Double-color forming mold for double-end flared pipe and injection molding method

Abstract

The double-color forming mold comprises a female mold and a male mold, the female mold comprises a movable mold and a fixed mold, the male mold comprises a left male mold set and a right male mold set, and a first glue injection opening communicating with a first cavity and a second glue injection opening communicating with a second cavity are formed in the movable mold; anti-blocking is conducted on the second glue injection opening through the anti-blocking rod, the second glue injection opening and the second cavity are still kept to be communicated after glue injection is conducted on the first cavity, injection molding is conducted on the outer layer of the double-end flared pipe firstly, then injection molding is conducted on the inner layer, all water openings can be kept to be located outside the double-end flared pipe, and the influence of the water openings obtained after injection molding of the inner layer on injection molding of the inner layer is eliminated; and the technical problem that a water gap after inner layer injection molding is difficult to clean is solved.

Description

Technical Field

[0001] This invention belongs to the field of plastic molding or joining technology, specifically relating to a two-color molding die and injection molding method for a double-ended flared tube. Background Technology

[0002] Currently, common two-color injection molds that use an outer layer followed by an inner layer typically place the injection port on the punch or core mold, as disclosed in Chinese Invention Patent CN 108721737 A, "An Injector Piston and Its Manufacturing Method and Apparatus." This structure allows for cooling of the outer layer through water channels within the cavity mold. However, if the inner layer is still cooled by relying on the cavity mold, the cooling effect will be reduced due to obstruction by the outer layer, resulting in a decrease in cooling speed and reduced injection molding efficiency. Furthermore, during outer layer injection, the glue residue left on the inner wall of the outer layer solidifies, forming burrs or protrusions (commonly referred to as "gates"), affecting inner layer injection. During inner layer injection, the glue residue left on the inner wall of the inner layer also requires secondary processing for removal after solidification. The difficulty in removing burrs or protrusions on the inner wall is increased due to the narrow operating space. Therefore, it is necessary to improve the injection structure of two-color injection molds using an outer layer followed by an inner layer to overcome these technical problems. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a two-color molding mold for a double-ended flared pipe, which solves the technical problems of the outer layer gate affecting the inner layer injection and the inconvenience of cleaning the inner layer gate when the outer layer is injected first and the inner layer is injected later.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a two-color molding die for a double-ended flared tube, including a concave die and a convex die. The concave die includes a movable die and a fixed die that are directly opposite each other. The movable die is located directly above the fixed die. Half of the concave die cavity is provided on the facing surfaces of the fixed die and the movable die. When the movable die and the fixed die are aligned, a complete double-ended flared concave die cavity is formed. The convex die includes a left convex die group and a right convex die group, which are respectively disposed on the left and right sides of the concave die and are directly opposite the flared ends of the concave die cavity. The left convex die group includes a first left convex die and a second left convex die. The right convex die group includes a first right convex die and a second right convex die. The first left convex die and the first right convex die are simultaneously inserted into the concave die cavity to form a first cavity. The first cavity is used for injection molding the outer layer of the double-ended flared tube. The second left convex die and the second right convex die are simultaneously inserted between the concave die cavity and the inner wall of the outer layer of the double-ended flared tube to form a second cavity. The second cavity is used for injection molding the inner layer of the double-ended flared tube. The fixed mold is fixedly installed, while the movable mold is movably connected to a bracket and is driven by the main driver to rise and fall to achieve mold closing and mold opening; The left and right punch groups are driven by the auxiliary driver to perform mold closing and mold opening, and are driven by the conversion driver to switch between the first left punch and the second left punch, the first right punch and the second right punch; The movable mold has a first injection port communicating with the first cavity and a second injection port communicating with the second cavity. An anti-blocking rod that can be inserted into the second injection port is provided above the movable mold. When the anti-blocking rod is inserted into the second injection port, its lower end is in contact with the surface of the second left punch or the second right punch. An anti-blocking driver that drives the anti-blocking rod to rise and fall is connected to the bracket.

[0005] As a preferred embodiment, the left punch assembly further includes a central shaft. The first left punch and the second left punch are arranged circumferentially at a 90° angle and are vertically connected to the outer wall of the central shaft. The central shaft is perpendicular to the axial direction of the die cavity. Both ends of the central shaft are rotatably connected to the bearing seat through bearings. The conversion driver is a motor. The conversion driver is connected to one end of the central shaft to drive the central shaft to perform a 90° reciprocating swing motion. The bearings at both ends of the central shaft are slidably connected to two guide rails via sliding pairs. The extension direction of the guide rails is parallel to the axial direction of the die cavity. The auxiliary driver is a linear motor or a piston cylinder. The auxiliary driver drives the bearings at both ends of the central shaft to slide synchronously. The right convex module and the left convex module have mirror-symmetric structures, the same driving structure, and opposite driving directions.

[0006] As a preferred embodiment, a main cooling water channel is provided axially on any central shaft. Cooling branches connected to the main cooling water channel are respectively provided inside the second left punch and the second right punch. The main cooling water channel forms an inlet and an outlet at one end of the central shaft to connect the inlet pipe and the return pipe.

[0007] As a preferred embodiment, the first left punch and the first right punch are also provided with cooling branch lines that are connected to the main cooling water channel. The movable mold and the fixed mold may have an outer cooling water channel inside, which is used to cool the outer layer of the double-ended flared pipe.

[0008] As a preferred embodiment, the anti-clogging actuator is a piston cylinder or an electric push rod. The anti-clogging actuator is rotatably connected to the bracket. A large gear is fixedly connected to the housing of the anti-clogging actuator. An adjusting motor is connected to the bracket on one side of the anti-clogging actuator. A small gear meshing with the large gear is connected to the output shaft of the adjusting motor. The adjusting motor drives the anti-clogging actuator to reciprocate within a certain angle range through gear transmission. The anti-clogging actuator is offset to one side of the second injection port. The anti-clogging rod is Z-shaped. One end of the anti-clogging rod is connected to the output shaft of the anti-clogging actuator, and the other end swings with the rotation of the anti-clogging actuator. One end of the arc path of the swing is directly opposite the second injection port.

[0009] As a preferred embodiment, the outer diameter of the anti-blocking rod is smaller than the inner diameter of the second injection port, and an annular vent is formed between the anti-blocking rod and the second injection port; the upper surface of the second left punch and / or the second right punch is provided with a vent that communicates with the upper edge of the end of the second cavity.

[0010] As a preferred embodiment, both the outer circumferential surfaces of the first left punch and the first right punch are provided with recessed textures, the depth of which is sufficient to ensure that the inner wall of the outer layer completely detaches from the first left punch and the first right punch when the outer layer shrinks.

[0011] As a preferred embodiment, the first left punch and the first right punch are respectively provided with male and female heads that cooperate with each other at their facing ends. When the first left punch and the first right punch are inserted into the die cavity at the same time, they are positioned by the male and female heads, and the annular end faces of the male and female heads fit tightly together. The mating structure of the second left punch and the second right punch is the same as that of the first left punch and the first right punch.

[0012] The technical problem to be further solved by the present invention is to provide a two-color injection molding method for a double-ended flared tube, which solves the technical problems of the outer layer gate affecting the inner layer injection and the inconvenience of cleaning the inner layer gate when the outer layer is injected first and the inner layer is injected later.

[0013] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an injection molding method for a double-ended flared tube, using the above-mentioned two-color molding mold, and performing injection molding through the following specific steps: a. First, the fixed mold and the movable mold are closed together. Then, the first left punch and the first right punch are closed together to form the first cavity. The anti-blocking rod is inserted into the second injection port and abuts against the first left punch or the first right punch. Glue is injected into the first cavity through the first injection port. Then, the first cavity is cooled to form the outer layer of the double-headed flared tube. b. Pull out the first left punch and the first right punch, remove the anti-blocking rod, switch the second left punch and the second right punch and insert them into the die cavity. The second left punch, the second right punch and the outer layer form the second cavity. Glue is injected into the second cavity through the second injection port, and then the second cavity is cooled to form the inner layer of the double-headed flared tube. c. Pull out the second left punch and the second right punch, lift the movable die so that the anti-blocking rod is passively inserted into the second injection port and pushes the double-headed flaring tube away from the movable die and falls off. d. Remove the double-ended flared tube and repeat steps a to c.

[0014] As a preferred embodiment, in step b, after the anti-blocking rod is withdrawn, it is controlled to rotate at a certain angle so that the lower end of the anti-blocking rod deviates from the second injection port, thus freeing up injection space; in step c, the anti-blocking rod is controlled to reset, which is used to push the double-headed flared tube to achieve automatic demolding.

[0015] The beneficial effects of this invention are as follows: By opening a first injection port communicating with the first cavity and a second injection port communicating with the second cavity on the movable mold, and using an anti-blocking rod to prevent blockage of the second injection port, the second injection port remains connected to the second cavity even after the first cavity is filled with glue. This ensures that all sprues are located outside the double-ended flared tube even after the outer layer of the double-ended flared tube is injected first and then the inner layer is injected. This eliminates the influence of sprues after the inner layer injection on the inner layer injection and also eliminates the technical problem of the difficulty in removing sprues after the inner layer injection. Simultaneously, the anti-blocking rod can also be used as an ejector rod during demolding, simplifying the mold structure. Attached Figure Description

[0016] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the structure of the two-color molding die described in this invention; Figure 2 This is a schematic diagram of the central shaft end connection structure described in this invention; Figure 3 yes Figure 1 Enlarged view of part A in the image; Figure 4 This is a schematic diagram of the swing range of the anti-blocking rod described in this invention; Figure 5 This is a three-dimensional structural schematic diagram of the second left punch of the present invention; Figure 6 This is a three-dimensional structural schematic diagram of the first left punch of the present invention; Figure 7 This is a state diagram of the inner layer during injection molding of the two-color molding die described in this invention; Figures 1-7 In the middle section: 1. Movable mold; 2. Fixed mold; 3. Cavity; 4. Left punch assembly; 401. First left punch; 402. Second left punch; 5. Right punch assembly; 501. First right punch; 502. Second right punch; 6. First cavity; 7. Second cavity; 8. Support; 9. Main driver; 10. Auxiliary driver; 11. Conversion driver; 12. First injection port; 13. Second injection port; 14. Exhaust port; 15. Anti-blocking rod; 16. Anti-blocking driver; 17. Central shaft; 18. Shaft seat; 19. Main cooling water channel; 20. Cooling branch channel; 21. Inlet; 22. Outlet; 23. Outer cooling water channel; 24. Large gear; 25. Adjusting motor; 26. Small gear; 27. Texture; 28. Male end; 29. ​​Female end; 30. Annular end face; 31. Outer layer; 32. Inner layer; Guide rail. Detailed Implementation

[0017] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0018] like Figures 1-7The illustrated two-color molding die for a double-ended flared tube includes a concave die and a convex die. The concave die includes a movable die 1 and a fixed die 2 facing each other vertically. The movable die 1 is located directly above the fixed die 2. Half of the concave die cavity is provided on the facing surfaces of the fixed die 2 and the movable die 1. When the movable die 1 and the fixed die 2 are engaged, a complete double-ended flared concave die cavity 3 is formed. The convex die includes a left convex die group 4 and a right convex die group 5, respectively located on the left and right sides of the concave die and facing the flared ends of the concave die cavity 3. The left convex die group 4... The assembly includes a first left punch 401 and a second left punch 402. The right punch assembly 5 includes a first right punch 501 and a second right punch 502. The first left punch 401 and the first right punch 501 are simultaneously inserted into the cavity 3 to form a first cavity 6. The first cavity 6 is used for injection molding the outer layer of the double-ended flared tube. The second left punch 402 and the second right punch 502 are simultaneously inserted into the cavity 3 between the cavity 3 and the inner wall of the outer layer of the double-ended flared tube to form a second cavity 7. The second cavity 7 is used for injection molding the inner layer of the double-ended flared tube.

[0019] The double-ended flared tube of this invention has a double-layer structure, with an outer hard rubber layer and an inner soft rubber layer.

[0020] The fixed mold 2 is fixedly installed, and the movable mold 1 is movably connected to a bracket 8 and is driven by the main driver 9 to rise and fall to achieve mold closing and mold opening.

[0021] The left punch group 4 and the right punch group 5 are driven by the auxiliary driver 10 to perform mold closing and mold opening, and are driven by the conversion driver 11 to switch between the first left punch 401 and the second left punch 402, the first right punch 501 and the second right punch 502.

[0022] The movable mold 1 has a first injection port 12 communicating with the first cavity 6 and a second injection port 13 communicating with the second cavity 7. An anti-blocking rod 15 is provided above the movable mold 1, which can be inserted into the second injection port 13. When the anti-blocking rod 15 is inserted into the second injection port 13, its lower end is in contact with the surface of the second left punch 402 or the second right punch 502. An anti-blocking driver 16 for driving the anti-blocking rod 15 to rise and fall is connected to the bracket 8.

[0023] To demonstrate the internal structure of the cavity 3, Figure 1 The first left punch 401 is pulled out of the cavity 3. In actual injection molding, the first left punch 401 and the first right punch 501 are inserted into the cavity 3 together, similar to... Figure 7 The state shown.

[0024] The left punch assembly 4 also includes a central shaft 17. The first left punch 401 and the second left punch 402 are arranged circumferentially at a 90° angle and vertically connected to the outer wall of the central shaft 17. The central shaft 17 is perpendicular to the axial direction of the die cavity 3. Both ends of the central shaft 17 are rotatably connected to the bearing 18. The conversion driver 11 is a motor, which is connected to one end of the central shaft 17 to drive the central shaft 17 to perform a 90° reciprocating swing motion. To ensure accurate swing angle, a servo motor or a stepper motor can be used as the conversion driver 11, or a limit device can be set to limit the reciprocating swing of the central shaft 17 within a 90° range. The setting of the limit device is a conventional technical means and will not be described here.

[0025] Combination Figure 2 The bearing seats 18 at both ends of the central shaft 17 are slidably connected to two guide rails 33 via sliding pairs. The extension direction of the guide rails 33 is parallel to the axial direction of the die cavity 3. The auxiliary driver 10 is a linear motor or a piston cylinder, and the auxiliary driver 10 drives the bearing seats 18 at both ends of the central shaft 17 to slide synchronously. In this embodiment, the structures of the right punch group 5 and the left punch group 4 are mirror symmetrical, with the same driving structure and opposite driving directions. The left punch group 4 and the right punch group 5 are each equipped with two auxiliary drivers 10, and each bearing seat 18 is connected to one auxiliary driver 10 in a one-to-one correspondence. The four auxiliary drivers 10 are controlled by the same controller to perform synchronous actions.

[0026] In practical applications, there are many ways to drive the central shaft 17 to move. For example, electric actuators driven by servo motors can be used to drive the bearing seats 18 at both ends of the central shaft 17, utilizing the high-precision controllability of the servo motor's rotation angle to achieve synchronous movement at both ends of the central shaft 17. Alternatively, a lead screw and nut mechanism can be used to drive the two bearing seats 18 to move separately, while bevel gears and a transmission shaft keep the two lead screws synchronized. A single motor can be used to drive the two lead screws to rotate synchronously, thereby driving the bearing seats 18 at both ends of the central shaft 17 to move synchronously.

[0027] In this embodiment, a main cooling water passage 19 is axially formed on any central shaft 17. Cooling branch passages 20, communicating with the main cooling water passage 19, are respectively provided inside the second left punch 402 and the second right punch 502. The main cooling water passage 19 forms an inlet 21 and an outlet 22 at one end of the central shaft 17 for connecting the inlet pipe and the return pipe. Cooling water enters the main cooling water passage 19 through the inlet 21, and then enters the cooling branch passages 20. The cooling branch passages 20 cool the second left punch 402 and the second right punch 502, cooling the inner layer of the double-ended flared pipe. The cooling water then returns to the main cooling water passage 19 and flows out for recycling. The main cooling water passage 19 is actually composed of two parallel, elongated holes. Each cooling branch passage 20 is a continuous, meandering channel. The two ends of each cooling branch passage 20 are connected to the two elongated holes of the main cooling water passage 19, thus achieving water cooling of the second left punch 402 and the second right punch 502.

[0028] Cooling of the outer layer of the double-ended flared tube can be achieved by providing cooling branch lines 20 connected to the main cooling water channel 19 inside the first left punch 401 and the first right punch 501, or by providing an outer cooling water channel 23 inside the movable mold 1 and the fixed mold 2. Figure 1 Although the diagram shows that cooling branches 20 are provided inside the first left punch 401 and the first right punch 501, and outer cooling water channels 23 are provided inside both the movable mold 1 and the fixed mold 2, in actual applications, only one of the two can be selected.

[0029] The specific layout of the outer cooling water channel 23 can be adjusted according to cooling needs. Water cooling is a conventional technical means of mold cooling, so the specific cooling water channel and its connection to the water source will not be described in this embodiment.

[0030] Combination Figure 1 , Figure 3 and Figure 4 As shown, the anti-blocking actuator 16 is a piston cylinder or an electric push rod. The anti-blocking actuator 16 is rotatably connected to the bracket 8. A large gear 24 is fixedly connected to the outer shell of the anti-blocking actuator 16. An adjusting motor 25 is connected to the bracket 8 on one side of the anti-blocking actuator 16. A small gear 26 that meshes with the large gear 24 is connected to the output shaft of the adjusting motor 25. The adjusting motor 25 drives the anti-blocking actuator 16 to reciprocate within a certain angle range, such as 90°, through gear transmission. The anti-blocking actuator 16 is offset to one side of the second glue injection port 13. The anti-blocking rod 15 has a Z-shaped structure. The adjacent bends of the anti-blocking rod 15 are perpendicular to each other. One end of the anti-blocking rod 15 is connected to the output shaft of the anti-blocking actuator 16, and the other end swings with the rotation of the anti-blocking actuator 16. One end of the swinging arc path is directly opposite the second glue injection port 13. Adjusting the motor 25 drives the anti-blocking driver 16 to rotate, causing the lower end of the anti-blocking rod 15 to rotate away from the second glue injection port 13, which can free up glue injection space for the glue injection head to be inserted into the second glue injection port 13 for glue injection.

[0031] like Figure 5 As shown, in this embodiment, the outer diameter of the anti-blocking rod 15 is preferably set to be smaller than the inner diameter of the second injection port 13, so that an annular vent 14 can be formed between the anti-blocking rod 15 and the second injection port 13, thus omitting the vent 14 that is connected to the first injection port 12. Correspondingly, the position of the second injection port 13 is set at the upper edge of the second cavity 7. The upper surface of the second left punch 402 is provided with a vent 14 that is connected to the upper edge of the end of the second cavity 7. In practical applications, the vent 14 that is connected to the second cavity 7 can be set in other parts as needed, such as the upper surface of the second right punch 502.

[0032] like Figure 6As shown, in this embodiment, recessed textures 27 are also provided on the outer circumferential surfaces of the first left punch 401 and the first right punch 501. The depth of the textures 27 is sufficient to ensure that the inner wall of the outer layer completely detaches from the first left punch 401 and the first right punch 501 when the outer layer shrinks due to cold. The textures 27 also form raised textures on the inner wall of the outer layer. During the injection molding of the inner layer, the inner layer and the inner wall of the outer layer are strengthened by the raised textures, making the bond between the inner layer and the outer layer more secure.

[0033] The first left punch 401 and the first right punch 501 are respectively provided with male heads 28 and female openings 29 that cooperate with each other at their opposite ends. When the first left punch 401 and the first right punch 501 are simultaneously inserted into the die cavity 3, they are positioned by the male heads 28 and female openings 29 to improve their concentricity. The annular end faces 30 of the male heads 28 and female openings 29 are tightly fitted together. The mating structure of the second left punch 402 and the second right punch 502 is the same as that of the first left punch 401 and the first right punch 501.

[0034] The working process of this invention is a method for injection molding a double-ended flared tube: using the above-mentioned two-color molding die, injection molding is performed through the following specific steps: a. First, the fixed mold 2 and the movable mold 1 are closed. Then, the first left punch 401 and the first right punch 501 are closed to form the first cavity 6. The anti-blocking rod 15 is inserted into the second injection port 13 and abuts against the first left punch 401 or the first right punch 501. Glue is injected into the first cavity 6 through the first injection port 12. Then, the first cavity 6 is cooled to form the outer layer 31 of the double-ended flared tube. Figure 1 As shown in the right half.

[0035] b. Pull out the first left punch 401 and the first right punch 501, remove the anti-blocking rod 15, and switch to insert the second left punch 402 and the second right punch 502 into the die cavity 3. The second left punch 402, the second right punch 502, and the outer layer 31 constitute the second cavity 7. Glue is injected into the second cavity 7 through the second injection port 13, and then the second cavity 7 is cooled to form the inner layer 32 of the double-ended flared tube. Figure 7 As shown.

[0036] c. Pull out the second left punch 402 and the second right punch 502, lift the movable mold 1 so that the anti-blocking rod 15 is passively inserted into the second injection port 13 and pushes the double-headed flared tube to disengage from the movable mold 1 and fall off.

[0037] d. Remove the double-ended flared tube and repeat steps a to c.

[0038] When performing step b, after the anti-blocking rod 15 is withdrawn, the anti-blocking rod 15 is rotated at a certain angle so that the lower end of the anti-blocking rod 15 is deviated from the second injection port 13, making room for injection. When performing step c, the anti-blocking rod 15 is reset and used to push the double-ended flared tube to achieve automatic demolding.

[0039] When implementing step a, the outer cooling water channel 23 is used to cool the outer layer 31. During cooling, the outer layer 31 gradually cools from the outer wall to the inner wall. When the inner wall temperature cools down to the demolding temperature, the first left punch 401 and the first right punch 501 immediately disengage and are inserted into the second left punch 402 and the second right punch 502 to inject glue into the second cavity 7. During the injection of glue, since the inner wall of the outer layer still has a certain temperature, it will melt after contacting the inner layer glue due to the temperature of the inner layer glue, so that the outer layer 31 and the inner layer 32 form a fusion effect on the bonding surface, thereby improving the bonding force between the outer layer 31 and the inner layer 32.

[0040] The above embodiments are merely illustrative of the principles and effects of the present invention, as well as some examples of its application, and are not intended to limit the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention.

Claims

1. A two-color molding die for a double-ended flared tube, comprising a concave die and a convex die, characterized in that, The die includes a movable die (1) and a fixed die (2) facing each other vertically. The movable die (1) is located directly above the fixed die (2). Half of the die cavity is provided on the facing surfaces of the fixed die (2) and the movable die (1). When the movable die (1) and the fixed die (2) are engaged, a complete double-headed flared die cavity (3) is formed. The punch includes a left punch group (4) and a right punch group (5) respectively located on the left and right sides of the die and facing the flared ends of the die cavity (3). The left punch group (4) includes a first left punch (401) and a second left punch (401). The left punch (402) and the right punch group (5) include a first right punch (501) and a second right punch (502). The first left punch (401) and the first right punch (501) are simultaneously inserted into the cavity (3) to form a first cavity (6). The first cavity (6) is used to inject the outer layer of the double-ended flared tube. The second left punch (402) and the second right punch (502) are simultaneously inserted into the cavity (3) and the inner wall of the outer layer of the double-ended flared tube to form a second cavity (7). The second cavity (7) is used to inject the inner layer of the double-ended flared tube. The fixed mold (2) is fixedly set, and the movable mold (1) is movably connected to a bracket (8) and driven by the main driver (9) to rise and fall to realize mold closing and mold opening; The left punch group (4) and the right punch group (5) are driven by the auxiliary driver (10) to perform mold closing and mold opening, and are driven by the conversion driver (11) to switch between the first left punch (401) and the second left punch (402), the first right punch (501) and the second right punch (502). The movable mold (1) is provided with a first injection port (12) communicating with the first cavity (6) and a second injection port (13) communicating with the second cavity (7). An anti-blocking rod (15) that can be inserted into the second injection port (13) is provided above the movable mold (1). When the anti-blocking rod (15) is inserted into the second injection port (13), its lower end is in contact with the surface of the second left punch (402) or the second right punch (502). An anti-blocking driver (16) that drives the anti-blocking rod (15) to rise and fall is connected to the bracket (8).

2. The two-color molding die according to claim 1, characterized in that, The left punch assembly (4) also includes a central shaft (17). The first left punch (401) and the second left punch (402) are arranged circumferentially at a 90° angle and vertically connected to the outer wall of the central shaft (17). The central shaft (17) is perpendicular to the axial direction of the die cavity (3). The two ends of the central shaft (17) are rotatably connected to the bearing seat (18) through bearings. The conversion driver (11) is a motor. The conversion driver (11) is connected to one end of the central shaft (17) and drives the central shaft (17) to perform a 90° reciprocating swing action. The bearing seats (18) at both ends of the central shaft (17) are slidably connected to two guide rails (33) through sliding pairs. The extension direction of the guide rails (33) is parallel to the axial direction of the die cavity (3). The auxiliary driver (10) is a linear motor or a piston cylinder. The auxiliary driver (10) drives the bearing seats (18) at both ends of the central shaft (17) to slide synchronously. The right convex module (5) and the left convex module (4) are mirror symmetrical in structure, have the same driving structure, and drive in opposite directions.

3. The two-color molding die according to claim 2, characterized in that, A main cooling water passage (19) is provided axially on any central shaft (17). Cooling branch passages (20) connected to the main cooling water passage (19) are respectively provided inside the second left punch (402) and the second right punch (502). The main cooling water passage (19) forms an inlet (21) and an outlet (22) at one end of the central shaft (17) to connect the inlet pipe and the return pipe.

4. The two-color molding die according to claim 3, characterized in that, The first left punch (401) and the first right punch (501) are also provided with cooling branch lines (20) that are connected to the main cooling water channel (19). The movable mold (1) and the fixed mold (2) are provided with an outer cooling water channel (23) for cooling the outer layer of the double-ended flared pipe.

5. The two-color molding die according to claim 1, characterized in that, The anti-blocking actuator (16) is a piston cylinder or an electric push rod. The anti-blocking actuator (16) is rotatably connected to the bracket (8). A large gear (24) is fixedly connected to the outer shell of the anti-blocking actuator (16). An adjusting motor (25) is connected to the bracket (8) on one side of the anti-blocking actuator (16). A small gear (26) that meshes with the large gear (24) is connected to the output shaft of the adjusting motor (25). The adjusting motor (25) drives the anti-blocking actuator (16) to reciprocate within a certain angle range through gear transmission. The anti-blocking actuator (16) is biased to one side of the second glue injection port (13). The anti-blocking rod (15) is Z-shaped. One end of the anti-blocking rod (15) is connected to the output shaft of the anti-blocking actuator (16), and the other end swings with the rotation of the anti-blocking actuator (16). One end of the swinging arc path is directly opposite the second glue injection port (13).

6. The two-color molding die according to claim 1, characterized in that, The outer diameter of the anti-blocking rod (15) is smaller than the inner diameter of the second injection port (13), and an annular vent (14) is formed between the anti-blocking rod (15) and the second injection port (13); the upper surface of the second left punch (402) and / or the second right punch (502) is provided with a vent (14) that communicates with the upper edge of the end of the second cavity (7).

7. The two-color molding die according to claim 1, characterized in that, The outer circumferential surfaces of the first left punch (401) and the first right punch (501) are provided with recessed textures (27), and the depth of the textures (27) is sufficient to completely separate the inner wall of the outer layer from the first left punch (401) and the first right punch (501) when the outer layer shrinks.

8. The two-color molding die according to claim 2, characterized in that, The first left punch (401) and the first right punch (501) are respectively provided with male heads (28) and female mouths (29) that cooperate with each other at their opposite ends. When the first left punch (401) and the first right punch (501) are inserted into the die cavity (3) at the same time, they are positioned by the male head (28) and the female mouth (29), and the annular end faces (30) of the male head (28) and the female mouth (29) are tightly fitted. The mating structure of the second left punch (402) and the second right punch (502) is the same as that of the first left punch (401) and the first right punch (501).

9. A method for injection molding a double-ended flared tube, characterized in that, Using any one of the two-color molding dies described in claims 1 to 8, injection molding is performed through the following specific steps: a. First, the fixed mold (2) and the movable mold (1) are closed together. Then, the first left punch (401) and the first right punch (501) are closed together to form the first cavity (6). The anti-blocking rod (15) is inserted into the second injection port (13) and abuts against the first left punch (401) or the first right punch (501). Glue is injected into the first cavity (6) through the first injection port (12). Then the first cavity (6) is cooled to form the outer layer (31) of the double-headed flared tube. b. Pull out the first left punch (401) and the first right punch (501), remove the anti-blocking rod (15), switch the second left punch (402) and the second right punch (502) into the cavity (3), the second left punch (402), the second right punch (502) and the outer layer (31) form the second cavity (7), inject glue into the second cavity (7) through the second glue injection port (13), and then cool the second cavity (7) to form the inner layer (32) of the double-headed flared tube. c. Pull out the second left punch (402) and the second right punch (502), lift the movable mold (1) so that the anti-blocking rod (15) is passively inserted into the second injection port (13) and pushes the double-headed flared tube to disengage from the movable mold (1) and fall off; d. Remove the double-ended flared tube and repeat steps a to c.

10. The injection molding method according to claim 9, characterized in that, When implementing step b, after the anti-blocking rod (15) is withdrawn, the anti-blocking rod (15) is rotated at a certain angle so that the lower end of the anti-blocking rod (15) is deviated from the second injection port (13) to make room for injection. When implementing step c, the anti-blocking rod (15) is reset to push the double-headed flared tube to achieve automatic demolding.

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