A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A110, A120, A130, A140, A150, A160, A170, A180, A190, A210, A220, A230, A240, A250, A260, A270, A280, A290, A310, A320, A330, A340, A350, A360, A370, A380, A390, A40, A50, A60, A70, A10 2、 The area of ​​A3 matches the requirements of each process for the injection force F, so the idle consumption of the injection cylinder of the present invention can be reduced to a minimum, thereby improving the system efficiency. In addition, since the injection system of the present invention can be fully closed-loop controlled in real time, the accuracy and stability of the injection process are guaranteed.

Description

Technical Field

[0001] The invention relates to a hydraulic system used on a metal die-casting machine or a metal extruder for extruding liquid metal into a mold to form a precise die-casting part, in particular to a high-efficiency precise injection system. Background Art

[0002] The traditional injection hydraulic system uses a conventional oil cylinder to inject liquid into the mold, and finally uses a booster piston to increase the pressure to obtain the die-cast parts. This type of system is inefficient, and the waste of the injection process often becomes the largest energy consumption link of the die-casting machine. Secondly, the control performance of the conventional injection process is poor, and the precision and quality of the die-cast parts are not ideal. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a high-efficiency and precise injection hydraulic system with low idle loss and high efficiency, and guaranteed accuracy and stability of the injection process.

[0004] According to the technical solution provided by the present invention, the high-efficiency precision injection system includes a displacement sensor, a two-stage injection cylinder, a first electric control valve, a second electric control valve, a third electric control valve, a fourth electric control valve and a servo valve;

[0005] The two-stage injection cylinder is provided with a first piston, a first piston inner cavity, a second piston, a second piston inner cavity, a sealing plate, a first oil cavity, a second oil cavity, a third oil cavity, a connecting hole, a first oil cavity interface, a second oil cavity interface and a third oil cavity interface;

[0006] The first piston in the two-stage injection oil cylinder divides the internal cavity of the injection oil cylinder into a first oil cavity and a second oil cavity. A displacement sensor is installed on the first piston rod of the first piston. A first piston inner cavity is opened inside the first piston. A second piston is slidably installed in the first piston inner cavity. A second piston rod is integrally fixed in the injection oil cylinder. The other end of the second piston rod is fixed to the second piston. A sealing plate is fixed on the first piston. The first piston inner cavity between the sealing plate and the second piston forms a third oil cavity. A second piston inner cavity is opened in the second piston rod. A connecting hole connecting the second piston inner cavity and the third oil cavity is opened on the second piston rod. A first oil cavity interface, a second oil cavity interface and a third oil cavity interface are opened on the injection oil cylinder. The first oil cavity interface is connected to the first oil cavity, the second oil cavity interface is connected to the second oil cavity, and the third oil cavity interface is connected to the second piston inner cavity. The effective areas of the first oil cavity are A1, the effective areas of the second oil cavity are A2, and the effective areas of the third oil cavity are A3.

[0007] The first pressure oil supply pipeline is connected to the oil inlet interface of the fourth electronically controlled valve, the oil outlet interface of the fourth electronically controlled valve is connected to the first interface of the first three-way valve, the second interface of the first three-way valve is connected to the oil inlet interface of the third electronically controlled valve, the oil outlet interface of the third electronically controlled valve is connected to the oil return pipeline, and the third interface of the first three-way valve is connected to the interface of the third oil chamber;

[0008] The second pressure oil supply pipeline is connected to the oil inlet interface of the servo valve, the oil outlet interface of the servo valve is connected to the first interface of the second tee, the second interface of the second tee is connected to the first oil chamber interface, the third interface of the second tee is connected to the oil inlet interface of the second electric control valve, the oil outlet interface of the second electric control valve is connected to the first interface of the third tee, the second interface of the third tee is connected to the second oil chamber interface, the third interface of the third tee is connected to the oil inlet interface of the first electric control valve, and the oil outlet interface of the first electric control valve is connected to the oil return pipeline.

[0009] It also includes an electronic amplifier, a signal input end of the electronic amplifier is connected to a signal output end of the displacement sensor, and a signal output end of the electronic amplifier is connected to a signal input end of the servo valve.

[0010] It also includes an oil pump, a safety valve, a non-return valve, an energy storage accumulator and a pressure sensor;

[0011] The inlet interface of the oil pump is connected to the oil tank, the oil outlet interface of the oil pump is connected to the first interface of the fourth three-way, the second interface of the fourth three-way is connected to the first interface of the fifth three-way, the second interface of the fifth three-way is connected to the first pressure oil supply pipeline, the third interface of the fifth three-way is connected to the oil inlet interface of the one-way valve, the oil outlet interface of the one-way valve is connected to the first interface of the first four-way, the second interface of the first four-way is connected to the second pressure oil supply pipeline, the third interface of the first four-way is connected to the pressure sensor, and the fourth interface of the first four-way is connected to the energy storage accumulator; the third interface of the fourth three-way is connected to the first interface of the sixth three-way, the second interface of the sixth three-way is connected to the oil inlet interface of the safety valve, the oil outlet interface of the safety valve is connected to the oil return pipeline, and the oil unloading port of the safety valve is connected to the third interface of the sixth three-way.

[0012] By means of different combinations of the first electrically controlled valve, the second electrically controlled valve, the third electrically controlled valve and the fourth electrically controlled valve, the first piston rod of the first piston can generate three different injection thrust outputs.

[0013] The real-time closed-loop control composed of the servo valve and the displacement sensor can accurately and reliably control the injection speed and injection thrust of the first piston rod of the first piston.

[0014] During the return stroke, the oil pump directly delivers the oil into the first piston inner cavity through the first oil cavity interface and the second piston inner cavity, and the high-pressure oil of the energy storage accumulator is not consumed during the return stroke.

[0015] Since the areas of A1, A2, and A3 can be reasonably selected in the present invention to match the requirements of each process for the injection force F, the idle consumption of the injection cylinder of the present invention can be reduced to a minimum, thereby improving the system efficiency. In addition, since the injection system of the present invention can be fully closed-loop controlled in real time, the accuracy and stability of the injection process are guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the present invention.

[0017] Figure 2 It is a specific implementation diagram of the present invention. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with specific embodiments.

[0019] The high-efficiency precision injection system of the present invention comprises a displacement sensor 6, an injection cylinder 7, a first electric control valve DF1, a second electric control valve DF2, a third electric control valve DF3, a fourth electric control valve DF4 and a servo valve SF;

[0020] The injection cylinder 7 is provided with a first piston 71, a first piston inner cavity 711, a second piston 72, a second piston inner cavity 721, a sealing plate 73, a first oil chamber S1, a second oil chamber S2, a third oil chamber S3, a connecting hole S4, a first oil chamber interface JK1, a second oil chamber interface JK2 and a third oil chamber interface JK3;

[0021] The first piston 71 in the injection cylinder 7 divides the internal cavity of the injection cylinder 7 into a first oil cavity S1 and a second oil cavity S2. A displacement sensor 6 is installed on the first piston rod of the first piston 71. A first piston inner cavity 711 is opened inside the first piston 71. A second piston 72 is slidably installed in the first piston inner cavity 711. A second piston rod is integrally fixed in the injection cylinder 7. The other end of the second piston rod is fixed to the second piston 72. A sealing plate 73 is fixed on the first piston 71. The sealing plate 73 and the second piston 72 are connected. The first piston inner cavity 711 between the two ends forms a third oil cavity S3, a second piston inner cavity 721 is provided in the second piston rod, a connecting hole S4 connecting the second piston inner cavity 721 and the third oil cavity S3 is provided on the second piston rod, a first oil cavity interface JK1, a second oil cavity interface JK2 and a third oil cavity interface JK3 are provided on the injection cylinder 7, the first oil cavity interface JK1 is connected to the first oil cavity S1, the second oil cavity interface JK2 is connected to the second oil cavity S2, and the third oil cavity interface JK3 is connected to the second piston inner cavity 721;

[0022] The first pressure oil supply pipeline is connected to the oil inlet interface of the fourth electronically controlled valve DF4, the oil outlet interface of the fourth electronically controlled valve DF4 is connected to the first interface of the first three-way valve, the second interface of the first three-way valve is connected to the oil inlet interface of the third electronically controlled valve DF3, the oil outlet interface of the third electronically controlled valve DF3 is connected to the oil return pipeline, and the third interface of the first three-way valve is connected to the third oil chamber interface JK3;

[0023] The second pressure oil supply pipeline is connected to the oil inlet interface of the servo valve SF, the oil outlet interface of the servo valve SF is connected to the first interface of the second tee, the second interface of the second tee is connected to the first oil chamber interface JK1, the third interface of the second tee is connected to the oil inlet interface of the second electric control valve DF2, the oil outlet interface of the second electric control valve DF2 is connected to the first interface of the third tee, the second interface of the third tee is connected to the second oil chamber interface JK2, the third interface of the third tee is connected to the oil inlet interface of the first electric control valve DF1, and the oil outlet interface of the first electric control valve DF1 is connected to the oil return pipeline.

[0024] The specific implementation also includes an electronic amplifier 9. The signal input end of the electronic amplifier 9 and the signal output end of the displacement sensor 6 form a position closed-loop control. The signal output end of the electronic amplifier 9 is connected to the signal input end of the servo valve SF. The displacement and speed curves required by the die-casting process are stored in the ROM register, and the electronic amplifier 9 is used to perform closed-loop control on the injection cylinder. The entire system can operate under the control of a PLC controller.

[0025] During the specific implementation, an external oil supply system is also required, such as an oil pump 1, a safety valve 2, a one-way valve 3, an energy storage accumulator 4 and a pressure sensor 5.

[0026] A double-stage injection cylinder 7 with a specially designed double-set structure is adopted to form three oil chambers, namely the first oil chamber S1, the second oil chamber S2 and the third oil chamber S3; the outside of the injection cylinder 7 is connected with four leak-free first electric-controlled valves DF1, the second electric-controlled valve DF2, the third electric-controlled valve DF3 and the fourth electric-controlled valve DF4. Under the control of PLC, four injection movements of different sizes and directions can be formed by relying on the different connections of the four electric-controlled valves to match the requirements of injection force and injection speed for different injection processes, so as to improve the energy efficiency of the liquid injection system and minimize the idle consumption.

[0027] In addition, a servo valve SF is connected to the main oil circuit, which allows closed-loop precision control of the speed of the injection cylinder, ensuring the accuracy and stability of the injection process.

[0028] The system principle of the present invention is shown in Figure 1The injection oil cylinder 7 adopts a double-set structure, thereby forming a first oil chamber S1, a second oil chamber S2 and a third oil chamber S3; their effective areas are A1, A2 and A3 respectively. The first electric control valve DF1, the second electric control valve DF2, the third electric control valve DF3 and the fourth electric control valve DF4 control the communication between the first oil chamber S1, the second oil chamber S2 and the third oil chamber S3, as well as the communication between the three oil chambers and the oil source P0 or the oil tank T. The first oil chamber S1 is connected to a high-speed proportional servo valve SF, which controls the oil pressure P1 in the first oil chamber S1, and together with the displacement sensor 6 installed on the piston rod of the first piston 71, can form a position closed-loop control system, so as to smoothly control the injection speed V or extrusion force F of the injection oil cylinder 7 throughout the entire process according to the control instructions.

[0029] The first piston 71 in the injection cylinder 7 divides the internal cavity of the injection cylinder into a first oil chamber S1 and a second oil chamber S2. A second piston 72 is installed inside the first piston 71. One end of the second piston rod is fixed to the cylinder body, and the other end of the second piston rod is fixed to the second piston. A sealing plate 73 is fixed to the first piston. A third oil chamber S3 is formed between the sealing plate 73 and the second piston. An oil through hole is opened in the second piston rod.

[0030] The pressure oil P0 is connected to the first three-way valve through the inlet, the first outlet end of the first three-way valve is connected to the inlet end of the fourth solenoid valve DF4, and the second outlet end of the first three-way valve is connected to the inlet end of the servo valve SF;

[0031] The outlet end of the servo valve SF is connected to the inlet end of the second tee, the first outlet end of the second tee is connected to the first oil chamber S1, the second outlet end of the second tee is connected to the inlet end of the second solenoid valve DF2, the outlet end of the second solenoid valve DF2 is connected to the first inlet end of the third tee, the second oil chamber S2 is connected to the second inlet end of the third tee, the outlet end of the third tee is connected to the inlet end of the first solenoid valve DF1, and the outlet end of the first solenoid valve DF1 is connected to the oil return pipe of the oil tank through the fourth tee.

[0032] When the second solenoid valve DF2 and the fourth solenoid valve DF4 are turned on, the injection force F is the minimum at this time, F=(A1-A2)×P1-A3×P0, which can be used to inject molten metal into the mold.

[0033] When the second solenoid valve DF2 and the third solenoid valve DF3 are turned on, the injection force F is slightly larger at this time, F=(A1-A2)×P1, so that the molten metal fills the mold.

[0034] When the first solenoid valve DF1 and the third solenoid valve DF3 are turned on, the injection force F is at its maximum F=A1×P1, which can fully compact the casting.

[0035] When the first electromagnetic valve DF1, the second electromagnetic valve DF2, and the fourth electromagnetic valve DF4 are turned on, the injection force F is reversed to empty the barrel and prepare for re-addition.

[0036] When working, the motor-driven oil pump 1 draws oil from the oil tank and presses it into the accumulator 4 through the one-way valve 3. The pressure sensor 5 detects the oil pressure of the accumulator 4. When the oil pressure reaches the upper limit P max When the oil pressure drops below the lower limit P, the motor stops. min When the motor is restarted, the oil is replenished into the accumulator 4, so that the inlet of the servo valve SF always has sufficient pressure oil, ensuring that the servo valve SF can stably control the injection speed or extrusion pressure of the injection cylinder. At the outlet of the oil pump 1, there is another safety valve 2, which can protect the oil pump 1 from overpressure and damage when the pressure replenishment system fails.

[0037] Metal injection can be roughly divided into four steps;

[0038] 1. Liquid injection process: Liquid metal is injected into the mold cavity. At this time, due to the good fluidity of liquid metal, only a small thrust is required to inject the metal into the mold cavity.

[0039] 2. Mold filling process: As the metal in the mold cavity is gradually filled, the resistance of the injection flow channel increases, and higher pressure is required to completely fill the mold.

[0040] 3. Extrusion process: The mold cavity is completely filled with metal, and the surface of the casting has partially solidified. In order to make the casting fit the mold cavity precisely and compensate for the shrinkage and looseness during solidification, the injection system needs to increase a large injection force, such as reaching more than 80Mpa, and maintain it for several seconds.

[0041] 4. Return process: The injection cylinder returns to the starting position to remove the parts, empty the barrel, and prepare for the next die casting. At this time, the cylinder returns in an empty state.

[0042] During the injection process: the first and third electrically controlled valves DF1 and DF3 are closed, and the second and fourth electrically controlled valves DF2 and DF4 are opened.

[0043] Therefore, the injection force F = (A1-A2)P1-A1P0; if the injection process stroke is L1, the required oil volume is Q1 = L1×(A1-A2-A3).

[0044] During the mold filling process: the first electric control valve DF1 and the fourth electric control valve DF4 are closed, and the second electric control valve DF2 and the fourth electric control valve DF4 are opened.

[0045] Injection force F = (A1-A2) × P1, the filling process stroke is L2,

[0046] The amount of oil required for filling the mold is Q2 = L2 × (A1-A2).

[0047] During the extrusion process: the first and third electrically controlled valves DF1 and DF3 are open, and the second and fourth electrically controlled valves DF2 and DF4 are closed.

[0048] The injection force F = A1 × P1, the extrusion process stroke is L3,

[0049] The amount of oil required for extrusion is Q3=L3×A1.

[0050] During the return trip, the first electrically controlled valve DF1, the second electrically controlled valve DF2, and the fourth electrically controlled valve DF4 are opened, and the third electrically controlled valve DF3 is closed.

[0051] During the return stroke, the oil pump directly delivers the oil into the third oil chamber S3. The high-pressure oil of the accumulator is not consumed during the return stroke. Since the return resistance is very small, the return pressure P R It is also very small, and the motor power consumption is very low at this time.

[0052] Table 1 lists the thrust and oil volume of each process cylinder.

[0053] Table 1

[0054]

[0055] From the above analysis, it can be seen that as long as the area ratio A1:A2:A3 of the two-stage cylinder is reasonably selected, the injection force and injection resistance can be well matched, the hydraulic energy of the oil source can be fully utilized, and the injection efficiency can be greatly improved.

[0056] In the circuit of the present invention, the displacement sensor 6, the electronic amplifier 9 and the high-speed proportional servo valve SF constitute a closed-loop control system, and the speed and pressure of each section of the injection process can be controlled by the high-speed proportional servo valve SF. Therefore, the accuracy and stability of the injection process are reliably guaranteed.

[0057] Depending on different combinations of the first electrically controlled valve DF1 , the second electrically controlled valve DF2 , the third electrically controlled valve DF3 and the fourth electrically controlled valve DF4 , the first piston rod of the first piston 71 can generate three different injection thrust outputs.

[0058] The servo valve SF and the displacement sensor 6 form a real-time closed-loop control, which can accurately and reliably control the injection speed and injection thrust of the first piston rod of the first piston 71.

[0059] During the return stroke, the oil pump 1 directly delivers the oil into the first piston inner cavity 711 through the first oil chamber interface JK1 and the second piston inner cavity 721. The high-pressure oil of the energy storage accumulator 4 is not consumed during the return stroke. Since the return resistance is very small, the return pressure is very small. At this time, the motor power consumption of the oil pump 1 is very low.

Claims

1. A high-efficiency precision injection system, characterized by: It comprises a displacement sensor (6), a two-stage injection oil cylinder (7), a first electrically controlled valve (DF1), a second electrically controlled valve (DF2), a third electrically controlled valve (DF3), a fourth electrically controlled valve (DF4) and a servo valve (SF); The two-stage injection cylinder (7) is provided with a first piston (71), a first piston inner cavity (711), a second piston (72), a second piston inner cavity (721), a sealing plate (73), a first oil cavity (S1), a second oil cavity (S2), a third oil cavity (S3), a connecting hole (S4), a first oil cavity interface (JK1), a second oil cavity interface (JK2) and a third oil cavity interface (JK3); The first piston (71) in the two-stage injection oil cylinder (7) divides the internal cavity of the injection oil cylinder (7) into a first oil cavity (S1) and a second oil cavity (S2). A displacement sensor (6) is installed on the first piston rod of the first piston (71). A first piston inner cavity (711) is provided inside the first piston (71). A second piston (72) is slidably installed in the first piston inner cavity (711). A second piston rod is integrally fixed in the two-stage injection oil cylinder (7). The other end of the second piston rod is fixed to the second piston (72). A sealing plate (73) is fixed to the first piston (71). The sealing plate (73) and the second piston (72) are connected to each other. 72) forms a third oil chamber (S3), a second piston inner chamber (711) is provided in the second piston rod, a connecting hole (S4) connecting the second piston inner chamber (721) and the third oil chamber (S3) is provided on the second piston rod, a first oil chamber interface (JK1), a second oil chamber interface (JK2) and a third oil chamber interface (JK3) are provided on the two-stage injection cylinder (7), the first oil chamber interface (JK1) is connected to the first oil chamber (S1), the second oil chamber interface (JK2) is connected to the second oil chamber (S2), and the third oil chamber interface (JK3) is connected to the second piston inner chamber (721); The first pressure oil supply pipeline is connected to the oil inlet interface of the fourth electric control valve (DF4), the oil outlet interface of the fourth electric control valve (DF4) is connected to the first interface of the first three-way connection, the second interface of the first three-way connection is connected to the oil inlet interface of the third electric control valve (DF3), the oil outlet interface of the third electric control valve (DF3) is connected to the oil return pipeline, and the third interface of the first three-way connection is connected to the third oil chamber interface (JK3); The second pressure oil supply pipeline is connected to the oil inlet interface of the servo valve (SF), the oil outlet interface of the servo valve (SF) is connected to the first interface of the second tee, the second interface of the second tee is connected to the first oil chamber interface (JK1), the third interface of the second tee is connected to the oil inlet interface of the second electric control valve (DF2), the oil outlet interface of the second electric control valve (DF2) is connected to the first interface of the third tee, the second interface of the third tee is connected to the second oil chamber interface (JK2), the third interface of the third tee is connected to the oil inlet interface of the first electric control valve (DF1), and the oil outlet interface of the first electric control valve (DF1) is connected to the oil return pipeline; It also includes an oil pump (1), a safety valve (2), a one-way valve (3), an energy storage accumulator (4) and a pressure sensor (5); The oil inlet interface of the oil pump (1) is connected to the oil tank, the oil outlet interface of the oil pump (1) is connected to the first interface of the fourth three-way, the second interface of the fourth three-way is connected to the first interface of the fifth three-way, the second interface of the fifth three-way is connected to the first pressure oil supply pipeline, the third interface of the fifth three-way is connected to the oil inlet interface of the one-way valve (3), the oil outlet interface of the one-way valve (3) is connected to the first interface of the first four-way, the second interface of the first four-way is connected to the second pressure oil supply pipeline, the third interface of the first four-way is connected to the pressure sensor (5), and the fourth interface of the first four-way is connected to the energy storage accumulator (4); the third interface of the fourth three-way is connected to the first interface of the sixth three-way, the second interface of the sixth three-way is connected to the oil inlet interface of the safety valve (2), the oil outlet interface of the safety valve (2) is connected to the oil return pipeline, and the oil discharge port of the safety valve (2) is connected to the third interface of the sixth three-way; By means of different combinations of the first electrically controlled valve (DF1), the second electrically controlled valve (DF2), the third electrically controlled valve (DF3) and the fourth electrically controlled valve (DF4), the first piston rod of the first piston (71) can generate three different injection thrust outputs; During the return stroke, the oil pump (1) directly delivers oil into the first piston inner cavity (711) through the first oil cavity interface (JK1) and the second piston inner cavity (721), and the high-pressure oil of the energy storage accumulator (4) is not consumed during the return stroke.

2. The high-efficiency precision injection system according to claim 1, characterized in that: It also includes an electronic amplifier (9), wherein a signal input end of the electronic amplifier (9) is connected to a signal output end of the displacement sensor (6), and a signal output end of the electronic amplifier (9) is connected to a signal input end of a servo valve (SF).

3. The high-efficiency precision injection system according to claim 1, characterized in that: A real-time closed-loop control system consisting of a servo valve (SF) and a displacement sensor (6) can accurately and reliably control the injection speed and injection thrust of the first piston rod of the first piston (71).

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