High-pressure pressure-maintaining anti-reflux extrusion injection molding device and operation method

Abstract

The invention provides a high-pressure pressure-maintaining anti-backflow extrusion injection molding device and an operation method, relates to the technical field of screw extruders, and solves the technical problems that a traditional extrusion injection molding device in the prior art is lack of a melt pressurizing injection molding structure and a non-return assembly, so that filling is insufficient, and melt is likely to flow back to the screw extruder. The device comprises a locking type nozzle, a melt pressurizing injection molding structure and a screw extruder, the melt discharging end of the screw extruder is connected with the feeding end of the melt pressurizing injection molding structure, and the discharging end of the melt pressurizing injection molding structure is connected with the locking type nozzle; a check valve is arranged in the feeding end of the melt pressurizing injection molding structure, or a non-return assembly is arranged in the discharging end of the screw extruder; and the non-return valve or the non-return assembly can block a channel at the feeding end of the melt pressurizing injection molding structure or a channel at the discharging end of the screw extruder under the pressure of the reverse flow of the melt.

Description

Technical Field

[0001] The present invention relates to the technical field of screw extruders, and in particular to a high-pressure, pressure-maintaining, and backflow-proof extrusion injection molding device and an operating method, which are specifically applied to the field of socket and spigot molding of large steel-belt reinforced polyethylene double-wall corrugated pipes. Background Art

[0002] The socket of large steel-reinforced polyethylene double-wall corrugated pipe is the core structure of pipe connection, and its molding quality is directly related to the sealing, anti-leakage performance and long-term operation safety of the pipe network system. In existing technology, this type of socket-and-socket joint is primarily produced using extrusion injection molding: plastic melt is injected into the mold cavity under the force of a screw extruder. However, actual production suffers from significant technical deficiencies, particularly in the molding of large socket-and-socket joints. For one thing, the polyethylene melt used in pipes has high viscosity and significant flow resistance, while conventional equipment lacks a melt-boosting injection mechanism. As the size of the socket-and-socket joint increases, the extrusion injection pressure becomes increasingly insufficient, making it difficult to fully push the melt into the mold. Furthermore, conventional structures lack a backflow prevention feature. As injection pressure increases, the melt tends to flow back into the screw extruder, further exacerbating the insufficient injection volume. This is particularly problematic for large socket-and-socket joints, which require large amounts of melt.

[0003] The combination of the above problems leads to large fluctuations in injection pressure and the inability to form stable high pressure, which ultimately causes insufficient melt filling and unstable socket molding, seriously affecting product quality and becoming the main technical obstacle to the production of large sockets. Summary of the Invention

[0004] The present invention aims to provide a high-pressure, pressure-maintaining, anti-backflow extrusion injection molding device and an operating method, so as to overcome the key technical bottlenecks in the existing large-scale steel belt reinforced polyethylene double-wall corrugated pipe socket extrusion injection molding production: the traditional device lacks a melt boosting injection molding structure, resulting in the injection pressure unable to match the high-viscosity polyethylene melt flow requirements and low filling efficiency when the socket specifications are upgraded; and the lack of a backflow prevention component causes the melt to flow back to the screw extruder and the injection amount to decay during the high-pressure injection molding stage. The present invention realizes the directional enhancement of injection pressure and the effective blocking of melt backflow through an integrated structural design and a dynamic pressure control strategy, and ultimately solves the problems of insufficient melt filling and insufficient molding dimensional accuracy, thereby ensuring the molding quality and production stability of large sockets. To achieve the above objectives, the present invention provides the following technical solutions: The present invention provides a high-pressure, pressure-maintaining, and anti-backflow extrusion injection molding device, comprising a locking nozzle, a melt-pressurized injection molding structure, and a screw extruder, wherein the discharge end of the screw extruder is connected to the feed end of the melt-pressurized injection molding structure, and the discharge end of the melt-pressurized injection molding structure is connected to the locking nozzle; A check valve is provided in the feeding end of the melt pressurized injection molding structure, or a check component is provided in the discharging end of the screw extruder; The check valve or the check assembly can block the channel at the inlet end of the melt pressurized injection molding structure or the channel at the outlet end of the screw extruder under the pressure of melt backflow.

[0005] Optionally, the melt pressurized injection molding structure includes an outer cylinder, an inner cylinder, a diverter bracket, and a hydraulic injection assembly, wherein both ends of the outer cylinder are respectively connected to the locking nozzle and the screw extruder, the inner cylinder and the check valve are both located in the outer cylinder, the inner cylinder and the outer cylinder are connected via the diverter bracket, and a diverter channel exists between the inner cylinder and the outer cylinder, the blocking end of the inner cylinder is connected to the check valve, and the diverter bracket is close to the check valve, and the hydraulic injection assembly is installed in the inner cylinder; A partition plate is provided in the inner cylinder, which divides the interior of the inner cylinder into a storage chamber and a accommodating chamber. The hydraulic injection assembly is located in the accommodating chamber. The storage chamber is close to the locking nozzle. The front side wall of the inner cylinder is provided with multiple flow openings. The diversion channel is connected to the storage chamber through the flow openings. The storage chamber is close to the locking nozzle.

[0006] Optionally, the check valve includes a valve body head, a valve body frame and a check ring, one end of the valve body frame is fixedly connected to the valve body head, the valve body head is close to the screw extruder, and the other end of the valve body frame is plugged into the sealing end of the inner cylinder, the check ring is sleeved on the valve body frame and a feed channel is provided between the check ring and the valve body frame, the outer wall of the check ring is in contact with the inner wall of the outer cylinder, the diameter of the connecting end of the valve body head is larger than the outer diameter of the valve body frame, and the check ring can block the channel between the valve body head and the outer cylinder.

[0007] Optionally, the end ring diameter of the check ring is larger than the distance between the valve body head and the outer cylinder, and the inner ring diameter of the check ring near the front end of the valve body head is smaller than the inner ring diameter of the check ring near the rear end of the diverter bracket.

[0008] Optionally, a circumferential groove is provided on the outer wall of the valve body frame, and a heat insulation cavity is provided inside the valve body frame.

[0009] Optionally, the hydraulic injection assembly includes a cylinder body, a piston rod, a piston head and a push plug, wherein the cylinder body is installed in the accommodating cavity, the piston head is located in the cylinder body, the push plug is located in the storage cavity, one end of the piston rod is connected to the piston head, and the other end of the piston rod passes through the partition plate and is connected to the push plug; The piston head divides the cylinder into a first cavity and a second cavity. The melt pressurized injection structure is provided with a first hydraulic channel and a second hydraulic channel. The first cavity is connected to the first hydraulic channel, and the second cavity is connected to the second hydraulic channel.

[0010] Optionally, the melt pressurized injection molding structure further includes a spiral water jacket, on which a first cooling channel and a second cooling channel are provided. The spiral water jacket is sleeved on the outer wall of the cylinder body, and a spiral channel is provided on the inner wall of the spiral water jacket. One end of the spiral channel is connected to the first cooling channel, and the other end of the spiral channel is connected to the second cooling channel. An insulating gap is provided between the spiral water jacket and the inner cylinder body.

[0011] Optionally, the melt pressurized injection molding structure further includes a melt metering module, and the melt metering module is used to measure the amount of melt in the storage cavity; The melt metering module includes a laser rangefinder and a laser reflection panel. The laser rangefinder is mounted on the partition plate, and the laser reflection panel is mounted on the push plug.

[0012] Optionally, it also includes a control device, a frame and a pressure detection unit, the control device and the screw extruder are both installed on the frame, the detection end of the pressure detection unit is embedded in the storage cavity, and the pressure detection unit and the screw extruder are both electrically connected to the control device.

[0013] The present invention provides an operating method for a high-pressure, pressure-maintaining, and anti-backflow extrusion injection molding device, comprising the following operating steps: Step S1, initial stage: before the high-pressure pressure-maintaining anti-backflow extrusion injection molding device is started, all components are in a standby state, the screw extruder is not started, and there is no melt in the storage chamber; Step S2, pre-plasticization stage: the locking nozzle is closed, and the melt is then conveyed to the storage chamber in the melt pressurized injection molding structure through the screw extruder. At this time, the check valve is in an open state under the pressure of the forward flow of the melt, and the melt metering module measures the amount of melt in the storage chamber in real time and transmits it to the control device; Step S3, injection stage: when the control device determines that the amount of melt in the storage chamber reaches a preset value, the control device controls the screw extruder to stop conveying the melt, opens the locking nozzle and controls the hydraulic system to inject hydraulic oil into the first cavity in the hydraulic injection assembly, and the push plug moves forward under the push of the hydraulic oil, and injects the melt in the storage chamber into the mold through the locking nozzle; at the same time, the check ring moves backward under the pressure of the melt backflow, blocking the channel at the feed end of the melt pressurized injection molding structure; Step S4, pressure holding stage: After the mold is filled, the hydraulic system maintains the pressure in the hydraulic injection assembly, and the pressure detection unit monitors the pressure in the storage chamber in real time and dynamically adjusts the hydraulic oil supply until the melt cools and solidifies; Step S5, reset phase: 5.1. Push Plug Reset Control: The control device instructs the hydraulic system to switch the oil supply direction, injecting hydraulic oil into the second chamber through the second hydraulic channel, pushing the piston head away from the locking nozzle. The piston rod simultaneously drives the push plug backward until the laser rangefinder detects that the push plug has returned to its initial position. At this time, the volume of the storage chamber is restored to its maximum state. 5.2. Subsequent operation: If it is a single production mode, the device is shut down and the remaining material in the storage chamber is cleaned; if continuous production is required, the shutdown step can be skipped and the next cycle of pre-plasticization can be directly entered.

[0014] The present invention provides a high-pressure, pressure-maintaining, and anti-backflow extrusion and injection molding device, in which a melt-pressurizing injection molding structure is connected between a locking nozzle and a screw extruder, and the screw extruder is used to convey the melt to the melt-pressurizing injection molding structure, and the melt-pressurizing injection molding structure is used to control the injection pressure of the melt, and the locking nozzle is used to inject the melt. When working, the screw extruder conveys the melt to the melt-pressurizing injection molding structure, and the check valve or the check component is in an open state under the pressure of the forward fluid, so that the melt in the screw extruder can enter the melt-pressurizing injection molding structure, and then the melt-pressurizing injection molding structure controls the injection pressure of the locked nozzle. When the nozzle is injecting, the check valve or check component is in a closed state under the action of backflow pressure, thereby preventing part of the melt in the melt-pressurized injection molding structure from flowing back into the screw extruder, and instead entering the locked nozzle, thereby realizing extrusion injection molding. In this process, the use of the melt-pressurized injection molding structure can effectively control the injection pressure and achieve precise constant pressure plastic replenishment, thereby ensuring production quality and production efficiency, and solving the technical problems in the conventional extrusion injection molding device in the prior art that lacks a melt-pressurized injection molding structure and a check component, resulting in insufficient filling and easy reflux of the melt to the screw extruder. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 This is a schematic structural diagram of a high-pressure, pressure-maintaining, and backflow-proof extrusion injection molding device provided by an embodiment of the present invention; Figure 2This is a cross-sectional view of a melt pressurization injection molding structure of a high-pressure, pressure-maintaining, and backflow-proof extrusion injection molding device provided by an embodiment of the present invention in an open state; Figure 3 It is a cross-sectional view of the closed state of the melt pressurization injection molding structure of a high-pressure pressure-maintaining and backflow-proof extrusion injection molding device provided by an embodiment of the present invention.

[0017] 1. Locking nozzle; 2. Melt pressurized injection molding structure; 21. Check valve; 211. Valve head; 212. Valve frame; 213. Check ring; 22. Outer cylinder; 23. Inner cylinder; 231. Separator; 232. Storage chamber; 233. Accommodation chamber; 234. Flow port; 24. Diverter bracket; 25. Hydraulic injection assembly; 251. Cylinder; 252. Piston rod; 253. Piston head; 254. Push plug; 255. First cavity; 256. Second cavity; 26. Spiral water jacket; 3. Screw extruder; 4. The first hydraulic channel; 5. Second hydraulic channel; 6. The first cooling channel; 7. Second cooling channel; 8. Control device; 9. Frame; 10. Pressure detection unit. DETAILED DESCRIPTION

[0018] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.

[0019] In the description of the present invention, it should be noted that, unless otherwise specified, the term "plurality" means two or more. Terms such as "upper," "lower," "left," "right," "inner," "outer," "front," "rear," "head," and "tail" are used to indicate positions or relationships based on those shown in the accompanying drawings. These terms are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; and direct or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in the present invention depending on the specific circumstances.

[0021] The present invention provides a high-pressure, pressure-maintaining, and backflow-proof extrusion and injection molding device, comprising a locking nozzle 1, a melt-pressurized injection molding structure 2, and a screw extruder 3, wherein the discharge end of the screw extruder 3 is connected to the feed end of the melt-pressurized injection molding structure 2, and the discharge end of the melt-pressurized injection molding structure 2 is connected to the locking nozzle 1; A check valve 21 is provided in the feed end of the melt-boosting injection molding structure 2, or a check assembly is provided in the discharge end of the screw extruder 3; the check valve 21 or the check assembly can block the channel at the feed end of the melt-boosting injection molding structure 2 or the channel at the discharge end of the screw extruder 3 under the pressure of the melt backflow. The present invention provides a high-pressure pressure-maintaining anti-backflow extrusion injection molding device, in which the melt-boosting injection molding structure 2 is connected between the locking nozzle 1 and the screw extruder 3, the screw extruder 3 is used to transport the melt to the melt-boosting injection molding structure 2, the melt-boosting injection molding structure 2 is used to control the injection pressure of the melt, the locking nozzle 1 is used to inject the melt, and when working, the screw extruder 3 transports the melt to the melt-boosting injection molding structure 2, and the check valve or the check assembly is in an open state under the pressure of the forward fluid, so that the melt in the screw extruder 3 can enter the melt-boosting injection molding structure 2, and then the melt-boosting injection molding structure 2 is injected. When the locked nozzle 1 is injected, the check valve or check component is in a closed state under the action of the backflow pressure, thereby preventing part of the melt in the melt-boosting injection molding structure 2 from flowing back into the screw extruder 3, and instead entering the locked nozzle 1, thereby realizing extrusion injection molding. In this process, the melt-boosting injection molding structure 2 is adopted, which can effectively control the injection pressure and realize precise constant pressure plastic replenishment, thereby ensuring production quality and production efficiency, and solving the technical problems in the conventional extrusion injection molding device in the prior art that lacks a melt-boosting injection molding structure and a check component, resulting in insufficient filling and easy reflux of the melt to the screw extruder.

[0022] As an optional embodiment, the melt pressurized injection molding structure 2 includes an outer cylinder 22, an inner cylinder 23, a diverter bracket 24 and a hydraulic injection assembly 25. The two ends of the outer cylinder 22 are respectively connected to the locking nozzle 1 and the screw extruder 3, and are sealed and docked. The inner cylinder 23 and the check valve 21 are both located in the outer cylinder 22. The inner cylinder 23 and the outer cylinder 22 are connected through the diverter bracket 24 and there is a diverter channel between the inner cylinder 23 and the outer cylinder 22. The front end of the inner cylinder 23 cooperates with the front end inner wall of the outer cylinder 22. The blocking end of the inner cylinder 23 is connected to the check valve 21 and the diverter bracket 24 is close to the check valve 21. A plurality of circumferentially distributed diverter ports are provided on the diverter bracket 24, and the hydraulic injection assembly 25 is installed in the inner cylinder 23. A partition plate 231 is provided within the inner cylinder 23, dividing the interior of the inner cylinder 23 into a storage chamber 232 and a receiving chamber 233. The hydraulic injection assembly 25 is located in the receiving chamber 233. The storage chamber 232 is adjacent to the locking nozzle 1. The front sidewall of the inner cylinder 23 is provided with multiple flow openings 234. The diverter channel communicates with the storage chamber 232 through the flow openings 234. The storage chamber 232 is adjacent to the locking nozzle 1. The melt conveyed by the screw extruder 3 passes through the channel formed by the check valve, the diverter channel, and the flow openings 234 in sequence, and finally enters the storage chamber 232.

[0023] As an optional embodiment, the check valve 21 includes a valve body head 211, a valve body frame 212 and a check ring 213. One end of the valve body frame 212 is fixedly connected to the valve body head 211. The valve body head 211 is close to the screw extruder 3. The end of the valve body head 211 close to the screw extruder 3 is a conical structure or a spherical structure, which can effectively convert the melt into an annular melt. The other end of the valve body frame 212 is plugged into the sealing end of the inner cylinder 23. The check ring 213 is sleeved on the valve body frame 212 and a feed channel is provided between the check ring 213 and the valve body frame 212. The outer wall of the check ring 213 contacts the inner wall of the outer cylinder 22. The diameter of the connecting end of the valve body head 211 is larger than the outer diameter of the valve body frame 212. The check ring 213 can block the channel between the valve body head 211 and the outer cylinder 22 , the check ring 213 can move on the valve body frame 212 under the action of fluid pressure, thereby realizing the opening and closing of the check valve 21; when the melt in the screw extruder 3 is transported to the melt pressurized injection molding structure 2, the positive pressure of the melt will push the check ring 213 to move in the direction close to the diversion bracket 24, thereby moving away from the valve body head 211, so that the melt can pass through the channel between the valve body head 211 and the outer cylinder 22, and then pass through the feed channel and flow into the diversion channel; when the hydraulic injection assembly 25 pushes the melt in the storage cavity 232, the pressure of the melt backflow will push the check ring 213 to move in the direction close to the valve body head 211, so that the check ring 213 will block the channel between the valve body head 211 and the outer cylinder 22, thereby preventing the melt from flowing into the screw extruder 3.

[0024] As an optional implementation, the end ring diameter of the check ring 213 is larger than the distance between the valve body head 211 and the outer cylinder 22, and the inner ring diameter of the front end of the check ring 213 near the valve body head 211 is smaller than the inner ring diameter of the rear end of the check ring 213 near the diverter bracket 24, so that the check ring 213 can block the channel between the valve body head 211 and the outer cylinder 22. A circumferential groove is provided on the outer wall of the valve body frame 212. The circumferential groove is to avoid the inner wall of the end of the check ring 213 to prevent the outer wall of the valve body frame 212 from fitting with the inner wall of the check ring 213, resulting in a reduction or blockage of the opening of the feed channel. An insulating cavity is provided inside the valve body frame 212, which can effectively reduce the contact area, thereby playing a role in heat insulation.

[0025] As an optional embodiment, the hydraulic injection assembly 25 includes a cylinder body 251, a piston rod 252, a piston head 253 and a push plug 254. The cylinder body 251 is installed in the accommodating chamber 233, the piston head 253 is located in the cylinder body 251, and the push plug 254 is located in the storage chamber 232. One end of the piston rod 252 is connected to the piston head 253, and the other end of the piston rod 252 passes through the partition plate 231 and is connected to the push plug 254. The piston head 253 separates the cylinder body 251 into a first cavity 255 and a second cavity 256. The melt pressurized injection structure 2 is provided with a first hydraulic channel 4 and a second hydraulic channel 5. The first cavity 255 is connected to the first hydraulic channel 4, and the second cavity 256 is connected to the second hydraulic channel 5. The hydraulic system is connected to the first hydraulic channel 4 and the second hydraulic channel 5 respectively. When the melt in the storage cavity 232 needs to be injected into the locking nozzle 1, the hydraulic system transports hydraulic oil to the first hydraulic channel 4 and enters the first cavity 255, thereby pushing the piston head 253 to move in the direction close to the locking nozzle 1, and then The push plug 254 is pushed to move toward the locked nozzle 1, so that the melt in the storage chamber 232 enters the locked nozzle 1 under the push of the push plug 254, and the hydraulic oil in the second cavity 256 will flow back to the hydraulic system through the second hydraulic channel 5; when the injection is completed, the hydraulic system transports hydraulic oil to the second hydraulic channel 5 and enters the second cavity 256, thereby pushing the piston head 253 to move away from the locked nozzle 1, and the hydraulic oil in the first cavity 255 will flow back to the hydraulic system through the first hydraulic channel 4, and the push plug 254 will return to its original position, waiting for the next work.

[0026] As an optional embodiment, the melt pressurized injection molding structure 2 further includes a spiral water jacket 26. A first cooling channel 6 and a second cooling channel 7 are provided on the melt pressurized injection molding structure 2. The spiral water jacket 26 is sleeved on the outer wall of the cylinder body 251. The inner wall of the spiral water jacket 26 is provided with a spiral channel. One end of the spiral channel is connected to the first cooling channel 6, and the other end of the spiral channel is connected to the second cooling channel 7. An insulating gap is provided between the spiral water jacket 26 and the inner cylinder body 23. The first cooling channel 6 and the second cooling channel 7 are connected to the cooling system, so that the spiral channel, the first cooling channel 6, the second cooling channel 7 and the cooling system form a cooling circulation loop, thereby cooling the hydraulic injection assembly 25.

[0027] As an optional embodiment, the melt pressurized injection molding structure 2 also includes a melt metering module, which is used to measure the amount of melt in the storage chamber 232, and the melt metering module is electrically connected to the control device 8; the melt metering module includes a laser rangefinder and a laser reflection panel, the laser rangefinder is installed on the partition plate 231, and the laser reflection panel is installed on the push plug 254, and the amount of melt in the storage chamber 232 is detected and calculated by moving the push plug 254.

[0028] As an optional embodiment, it also includes a control device 8, a frame 9 and a pressure detection unit 10. The control device 8 and the screw extruder 3 are both installed on the frame 9. The detection end of the pressure detection unit 10 is embedded in the storage chamber 232. The pressure detection unit 10 and the screw extruder 3 are both electrically connected to the control device 8. The pressure detection unit 10 is used to detect the pressure in the storage chamber 232.

[0029] The present invention provides an operating method for a high-pressure, pressure-maintaining, and anti-backflow extrusion injection molding device, comprising the following operating steps: Step S1, initial stage: before the high-pressure pressure-maintaining anti-backflow extrusion injection molding device is started, all components are in a standby state, the screw extruder 3 is not started, and there is no melt in the storage chamber 232; Step S2, pre-molding stage: the locking nozzle 1 is closed, and the melt is then conveyed to the storage chamber 232 in the melt-pressurized injection molding structure 2 through the screw extruder 3. At this time, the check valve 21 is in an open state under the pressure of the forward flow of the melt. The melt metering module measures the amount of melt in the storage chamber 232 in real time and transmits it to the control device 8; Step S3, injection stage: When the control device 8 determines that the amount of melt in the storage chamber 232 reaches a preset value, the control device 8 controls the screw extruder 3 to stop conveying the melt, opens the locking nozzle 1, and controls the hydraulic system to inject hydraulic oil into the first cavity 255 in the hydraulic injection assembly 25. The push plug 254 moves forward under the push of the hydraulic oil and injects the melt in the storage chamber 232 into the mold through the locking nozzle 1. At the same time, the check ring 213 moves backward under the pressure of the melt backflow, blocking the channel at the feed end of the melt pressurized injection molding structure 2. Step S4, pressure holding stage: After the mold is filled, the hydraulic system maintains the pressure in the hydraulic injection assembly 25, and the pressure detection unit 10 monitors the pressure in the storage chamber 232 in real time and dynamically adjusts the hydraulic oil supply until the melt cools and solidifies; Step S5, reset phase: 5.1. Push plug reset control: The control device 8 instructs the hydraulic system to switch the oil supply direction, stops supplying oil to the first hydraulic channel 4 and opens the oil return path, and at the same time injects hydraulic oil into the second cavity 256 through the second hydraulic channel 5; the injected hydraulic oil forms a thrust in the second cavity 256, pushing the piston head 253 to move away from the locked nozzle 1; because the two ends of the piston rod 252 are fixedly connected to the piston head 253 and the push plug 254 respectively, when the piston head 253 moves, the piston rod 252 synchronously drives the push plug 254 to retreat along the inner wall of the storage chamber 232; the laser rangefinder monitors the position of the push plug 254 in real time, and when it detects that the distance between the push plug 254 and the partition plate 231 has returned to the initial value of the pre-plasticization stage (i.e., returned to the initial position), it sends an in-position signal to the control device 8, and the control device 8 instructs the hydraulic system to stop supplying oil. At this time, the volume of the storage chamber 232 is restored to its maximum state; 5.2. Subsequent operations: After completing the above-mentioned reset operation, if it is a single production mode, the device executes the shutdown procedure, and the operator cleans the remaining material inside the storage chamber 232; if it is a continuous production mode, the control device 8 directly triggers the pre-plasticization stage start instruction, and enters step S2 of the next cycle without stopping, thereby realizing continuous operation of the production process. The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A high-pressure, pressure-maintaining, anti-backflow extrusion injection molding device, characterized in that: It comprises a locking nozzle (1), a melt pressurized injection molding structure (2) and a screw extruder (3), wherein: The discharge end of the screw extruder (3) is connected to the feed end of the melt pressurized injection molding structure (2), and the discharge end of the melt pressurized injection molding structure (2) is connected to the locking nozzle (1); A check valve (21) is provided in the feed end of the melt pressurized injection molding structure (2), or a check component is provided in the discharge end of the screw extruder (3); The check valve (21) or the check component can block the channel at the feed end of the melt pressurized injection molding structure (2) or the channel at the discharge end of the screw extruder (3) under the pressure of melt backflow.

2. A high-pressure, pressure-maintaining, anti-backflow extrusion injection molding device according to claim 1, characterized in that: The melt pressurized injection molding structure (2) comprises an outer cylinder (22), an inner cylinder (23), a diverter bracket (24) and a hydraulic injection assembly (25), the two ends of the outer cylinder (22) are respectively connected to the locking nozzle (1) and the screw extruder (3), the inner cylinder (23) and the check valve (21) are both located in the outer cylinder (22), the inner cylinder (23) and the outer cylinder (22) are connected through the diverter bracket (24), and a diverter channel exists between the inner cylinder (23) and the outer cylinder (22), the blocking end of the inner cylinder (23) is connected to the check valve (21), and the diverter bracket (24) is close to the check valve (21), and the hydraulic injection assembly (25) is installed in the inner cylinder (23); A partition plate (231) is provided in the inner cylinder (23), and the partition plate (231) divides the interior of the inner cylinder (23) into a storage chamber (232) and an accommodating chamber (233). The hydraulic injection assembly (25) is located in the accommodating chamber (233). The storage chamber (232) is close to the locking nozzle (1). A plurality of flow openings (234) are provided on the front side wall of the inner cylinder (23). The diversion channel is connected to the storage chamber (232) through the flow openings (234). The storage chamber (232) is close to the locking nozzle (1).

3. A high-pressure, pressure-maintaining, anti-backflow extrusion injection molding device according to claim 2, characterized in that: The check valve (21) includes a valve body head (211), a valve body frame (212) and a check ring (213), one end of the valve body frame (212) is fixedly connected to the valve body head (211), the valve body head (211) is close to the screw extruder (3), the other end of the valve body frame (212) is plug-connected to the blocking end of the inner cylinder (23), the check ring (213) is sleeved on the valve body frame (212), and a feed channel is provided between the check ring (213) and the valve body frame (212), the outer wall of the check ring (213) is in contact with the inner wall of the outer cylinder (22), the diameter of the connecting end of the valve body head (211) is larger than the outer diameter of the valve body frame (212), and the check ring (213) can block the channel between the valve body head (211) and the outer cylinder (22).

4. A high-pressure, pressure-maintaining, anti-backflow extrusion injection molding device according to claim 3, characterized in that: The end ring diameter of the check ring (213) is larger than the distance between the valve body head (211) and the outer cylinder (22), and the inner ring diameter of the check ring (213) near the front end of the valve body head (211) is smaller than the inner ring diameter of the check ring (213) near the rear end of the diverter bracket (24).

5. The high-pressure, pressure-maintaining, anti-backflow extrusion injection molding device according to claim 3, characterized in that: A circumferential groove is provided on the outer wall of the valve body frame (212), and a heat insulation cavity is provided inside the valve body frame (212).

6. The high-pressure, pressure-maintaining, anti-backflow extrusion injection molding device according to claim 2, characterized in that: The hydraulic injection assembly (25) comprises a cylinder body (251), a piston rod (252), a piston head (253) and a push plug (254); the cylinder body (251) is installed in the accommodating cavity (233); the piston head (253) is located in the cylinder body (251); the push plug (254) is located in the storage cavity (232); one end of the piston rod (252) is connected to the piston head (253); the other end of the piston rod (252) passes through the partition plate (231) and is connected to the push plug (254); The piston head (253) divides the cylinder body (251) into a first cavity (255) and a second cavity (256); a first hydraulic channel (4) and a second hydraulic channel (5) are provided on the melt pressurization injection molding structure (2); the first cavity (255) is connected to the first hydraulic channel (4), and the second cavity (256) is connected to the second hydraulic channel (5).

7. The high-pressure, pressure-maintaining, anti-backflow extrusion injection molding device according to claim 6, characterized in that: The melt pressurized injection molding structure (2) further includes a spiral water jacket (26). A first cooling channel (6) and a second cooling channel (7) are provided on the melt pressurized injection molding structure (2). The spiral water jacket (26) is sleeved on the outer wall of the cylinder body (251). A spiral channel is provided on the inner wall of the spiral water jacket (26). One end of the spiral channel is connected to the first cooling channel (6), and the other end of the spiral channel is connected to the second cooling channel (7). A heat insulating gap is provided between the spiral water jacket (26) and the inner cylinder body (23).

8. The high-pressure, pressure-maintaining, anti-backflow extrusion injection molding device according to claim 6, characterized in that: The melt pressurized injection molding structure (2) further includes a melt metering module, and the melt metering module is used to measure the amount of melt in the storage cavity (232); The melt metering module comprises a laser rangefinder and a laser reflection panel, wherein the laser rangefinder is mounted on the partition plate (231) and the laser reflection panel is mounted on the push plug (254).

9. The high-pressure, pressure-maintaining, anti-backflow extrusion injection molding device according to claim 2, characterized in that: It also includes a control device (8), a frame (9) and a pressure detection unit (10), wherein the control device (8) and the screw extruder (3) are both mounted on the frame (9), a detection end of the pressure detection unit (10) is embedded in the storage cavity (232), and the pressure detection unit (10) and the screw extruder (3) are both electrically connected to the control device (8).

10. An operating method comprising the high-pressure, pressure-maintaining, and anti-backflow extrusion injection molding device according to any one of claims 1 to 9, characterized in that: The following steps are included: Step S1, initial stage: before the high-pressure pressure-maintaining anti-backflow extrusion injection molding device is started, all components are in a standby state, the screw extruder (3) is not started, and there is no melt in the storage chamber (232); Step S2, pre-molding stage: the locking nozzle (1) is closed, and the melt is then conveyed to the storage chamber (232) in the melt pressurized injection molding structure (2) through the screw extruder (3). At this time, the check valve (21) is in an open state under the pressure of the forward flow of the melt, and the melt metering module measures the amount of melt in the storage chamber (232) in real time and transmits it to the control device (8); Step S3, injection stage: when the control device (8) determines that the amount of melt in the storage cavity (232) reaches a preset value, the control device (8) controls the screw extruder (3) to stop conveying the melt, opens the locking nozzle (1) and controls the hydraulic system to inject hydraulic oil into the first cavity (255) in the hydraulic injection assembly (25), and the push plug (254) moves forward under the push of the hydraulic oil, and injects the melt in the storage cavity (232) into the mold through the locking nozzle (1); at the same time, the check ring (213) moves backward under the pressure of the melt backflow, blocking the channel at the feed end of the melt pressurized injection molding structure (2); Step S4, pressure holding stage: after the mold is filled, the hydraulic system maintains the pressure in the hydraulic injection assembly (25), and the pressure detection unit (10) monitors the pressure in the storage cavity (232) in real time, and dynamically adjusts the hydraulic oil supply until the melt is cooled and solidified; Step S5, reset phase: 5.

1. Push plug reset control: the control device (8) instructs the hydraulic system to switch the oil supply direction, injects hydraulic oil into the second cavity (256) through the second hydraulic channel (5), and pushes the piston head (253) to move away from the locking nozzle (1); the piston rod (252) synchronously drives the push plug (254) to retreat until the laser rangefinder detects that the push plug (254) has returned to its initial position, at which time the volume of the storage cavity (232) is restored to its maximum state; 5.

2. Subsequent operation: If it is a single production mode, the device is shut down and the remaining material in the storage chamber (232) is cleaned; If continuous production is required, the shutdown step can be skipped and the next cycle can be directly entered into the pre-plasticization stage.

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