Large-size composite material flexible joint, rapid forming method and forming mold

Abstract

The invention provides a large-size composite material flexible joint which comprises a fixed joint and a movable joint, a plurality of layers of reinforcing parts are arranged between the fixed joint and the movable joint, a plurality of through holes are formed in the reinforcing parts, and the through holes are communicated with the fixed joint and the movable joint. The fixed connector and the reinforcing pieces, the movable connector and the reinforcing pieces and every two adjacent reinforcing pieces are connected into a whole through an elastic layer, and the elastic layers are formed after flowing rubber is heated and vulcanized. The interface bonding strength between each part and the elastic layer is far higher than that of a traditional bonding forming flexible joint, the composite material is good in internal quality and excellent in mechanical property, the stability and reliability of the flexible joint are remarkably improved, and the flexible joint has the advantages of being large in size, light in weight, high in structural strength, low in torque, good in swing performance, short in production period and the like. And the product design performance requirements are met.

Description

Technical Field

[0001] The invention relates to the technical field of flexible swing nozzles, and in particular to a large-size composite material flexible joint, a rapid prototyping method and a prototyping die. Background Art

[0002] In aerospace production, the key technology of advanced solid launch vehicles is the vector flexible swing nozzle of high-maneuverability solid rocket engines. The flexible swing nozzle is a key component for rockets to obtain vector thrust, and the flexible joint is an important part of the solid rocket engine flexible swing nozzle vector control system, which directly affects the engine pitch, yaw or roll attitude and orbit control accuracy. Therefore, the vector control performance of the swing nozzle flexible joint directly affects the maneuverability of the solid rocket engine, and the manufacture of a new generation of lightweight omnidirectional vector flexible joints is a key technical difficulty of high-performance vector solid rocket engines.

[0003] Flexible joints are generally composed of fixed joints, multi-layer thin-walled ball ring reinforcements (generally 3 to 4 mm thick), elastic parts, and movable joints. The fixed joints, reinforcements, and movable joints of traditional flexible joints are generally made of metal materials. With the development of composite material technology, the fixed joints, reinforcements, and movable joints of large-size flexible joints are made by composite material molding to reduce the weight of the flexible joint and improve the performance of the engine. As an important component, the molding process technology of flexible joints is relatively difficult. There are many ways to mold flexible joints, such as hot and cold bonding molding, integrated hot bonding molding, injection molding, etc. In the traditional molding process, butadiene-based low-temperature resistant elastomers with good fluidity and long scorch time are generally selected as rubber materials. By designing a suitable flexible joint bonding molding mold, the fixed rear joint, multi-layer reinforcements, and movable inverted cone shells are stacked layer by layer on the bonding mold, and appropriate process parameters are set. The hot press vulcanizer is used for molding, and the flexible joint is hot vulcanized at high temperature to form a flexible joint. After that, the flexible joint geometric dimensions and swing performance tests are performed. At present, the production of traditional flexible joints mostly adopts the bonding and compression molding method, which has many manual processes, long production cycles, and great difficulty in controlling quality consistency. For the new generation of large-size composite flexible joints, the diameter is generally above φ500. If the traditional molding process is used, the production cycle is longer. In addition, due to the differences in the composite molding process, the quality stability is worse. Especially for fixed joints and movable joints with large thickness and complex shapes, composite joints formed by traditional compression molding or cloth tape paving have problems such as low preparation efficiency, poor quality stability, and poor structural mechanical properties. How to quickly and efficiently produce qualified composite flexible joints faces many challenges for existing technologies. Summary of the invention

[0004] The purpose of the present invention is to address the defects of the prior art and provide a large-size composite material flexible joint, a rapid prototyping method and a molding mold. The interface bonding strength between each part and the elastic layer is much higher than that of the traditional adhesive molding flexible joint. The internal quality of the composite material is good, the mechanical properties are excellent, the stability and reliability of the flexible joint are significantly improved, and it has the advantages of large size, light weight, high structural strength, good low-torque swing performance, short production cycle, etc., which meet the product design performance requirements.

[0005] In order to solve the above technical problems, in the first aspect, the present invention provides a large-size composite material flexible joint, including a fixed joint and a movable joint, a multi-layer reinforcement is arranged between the fixed joint and the movable joint, a plurality of through holes are opened on the reinforcement, the fixed joint and the reinforcement, the movable joint and the reinforcement, and two adjacent reinforcements are connected as a whole through an elastic layer, and the elastic layer is formed by heating and vulcanizing fluid rubber.

[0006] Furthermore, a plurality of grooves are provided on the surfaces where the fixed joint and the movable joint are connected to the reinforcing member, and elastic layers are arranged in the grooves.

[0007] Furthermore, the multiple layers of reinforcement members are concentric thin-walled spherical ring sheets.

[0008] In a second aspect, the present invention provides a rapid prototyping method for a large-size composite material flexible joint, comprising:

[0009] Preparation of fixed joints and movable joints;

[0010] The reinforcement is prepared by laying up layers;

[0011] Assemble the movable joint, the multi-layer reinforcement, and the fixed joint in the inner cavity of the forming mold in order from bottom to top;

[0012] The heated fluid rubber is poured into the inner cavity of the molding mold through the pouring port and runner of the molding mold by the transfer method, and the inner cavity of the molding mold is evacuated through the vacuum nozzle at the bottom of the molding mold to ensure that the rubber completely fills the inner cavity;

[0013] After the injection is completed, the rubber is heated and vulcanized to form an elastic layer.

[0014] Furthermore, the method for preparing the fixed joint and the movable joint comprises:

[0015] The fibers are knitted according to a three-dimensional model of fixed joints and movable joints;

[0016] Resin impregnation is used;

[0017] Hot pressing curing molding, machining;

[0018] A threaded hole is processed on the end face of the fixed joint, and a wire thread sleeve is bonded and embedded in the threaded hole using thread locking adhesive.

[0019] Furthermore, the method for preparing a reinforcement member by laying layers includes:

[0020] Carbon fiber unidirectional cloth / epoxy resin prepreg is used to cover the mold surface of the reinforcement. After the multi-layer reinforcement is covered, it is cured in an autoclave and evenly distributed through holes are processed on the reinforcement.

[0021] Furthermore, before assembling the movable joint, the multi-layer reinforcement and the fixed joint to the molding die, all surfaces of the fixed joint, the reinforcement and the movable joint in contact with the elastic layer are subjected to sandblasting and roughening treatment and are brushed with glue.

[0022] In a third aspect, the present invention provides a molding mold, comprising a template and a glue injection plate, the template comprising an upper template and a lower template, the upper end faces of the upper template and the lower template are detachably fixedly connected, the inner side face of the lower template is used to fit with the outer side face of the movable joint, support frames are evenly spaced on the inner side face of the upper template, and plug blocks are evenly spaced from top to bottom on the side of the support frame away from the upper template, the plug blocks are used to be inserted between two adjacent layers of reinforcement members to form a glue injection space between the two adjacent layers of reinforcement members, the glue injection plate is detachably fixedly connected to the upper end face of the upper template, a glue injection port is provided on the glue injection plate, an inner core mold is arranged in the template, an inner cavity is formed between the inner core mold and the template, the inner core mold is detachably fixedly connected to the lower template, a first flow channel is formed between the top of the inner core mold and the glue injection plate, and a second flow channel is formed between the side face of the inner core mold and the upper template.

[0023] Furthermore, the inner core mold includes an upper inner core mold, a middle inner core mold, and a lower inner core mold; the lower inner core mold is detachably fixedly connected to the lower mold plate; the lower inner core mold is used to limit the inner side surface of the movable joint and the inner side surface of the reinforcement; the middle inner core mold is detachably fixedly connected to the lower inner core mold; the middle inner core mold is used to limit the inner side surface of the fixed joint; the upper inner core mold is detachably fixedly connected to the middle inner core mold; a first flow channel is formed between the top of the upper inner core mold and the glue injection plate; a second flow channel is formed between the side surface of the upper inner core mold and the upper mold plate.

[0024] Furthermore, an air suction hole is provided at a position of the lower template close to the inner wall, and the air suction hole is used to evacuate the inner cavity.

[0025] Furthermore, it includes a glue injection tool, which includes a shell, a glue outlet is opened at the bottom of the shell, a heating wire is arranged in the shell, the heating wire is used to heat the rubber in the shell into a fluid state, and a piston is also arranged in the shell, the piston is used to push the fluid rubber out of the glue outlet.

[0026] The beneficial effects of the present invention are:

[0027] 1. The present invention opens through holes on the reinforcement and fills elastic layers in the through holes, between the fixed joint and the reinforcement, between the movable joint and the reinforcement, and between two adjacent reinforcements, so that all the elastic layers can form a whole, which not only solves the problem of bonding strength of the bonding interface between the materials, but also significantly improves the stability of the flexible joint.

[0028] 2. The present invention provides grooves on the fixed joint and the movable joint, thereby enhancing the bonding strength of the interface between the fixed joint and the movable joint and the elastic layer.

[0029] 3. The fixed joints and movable joints of the present invention are prepared by fiber knitting, resin impregnation and hot pressing curing. Compared with traditional processes, they have the advantages of low cost, high molding efficiency, good internal quality stability, low mold cost, and excellent comprehensive mechanical properties of materials.

[0030] 4. The reinforcement of the present invention is formed by laying out carbon fiber layers and heating and curing, so that the mechanical properties of the reinforcement are better, and the problem of low strength of thin-walled composite reinforcement is solved.

[0031] 5. The present invention adopts the transfer injection method to inject rubber, that is, using the injection tooling with heating capability to directly inject the fluid rubber into the inner cavity of the molding mold, which greatly improves the production efficiency of flexible joint molding. Compared with the traditional injection molding process, it does not require injection machine equipment and complex molding molds, and has high molding efficiency and low production cost.

[0032] 5. The present invention provides an air extraction hole on the lower template so that the rubber can fill the inner cavity of the molding mold, ensuring that the elastic layer can fill the space between the fixed joint and the reinforcement, between the movable joint and the reinforcement, and between two adjacent reinforcements.

[0033] 6. The present invention provides a support frame so that the multi-layer reinforcements are evenly distributed, ensuring that there is a full elastic layer between any two adjacent reinforcements. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic structural diagram of the large-size composite material flexible joint of the present invention.

[0035] Figure 2 It is a schematic diagram of the grooves of the fixed joint and the movable joint of the present invention;

[0036] Figure 3 It is a schematic diagram of the structure of the reinforcement member of the present invention;

[0037] Figure 4 This is a schematic diagram of the present invention when using a molding mold to perform glue injection;

[0038] Figure 5 It is a structural schematic diagram of the support frame of the present invention.

[0039] Figure numerals: fixed joint 1; wire thread sleeve 2; reinforcement 3; elastic layer 4; movable joint 5; groove 6; forming mold 7; upper template 71; lower template 72; upper inner core mold 73; middle inner core mold 74; lower inner core mold 75; glue injection plate 76; glue injection port 77; support frame 78; vacuum nozzle 79; glue injection tooling 8; butadiene-based rubber 9. DETAILED DESCRIPTION

[0040] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0041] like Figure 1 As shown, the present invention provides a large-size composite material flexible joint, including a fixed joint 1 and a movable joint 5, a multi-layer reinforcement 3 is arranged between the fixed joint 1 and the movable joint 5, a plurality of through holes are provided on the reinforcement 3, the fixed joint 1 and the reinforcement 3, the movable joint 5 and the reinforcement 3, and two adjacent reinforcements 3 are connected as a whole through an elastic layer 4, and the elastic layer 4 is formed by heating and vulcanizing fluid rubber. A wire screw sleeve 2 is arranged on the fixed joint 1.

[0042] It can be understood that the present invention opens through holes on the reinforcement 3, fills the elastic layer 4 in the through holes, between the fixed joint 1 and the reinforcement 3, between the movable joint 5 and the reinforcement 3, and between two adjacent reinforcements 3, so that all the elastic layers 4 can form a whole, which not only solves the problem of bonding strength of the bonding interface between the materials, but also significantly improves the stability of the flexible joint.

[0043] Furthermore, if Figure 2 As shown, the surfaces where the fixed joint 1 and the movable joint 5 are connected to the reinforcement member 3 are provided with a plurality of grooves 6 , and the elastic layer 4 is arranged in the grooves 6 .

[0044] It can be understood that by providing the groove 6 , the bonding strength of the interface between the fixed joint 1 and the movable joint 5 and the elastic layer 4 is enhanced.

[0045] Furthermore, if Figure 3 As shown, the multi-layer reinforcement member 3 is a concentric thin-walled spherical ring sheet body with a wall thickness of 3 to 4 mm and 1 to 3 circles of through holes are provided thereon.

[0046] The rapid prototyping method of the large-size composite material flexible joint comprises:

[0047] S1, preparing the fixed joint 1 and the movable joint 5; specifically comprising:

[0048] Quartz fiber is used to knit according to the three-dimensional model of the fixed joint 1 and the movable joint 5 to form a knitted body, and the inner and outer surfaces of the knitted body are reserved with a 1-2 mm margin on one side based on the outline of the theoretical model of the parts;

[0049] The braided body is impregnated with phenolic resin, and the resin content of the braided body is measured by weighing method, which should be no less than 35%;

[0050] The braided body is placed in a special mold and formed by hot pressing and curing to form a blank. The hot pressing curing temperature is 160-170°C and the curing time is 6-8h.

[0051] The inner and outer surfaces of the blank are machined according to the part drawing. After the threaded hole is processed on the end face of the fixed joint 1, the wire screw sleeve 2 is bonded and embedded in the threaded hole with thread locking adhesive. Among them, the surfaces where the fixed joint 1 and the movable joint 5 contact the elastic layer 4 have grid-shaped grooves 6 with a depth of 1 to 2 mm.

[0052] S2, preparing a reinforcement 3 by laying layers;

[0053] The reinforcement 3 is prepared by laying. The reinforcement 3 is made of carbon fiber unidirectional cloth / epoxy resin prepreg and laid according to the mold surface. Generally, 8 to 12 pieces are laid. When laying, the inner and outer arc surfaces are laid according to the net size of the part thickness. A 1 to 2 mm margin is reserved at the exits of both ends of the reinforcement 3 to be removed by machining after curing. When laying, the fiber cloth tape should be flat, without wrinkles, overhead, bulging, etc. on the surface. After laying about 5 layers of fiber cloth tape, vacuum pre-pressing is used to ensure that the fiber is compact inside;

[0054] After the ply is completed, it is cured in an autoclave at a temperature of 140-150°C and a curing time of 2-3 hours;

[0055] Two circles of evenly distributed through holes with a diameter of 5 to 8 mm are processed on the reinforcement member 3.

[0056] S3, assembling the movable joint 5, the multi-layer reinforcement 3, and the fixed joint 1 in the inner cavity of the molding die 7 in order from bottom to top; specifically comprising:

[0057] Before assembling the movable joint 5, the multi-layer reinforcement 3, and the fixed joint 1 to the molding die 7, all surfaces of the fixed joint 1, the reinforcement 3, the movable joint 5 in contact with the elastic layer 4 are subjected to sandblasting and roughening treatment and brushed with glue. After the glue is cured for 48 hours, the movable joint 5, the reinforcement 3, and the fixed joint 1 are assembled in the inner cavity of the molding die 7 in order from bottom to top;

[0058] S4, using the transfer method, pouring the heated fluid rubber into the inner cavity of the molding mold 7 through the pouring port and the flow channel of the molding mold 7, and evacuating the mold cavity through the vacuum nozzle 79 at the bottom of the molding mold 7 to ensure that the rubber completely fills the inner cavity; specifically including:

[0059] The heated fluid butadiene-based rubber 9 is poured into the inner cavity of the molding mold 7 through the injection port 77 and the flow channel of the molding mold 7 by the transfer method, and the inner cavity of the molding mold is evacuated through the vacuum nozzle 79 at the bottom of the molding mold 7 to ensure that the butadiene-based rubber 9 completely fills the inner cavity.

[0060] S5, after the injection is completed, the rubber is heated and vulcanized to form an elastic layer 4. Specifically comprising:

[0061] After the injection is completed, it is placed under the hot press for vulcanization. The press is pressurized to 10-15MPa, heated to 140-150℃ and kept warm for 0.5-1h. After cooling with the furnace, the mold is disassembled and the flexible joint is taken out.

[0062] like Figure 4 As shown, the present invention also provides a molding die 7, including a template and a glue injection plate 76, the template includes an upper template 71 and a lower template 72, the upper template 71 and the upper end surface of the lower template 72 are detachably fixedly connected, the inner side surface of the lower template 72 is used to fit with the outer side surface of the movable joint 5, and the inner side surface of the upper template 71 is evenly spaced to arrange support frames 78, and the support frames 78 can be an integral structure with the upper template 71, such as Figure 5 As shown, the support frame 78 is provided with plug blocks evenly spaced from top to bottom on one side away from the upper template 71, and the plug blocks are used to be inserted between two adjacent layers of reinforcement members 3, so that a glue injection space is formed between the two adjacent layers of reinforcement members 3, and the glue injection plate 76 is detachably fixedly connected to the upper end surface of the upper template 71, and a glue injection port 77 is provided on the glue injection plate 76. An inner core mold is arranged in the template, and an inner cavity is formed between the inner core mold and the template, and the inner core mold is detachably fixedly connected to the lower template 72, a first flow channel is formed between the top of the inner core mold and the glue injection plate 76, and a second flow channel is formed between the side of the inner core mold and the upper template 71.

[0063] Furthermore, the inner core mold includes an upper inner core mold 73, a middle inner core mold 74, and a lower inner core mold 75. The lower inner core mold 75 is detachably fixedly connected to the lower mold plate 72, and the lower inner core mold 75 is used to limit the inner side surface of the movable joint 5 and the inner side surface of the reinforcement 3. The middle inner core mold 74 is detachably fixedly connected to the lower inner core mold 75, and the middle inner core mold 74 is used to limit the inner side surface of the fixed joint 1. The upper inner core mold 73 is detachably fixedly connected to the middle inner core mold 74, and a first flow channel is formed between the top of the upper inner core mold 73 and the glue injection plate 76, and a second flow channel is formed between the side surface of the upper inner core mold 73 and the upper mold plate 71.

[0064] Bolts are used to detachably fix the upper mold 71 and the lower mold 72 , the upper mold 71 and the glue injection plate 76 , the lower inner core mold 75 and the lower mold 72 , the upper inner core mold 73 and the middle inner core mold 74 , and the middle inner core mold 74 and the lower inner core mold 75 .

[0065] Furthermore, the lower template 72 is provided with an air extraction hole near the inner wall, and the air extraction hole is used to evacuate the inner cavity. A vacuum nozzle 79 is provided on the air extraction hole, and the vacuum nozzle 79 is used to connect a vacuum extraction device.

[0066] Furthermore, it includes a glue injection tool 8, which includes a shell, a glue outlet is opened at the bottom of the shell, a heating wire is arranged in the shell, the heating wire is used to heat the rubber in the shell into a fluid state, and a piston is also arranged in the shell, the piston is used to push the fluid rubber out of the glue outlet.

[0067] The method of using the molding die 7 is as follows: place the movable joint 5 on the inner side of the lower mold plate 72, install the lower inner core mold 75 on the lower mold plate 72, place the reinforcement pieces 3 one by one on the movable joint 5, and then install the upper mold plate 71 on the lower mold plate 72. During the installation process, use the plug of the support frame 78 on the upper mold plate 71 to separate all the reinforcement pieces 3, place the fixed joint 1 on the reinforcement pieces 3, and install the middle inner core mold 74, the upper inner core mold 73, and the glue injection plate 76 in sequence. Start preparing for glue injection, use the glue injection tool 8 to heat the rubber in the shell into a fluid state, align the glue outlet of the glue injection tool 8 with the glue injection port 77 of the glue injection plate 76, push the piston, and use the vacuum device to vacuum the inner cavity of the molding die 7 at the same time, so that the rubber fills the inner cavity.

[0068] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A large-size composite material flexible joint, characterized in that: The invention comprises a fixed joint (1) and a movable joint (5), wherein a multi-layer reinforcement member (3) is arranged between the fixed joint (1) and the movable joint (5), wherein a plurality of through holes are provided on the reinforcement member (3), and wherein the fixed joint (1) and the reinforcement member (3), the movable joint (5) and the reinforcement member (3), and two adjacent reinforcement members (3) are connected as a whole via an elastic layer (4), wherein the elastic layer (4) is formed by heating and vulcanizing a fluid rubber.

2. The large-size composite material flexible joint according to claim 1, characterized in that: The surfaces where the fixed joint (1) and the movable joint (5) are connected to the reinforcing member (3) are provided with a plurality of grooves (6), and the elastic layer (4) is arranged in the grooves (6).

3. A rapid prototyping method for a large-size composite material flexible joint according to claim 1 or 2, characterized in that: include: Prepare a fixed joint (1) and a movable joint (5); A reinforcement member (3) is prepared by layering; Assembling the movable joint (5), the multi-layer reinforcement (3), and the fixed joint (1) in the inner cavity of the molding die (7) in order from bottom to top; The heated fluid rubber is poured into the inner cavity of the molding die (7) through the pouring port and the flow channel of the molding die (7) by the transfer method, and the inner cavity of the molding die (7) is evacuated by the vacuum nozzle (79) at the bottom of the molding die (7) to ensure that the rubber completely fills the inner cavity; After the injection is completed, the rubber is heated and vulcanized to form an elastic layer (4).

4. The rapid prototyping method according to claim 3, characterized in that: The method for preparing the fixed joint (1) and the movable joint (5) comprises: The fibers are knitted according to a three-dimensional model of a fixed joint (1) and a movable joint (5); Resin impregnation is used; Hot pressing curing molding, machining; A threaded hole is processed on the end face of the fixed joint (1), and a wire thread sleeve (2) is bonded and embedded in the threaded hole using thread locking adhesive.

5. The rapid prototyping method according to claim 3, characterized in that: The method for preparing the reinforcement member (3) by layering comprises: Carbon fiber unidirectional cloth / epoxy resin prepreg is used to cover the mold surface of the reinforcement (3). After the multi-layer reinforcement (3) is covered, it is cured in an autoclave and uniformly distributed through holes are processed on the reinforcement (3).

6. The rapid prototyping method according to claim 3, characterized in that: Before assembling the movable joint (5), the multi-layer reinforcement (3) and the fixed joint (1) to the molding die (7), all surfaces of the fixed joint (1), the reinforcement (3) and the movable joint (5) in contact with the elastic layer (4) are subjected to sandblasting and roughening treatment and are coated with glue.

7. A molding die for the rapid prototyping method according to any one of claims 3 to 6, characterized in that: The invention comprises a template and a glue injection plate (76), wherein the template comprises an upper template (71) and a lower template (72), wherein the upper end surfaces of the upper template (71) and the lower template (72) are detachably fixedly connected, wherein the inner side surface of the lower template (72) is used to fit with the outer side surface of the movable joint (5), and support frames (78) are evenly arranged on the inner side surface of the upper template (71), and plug blocks are evenly arranged from top to bottom on a side of the support frame (78) away from the upper template (71), wherein the plug blocks are used to insert two adjacent layers of reinforcement members ( 3), so that a glue injection space is formed between two adjacent layers of reinforcement members (3), the glue injection plate (76) is detachably fixedly connected to the upper end surface of the upper template (71), a glue injection port (77) is provided on the glue injection plate (76), an inner core mold is arranged in the template, an inner cavity is formed between the inner core mold and the template, the inner core mold is detachably fixedly connected to the lower template (72), a first flow channel is formed between the top end of the inner core mold and the glue injection plate (76), and a second flow channel is formed between the side of the inner core mold and the upper template (71).

8. The molding die according to claim 7, characterized in that: The inner core mold comprises an upper inner core mold (73), a middle inner core mold (74), and a lower inner core mold (75); the lower inner core mold (75) is detachably fixedly connected to the lower mold plate (72); the lower inner core mold (75) is used to limit the inner side surface of the movable joint (5) and the inner side surface of the reinforcement member (3); the middle inner core mold (74) is detachably fixedly connected to the lower inner core mold (75); the middle inner core mold (74) is used to limit the inner side surface of the fixed joint (1); the upper inner core mold (73) is detachably fixedly connected to the middle inner core mold (74); a first flow channel is formed between the top end of the upper inner core mold (73) and the injection plate (76); and a second flow channel is formed between the side surface of the upper inner core mold (73) and the upper mold plate (71).

9. The molding die according to claim 7, characterized in that: The lower template (72) is provided with an air suction hole at a position close to the inner wall, and the air suction hole is used to evacuate the inner cavity.

10. The molding die according to claim 7, characterized in that: The invention comprises a glue injection tool (8), wherein the glue injection tool (8) comprises a shell, a glue outlet is provided at the bottom of the shell, a heating wire is arranged in the shell, the heating wire is used to heat the rubber in the shell into a fluid state, and a piston is also arranged in the shell, the piston is used to push the fluid rubber out of the glue outlet.

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