Tube molding device and tube manufacturing method using the same

Abstract

To shorten a cooling time of a hollow molded product in a mold when manufacturing a tube using floating core molding.SOLUTION: A tube forming device (5) includes a mold (10). The mold is provided with: a resin supply path (14) that introduces a resin (R) sent from a resin injection machine (50) into a cavity (12) in the mold; a pressure port (16) that opens at one end of a longitudinal direction of the cavity; a core (20) that is placed at a position corresponding to the opening of the pressure port in the cavity; a discharge flow path (28) that opens at the other end of the longitudinal direction of the cavity; and flow path opening means (32) that connects a hollow portion (3) formed in the resin by movement of the core to the discharge flow path. In the molding device, after the movement of the core is completed in the mold, a pressurized fluid is circulated through the hollow portion to cool the resin.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a tube forming apparatus and a tube manufacturing method using the same. [Background technology]

[0002] Floating core molding is a known technique for manufacturing resin tubes. In floating core molding, a mold is used to form an internal cavity with a pressure port at one end and an outlet at the other end. A core is set in the cavity at a position corresponding to the pressure port, and molten resin is injected into the cavity. After that, the core is moved toward the outlet by pressure from the pressure port, forming a hollow resin, which is then pressed against a molding surface that defines the cavity and solidified.

[0003] An example of a method for manufacturing a tube using such floating core molding is disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 08-230066 Summary of the Invention [Problem to be solved by the invention]

[0005] In the manufacture of tubular bodies, shortening the molding cycle is required to improve productivity. The molding cycle includes the injection time, cooling time, time to remove the molded product, and time to open and close the mold. Of these, the cooling time accounts for the largest part of the molding cycle. The cooling time is the time from when the molten resin fills the cavity until it solidifies. In order to shorten the molding cycle, it is essential to shorten the cooling time.

[0006] An object of the present disclosure is to shorten the cooling time of a hollow molded article in a mold when manufacturing a tube using floating core molding. [Means for solving the problem]

[0007] In order to achieve the above-mentioned objective, the technology disclosed herein forms a hollow portion by passing resin filled in a mold cavity through a core, and then cools the resin by circulating a pressurized fluid through the hollow portion.

[0008] Specifically, a first aspect of the present disclosure relates to an apparatus for molding a resin pipe. The pipe molding apparatus of the first aspect includes a mold having a cavity for molding the pipe, a resin injector that injects molten resin into the cavity, and a fluid injector that injects pressurized fluid into the cavity. The mold is provided with a resin supply passage through which resin sent from the resin injector is introduced into the cavity, a pressure port that opens at one longitudinal end of the cavity and introduces pressurized fluid sent from the fluid injector into the cavity, a core that is positioned in the cavity at a position corresponding to the opening of the pressure port and moves inside the resin introduced into the main cavity portion toward the other longitudinal end of the cavity due to the pressure of the pressurized fluid introduced from the pressure port, and a discharge passage that opens at the other longitudinal end of the cavity and discharges the pressurized fluid from the cavity to the outside. The tube molding device includes a flow path opening means for connecting the hollow portion formed in the resin by the movement of the core with the discharge flow path, and after the movement of the core is completed in the mold, the tube molding device introduces pressurized fluid from the pressure port while discharging pressurized fluid from the discharge flow path, and cools the resin by circulating the pressurized fluid through the hollow portion.

[0009] A second aspect of the present disclosure is the tube molding apparatus of the first aspect, wherein the hollow molded product having the hollow portion molded in the cavity includes a product portion that forms the tube and an unnecessary portion other than the product portion. In this tube molding apparatus, the flow path opening means forms an opening hole in the unnecessary portion of the hollow molded product that connects the hollow portion to the discharge flow path.

[0010] A third aspect of the present disclosure is a tube molding apparatus according to the first or second aspect, wherein the mold is provided with a housing having an outlet opening on the outer peripheral surface of the cavity. In this tube molding apparatus, the flow path opening means includes a piercing member housed in the housing and an actuator that displaces the piercing member between an advanced position where the piercing member is advanced from the outlet opening into the cavity and a retracted position where the piercing member is retracted to the rear of the housing portion relative to the outlet opening. In this tube molding apparatus, when the piercing member is in the retracted position, a portion of the housing portion between the piercing member and the outlet opening constitutes a part of the discharge flow path.

[0011] A fourth aspect of the present disclosure is a tube molding apparatus according to any one of the first to third aspects, wherein the mold further includes a partition that divides the cavity into a main cavity portion and a sub-cavity portion. In this tube molding apparatus, the partition is switchable between a closed state that blocks the space between the main cavity portion and the sub-cavity portion and an open state that connects the main cavity portion and the sub-cavity portion. A gate and a pressure port that form the resin supply path are each open in the main cavity portion. With the partition in the closed state to separate the cavity, the tube molding apparatus introduces the molten resin through the gate to fill the main cavity portion, and then switches the partition to the open state to inject pressurized fluid through the pressure port to move the core to the sub-cavity portion.

[0012] A fifth aspect of the present disclosure is a tube molding apparatus according to the fourth aspect, wherein the mold is provided with a housing having an outlet opening on the outer peripheral surface of the cavity. In this tube molding apparatus, the flow path opening means includes a piercing member housed in the housing and an actuator that displaces the piercing member between an advanced position where it advances from the outlet opening into the cavity and a retracted position where it retracts further back from the outlet opening into the housing. In this tube molding apparatus, when the piercing member is in the retracted position, a portion of the housing between the piercing member and the outlet opening constitutes a part of the discharge flow path. The piercing member is a plate-like member and is provided in combination with the partition.

[0013] A sixth aspect of the present disclosure is the tubular body molding apparatus according to the first or second aspect, wherein the core also serves as the flow path opening means.

[0014] A seventh aspect of the present disclosure is the tubular body molding apparatus of the first aspect, wherein the mold is provided with a core stopper that stops movement of the core.

[0015] An eighth aspect of the present disclosure is a tube molding apparatus according to the seventh aspect, wherein the cavity includes a main cavity portion for molding a product portion of the tube from a hollow molded product having the hollow portion to be molded in the cavity, and a sub-cavity portion for molding an unnecessary portion of the hollow molded product other than the product portion. The core stopper is provided in the sub-cavity portion. The discharge flow path opens into a portion of the sub-cavity portion located on the opposite side of the main cavity portion from the core stopper. The sub-cavity portion has an enlarged portion at a location where the core stopped by the core stopper is located, the enlarged portion having a cross-sectional area in a direction perpendicular to the longitudinal direction of the cavity that is larger than that of the main cavity portion. After the core is stopped by the core stopper, pressurized fluid introduced from the pressurization port flows around the core in the enlarged portion and forms an internal space connected to the hollow portion on the discharge flow path side of the sub-cavity portion relative to the core stopper.

[0016] A ninth aspect of the present disclosure is the tubular body molding apparatus of the eighth aspect, wherein the fluid injector also serves as the flow path opening means.

[0017] A tenth aspect of the present disclosure is the tubular body molding apparatus according to any one of the first to ninth aspects, wherein the pressurized fluid is a gas.

[0018] An eleventh aspect of the present disclosure is directed to a method for manufacturing a tube using the tube-forming apparatus according to any one of the first to tenth aspects. a resin introducing step of introducing pressurized fluid from the fluid injector into the cavity through the pressure port, thereby extruding the resin from the core disposed at one end of the cavity toward the other end of the cavity; a flow path opening step of connecting a hollow portion formed in the resin by the movement of the core with the discharge flow path; a cooling step of introducing pressurized fluid from the pressure port while discharging the pressurized fluid from the discharge flow path after the movement of the core is completed in the mold, thereby cooling the resin; and a post-processing step of removing an unnecessary portion of the hollow molded product other than the product portion that forms the molded product.

[0019] A twelfth aspect of the present disclosure is the method for manufacturing a tube according to the eleventh aspect, wherein in the extrusion step, movement of the core is stopped by a core stopper provided in the mold.

[0020] A thirteenth aspect of the present disclosure is a method for manufacturing a tube body according to the twelfth aspect, wherein in the cooling step, the pressurized fluid introduced from the pressurized port is passed around the core stopped by the core stopper and flows through the core stopper to a portion of the cavity located on the opposite side of the pressurized port, forming an internal space connected to the hollow portion in that portion, and the pressurized fluid that has flowed through the internal space is discharged from the discharge flow path.

[0021] A fourteenth aspect of the present disclosure is a method for manufacturing a tube body according to the thirteenth aspect, wherein in the flow path opening step, the resin is broken by a pressurized fluid introduced from the pressure port, thereby connecting the hollow portion to the discharge flow path. [Effects of the Invention]

[0022] According to a first aspect of the present disclosure, the flow path opening means connects the hollow portion formed in the resin in the cavity by the movement of the core with the discharge flow path. After the core has moved completely in the mold, pressurized fluid is introduced through the pressure port while being discharged through the discharge flow path, thereby circulating the pressurized fluid through the hollow portion formed in the resin in the cavity, thereby cooling the resin. This allows the hollow molded product to be cooled efficiently within the mold, shortening the cooling time for the hollow molded product within the mold.

[0023] According to a second aspect of the present disclosure, the flow path opening means forms an open hole in an unnecessary portion of the hollow molded product. This means that no open hole is formed in the product portion that forms the tubular body. This reduces the risk of leakage of the fluid flowing inside the tubular body as a finished product. Furthermore, if an open hole is formed in the tubular body, there is a risk of the tubular body being destroyed starting from the open hole. However, since the tubular body does not have any open holes, such destruction of the tubular body can be prevented.

[0024] According to a third aspect of the present disclosure, the flow path opening means includes a punching member and an actuator. The punching member is housed in a housing provided in the mold. The housing has an outlet opening on the outer periphery of the cavity. The actuator displaces the punching member between an advanced position, in which the punching member is advanced into the cavity through the outlet opening, and a retracted position, in which the punching member is retracted toward the rear of the housing from the outlet opening. When the punching member is in the retracted position, the portion of the housing between the punching member and the outlet opening forms a part of the discharge flow path. Thus, when introducing molten resin into the cavity, the punching member is housed in the housing, and after the core movement is completed, the actuator advances the punching member to the advanced position, thereby forming an open hole in the resin that connects to the hollow portion. After forming the open hole in the resin in this manner, the actuator retracts the punching member to the retracted position, thereby opening the hollow portion of the resin and the discharge flow path through the open hole. Therefore, the discharge flow path and the flow path opening means can be provided together with a relatively simple configuration.

[0025] According to a fourth aspect of the present disclosure, with the partition closed to separate the cavity, molten resin is introduced into the main cavity through the gate to fill it, and then the partition is opened and pressurized fluid is injected through the pressure port to move the core into the sub-cavity. This ensures that the amount of resin necessary to mold the tube is secured in the main cavity before the hollow portion is formed. This allows the tube-forming product portion of the hollow molded product molded in the mold to be suitably molded in the main cavity.

[0026] According to a fifth aspect of the present disclosure, a perforating member 34 is provided in combination with the partition 22. This allows the partition and the perforating member to be arranged in the same location in the mold, thereby increasing the degree of freedom in layout related to mold design.

[0027] According to a sixth aspect of the present disclosure, the core also serves as the flow path opening means. This eliminates the need to provide a mold with a separate component for realizing the flow path opening means. This reduces the number of mold components and the cost of the tube molding device.

[0028] According to a seventh aspect of the present disclosure, a core stopper is provided in the mold, and the core is stopped by the core stopper. The core, whose movement is stopped by the core stopper, remains inside the hollow molded product having a hollow portion molded in the cavity. Therefore, the core can be relatively easily recovered.

[0029] According to an eighth aspect of the present disclosure, an expansion section is provided in a sub-cavity section of the cavity, which molds the unnecessary portion of the hollow molded product, at a location where the core stopped by the core stopper is located. The cross-sectional area of ​​the expansion section is larger than the cross-sectional area of ​​the main cavity section, which molds the product portion of the hollow molded product. This facilitates the flow of resin around the core in the longitudinal direction of the cavity. Pressurized fluid introduced from the pressure port flows around the core in the expansion section, forming an internal space connected to the hollow section on the discharge flow path side of the core stopper in the sub-cavity section. This allows a structure in which the pressurized fluid introduced from the pressure port is distributed downstream of the core stopper in the sub-cavity section and discharged from the discharge flow path to be relatively easily realized.

[0030] According to a ninth aspect of the present disclosure, the fluid injector also functions as the flow path opening means. This eliminates the need to provide a separate component for implementing the flow path opening means in the mold, for example, separate from the fluid injector. This simplifies the mold structure and reduces the number of components required for the tube molding device. As a result, the cost of the tube molding device can be reduced.

[0031] According to a tenth aspect of the present disclosure, a gas is used as the pressurized fluid. If a liquid is used as the pressurized fluid, the liquid remaining in the mold will overflow when the resin molded product is demolded, and after the resin molded product is demolded, the liquid remaining on the molding surface of the mold must be removed and dried, which increases the number of steps required to manufacture the tube. In contrast, if a gas is used as the pressurized fluid, it is easier to handle than a liquid, and the number of steps required to remove the pressurized fluid from the mold does not increase.

[0032] According to an eleventh aspect of the present disclosure, a hollow portion formed in the resin by the movement of the core is connected to a discharge flow path. After the core has moved completely in the mold, pressurized fluid is introduced through the pressurized port while being discharged through the discharge flow path, allowing the pressurized fluid to flow through the hollow portion and cool the resin. This allows the hollow molded product to be efficiently cooled within the mold, shortening the cooling time for the hollow molded product within the mold. This improves the molding cycle required for manufacturing a tubular body.

[0033] According to a twelfth aspect of the present disclosure, the movement of the core is stopped by a core stopper provided in the mold. The core whose movement is stopped by the core stopper remains inside the hollow molded product having a hollow portion molded in the cavity. Therefore, the core can be relatively easily recovered.

[0034] According to a thirteenth aspect of the present disclosure, pressurized fluid introduced through the pressure port flows around the core stopped by the core stopper to a portion of the cavity located on the opposite side of the pressure port via the core stopper, and is then discharged from the discharge passage through an internal space formed in that portion. This allows the main cavity to be made longer than when the discharge passage opens closer to the main cavity than the core stopper, which is advantageous for making the mold more compact.

[0035] According to a fourteenth aspect of the present disclosure, in the flow path opening step, pressurized fluid introduced from the pressure port breaks the resin, thereby connecting the hollow portion to the discharge flow path. This eliminates the need to provide a separate component for connecting the hollow portion to the discharge flow path, such as by providing the component in the mold. This simplifies the mold structure and reduces the number of components required for the tube molding device. As a result, the cost of the tube molding device can be reduced. [Brief explanation of the drawings]

[0036] [Figure 1] FIG. 1 is a cross-sectional view illustrating the configuration of a tube molding apparatus according to the first embodiment. [Figure 2]FIG. 2 is a cross-sectional view illustrating a resin introducing step in the method for manufacturing a tube body according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view illustrating an extrusion step in the manufacturing method of the tube body of the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view illustrating a flow path opening step in the method for manufacturing a tubular body according to the first embodiment. [Figure 5] FIG. 5 is a cross-sectional view illustrating a cooling step in the method for manufacturing a tube according to the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view illustrating a post-treatment step in the method for manufacturing a tube according to the first embodiment. [Figure 7] FIG. 7 is a cross-sectional view illustrating the configuration of a tube molding device according to the second embodiment. [Figure 8] FIG. 8 is a cross-sectional view illustrating a resin introducing step in the method for manufacturing a tube according to the second embodiment. [Figure 9] FIG. 9 is a cross-sectional view illustrating an extrusion step in the manufacturing method of the tube body of the second embodiment. [Figure 10] FIG. 10 is a cross-sectional view illustrating a flow path opening step in the method for manufacturing a tube according to the second embodiment. [Figure 11] FIG. 11 is a cross-sectional view illustrating a cooling step in the method for manufacturing a tube according to the second embodiment. [Figure 12] FIG. 12 is a cross-sectional view illustrating a post-treatment step in the method for manufacturing a tube according to the second embodiment. [Figure 13] FIG. 13 is a cross-sectional view illustrating the configuration of a tube molding device according to the third embodiment. [Figure 14] FIG. 14 is a cross-sectional view illustrating a resin introducing step in the method for manufacturing a tube according to the third embodiment. [Figure 15] FIG. 15 is a cross-sectional view illustrating an extrusion step in the manufacturing method of the tube body of the third embodiment. [Figure 16] FIG. 16 is a cross-sectional view illustrating a flow path opening step in the method for manufacturing a tubular body according to the third embodiment. [Figure 17]FIG. 17 is a cross-sectional view illustrating a cooling step in the method for manufacturing a tube according to the third embodiment. [Figure 18] FIG. 18 is a cross-sectional view illustrating a post-treatment step in the method for manufacturing a tube according to the third embodiment. [Figure 19] FIG. 19 is a cross-sectional view illustrating the configuration of a tube molding apparatus according to the fourth embodiment. [Figure 20] FIG. 20 is a cross-sectional view illustrating a resin introducing step in the method for manufacturing a tube according to the fourth embodiment. [Figure 21] FIG. 21 is a cross-sectional view illustrating an extrusion step and a flow path opening step in the manufacturing method of the tubular body of the fourth embodiment. [Figure 22] FIG. 22 is a cross-sectional view illustrating a post-treatment step in the method for manufacturing a tube according to the fourth embodiment. [Figure 23] FIG. 23 is a schematic view illustrating the configuration of a tube molding device according to the fifth embodiment. [Figure 24] FIG. 24 is a cross-sectional view of the mold taken along line XXIV-XXIV in FIG. [Figure 25] FIG. 25 is a cross-sectional view of the mold taken along line XXV-XXV in FIG. [Figure 26] FIG. 26 is a schematic view illustrating a resin introducing step in the method for manufacturing a tube according to the fifth embodiment. [Figure 27] FIG. 27 is a schematic view illustrating the extrusion step in the manufacturing method of the tube of the fifth embodiment. [Figure 28] FIG. 28 is a schematic view illustrating a flow path opening step in the manufacturing method of the tubular body according to the fifth embodiment. [Figure 29] FIG. 29 is a cross-sectional view of the mold taken along line XXIX-XXIX in FIG. [Figure 30] 30 is a cross-sectional view of the mold taken along line XXX-XXX in FIG. [Figure 31] FIG. 31 is a schematic view illustrating the configuration of a tube molding device according to a modified example of the fifth embodiment. [Figure 32] 32 is a cross-sectional view of the mold taken along line XXXII-XXXII in FIG. [Figure 33] FIG. 33 is a schematic view illustrating a flow path opening step in a manufacturing method of a tubular body according to a modified example of the fifth embodiment. [Figure 34] FIG. 34 is a cross-sectional view of the mold taken along line XXXIV-XXXIV in FIG. [Figure 35] FIG. 35 is a schematic view illustrating the configuration of a tube molding device according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0037] Exemplary embodiments will be described in detail below with reference to the drawings. In the following embodiments, a tube molding apparatus and manufacturing method according to the present disclosure will be described using an example in which gas is used as a pressurized fluid in floating core molding. Note that the drawings are intended to conceptually explain the technology of the present disclosure. Therefore, in the drawings, dimensions, ratios, or numbers may be exaggerated or simplified to facilitate understanding of the technology of the present disclosure.

[0038] First Embodiment The pipe molding apparatus 5 of this embodiment 1 is an apparatus for molding a resin pipe 1. The pipe 1 molded by the molding apparatus 5 is used, for example, as a water pipe for carrying engine cooling water, or as a pipe for carrying blow-by gas or EGR (Exhaust Gas Recirculation) gas. The pipe 1 has a hollow portion 3 for passing a fluid such as a gas or a liquid.

[0039] The pipe body 1 may be a straight pipe that extends straight, or may be a curved or bent pipe. The pipe body 1 may be formed by integrally molding a pipe body and a branch pipe section that branches off from the pipe body. The synthetic resin that forms the pipe body 1 is selected arbitrarily depending on the application of the pipe body 1. Examples of such synthetic resins include polyamide resins (PA) such as nylon 6 and nylon 66, polyphenylene sulfide (PPS), and polypropylene (PP).

[0040] -Tube molding equipment- 1, the tube molding apparatus 5 includes a mold 10, a resin injector 50, a gas injector 60, and a control unit 70. The gas injector 60 is an example of a fluid injector.

[0041] <Mold> The mold 10 has a cavity 12 for molding the tubular body 1. Although not shown, the mold 10 is equipped with a fixed mold and a movable mold. The fixed mold is fixed in a fixed position. The movable mold is provided so that it can move toward and away from the fixed mold. The cavity 12 is formed between the fixed mold and the movable mold by closing the two molds. A hollow molded product 100 having a hollow portion 3 molded in the cavity 12 includes a product portion 102 that forms the tubular body 1 and an unnecessary portion 104 other than the product portion 102 (see Figure 6).

[0042] The cavity 12 is a cylindrical space having a predetermined inner diameter and includes a main cavity portion 12a and a sub-cavity portion 12b. The main cavity portion 12a is a hollow portion for molding the product portion 102. The main cavity portion 12a is formed as a space having an extent corresponding to the outer shape of the tube body 1. The sub-cavity portion 12b is a hollow portion into which excess resin R extruded from the main cavity portion 12a together with the core 20 is discharged. The sub-cavity portion 12b is connected to the main cavity portion 12a so as to extend continuously from one end of the main cavity portion 12a.

[0043] The portion of the main cavity portion 12a closer to the sub-cavity portion 12b and the sub-cavity portion 12b are formed to have a smaller cross-sectional opening area in a direction perpendicular to the longitudinal direction of the cavity 12 than the other portions of the main cavity portion 12a. In the example shown in Fig. 1, the main cavity portion 12a and the sub-cavity portion 12b are shown as being simply straight, but the main cavity portion 12a and the sub-cavity portion 12b may each have a curved or bent shape.

[0044] The mold 10 is provided with a resin supply path 14. The resin supply path 14 is a flow path for introducing the resin R sent from the resin injector 50 into the cavity 12. The resin supply path 14 is provided using a direct gate system and is configured to include a sprue 14a and a gate 14b. The sprue 14a opens onto the outer surface of the mold 10. The gate 14b communicates with the sprue 14a and opens onto the outer peripheral surface of the main cavity portion 12a. The resin supply path 14 may also use other methods for providing the gate 14b, such as a side gate system.

[0045] The mold 10 is provided with a pressure port 16. The pressure port 16 is a flow path for introducing the gas G sent from the gas injector 60 into the cavity 12. One end of the pressure port 16 opens to one end of the cavity 12 in the longitudinal direction. Specifically, the one end of the pressure port 16 opens to an end of the main cavity portion 12a located opposite the sub-cavity portion 12b. A setting portion 18 for holding a core 20 is provided at the opening of the pressure port 16 on the cavity 12 side. The other end of the pressure port 16 opens to the outer surface of the mold 10.

[0046] A core 20 is provided in the mold 10. The core 20 is set in the setting section 18 and placed in the cavity 12 with its back to the pressure port 16. The core 20 has an outer diameter smaller than the inner diameter of the main cavity section 12a. In this example, the outer diameter of the core 20 is smaller than the inner diameter of the sub-cavity section 12b. The shape of the core 20 may be spherical as shown in the figure, or may be other shapes such as bullet-shaped or hemispherical as long as the maximum diameter is smaller than the inner diameter of the main cavity section 12a. The core 20 may be made of metal or resin. The core 20 may be made of ceramic or an elastic material such as silicone.

[0047] The mold 10 is provided with a partition 22 and a first actuator 24. The partition 22 is a metal plate-like member that divides the cavity 12 into a main cavity portion 12a and a sub-cavity portion 12b. A first housing portion 26 that houses the partition 22 is formed at the boundary between the main cavity portion 12a and the sub-cavity portion 12b in the mold 10. The first housing portion 26 opens to the outer peripheral surface of the cavity 12. The partition 22 is housed in the first housing portion 26 so as to be able to freely move in and out of the cavity 12. The partition 22 is switchable between a closed state that blocks the main cavity portion 12a and the sub-cavity portion 12b and an open state that allows communication between them.

[0048] The first actuator 24 is connected to the partition 22 and is configured to be able to advance and retreat the partition 22 relative to the cavity 12. The first actuator 24 may be an electric or hydraulic device. The first actuator 24 advances the partition 22 into the cavity 12, thereby closing off the space between the main cavity portion 12a and the sub-cavity portion 12b. The first actuator 24 retreats the partition 22 from the cavity 12 into the first storage portion 26, thereby connecting the main cavity portion 12a and the sub-cavity portion 12b.

[0049] The mold 10 is provided with a discharge flow path 28. The discharge flow path 28 is a flow path for discharging the gas G inside the cavity 12 to the outside. One end of the discharge flow path 28 opens to the other end side in the longitudinal direction of the cavity 12. Specifically, one end of the discharge flow path 28 opens to the outer peripheral surface of a portion of the sub-cavity portion 12b located on the opposite side from the main cavity portion 12a. The other end of the discharge flow path 28 opens to the outer surface of the mold 10. A gas pipe 30 is connected to the outer surface opening of the discharge flow path 28 in the mold 10.

[0050] The mold 10 is provided with a flow path opening means 32. The flow path opening means 32 is a means for connecting the hollow portion 3 formed in the resin R in the cavity 12 by movement of the core 20 with the discharge flow path 28. In this example, the flow path opening means 32 has a punching member 34 and a second actuator 36. A second accommodating portion 38 that accommodates the punching member 34 is provided around the sub-cavity portion 12b in the mold 10. The second accommodating portion 38 is configured to include a part of the discharge flow path 28. A part of the discharge flow path 28 is a common path 40 that also serves as a passage through which the punching member 34 is inserted.

[0051] The second accommodating portion 38 has an inlet / outlet opening 42 that opens to the outer peripheral surface of the sub-cavity portion 12b. The inlet / outlet opening 42 is also an opening of the discharge flow path 28 facing the inside of the cavity 12. The piercing member 34 is a sharp rod-shaped member that is accommodated in the second accommodating portion 38 so as to be able to freely intrude into and retract from the cavity 12. The piercing member 34 pierces the wall of the resin R that constitutes the unnecessary portion 104 of the hollow molded product 100, thereby forming an open hole 106 in the wall of the resin R that connects the hollow portion 3 and the discharge flow path 28.

[0052] The second actuator 36 is connected to the piercing member 34 and is configured to be able to advance and retract the piercing member 34 relative to the cavity 12. The second actuator 36 may be an electric or hydraulic device. The second actuator 36 displaces the piercing member 34 between an advanced position and a retracted position. The advanced position is a position where the piercing member 34 is advanced into the cavity 12 from the inlet / outlet 42 so as to penetrate the wall of the resin R that constitutes the unnecessary portion 104 of the hollow molded product 100. The retracted position is a position where the piercing member 34 is retracted further back into the second housing section 38 than the inlet / outlet 42 so as to be removed from the common path 40. When the piercing member 34 is in the retracted position, the portion of the second housing section 38 that forms the common path 40 between the piercing member 34 and the inlet / outlet 42 constitutes a part of the discharge flow path 28.

[0053] <Resin injection machine> The resin injector 50 injects molten resin R into the cavity 12. The resin injector 50 heats and melts the resin R, which is a molding material. The resin injector 50 injects a predetermined amount of the molten resin R into the cavity 12 in the mold 10 via the resin supply path 14 (sprue 14a, gate 14b, etc.). The resin injector 50 includes a cylinder 52, a screw 54, and a drive unit 56.

[0054] The cylinder 52 is a cylindrical member. A nozzle 53 is provided at the tip of the cylinder 52. The nozzle 53 is connected to the outer opening of the sprue 14a in the mold 10. Although not shown, a hopper for supplying resin material such as pellets is provided at the rear side of the cylinder 52. The cylinder 52 is also provided with a heater. The heater heats the resin material inside the cylinder 52. The cylinder 52 heats the resin R to a molten state and accumulates the molten resin R inside.

[0055] The screw 54 is housed in the cylinder 52 so as to be positioned coaxially with the cylinder 52. The screw 54 rotates and moves back and forth within the cylinder 52. The screw 54 feeds the molten resin R in the cylinder 52 forward by its rotational movement, and is displaced within the cylinder 52 by its forward and backward movement. The resin R fed by the screw 54 is extruded from the cylinder 52 and injected from the nozzle 53 into the resin supply path 14 (sprue 14a).

[0056] The drive unit 56 is connected to the screw 54 and rotates and moves the screw 54 forward and backward. The drive unit 56 includes a belt transmission mechanism and an electric motor. The resin injector 50 injects molten resin R from the nozzle 53 by advancing the screw 54 from its retracted position. The resin R injected from the nozzle 53 is introduced into the cavity 12 in the mold 10 via the resin supply path 14.

[0057] <Gas injector> After the main cavity 12a has been completely filled with the molten resin R, the gas injector 60 injects gas G as a pressurized fluid at a predetermined pressure into the resin R filled in the main cavity 12a. The gas injector 60 is connected to the outer surface opening of the pressurization port 16 in the mold 10. The gas injector 60 includes a compressor. The gas G handled by the gas injector 60 in this example is nitrogen gas having a temperature around room temperature. Nitrogen gas is an example of an inert gas.

[0058] <Control unit> The control unit 70 is a controller based on a well-known microcomputer. The control unit 70 has a processor and a memory. The memory stores various programs and data. The processor reads and executes the programs from the memory, and controls the molding operation of the tube body 1 by the molding device 5.

[0059] The control unit 70 is connected to the opening / closing mechanism (not shown) of the mold 10, the first actuator 24, the second actuator 36, the resin injector 50, and the gas injector 60. The control unit 70 controls the mold opening, closing, and clamping operations by the opening / closing mechanism of the mold 10, the advance / retract movement of the partition body 22 by the first actuator 24, the advance / retract movement of the perforating member 34 by the second actuator 36, the injection operation of the resin R by the resin injector 50, and the injection operation of the gas G by the gas injector 60.

[0060] The control unit 70 operates the opening and closing mechanism of the mold 10 to clamp the mold 10. In the clamped mold 10, the control unit 70 operates the first actuator 24 to advance the partition 22 into the cavity 12 to close the mold 10. Then, the control unit 70 operates the resin injector 50 to inject molten resin R into the main cavity portion 12a, filling the main cavity portion 12a with the resin R.

[0061] When filling of the resin R into the main cavity portion 12a is completed, the control unit 70 operates the first actuator 24 to retract the partition 22 into the first storage portion 26 and set it in an open state. Furthermore, the control unit 70 operates the gas injector 60 to inject gas G into the cavity 12. This injection of gas G pressurizes the core 20, causing it to move toward the sub-cavity portion 12b, while pushing out the excess resin R in the main cavity portion 12a into the sub-cavity portion 12b. As a result, the trace of the core 20 passing through becomes a hollow portion 3, and the hollow portion 3 is formed inside the resin R.

[0062] After the movement of the core 20 in the mold 10 is completed, the control unit 70 operates the second actuator 36 to advance the piercing member 34 to an advanced position within the cavity 12. This advancement of the piercing member 34 is performed before the unnecessary portion 104 of the hollow molded product 100 in the sub-cavity portion 12b is completely solidified, i.e., while there are still uncured portions. This causes the piercing member 34 to pierce the wall of the resin R that constitutes the unnecessary portion 104 of the hollow molded product 100, forming an open hole 106 that penetrates into the hollow portion 3. The open hole 106 thus formed connects the hollow portion 3 to the discharge flow path 28. The advancement of the piercing member 34 may also be performed after the unnecessary portion 104 of the hollow molded product 100 in the sub-cavity portion 12b has hardened.

[0063] Next, the control unit 70 operates the second actuator 36 to retract the piercing member 34 to the retracted position within the second storage unit 38. As a result, the gas G injected into the resin R flows through the hollow portion 3 and then through the open hole 106 into the discharge flow path 28. The control unit 70 also continues to operate the gas injector 60 to introduce the gas G into the resin R from the pressure port 16 while discharging the gas G from the discharge flow path 28.

[0064] In this way, in the molding device 5, the resin R is cooled by circulating the gas G through the hollow portion 3 formed in the resin in the cavity 12. When the resin R is cooled and solidified, a hollow molded article 100 including a product portion 102 forming the tubular body 1 is molded in the cavity 12. The control unit 70 operates the opening and closing mechanism of the mold 10 to open the mold 10. Once the mold 10 is opened, the hollow molded article 100 can be removed from the mold 10.

[0065] -Tube body manufacturing method- The tube body 1 is manufactured using the above-mentioned molding device 5. The manufacturing method of the tube body 1 includes a preparation step, a resin introduction step, an extrusion step, a flow path opening step, a cooling step, a demolding step, and a post-processing step.

[0066] In the preparation step, the core 20 is set in the setting section 18 of the mold 10, and then the opening / closing mechanism of the mold 10 is operated to close the mold 10. This forms a cavity 12 in the mold 10, and the core 20 is positioned at a position corresponding to the pressure port 16 of the cavity 12. Furthermore, pressure is applied to the closed mold 10 to close the mold 10. Then, as shown in FIG. 1 , the first actuator 24 is operated to advance the partition 22 into the cavity 12 to close it, and the partition 22 separates the main cavity portion 12a and the sub-cavity portion 12b.

[0067] Next, a resin introducing step is performed. As shown in Fig. 2, in the resin introducing step, the resin injector 50 is operated to introduce molten resin R from the resin injector 50 into the main cavity portion 12a of the cavity 12 of the mold 10 via the resin supply path 14. The resin R is then spread throughout the entire main cavity portion 12a, filling the main cavity portion 12a with the resin R. At this time, the resin R introduced from the gate 14b flows through the main cavity portion 12a, but is blocked by the partition 22 and does not flow into the sub-cavity portion 12b.

[0068] Next, an extrusion step is performed. In the extrusion step, the first actuator 24 is operated to retract the partition 22 into the first storage section 26 to open the gap between the main cavity section 12a and the sub-cavity section 12b, thereby connecting the two cavities 12a and 12b. Next, as shown in FIG. 3, the gas injector 60 is operated to inject gas G from the gas injector 60 through the pressure port 16 into the main cavity section 12a filled with the resin R. This causes the core 20 to move under the pressure of the gas G. At this time, the excess resin R in the main cavity section 12a is extruded into the sub-cavity section 12b by the movement of the core 20.

[0069] In this way, the core 20, which is arranged at one end in the longitudinal direction of the cavity 12 (the end where the pressure port 16 of the main cavity portion 12a is formed), is moved toward the other end in the longitudinal direction of the cavity 12 (the sub-cavity portion 12b side) while extruding the resin R. As the core 20 passes through the inside of the resin R within the cavity 12, a hollow portion 3 is formed in the resin R. In this example, the core 20 moves to the back side of the sub-cavity portion 12b. Therefore, the hollow portion 3 is also formed in the resin R extruded into the sub-cavity portion 12b so that it is continuous with the main cavity portion 12a.

[0070] Next, a flow path opening step is performed. As shown in Fig. 4, in the flow path opening step, the second actuator 36 is operated to advance the piercing member 34 to an advanced position within the cavity 12. This causes the piercing member 34 to pierce the wall of the resin R that constitutes the unnecessary portion 104 of the hollow molded product 100, forming an open hole 106 in the wall of the resin R. Furthermore, as shown in Fig. 5, the second actuator 36 is operated to retract the piercing member 34 to a retracted position within the second storage portion 38. This causes the piercing member 34 to come out of the common path 40, and the hollow portion 3 formed in the resin R and the discharge flow path 28 communicate with each other via the open hole 106.

[0071] Even in this flow path opening step, gas G continues to be introduced from gas injector 60 into hollow portion 3 of resin R in cavity 12, and the resin R is kept pressed against molding surface 13 of mold 10. In the flow path opening step, the introduction of gas G from gas injector 60 into hollow portion 3 of resin R may be temporarily stopped as long as the resin R can be kept pressed against molding surface 13 of mold 10.

[0072] Next, a cooling step is performed. In the cooling step, the gas injector 60 is operated to introduce gas G into the hollow portion 3 formed in the resin R from the pressure port 16. The gas G introduced into the hollow portion 3 of the resin R flows through the open hole 106 to the discharge flow path 28 and is discharged from the discharge flow path 28 to the outside of the mold 10. The gas G discharged to the outside of the mold 10 may be returned to the gas injector 60 after cooling and reused. In this manner, gas G is introduced into the hollow portion 3 of the resin R from the pressure port 16 while being discharged from the discharge flow path 28, causing the gas G to circulate through the hollow portion 3. This cools the resin R in the cavity 12. At this time, gas G is continuously circulated through the hollow portion 3, thereby accelerating the cooling of the resin R. When the resin R is cooled, it solidifies, and a hollow molded product 100 having a hollow portion 3 is molded in the cavity 12.

[0073] Next, a demolding step is performed. In the demolding step, the opening and closing mechanism of the mold 10 is operated to open the mold 10. Then, the hollow molded article 100 is taken out from the opened mold 10.

[0074] Thereafter, a post-processing step is performed. As shown in Fig. 6, in the post-processing step, unnecessary portions 104 other than the product portion 102 constituting the tubular body 1 of the hollow molded article 100 removed from the mold 10 are cut and removed at predetermined positions (the position of the cut line Lc shown by the dashed line in Fig. 6; also shown in Figs. 4 and 5). The unnecessary portions 104 removed at this time include the incidental molded products molded in the sub-cavity portion 12b as well as gate residues.

[0075] In this manner, the tube body 1 can be manufactured.

[0076] -Features of the first embodiment- In the tubular molding apparatus 5 of this embodiment 1, the flow path opening means 32 connects the hollow portion 3 formed in the resin R in the cavity 12 by the movement of the core 20 with the discharge flow path 28. Then, after the movement of the core 20 is completed in the mold 10, the gas G is introduced from the pressure port 16 while being discharged from the discharge flow path 28, and the gas G is circulated through the hollow portion 3 formed in the resin R in the cavity 12, thereby cooling the resin R. This allows the hollow molded article 100 to be cooled efficiently in the mold 10, and the cooling time of the hollow molded article 100 in the mold 10 can be shortened.

[0077] In the tube molding apparatus 5 of this embodiment 1, the flow path opening means 32 forms an open hole 106 in the unnecessary portion 104 of the hollow molded product 100. As a result, the open hole 106 is not formed in the product portion 102 that forms the tube 1 of the hollow molded product 100. This reduces the risk of leakage of the fluid flowing inside the tube 1 as a product. Furthermore, if an open hole 106 is formed in the tube 1, there is a risk that the tube 1 will be damaged starting from the open hole 106. However, since the tube 1 does not have an open hole 106, such damage to the tube 1 can be prevented.

[0078] In the tubular body molding apparatus 5 of this embodiment 1, the flow path opening means 32 has a piercing member 34 and a second actuator 36. The piercing member 34 is housed in a second housing portion 38 provided in the mold 10. The second housing portion 38 has an outlet 42 that opens to the outer peripheral surface of the sub-cavity portion 12b. The second actuator 36 displaces the piercing member 34 between an advanced position where it is advanced into the cavity 12 through the outlet 42, and a retracted position where it is retracted to the inner side of the second housing portion 38 beyond the outlet 42. When the piercing member 34 is in the retracted position, the portion of the second housing portion 38 that forms the common path 40 between the piercing member 34 and the outlet 42 constitutes a part of the discharge flow path 28.

[0079] According to this, when introducing the molten resin R into the cavity 12, the punching member 34 is accommodated in the second accommodation portion 38, and after the movement of the core 20 is completed, the punching member 34 is advanced to an advanced position within the cavity 12 by the second actuator 36, thereby forming an opening 106 in the resin R that connects to the hollow portion 3. After the opening 106 is formed in the resin R in this manner, the punching member 34 is retracted to a retracted position within the second accommodation portion 38 by the second actuator 36, thereby opening the hollow portion 3 of the resin R and the discharge flow path 28 through the opening 106. Therefore, the discharge flow path 28 and the flow path opening means 32 can be provided together with a relatively simple configuration.

[0080] In the tube molding apparatus 5 of this embodiment 1, with the partition 22 in a closed state to partition the cavity 12, molten resin R is introduced through the gate 14b into the main cavity portion 12a to fill it, and then the partition 22 is opened and gas G is injected through the pressure port 16 to move the core 20 to the sub-cavity portion 12b. In this way, the amount of resin R necessary for molding the tube 1 is secured in the main cavity portion 12a before the hollow portion 3 is formed. As a result, the product portion 102 that forms the tube 1 of the hollow molded product 100 molded in the mold 10 can be suitably molded in the main cavity portion 12a.

[0081] In the tube molding apparatus 5 of this embodiment 1, gas G is used as the pressurized fluid. If a liquid is used as the pressurized fluid, the liquid remaining in the mold 10 will overflow when the hollow molded article 100 is demolded, and after the hollow molded article 100 is demolded, it will be necessary to remove and dry the liquid remaining on the molding surface 13 of the mold 10, which increases the number of steps in the manufacture of the tube 1. In contrast, if gas G is used as the pressurized fluid, it is easier to handle than a liquid, and the number of steps in the manufacture of the tube 1 to remove the pressurized fluid from the mold 10 does not increase.

[0082] In the method for manufacturing a tube body according to the first embodiment, the hollow portion 3 formed in the resin R by the movement of the core 20 is connected to the discharge flow path 28. After the movement of the core 20 is completed in the mold 10, the gas G is introduced from the pressure port 16 while being discharged from the discharge flow path 28, and the gas G is circulated through the hollow portion 3, thereby cooling the resin R. This allows the hollow molded article 100 to be efficiently cooled in the mold 10, and the cooling time of the hollow molded article 100 in the mold 10 can be shortened. This improves the molding cycle required for manufacturing the tube body 1.

[0083] Second Embodiment The tubular body molding apparatus 5 of this embodiment 2 differs from the above-mentioned embodiment 1 in the configuration of the cavity 12 and the positions of the discharge flow path 28 and flow path opening means 32. In this embodiment 2, the tubular body molding apparatus 5 is configured in the same manner as the above-mentioned embodiment 1, except for the configuration of the cavity 12 and the positions of the discharge flow path 28 and flow path opening means 32. Therefore, the details of the same components in the molding apparatus 5 will be omitted and will be left to the explanation of the above-mentioned embodiment 1.

[0084] -Tube molding equipment- 7, in the tube molding apparatus 5 of this embodiment 2, the cross-sectional opening area of ​​the portion of the main cavity 12a closer to the sub-cavity 12b and the sub-cavity 12b in a direction perpendicular to the longitudinal direction of the cavity 12 is formed to be smaller than the outer diameter of the core 20. A step 11 is provided in the main cavity 12a at a position closer to the sub-cavity 12b, forming a boundary between a portion with a relatively large inner diameter and a portion with a relatively small inner diameter. The step 11 functions as a stopper that stops the movement of the core 20.

[0085] One end of the discharge flow path 28 opens onto the outer peripheral surface of a portion of the main cavity portion 12a that is closer to the sub-cavity portion 12b. In this example, in the hollow molded product 100 molded in the cavity 12, a portion of the portion molded in the main cavity portion 12a that is closer to the sub-cavity portion 12b also constitutes the unnecessary portion 104. As in the first embodiment, the second storage portion 38 is provided so that the opening of the discharge flow path 28 that faces the inside of the cavity 12 also serves as the outlet port 42. The flow path opening means 32 has a perforating member 34 and a second actuator 36 that are similar to those in the first embodiment.

[0086] The piercing member 34 is housed in the second housing portion 38 so as to be able to freely protrude and retract into the cavity 12. The piercing member 34 pierces the resin R constituting the unnecessary portion 104 of the hollow molded product 100, thereby forming an opening 106 that connects the hollow portion 3 with the discharge flow path 28. The second actuator 36 is connected to the piercing member 34 and is configured to be able to advance and retract the piercing member 34 relative to the cavity 12. When the piercing member 34 is in the retracted position, the portion of the second housing portion 38 that forms the common path 40 between the piercing member 34 and the inlet / outlet 42 constitutes part of the discharge flow path 28.

[0087] -Tube body manufacturing method- The method for manufacturing the tube 1 of this second embodiment also includes a preparation step, a resin introduction step, an extrusion step, a flow path opening step, a cooling step, a demolding step, and a post-treatment step.

[0088] In the preparation step, similarly to the first embodiment, a cavity 12 is formed in the mold 10, a core 20 is placed at a position corresponding to the pressurizing port 16 of the cavity 12, and the mold 10 is clamped. Then, as shown in Fig. 7, the partition 22 is advanced into the cavity 12 to close it, and the main cavity portion 12a and the sub-cavity portion 12b are separated by the partition 22.

[0089] 8, in the next resin introducing step, similar to the first embodiment, molten resin R is introduced from resin injector 50 into cavity 12 via resin supply path 14, and the resin R is spread throughout main cavity portion 12a to fill it. At this time, resin R introduced from gate 14b flows through main cavity portion 12a, but is blocked by partition 22 and does not flow into sub-cavity portion 12b.

[0090] 9, in the next extrusion step, as in the first embodiment, the partition 22 is retracted into the first housing portion 26 to open it, and gas G is injected from the gas injector 60 via the pressure port 16 into the main cavity portion 12a filled with the resin R. By doing so, the core 20 arranged at one end in the longitudinal direction of the cavity 12 (the end of the main cavity portion 12a where the pressure port 16 is formed) is moved toward the other end in the longitudinal direction of the cavity 12 (the side toward the sub-cavity portion 12b) while extruding the resin R. As a result, a hollow portion 3 is formed in the resin R in the cavity 12.

[0091] 10, in the next flow path opening step, similar to the first embodiment, the piercing member 34 is advanced to an advanced position within the cavity 12, and the piercing member 34 is pierced into the wall of the resin R that forms the unnecessary portion 104 of the hollow molded product 100, forming an open hole 106 in the wall of the resin R. Thereafter, as shown in FIG. 11, the piercing member 34 is retracted to a retracted position within the second storage portion 38. This allows the hollow portion 3 formed in the resin R to communicate with the discharge flow path 28 via the open hole 106.

[0092] In the subsequent cooling step, similarly to the first embodiment, gas G is introduced into the hollow portion 3 of the resin R from the pressure port 16 while being discharged from the discharge flow path 28, thereby continuously circulating gas G through the hollow portion 3. This cools the resin R within the cavity 12. The cooling of the resin R is promoted by the flow of gas G through the hollow portion 3. When the resin R is cooled, it solidifies, and a hollow molded article 100 having a hollow portion 3 is molded within the cavity 12.

[0093] In the demolding step that follows, similarly to the first embodiment, the mold 10 is opened and the hollow molded article 100 is removed from the open mold 10. In the subsequent post-processing step, as shown in Fig. 12, similarly to the first embodiment, an unnecessary portion 104 other than the product portion 102 that forms the tubular body 1 of the hollow molded article 100 that has been removed from the mold 10 is cut and removed at a predetermined position (the position of the cut line Lc shown by the dashed dotted line in Fig. 12; also shown in Figs. 10 and 11).

[0094] In this manner, the tube body 1 can be manufactured.

[0095] -Features of the second embodiment- In the tube molding apparatus 5 of this second embodiment, the flow path opening means 32 also connects the hollow portion 3 formed in the resin R in the cavity 12 by the movement of the core 20 with the discharge flow path 28. After the movement of the core 20 is completed in the mold 10, the gas G is introduced from the pressure port 16 while being discharged from the discharge flow path 28, and the gas G is circulated through the hollow portion 3 formed in the resin R in the cavity 12, thereby cooling the resin R. This allows the hollow molded article 100 to be efficiently cooled in the mold 10, and the cooling time of the hollow molded article 100 in the mold 10 can be shortened. In addition, similar effects to those described as features of the first embodiment can be obtained.

[0096] Third Embodiment The tube forming apparatus 5 of this embodiment 3 differs from the above-described embodiment 1 in the configurations of the partition 22, the perforating member 34, and the third actuator 44 that moves the partition 22 and the perforating member 34 forward and backward. In this embodiment 3, the tube forming apparatus 5 is configured similarly to the above-described embodiment 1, except that the configurations of the partition 22, the perforating member 34, and the third actuator 44 differ from those of the above-described embodiment 1. Therefore, the matters relating to the same components in the forming apparatus 5 will be left to the explanation of the above-described embodiment 1, and detailed explanations thereof will be omitted.

[0097] -Tube molding equipment- 13, in the tube molding apparatus 5 of this third embodiment, the partition 22 and the perforating member 34 are provided in combination with each other. The partition 22 is housed in the first housing section 26 so as to be able to freely protrude into and retract from the cavity 12. The perforating member 34 is a sharp plate-like member, and is disposed inside the partition 22 so as to be able to protrude into and retract from the cavity 12 independently of the partition 22. The perforating member 34 may also be a rod-shaped member.

[0098] The partition 22 and the piercing member 34 are connected to a third actuator 44. That is, the partition 22 and the piercing member 34 advance and retreat relative to the cavity 12 by the operation of the common third actuator 44. The third actuator 44 is configured to be able to advance and retreat both the partition 22 and the piercing member 34 relative to the cavity 12. Furthermore, the third actuator 44 is configured to be able to advance and retreat the piercing member 34 relative to the cavity 12 while the partition 22 is housed in the first housing section 26.

[0099] The third actuator 44 closes the gap between the main cavity portion 12a and the sub-cavity portion 12b by advancing both the partition body 22 and the piercing member 34 into the cavity 12. The third actuator 44 retracts both the partition body 22 and the piercing member 34 from the cavity 12 into the first housing portion 26, thereby connecting the main cavity portion 12a and the sub-cavity portion 12b. The third actuator 44 displaces both the partition body 22 and the piercing member 34 to a retracted position where they are retracted further back into the first housing portion 26 than the inlet / outlet 42.

[0100] The third actuator 44 displaces the piercing member 34 from the inlet / outlet 42 to an advanced position advanced into the cavity 12. The third actuator 44 may be an electric or hydraulic device. A part of the discharge flow path 28 is a common path 40 that also serves as a passage through which the partition body 22 and the piercing member 34 are inserted. When the partition body 22 and the piercing member 34 are both in the retracted position, the part of the first housing section 26 that forms the common path 40 between the piercing member 34 and the inlet / outlet 42 constitutes a part of the discharge flow path 28.

[0101] -Tube body manufacturing method- The method for manufacturing a tube body according to the third embodiment also includes a preparation step, a resin introduction step, an extrusion step, a flow path opening step, a cooling step, a demolding step, and a post-treatment step.

[0102] In the preparation step, similarly to the first embodiment, a cavity 12 is formed in the mold 10, a core 20 is placed at a position corresponding to the pressurizing port 16 of the cavity 12, and the mold 10 is clamped. Then, as shown in Fig. 13, the partition 22 and the perforated member 34 are advanced together into the cavity 12 to close it, and the main cavity portion 12a and the sub-cavity portion 12b are separated by the partition 22.

[0103] 14, in the next resin introducing step, similar to the first embodiment, molten resin R is introduced from resin injector 50 into cavity 12 via resin supply path 14, and the resin R is spread throughout main cavity portion 12a to fill it. At this time, resin R introduced from gate 14b flows through main cavity portion 12a, but is blocked by partition 22 and does not flow into sub-cavity portion 12b.

[0104] 15, in the next extrusion step, the third actuator 44 is operated to retract both the partition 22 and the perforating member 34 into the first storage section 26 to open the same, and gas G is injected from the gas injector 60 via the pressure port 16 into the main cavity section 12a filled with the resin R. This moves the core 20, which is located at one end of the longitudinal direction of the cavity 12 (the end of the main cavity section 12a where the pressure port 16 is formed), toward the other end of the longitudinal direction of the cavity 12 (the side toward the sub-cavity section 12b) while extruding the resin R. As a result, a hollow section 3 is formed in the resin R in the cavity 12.

[0105] 16, in the next flow path opening step, the third actuator 44 is operated to advance the piercing member 34 to an advanced position within the cavity 12 while keeping the partition 22 retracted within the first storage portion 26, and the piercing member 34 pierces the wall of the resin R that forms the unnecessary portion 104 of the hollow molded product 100, forming an opening 106 in the wall of the resin R. Thereafter, as shown in FIG. 17, the third actuator 44 retracts both the partition 22 and the piercing member 34 to the retracted position within the first storage portion 26. This allows the hollow portion 3 formed in the resin R to communicate with the discharge flow path 28 via the opening 106.

[0106] In the subsequent cooling step, similarly to the first embodiment, gas G is introduced into the hollow portion 3 of the resin R from the pressure port 16 while being discharged from the discharge flow path 28, thereby continuously circulating gas G through the hollow portion 3. This cools the resin R within the cavity 12. The cooling of the resin R is promoted by the flow of gas G through the hollow portion 3. When the resin R is cooled, it solidifies, and a hollow molded article 100 having a hollow portion 3 is molded within the cavity 12.

[0107] In the demolding step that follows, similarly to the first embodiment, the mold 10 is opened and the hollow molded article 100 is removed from the open mold 10. In the subsequent post-processing step, as shown in Fig. 18, similarly to the first embodiment, an unnecessary portion 104 other than the product portion 102 that forms the tubular body 1 of the hollow molded article 100 that has been removed from the mold 10 is cut and removed at a predetermined position (the position of the cut line Lc shown by the dashed line in Fig. 18; also shown in Figs. 16 and 17).

[0108] In this manner, the tube body 1 can be manufactured.

[0109] -Features of the third embodiment- In the tube molding apparatus 5 of this third embodiment, the flow path opening means 32 also connects the hollow portion 3 formed in the resin R in the cavity 12 by the movement of the core 20 with the discharge flow path 28. After the movement of the core 20 is completed in the mold 10, the gas G is introduced from the pressure port 16 while being discharged from the discharge flow path 28, and the gas G is circulated through the hollow portion 3 formed in the resin R in the cavity 12, thereby cooling the resin R. This allows the hollow molded article 100 to be efficiently cooled in the mold 10, and the cooling time of the hollow molded article 100 in the mold 10 can be shortened. In addition, similar effects to those described as features of the first embodiment can be obtained.

[0110] In the tube molding apparatus 5 of this third embodiment, the perforating member 34 is provided in combination with the partition 22. This allows the partition 22 and the perforating member 34 to be arranged in the same location in the mold 10, increasing the degree of freedom in layout related to mold design. In addition, the perforating member 34 is a plate-shaped member. When the third actuator 44 advances the perforating member 34 to an advanced position within the cavity 12, a relatively large opening 106 connected to the hollow portion 3 is formed in the resin R. This makes it easy to ensure a sufficient flow rate of the gas G circulating in the hollow portion 3.

[0111] Fourth Embodiment The tubular molding apparatus 5 of this embodiment 4 differs from that of the above-described embodiment 1 in the configuration of the flow path opening means 32. In this embodiment 2, the tubular molding apparatus 5 is configured similarly to that of the above-described embodiment 1, except for the configuration of the flow path opening means 32. Therefore, matters relating to the same components in the molding apparatus 5 will be left to the explanation of the above-described embodiment 1, and detailed explanations thereof will be omitted.

[0112] -Tube molding equipment- 19, in the tube molding apparatus 5 of this embodiment 4, the flow path opening means 32 does not have a piercing member 34 and a second actuator 36 as in the above-mentioned embodiment 1. The flow path opening means 32 of this example is the core 20. That is, the core 20 also serves as the flow path opening means 32. Also, the sub-cavity portion 12b of this example is provided to be relatively long.

[0113] The length of the sub-cavity portion 12b need only be long enough to allow the core 20 to break through the resin R filled in the main cavity portion 12a as it moves. When the core 20 moves inside the resin R filled in the main cavity portion 12a due to the pressure of the gas G injected into the cavity 12 from the pressure port 16, the core 20 breaks through the resin R in the sub-cavity portion 12b. This forms a hollow portion 3 in the resin R, and the hollow portion 3 communicates with the discharge flow path 28.

[0114] -Tube body manufacturing method- The method for manufacturing a tube according to the fourth embodiment also includes a preparation step, a resin introduction step, an extrusion step, a flow path opening step, a cooling step, a demolding step, and a post-treatment step.

[0115] In the preparation step, similarly to the first embodiment, a cavity 12 is formed in the mold 10, a core 20 is placed at a position corresponding to the pressurizing port 16 of the cavity 12, and the mold 10 is clamped. Then, as shown in Fig. 19, the partition 22 is advanced into the cavity 12 to close it, and the main cavity portion 12a and the sub-cavity portion 12b are separated by the partition 22.

[0116] 20, in the next resin introducing step, similar to the first embodiment, molten resin R is introduced from resin injector 50 into cavity 12 via resin supply path 14, and the resin R is spread throughout main cavity portion 12a to fill it. At this time, resin R introduced from gate 14b flows through main cavity portion 12a, but is blocked by partition 22 and does not flow into sub-cavity portion 12b.

[0117] Next, an extrusion step and a flow path opening step are performed together. In the extrusion step and the flow path opening step, as shown in Fig. 21, the partition 22 is retracted into the first storage section 26 to open it, and gas G is injected from the gas injector 60 through the pressure port 16 into the cavity 12 filled with the resin R, as in the first embodiment.

[0118] By doing so, the core 20, which is arranged at one end in the longitudinal direction of the cavity 12 (the end where the pressure port 16 of the main cavity portion 12a is formed), is moved toward the other end in the longitudinal direction of the cavity 12 (the sub-cavity portion 12b side) while extruding the resin R. As a result, a hollow portion 3 is formed in the resin R inside the cavity 12. Furthermore, the core 20 breaks through the resin R in the sub-cavity portion 12b, and the hollow portion 3 formed in the resin R communicates with the discharge flow path 28.

[0119] In the subsequent cooling step, similarly to the first embodiment, gas G is introduced into the hollow portion 3 of the resin R from the pressure port 16 while being discharged from the discharge flow path 28, thereby continuously circulating gas G through the hollow portion 3. This cools the resin R within the cavity 12. The cooling of the resin R is promoted by the flow of gas G through the hollow portion 3. When the resin R is cooled, it solidifies, and a hollow molded article 100 having a hollow portion 3 is molded within the cavity 12.

[0120] In the demolding step that follows, the mold 10 is opened, and the hollow molded article 100 is removed from the open mold 10, in the same manner as in the first embodiment. In the subsequent post-processing step, as shown in Fig. 22, an unnecessary portion 104 is cut and removed from the product portion 102 that forms the tubular body 1 of the hollow molded article 100 that has been removed from the mold 10 at a predetermined position (the position of the cut line Lc shown by the dashed line in Fig. 22; also shown in Fig. 21), in the same manner as in the first embodiment.

[0121] -Features of the fourth embodiment- In the tube molding apparatus 5 of this fourth embodiment, the flow path opening means 32 also connects the hollow portion 3 formed in the resin R in the cavity 12 by the movement of the core 20 with the discharge flow path 28. After the movement of the core 20 is completed in the mold 10, the gas G is introduced from the pressure port 16 while being discharged from the discharge flow path 28, and the gas G is circulated through the hollow portion 3 formed in the resin R in the cavity 12, thereby cooling the resin R. This allows the hollow molded article 100 to be efficiently cooled in the mold 10, and the cooling time of the hollow molded article 100 in the mold 10 can be shortened. In addition, similar effects to those described as features of the first embodiment can be obtained.

[0122] In the tube molding apparatus 5 of this fourth embodiment, the core 20 also serves as the flow path opening means 32. This eliminates the need to provide the mold 10 with a configuration for realizing the flow path opening means 32 separately from the core 20. This allows the number of components of the mold 10 to be reduced, and the cost of the tube molding apparatus 5 to be reduced.

[0123] Fifth Embodiment The tube molding apparatus 5 of this embodiment 5 does not include the partition 22, the first actuator 24, the perforating member 34, and the second actuator 36, and the configuration of the mold 10 differs from that of the above-mentioned embodiment 1. Note that in this embodiment 5, the tube molding apparatus 5 is configured in the same way as in the above-mentioned embodiment 1, except that the configuration of the mold 10 differs from that of the above-mentioned embodiment 1 in that it does not include the partition 22, etc. As such, the details of the same components in the molding apparatus 5 will be omitted and the same description will be omitted.

[0124] -Tube molding equipment- In the tube manufacturing apparatus 5 of this fifth embodiment, the fluid injector 60 also serves as the flow path opening means 32. That is, the flow path opening means 32 is provided separately from the mold 10. As shown in FIG. 23, the sub-cavity portion 12b has an expanded portion 12c. The expanded portion 12c constitutes a portion of the sub-cavity portion 12b closer to the main cavity portion 12a. As shown in FIGS. 24 and 25, the cross-sectional area of ​​the expanded portion 12c in a direction perpendicular to the longitudinal direction of the cavity 12 is larger than the corresponding cross-sectional area of ​​the main cavity portion 12a. The expanded portion 12c in this example is a rectangular parallelepiped space, and its four corners are larger than the main cavity portion 12a.

[0125] The sub-cavity portion 12b further includes a serpentine portion 12d. The serpentine portion 12d is an example of a portion of the cavity 12 located on the opposite side of the pressurization port 16 across the core stopper 45, and constitutes a portion located further back than the enlarged portion 12c of the sub-cavity portion 12b when viewed from the main cavity portion 12a. The serpentine portion 12d is a hollow portion having a serpentine shape. For convenience, in FIG. 23, the serpentine portion 12d is schematically shown as serpentine in the vertical direction of the page. For example, the diameter of the serpentine portion 12d is smaller than the diameter of the main cavity portion 12a. The diameter of the serpentine portion 12d may be equal to or larger than the diameter of the main cavity portion 12a.

[0126] The mold 10 is also provided with a core stopper 45. The core stopper 45 is a protrusion that protrudes inward into the cavity 12 to stop the movement of the core 20. The core stopper 45 is provided in the sub-cavity portion 12b. Specifically, the core stopper 45 is provided in the middle of the expanded portion 12c. That is, the expanded portion 12c is provided so as to include the location where the core 20 stopped by the core stopper 45 is located. It is preferable that the expanded portion 12c include the entire location. The core stopper 45 may be provided at or near the end of the expanded portion 12c on the serpentine portion 12d side.

[0127] The core stopper 45 in this example is formed in a rod shape. The circumferential surface and tip of the core stopper 45 face the inner circumferential surface of the expanded portion 12c with a gap therebetween. The core 20 in this example has a bullet shape. The core 20 may have other shapes, such as a spherical or hemispherical shape. The discharge flow path 28 is connected to a portion located on the far side of the serpentine portion 12d as viewed from the expanded portion 12c. In other words, the discharge flow path 28 opens into a portion of the sub-cavity portion 12b located on the opposite side of the core stopper 45 from the main cavity portion 12a.

[0128] In the expanded portion 12c in a state in which the core 20 is stopped by the core stopper 45, the flow resistance of the resin R is relatively low at the four corners of the expanded portion 12c. Therefore, in the tube molding device 5, when the core 20 is stopped by the core stopper 45 and gas G is further introduced from the pressure port 16, the resin R is extruded and flows from the four corners of the expanded portion 12c, and the introduced gas G flows around the core 20 at the four corners of the expanded portion 12c, forming an internal space S that is connected to the hollow portion 3 on the side of the discharge flow path 28 of the sub-cavity portion 12b relative to the core stopper 45.

[0129] -Tube body manufacturing method- The method for manufacturing the tube 1 of this fifth embodiment also includes a preparation step, a resin introduction step, an extrusion step, a flow path opening step, a cooling step, a demolding step, and a post-treatment step.

[0130] In the preparation step, similar to the first embodiment, a cavity 12 is formed in the mold 10, a core 20 is placed at a position corresponding to the pressurization port 16 of the cavity 12, and the mold 10 is clamped. In the next resin introduction step, as shown in Fig. 26, a predetermined amount of molten resin R is introduced into the cavity 12 from the resin injector 50 via the resin supply path 14, similar to the first embodiment. Subsequently, an extrusion step is started before the resin R reaches the serpentine portion 12d of the cavity 12.

[0131] In the extrusion step, gas G is injected from gas injector 60 via pressure port 16 into cavity 12 into which resin R has been introduced. As a result, as shown in FIG. 27, core 20, which is disposed at one end of cavity 12 in the longitudinal direction (the end where pressure port 16 of main cavity portion 12a is formed), is moved toward the other end of cavity 12 in the longitudinal direction (toward sub-cavity portion 12b) while extruding resin R. Then, core stopper 45 provided on mold 10 stops the movement of core 20. Core 20 moves to expanded portion 12c of sub-cavity portion 12b, and a hollow portion 3 is formed in resin R in cavity 12 as shown in FIG. 29.

[0132] In the next flow path opening step, gas G is continuously injected into cavity 12 from gas injector 60. This extrudes resin R from the four corners of expanded portion 12c, and gas G introduced from pressure port 16 flows through the four corners of expanded portion 12c around core 20 into serpentine portion 12d, as shown in Figures 28 and 30. This forms an internal space S in serpentine portion 12d that is connected to hollow portion 3. Furthermore, the gas G breaks through resin R before reaching the opening of discharge flow path 28 in serpentine portion 12d, connecting hollow portion 3 formed in resin R to discharge flow path 28.

[0133] In the subsequent cooling step, similarly to the first embodiment, gas G is introduced into the hollow portion 3 of the resin R from the pressure port 16 while being discharged from the discharge flow path 28, thereby continuously circulating gas G through the hollow portion 3. This cools the resin R within the cavity 12. The cooling of the resin R is promoted by the flow of gas G through the hollow portion 3. When the resin R is cooled, it solidifies, and a hollow molded article 100 having a hollow portion 3 is molded within the cavity 12.

[0134] In the demolding step that follows, similarly to the first embodiment, the mold 10 is opened and the hollow molded article 100 is removed from the open mold 10. In the post-processing step that follows, similarly to the first embodiment, the unnecessary portion 104 is cut and removed from the product portion 102 that forms the tubular body 1 of the hollow molded article 100 that has been removed from the mold 10 at a predetermined position (a position corresponding to the cut line Lc shown by the dashed dotted line in FIG. 28).

[0135] -Features of the fifth embodiment- In the tube molding apparatus 5 of this fifth embodiment, the flow path opening means 32 also connects the hollow portion 3 formed in the resin R in the cavity 12 by the movement of the core 20 with the discharge flow path 28. After the movement of the core 20 is completed in the mold 10, the gas G is introduced from the pressure port 16 while being discharged from the discharge flow path 28, and the gas G is circulated through the hollow portion 3 formed in the resin R in the cavity 12, thereby cooling the resin R. This allows the hollow molded article 100 to be efficiently cooled in the mold 10, and the cooling time of the hollow molded article 100 in the mold 10 can be shortened. In addition, similar effects to those described as features of the first embodiment can be obtained.

[0136] In the tube molding apparatus 5 of this fifth embodiment, a core stopper 45 is provided on the mold 10, and the core stopper 45 stops the movement of the core 20. The core 20 whose movement is stopped by the core stopper 45 remains inside the hollow molded product 100 having the hollow portion 3 molded in the cavity 12. Therefore, the core 20 can be relatively easily recovered.

[0137] In the tube molding apparatus 5 of this fifth embodiment, an expanded portion 12c is provided in the sub-cavity portion 12b of the cavity 12, which molds the unnecessary portion 104 of the hollow molded product 100, at a location where the core 20 stopped by the core stopper 45 is located. The cross-sectional area of ​​the expanded portion 12c is larger than the cross-sectional area of ​​the main cavity portion 12a of the cavity 12, which molds the product portion 102 of the hollow molded product 100. This facilitates the flow of resin R around the core 20 in the longitudinal direction of the cavity 12. Gas G introduced from the pressure port 16 flows around the core 20 in the expanded portion 12c and forms an internal space S in the serpentine portion 12d that is connected to the hollow portion 3. This allows a structure in which gas G introduced from the pressure port 16 is distributed throughout the serpentine portion 12d and discharged from the discharge flow path 28 to be realized relatively easily.

[0138] In the tube molding apparatus 5 of this fifth embodiment, the fluid injector 60 also serves as the flow path opening means 32. This eliminates the need to provide a component for realizing the flow path opening means 32 separately from the fluid injector 60, for example by providing the component in the mold 10. This simplifies the structure of the mold 10 and reduces the number of components in the tube molding apparatus 5. As a result, the cost of the tube molding apparatus 5 can be reduced.

[0139] In the manufacturing method of the tube 1 of this fifth embodiment, the movement of the core 20 is stopped by a core stopper 45 provided in the mold 10. The core 20 whose movement is stopped by the core stopper 45 remains inside the hollow molded product 100 having the hollow portion 3 molded in the cavity 12. Therefore, the core 20 can be relatively easily recovered.

[0140] In the manufacturing method of the tubular body 1 of this fifth embodiment, the gas G introduced from the pressure port 16 flows around the core 20 stopped by the core stopper 45, through the core stopper 45, into the serpentine portion 12d of the cavity 12 located on the opposite side from the pressure port 16, and is then discharged from the discharge flow path 28 through the internal space S formed in the serpentine portion 12d. This allows the main cavity 12a to be made longer than when the discharge flow path 28 opens closer to the main cavity 12a than the core stopper 45. This is advantageous for making the mold 10 more compact.

[0141] In the manufacturing method of the tubular body 1 of this fifth embodiment, in the flow path opening step, the resin R is broken by the gas G introduced from the pressure port 16, thereby connecting the hollow portion 3 and the discharge flow path 28. This eliminates the need to provide a separate component for connecting the hollow portion 3 and the discharge flow path 28 to the mold 10, for example. This simplifies the structure of the mold 10 and reduces the number of components in the molding apparatus 5 for the tubular body. As a result, the cost of the molding apparatus 5 for the tubular body can be reduced.

[0142] -Modification of the fifth embodiment- As shown in Figures 31 and 32, the expanded portion 12c of the cavity 12 is a keyhole-shaped space with a rectangle attached to the outer periphery of a circle, and may be larger than the main cavity portion 12a in part of its circumferential direction.

[0143] 33 and 34, in the flow path opening step in the manufacture of the tubular body 1, gas G is injected from a gas injector 60 into the cavity 12, forcing the resin R out of the rectangular portion protruding toward the outer periphery of the expanded portion 12c, causing the gas G to bypass the periphery of the core 20 at the rectangular portion of the expanded portion 12c and flow into the serpentine portion 12d. As a result, an internal space S connected to the hollow portion 3 is formed in the serpentine portion 12d, and the gas G breaks the resin R, connecting the hollow portion 3 formed in the resin R to the discharge flow path 28.

[0144] The tube forming apparatus 5 and the method for manufacturing the tube 1 of this modified example can also provide the same effects as those described as features of the fifth embodiment.

[0145] As described above, preferred embodiments have been described as examples of the technology of the present disclosure. However, the technology of the present disclosure is not limited to these, and can be applied to embodiments in which appropriate modifications, substitutions, additions, omissions, etc. are made. It will be understood by those skilled in the art that various modifications are possible to the above-described embodiments without departing from the spirit of the technology of the present disclosure, and that such modifications also fall within the scope of the technology of the present disclosure.

[0146] For example, in the above-mentioned Embodiments 1 to 4, the piercing member 34 is described as having a sharp tip, but this is not limited thereto. If the piercing member 34 is advanced while there are uncured portions in the unnecessary portion 104 of the hollow molded article 100 in the sub-cavity portion 12b, the tip of the piercing member 34 does not need to be sharp. As long as the piercing member 34 can advance into the cavity 12 to form an open hole 106 in the wall of the resin R that forms the unnecessary portion 104 of the hollow molded article 100, various shapes can be adopted for the piercing member 34.

[0147] In addition, in the above-described first to fifth embodiments, nitrogen gas is used as the gas G as the pressurized fluid, but this is not limiting. Nitrogen gas is merely one example of the pressurized fluid, and an inert gas other than nitrogen gas, such as argon, or other types of gas may be used as long as it does not react with the resin R at the temperature and pressure when passing through the core 20. Furthermore, liquids such as water and glycerin may also be used as the pressurized fluid.

[0148] Furthermore, in the fifth embodiment, the tube forming apparatus 5 does not include the partition 22, the first actuator 24, the perforating member 34, and the second actuator 36, but this is not limited to this. As shown in Fig. 35, the tube forming apparatus 5 of the fifth embodiment may also include the partition 22, the first actuator 24, the perforating member 34, and the second actuator 36, and the first actuator 24 and the second actuator 36 may be operated in the same manner as in the first embodiment, etc.

[0149] In addition, in the fifth embodiment, the expanded portion 12c of the cavity 12 is a rectangular parallelepiped space, but this is not limiting. The expanded portion 12c may be a space of another shape, such as a triangular prism, as long as the flow resistance of the fluid is relatively reduced around the core 20 stopped by the core stopper 45, making it easier for the molten resin R to flow.

[0150] It should be noted that the terms "first," "second," etc. mentioned above are used merely to distinguish the terms to which these terms are attached, and do not limit the number or order of the terms. [Industrial Applicability]

[0151] INDUSTRIAL APPLICABILITY As described above, the present disclosure is useful for a tube molding apparatus and a tube manufacturing method using the same. [Explanation of symbols]

[0152] G Gas (pressurized fluid) R resin S interior space 1. Body 3 Hollow part 5. Tube molding device 10. Mold 12 cavities 12a Main cavity part 12b Sub-cavity part 12c Enlarged section 14 Resin supply path Gate 14a 16 Pressure Port 20 cores 26 First storage section (storage section) 28 Discharge flow path 32 Flow path opening means 34 Perforated member 36 Second actuator (actuator) 38 Second storage section (storage section) 42 Haunting Hole 44 Third Actuator (Actuator) 45 Core stopper 50 resin injection machine 60 Gas Injector (Fluid Injector) 100 Hollow molded products 102 Product part 104 Unnecessary part 106 Opening

Claims

1. An apparatus for molding a resin pipe (1), a mold (10) having a cavity (12) for molding the pipe body (1); a resin injector (50) that injects molten resin (R) into the cavity (12); a fluid injector (60) for injecting a pressurized fluid (G) into the cavity (12); The mold (10) includes: a resin supply path (14) for introducing the resin (R) sent from the resin injector (50) into the cavity (12); a pressure port (16) that opens at one end of the cavity (12) in the longitudinal direction and introduces a pressurized fluid (G) sent from the fluid injector (60) into the cavity (12); a core (20) that is disposed in the cavity (12) at a position corresponding to the opening of the pressurized port (16), and that moves inside the resin (R) introduced into the cavity (12) toward the other end in the longitudinal direction of the cavity (12) by the pressure of the pressurized fluid (G) introduced from the pressurized port (16); a discharge flow path (28) that opens to the other end of the cavity (12) in the longitudinal direction and discharges the pressurized fluid (G) in the cavity (12) to the outside; a flow path opening means (32) for connecting a hollow portion (3) formed in the resin (R) by movement of the core (20) to the discharge flow path (28), After the movement of the core (20) in the mold (10) is completed, the pressurized fluid (G) is introduced from the pressurized port (16) while being discharged from the discharge flow path (28), and the pressurized fluid (G) is circulated through the hollow portion (3), thereby cooling the resin (R). A tube forming apparatus characterized by:

2. The tube forming apparatus according to claim 1, The hollow molded product (100) having the hollow portion (3) molded in the cavity (12) includes a product portion (102) forming the tubular body (1) and an unnecessary portion (104) other than the product portion (102), The flow path opening means (32) forms an opening (106) in the unnecessary portion (104) of the hollow molded product (100) to communicate the hollow portion (3) with the discharge flow path (28). A tube forming apparatus characterized by:

3. The tube forming apparatus according to claim 1, The mold (10) is provided with a storage section (38) having an outlet (42) that opens to the outer peripheral surface of the cavity (12), The flow path opening means (32) a piercing member (34) accommodated in the accommodation portion (38); an actuator (36) that displaces the piercing member (34) between an advanced position where the piercing member (34) is advanced into the cavity (12) from the inlet / outlet (42) and a retracted position where the piercing member (34) is retracted to a position deeper than the inlet / outlet (42) of the storage section (38), When the piercing member (34) is in the retracted position, a portion of the accommodation portion (38) between the piercing member (34) and the outlet (42) forms a part of the discharge flow path (28). A tube forming apparatus characterized by:

4. The tube forming apparatus according to claim 1, The mold (10) is further provided with a partition (22) that divides the cavity (12) into a main cavity portion (12a) and a sub-cavity portion (12b), the partition (22) is switchable between a closed state in which the partition (22) closes the gap between the main cavity portion (12a) and the sub-cavity portion (12b) and an open state in which the partition (22) communicates with the main cavity portion (12a) and the sub-cavity portion (12b), The main cavity portion (12a) is provided with a gate (14b) forming the resin supply passage (14) and a pressure port (16), With the partition (22) in the closed state to partition the cavity (12), the molten resin (R) is introduced through the gate (14b) into the main cavity portion (12a) to fill it, and then the partition (22) is opened and a pressurized fluid (G) is injected through the pressure port (16) to move the core (20) into the sub-cavity portion (12b). A tube forming apparatus characterized by:

5. The tube forming apparatus according to claim 4, The mold (10) is provided with a storage section (26) having an outlet (42) that opens to the outer peripheral surface of the cavity (12), The flow path opening means (32) a piercing member (34) accommodated in the accommodation portion (26); an actuator (44) that displaces the piercing member (34) between an advanced position where the piercing member (34) is advanced from the inlet (42) into the cavity (12) and a retracted position where the piercing member (34) is retracted to a position deeper than the inlet (42) of the storage section (26), When the piercing member (34) is in the retracted position, a portion of the accommodation portion (26) between the piercing member (34) and the outlet (42) forms a part of the discharge flow path (28), The perforating member (34) is provided in combination with the partition body (22). A tube forming apparatus characterized by:

6. The tube forming apparatus according to claim 1, The core (20) also serves as the flow path opening means (32). A tube forming apparatus characterized by:

7. The tube forming apparatus according to claim 1, The die (10) is provided with a core stopper (45) that stops the movement of the core (20). A tube forming apparatus characterized by:

8. The tube forming apparatus according to claim 7, The cavity (12) includes a main cavity portion (12a) for molding a product portion (102) constituting the tubular body (1) of a hollow molded product (100) having the hollow portion (3) molded in the cavity (12), and a sub-cavity portion (12b) for molding an unnecessary portion (104) of the hollow molded product (100) other than the product portion (102), the core stopper (45) is provided in the sub-cavity portion (12b), the discharge flow path (28) opens into a portion of the sub-cavity (12b) that is located on the opposite side of the core stopper (45) from the main cavity (12a); the sub-cavity portion (12b) has an enlarged portion (12c) at a position where the core (20) stopped by the core stopper (45) is located, the enlarged portion (12c) having a cross-sectional area in a direction perpendicular to the longitudinal direction of the cavity (12) larger than that of the main cavity portion (12a); After the core (20) is stopped by the core stopper (45), the pressurized fluid (G) introduced from the pressurized port (16) flows around the core (20) in the expanded portion (12c) and forms an internal space (S) connected to the hollow portion (3) on the side of the sub-cavity portion (12b) closer to the discharge flow path (28) than the core stopper (45). A tube forming apparatus characterized by:

9. The tube forming apparatus according to claim 8, The fluid injector (60) also serves as the flow path opening means (32). A tube forming apparatus characterized by:

10. The tube forming apparatus according to claim 1, The pressurized fluid (G) is a gas (G); A tube forming apparatus characterized by:

11. A method for manufacturing the tube body (1) using the tube body forming apparatus (5) according to any one of claims 1 to 10, comprising: a resin introducing step of introducing the molten resin (R) from the resin injector (50) into the cavity (12) via the resin supply path (14) while the core (20) is disposed at a position corresponding to the pressurization port (16) of the cavity (12); an extrusion step of injecting a pressurized fluid (G) from the fluid injector (60) through the pressurized port (16) into the cavity (12) into which the resin (R) has been introduced, thereby moving the core (20) disposed at one end of the cavity (12) in the longitudinal direction toward the other end of the cavity (12) in the longitudinal direction while extruding the resin (R); a flow path opening step of connecting a hollow portion (3) formed in the resin (R) by the movement of the core (20) with the discharge flow path (28); a cooling step in which, after the movement of the core (20) in the mold (10) is completed, a pressurized fluid (G) is introduced from the pressurization port (16) while being discharged from the discharge flow path (28) to circulate the pressurized fluid (G) through the hollow portion (3), thereby cooling the resin (R); a demolding step of removing a hollow molded product (100) having the hollow portion (3) molded in the cavity (12) from the mold (10); and a post-processing step of removing unnecessary portions (104) of the hollow molded product (100) removed from the mold (10) other than the product portion (102) forming the tubular body (1). A method for manufacturing a tube body, comprising:

12. The method for manufacturing a tube according to claim 11, In the extrusion step, the movement of the core (20) is stopped by a core stopper (45) provided in the die (10). A method for manufacturing a tube body, comprising:

13. The method for manufacturing a tube according to claim 12, In the cooling step, the pressurized fluid (G) introduced from the pressurized port (16) is passed around the core (20) stopped by the core stopper (45) and flows through the core stopper (45) to a portion of the cavity (12) located on the opposite side of the pressurized port (16), thereby forming an internal space (S) connected to the hollow portion (3) in that portion, and the pressurized fluid (G) that has flowed through the internal space (S) is discharged from the discharge flow path (28). A method for manufacturing a tube body, comprising:

14. The method for manufacturing a tube according to claim 13, In the flow path opening step, the resin (R) is broken by the pressurized fluid (G) introduced from the pressurized port (16), thereby connecting the hollow portion (3) and the discharge flow path (28). A method for manufacturing a tube body, comprising:

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