Physical micro-foaming screw structure, physical micro-foaming device and injection molding machine

Abstract

The utility model belongs to physical micro -foaming technical field discloses physical micro -foaming screw structure, physical micro -foaming device and injection molding machine. Physical micro -foaming screw structure is located in the melt glue cylinder with the injection hole, is divided into assembly section, plasticizing section, check section, mixing section in proper order along material conveying direction, and the drive mechanism is connected with assembly section to drive its rotation, and material is heated into melt through plasticizing section. The spherical check valve of check section contains main part, link part, check ball, and the both ends of main part are respectively detachable and connect link part, plasticizing section output end, and the other end of link part is detachable and connects mixing section input end, check ball is in the accommodating cavity surrounded by main part and link part, melt passes through main part communication hole, first runner to check ball, and passes through link part second runner and flows to mixing section, and injection hole corresponds mixing section input end, makes supercritical fluid mix with melt, and check ball can adhere to first runner port and restricts melt counterflow. This structure reduces melt backflow, and it is convenient and quick to replace parts.

Description

Technical Field

[0001] This utility model relates to the field of physical micro-foaming technology, and in particular to a physical micro-foaming screw structure, a physical micro-foaming device, and an injection molding machine. Background Technology

[0002] In physical microfoaming injection molding technology, a physical microfoaming screw structure is set in a melt cylinder with air injection holes. A drive mechanism can drive the physical microfoaming screw structure to rotate. The physical microfoaming screw structure includes a plasticizing section, a supercritical fluid injection section, and a mixing section connected in sequence. The plastic is heated to a molten state in the plasticizing section to serve as the matrix. The supercritical fluid, as a foaming agent, is injected into the matrix through the air injection holes to achieve initial diffusion between the supercritical fluid and the melt. The mixing section is used to forcibly shear the melt, break up large bubbles, promote molecular-level diffusion of the supercritical fluid, and form a homogeneous solution. The final product contains a large number of extremely small, uniformly distributed closed-cell structures (usually at the micrometer level, ranging from 1 micrometer to 100 micrometers, with the average diameter limited to within 50 micrometers as much as possible).

[0003] Currently, during use, the melt is prone to backflow and poor sealing when flowing from the plasticizing section to the mixing section, affecting the stability of the injection endpoint. When replacing, the length-to-diameter ratio of the physical micro-foaming screw structure is generally 24:1 or higher, and the size is relatively long. Therefore, the overall melt barrel often needs to be matched with a longer size to ensure that there is enough space to pull the physical micro-foaming screw structure out of the melt barrel for replacement.

[0004] Therefore, there is an urgent need for physical micro-foaming screw structures, physical micro-foaming devices, and injection molding machines to solve the above problems. Utility Model Content

[0005] The first objective of this invention is to provide a physically micro-foamed screw structure that reduces melt backflow and improves injection stability during use. When changing screws, it allows for convenient and quick replacement of the physically micro-foamed screw structure, thereby improving production efficiency.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] A physical micro-foaming screw structure is disposed inside a melt cylinder. The melt cylinder is provided with an injection port, which can be connected to an external injection mechanism to inject supercritical fluid into the melt cylinder. The physical micro-foaming screw structure includes an assembly section, a plasticizing section, a check section, and a mixing section connected sequentially along the material conveying direction. The assembly section can be connected to the output end of an external drive mechanism to drive the physical micro-foaming screw structure to rotate as a whole. The material is heated in the plasticizing section to form a melt.

[0008] The check valve section is equipped with a spherical check valve, which includes a main body, a connecting part, and a check ball. The first end of the main body and the first end of the connecting part are detachably connected. The second end of the main body is detachably connected to the output end of the plasticizing section, and the second end of the connecting part is detachably connected to the input end of the mixing section. The air injection hole is correspondingly provided with the input end of the mixing section so that the supercritical fluid can mix with the melt in the mixing section. The check ball is disposed in the receiving cavity formed by the main body and the connecting part. The main body has a connecting hole on its outer periphery, and the main body has a first flow channel communicating with the connecting hole. The connecting part has a second flow channel communicating with the first flow channel.

[0009] The melt flowing out of the output end of the plasticizing section passes through the connecting hole and the first flow channel to the check ball, and then flows through the second flow channel to the mixing section. The check ball can fit with the port of the first flow channel to restrict the melt from flowing in the opposite direction of the material conveying.

[0010] As an alternative solution for a physically micro-foamed screw structure, the working outer diameter of the main body is consistent with the working outer diameter of the plasticizing section, and the working outer diameter of the connecting part is consistent with the working outer diameter of the mixing section.

[0011] As an alternative solution for a physical micro-foamed screw structure, the first end of the main body is provided with a first external thread, and the first end of the connecting part is provided with a first internal thread that mates with the first external thread, so that the first end of the main body and the first end of the connecting part are detachably threadedly connected.

[0012] As an alternative solution for a physical micro-foamed screw structure, the main body is provided with a first positioning port and the connecting part is provided with a second positioning port. The first positioning port and the second positioning port can be connected by shape adaptation to form a positioning fit. When the main body and the connecting part are threadedly connected, the relative positions of the main body and the connecting part in the circumferential and axial directions are defined.

[0013] As an alternative solution for a physical micro-foaming screw structure, the second end of the main body is provided with a second external thread, and the output end of the plasticizing section is provided with a second internal thread that mates with the second external thread, so that the second end of the main body and the output end of the plasticizing section are detachably threadedly connected; the second end of the connecting part is provided with a third external thread, and the input end of the mixing section is provided with a third internal thread that mates with the third external thread, so that the second end of the connecting part and the input end of the mixing section are detachably threadedly connected.

[0014] As an alternative solution for a physically micro-foamed screw structure, the mixing section is provided with multiple screw rib groups spaced apart along its axial direction. Each screw rib group includes a first screw rib, a second screw rib, a third screw rib, and a fourth screw rib arranged sequentially along its axial direction. The first screw rib and the third screw rib are grooveless structures. The second screw rib is provided with multiple first grooves in the circumferential direction, and the fourth screw rib is provided with multiple second grooves in the circumferential direction. The first grooves and the second grooves are distributed alternately.

[0015] As an alternative solution for a physically micro-foamed screw structure, the plasticizing section includes a feeding section, a compression section, and a metering section connected sequentially along the material conveying direction. The feeding section is used to convey solid material particles; the compression section is used to compact and melt the material; the metering section is used to homogenize the temperature and viscosity of the melt, enhance the shearing effect on the melt, and provide a stable pressure environment for subsequent supercritical fluid injection. The output end of the metering section is detachably connected to the second end of the main body.

[0016] As an alternative solution for a physically micro-foamed screw structure, the bottom diameter of the feeding section is fixed, the thread depth of the feeding section is fixed and is the largest in the plasticizing section; the bottom diameter of the compression section gradually increases along the material conveying direction, so that the thread depth of the compression section gradually decreases along the material conveying direction; the bottom diameter of the metering section is fixed, the thread depth of the metering section is fixed and is smaller than the thread depth of the feeding section and the compression section, and is the smallest in the plasticizing section.

[0017] The second objective of this invention is to provide a physical micro-foaming device that employs the aforementioned physical micro-foaming screw structure to ensure thorough mixing of the melt and supercritical fluid, reduce melt backflow, and improve the operational stability of the physical micro-foaming device.

[0018] To achieve this objective, the present invention adopts the following technical solution:

[0019] A physical microfoaming device includes a melt cylinder, an injection mechanism, a drive mechanism, and the aforementioned physical microfoaming screw structure. The physical microfoaming screw structure is disposed in the melt cylinder, which provides space for material conveying, melting, mixing, and foaming. The melt cylinder is provided with an injection hole, which is correspondingly disposed to the input end of the mixing section of the physical microfoaming screw structure and can be connected to the injection mechanism for injecting supercritical fluid into the melt cylinder. The output end of the drive mechanism is connected to the assembly section of the physical microfoaming screw structure to drive the physical microfoaming screw structure to rotate.

[0020] The third objective of this invention is to provide an injection molding machine that employs the aforementioned physical micro-foaming device to reduce melt backflow, improve injection stability, reduce processing and maintenance costs, and shorten emergency response time.

[0021] To achieve this objective, the present invention adopts the following technical solution:

[0022] The injection molding machine includes a nozzle and the aforementioned physical micro-foaming device. The output end of the melt cylinder of the physical micro-foaming device is connected to the nozzle. The nozzle is used to inject the melt in the melt cylinder into the mold to form a complete material forming channel.

[0023] The beneficial effects of this utility model are:

[0024] This invention provides a physically micro-foamed screw structure. In actual operation, the output end of the external drive mechanism is connected to the assembly section to drive the physically micro-foamed screw structure to rotate within the melt cylinder. After the material enters the plasticizing section and is heated to form a melt, it enters the first flow channel through the connecting hole on the outer periphery of the main body, converges at the check valve ball, and then flows into the mixing section through the second flow channel. Simultaneously, the external gas injection mechanism injects supercritical fluid into the mixing section through the gas injection hole on the melt cylinder to mix with the melt, completing the material processing. During this process, when the melt stops flowing, the check valve ball quickly adheres to the port of the first flow channel under back pressure, preventing melt backflow and improving the stability of the injection endpoint. The main body and connecting part of the check valve are detachable, reducing the overall structural complexity and processing difficulty, and decreasing processing costs. The plasticizing section, check valve section, and mixing section are all detachable independent parts, meaning that if a part is damaged, the entire screw does not need to be replaced, shortening the response time. Furthermore, it does not require excessively increasing the length of the melt cylinder, making it more adaptable.

[0025] This invention provides a physical micro-foaming device. The physical micro-foaming device adopts the above-mentioned physical micro-foaming screw structure. It provides a material processing space throughout the entire process through a melt cylinder. The air injection hole corresponds to the input end of the mixing section, which allows the air injection mechanism to accurately inject supercritical fluid. The drive mechanism stably drives the physical micro-foaming screw structure to rotate, ensuring that the melt and fluid are fully mixed, reducing melt backflow, and improving the operational stability of the physical micro-foaming device.

[0026] This invention provides an injection molding machine that allows the output end of the melt cylinder to directly connect to the nozzle, forming a complete material forming channel. This ensures stable injection of the melt into the mold. By relying on the check valve section of the physical micro-foaming screw structure in the physical micro-foaming device, melt backflow is reduced, injection stability is improved, processing and maintenance costs are reduced, and emergency response time is shortened. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the physical micro-foaming screw structure described in an embodiment of this utility model;

[0028] Figure 2 yes Figure 1 Sectional view at point AA;

[0029] Figure 3yes Figure 2 Enlarged view of point C in the middle;

[0030] Figure 4 This is a schematic diagram of the spherical check valve described in an embodiment of this utility model;

[0031] Figure 5 yes Figure 1 Enlarged view of point B in the middle;

[0032] Figure 6 yes Figure 5 Sectional view at point DD.

[0033] In the picture:

[0034] 1. Assembly section; 2. Plasticizing section; 21. Feeding section; 22. Compression section; 23. Metering section;

[0035] 3. Check valve section; 30. Ball check valve;

[0036] 301, Main body; 3010, Connecting hole; 3011, First flow channel;

[0037] 302. Connecting section; 3021. Second flow channel;

[0038] 303, Stop the backspin ball;

[0039] 4. Mixing section; 40. Spiral thread assembly;

[0040] 401, First threaded edge; 402, Second threaded edge; 4021, First groove;

[0041] 403, Third spiral ridge; 404, Fourth spiral ridge; 4041, Second groove. Detailed Implementation

[0042] The embodiments of this utility model are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar parts or parts having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0043] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0044] In the description of this utility model, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0045] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0046] In physical microfoaming injection molding technology, the physical microfoaming process is roughly as follows: supercritical fluid is injected into the melt under high pressure; when the melt enters the mold cavity, the pressure is rapidly reduced, causing the gas solubility to drop sharply, and the system instantly reaches a highly supersaturated state; under the effect of high supersaturation, gas molecules simultaneously, in large quantities, and uniformly form bubble nuclei throughout the melt; the bubble nuclei rapidly absorb the surrounding supersaturated gas and grow. Through precise temperature and pressure control, the bubbles that have grown to the micrometer size are rapidly frozen and solidified. The final product will contain a large number of extremely small, uniformly distributed closed bubble structures (usually at the micrometer level, typically ranging from 1 micrometer to 100 micrometers, with the average diameter limited to within 50 micrometers as much as possible).

[0047] It is worth noting that the supercritical fluids used in the physical micro-foaming process are mainly nitrogen and carbon dioxide. These two gases have stable chemical properties. In the supercritical state, they can maintain both the high diffusivity of gases and the high solubility of liquids. They can be dissolved in the melt efficiently and uniformly without reacting chemically with the melt, thus avoiding adverse effects on the material properties of the final micro-foamed product.

[0048] like Figures 1-4As shown, this embodiment provides a physically micro-foamed screw structure, a physically micro-foaming device, and an injection molding machine. The physically micro-foamed screw structure is disposed inside a melt cylinder, which has an injection port that can be connected to an external injection mechanism to inject supercritical fluid into the melt cylinder. The physically micro-foamed screw structure includes an assembly section 1, a plasticizing section 2, a check valve section 3, and a mixing section 4 connected sequentially along the material conveying direction. The assembly section 1 can be connected to the output end of an external drive mechanism to drive the entire physically micro-foamed screw structure to rotate. The material is heated in the plasticizing section 2 to form a melt. The check valve 3 is equipped with a spherical check valve 30, which includes a main body 301, a connecting part 302, and a check ball 303. The first end of the main body 301 and the first end of the connecting part 302 are detachably connected, and the second end of the main body 301 is detachably connected to the output end of the plasticizing section 2. The first end of the connecting part 302 is detachably connected to the first end of the connecting part 303. The two ends are detachably connected to the input end of the mixing section 4. The air injection hole is set corresponding to the input end of the mixing section 4 so that the supercritical fluid can mix with the melt in the mixing section 4. The check ball 303 is set in the receiving cavity formed by the main body 301 and the connecting part 302. The main body 301 has a connecting hole 3010 on its outer periphery. The main body 301 has a first flow channel 3011 communicating with the connecting hole 3010 inside. The connecting part 302 has a second flow channel 3021 communicating with the first flow channel 3011. The melt flowing out of the output end of the plasticizing section 2 flows through the connecting hole 3010 and the first flow channel 3011 to the check ball 303 in sequence, and flows to the mixing section 4 through the second flow channel 3021. The check ball 303 can fit with the port of the first flow channel 3011 to restrict the melt from flowing in the opposite direction of material conveying.

[0049] In this embodiment, the output end of the external drive mechanism is connected to the assembly section 1 to drive the physical micro-foaming screw structure to rotate inside the melt cylinder. After the material enters the plasticizing section 2 and is heated to form a melt, it enters the first flow channel 3011 through the connecting hole 3010 on the outer periphery of the main body 301, and gathers at the check ball 303. Then, it flows into the mixing section 4 through the second flow channel 3021. At the same time, the external gas injection mechanism injects supercritical fluid into the mixing section 4 through the gas injection hole on the melt cylinder to mix with the melt, thus completing the material processing. During this process, when the melt stops flowing, the check ball 303 quickly comes into contact with the port of the first flow channel 3011 under the action of back pressure, preventing melt backflow and improving the stability of the injection endpoint; the main body 301 and the connecting part 302 of the ball check valve 30 are detachably connected, reducing the overall structural complexity and processing difficulty, and reducing processing costs; the plasticizing section 2, the check section 3 and the mixing section 4 are all independent parts that can be disassembled, that is, when a part is damaged, there is no need to replace the entire screw, shortening the response time; at the same time, there is no need to excessively increase the length of the melt cylinder, making it more adaptable.

[0050] It is worth noting that when the melt from the plasticizing section 2 flows to the mixing section 4 and stops flowing, a pressure difference is formed between the mixing section 4 and the plasticizing section 2, causing the check ball 303 to fit against the port of the first flow channel 3011, precisely blocking the reverse flow of the melt, preventing the melt from flowing back to the plasticizing section 2 and causing conveying disorder, reducing material waste caused by backflow; ensuring stable melt pressure in the mixing section 4, laying the foundation for the orderly conveying of the melt to the mixing section 4 in the future, and further improving the stability of the injection endpoint.

[0051] It is worth noting that the physical micro-foaming screw structure achieves standardization and enhances interchangeability through the separate design of the plasticizing section 2, the check section 3, and the mixing section 4, facilitating modular production and replacement. Furthermore, it allows for flexible replacement of parts with different lengths and dimensional parameters to adapt to various application scenarios.

[0052] In this embodiment, the physical microfoaming device includes a melting cylinder, an injection mechanism, a drive mechanism, and a physical microfoaming screw structure. The physical microfoaming screw structure is disposed in the melting cylinder, which provides space for material conveying, melting, mixing, and foaming. The melting cylinder is provided with an injection port, which corresponds to the input end of the mixing section 4 of the physical microfoaming screw structure and can be connected to the injection mechanism for injecting supercritical fluid into the melting cylinder. The output end of the drive mechanism is connected to the assembly section 1 of the physical microfoaming screw structure to drive the physical microfoaming screw structure to rotate. This physical microfoaming device provides a full-process material handling space through the melting cylinder. The injection port, corresponding to the input end of the mixing section 4, allows the injection mechanism to accurately inject supercritical fluid. The drive mechanism stably drives the rotation of the physical microfoaming screw structure, ensuring thorough mixing of the melt and fluid, reducing melt backflow, and improving the operational stability of the physical microfoaming device.

[0053] In this embodiment, the injection molding machine includes a nozzle and a physical micro-foaming device. The output end of the melt cylinder of the physical micro-foaming device is connected to the nozzle. The nozzle is used to inject the melt in the melt cylinder into the mold to form a complete material forming channel. This injection molding machine allows the output end of the melt cylinder to directly connect to the nozzle, forming a complete material forming channel. This ensures stable melt injection into the mold. Relying on the check valve section 3 of the physical micro-foaming screw structure in the physical micro-foaming device, melt backflow is reduced, injection stability is improved, processing and maintenance costs are reduced, and emergency response time is shortened.

[0054] like Figure 3 As shown, the working outer diameter of the main body 301 is the same as that of the plasticizing section 2, and the working outer diameter of the connecting part 302 is the same as that of the mixing section 4. The transition between the check valve section 3 and the plasticizing section 2 and the mixing section 4 is smoother, allowing the outer wall of the physical micro-foaming screw structure to fit more evenly with the inner wall of the melt cylinder, avoiding gaps caused by differences in outer diameter that could lead to melt retention or leakage, and ensuring smooth melt delivery.

[0055] It is worth noting that the working outer diameter of the main body 301 is consistent with that of the plasticizing section 2 and is subject to tolerance requirements, and the working outer diameter of the connecting part 302 is consistent with that of the mixing section 4 and is subject to tolerance requirements. This can minimize the gap between the outer wall of the screw and the inner wall of the melt cylinder, completely avoid the melt from being stuck or leaking due to the gap, ensure smoother conveying, ensure that the supercritical fluid is mixed more evenly with the melt in the mixing section 4, and improve the final molding quality.

[0056] like Figure 3 As shown, the first end of the main body 301 is provided with a first external thread, and the first end of the connecting part 302 is provided with a first internal thread that mates with the first external thread, so that the first end of the main body 301 and the first end of the connecting part 302 are detachably threadedly connected. The first external thread at the first end of the main body 301 mates with the first internal thread at the first end of the connecting part 302, realizing a detachable threaded connection between the two. This makes disassembly and assembly convenient and the connection stable. In the event of maintenance of the check ball 303 or damage to a local component, it can be replaced separately without disassembling the entire physical micro-foamed screw structure, which greatly shortens the maintenance time. At the same time, the threaded connection has good sealing performance, which can reduce the risk of melt leakage at the connection of the check section 3, ensure the stability of melt delivery, and reduce the overall maintenance cost of the screw.

[0057] In this embodiment, the main body 301 is provided with a first positioning port, and the connecting part 302 is provided with a second positioning port. The first and second positioning ports can be matched by shape adaptation to form a positioning fit. When the main body 301 and the connecting part 302 are threadedly connected, the relative positions of the main body 301 and the connecting part 302 in the circumferential and axial directions are defined. On the one hand, during manual operation, the first positioning port of the main body 301 and the second positioning port of the connecting part 302 can be accurately positioned during the threaded connection process through shape adaptation, effectively preventing damage or connection failure caused by excessive rotation of the threads. On the other hand, ensuring that the threads are screwed into the preset position ensures the accurate circumferential and axial relative positions of the main body 301 and the connecting part 302, thereby allowing the first flow channel 3011 and the second flow channel 3021 to be stably aligned, providing a reliable guarantee for smooth melt delivery.

[0058] like Figures 3-4As shown, the second end of the main body 301 is provided with a second external thread, and the output end of the plasticizing section 2 is provided with a second internal thread that mates with the second external thread, so that the second end of the main body 301 and the output end of the plasticizing section 2 are detachably threadedly connected; the second end of the connecting part 302 is provided with a third external thread, and the input end of the mixing section 4 is provided with a third internal thread that mates with the third external thread, so that the second end of the connecting part 302 and the input end of the mixing section 4 are detachably threadedly connected. The second external thread at the second end of the main body 301 mates with the second internal thread at the output end of the plasticizing section 2, and the third external thread at the second end of the connecting part 302 mates with the third internal thread at the input end of the mixing section 4, realizing a detachable connection. This connection is convenient and stable, and there is no need to replace the entire physical micro-foamed screw structure when a partial component is damaged, reducing maintenance costs and time. It also ensures the sealing of the connection between the check valve section 3 and the plasticizing section 2 and the mixing section 4, reducing melt leakage and improving conveying stability.

[0059] like Figures 5-6 As shown, multiple helical rib groups 40 are spaced apart along the axial direction on the mixing section 4. Each helical rib group 40 includes a first helical rib 401, a second helical rib 402, a third helical rib 403, and a fourth helical rib 404 arranged sequentially along its axial direction. The first helical rib 401 and the third helical rib 403 are grooveless structures. The second helical rib 402 has multiple first grooves 4021 circumferentially, and the fourth helical rib 404 has multiple second grooves 4041 circumferentially. The first grooves 4021 and the second grooves 4041 are staggered. On the one hand, the multiple helical rib groups 40 spaced apart along the axial direction in the mixing section 4, with the first helical rib 401 and the third helical rib 403 in each group being grooveless and able to stably transport the melt, and the staggered distribution of the first grooves 4021 of the second helical rib 402 and the second grooves 4041 of the fourth helical rib 404, can significantly increase the contact area between the melt and the supercritical fluid, enhance the shear mixing effect between the two, and make the mixing more uniform. On the other hand, the combination of multiple sets of screw threads 40 can prevent material stagnation, ensure smooth conveying, and further improve the quality and stability of the final foamed product.

[0060] In this embodiment, two helical rib groups 40 are spaced apart along the axial direction of the mixing section 4 to enhance the mixing effect and homogenization, avoid uneven bubble structure, and ensure smooth melt transport. At the same time, reducing the number of groups also lowers the processing difficulty and cost of the mixing section 4, balancing mixing effect and production practicality, and providing support for the stability of product quality in subsequent foaming molding. In other embodiments, the number of helical rib groups 40 spaced apart along the axial direction of the mixing section 4 can also be three, four, etc., and is not specifically limited here.

[0061] It is worth noting that in conventional designs, the thread width of the screw ribs is typically 3% to 8% of the screw's outer diameter. This narrower thread width makes the screw ribs more susceptible to wear and deformation due to concentrated stress. In this embodiment, the individual screw ribs of the screw rib group 40, while adapting to the overall screw structure, have a larger volume than conventional screw ribs through optimized dimensional design. This effectively disperses stress, improves stress uniformity, and significantly enhances the wear and deformation resistance of the individual screw ribs, extending the service life of the physically micro-foamed screw structure.

[0062] like Figures 1-2 As shown, the plasticizing section 2 includes a feeding section 21, a compression section 22, and a metering section 23 connected sequentially along the material conveying direction. The feeding section 21 is used to convey solid material particles; the compression section 22 is used to compact and melt the material; and the metering section 23 is used to homogenize the melt temperature and viscosity, enhance the shearing effect on the melt, and provide a stable pressure environment for subsequent supercritical fluid injection. The output end of the metering section 23 is detachably connected to the second end of the main body 301. On the one hand, the feeding section 21, compression section 22, and metering section 23 of the plasticizing section 2 are connected in an orderly manner along the material conveying direction, realizing a smooth transformation of the material from a solid state to a uniform molten state, providing a high-quality melt foundation for subsequent mixing and foaming; on the other hand, the detachable connection between the output end of the metering section 23 and the second end of the main body 301 facilitates local inspection and maintenance.

[0063] like Figures 1-2 As shown, the bottom diameter of the feeding section 21 is fixed, and the thread depth of the feeding section 21 is fixed and the largest in the plasticizing section 2. The bottom diameter of the compression section 22 gradually increases along the material conveying direction, so that the thread depth of the compression section 22 gradually decreases along the material conveying direction. The bottom diameter of the metering section 23 is fixed, and the thread depth of the metering section 23 is fixed and smaller than the thread depths of the feeding section 21 and the compression section 22, and is the smallest in the plasticizing section 2. The fixed bottom diameter and thread depth of the feeding section 21, which is the largest in the plasticizing section 2, can accommodate more solid material particles and ensure smooth feeding. The gradually increasing bottom diameter and decreasing thread depth of the compression section 22 can gradually compact the material and improve melting efficiency. The fixed bottom diameter and thread depth of the metering section 23, which is the smallest, can enhance the melt shearing and homogenization effect and stabilize the melt pressure. The coordinated dimensions of the three sections achieve efficient material conversion, laying a good foundation for subsequent supercritical fluid injection and mixing foaming.

[0064] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A physical micro-foaming screw structure, disposed inside a melt cylinder, wherein the melt cylinder is provided with an injection port, the injection port being connectable to an external injection mechanism for injecting supercritical fluid into the melt cylinder, characterized in that, The physical micro-foaming screw structure includes an assembly section (1), a plasticizing section (2), a check section (3), and a mixing section (4) connected sequentially along the material conveying direction. The assembly section (1) can be connected to the output end of an external drive mechanism to drive the physical micro-foaming screw structure to rotate as a whole. The material is heated through the plasticizing section (2) to form a melt. The check valve section (3) is equipped with a ball check valve (30), which includes a main body (301), a connecting part (302), and a check ball (303). The first end of the main body (301) and the first end of the connecting part (302) are detachably connected. The second end of the main body (301) is detachably connected to the output end of the plasticizing section (2). The second end of the connecting part (302) is detachably connected to the input end of the mixing section (4). The air injection port is connected to the input end of the mixing section (4). The supercritical fluid is configured to mix with the melt in the mixing section (4); the check ball (303) is disposed in the cavity formed by the main body (301) and the connecting part (302); the main body (301) is provided with a connecting hole (3010) on its outer periphery; the main body (301) is provided with a first flow channel (3011) communicating with the connecting hole (3010) inside; and the connecting part (302) is provided with a second flow channel (3021) communicating with the first flow channel (3011). The melt flowing out of the output end of the plasticizing section (2) flows sequentially through the connecting hole (3010) and the first flow channel (3011) to the check ball (303), and then flows through the second flow channel (3021) to the mixing section (4). The check ball (303) can fit with the port of the first flow channel (3011) to restrict the melt from flowing in the opposite direction of the material conveying.

2. The physically micro-foamed screw structure according to claim 1, characterized in that, The working outer diameter of the main body (301) is the same as the working outer diameter of the plasticizing section (2), and the working outer diameter of the connecting part (302) is the same as the working outer diameter of the mixing section (4).

3. The physically micro-foamed screw structure according to claim 1, characterized in that, The first end of the main body (301) is provided with a first external thread, and the first end of the connecting part (302) is provided with a first internal thread that mates with the first external thread, so that the first end of the main body (301) and the first end of the connecting part (302) can be detachably threadedly connected.

4. The physically micro-foamed screw structure according to claim 3, characterized in that, The main body (301) is provided with a first positioning port, and the connecting part (302) is provided with a second positioning port. The first positioning port and the second positioning port can be connected by shape adaptation to form a positioning fit. When the main body (301) and the connecting part (302) are threadedly connected, the relative positions of the main body (301) and the connecting part (302) in the circumferential and axial directions are defined.

5. The physically micro-foamed screw structure according to claim 1, characterized in that, The second end of the main body (301) is provided with a second external thread, and the output end of the plasticizing section (2) is provided with a second internal thread that mates with the second external thread, so that the second end of the main body (301) and the output end of the plasticizing section (2) are detachably threadedly connected; the second end of the connecting part (302) is provided with a third external thread, and the input end of the mixing section (4) is provided with a third internal thread that mates with the third external thread, so that the second end of the connecting part (302) and the input end of the mixing section (4) are detachably threadedly connected.

6. The physically micro-foamed screw structure according to any one of claims 1-5, characterized in that, The mixing section (4) is provided with a plurality of spiral rib groups (40) spaced apart along its axial direction. Each spiral rib group (40) includes a first spiral rib (401), a second spiral rib (402), a third spiral rib (403) and a fourth spiral rib (404) arranged sequentially along its axial direction. The first spiral rib (401) and the third spiral rib (403) are both grooveless structures. The second spiral rib (402) is provided with a plurality of first grooves (4021) in the circumferential direction. The fourth spiral rib (404) is provided with a plurality of second grooves (4041) in the circumferential direction. The first grooves (4021) and the second grooves (4041) are staggered.

7. The physically micro-foamed screw structure according to any one of claims 1-5, characterized in that, The plasticizing section (2) includes a feeding section (21), a compression section (22) and a metering section (23) connected sequentially along the material conveying direction. The feeding section (21) is used to convey solid material particles; the compression section (22) is used to compact and melt the material; the metering section (23) is used to homogenize the temperature and viscosity of the melt, enhance the shearing effect on the melt, and provide a stable pressure environment for the subsequent supercritical fluid injection. The output end of the metering section (23) is detachably connected to the second end of the main body (301).

8. The physically micro-foamed screw structure according to claim 7, characterized in that, The bottom diameter of the feeding section (21) is fixed, and the thread depth of the feeding section (21) is fixed and is the largest among the plasticizing sections (2); the bottom diameter of the compression section (22) gradually increases along the material conveying direction so that the thread depth of the compression section (22) gradually decreases along the material conveying direction; the bottom diameter of the metering section (23) is fixed, and the thread depth of the metering section (23) is fixed and is smaller than the thread depth of the feeding section (21) and the compression section (22), and is the smallest among the plasticizing sections (2).

9. A physical micro-bubbling device, characterized in that, The device includes a melt cylinder, an injection mechanism, a drive mechanism, and a physical micro-foaming screw structure as described in any one of claims 1-8. The physical micro-foaming screw structure is disposed in the melt cylinder, which provides space for material conveying, melting, mixing, and foaming. The melt cylinder is provided with an injection hole, which is correspondingly disposed to the input end of the mixing section (4) of the physical micro-foaming screw structure and can be connected to the injection mechanism for injecting supercritical fluid into the melt cylinder. The output end of the drive mechanism is connected to the assembly section (1) of the physical micro-foaming screw structure to drive the physical micro-foaming screw structure to rotate.

10. An injection molding machine, characterized in that, The device includes a nozzle and the physical micro-foaming device as described in claim 9, wherein the output end of the melt cylinder of the physical micro-foaming device is connected to the nozzle, and the nozzle is used to inject the melt in the melt cylinder into the mold to form a complete material forming channel.

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