Manufacturing methods for piping structures, molds, and pipe fittings

Abstract

To provide a piping structure that is less likely to affect the sealing function between the tube and the sealing member. [Solution] The piping structure includes a pipe fitting having a tube connection portion with an annular groove formed therein, a sealing member provided in the annular groove, and a tube connected to the tube connection portion with the sealing member provided in the annular groove, wherein the tube connection portion has a through hole penetrating the groove wall of the annular groove, or a notch formed by partially cutting out the outer surface of the groove wall of the annular groove, and the through hole or the notch functions as a gate for injection molding the sealing member.

Description

Technical Field

[0001] The present disclosure relates to a manufacturing method of a piping structure, a mold, and a pipe fitting.

Background Art

[0002] Patent Document 1 discloses an O-ring formed by using a component to which an O-ring is to be attached as an inner mold for O-ring molding as it is, covering it with a half outer mold, and injecting a rubber material through a rubber material injection hole.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, since the gate for forming the seal member is provided on the seal surface which is the outer peripheral surface of the seal member, gate marks are generated on the seal surface, which affects the sealing function between the tube connected to the tube connection portion of the pipe fitting and the seal member.

[0005] The present disclosure provides a piping structure that is less likely to affect the sealing function between the tube connected to the tube connection portion of the pipe fitting and the seal member.

Means for Solving the Problems

[0006] A piping structure according to a first aspect of the present disclosure includes a pipe fitting having a tube connection portion having an annular groove, a sealing member provided in the annular groove, and a tube connected to the tube connection portion with the sealing member provided in the annular groove, wherein the tube connection portion has a through hole penetrating the groove wall of the annular groove, or a notch formed by partially cutting out the outer surface of the groove wall of the annular groove, and the through hole or the notch functions as a gate for injection molding the sealing member.

[0007] In the piping structure of the first embodiment, the gate, which is formed by injecting resin into the annular groove of the tube connection portion to form the sealing member, is provided in a location other than the sealing surface, which is the outer surface of the sealing member. Therefore, unlike in the conventional method, no gate marks are generated on the sealing surface. As a result, the sealing function between the tube and the sealing member is less likely to be affected.

[0008] Furthermore, since the sealing member is provided in the annular groove of the tube connection by injection molding, the process of assembling the sealing member into the annular groove is eliminated.

[0009] The piping structure of the second embodiment is the piping structure of the first embodiment, wherein the tube connection portion has a retaining portion that slopes radially outward from the tip side to the base end side of the pipe joint, and the through hole is inclined in the direction in which the retaining portion slopes.

[0010] In the piping structure of the second embodiment, the die-cutting process becomes easier compared to a configuration in which the through-hole is inclined in a direction different from the direction in which the retaining portion is inclined.

[0011] The third embodiment of the piping structure is the piping structure of the first embodiment or the second embodiment, wherein the sealing member is provided along one groove wall of the annular groove, and the through hole or notch is formed in the one groove wall.

[0012] In the third embodiment of the piping structure, the resin injected through the through hole or notch forms a sealing member along one groove wall, so the amount of resin that forms the sealing member can be reduced compared to a configuration in which the resin is injected along the other groove wall.

[0013] The fourth embodiment of the piping structure is the same as the third embodiment, wherein the sealing member is provided at a distance from the other groove wall of the annular groove.

[0014] In the piping structure of the fourth embodiment, when the tube is connected to the tube connection, the degree of freedom of deformation of the sealing member can be increased compared to a configuration in which the sealing member is provided along the other groove wall of the annular groove.

[0015] The fifth piping structure is any one of the first to fifth embodiments, wherein the through hole is formed radially inward from the outer edge of the groove wall in the annular groove.

[0016] According to the fifth embodiment of the piping structure, the strength of the groove wall in which the through-hole serving as a gate is formed can be maintained.

[0017] The mold of the sixth embodiment is an injection molding mold for forming a pipe joint in a piping structure that includes a pipe joint having a tube connection portion with an annular groove formed therein and a sealing member provided in the annular groove, wherein the portion that forms the tube connection portion is provided with a slidable die portion having a hole-punching portion that forms a through hole penetrating the groove wall of the annular groove, or a protrusion that forms a notch that partially cuts out the outer circumferential surface of the groove wall of the annular groove.

[0018] The mold of the sixth embodiment provides a mold for a pipe fitting in which no gate marks are generated on the sealing surface.

[0019] The mold of the seventh embodiment is the mold of the sixth embodiment, wherein the punching portion extends in one direction, and the sliding direction of the die portion is the same as the direction in which the punching portion extends.

[0020] In the mold of the seventh embodiment, the punching portion forms a through hole in accordance with the sliding of the die portion, making it easier to form the through hole compared to a configuration in which the sliding of the die portion and the formation of the through hole by the punching portion are unrelated.

[0021] The manufacturing method of the pipe joint according to the eighth aspect is a method for manufacturing a pipe joint in which a seal member is provided in an annular groove formed on the outer peripheral surface of a resin tube connection part, and the tube is connected to the tube connection part. In a state where a gate for injection molding the seal member is partitioned from the groove wall of the annular groove, a first resin is injected into the cavity of the first mold to form the tube connection part. And a step of forming the seal member by injecting a second resin through the gate into a cavity formed by the second mold and the tube connection part with the second mold disposed on the outer peripheral side of the tube connection part after removing the first mold.

[0022] In the manufacturing method of the pipe joint according to the eighth aspect, a pipe joint in which gate marks do not occur on the seal surface can be manufactured.

[0023] The manufacturing method of the pipe joint according to the ninth aspect is the manufacturing method of the pipe joint according to the eighth aspect, wherein the gate is partitioned as a hole punching part that becomes a through hole in the groove wall of the annular groove, or a convex part that becomes a notch part obtained by cutting a part of the outer peripheral surface of the groove wall of the annular groove.

[0024] In the manufacturing method of the pipe joint according to the ninth aspect, a gate can be formed with a simple configuration.

Advantages of the Invention

[0025] According to the present disclosure, a piping structure that is unlikely to affect the sealing function between the tube connected to the tube connection part of the pipe joint and the seal member can be provided.

Brief Description of the Drawings

[0026] [Figure 1] It is a partial cross-sectional view showing a state where a tube is connected to a tube connection part of a pipe joint according to the piping structure of the present embodiment. [Figure 2] It is a cross-sectional view showing a pipe joint in a state where a seal member is provided in the annular groove of the present embodiment. [Figure 3] It is a cross-sectional view taken along line S1 - S1 of FIG. 2. [Figure 4] It is a cross-sectional view of the mold of the present embodiment. [Figure 5] This is a cross-sectional view taken along the line S2-S2 in Figure 4. [Figure 6] This is a cross-sectional view showing the state in which a pipe joint has been formed using the mold of this embodiment. [Figure 7] This is a cross-sectional view showing the state after the first mold has been removed from the mold of this embodiment. [Figure 8] This is a cross-sectional view showing the second mold attached to the mold of this embodiment. [Figure 9] Figure 8 is a cross-sectional view showing the state in which the second resin, which will serve as the sealing member, has been filled into the second cavity from the gate of the second mold. [Figure 10] This is a cross-sectional view showing a modified example of the pipe joint in which a sealing member is provided in the annular groove of this embodiment. [Figure 11] This is a cross-sectional view of the line S3-S3 in Figure 10. [Figure 12] This is a cross-sectional view of a modified example of the mold of this embodiment. [Figure 13] This is a cross-sectional view showing a modified example of the mold of this embodiment, in which a second mold is attached to the outer circumference of the tube connection portion. [Modes for carrying out the invention]

[0027] Hereinafter, embodiments for implementing this disclosure (this embodiment) will be described with reference to the drawings. Components indicated by the same reference numerals in each drawing are the same or similar components. In the embodiments described below, descriptions and reference numerals that are repeated may be omitted. Furthermore, the drawings used in the following description are all schematic, and the dimensional relationships and ratios of each element shown in the drawings do not necessarily correspond to reality. Also, the dimensional relationships and ratios of each element do not necessarily correspond between multiple drawings.

[0028] An example of the piping structure of this embodiment will be described with reference to the drawings.

[0029] <Piping structure configuration> The piping structure 10 of this embodiment will now be described. As shown in Figure 1, the piping structure 10 includes a pipe fitting 20, a sealing member 30, and a tube 12, and the tube 12 is connected to the pipe fitting 20 via the sealing member 30. In the piping structure 10, the tube 12 is connected to the tube connection portion 14 of the pipe fitting 20 by press-fitting with the sealing member 30 provided in the annular groove 26, and the sealing member 30 seals the inside of the tube 12 and the outside of the tube connection portion 14. Details will be described later. A medium, such as a coolant, is passed through the inside of the piping structure 10.

[0030] Furthermore, the medium passed through the piping structure 10 is not limited to a fluid containing a coolant. For example, the medium may be a powder, granules, etc. Also, the fluid is not limited to a coolant. For example, it may be fuel, oil, water or other liquids, or a gas.

[0031] Tube 12 is a resin cylinder that extends in the axial direction.

[0032] (Pipe fittings) The pipe fitting 20 is a resin pipe connected to the tube 12. The outer diameter of the pipe fitting 20 is formed to be slightly larger than the inner diameter of the tube 12. The pipe fitting 20 has a base (not shown) and one or more tube connection parts 14.

[0033] The base is the main body portion of the pipe joint 20. A space (not shown) is formed inside the base. The base can take on shapes such as a straight line, T-shape, or L-shape from its external appearance.

[0034] The tube connection portion 14 is configured on the end side of the pipe joint 20 and is, for example, cylindrical in shape that extends in the axial direction.

[0035] Furthermore, if the pipe fitting 20 includes multiple tube connections, not all tube connections are limited to extending in the axial direction. For example, other tube connections may extend in a direction intersecting the axial direction of one tube connection. In this case, the direction intersecting the axial direction is, for example, the radial direction of the tube connection 14.

[0036] A medium (not shown) moves between the inside of the tube connector 14 and the inside of the base. In this embodiment, the tube connector 14 is formed integrally with the base. The tube connector 14 is connected to the tube 12. Specifically, the tube connector 14 is connected by press-fitting it into the end (not shown) of the tube 12. The tube connector 14 has a tip portion 22, a groove wall 24, an annular groove 26, and a retaining portion 28 formed on the cylindrical body portion 16.

[0037] The tip portion 22 is formed on the open end side of the tube connection portion 14 and is a tapered portion formed radially outward from the outer circumferential surface 16A of the main body portion 16. Specifically, the tip portion 22 is radially widened outward toward the base of the pipe fitting 20. The tip portion 22 widens the end of the tube 12 to be connected. The tip portion 22 is an example of the tip of a pipe fitting. The base is an example of the base end side of a pipe fitting.

[0038] The groove wall 24 is formed in an annular shape around the axis CN, rising radially from the outer circumferential surface 16A of the main body 16. The groove wall 24 is positioned axially away from the tip portion 22 and closer to the base than the tip portion 22. The radially outer end of the groove wall 24 contacts the inner circumferential surface of the tube 12 when the tube 12 is connected to the tube connection portion 14. Details of the groove wall 24 will be described later.

[0039] The annular groove 26 is an annular groove with the outer circumferential surface 16A of the main body portion 16 as the groove bottom. In the annular groove 26, one of the walls constituting the groove is the groove wall 24, and the other of the wall is the tip portion 22. In other words, the annular groove 26 is a region demarcated by the outer circumferential surface 16A and the tip portion 22 and groove wall 24 in the axial direction.

[0040] The retaining portion 28 is a return that is formed in an annular shape around the axis CN, rising radially from the outer circumferential surface 16A of the main body portion 16. The retaining portion 28 is inclined radially outward from the tip portion 22 toward the base portion. The retaining portion 28 contacts the inner circumferential surface of the tube 12, stopping the axial movement of the tube 12 that is attempting to detach from the tube connection portion 14. One or more retaining portions 28 are formed. In this embodiment, two retaining portions 28 are formed axially separated from the groove wall 24, and are located closer to the base portion than the groove wall 24.

[0041] As a result, the pipe joint 20 is formed.

[0042] (Sealing material) The sealing member 30 is an elastic resin member formed in an annular shape around the axis CN. The sealing member 30 is provided in the annular groove 26. Specifically, the sealing member 30 is provided along the groove wall 24. The elastic modulus of the sealing member 30 is set to be greater than that of the pipe fitting 20. The sealing member 30 fills the radial gap between the pipe fitting 20 and the tube 12 by elastically deforming when the tube 12 is connected to the tube connection portion 14. In other words, in the sealing member 30, the radially outer end face 30A contacts the inner circumferential surface of the tube 12, and this end face acts as a sealing surface.

[0043] As shown in Figure 2, when the tube 12 is not connected to the tube connection 14, the end face 30A of the sealing member 30 is located radially outward from the radially outward end face of the groove wall 24, compared to when the tube 12 is connected to the tube connection 14. The formation of the sealing member 30 will be described later.

[0044] (Summary of key points) Next, the main parts of the piping structure 10 will be described.

[0045] In the piping structure 10 when the tube 12 is not connected, that is, in the pipe joint 20 when the sealing member 30 is provided in the annular groove 26, as shown in Figure 2, the sealing member 30 is positioned so that it is in contact with the groove wall 24 inside the annular groove 26 in the axial direction, and a gap G is formed between the tip portion 22 and the sealing member 30 in the axial direction. In other words, the sealing member 30 is provided at a distance from the tip portion 22.

[0046] As shown in Figures 2 and 3, a through-hole 32 is formed in the groove wall 24, penetrating the groove wall 24. The through-hole 32 is also inclined in the direction in which the retaining portion 28 is inclined. Specifically, the through-hole 32 is formed in the groove wall 24, extending diagonally outward from the tip portion 22 toward the base portion of the pipe joint 20. More specifically, the through-hole 32 is formed diagonally from a position radially inward of the radially outer end of the groove wall 24 on the axial base-side surface of the groove wall 24 toward the groove bottom of the annular groove 26 on the axial tip portion 22-side surface of the groove wall 24. The radially outer end is an example of an outer edge.

[0047] Furthermore, the through-hole 32 is not limited to being inclined. For example, the through-hole 32 may be formed along the axis CN, and in particular, it may be formed continuously from the bottom of the annular groove 26 (i.e., at the same level as the bottom of the groove).

[0048] The second resin, which is the material for the sealing member 30, remains inside the through-hole 32. One through-hole 32 is formed in the groove wall 24. The through-hole 32 functions as a gate for injection molding the sealing member 30.

[0049] <Mold configuration> Next, an example of a mold 40 for two-color molding of the pipe fitting 20 and the sealing member 30 will be described. The mold 40 is an injection molding mold for molding the pipe fitting 20 in the piping structure 10.

[0050] As shown in Figure 4, the mold 40 of this embodiment has multiple molds and is used for two-color molding. Two-color molding is an example of injection molding. Specifically, the mold 40 comprises a main body 42, a first mold 44, and a second mold 50. The main body 42 and the first mold 44 are examples of parts that form a tube connection.

[0051] The main body portion 42 is a mold used for both primary and secondary molding in two-color molding. In this embodiment, the main body portion 42 divides the inside of the main body portion 16 and the portion that will become the tip portion 22 of the tube connection portion 14.

[0052] (First mold) The first mold 44 is used for primary molding and is a mold for forming the pipe joint 20. The first mold 44, together with the main body 42, constitutes the first cavity C1 which becomes the pipe joint 20. The first cavity C1 is an example of a cavity in the first mold. The first mold 44 forms the pipe joint 20 by filling the first cavity C1 with molten first resin through a runner and a gate (neither of which are shown in the figure). The first mold 44 has a first die portion 46 and a second die portion 48.

[0053] The first die portion 46 demarcates the groove wall 24, a part of the annular groove 26, and a part of the retaining portion 28. As shown in Figure 5, the first die portion 46 is divisible into two parts in a direction intersecting the axial direction (left-right direction in Figure 5) and is a mold that can be removed from the main body portion 42.

[0054] As shown in Figure 4, the second piece portion 48 demarcates the through hole 32, the other part of the annular groove 26, and the other part of the retaining portion 28. The second piece portion 48 is removable from the main body portion 42 and is a mold that can slide in a sliding direction X (see Figure 6) inclined with respect to the axis CN. The second piece portion 48 is positioned in a state of engagement with axially separated portions of the first piece portion 46. The second piece portion 48 is an example of a piece portion. The second piece portion 48 has a hole-punching portion 34.

[0055] The perforated portion 34 extends in the sliding direction X (see Figure 6) and forms a through hole 32 that penetrates the groove wall 24 of the annular groove 26. The perforated portion 34 is an example of a gate. The sliding direction X is an example of a unidirectional direction. The perforated portion 34 is formed, for example, in the shape of a rod. The perforated portion 34 is inclined radially inward from the main body portion of the second piece portion 48 toward the first piece portion 46.

[0056] (Second mold) As shown in Figure 8, the second mold 50 is used for secondary molding and is a mold for forming the sealing member 30. The second mold 50 has a small piece portion 58. The small piece portion 58 forms the gap G formed between the tip portion 22 of the pipe joint 20 and the sealing member 30.

[0057] The second mold 50, together with the pipe fitting 20 formed by primary molding, constitutes a second cavity C2 which becomes a sealing member 30. The second cavity C2 is an example of a cavity composed of the second mold and the pipe fitting. The second mold 50 forms the sealing member 30 when the molten second resin fills the second cavity C2 through the runner 54, gate 56, through hole 32 and small piece portion 58 (see Figure 9).

[0058] The second mold 50 is divisible into two parts (not shown) similar to the first piece portion 46 shown in Figure 5, and is a mold that can be removed from the main body portion 42. In this embodiment, a gate 56 leading to the through hole 32 is formed only in the rear portion of the cross-section of the second mold 50, and no gate 56 is formed in the front portion of the cross-section (not shown).

[0059] <Method for manufacturing pipe fittings> Next, a method for manufacturing pipe fittings will be described. The method for manufacturing pipe fittings includes the steps of forming a pipe fitting 20 and forming a sealing member 30.

[0060] (Primary molding) The primary molding process, which forms the pipe joint 20, will now be described. As shown in Figure 4, the main body 42 and the first mold are prepared from the mold 40.

[0061] With the hole-punching portion 34 of the second piece portion 48 demarcated as a gate for injection molding the sealing member 30, the molten first resin, which will become the pipe joint 20, is injected into the first cavity C1. As shown in Figure 6, the pipe joint 20 is formed by filling the first cavity C1 (see Figure 4) with the first resin.

[0062] When the first mold 44 is removed from the pipe fitting 20 and the main body 42, the state shown in Figure 7 is obtained. During removal, the first piece 46 is removed in the direction shown in Figure 5, and then the second piece 48 is slid in the sliding direction X shown in Figure 6.

[0063] (Secondary molding) Secondary molding, which is the process of forming the sealing member 30, will now be described. As shown in Figure 8, the second mold 50 is placed on the pipe joint 20 and the main body 42 after the first mold 44 has been removed.

[0064] The molten second resin, which will become the sealing member 30, is injected into the second cavity C2 through the gate 56. As shown in Figure 9, the runner 54, gate 56, through hole 32, and second cavity C2 are filled with the second resin.

[0065] Once the molten second resin has solidified, the second mold 50 is divided into a front side and a back side in cross-section. During this division, the second resin solidified inside the gate 56 is held in the second mold 50, and the second resin solidified inside the through hole 32 is held in the groove wall 24, resulting in a gate mark on the axial base side surface of the groove wall 24.

[0066] When the main body 42 is removed from the pipe joint 20, the pipe joint 20 and the sealing member 30 are formed as shown in Figure 2.

[0067] Based on the above, the pipe fitting 20 is manufactured.

[0068] <Effects and Effects> The effects and advantages of this embodiment will now be explained.

[0069] The piping structure 10 of this embodiment includes a pipe joint 20 having a tube connection portion 14 with an annular groove 26 formed therein, a sealing member 30 provided in the annular groove 26, and a tube 12 connected to the tube connection portion 14 by press-fitting with the sealing member 30 provided in the annular groove 26. In this piping structure 10, a through hole 32 is formed in the tube connection portion 14, penetrating the groove wall 24 of the annular groove 26, and the through hole 32 functions as a gate 56 for injection molding the sealing member 30.

[0070] According to this configuration, the gate 56, which forms the sealing member 30 by injecting the second resin into the annular groove 26, is provided at a location other than the radially outer end face 30A of the sealing member 30, which is the sealing surface. Therefore, unlike in the conventional method, no gate marks are generated on the sealing surface. As a result, the sealing function between the tube 12 and the sealing member 30 is less affected.

[0071] Furthermore, since the sealing member 30 is provided in the annular groove 26 by injection molding of the second resin, the process of assembling an O-ring into the annular groove 26 is eliminated.

[0072] Furthermore, in the piping structure 10 of this embodiment, the tube connection portion 14 has a retaining portion 28 that slopes radially outward from the tip portion 22 of the pipe joint 20 toward the base, and the through hole 32 is inclined in the direction in which the retaining portion 28 slopes.

[0073] This configuration makes it easier to remove the molded parts compared to a configuration in which the through-hole is inclined in a direction different from the direction in which the retaining portion 28 is inclined.

[0074] Furthermore, in the piping structure 10 of this embodiment, the sealing member 30 is provided along the groove wall 24, and the through hole 32 is formed in the groove wall 24.

[0075] With this configuration, the second resin injected from the through hole 32 forms a sealing member 30 along the groove wall 24, so the amount of the second resin that forms the sealing member 30 can be reduced compared to a configuration in which the resin is injected along the tip portion 22 of the pipe joint 20.

[0076] Furthermore, in the piping structure 10 of this embodiment, the sealing member 30 is provided at a distance from the tip portion 22 of the pipe joint 20.

[0077] With this configuration, when the tube 12 is connected to the tube connection portion 14, the degree of freedom of deformation of the sealing member 30 can be increased compared to a configuration in which the sealing member is provided along the tip of the pipe joint.

[0078] Furthermore, in the piping structure 10 of this embodiment, the through-hole 32 is formed radially inward from the radially outer end of the groove wall 24.

[0079] According to this configuration, the strength of the groove wall 24 in which the through-hole 32, which serves as a gate, is formed can be maintained.

[0080] The mold 40 of this embodiment is an injection molding mold 40 for molding a pipe joint 20 in a piping structure 10 which includes a pipe joint 20 having a tube connection portion 14 with an annular groove 26 formed therein and a sealing member 30 provided in the annular groove 26. The main body portion 42 and the first mold 44, which are the parts that form the tube connection portion 14, are provided with a slidable second die portion 48 having a hole-punching portion 34 that forms a through hole 32 that penetrates the groove wall 24 of the annular groove 26.

[0081] According to this configuration, it is possible to provide a mold 40 for a pipe fitting 20 that does not produce gate marks on the sealing surface.

[0082] Furthermore, in the mold 40 of this embodiment, the punching portion 34 extends in the sliding direction X, and the sliding direction of the second piece portion 48 is the same as the direction in which the punching portion 34 extends.

[0083] With this configuration, the hole-punching portion 34 forms a through hole 32 in accordance with the sliding of the second piece portion 48. Therefore, compared to a configuration in which the sliding of the second piece portion and the formation of the through hole by the hole-punching portion are unrelated, the formation of the through hole 32 becomes easier.

[0084] The manufacturing method for the pipe fitting 20 of this embodiment is a method for manufacturing a pipe fitting 20 in which a tube 12 is connected to a tube connection portion 14 by providing a sealing member 30 in an annular groove 26 formed on the outer circumferential surface of the tube connection portion 14 of a resin pipe fitting 20, and the method comprises the steps of forming the pipe fitting 20 by injecting a first resin into a first cavity C1 with a gate 56 for injection molding the sealing member 30 partitioned in the groove wall 24 of the annular groove 26, and forming a sealing member 30 by injecting a second resin into a second cavity C2 via the gate 56 with a second mold 50 positioned on the outer circumferential side of the tube connection portion 14 after the first mold 44 has been removed.

[0085] According to this manufacturing method, it is possible to manufacture a pipe fitting 20 in which no gate marks are generated on the sealing surface.

[0086] Furthermore, in the manufacturing method of the pipe joint 20 of this embodiment, the gate 56 is defined as a hole-cutting portion 34 that becomes a through hole 32 in the groove wall 24 of the annular groove 26.

[0087] According to this manufacturing method, the gate 56 can be formed with a simple configuration.

[0088] <Variation> Although this disclosure has described in detail certain embodiments, it will be apparent to those skilled in the art that this disclosure is not limited to these specific embodiments, and that it can take various other embodiments within the scope of this disclosure.

[0089] The following modifications share the same basic configuration as the above embodiment and, if they have the same name, are described as having the same function.

[0090] In the piping structure 10 according to the above embodiment, a through hole 32 is formed in the groove wall 24 of the annular groove 26, but it is not limited to this. In a modified piping structure 110, for example, a pipe joint 120 in which a sealing member 130 is provided in the annular groove 126, as shown in Figures 10 and 11, the gate 156 (see Figure 13) for forming the sealing member 130 by injection molding of the second resin may be a notch 132 formed by partially cutting out the outer circumferential surface of the groove wall 124 of the annular groove 126.

[0091] In the mold 40 according to the above embodiment, a second die portion 48 is provided which has a punching portion 34 that forms a through hole 32 that penetrates the groove wall 24 of the annular groove 26, but the invention is not limited to this.

[0092] For example, in the modified mold 140, as shown in Figure 12, the second piece portion 148 may be provided with a protrusion 134 instead of the hole-punching portion 34 of the second piece portion 48 in the above embodiment. In other words, the second piece portion 148 has a protrusion 134 that forms a notch 132 by partially cutting out the outer circumferential surface of the groove wall 124 of the annular groove 126.

[0093] In this case, the second piece portion 148, together with the first piece portion 146, constitutes the first mold 144. The first mold 144, together with the main body portion 42, partitions the first cavity C11 and is used for primary molding. In the modified mold 140, as shown in Figure 13, in secondary molding, the second mold 150, together with the pipe joint 120 formed in primary molding, partitions the second cavity C22. The second mold 150 is appropriately formed with a runner 154, a gate 156, and a small piece portion 158.

[0094] In the manufacturing method of the pipe joint 20 according to the above embodiment, the gate is defined as a perforated portion, but it is not limited to this. For example, in the manufacturing method of the modified pipe joint 120, as shown in Figures 11 and 12, the gate may be defined as a protrusion 134 which becomes a notch 132 formed by cutting out a part of the outer circumferential surface of the groove wall 124 of the annular groove 126.

[0095] This manufacturing method makes it easier to control the gate position compared to a configuration in which through holes 32 are formed. [Explanation of Symbols]

[0096] 10, 110 Piping structure 12 tubes 14 Tube connection 16 Main body 16A Outer surface 20, 120 pipe fittings 22 Tip 24, 124 trench wall 26, 126 Annular groove 28 Retaining part 30, 130 sealing members 30A end face 32 Through holes 34 Hole cutout section 40, 140 molds 42 Main body 44, 144 First mold 46, 146 1st Komabe 48 2nd Komabe 50 Second mold 54, 154 runners Gates 56, 156 58, 158 Small piece part 132 Notch 134 Convex part C1, C11 First Cavity (An example of a cavity in the first mold) C2, C22 Second cavity (an example of a cavity consisting of the second mold and the tube connection part)

Claims

1. In a piping structure including a pipe fitting having a tube connection portion with an annular groove formed therein, a sealing member provided in the annular groove, and a tube connected to the tube connection portion with the sealing member provided in the annular groove, The tube connection portion has a through hole that penetrates the groove wall of the annular groove, or a notch formed by partially cutting out the outer surface of the groove wall of the annular groove. A piping structure in which the through hole or notch functions as a gate for injection molding the sealing member.

2. The tube connection portion has a retaining portion that slopes radially outward from the tip end to the base end of the pipe joint, The through hole is inclined in the direction in which the retaining portion is inclined. The piping structure according to claim 1.

3. The sealing member is provided along one groove wall of the annular groove, The through hole or notch is formed in the wall of one of the grooves. The piping structure according to claim 1.

4. The sealing member is provided in a manner that separates it from the other groove wall of the annular groove. The piping structure according to claim 3.

5. The through-hole is formed radially inward from the outer edge of the groove wall in the annular groove. The piping structure according to claim 1.

6. An injection molding die for forming a pipe joint in a piping structure, which includes a pipe joint having a tube connection portion with an annular groove formed therein, and a sealing member provided in the annular groove, The mold is provided with a slidable piece portion having a hole-punching portion that forms a through hole penetrating the groove wall of the annular groove, or a protrusion that forms a notch that partially cuts out the outer surface of the groove wall of the annular groove, in the portion that forms the tube connection portion.

7. The mold according to claim 6, wherein the punching portion extends in one direction, and the sliding direction of the die portion is the same as the direction in which the punching portion extends.

8. A method for manufacturing a pipe joint, wherein a sealing member is provided in an annular groove formed on the outer surface of a resin tube connection part, and the tube is connected to the tube connection part. The process involves forming the tube connection portion by injecting the first resin into the cavity of the first mold, with a gate for injection molding the sealing member demarcated in the groove wall of the annular groove, The process includes the step of forming the sealing member by injecting the second resin through the gate into the cavity formed by the second mold and the tube connection portion, with the second mold positioned on the outer circumference of the tube connection portion after the first mold has been removed. A method for manufacturing pipe fittings.

9. The gate is defined as a hole-cutting portion that forms a through-hole in the groove wall of the annular groove, or as a protruding portion that forms a notch in which a part of the outer surface of the groove wall of the annular groove is cut out. A method for manufacturing a pipe joint according to claim 8.

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