A tool and process for making R angle of inner cavity of curved pipe

Abstract

The present invention provides a tool and a process for making the R angle of the inner cavity of a bent pipe, and relates to the technical field of bending equipment. The invention solves the technical problem that the R angle of the inner cavity of a bent pipe is difficult to form in the prior art. The invention comprises a rear module, a front module, a positioning pin, a guide pin and a plastic part. The plastic part is prefabricated in advance according to the requirements of different bent pipe design shapes, and the outer dimensions of the plastic part match the inner cavity dimensions of the injection blank to be formed. The plastic part can be placed in the injection blank molding cavity, and the two ends of the plastic part are fixed by the positioning pin and the guide pin. After the rear module and the front module are molded together, an injection blank is formed in the injection blank molding cavity. After the injection blank is formed, the plastic part is dissolved and removed with a solution to form the final product, and the R angle is generated. The manufacturing process is simpler and more effective, the overall automation of the manufacturing tool is high, and the manufacturing is very convenient.

Description

Technical Field

[0001] The invention relates to the technical field of pipe bending equipment, and in particular to a manufacturing tool and a manufacturing process for an R angle of an inner cavity of a pipe bending. Background Art

[0002] Bend pipes are common structural parts in the fields of chemical, petrochemical, aviation, etc. Since the inner cavity of the bend pipe is difficult to process, bend pipes with high dimensional accuracy requirements are mostly formed in a one-time process. When the existing equipment is used to make the R angle of the inner cavity of the bend pipe, the mold insert is straight and the R shape cannot be made. If the shape is made, the mold will not be able to escape from the product cavity during operation, which makes it difficult to form the R angle of the inner cavity of the bend pipe. Summary of the invention

[0003] The purpose of the present invention is to provide a tool and process for making the R angle of the inner cavity of a curved pipe, so as to solve the technical problem that the R angle of the inner cavity of a curved pipe is difficult to form in the prior art. The preferred technical solution among the many technical solutions provided by the present invention can produce many technical effects as described below.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A tool for making the R angle of the inner cavity of a curved pipe, comprising a rear module, a front module, a positioning pin, a guide pin and a plastic part, wherein the rear module comprises a rear mold core, the rear mold core is provided with a first rear molding groove, the front module comprises a front mold core, the front mold core is provided with a first front molding groove, after the rear mold core and the front mold core are pressed together, the first rear molding groove and the first front molding groove can enclose and form an injection blank molding cavity matching the external shape of the injection blank, the plastic part can be placed in the injection blank molding cavity, and the outer dimensions of the plastic part match the inner cavity dimensions of the injection blank;

[0006] The rear mold core is provided with two rear semicircular grooves connected with the first rear forming grooves, and the front mold core is provided with two front semicircular grooves connected with the first front forming grooves. When the rear mold core and the front mold core are pressed together, the two rear semicircular grooves and the two front semicircular grooves can enclose and form two tubular cavities for the positioning pin and the guide pin to slide.

[0007] The head ends of the positioning needle and the guide needle are both connected to a set of sliding structures and can move in the tubular cavity driven by the sliding structures. When the positioning needle and the guide needle move to the extreme position farthest from the plastic part in the tubular cavity, the needle ends can block the tubular cavity. When the positioning needle and the guide needle move to the extreme position closest to the plastic part in the tubular cavity, the needle ends can be detachably connected to one end of the plastic part.

[0008] The rear mold core is provided with a first flow channel, and two ends of the first flow channel are respectively connected with the injection molding cavity and the external feeding structure.

[0009] Preferably, the rear module further comprises a rear mold body, the rear mold core is embedded in the rear mold body and is detachably connected to the rear mold body, and the front module further comprises a front mold body, the front mold core is embedded in the front mold body and is detachably connected to the front mold body.

[0010] Preferably, the rear module also includes a rear template and a support plate, the number of the support plates is two, the rear mold body and the rear template are connected together through the two support plates, the rear module is connected to the external structure through the rear template, and the front module also includes a front template, the front template is connected to the front mold body, and the front module is connected to the external structure through the front template.

[0011] Preferably, the sliding structure includes a slider assembly and a clamping strip, and the number of the clamping strips is two. A slideway for the slider assembly to slide is provided on the rear mold core, and its displacement in the depth direction of the slideway is limited by the two clamping strips. The head end of the positioning pin and the head end of the guide pin are both connected to a group of slider assemblies. The slider assembly is connected to an external structure and moves under the drive of the external structure to drive the positioning pin and the guide pin to move.

[0012] Preferably, the rear module further includes an ejector structure, which includes an ejector plate and a plurality of first ejectors, the first post-molding groove is provided with a first through hole at a corresponding position of each of the first ejectors, the head end of the first ejector is connected to the ejector plate, the needle end of the first ejector is penetrated through the first through hole and blocks the first through hole, and an external force pushes the ejector plate forward to move the ejector plate toward the rear mold core so that the needle end of the first ejector penetrates through the first through hole into the injection molding cavity and ejects the object in the injection molding cavity.

[0013] Preferably, it also includes a plastic part molding structure, which includes a plastic part rear mold and a plastic part front mold, the plastic part rear mold and the plastic part front mold are respectively and correspondingly embedded in the rear mold core and the front mold core, the plastic part rear mold is provided with a second rear molding groove, and the plastic part front mold is provided with a second front molding groove, the second rear molding groove and the second front molding groove can form a plastic part molding cavity matching the shape of the plastic part after being enclosed, the rear mold core is provided with a second flow channel, and the two ends of the second flow channel are respectively connected to the plastic part molding cavity and the external feeding structure.

[0014] Preferably, the plastic part molding structure further includes a plurality of second ejector pins, the second post-molding groove is provided with a second through hole at a corresponding position of each second ejector pin, the needle end of the second ejector pin is penetrated through the second through hole and blocks the second through hole, and external force pushes the plurality of second ejector pins forward to enable the needle end of the second ejector pin to penetrate through the second through hole into the plastic part molding cavity and eject the object in the plastic part molding cavity.

[0015] Preferably, a cross-shaped groove is formed at the needle end of the positioning pin, and a cross-shaped end matched with the cross-shaped groove is provided at one end of the plastic part connected to the positioning pin.

[0016] Preferably, a cylindrical groove is formed at the needle end of the guide pin, and a cylindrical end matched with the cylindrical groove is provided at one end of the plastic part connected to the guide pin.

[0017] A process for manufacturing the R angle of the inner cavity of a curved pipe comprises the following specific steps:

[0018] Step a. injecting a plastic part through a plastic part molding structure;

[0019] Step b. placing the plastic part obtained in step a in the injection molding cavity, connecting one end of the plastic part to the needle end of the positioning needle for positioning;

[0020] Step c. Pushing the guide pin to the other end of the plastic part so that the plastic part is connected to the needle end of the guide pin;

[0021] Step d. Close the rear module and the front module, inject the metal material, and after cooling, open the mold to take out the injection blank with the plastic part;

[0022] Step e. Soak the injection molded product in the solution, and the solution and the plastic part undergo a chemical reaction to remove the plastic part. The inner cavity of the injection molded product forms a cavity that is the same as the outer shape of the plastic part, and an R angle is generated.

[0023] The present invention mentions a tool and process for making the R angle of the inner cavity of a bent pipe. Plastic parts are prefabricated in advance according to the requirements of different bent pipe design shapes, and the outer dimensions of the plastic parts match the inner cavity dimensions of the injection blank to be molded. The plastic parts can be placed in the injection blank molding cavity, and the two ends of the plastic parts are fixed by positioning pins and guide pins. After the rear module and the front module are molded together, an injection blank is formed in the injection blank molding cavity. After the injection blank is molded, the plastic parts are dissolved and removed with a solution to form the final product, generating an R angle. The manufacturing process is simpler and more effective, the overall degree of automation of the manufacturing tool is high, and the manufacturing is very convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is a detailed view of the rear mold core (without showing the injection blank) in an embodiment of the present invention;

[0026] Figure 2 is a structural diagram of the rear mold core in an embodiment of the present invention;

[0027] Figure 3 is a structural diagram of the front mold core and the front mold body in an embodiment of the present invention;

[0028] Figure 4 is a structural diagram of a rear module (showing an injection molded product and a sliding structure) in an embodiment of the present invention;

[0029] Figure 5 is a combined structural diagram of a first ejector pin, a second ejector pin and a rear module in an embodiment of the present invention;

[0030] Figure 6 is a structural diagram of a rear module and a front module when pressed together in an embodiment of the present invention;

[0031] In the figure, 1 is a rear module; 11 is a rear mold core; 111 is a first rear molding groove; 112 is a rear semicircular groove; 113 is a first flow channel; 114 is a second flow channel; 12 is a rear mold body; 13 is a rear mold plate; 14 is a support plate; 15 is an ejector structure; 151 is an ejector plate; 152 is a first ejector; 153 is a first through hole;

[0032] 2. front module; 21. front mold core; 211. first front molding groove; 212. front semicircular groove; 22. front mold body; 23. front mold plate;

[0033] 3. Positioning needle;

[0034] 4. Guide pin;

[0035] 5. Plastic parts;

[0036] 6. Injection blank;

[0037] 7. Sliding structure; 71. Sliding block assembly; 72. Pressing strip;

[0038] 8. Plastic part molding structure; 81. Plastic part rear mold; 811. Second rear molding groove; 812. Second through hole; 82. Plastic part front mold; 821. Second front molding groove; 83. Second ejector pin. DETAILED DESCRIPTION

[0039] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0040] In the description of the present invention, it should be understood that the terms "center", "lateral", "length", "width", "height", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "side" and the like indicate positions or positional relationships based on the attached Figure 1 The orientation or positional relationship shown is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0041] Reference Figures 1 to 6The present invention provides a tool for making the R angle of the inner cavity of a curved pipe, comprising a rear module 1, a front module 2, a positioning pin 3, a guide pin 4 and a plastic part 5, wherein the rear module 1 comprises a rear mold core 11, on which a first rear molding groove 111 is provided, and the front module 2 comprises a front mold core 21, on which a first front molding groove 211 is provided, and the rear module 1 and the front module 2 can move toward each other under the drive of an external structure and finally be pressed together, so that the rear mold core 11 and the front mold core 21 are pressed together, and the first rear mold core 11 is pressed together. The molding groove 111 and the first front molding groove 211 can enclose and form an injection blank molding cavity that matches the external shape of the injection blank 6. The outer dimensions of the plastic part 5 match the inner cavity dimensions of the injection blank 6 to be molded. The corresponding plastic part 5 can be manufactured in advance according to different shape requirements. The plastic part 5 can be placed in the injection blank molding cavity. The plastic part 5 can preferably be made of a material that can react chemically with a dissolving solution, so that after the injection blank 6 is molded, the plastic part 5 can be dissolved and removed using a solution to form a final product.

[0042] The rear mold core 11 is provided with two rear semicircular grooves 112 connected with the first rear molding grooves 111, and the front mold core 21 is provided with two front semicircular grooves 212 connected with the first front molding grooves 211. After the rear mold core 11 and the front mold core 21 are pressed together, the two rear semicircular grooves 112 and the two front semicircular grooves 212 can enclose and form two tubular cavities for the positioning pin 3 and the guide pin 4 to slide.

[0043] The head ends of the positioning needle 3 and the guide needle 4 are both connected to a set of sliding structures 7 and can move in the tubular cavity driven by the sliding structure 7. When the positioning needle 3 and the guide needle 4 move to the extreme position farthest from the plastic part 5 in the tubular cavity, the needle ends can block the tubular cavity. When the positioning needle 3 and the guide needle 4 move to the extreme position closest to the plastic part 5 in the tubular cavity, the needle ends can be detachably connected to one end of the plastic part 5. The two ends of the plastic part 5 are fixed by the positioning needle 3 and the guide needle 4, and then the injection molding process is performed;

[0044] A first flow channel 113 is provided on the rear mold core 11, and the two ends of the first flow channel 113 are respectively connected to the injection blank molding cavity and the external feeding structure. The external feeding structure can feed the injection material into the injection blank molding cavity through the first flow channel 113, and form an injection blank 6 after cooling. At this time, the positioning pin 3 and the guide pin 4 can be separated from the injection blank 6 to form a separate injection blank 6. The injection blank 6 is immersed in a solution to dissolve and remove the plastic part 5 to form a final product.

[0045] As an optional embodiment, the rear module 1 also includes a rear mold body 12, the rear mold core 11 is embedded in the rear mold body 12 and is detachably connected to the rear mold body 12, and the rear mold core 11 can be preferably embedded in the rear mold body 12 by opening a groove body and connected together by bolts. The front module 2 also includes a front mold body 22, the front mold core 21 is embedded in the front mold body 22 and is detachably connected to the front mold body 22, and the front mold core 21 can be preferably embedded in the front mold body 22 by opening a groove body and connected together by bolts. In this embodiment, the rear mold core 11 and the front mold core 21 are preferably used with high strength and The rear mold body 12 and the front mold body 22 are made of materials with higher hardness. In comparison, the rear mold body 12 and the front mold body 22 are made of materials with slightly lower strength than the rear mold core 11 and the front mold core 21. Because the rear mold body 12 and the front mold body 22 need to have more holes and larger grooves when they are produced, materials with lower strength are more conducive to their production. Because the rear mold core 11 and the front mold core 21 are the main force-bearing structures when the molds are closed, and the first rear molding groove 111 and the first front molding groove 211 are provided inside the two, the higher strength rear mold core 11 and the front mold core 21 can improve the design specifications and extend the service life.

[0046] As an optional embodiment, the rear module 1 also includes a rear template 13 and a support plate 14, the number of the support plates 14 is two, the rear mold body 12 and the rear template 13 are connected together by the two support plates 14, the rear module 1 is connected to the external structure through the rear template 13, the external structure connected to the rear template 13 can drive the rear module 1 to move toward the front module 2, the setting of the support plate 14 can provide space for the ejector structure 15 mentioned below, the front module 2 also includes a front template 23, the front template 23 is connected to the front mold body 22, the front module 2 is connected to the external structure through the front template 23, the external structure connected to the front template 23 can drive the front module 2 to move toward the rear module 1.

[0047] As an optional embodiment, the sliding structure 7 includes a slider assembly 71 and a clamping strip 72, and the number of the clamping strips 72 is two. A slideway for the slider assembly 71 to slide is opened on the rear mold core 11, and its displacement in the depth direction of the slideway is limited by two clamping strips 72. Therefore, the slider assembly 71 can only move along the length direction of the slideway. The head ends of the positioning pins 3 and the guide pins 4 are both connected to a group of slider assemblies 71. The slider assembly 71 is connected to the external structure and moves under the drive of the external structure to drive the positioning pins 3 and the guide pins 4 to move, so that the positioning pins 3 and the guide pins 4 are connected or disconnected from the two ends of the plastic part 5.

[0048] As an optional embodiment, the rear module 1 further includes an ejector pin structure 15, which includes an ejector pin plate 151 and a plurality of first ejector pins 152. The first rear molding groove 111 is provided with a first through hole 153 at a corresponding position of each first ejector pin 152. The first through hole 153 also simultaneously penetrates the rear mold core 11 and the rear mold body 12. The head end of the first ejector pin 152 is connected to the ejector pin plate 151, and the needle end of the first ejector pin 152 is penetrated at the first through hole 153 and seals the first through hole 153. The ejector plate 151 is pushed forward by an external force, so that the ejector plate 151 moves toward the rear mold core 11, so that the needle end of the first ejector 152 passes through the first through hole 153, enters the injection blank molding cavity, and ejects the object in the injection blank molding cavity, thereby solving the problem that it is inconvenient to directly take out the injection blank 6 in the injection blank molding cavity. Different first ejectors 152 are located at different positions of the injection blank 6 and ejected at the same time, protecting the structure of the injection blank 6 itself from damage.

[0049] As an optional embodiment, it also includes a plastic part molding structure 8, which can preform the plastic part 5, so that the production tool mentioned in this embodiment can not only produce the injection blank 6, but also preform the plastic part 5, one machine can be used for two purposes, saving space, improving work efficiency, and reducing costs. The plastic part molding structure 8 includes a plastic part rear mold 81 and a plastic part front mold 82, and the plastic part rear mold 81 and the plastic part front mold 82 are respectively embedded in the rear mold core 11 and the front mold core 21, and the plastic part rear mold 81 is provided with a second rear molding groove 811, and the plastic part front mold 82 is provided with a second rear molding groove 812. There is a second front molding groove 821, and the second rear molding groove 811 and the second front molding groove 821 can form a plastic part molding cavity matching the shape of the plastic part 5 after being enclosed. A second flow channel 114 is opened on the rear mold core 11, and the two ends of the second flow channel 114 are respectively connected to the plastic part molding cavity and the external feeding structure. The external feeding structure can feed the injection feed into the plastic part molding cavity through the second flow channel 114. The molding machine forms the plastic part 5 after heating. The external feeding structure can control the opening of the first flow channel 113 and the second flow channel 114, and open different flow channels when making different structures.

[0050] As an optional embodiment, the plastic part molding structure 8 further includes a plurality of second ejector pins 83. The second post-molding groove 811 is provided with a second through hole 812 at the corresponding position of each second ejector pin 83. The needle end of the second ejector pin 83 is penetrated through the second through hole 812 and blocks the second through hole 812. External force pushes the plurality of second ejector pins 83 forward to enable the needle end of the second ejector pin 83 to penetrate through the second through hole 812 and enter the plastic part molding cavity to eject the object in the plastic part molding cavity, thereby solving the problem that it is inconvenient to directly take out the plastic part 5 in the plastic part molding cavity. Different second ejector pins 83 are located at different positions of the plastic part 5 and are ejected at the same time, thereby protecting the structure of the plastic part 5 itself from damage.

[0051] As an optional implementation, a cross-shaped groove is provided at the needle end of the positioning pin 3, and a cross-shaped end cap matching the cross-shaped groove is provided at one end of the plastic part 5 connected to the positioning pin 3. The cross-shaped groove and the cross-shaped end cap cooperate with each other to resist the torsional force of the plastic part 5 and the positioning pin 3 during injection molding.

[0052] As an optional implementation, a cylindrical groove is formed at the needle end of the guide needle 4, and a cylindrical end matched with the cylindrical groove is provided at one end of the plastic part 5 connected to the guide needle 4.

[0053] As an optional implementation, the first flow channel 113 is an arc-shaped structure. The first flow channel 113 adopts an arc-shaped design to extend the length of the flow channel, which can control the flow rate and make feeding smoother.

[0054] The present invention also provides a process for manufacturing the R angle of the inner cavity of a curved pipe, comprising the following specific steps:

[0055] Step a. injecting a plastic part through a plastic part molding structure;

[0056] Step b. placing the plastic part obtained in step a in the injection molding cavity, and driving the positioning pin to move the sliding structure so that one end of the plastic part is connected to the needle end of the positioning pin for positioning;

[0057] Step c. The sliding structure drives the guide pin to move, and pushes the guide pin to the position of the other end of the plastic part, so that the plastic part is connected to the needle end of the guide pin. At this time, the two ends of the plastic part are fixed to the positioning pin and the guide pin respectively;

[0058] Step d. Close the rear module and the front module, and the external feed structure injects the metal material into the injection molding cavity through the first flow channel. After cooling, open the rear module and the front module, and take out the injection molding with the plastic part with the help of the ejector structure;

[0059] Step e. Soak the injection blank removed in step d in a solution. The solution and the plastic part undergo a chemical reaction to remove the plastic part, and finally the inner cavity of the injection blank forms a cavity with the same shape as the plastic part, and an R angle is generated.

[0060] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A tool for making the R angle of the inner cavity of a curved pipe, characterized in that: The invention comprises a rear module (1), a front module (2), a positioning pin (3), a guide pin (4) and a plastic part (5), wherein: the rear module (1) comprises a rear mold core (11), the rear mold core (11) is provided with a first rear molding groove (111), the front module (2) comprises a front mold core (21), the front mold core (21) is provided with a first front molding groove (211), after the rear mold core (11) and the front mold core (21) are pressed together, the first rear molding groove (111) and the first front molding groove (211) can enclose and form an injection mold cavity that matches the external shape of the injection mold (6), the plastic part (5) can be placed in the injection mold cavity, and the outer dimensions of the plastic part (5) match the inner dimensions of the injection mold (6); The rear mold core (11) is provided with two rear semicircular grooves (112) connected to the first rear molding grooves (111), and the front mold core (21) is provided with two front semicircular grooves (212) connected to the first front molding grooves (211). When the rear mold core (11) and the front mold core (21) are pressed together, the two rear semicircular grooves (112) and the two front semicircular grooves (212) can enclose and form two tubular cavities for the positioning pin (3) and the guide pin (4) to slide. The head ends of the positioning needle (3) and the guide needle (4) are both connected to a set of sliding structures (7) and can move in the tubular cavity under the drive of the sliding structure (7); when the positioning needle (3) and the guide needle (4) move to the extreme position farthest from the plastic part (5) in the tubular cavity, the needle ends can block the tubular cavity; when the positioning needle (3) and the guide needle (4) move to the extreme position closest to the plastic part (5) in the tubular cavity, the needle ends can be detachably connected to one end of the plastic part (5); The rear mold core (11) is provided with a first flow channel (113), and two ends of the first flow channel (113) are respectively connected to the injection molding cavity and the external feeding structure.

2. The tool for making the R angle of the inner cavity of a bent pipe according to claim 1, characterized in that: The rear module (1) further comprises a rear mold body (12), the rear mold core (11) being embedded in the rear mold body (12) and being detachably connected to the rear mold body (12), and the front module (2) further comprises a front mold body (22), the front mold core (21) being embedded in the front mold body (22) and being detachably connected to the front mold body (22).

3. The tool for making the R angle of the inner cavity of a bent pipe according to claim 2, characterized in that: The rear module (1) further comprises a rear template (13) and a support plate (14), wherein the number of the support plates (14) is two, the rear mold body (12) and the rear template (13) are connected together via the two support plates (14), and the rear module (1) is connected to an external structure via the rear template (13); the front module (2) further comprises a front template (23), wherein the front template (23) is connected to the front mold body (22), and the front module (2) is connected to an external structure via the front template (23).

4. The tool for making the R angle of the inner cavity of a bent pipe according to claim 1, characterized in that: The sliding structure (7) includes a slider assembly (71) and a clamping strip (72), wherein the number of the clamping strips (72) is two. A slideway for the slider assembly (71) to slide is provided on the rear mold core (11), and the displacement of the slider assembly (71) in the depth direction of the slideway is limited by the two clamping strips (72). The head ends of the positioning pin (3) and the guide pin (4) are both connected to a group of the slider assemblies (71). The slider assembly (71) is connected to an external structure and moves under the drive of the external structure to drive the positioning pin (3) and the guide pin (4) to move.

5. The tool for making the R angle of the inner cavity of a bent pipe according to claim 1, characterized in that: The rear module (1) further comprises an ejector structure (15), the ejector structure (15) comprising an ejector plate (151) and a plurality of first ejectors (152); the first rear molding groove (111) is provided with a first through hole (153) at a corresponding position of each of the first ejector pins (152); the head end of the first ejector pin (152) is connected to the ejector plate (151); the needle end of the first ejector pin (152) is passed through the first through hole (153) and blocks the first through hole (153); an external force pushes the ejector plate (151) forward so that the ejector plate (151) moves toward the rear mold core (11) so that the needle end of the first ejector pin (152) passes through the first through hole (153) and enters the injection molding cavity and ejects the object in the injection molding cavity.

6. The tool for making the R angle of the inner cavity of a bent pipe according to claim 1, characterized in that: The invention also comprises a plastic part molding structure (8), wherein the plastic part molding structure (8) comprises a plastic part rear mold (81) and a plastic part front mold (82), wherein the plastic part rear mold (81) and the plastic part front mold (82) are respectively and correspondingly embedded in the rear mold core (11) and the front mold core (21), wherein the plastic part rear mold (81) is provided with a second rear molding groove (811), and the plastic part front mold (82) is provided with a second front molding groove (821), and the second rear molding groove (811) and the second front molding groove (821) can form a plastic part molding cavity matching the shape of the plastic part (5) when enclosed, and the rear mold core (11) is provided with a second flow channel (114), and the two ends of the second flow channel (114) are respectively connected to the plastic part molding cavity and the external feeding structure.

7. The tool for making the R angle of the inner cavity of a bent pipe according to claim 6, characterized in that: The plastic part molding structure (8) further comprises a plurality of second ejector pins (83); the second post-molding groove (811) is provided with a second through hole (812) at a corresponding position of each second ejector pin (83); the needle end of the second ejector pin (83) is passed through the second through hole (812) and blocks the second through hole (812); external force pushes the plurality of second ejector pins (83) forward so that the needle end of the second ejector pin (83) passes through the second through hole (812) and enters the plastic part molding cavity and ejects the object in the plastic part molding cavity.

8. The tool for making the R angle of the inner cavity of a bent pipe according to claim 1, characterized in that: The needle end of the positioning pin (3) is provided with a cross-shaped groove, and one end of the plastic part (5) connected to the positioning pin (3) is provided with a cross-shaped end matched with the cross-shaped groove.

9. The tool for making the R angle of the inner cavity of a bent pipe according to claim 1, characterized in that: A cylindrical groove is formed at the needle end of the guide needle (4), and a cylindrical end matched with the cylindrical groove is formed at one end of the plastic part (5) connected to the guide needle (4).

10. A process for making an R angle of an inner cavity of a curved pipe, which uses the tool for making an R angle of an inner cavity of a curved pipe as claimed in claim 1, characterized in that: The specific steps include: Step a. injecting a plastic part through a plastic part molding structure; Step b. placing the plastic part obtained in step a in the injection molding cavity, connecting one end of the plastic part to the needle end of the positioning needle for positioning; Step c. Pushing the guide pin to the other end of the plastic part so that the plastic part is connected to the needle end of the guide pin; Step d. Close the rear module and the front module, inject the metal material, and after cooling, open the mold to take out the injection blank with the plastic part; Step e. Soak the injection molded product in the solution, and the solution and the plastic part undergo a chemical reaction to remove the plastic part. The inner cavity of the injection molded product forms a cavity that is the same as the outer shape of the plastic part, and an R angle is generated.

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