A closed-loop control oil circuit system for oil cylinder speed and pressure

Abstract

The present invention relates to the technical field of closed-loop oil circuits for controlling cylinder speed and pressure. The present invention provides an oil circuit system for closed-loop oil circuits for controlling cylinder speed and pressure, comprising: a primary oil cylinder, a secondary oil cylinder, an accumulator, a pressure source, and an oil tank; the primary oil cylinder is provided with a rod chamber and a rodless chamber, the first end of the rodless chamber being connected to the oil tank via a first valve; a charging valve is provided between the rodless chamber of the primary oil cylinder and the accumulator, one end of the charging valve being connected to the first end of the rod chamber of the secondary oil cylinder; the rodless chamber of the secondary oil cylinder is connected to multiple valves, each of which is connected to a pressure source and an oil tank; the second end of the rod chamber of the primary oil cylinder is connected to a second valve, the second valve being connected to the pressure source via a first one-way valve; a safety valve is connected to the first valve, the rod chamber of the primary oil cylinder is connected to the safety valve, and one end of the safety valve is connected to the oil tank. The present invention can achieve good oil circuit control effects, low cost, energy saving, and a wide range of applications.

Description

Technical Field

[0001] The present invention relates to the technical field of oil circuits for closed-loop control of oil cylinder speed and pressure, and in particular to an oil circuit system for closed-loop control of oil cylinder speed and pressure. Background Art

[0002] A die-casting machine is a machine used for pressure casting. Under pressure, the machine hydraulically injects molten metal into a mold, where it cools and forms the part. After the mold is opened, a solid metal casting is obtained. Shot control in a die-casting machine is divided into three stages: slow, fast, and boost. Slow and fast control the speed of the injection cylinder according to process requirements, while boost controls the injection force according to process requirements.

[0003] At present, most die-casting machines at home and abroad use two sets of accumulators to control the speed and pressure of injection separately. This is not only costly, but also has a narrow pressure control range and a small scope of application. Summary of the Invention

[0004] In view of the deficiencies of the above related technologies, the present invention proposes an oil circuit system for closed-loop control of oil cylinder speed and pressure, which has low cost, good pressure control effect and wide adaptability.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a closed-loop control oil circuit system for oil cylinder speed and pressure, comprising: a primary oil cylinder, a secondary oil cylinder, an accumulator, a pressure source, and an oil tank;

[0006] The first-stage oil cylinder is provided with a rod chamber and a rodless chamber, the first end of the rod chamber is connected to the oil tank through a first valve, a charging valve is provided between the rodless chamber of the first-stage oil cylinder and the accumulator, one end of the charging valve is connected to the first end of the rod chamber of the second-stage oil cylinder, the rodless chamber of the second-stage oil cylinder is connected to a plurality of valves, and the plurality of valves are respectively connected to the pressure source and the oil tank;

[0007] The second end of the rod chamber of the first-level oil cylinder is connected to the second valve, the second valve is connected to the pressure source through a first one-way valve, the first valve is connected to a safety valve, the rod chamber of the first-level oil cylinder is connected to the safety valve, and one end of the safety valve is connected to the oil tank.

[0008] Preferably, the accumulator is further provided with a piston position detection device and a first pressure sensor.

[0009] Preferably, the secondary oil cylinder is provided with a piston rod cavity, and the rodless cavity of the primary oil cylinder is connected to the piston rod cavity.

[0010] Preferably, a second pressure sensor is provided on the rod chamber of the first-stage oil cylinder, and a third pressure sensor is provided on the rodless chamber of the first-stage oil cylinder.

[0011] Preferably, the first-stage oil cylinder is further provided with a piston rod, and a position sensor is mounted on the piston rod.

[0012] Preferably, the cylinder speed and pressure closed-loop control oil circuit system also includes a third valve, the first end of the third valve is connected to the rod chamber of the secondary cylinder, and the second end of the third valve is connected to the first valve and the second valve respectively.

[0013] Preferably, the multiple valves include a fourth valve, a fifth valve, a sixth valve and a seventh valve. The rodless chamber of the secondary cylinder is connected to the accumulator and the fourth valve through the seventh valve. The accumulator is also connected to the fifth valve and the sixth valve. The fifth valve is connected to the pressure source through the first one-way valve, and the sixth valve is connected to the oil tank.

[0014] Preferably, the rodless chamber of the secondary oil cylinder and the sixth valve are connected via a second one-way valve.

[0015] Preferably, an eighth valve is connected below the filling valve, and one end of the eighth valve is connected to the first valve.

[0016] Preferably, the oil circuit system for closed-loop control of cylinder speed and pressure further includes a third one-way valve and a fourth one-way valve, wherein the third one-way valve is connected to the second valve, and the fourth one-way valve is connected to the accumulator.

[0017] Compared with the related art, the present invention provides a rod chamber and a rodless chamber on the first-stage oil cylinder, the first end of the rod chamber is connected to the oil tank through the first valve, and there is a filling valve between the rodless chamber of the first-stage oil cylinder and the accumulator, one end of the filling valve is connected to the first end of the rod chamber of the second-stage oil cylinder, the rodless chamber of the second-stage oil cylinder is connected to multiple valves, and the multiple valves are respectively connected to the pressure source and the oil tank; the second end of the rod chamber of the first-stage oil cylinder is connected to the second valve, the second valve is connected to the pressure source through the first one-way valve, a safety valve is connected to the first valve, the rod chamber of the first-stage oil cylinder is connected to the safety valve, and one end of the safety valve is connected to the oil tank; by controlling the first valve and the second valve, differential can be achieved in the slow stage to save energy, and in the boost stage, the pressure output of the first-stage oil cylinder can be adjusted by controlling the pressure of the rod chambers of the first-stage oil cylinder and the second-stage oil cylinder. By adjusting the pressure output of the first-stage oil cylinder in this way, the injection force adjustment range is wide, the cost is low, energy saving is achieved, and it is widely adaptable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be described in detail below with reference to the accompanying drawings. The above and other aspects of the present invention will become clearer and easier to understand through the detailed description made with reference to the following drawings. In the accompanying drawings:

[0019] Figure 1 Schematic diagram of the structure of the oil circuit system for closed-loop control of oil cylinder speed and pressure of the present invention;

[0020] Figure 2 It is a structural schematic diagram of the first-stage oil cylinder and the second-stage oil cylinder of the present invention;

[0021] Figure 3 Schematic diagram of the oil flow direction in the slow phase of the oil circuit system for closed-loop control of oil cylinder speed and pressure of the present invention;

[0022] Figure 4 Schematic diagram of the oil flow direction in the fast injection phase of the oil circuit system for closed-loop control of oil cylinder speed and pressure according to the present invention;

[0023] Figure 5 Schematic diagram of the oil flow direction in the pressurization stage of the oil circuit system for closed-loop control of oil cylinder speed and pressure of the present invention;

[0024] Figure 6 Schematic diagram of the oil flow direction during the hammering phase of the oil circuit system for closed-loop control of oil cylinder speed and pressure according to the present invention;

[0025] Figure 7 Schematic diagram of the oil flow direction during the energy storage phase of the oil circuit system for closed-loop control of cylinder speed and pressure of the present invention. DETAILED DESCRIPTION

[0026] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] The specific embodiments / examples described herein are specific embodiments of the present invention and are used to illustrate the concept of the present invention. They are illustrative and exemplary and should not be construed as limiting the embodiments of the present invention or the scope of the present invention. In addition to the examples described herein, those skilled in the art can also adopt other obvious technical solutions based on the claims and the disclosure of the specification. These technical solutions, including any obvious replacements and modifications of the embodiments described herein, are all within the scope of protection of the present invention.

[0028] Please refer to Figure 1-7As shown, the present invention provides a cylinder speed and pressure closed-loop control oil circuit system 100, including: a primary cylinder 18, a secondary cylinder 15, an accumulator 20, a pressure source 24 and an oil tank 23. The first-level oil cylinder 18 is provided with a rod chamber 27 and a rodless chamber 28. The first end of the rod chamber 27 is connected to the oil tank 23 through a first valve 3. There is a filling valve 16 between the rodless chamber 28 of the first-level oil cylinder 18 and the accumulator 20. One end of the filling valve 16 is connected to the first end of the rod chamber 30 of the second-level oil cylinder 15. The rodless chamber 31 of the second-level oil cylinder 15 is connected to multiple valves, and the multiple valves are respectively connected to the pressure source 24 and the oil tank 23; the second end of the rod chamber 27 of the first-level oil cylinder 18 is connected to the second valve 2, and the second valve 2 is connected to the pressure source 24 through a first one-way valve 1. The first valve 3 is connected to a safety valve 4. The rod chamber 27 of the first-level oil cylinder 18 is connected to the safety valve 4, and one end of the safety valve 4 is connected to the oil tank 23. By controlling the first valve 3 and the second valve 2 in the slow stage, differential operation can be achieved to save energy. In the boost stage, the pressure output by the first-stage oil cylinder 18 and the second-stage oil cylinder 15 can be controlled by controlling the pressure in the rod chamber 30 to adjust the pressure output by the first-stage oil cylinder 18. By adjusting the pressure output by the first-stage oil cylinder 18 in this way, the injection force adjustment range is wide, the cost is low, energy saving is achieved, and it is widely adaptable.

[0029] A fourth pressure sensor 5 is further provided between the first-stage oil cylinder 18 and the first valve 3 . The fourth pressure sensor 5 is used to detect the oil pressure passing between the first-stage oil cylinder 18 and the first valve 3 .

[0030] Specifically, by opening the charging valve 16, hydraulic oil flows from the accumulator 20 into the primary cylinder 18. The primary cylinder 18 controls the closing of the first valve 3 and the opening of the second valve 2. The second valve 2 is opened to a predetermined opening according to a preset set speed. With multiple valves open, hydraulic oil flows from the rod chamber 27 of the primary cylinder 18 back to the rodless chamber 28 of the primary cylinder 18, achieving slow-speed operation. The rod chamber 27 of the primary cylinder 18 is used to control the cylinder back pressure, thereby controlling the injection speed and boost pressure.

[0031] Specifically, by connecting the rod chamber 27 of the first-stage oil cylinder 18 to the safety valve 4 at the same time, and the safety valve 4 to the oil tank 23, the front chamber pressure can be effectively limited to prevent malfunction of the injection, which makes the front chamber pressure very high and causes the front cover screws of the oil cylinder to break.

[0032] Specifically, by opening the charging valve 16, hydraulic oil flows from the accumulator 20 into the primary cylinder 18. The primary cylinder 18 controls the closing of the second valve 2. The first valve 3 and multiple valves can be opened to a predetermined degree based on a set speed, thereby achieving the fast injection stage. Optionally, the set speed can be 1 L / min, 5 L / min, 10 L / min, etc., depending on the actual size of the equipment, and will not be described here.

[0033] Specifically, by closing the filling valve 16 and opening multiple valves, the piston of the secondary cylinder 15 moves forward, and the first valve 3 and the second valve 2 work simultaneously to control the output injection force of the piston rod 29 of the primary cylinder 18 to achieve the boosting stage.

[0034] Specifically, by closing the first valve 3 and opening multiple valves, the oil in the accumulator 20 enters the rod chamber 30 of the first-level cylinder 18 and the second-level cylinder 15, and the oil in the rodless chamber 31 of the first-level cylinder 18 and the second-level cylinder 15 returns to the oil tank 23 through the valve to realize the back hammer stage.

[0035] Specifically, hydraulic oil is provided by the pressure source 24, passes through the first one-way valve 1, and multiple valves are opened to enter the accumulator 20 for energy storage. When the hydraulic oil in the accumulator 20 is full, the piston of the accumulator 20 hits the piston position detection device 22 to stop storing energy and realize the energy storage stage.

[0036] In this embodiment, the accumulator 20 is further equipped with a piston position detection device 22 and a first pressure sensor 21. The piston position detection device 22 is used to detect whether the oil in the accumulator 20 is fully charged. If the oil is fully charged, the piston in the accumulator 20 will rise and hit the position detection device. The first pressure sensor 21 is used to detect whether the pressure in the accumulator 20 has reached the set value to ensure that the pressure is correct.

[0037] In this embodiment, the secondary cylinder 15 is provided with a piston rod chamber 32, to which the rodless chamber 28 of the primary cylinder 18 is connected. The piston rod chamber 32 is used for boosting pressure. The boosting cylinder is divided into a rodless chamber, a rod chamber, and a piston rod chamber. A servo valve is connected through the rod chamber 30, which controls the pressure in the rod chamber and, therefore, the piston rod chamber 32.

[0038] In this embodiment, a second pressure sensor 17 is provided on the rod chamber 27 of the first-stage oil cylinder 18, and a third pressure sensor 25 is provided on the rodless chamber 28 of the first-stage oil cylinder 18. The second pressure sensor 17 is used to detect the oil pressure in the rod chamber 27 of the first-stage oil cylinder 18, and controls the back pressure of the first-stage oil cylinder 18 through the rod chamber 27, thereby controlling the injection speed and boost pressure. The third pressure sensor 25 is used to detect the oil pressure in the rodless chamber 28 of the first-stage oil cylinder 18, and controls the back pressure of the first-stage oil cylinder 18 through the rodless chamber 28, thereby controlling the injection speed and boost pressure.

[0039] In this embodiment, the primary oil cylinder 18 is further provided with a piston rod 29, on which a position sensor 19 is mounted. The position sensor 19 can detect the moving position of the piston rod 29 in real time, with good detection effect.

[0040] In this embodiment, the cylinder speed and pressure closed-loop control oil circuit system 100 further includes a third valve 7 . The first end of the third valve 7 is connected to the rod chamber 30 of the secondary cylinder 15 , and the second end of the third valve 7 is connected to the first valve 3 and the second valve 2 , respectively. This facilitates the flow of oil pressure from the secondary cylinder 15 from the third valve 7 to the first valve 3 and the second valve 2 , and then through the second valve 2 from the first check valve 1 to the pressure source 24 .

[0041] In this embodiment, the multiple valves include a fourth valve 10, a fifth valve 11, a sixth valve 12 and a seventh valve 13. The rodless chamber 31 of the secondary cylinder 15 is connected to the accumulator 20 and the fourth valve 10 through the seventh valve 13. The accumulator 20 is also connected to the fifth valve 11 and the sixth valve 12. The fifth valve 11 is connected to the pressure source 24 through the first one-way valve 1, and the sixth valve 12 is connected to the oil tank 23.

[0042] In this embodiment, the rodless chamber 31 of the secondary oil cylinder 15 and the sixth valve 12 are connected via a second one-way valve 14 .

[0043] In this embodiment, an eighth valve 6 is further connected below the filling valve 16 , and one end of the eighth valve 6 is connected to the first valve 3 .

[0044] In this embodiment, the cylinder speed and pressure closed-loop control oil system 100 further includes a third one-way valve 8 and a fourth one-way valve 9. The third one-way valve is connected to the second valve 2, and the fourth one-way valve 9 is connected to the accumulator 20. One end of each of the third and fourth one-way valves 8 and 9 is connected to a filter 26. One end of the filter 26 is connected to the first valve 3, which is in turn connected to the oil tank 23. This filter filters the oil in the oil tank 23, saving costs.

[0045] In this embodiment, the piston rod chamber 32 of the secondary oil cylinder 15 has an area of ​​A1 and a pressure of P1. The area of ​​the rod chamber 30 is A2 and the pressure is P2. The area of ​​the rodless chamber 31 is A and the pressure is P. Here, A1 × P1 + A2 × P2 = A × P, and P1 = (A × P - A2 × P2) / A1. Since A, P, and A2 are all constant values, controlling the pressure of P2 can control the pressure of P1, resulting in effective control and ease of use.

[0046] In this embodiment, please refer to Figure 3-7As shown, the working principle of the present invention is as follows:

[0047] In the slow speed stage, by opening the charging valve 16, the hydraulic oil enters the rodless chamber 28 of the first-stage cylinder 18 from the accumulator 20, the first valve 3 connected to the rod chamber 27 of the first-stage cylinder 18 is closed, the second valve 2 is given an opening according to the user-set speed, the fifth valve 11 is opened, and the hydraulic oil returns from the rod chamber 27 of the first-stage cylinder 18 to the rodless chamber 28 of the first-stage cylinder 18.

[0048] In the fast injection stage, by opening the charging valve 16, the hydraulic oil enters the rear chamber of the first-stage cylinder 18 from the accumulator 20, the second valve 2 connected to the first-stage cylinder 18 is closed, and the first valve 3 and the fifth valve 11 are given an opening according to the speed set by the user.

[0049] During the pressurization phase, the charging valve 16 is closed, the third valve 7, the fifth valve 11, and the seventh valve 13 are opened, the piston of the secondary oil cylinder 15 advances, and the first valve 3 and the second valve 2 operate simultaneously to control the output injection force of the piston rod of the primary oil cylinder 18. The injection force refers to the force (pressure x area of ​​the rodless chamber) in the rodless chamber 28 of the primary oil cylinder 18 and the force (pressure x area of ​​the rod chamber) in the rod chamber 27 of the primary oil cylinder 18. Pressure changes in the rod chamber 27 will cause pressure changes in the primary oil cylinder 18. The first valve 3 is responsible for releasing oil from the rod chamber 27 of the oil cylinder, and the second valve 2 is responsible for releasing oil into the rod chamber 27. When the oil release from the first valve 3 is greater than the oil inlet from the second valve 2, the pressure in the rod chamber 27 of the oil cylinder will decrease; when the oil release from the first valve 3 is less than the oil inlet from the second valve 2, the pressure in the rod chamber 27 of the primary oil cylinder 18 will increase.

[0050] During the back-hammering stage, the first valve 3 is closed, the sixth valve 12, the second valve 2, the fifth valve 11, and the sixth valve 12 are opened, the oil in the accumulator 20 enters the rod chamber 30 of the first-stage cylinder 18 and the second-stage cylinder 15, and the oil in the rodless chamber 31 of the first-stage cylinder 18 and the second-stage cylinder 15 returns to the oil tank 23 through the sixth valve 12.

[0051] During the energy storage phase, the pressure source 24 provides hydraulic oil, which passes through the one-way valve 1, the fifth valve 11 opens, and enters the accumulator 20 for energy storage. When the hydraulic oil in the accumulator 20 is full, the piston of the accumulator 20 hits the piston position detection device 22 and stops energy storage.

[0052] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be encompassed within the scope of the claims.

Claims

1. A closed-loop control oil circuit system for oil cylinder speed and pressure, characterized in that: include: Primary cylinder, secondary cylinder, accumulator, pressure source and oil tank; The first-stage oil cylinder is provided with a rod chamber and a rodless chamber, the first end of the rod chamber is connected to the oil tank through a first valve, a charging valve is provided between the rodless chamber of the first-stage oil cylinder and the accumulator, one end of the charging valve is connected to the first end of the rod chamber of the second-stage oil cylinder, the rodless chamber of the second-stage oil cylinder is connected to a plurality of valves, and the plurality of valves are respectively connected to the pressure source and the oil tank; The second end of the rod chamber of the first-stage oil cylinder is connected to a second valve, the second valve is connected to the pressure source via a first one-way valve, the first valve is connected to a safety valve, the rod chamber of the first-stage oil cylinder is connected to the safety valve, and one end of the safety valve is connected to the oil tank; The accumulator is also provided with a piston position detection device and a first pressure sensor; The oil circuit system for closed-loop control of oil cylinder speed and pressure further includes a third valve, a first end of the third valve being connected to the rod chamber of the secondary oil cylinder, and a second end of the third valve being connected to the first valve and the second valve respectively; The multiple valves include a fourth valve, a fifth valve, a sixth valve and a seventh valve. The rodless chamber of the secondary cylinder is connected to the accumulator and the fourth valve through the seventh valve. The accumulator is also connected to the fifth valve and the sixth valve. The fifth valve is connected to the pressure source through the first one-way valve, and the sixth valve is connected to the oil tank.

2. The oil cylinder speed and pressure closed-loop control oil circuit system according to claim 1, characterized in that: The secondary oil cylinder is provided with a piston rod cavity, and the rodless cavity of the primary oil cylinder is connected to the piston rod cavity.

3. The oil cylinder speed and pressure closed-loop control oil circuit system according to claim 1, characterized in that: A second pressure sensor is provided on the rod chamber of the first-stage oil cylinder, and a third pressure sensor is provided on the rodless chamber of the first-stage oil cylinder.

4. The oil cylinder speed and pressure closed-loop control oil circuit system according to claim 3, characterized in that: The first-stage oil cylinder is also provided with a piston rod, on which a position sensor is mounted.

5. The oil cylinder speed and pressure closed-loop control oil circuit system according to claim 1, characterized in that: The rodless chamber of the secondary oil cylinder is connected to the sixth valve via a second one-way valve.

6. The oil cylinder speed and pressure closed-loop control oil circuit system according to claim 1, characterized in that: An eighth valve is further connected under the liquid filling valve, and one end of the eighth valve is connected to the first valve.

7. The oil cylinder speed and pressure closed-loop control oil circuit system according to claim 1, characterized in that: The oil circuit system for closed-loop control of oil cylinder speed and pressure further includes a third one-way valve and a fourth one-way valve, wherein the third one-way valve is connected to the second valve, and the fourth one-way valve is connected to the accumulator.

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