Micro-foamed hydraulic control circuit

Abstract

This utility model relates to the field of micro-foaming hydraulic control circuit technology, and in particular to a micro-foaming hydraulic control circuit, including an oil tank, a delivery pump, an injection cylinder, and a first three-position four-way directional valve. The B port of the first three-position four-way directional valve is connected to the rod chamber of the injection cylinder, and the T port of the first three-position four-way directional valve is connected to the oil tank. It also includes a circuit switch control mechanism for controlling the nozzle switch. The circuit switch control mechanism includes a control cylinder, an accumulator, a first pressure reducing valve, a second three-position four-way directional valve, a second pressure reducing valve, and a two-position four-way directional valve. In use, by setting the circuit switch control mechanism for the nozzle switch, the delivery pump continuously provides the upper limit pressure to the injection cylinder through the circuit switch control mechanism. The first three-position four-way directional valve and the two-position four-way directional valve jointly perform back pressure control. The back pressure setting can be adjusted according to the material characteristics. The injection pressure is controllable, and there is no pressure holding process, realizing the physical foaming application of ordinary injection molding machines.

Description

Technical Field

[0001] This utility model relates to the field of micro-foamed hydraulic control circuit technology, and in particular to a micro-foamed hydraulic control circuit. Background Technology

[0002] Lightweight design is one of the future trends in plastics processing technology. Lightweighting of plastics not only helps save on raw material costs, but also means improved overall product performance and competitiveness for industries such as automotive and aerospace. Microcellular foam injection molding is a new technology developed in this context. Its biggest advantage lies in its ability to further unleash the potential for lightweighting plastics. At the same time, this technology can also reduce shrinkage marks, warpage, and internal stress areas, lower clamping forces and injection pressures, achieving energy conservation and environmental protection. Microcellular foaming can be further divided into physical foaming and chemical foaming in terms of technical implementation. Physical foaming, due to the purity of the materials used, has a finer cell structure and more stable performance, and is therefore widely used.

[0003] Physical foaming, also known as supercritical foaming, works by treating gases such as carbon dioxide and nitrogen under high temperature and pressure, then injecting them into the screw of an injection molding machine. Simultaneously, the gases pass through a plasticizing sol, causing the gas and plastic to form a supercritical fluid that is in a molten state, somewhere between a liquid and a gas.

[0004] Maintaining a supercritical fluid state is quite demanding, requiring injection molding machines to provide appropriate temperature and pressure control. For temperature control, ordinary injection molding machine barrels already contain heating coils; configuration simply depends on the specifications of the plasticizing screw. However, ordinary injection molding machines lack this pressure control function. Generally, after plasticizing, ordinary injection molding machines require releasing the back pressure of the injection cylinder to prevent molten plastic from flowing out of the nozzle. However, for injection molding machines used in physical foaming applications, the back pressure of the injection cylinder must be continuously maintained to prevent the supercritical state from being disrupted. Utility Model Content

[0005] The technical problem to be solved by this utility model is: in order to solve the problem that after plasticizing, ordinary injection molding machines require the back pressure of the injection cylinder to be removed in order to prevent molten plastic from flowing out of the nozzle, but the back pressure of the injection cylinder cannot be maintained, which leads to the destruction of the supercritical state. A micro-foaming hydraulic control circuit is provided.

[0006] The technical solution adopted by this utility model to solve its technical problem is: a micro-foaming hydraulic control circuit, including an oil tank, a delivery pump, an injection cylinder, and a first three-position four-way directional valve. The input end of the delivery pump is located in the oil tank, and the output end of the delivery pump is connected to the P port of the first three-position four-way directional valve. The A port of the first three-position four-way directional valve is connected to the rodless chamber of the injection cylinder, the B port of the first three-position four-way directional valve is connected to the rod chamber of the injection cylinder, and the T port of the first three-position four-way directional valve is connected to the oil tank. It also includes a circuit switch control mechanism for controlling the nozzle switch. The circuit switch control mechanism includes a control cylinder, an accumulator, a first pressure reducing valve, a second three-position four-way directional valve, a second pressure reducing valve, and a two-position four-way directional valve.

[0007] The output end of the delivery pump is connected to the accumulator, the P port of the first pressure reducing valve, and the P port of the second pressure reducing valve. The A port of the first pressure reducing valve is connected to the P port of the second three-position four-way directional valve. The A port of the second three-position four-way directional valve is connected to the rodless chamber of the control cylinder. The B port of the second three-position four-way directional valve is connected to the rod chamber of the control cylinder. The T port of the second three-position four-way directional valve is connected to the oil tank. The A port of the second pressure reducing valve is connected to the P port of the two-position four-way directional valve. The A port of the two-position four-way directional valve is connected to the external sealing end. The B port of the two-position four-way directional valve is connected to the rod chamber of the injection cylinder. The T port of the two-position four-way directional valve is connected to the oil tank. The set pressure of the first pressure reducing valve is greater than the set pressure of the second pressure reducing valve. Compared to existing technologies, this solution uses a loop switch control mechanism for the nozzle switch. The delivery pump continuously provides the upper limit pressure to the injection cylinder through the loop switch control mechanism. The first three-position four-way reversing valve and the two-position four-way reversing valve work together to control the back pressure. The back pressure setting can be adjusted according to the material characteristics. The injection pressure is controllable and there is no pressure holding process, enabling ordinary injection molding machines to be used in physical foaming applications, thus improving the practicality of ordinary injection molding machines.

[0008] In order to prevent the oil output from the accumulator from flowing back to the delivery pump, in some preferred embodiments, a first check valve is provided on the oil line connecting the delivery pump, the accumulator, and the first pressure reducing valve.

[0009] To facilitate the control of the oil in the circuit, some preferred embodiments also include a two-position two-way directional valve. The P port of the two-position two-way directional valve is located in the oil line connecting the accumulator and the first pressure reducing valve, and the T port of the two-position two-way directional valve is connected to the oil tank.

[0010] In order to ensure that the pressure of the hydraulic oil released by the accumulator is stable and reliable, in some preferred embodiments, a first safety valve is connected between the oil line between the first check valve and the accumulator and the oil tank.

[0011] To ensure stable and reliable pressure throughout the control loop, in some preferred embodiments, a second safety valve is provided between the output end of the delivery pump and the oil tank.

[0012] In order to prevent the oil in the rod chamber of the injection cylinder from flowing back into the oil cylinder, in some preferred embodiments, a second check valve is provided in the oil line between the two-position four-way directional valve and the rod chamber of the injection cylinder. The second check valve is used to prevent the oil in the rod chamber of the injection cylinder from flowing back.

[0013] In order to monitor the oil pressure in the rod chamber of the injection cylinder in real time, in some preferred embodiments, a pressure sensor is installed on the oil line connecting the B port of the first three-position four-way directional valve and the rod chamber of the injection cylinder.

[0014] In order to realize the specific structure of the delivery pump, some preferred embodiments include a main motor and a main pump, wherein the torque output end of the main motor is connected to the power input end of the main pump.

[0015] The beneficial effects of this utility model are as follows: When the micro-foaming hydraulic control circuit of this utility model is in use, the delivery pump continuously provides the upper limit pressure to the injection cylinder through the circuit switch control mechanism of the nozzle switch. The first three-position four-way reversing valve and the two-position four-way reversing valve jointly perform back pressure control. The back pressure setting can be adjusted according to the material characteristics. The injection pressure is controllable and there is no pressure holding process. This realizes the application of physical foaming in ordinary injection molding machines, improves the applicability of ordinary injection molding machines, and avoids the problem that after plasticizing, ordinary injection molding machines require the back pressure of the injection cylinder to be released in order to prevent molten plastic from flowing out of the nozzle. This is because the back pressure of the injection cylinder cannot be maintained, which leads to the destruction of the supercritical state. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Figure 1 This is a schematic diagram of the structure of this utility model.

[0018] In the diagram: 1. Oil tank, 2. Main motor, 3. Main pump, 4. First three-position four-way directional valve, 5. First safety valve, 6. Accumulator, 7. First check valve, 8. Two-position two-way directional valve, 9. Control cylinder, 10. First pressure reducing valve, 11. Second three-position four-way directional valve, 12. Second pressure reducing valve, 13. Two-position four-way directional valve, 14. Second check valve, 15. Injection cylinder, 16. Screw, 17. Plasticizing motor, 18. Pressure sensor, 19. Second safety valve. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to the embodiments:

[0020] This utility model is not limited to the following specific embodiments. Those skilled in the art can implement this utility model using various other specific embodiments based on the disclosed content. Any modifications or alterations to the design structure and concept of this utility model also fall within the protection scope of this utility model. It should be noted that, unless otherwise specified, the embodiments and features described in this utility model can be combined with each other.

[0021] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0022] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0023] like Figure 1 As shown, a micro-foaming hydraulic control circuit includes an oil tank 1, a delivery pump, an injection cylinder 15, a first three-position four-way directional valve 4, and a circuit switch control mechanism. The input end of the delivery pump is located in the oil tank 1, the output end of the delivery pump is connected to the P port of the first three-position four-way directional valve 4, the A port of the first three-position four-way directional valve 4 is connected to the rodless chamber of the injection cylinder 15, the B port of the first three-position four-way directional valve 4 is connected to the rod chamber of the injection cylinder 15, and the T port of the first three-position four-way directional valve 4 is connected to the oil tank 1.

[0024] The loop switch control mechanism includes a control cylinder 9, an accumulator 6, a first pressure reducing valve 10, a second three-position four-way directional valve 11, a second pressure reducing valve 12, and a two-position four-way directional valve 13. The loop switch control mechanism is used to control the nozzle switch. The output end of the delivery pump is connected to the accumulator 6, the P port of the first pressure reducing valve 10, and the P port of the second pressure reducing valve 12, respectively. The A port of the first pressure reducing valve 10 is connected to the P port of the second three-position four-way directional valve 11. The A port of the second three-position four-way directional valve 11 is connected to the rodless chamber of the control cylinder 9, and the B port of the second three-position four-way directional valve 11 is connected to the control cylinder 9. The rod chamber of cylinder 9 is connected; the T port of the second three-position four-way directional valve 11 is connected to the oil tank 1; the A port of the second pressure reducing valve 12 is connected to the P port of the two-position four-way directional valve 13; the A port of the two-position four-way directional valve 13 is connected to the external sealing end; the B port of the two-position four-way directional valve 13 is connected to the rod chamber of injection cylinder 15; the T port of the two-position four-way directional valve 13 is connected to the oil tank 1; the set pressure of the first pressure reducing valve 10 is greater than the set pressure of the second pressure reducing valve 12; the set pressure of the first pressure reducing valve 10 is 70 bar; and the set pressure of the second pressure reducing valve 12 is 50 bar.

[0025] A first check valve 7 is installed on the oil line connecting the delivery pump, accumulator 6, and first pressure reducing valve 10. A second check valve 14 is installed on the oil line between the two-position four-way directional valve 13 and the rod chamber of injection cylinder 15. The second check valve 14 is used to prevent the oil in the rod chamber of injection cylinder 15 from flowing back. A first safety valve 5 is connected between the oil line between the first check valve 7 and accumulator 6 and oil tank 1. A second safety valve 19 is installed between the output end of the delivery pump and oil tank 1.

[0026] It also includes a two-position two-way reversing valve 8, the P port of which is located in the oil line connecting the accumulator 6 and the first pressure reducing valve 10, and the T port of which is connected to the oil tank 1.

[0027] A pressure sensor 18 is installed on the oil line connecting port B of the first three-position four-way directional valve 4 and the rod chamber of the injection cylinder 15.

[0028] The oil pump includes a main motor 2 and a main pump 3. The torque output end of the main motor 2 is connected to the power input end of the main pump 3.

[0029] When the above-mentioned micro-foaming hydraulic control circuit is in use, after the sol is completed, the first three-position four-way directional valve 4 is not energized and is in the middle position. The second three-position four-way directional valve 11 and the two-position four-way directional valve 13 are not energized. The second three-position four-way directional valve 11 is in the middle position and the two-position four-way directional valve 13 is in the right position. Because there is leakage in the middle position of the first three-position four-way directional valve 4, the sol back pressure will be released.

[0030] The micro-foaming control circuit is used during the period from the end of sol-gel production to injection. The main motor 2 starts, the main pump 3 is turned on, the first three-position four-way directional valve 4 is not energized and is in the middle position, and the oil flows through the first one-way valve 7. At this time, the first safety valve 5 is normally closed, the two-position two-way directional valve 8 is energized and is in the left position. At this time, the oil from the two-position two-way directional valve 8 is not flowing. At the same time, the oil flows through the first pressure reducing valve 10, the left side of the second three-position four-way directional valve 11 is energized and is in the left position, and the oil flows through the P port of the second three-position four-way directional valve 11 to the A port and enters the rodless chamber of the control cylinder 9. At this time, the nozzle is closed. The requirements for nozzle closure are high during the process, and the nozzle is monitored and protected by a limit switch.

[0031] When the gel dissolution begins, the main pump 3 supplies oil to the first three-position four-way directional valve 4. The right side of the first three-position four-way directional valve 4 is energized and in the right position. The oil flows through the P port to the A port of the first three-position four-way directional valve 4 and enters the rodless chamber of the injection cylinder 15. The motor drives the screw 16 to dissolve the gel. During the gel dissolution process, the nozzle is closed by the pressure provided by the accumulator 6 to keep the nozzle closed.

[0032] When the sol-gel process is complete, the main pump 3 operates. The first three-position four-way directional valve 4 is de-energized and in the neutral position. The oil flows through the second pressure reducing valve 12, and the two-position four-way directional valve 13 is energized and in the left position. The oil at a pressure of 50 bar flows from port P to port B of the two-position four-way directional valve 13, and then enters the rod chamber of the injection cylinder 15 through the second check valve 14. The second check valve 14 prevents backflow of oil during the process. Meanwhile, the first three-position four-way directional valve 4 mainly performs position and pressure control. Because the first three-position four-way directional valve 4 has a certain opening degree according to pressure fluctuations to ensure dynamic balance, there is a certain amount of leakage in the neutral position of the first three-position four-way directional valve 4. This leakage is monitored by the pressure sensor 18. During the injection process, due to the addition of the micro-foaming control circuit, there will always be back pressure. Then, the injection action will be performed. The main pump 3 will work, and the right side of the second three-position four-way directional valve 11 will be energized and located in the right position. The oil will pass through the P port of the second three-position four-way directional valve 11 to the A port and enter the rod chamber of the control cylinder 9. The oil in the rodless chamber of the control cylinder 9 will pass through the B port of the second three-position four-way directional valve 11 to the T port and flow back to the oil tank 1, thus opening the nozzle. The left side of the first three-position four-way directional valve 4 will be energized and located in the left position. The oil will pass through the P port of the first three-position four-way directional valve 4 to the B port and enter the rod chamber of the injection cylinder 15 for injection. Throughout the process, the second safety valve 19 will play a safety role.

[0033] When shutting down, the motor is de-energized, the main pump 3 stops, the two-position two-way reversing valve 8 loses power and returns to the right position, and the accumulator 6 is depressurized.

[0034] The above description, based on the preferred embodiments of this utility model, provides inspiration. Those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification but must be determined according to the claims.

Claims

1. A micro-foaming hydraulic control circuit, comprising an oil tank (1), a delivery pump, an injection cylinder (15), and a first three-position four-way directional valve (4), wherein the input end of the delivery pump is disposed in the oil tank (1), the output end of the delivery pump is connected to the P port of the first three-position four-way directional valve (4), the A port of the first three-position four-way directional valve (4) is connected to the rodless chamber of the injection cylinder (15), the B port of the first three-position four-way directional valve (4) is connected to the rod chamber of the injection cylinder (15), and the T port of the first three-position four-way directional valve (4) is connected to the oil tank (1), characterized in that: It also includes a loop switch control mechanism for controlling the nozzle switch, the loop switch control mechanism including a control cylinder (9), an accumulator (6), a first pressure reducing valve (10), a second three-position four-way directional valve (11), a second pressure reducing valve (12) and a two-position four-way directional valve (13); The output end of the delivery pump is connected to the accumulator (6), the P port of the first pressure reducing valve (10), and the P port of the second pressure reducing valve (12), respectively. The A port of the first pressure reducing valve (10) is connected to the P port of the second three-position four-way directional valve (11). The A port of the second three-position four-way directional valve (11) is connected to the rodless chamber of the control cylinder (9). The B port of the second three-position four-way directional valve (11) is connected to the rod chamber of the control cylinder (9). 1) The T port of the first pressure reducing valve (10) is connected to the oil tank (1), the A port of the second pressure reducing valve (12) is connected to the P port of the two-position four-way reversing valve (13), the A port of the two-position four-way reversing valve (13) is connected to the external sealing end, the B port of the two-position four-way reversing valve (13) is connected to the rod chamber of the injection cylinder (15), the T port of the two-position four-way reversing valve (13) is connected to the oil tank (1), and the set pressure of the first pressure reducing valve (10) is greater than the set pressure of the second pressure reducing valve (12).

2. A micro-foaming hydraulic control circuit according to claim 1, wherein: A first check valve (7) is provided on the oil line connecting the delivery pump, the accumulator (6), and the first pressure reducing valve (10).

3. A micro-foaming hydraulic control circuit according to claim 2, wherein: It also includes a two-position two-way reversing valve (8), the P port of which is located in the oil line connecting the accumulator (6) and the first pressure reducing valve (10), and the T port of which is connected to the oil tank (1).

4. A micro-foamed hydraulic control circuit according to claim 2 or 3, characterized in that: A first safety valve (5) is connected between the oil line between the first check valve (7) and the accumulator (6) and the oil tank (1).

5. A micro-foaming hydraulic control circuit according to claim 1, wherein: A second safety valve (19) is provided between the output end of the delivery pump and the oil tank (1).

6. A micro-foaming hydraulic control circuit according to claim 1, wherein: A second check valve (14) is provided in the oil line between the two-position four-way directional valve (13) and the rod chamber of the injection cylinder (15). The second check valve (14) is used to prevent the oil in the rod chamber of the injection cylinder (15) from flowing back.

7. A micro-foaming hydraulic control circuit according to claim 1, wherein: A pressure sensor (18) is installed on the oil line connecting the B port of the first three-position four-way directional valve (4) and the rod chamber of the injection cylinder (15).

8. A micro-foaming hydraulic control circuit according to claim 1, wherein: The oil pump includes a main motor (2) and a main pump (3), wherein the torque output end of the main motor (2) is connected to the power input end of the main pump (3).

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