Nozzle for foaming co-injection

Abstract

Relates to the technical field of polymer co-injection processing, in particular to a nozzle for foaming co-injection. The nozzle comprises a nozzle body, a valve element coaxially arranged and installed in the nozzle body in a sliding mode, a charging barrel connecting sleeve fixedly connected to the nozzle body and used for introducing melt, and a nozzle head arranged at the end, away from the charging barrel connecting sleeve, of the valve element and used for stretching into a mold sprue. The charging barrel connecting sleeve is provided with a feeding port for melt to enter, the nozzle head is provided with a discharging port for injecting the melt, and the valve element is provided with a center runner used for communicating the feeding port with the discharging port at the axis position. The co-injection molding device has the effects that a stable skin-core-skin structure of a workpiece can be ensured, and the co-injection molding quality is improved.

Description

Technical Field

[0001] The present application relates to the technical field of polymer co-injection processing, and in particular to a nozzle for foaming co-injection. Background Art

[0002] The existing polymer co-injection nozzle is a nozzle specially designed for the co-injection molding process, which can inject two or more different polymer melts into the gate of the mold simultaneously or sequentially. In order to ensure that the melt in the nozzle does not pre-foam due to pressure loss during the injection process, the nozzle has the function of opening during injection and closing after the injection. The structure of this nozzle is quite complicated and cannot ensure the layered injection of different melts.

[0003] In the related art, the problem of flow channel distribution may cause the core layer and the skin layer to penetrate each other in the nozzle, thus failing to maintain the required skin-core-skin structure. In order to meet the skin-core-skin ratio required for the product, it is sometimes necessary to increase the storage ratio of the skin layer material and reduce the amount of the core layer material. According to the material flow sequence of skin-core-skin, it is often difficult to ensure that the skin layer material can completely remove the core layer material during the material flow conversion process from skin to core and then to skin, resulting in the residual core layer material being mixed in the skin layer, destroying the skin layer of the co-injected part, and resulting in the production of defective products.

[0004] In view of the above problems, the existing co-injection nozzles require a large amount of skin material to completely remove the core material. Therefore, this type of nozzle is not suitable for forming co-injection parts with a long flow length ratio and a large ratio of core layer to skin layer. In order to solve these problems, it is necessary to improve the structure of the co-injection nozzle to ensure that the parts can maintain a stable skin-core-skin structure and improve the quality of co-injection molding. Summary of the invention

[0005] In order to ensure that the product can maintain a stable skin-core-skin structure and improve the quality of co-injection molding, the present application provides a nozzle for foaming co-injection.

[0006] The present application provides a nozzle for foaming co-injection using the following technical solution: A nozzle for foaming co-injection, comprising a nozzle body, a valve core coaxially arranged and slidably mounted inside the nozzle body, a barrel coupling sleeve fixedly connected to the nozzle body and used for passing melt, and a nozzle head sleeved on one end of the valve core away from the barrel coupling sleeve and used for extending into a mold gate; The barrel connecting sleeve has a feed port for the melt to enter, the nozzle head has a discharge port for extruding the melt, and the valve core has a central flow channel at the axial position for connecting the feed port and the discharge port.

[0007] By adopting the above technical solution, the valve core and the nozzle body are coaxially slidably installed, and the central flow channel set in the valve core is connected to the discharge port at the front end and the feed port at the rear end to ensure the smooth passage of the melt. By adjusting the sliding and switching timing of the valve core, the nozzle can be adapted to different injection molding requirements, including different skin and core layer ratios, and different melt characteristics. At the same time, it also ensures that the different melts of the skin layer material and the core layer material can be layered and injected sequentially during the injection process, reducing the residue of the core layer material in the skin layer, thereby maintaining the skin-core-skin structure required for the part. The structure of the nozzle is relatively complex, but it simplifies the operation process. Through the automated valve core sliding switch function, the need for manual intervention is reduced, and production efficiency is improved.

[0008] Furthermore, the valve core comprises a first valve section, a second valve section, and a third valve section which are coaxially arranged and fixedly connected in sequence; The first valve section has a nozzle outlet for communicating with the discharge port; The third valve section has a core layer central feed channel for communicating with the feed port, and one end of the third valve section close to the barrel connecting sleeve is provided with a limiting flange block on the outer peripheral wall for abutting against the end of the nozzle body; The second valve section has a core layer orifice for connecting the core layer central feed channel and the nozzle outlet.

[0009] By adopting the above technical solution, the valve core is divided into the first valve section, the second valve section and the third valve section. The segmented design makes the flow path of the skin layer material and the core layer material in the nozzle more clear and controllable. The nozzle outlet of the first valve section is directly connected to the discharge port to ensure the smooth extrusion of the melt; the core layer center feed channel of the third valve section is connected to the feed port to provide a channel for the injection of the core layer material. The limit flange block set at one end of the third valve section close to the barrel connecting sleeve plays a role in stabilizing the position of the valve core. During the operation of the nozzle, the limit flange block is tightly abutted against the end of the nozzle body to prevent the valve core from shifting or shaking under the action of the high-pressure melt. The core layer small hole on the second valve section is the key channel connecting the core layer center feed channel and the nozzle outlet. It also provides a separate channel for the entry of the skin layer material, which can further control the wrapping effect of the skin layer material on the core layer material, ensuring that the core layer material is completely wrapped by the skin layer material during the extrusion process, forming a stable skin-core-skin structure. The small holes in the core layer help to adjust the flow rate and pressure of the melt, thereby optimizing the quality of co-injection molding, achieving precise stratification of the skin and core layers, and avoiding mutual penetration of the melt in the nozzle.

[0010] Furthermore, the valve core is provided with a cortex inlet groove along the length direction on the outer wall, and the first valve section is provided with a cortex radial feed hole radially on the side wall, and the cortex radial feed hole is interconnected with the cortex inlet groove and the nozzle outlet.

[0011] By adopting the above technical solution, when the nozzle body slides to the point where the cortex inlet groove is connected to the feed port of the barrel connecting sleeve, it is equivalent to opening the feed channel of the cortex melt separately, and the cortex melt enters the cortex inlet groove from the feed port, and then enters the nozzle outlet from the cortex radial feed hole. The cooperation of the cortex inlet groove and the cortex radial feed hole enables the cortex material to flow along a specific path and be accurately introduced into the nozzle outlet, thereby enhancing the nozzle's control over the cortex material, helping to form a more uniform and stable cortex structure, and optimizing the wrapping effect of the cortex on the core layer, thereby obtaining a higher quality skin-core-skin structure.

[0012] Furthermore, the inner diameter of the core layer hole is smaller than the inner diameter of the core layer central feed channel and the nozzle outlet, the second valve section is radially provided with a core layer switch pin for controlling the opening and closing of the core layer hole at the center position, the second valve section is provided with an opening and closing slide groove for the core layer switch pin to be installed and slided, the nozzle body is provided with a guide ball socket groove on the inner wall which matches the end of the core layer switch pin, and the second valve section is radially provided with a throttling hole for communicating with the core layer hole on the opposite side of the opening and closing slide groove.

[0013] By adopting the above technical solution, the setting of the core layer switch pin achieves the effect of accurately controlling the opening and closing of the core layer small hole. When the nozzle body slides to the guide ball socket groove where the core layer switch pin is aligned with the inner wall of the nozzle body, the skin layer material enters the throttle hole from the skin layer inlet groove and forms fluid pressure, forcing the core layer switch pin to overcome the friction force and enter the guide ball socket groove from the opening and closing slide groove, so that the skin layer small mouth is opened and connects the core layer center feed channel and the nozzle outlet, the core material melt enters the core layer center feed channel from the feed inlet, and then enters the nozzle outlet through the core layer small hole, at this time, the skin layer melt flow channel and the core layer melt flow channel are opened at the same time, so as to obtain a stable skin-core-skin structure.

[0014] Furthermore, the outer wall of the nozzle head is provided with a front end convex step, the outer wall of the nozzle body is provided with a rear end convex step, the nozzle head and the nozzle body are externally sleeved with a pressure spring, and the pressure spring abuts between the front end convex step and the rear end convex step.

[0015] By adopting the above technical solution, when the nozzle head is inserted into the mold gate, the pressure causes the valve core to slide in the nozzle body, thereby opening the skin layer flow channel and the core layer flow channel in turn, and the pressure spring provides rebound force for the nozzle head and the valve core. During the injection process, when the melt is extruded through the nozzle head, the pressure spring can use its own elastic force to automatically reset the nozzle head and the valve core to the initial position. The automatic reset function ensures the stability and reliability of the nozzle during continuous injection, reducing errors and downtime caused by manual reset.

[0016] Furthermore, the number of the cortex inlet grooves and the cortex radial feed holes are both multiple and arranged in one-to-one correspondence, each of the cortex inlet grooves is circumferentially arranged on the outer wall of the valve core, and each of the cortex radial feed holes is circumferentially arranged on the first valve section.

[0017] By adopting the above technical solution, the provision of multiple skin layer inlet grooves and skin layer radial feed holes allows the skin layer material to be evenly distributed in the valve core and the nozzle, which helps to form a more uniform and stable skin layer structure during the injection process and improve the quality of the product. Due to the increase in the number of skin layer inlet grooves and skin layer radial feed holes, the skin layer material can more fully wrap the core layer material. This enhanced wrapping effect helps to reduce the exposure and leakage of the core layer material, thereby obtaining a more complete skin-core-skin structure.

[0018] Furthermore, the limiting flange block is provided with an inclined abutting surface at a side close to the nozzle body, and the end of the nozzle body is provided with an abutting sealing surface matched with the inclined abutting surface.

[0019] By adopting the above technical solution, the cooperation of the inclined abutting surface and the abutting sealing surface improves the reliability of the valve core closing. When the valve core moves forward to the inside of the nozzle body under the action of the spring force and slides to a predetermined position, the inclined abutting surface and the abutting sealing surface are in close contact with each other, ensuring that the valve core can be accurately positioned at the required position and close the skin layer inlet, ensuring the sealing of the nozzle closure.

[0020] Furthermore, the diameter of the nozzle head gradually decreases at an end away from the nozzle body.

[0021] By adopting the above technical solution, the gradual reduction of the nozzle tip diameter helps to optimize the flow of the melt and reduce the residual melt inside the nozzle tip. During the injection molding process, when the melt is ejected from the nozzle tip, due to the smaller diameter at the end of the nozzle tip, the melt will be subjected to a higher shear rate and higher injection pressure, making its flow smoother and more stable, which helps to improve the filling efficiency of the melt and the quality of the product. After the injection molding is completed, due to the smaller diameter at the end of the nozzle tip, the melt is easier to be completely extruded, thereby reducing the retention and solidification of the melt inside the nozzle tip.

[0022] In summary, the present application includes at least one of the following beneficial technical effects: Through the segmented design of the valve core and the coordination of the core layer small hole, the skin layer inlet groove and the skin layer radial feed hole, the skin layer material and the core layer material are accurately layered and injected sequentially in the nozzle. The core layer small hole, the skin layer inlet groove and the skin layer radial feed hole optimize the flow path of the melt, so that the skin layer material can be evenly distributed in the nozzle to form a stable skin layer structure, ensuring that the core layer material is completely wrapped by the skin layer material. The core layer switch pin accurately controls the entry of the core material, further enhancing the wrapping effect of the skin layer on the core layer, avoiding mutual penetration of the melt in the nozzle, thereby obtaining a high-quality skin-core-skin structure; The pressure spring between the nozzle head and the nozzle body provides rebound force for the nozzle head and the valve core, realizing the automatic reset function of the valve core, reducing the need for manual intervention and improving production efficiency; The cooperation of the inclined abutment surface and the abutment guide surface makes the sliding process of the valve core in the nozzle body smoother and more stable, ensuring that the valve core can be accurately positioned at a desired position, thereby improving the stability and accuracy of injection molding. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of a nozzle used for foaming co-injection in an embodiment of the present application.

[0024] Figure 2 It is a schematic diagram of the structural decomposition of a nozzle used for foaming co-injection in an embodiment of the present application.

[0025] Figure 3 It is a schematic diagram of the cross-sectional structure of the nozzle in the embodiment of the present application in a completely closed state.

[0026] Figure 4 It is a schematic diagram of the cross-sectional structure of the nozzle in the embodiment of the present application when only the cortical flow channel is open.

[0027] Figure 5 It is a schematic diagram of the cross-sectional structure of the nozzle in the embodiment of the present application when the skin layer flow channel and the core layer flow channel are simultaneously opened.

[0028] Explanation of the reference numerals: 1. nozzle body; 11. rear end convex step; 12. abutting sealing surface; 13. guiding ball socket groove; 2. nozzle head; 21. front end convex step; 22. discharge port; 3. barrel connecting sleeve; 31. feed port; 4. valve core; 41. first valve section; 411. nozzle outlet channel; 412. radial feed hole of the cortex layer; 42. second valve section; 421. small hole of the core layer; 422. switch pin of the core layer; 4221. opening and closing slide groove; 423. throttle hole; 43. third valve section; 431. limiting flange; 4311. inclined abutting sealing surface; 432. central feed channel of the core layer; 44. cortex inlet groove; 5. pressure spring. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of this application more clear, the following Figure 1-5 And embodiments, the present application is further described in detail.

[0030] The present application embodiment discloses a nozzle for foaming co-injection. Figure 1 and Figure 2 The spring nozzle for foaming co-injection includes a nozzle body 1, a nozzle head 2, a barrel connecting sleeve 3, a valve core 4 and a pressure spring 5.

[0031] The valve core 4 is coaxially penetrated and slidably installed inside the nozzle body 1, the barrel connecting sleeve is fixedly connected to one end of the nozzle body 1 and is used to pass the melt, the nozzle head 2 is sleeved and fixedly connected to the end of the valve core 4 away from the barrel connecting sleeve 3, and the diameter of the nozzle head 2 away from the nozzle body 1 gradually decreases to match the mold gate diameter.

[0032] The outer peripheral wall of the nozzle head 2 is integrally connected with a front convex step 21, and the outer peripheral wall of the nozzle body 1 is integrally connected with a rear convex step 11. The pressure spring 5 is sleeved on the outside of the nozzle head 2 and the nozzle body 1, and the two ends of the pressure spring 5 are respectively abutted between the two opposite side surfaces of the front convex step 21 and the rear convex step 11. When the nozzle head 2 is extended into and closely contacts the mold gate sleeve by the mold shifting drive, the mold shifting force overcomes the elastic force of the spring 5 to make the valve core 4 slide in the nozzle body 1, and the pressure spring 5 can provide a rebound force for the nozzle head 2 and the valve core 4 to reset.

[0033] Combination Figure 3 The barrel connecting sleeve 3 has a feed port 31 for the melt to enter at the axial position, the nozzle head 2 has a discharge port 22 for injecting the melt at the axial position, and the valve core 4 has a central and peripheral flow channel for connecting the feed port 31 and the discharge port 22 at the axial position, thereby ensuring smooth passage of the melt.

[0034] In this embodiment, the valve core 4 includes a first valve section 41, a second valve section 42 and a third valve section 43 which are coaxially arranged and connected in sequence. The third valve section 43 is located on the side close to the barrel connecting sleeve 3, and one end of the third valve section 43 close to the barrel connecting sleeve is integrally connected to the outer peripheral wall with a limiting flange 431 for abutting against the end of the nozzle body 1. The limiting flange 431 is provided with an inclined abutting sealing surface 4311 on the side close to the nozzle body 1, and the end of the nozzle body 1 is provided with an abutting sealing surface 12 matched with the inclined abutting surface 4311. When the valve core 4 moves toward the inside of the nozzle body 1 under pressure and slides to a predetermined position, the inclined abutting sealing surface 4311 abuts against the abutting sealing surface 12 to ensure that the valve core 4 can be accurately positioned at the required sealing position and ensure the sealing of the nozzle closure.

[0035] The first valve section 41 has a nozzle outlet channel 411 at the axial position for communicating with the discharge port 22, the third valve section 43 has a core layer central feed channel 432 at the axial position for communicating with the feed port 31, and the second valve section 42 has a core layer small hole 421 for connecting the core layer central feed channel 432 and the nozzle outlet 411, and the diameter of the core layer small hole 421 is smaller than the diameter of the core layer central feed channel 432 and the nozzle outlet channel 411. The nozzle outlet channel 411, the core layer small hole 421 and the core layer central feed channel 432 together constitute a complete central flow channel.

[0036] The valve core 4 is provided with a plurality of skin layer inlet grooves 44 along the length direction on the outer wall, and the first valve section 41 is provided with a skin layer radial feed hole 412 in the radial direction of the side wall, and the skin layer radial feed hole 412 is located at a position of the first valve section 41 close to the second valve section 42, and the skin layer radial feed hole 412 is interconnected with the skin layer inlet groove 44 and the nozzle outlet channel 411. The second valve section 42 is provided with a core layer switch pin 422 in the radial direction at the center position, and the second valve section 42 is provided with an opening and closing slide groove 4221 for the core layer switch pin 422 to be installed and slided, and the nozzle body 1 is provided with a guide ball socket groove 13 on the inner wall for the end of the core layer switch pin 422 to be inserted. The core layer switch pin 422 can be used to control the opening and closing of the core layer hole 421. When the nozzle does not inject melt into the mold gate and the core layer is closed, the core layer switch pin 422 leaves the ball socket groove 13 and is completely confined in the opening and closing slide groove 4221. The core layer hole 421 is blocked by the core layer switch pin 422 to prevent the core layer melt from passing through.

[0037] Reference Figure 3 and Figure 4 When the nozzle body 1 slides to the point where the cortex inlet groove 44 is connected to the feed port 31 of the barrel connecting sleeve 3 and the core layer switch pin 422 is not in the ball groove 13, it is equivalent to opening the feed channel of the cortex melt alone. The cortex melt enters the cortex inlet groove 44 from the feed port 31 and then enters the nozzle outlet 411 from the cortex radial feed hole 412. At this time, the parts extruded from the nozzle outlet 411 are all composed of cortex material.

[0038] Reference Figure 3 and Figure 5 , the second valve section 42 is radially provided with a throttle hole 423 for communicating with the core layer small hole 421 on the opposite side of the opening and closing slide groove 4221. When the nozzle body 1 slides to the guide ball socket groove 13 on the inner wall of the nozzle body 1 where the core layer switch pin 422 is aligned, the skin layer material enters the throttle hole 423 from the skin layer inlet groove 44 and forms fluid pressure, forcing the core layer switch pin 422 to overcome the friction force and enter the guide groove 13 from the opening and closing slide groove 4221, so that the skin layer small mouth is opened and connects the core layer center feed channel 432 and the nozzle outlet 411, and the core material melt enters the core layer center feed channel 432 from the feed port 31, and then enters the nozzle outlet 411 through the core layer small hole 421. At this time, the skin layer melt flow channel and the core layer melt flow channel are opened at the same time, and the melt injected from the nozzle outlet channel 411 is a stable skin-in-core structure. When extrusion needs to be stopped, the nozzle body 1 gradually moves away from the mold gate, and the nozzle returns to Figure 4 state, at this time, the melt injected from the nozzle outlet channel 411 is composed of skin material.

[0039] The implementation principle of a nozzle for foaming co-injection in the embodiment of the present application is as follows: the skin layer flow channel and the core layer flow channel are separated at the feed port 31 of the barrel connecting sleeve. The skin layer material enters the nozzle outlet 411 from the skin layer inlet groove 44 on the periphery of the valve core 4, that is, the skin layer channel is opened first, and the core layer channel is still closed. When the skin layer channel is fully opened and begins to flow into the nozzle outlet 411 to establish the melt pressure, this pressure acts on the bottom of the switch pin through the throttle hole 423, forcing the core layer switch pin 422 to overcome the friction of the pin displacement and reach the open position, thereby opening the core layer flow channel. In the subsequent nozzle flow field, the skin layer channel continues to be opened at the same time, and the skin layer material enters from the periphery of the nozzle outlet channel 411, that is, the outer layer material of the nozzle outlet 411 flow field is formed, while the core layer material needs to enter the nozzle outlet 411 through the middle core layer small hole 421 which is much smaller than the aperture of the nozzle outlet channel 411, so that it can only be wrapped by the outer layer skin to form a sandwich structure, and then enter the mold gate together with this flow field. This ensures to the greatest extent possible that the core layer material will not penetrate the skin layer prematurely and destroy the co-injected skin-core-skin structure.

[0040] The pressure drop gradient between the core layer central feed channel 432 and the core layer small hole 421 maximizes the pressure drop gradient of the core layer through the small hole 421, thereby increasing the nucleation rate of the pores, increasing the number of pore nucleation points to form a micro-bubble structure of the core layer, and finally obtaining a relatively smooth skin-wrapped micro-bubble core layer sandwich micro-bubble product, which is another feature and advantage of the present application. This eliminates the surface finish defects of the micro-bubble part.

[0041] When the nozzle is closed, the core layer switch pin 422 reaches the closed position first, while the skin layer inlet is still partially open. This ensures that the nozzle outlet channel 411 will not have more core layers than skin layers when the nozzle is closed. In this way, when the next cycle starts at the same time, it is still guaranteed that the skin layer is the main layer and wraps the core layer material that may remain in the center layer. The opening and closing of the nozzle is completely achieved by the mechanical movement of the valve core 4 and the core layer switch pin 422 by the forward and backward movement of the nozzle head 2. The opening of the core layer switch pin 422 is completed by the combined action of mechanical movement and skin layer melt pressure, which can ensure timely opening. The closing of the core layer switch pin 422 is completely forced by mechanical movement, mainly by the spring reset that forces the nozzle valve core 4 to move and drives the core layer switch pin 422 back to the closed position.

[0042] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A nozzle for foaming co-injection, characterized in that: It comprises a nozzle body (1), a valve core (4) coaxially arranged and slidably mounted inside the nozzle body (1), a barrel connecting sleeve (3) fixedly connected to the nozzle body (1) and used for passing melt, and a nozzle head (2) arranged at one end of the valve core (4) away from the barrel connecting sleeve (3) and used for extending into a mold gate; The barrel connecting sleeve has a feed port (31) for the melt to enter, the nozzle head (2) has a discharge port (22) for injecting the melt, and the valve core (4) has a central flow channel at the axial position for connecting the feed port (31) and the discharge port (22).

2. A nozzle for foaming co-injection according to claim 1, characterized in that: The valve core (4) comprises a first valve section (41), a second valve section (42), and a third valve section (43) which are coaxially arranged and fixedly connected in sequence; The first valve section (41) has a nozzle outlet (411) for communicating with the discharge port (22); The third valve section (43) has a core layer central feed channel (432) for communicating with the feed port (31); and one end of the third valve section (43) close to the barrel connecting sleeve is provided with a limiting flange (431) on the outer peripheral wall for abutting and sealing against the end of the nozzle body (1); The second valve section (42) has a core layer small hole (421) for connecting the core layer central feed channel (432) and the nozzle outlet (411).

3. A nozzle for foaming co-injection according to claim 2, characterized in that: The valve core (4) is provided with a cortex inlet groove (44) along the length direction on the outer wall, and the first valve section (41) is provided with a cortex radial feed hole (412) in the radial direction of the side wall, and the cortex radial feed hole (412) is interconnected with the cortex inlet groove (44) and the nozzle outlet (411).

4. A nozzle for foaming co-injection according to claim 3, characterized in that: The inner diameter of the core layer hole (421) is smaller than the inner diameters of the core layer central feed channel (432) and the nozzle outlet (411); the second valve section (42) is radially provided with a core layer switch pin (422) at the center position for controlling the opening and closing of the core layer hole (421); the second valve section (42) is provided with an opening and closing slide groove (4221) for the core layer switch pin (422) to be installed and slid; the nozzle body (1) is provided with a guide groove (13) on the inner wall thereof for matching with the end of the core layer switch pin (422); the second valve section (42) is radially provided with a throttling hole (423) for communicating with the core layer hole (421) on the opposite side of the opening and closing slide groove (4221).

5. A nozzle for foaming co-injection according to claim 4, characterized in that: The outer wall of the nozzle head (2) is provided with a front end convex step (21), and the outer wall of the nozzle body (1) is provided with a rear end convex step (11). The nozzle head (2) and the nozzle body (1) are externally sleeved with a pressure spring (5), and the pressure spring (5) is abutted between the front end convex step (21) and the rear end convex step (11).

6. A nozzle for foaming co-injection according to claim 3, characterized in that: The number of the cortex inlet grooves (44) and the cortex radial feed holes (412) are both multiple and arranged one by one. Each of the cortex inlet grooves (44) is circumferentially arranged on the outer wall of the valve core (4), and each of the cortex radial feed holes (412) is circumferentially arranged on the first valve section (41).

7. A nozzle for foaming co-injection according to claim 2, characterized in that: The limiting flange (431) is provided with an inclined abutment surface (4311) on a side close to the nozzle body (1), and the end of the nozzle body (1) is provided with an abutment guide surface (12) matching the inclined abutment surface (4311).

8. The nozzle for foaming co-injection according to claim 1, characterized in that: The diameter of the nozzle head (2) gradually decreases at an end away from the nozzle body (1).

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