Injection molding device for automotive lighted trim

Abstract

The application discloses a kind of injection molding device for automobile luminous decoration parts, relating to the technical field of injection molding device.The operation platform is slidably connected with symmetrically distributed sliding frame, the sliding frame is fixedly connected with mold, symmetrically distributed mold forms injection molding cavity, one side of the mold is fixedly connected with injection tube communicated with the injection molding cavity, the mold close to the injection tube is provided with exhaust hole for exhaust, the side of the mold away from the injection molding cavity is slidably connected with push disc, the push disc and adjacent mold form cooling cavity, the mold is fixedly connected and communicated with symmetrically distributed liquid guide pipe, the liquid guide pipe close to the operation platform is communicated with liquid storage sac through catheter.The cooling liquid stored in cooling cavity is discharged into liquid storage sac by moving push disc before injection molding, so as to avoid the cooling of mold by the cooling liquid remaining in cooling cavity, ensure the fluidity of melt in injection molding cavity, and facilitate the forming of decoration parts.

Description

Technical Field

[0001] This invention relates to the field of injection molding equipment technology, and in particular to an injection molding device for automotive luminous decorative parts. Background Technology

[0002] Illuminated automotive decorative parts (such as illuminated signs, decorative strips, and light guides) are important components for enhancing the technological feel and brand recognition of a car's appearance. These parts are usually made of highly transparent or specific optical properties polymer materials (such as PMMA and PC) through injection molding. They integrate LED light sources inside or on the side. The injection-molded parts are required to have extremely high transparency, surface smoothness, and no internal defects to ensure that the light can be transmitted evenly and efficiently to achieve the expected luminous effect.

[0003] In existing technologies, the injection molding process involves injecting molten plastic into the cavity of a mold, which is then cooled, solidified, and ejected to obtain the product. To control the production cycle and ensure part shaping, existing injection molding equipment typically has cooling channels or cooling cavities inside the mold for the flow of coolant (usually water or oil). During injection molding, the role of the cooling system is to rapidly and uniformly cool the molten plastic after it fills the cavity, thereby shortening the molding cycle and reducing part deformation. However, during the injection of molten plastic into the mold cavity, although the coolant pumping system is not activated, keeping the coolant in the cooling channels relatively still, the temperature of the coolant itself is much lower than that of the mold and the molten plastic. This causes the temperature at the leading edge of the molten plastic to drop too quickly during the filling process, increasing viscosity and reducing fluidity. This reduced fluidity prevents the melt from completely filling the delicate and complex structures (such as microstructures used for light distribution) in the mold cavity, resulting in incomplete filling and severely affecting the appearance and optical properties of the product. Summary of the Invention

[0004] To overcome the drawback that the coolant remaining in the cooling chamber during the injection molding process still cools the mold, thereby reducing the fluidity of the melt and affecting the appearance and optical performance of the product, this invention provides an injection molding device for automotive luminous decorative parts.

[0005] The technical solution is as follows: An injection molding device for automotive luminous decorative parts includes an operating table, on which symmetrically distributed sliding frames are slidably connected. The operating table is provided with a first power module for moving the symmetrically distributed sliding frames. A mold is fixedly connected to each sliding frame. The symmetrically distributed molds cooperate to form an injection cavity. An injection tube communicating with the injection cavity is fixedly connected to one side of the mold. An exhaust hole for venting is provided on the mold near the injection tube. A push plate is slidably connected to the side of the mold away from the injection cavity. The injection tube and the adjacent push plate are slidably connected. A second power module for moving the push plate is fixedly connected to the sliding frame. The push plate and the adjacent mold cooperate to form a cooling cavity. A symmetrically distributed liquid guide tube is fixedly connected to and communicates with the mold. The liquid guide tube near the operating table is connected to a liquid reservoir via a conduit.

[0006] As an improvement to the above solution, the push plate is fixedly connected to a connecting plate that is slidably connected to the injection tube. The connecting plate is made of a deformable material and is embedded with equally spaced limiting posts. The equally spaced limiting posts squeeze the adjacent connecting plates to divide the cooling chamber into equally spaced cooling channels. The liquid guide tube is connected to the equally spaced cooling channels in the adjacent cooling chambers. The push plate is provided with equally spaced mounting grooves that correspond one-to-one with the limiting posts on the adjacent connecting plates.

[0007] As an improvement to the above solution, the depth of the mounting groove is greater than the width of the limiting post.

[0008] As an improvement to the above solution, the mold near the injection tube is fixedly connected to a sealing sleeve by an L-shaped plate. The sealing sleeve is slidably connected to a pressure shell that passes through the vent hole and extends into the injection cavity. The pressure shell is provided with a vent hole and a temperature sensing cavity. The pressure shell is fixedly connected to a sealing plug that slides in a sealing manner with the sealing sleeve. The pressure shell is provided with a through hole that communicates with the temperature sensing cavity.

[0009] As an improvement to the above scheme, the temperature sensing cavity is filled with a fluid that expands when heated.

[0010] As an improvement to the above solution, the flow area of ​​the air guide hole is smaller than the flow area between the exhaust hole and the pressure shell.

[0011] As an improvement to the above solution, the diameter of the pressure shell on the side near the injection cavity is equal to the diameter of the vent hole.

[0012] As an improvement to the above solution, a spring is fixedly connected between the sealing plug and the sealing sleeve.

[0013] As an improvement to the above solution, the height of the injection tube on the side away from the injection cavity gradually decreases from the side closer to the mold to the side farther away from the mold.

[0014] As an improvement to the above solution, a frustum-shaped annular surface is provided on the inner wall of the injection tube near the mold. Symmetrically distributed elastic sheets are fixed to the frustum-shaped annular surface. The symmetrically distributed elastic sheets are jointly fixed to a plug for sealing the injection tube. The diameter of the plug is larger than the minimum diameter of the frustum-shaped annular surface.

[0015] This invention has the following advantages: Before injection molding, the coolant stored in the cooling chamber is drained into the reservoir by moving the push plate, thereby preventing the coolant remaining in the cooling chamber from cooling the mold, ensuring the fluidity of the melt in the injection chamber, and facilitating the forming of the decorative parts. Furthermore, the mold is insulated by the connecting plate fitting against it, reducing the rate of heat loss during injection molding. When the injection chamber is not fully filled with melt, venting occurs through the gap between the pressure shell and the vent hole. As the injection chamber gradually fills with melt, venting occurs through the vent hole, ensuring rapid melt injection while preventing melt overflow. The injection tube design allows melt that has not entered the injection chamber to flow back, reducing the amount of melt remaining in the injection tube and preventing melt solidification from affecting subsequent injection processes. After the injection process is completed, the injection tube is sealed using a plug and an elastic sheet to prevent melt from flowing back into the injection tube from the injection chamber. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0017] Figure 2 This is a three-dimensional structural diagram of the liquid guiding tube and the liquid storage bladder of the present invention;

[0018] Figure 3 This is a three-dimensional structural cross-sectional view of the sliding frame and mold of the present invention;

[0019] Figure 4 This is a three-dimensional structural cross-sectional view of the push plate and connecting plate of the present invention;

[0020] Figure 5 For the present invention Figure 3 Enlarged view of the 3D structure at point A;

[0021] Figure 6 This is a three-dimensional structural cross-sectional view of the sealing sleeve and pressure-bearing shell of the present invention;

[0022] Figure 7 This is a three-dimensional structural diagram of the plug and elastic sheet of the present invention.

[0023] The following are the labels in the diagram: 1. Operating table, 111. Injection cavity, 2. Sliding frame, 3. Mold, 31. Liquid guide tube, 301. Vent hole, 302. Cooling cavity, 4. Injection tube, 401. Tabletop toroidal surface, 5. Push plate, 51. Liquid reservoir, 501. Mounting groove, 6. Connecting plate, 7. Limiting post, 8. Sealing sleeve, 9. Pressure shell, 901. Air guide hole, 902. Temperature sensing cavity, 903. Through hole, 10. Sealing plug, 11. Spring, 12. Plug head, 13. Elastic sheet. Detailed Implementation

[0024] The above solution will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. The implementation conditions used in the embodiments may be further adjusted according to the conditions of specific manufacturers. Implementation conditions not specified are generally those in routine experiments. In the following embodiments, only a disc-shaped ornament is used as an example.

[0025] Example 1

[0026] Existing injection molding equipment typically has channels or cavities on the mold for coolant to flow through. During the injection process, although the coolant in the cooling channel or cavity is in a static state, its low temperature will still lower the temperature of the mold, resulting in a decrease in the temperature of the molten material and a decrease in its fluidity, thus affecting the quality of the molded product.

[0027] An injection molding device for automotive illuminated decorative parts, such as Figures 1-5As shown, the system includes an operating platform 1, with two symmetrically distributed sliding frames 2 slidably connected to the platform 1. The platform 1 is equipped with a first power module for moving the two sliding frames 2. The first power module is an electric slide rail (not shown in the figure) mounted on the platform 1. The electric slide rail has two electric sliders fixedly connected to adjacent sliding frames 2. A mold 3 is fixedly connected to the middle of each sliding frame 2. The two molds 3 cooperate to form an injection cavity 111. An injection tube 4, communicating with the injection cavity 111, is fixedly connected to the right mold 3. An infusion pump (not shown in the figure) is connected to the injection mold. The infusion pump draws the melt from the melt container and enters the injection cavity 111 through the injection tube 4. An vent 301 for venting is provided on the upper side of the right mold 3. A push plate 5 is slidably connected to the side of the mold 3 away from the injection cavity 111. A second power module for moving the push plate 5 is fixedly connected to the sliding frame 2. The second power module includes an electric push rod mounted on the sliding frame 2. The telescopic end of the electric push rod is fixedly connected to the push plate 5. The injection tube 4 and the adjacent push plate 5 are slidably connected. The push plate 5 and the adjacent mold are connected... 3. A cooling chamber 302 is formed by the mold 3. Two liquid guide pipes 31 are fixedly connected and symmetrically distributed vertically. The lower liquid guide pipe 31 is connected to a liquid reservoir 51 through a conduit. A connecting plate 6 is fixedly connected to the injection tube 4 and is slidably connected to the push plate 5. The connecting plate 6 is made of a deformable material and has equidistant limiting posts 7 embedded in it. The equidistant limiting posts 7 press against the adjacent connecting plates 6 to divide the cooling chamber 302 into spaced cooling channels. The liquid guide pipe 31 consists of a horizontal pipe and equidistant vertical pipes. The vertical pipes of the liquid guide pipe 31 are connected to the... The adjacent cooling channels in the adjacent cooling cavity 302 are connected. The push plate 5 is provided with mounting grooves 501 that are evenly distributed front and back and correspond one-to-one with the upper limit posts 7 of the adjacent connecting plate 6. The depth of the mounting groove 501 is greater than the width of the limit post 7, so that the limit post 7 can squeeze the connecting plate 6 into the mounting groove 501. The material of the connecting plate 6 is rubber with a closed-cell foam structure, which has good heat insulation performance. When the connecting plate 6 is close to the adjacent mold 3, the connecting plate 6 insulates the adjacent mold 3, thereby reducing the heat loss in the injection cavity 111 during the injection molding process.

[0028] When this injection molding device is needed to injection mold automotive illuminated trim parts, the operator activates the first power module to move the two molds 3 closer together. Figure 1In the indicated state, the operator stops the first power module, and the two molds 3 form the injection cavity 111. Then, the coolant remaining in the cooling cavity 302 is discharged. The specific operation is as follows: The operator starts the two second power modules, causing the two push plates 5 to move closer to each other. Taking the left push plate 5 as an example, the push plate 5 moves the connecting plate 6 to the right. The deformation of the part of the connecting plate 6 near the right side of the limiting post 7 gradually recovers, while the deformation of the part of the connecting plate 6 near the left side of the limiting post 7 gradually intensifies. The part of the connecting plate 6 near the left side of the limiting post 7 is gradually squeezed by the limiting post 7 and inserted into the adjacent mounting groove 501. During the process of the connecting plate 6 moving to the right, the connecting plate 6 squeezes the coolant in the cooling cavity 302. The coolant in the cooling cavity 302 flows downward through the lower liquid guide pipe 31 and the conduit into the reservoir 51. When expansion occurs and the volume increases, and the right side of the connecting plate 6 is tightly attached to the mold 3, the coolant in the cooling cavity 302 is completely discharged, preventing the coolant in the cooling cavity 302 from continuing to cool the mold 3 during subsequent injection into the injection cavity 111. At this time, the operator stops the second power module. Since the connecting plate 6 is tightly attached to the mold 3 and the material of the connecting plate 6 is rubber with a closed-cell foam structure, it has good heat insulation performance, thereby reducing the heat loss in the injection cavity 111 during the injection process, thereby improving the fluidity of the melt and ensuring that the entire cavity of the injection cavity 111 is completely filled (the part between the injection cavity 111 and the cooling cavity 302 of the existing mold 3 will use a material with high thermal conductivity, so the connecting plate 6 is used to insulate the part between the injection cavity 111 and the cooling cavity 302 from heat).

[0029] After the connecting plate 6 is attached to the mold 3, the operator injects melt into the injection cavity 111 through the injection tube 4. As the melt is continuously injected into the injection cavity 111, the gas in the injection cavity 111 is discharged through the vent 301. When the injection cavity 111 is full of melt, the operator stops injecting melt into the injection cavity 111. Then the operator activates the two second power modules to drive the two push plates 5 to move away from each other. Taking the left push plate 5 as an example, the push plate 5 drives the connecting plate 6 to move to the left. As the push plate 5 moves to the left, the pressure in the cooling cavity 302 decreases, and the coolant in the reservoir 51 is drawn into the cooling cavity 302 through the conduit and the liquid guide tube 31. During the process of the connecting plate 6 moving to the left, the deformation of the positions of the left and right sides of the connecting plate 6 near the limiting post 7 gradually recovers. The limiting post 7 moves to the right relative to the connecting plate 6. When the limiting post 7 is located in the middle of the connecting plate 6, the state is as follows. Figure 3 and Figure 4 As shown, the operator stopped the second power module.

[0030] In the state such as Figure 3 and Figure 4As shown, coolant is injected into the upper guide pipe 31. After entering the cooling chamber 302, the injected coolant flows downward along the cooling channel to cool the mold 3. The cooling channel guides the coolant to prevent it from lingering in the cooling chamber 302, ensuring uniform cooling of the mold 3. After heat exchange, the coolant in the cooling chamber 302 is discharged through the lower guide pipe 31. The discharged coolant is cooled by the external cooling circulation system and then re-enters the upper guide pipe 31. When the melt in the injection cavity 111 solidifies, the coolant stops circulating. The operator starts the first power module to move the left sliding frame 2 to the left. The sliding frame 2 moves the mold 3 and its parts to the left. The operator removes the decorative piece between the two molds 3, and then starts the first power module to move the sliding frame 2 to the left. Figure 1 As shown, this injection molding device has been used successfully. If injection molding is required again, the above steps are repeated. The finished part is then shaped using the following process:

[0031] 1. Single-color injection molded transparent PC material parts, the raw material plastic particles are dried at 120℃ for 4 hours, and the injection molded parts are free from defects such as black spots, silver streaks, and yellowing.

[0032] 2. Spray laser-engraved black paint on the inner surface of the injection molded part. The inner surface of the part must be free of defects such as oil stains, foreign objects, and fingerprints. The masking fixture must have good masking performance. The thickness of the laser-engraved black paint is about 16μm. The leveling temperature is 26±4℃ and the time is 10min. The drying temperature is 80℃ and the drying time is 35min.

[0033] 3. Laser stripping uses ultraviolet laser engraving equipment with a special contour-following fixing fixture. The laser engraving and marking speed is 1500mm / s, the air jump speed is 8000mm / s, and the current is 8A (key process).

[0034] 4. Apply a soft-touch paint coating to the front of the material, with a coating thickness of approximately 40μm. The leveling temperature is 26±4℃ for 16 minutes, and the drying temperature is 85℃ for 50 minutes. After drying, a soft-touch surface is achieved that is not prone to fingerprints (key process, paint).

[0035] Example 2

[0036] The existing vent holes have small diameters to ensure that the melt solidifies quickly when it moves to the vicinity of the vent hole, thereby preventing the melt in the injection cavity from overflowing through the vent hole. However, the small diameter of the vent hole will result in a slow gas discharge rate in the injection cavity, leading to low injection efficiency. On the other hand, simply increasing the diameter of the vent hole will cause the melt to overflow.

[0037] Based on Example 1, an injection molding device for automotive luminous decorative parts, such as... Figure 3 , Figure 5 and Figure 6As shown, a sealing sleeve 8 located above the vent 301 is fixed to the upper side of the right mold 3 via an L-shaped plate. The sealing sleeve 8 is slidably connected to a pressure shell 9 that passes through the vent 301 and extends into the injection cavity 111. The pressure shell 9 is provided with a vent hole 901 and a temperature sensing cavity 902. A sealing plug 10 that slides and seals with the sealing sleeve 8 is fixed to the upper side of the pressure shell 9. A through hole 903 communicating with the temperature sensing cavity 902 is provided on the upper side of the pressure shell 9. The temperature sensing cavity 902 is filled with a thermally expanding fluid. The temperature of the thermally expanding fluid in the temperature sensing cavity 902 rises. After passing through the through hole 903, the gas enters the lower side of the sealing plug 10 inside the sealing sleeve 8, thereby pushing the sealing plug 10 to drive the pressure shell 9 to move upward. The flow area of ​​the vent hole 901 is smaller than the flow area between the exhaust hole 301 and the upper side of the pressure shell 9. The lower diameter of the pressure shell 9 is larger than the upper diameter. The lower diameter of the pressure shell 9 is equal to the diameter of the exhaust hole 301. A spring 11 is fixed between the sealing plug 10 and the sealing sleeve 8. The spring force of the spring 11 is small and is only used to push the sealing plug 10 to drive the pressure shell 9 to move downward. It will not generate a large resistance to the upward movement of the pressure shell 9.

[0038] During the injection of melt into the injection cavity 111, the gas in the injection cavity 111 flows upward through the gap between the pressure shell 9 and the vent 301. At this time, the gas flow area is large, which facilitates the rapid discharge of gas and the injection of melt. The melt flows upward and gradually fills the injection cavity 111. When the melt comes into contact with the lower side of the pressure shell 9, the temperature of the melt causes the lower side of the pressure shell 9 to heat up rapidly. The heated fluid in the pressure shell 9 expands in volume after being heated, and the expanded gas enters the sealing sleeve 8 below the sealing plug 10 through the through hole 903, thereby pushing the sealing plug 10 to move upward. Spring 1 1. When compressed, the sealing plug 10 moves the pressure-bearing shell 9 upward. After the lower side of the pressure-bearing shell 9 blocks the vent 301, the injection cavity 111 is not yet filled with melt. Subsequently, the gas discharged from the injection cavity 111 is discharged through the vent 901. When the melt enters the vent 901, it solidifies, and the injection process is completed. When the trim is gradually cooled, the temperature of the heated fluid in the temperature sensing cavity 902 decreases, and the pressure decreases. When the trim is removed, the spring 11, which is in a compressed state, releases its elasticity, causing the sealing plug 10 to move downward. The sealing plug 10 moves the pressure-bearing shell 9 downward to reset.

[0039] Example 3

[0040] Based on Example 2, an injection molding device for automotive luminous decorative parts, such as... Figure 4 and Figure 7As shown, the injection tube 4 consists of a horizontal part and an inclined part. The left side of the injection tube 4 is higher than the right side. The inner wall of the left side of the injection tube 4 is provided with a frustum-shaped annular surface 401. The frustum-shaped annular surface 401 is fixed with symmetrically distributed elastic plates 13. The symmetrically distributed elastic plates 13 are jointly fixed with a plug 12 for sealing the injection tube 4. The diameter of the plug 12 is larger than the minimum diameter of the frustum-shaped annular surface 401.

[0041] During the injection of molten material into the injection tube 4, the molten material pushes the stopper 12 to the left, causing the elastic sheet 13 to deform. The stopper 12 no longer seals the injection tube 4, and the molten material in the injection tube 4 enters the injection cavity 111. After injection is completed, the injection of molten material into the injection tube 4 stops. Since the left side of the inclined part of the injection tube 4 is higher than the right side, the molten material remaining in the injection tube 4 will flow back. At the same time, the elastic sheet 13 resets and drives the stopper 12 to move to the right to continue sealing the injection tube 4, preventing the molten material in the injection cavity 111 from flowing back. By discharging the molten material in the injection tube 4, the molten material is prevented from staying and solidifying in the injection tube 4 for a long time, which would affect the subsequent injection process. Moreover, the elastic sheet 13, as a deformable part, is located on the right side of the stopper 12, preventing the molten material from solidifying and wrapping the elastic sheet 13, thus making the elastic sheet 13 unusable.

[0042] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An injection molding device for automotive luminous decorative parts, comprising an operating table (1), wherein the operating table (1) is slidably connected to symmetrically distributed sliding frames (2), the operating table (1) is provided with a first power module for moving the symmetrically distributed sliding frames (2), the sliding frames (2) are fixedly connected to molds (3), the symmetrically distributed molds (3) cooperate to form an injection cavity (111), one side of the mold (3) is fixedly connected to an injection tube (4) communicating with the injection cavity (111), and the mold (3) near the injection tube (4) is provided with an exhaust hole (301) for exhaust, characterized in that, The mold (3) is slidably connected with a push disc (5) away from the injection cavity (111), the injection pipe (4) is slidably connected with the adjacent push disc (5), the sliding frame (2) is fixedly connected with a second power module for driving the push disc (5) to move, the push disc (5) and the adjacent mold (3) cooperate to form a cooling cavity (302), the mold (3) is fixedly connected and communicated with symmetrically distributed liquid guide pipes (31), the liquid guide pipe (31) close to the operation table (1) is communicated with a liquid storage bag (51) through a conduit. The push disc (5) is fixedly connected with a connecting disc (6) slidably connected with the injection pipe (4), the connecting disc (6) is made of a deformable material, the connecting disc (6) is embedded with equally spaced limiting columns (7), and the equally spaced limiting columns (7) press the adjacent connecting disc (6) to divide the cooling cavity (302) into equally spaced cooling channels, the liquid guide pipe (31) is in communication with the equally spaced cooling channels in the adjacent cooling cavity (302), and the push disc (5) is provided with equally spaced mounting grooves (501) corresponding to the limiting columns (7) on the adjacent connecting disc (6).

2. The injection molding device for the light-emitting decorative part of the automobile according to claim 1, wherein The depth of the mounting groove (501) is greater than the width of the limiting column (7).

3. The injection molding device for the light-emitting decorative part of the automobile according to claim 1, wherein, The mold (3) close to the injection pipe (4) is fixedly connected with a sealing sleeve (8) through an L-shaped plate, the sealing sleeve (8) is sealingly and slidably connected with a pressure shell (9) penetrating through the exhaust hole (301) and extending into the injection cavity (111), the pressure shell (9) is provided with a gas guide hole (901), the pressure shell (9) is provided with a temperature sensing cavity (902), the pressure shell (9) is fixedly connected with a sealing plug (10) sealingly and slidably connected with the sealing sleeve (8), and the pressure shell (9) is provided with a through hole (903) in communication with the temperature sensing cavity (902).

4. The injection molding device for the light-emitting decorative part of the automobile according to claim 3, wherein, The temperature sensing cavity (902) is filled with a heat-expandable fluid.

5. The injection molding device for the light-emitting decorative part of the automobile according to claim 3, characterized in that, The flow area of the gas guide hole (901) is smaller than the flow area between the exhaust hole (301) and the pressure shell (9).

6. The injection molding device for the light-emitting decorative part of an automobile according to claim 3, wherein The diameter of the pressure shell (9) close to the injection cavity (111) is equal to the diameter of the exhaust hole (301).

7. The injection molding device for the light-emitting decorative part of the automobile according to claim 3, wherein, The sealing plug (10) and the sealing sleeve (8) are fixedly connected with a spring (11).

8. The injection molding device for automotive lighted trim of claim 1, wherein, The height of the injection pipe (4) away from the injection cavity (111) gradually decreases from the side close to the mold (3) to the side away from the mold (3).

9. The injection molding device for automotive lighted trim of claim 8, wherein, The inner wall of the injection pipe (4) close to the mold (3) is provided with a frustum ring surface (401), the frustum ring surface (401) is fixedly connected with symmetrically distributed elastic sheets (13), and the symmetrically distributed elastic sheets (13) are jointly fixedly connected with a plug head (12) for plugging the injection pipe (4), and the diameter of the plug head (12) is greater than the minimum diameter of the frustum ring surface (401).

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