JP4573846B2 - Conversion joint and manufacturing method thereof - Google Patents

Description

  The present invention relates to a conversion joint used when a metal pipe such as a steel pipe and a synthetic resin pipe such as a polyethylene pipe are connected to each other and a method for manufacturing the same.

  Recently, for underground pipes for liquefied petroleum gas (LPG) buried in the ground, the existing steel pipes have been replaced with polyethylene pipes (hereinafter referred to as “PE pipes”). Conversion joints may be used. A conversion joint suitable for this application needs to have a connection port portion to which a steel pipe can be connected and a connection port portion to which a PE pipe can be connected. In general, the connection port portion for the steel pipe is a metal tube. The connection port portion for the PE pipe is provided integrally with a synthetic resin layer that is injection-molded on the outer side or the inner side of the cylindrical body.

  However, simply by injection molding a synthetic resin layer on the outside or inside of a metal cylinder and then integrally injection-molding the connection port for the PE tube into the synthetic resin layer, the metal cylinder and the synthetic resin A gap is generated at an overlapping portion with the layer, and the gap causes gas leakage.

  Therefore, conventionally, as shown in FIG. 7, a rubber seal ring (O-ring) 83 is housed in a seal ring housing groove 82 formed in an annular shape in a metal cylinder 81, and as such. A synthetic resin layer 84 is injection-molded on the outside of the cylinder 81 holding the seal ring 83 as shown by phantom lines in the drawing, and a connection port portion continuously provided to the synthetic resin layer 84 at the time of the injection molding. 85 was injection molded. In the figure, a PE pipe is connected to the connection port 85. Further, the steel pipe is connected to a connection port portion 86 provided continuously to the cylinder 81.

  In the manufacturing method of the conversion joint described in FIG. 7, the gap at the overlapping portion between the cylinder 81 and the synthetic resin outer layer 84 is hermetically sealed by the seal ring 83 compressed by the molding pressure when the synthetic resin layer 84 is injection molded. Standing on the idea of closing.

  However, when a hot internal pressure creep test is performed on the conversion joint made by the manufacturing method described with reference to FIG. 7, the synthetic resin layer 84 expands and the surface pressure of the seal ring 83 decreases. It has been found that airtightness is often lost and gas leakage often occurs. The hot internal pressure creep test is a test for confirming the presence or absence of gas leakage when a sample is submerged in warm water of 80 ± 1 ° C., an air pressure of 1.2 MPa is applied, and the pressure is maintained for 30 hours.

  As the cause of the conventional conversion joint causing gas leakage by the hot internal pressure creep test as described above, the following causes are considered. In other words, depending on the molding pressure when the synthetic resin layer 84 is injection-molded, the seal ring 83 is not compressed or is not sufficiently compressed. For this reason, the seal ring 83 and the seat surface on the cylindrical body 81 side are not compressed. One of the causes is considered to be that airtightness by the seal ring 83 is not secured because the molding resin that has entered overlaps the bottom surface of the seal ring housing groove 82.

  The present invention has been made in view of the above situation, and the seal ring held by the metal cylinder is in close contact with both the cylinder and the synthetic resin layer outside the cylinder. It aims at providing the conversion coupling which exhibits airtightness.

  Further, the present invention provides a method for manufacturing a conversion joint in which the phenomenon that the molding resin does not sink into the seal ring and the seating surface on the cylindrical body side or hardly occurs when the synthetic resin layer is injection molded. The purpose is to provide.

  Furthermore, this invention aims at providing the manufacturing method of the conversion coupling which can make the conversion coupling which seal ring closely_contact | adheres to both a metal cylinder and a synthetic resin layer, and exhibits high airtightness. And

In the conversion joint according to the first aspect of the present invention, a rubber seal ring is externally fitted to a metal cylinder having a first connection port portion with respect to a metal tube connected to an end, and the rubber fitting is externally fitted to the seal ring. The seal ring is pressed and compressed by the combined synthetic resin ring-shaped pressing body and the cylindrical body, and the seal ring is provided on the inner peripheral side of the ring-shaped pressing body. When the ring-shaped pressing body is externally fitted to the seal ring on the inner peripheral side of the end of the ring-shaped pressing body, the seating surface is in close contact with the outer peripheral seating surface provided on the outer peripheral side of the cylindrical body. A flared guide surface is formed for sliding the seal ring to guide to the inner peripheral seat surface, and the inner diameter of the ring-shaped pressing body is fitted to the outer peripheral seat surface of the cylindrical body. It is set to be smaller than the outer peripheral diameter of the ring, the phosphorus The Jo pressing body, metal reinforcing ring to prevent expansion of the ring-shaped pressing body due to heat during the injection molding of the molding material of the synthetic resin layer overlap to form fitted, these ring-shaped pressing member and the reinforcing The synthetic resin layer covering the ring from the outside is formed in a cylindrical shape on the outside of the cylindrical body, and the synthetic resin layer and the ring-shaped pressing body are fused and integrated by the heat , and the synthetic resin layer is A synthetic resin second connection port portion for the synthetic resin pipe is provided continuously. According to this invention, the metal tube is connected to the first connection port portion provided continuously with the cylindrical body, and the synthetic resin tube is connected to the second connection port portion provided continuously with the synthetic resin layer. In addition, the airtightness between the metal cylinder and the synthetic resin layer is such that the ring-shaped pressing body fused and integrated with the synthetic resin layer cooperates with the cylinder to compress and seal the seal ring. In addition, the seal ring is maintained by being in close contact with the inner peripheral seating surface on the inner peripheral side of the ring-shaped pressing body and the outer peripheral seating surface on the outer peripheral side of the cylindrical body. Further, on the inner peripheral side of the end of the ring-shaped pressing body, when the ring-shaped pressing body is fitted to the seal ring, the seal ring slides and guides to the inner peripheral seat surface. Since the surface is formed, when the ring-shaped pressing body is externally fitted to the seal ring, the seal ring is not damaged and the seal ring is appropriately compressed by the ring-shaped pressing body and the cylindrical body. It is possible to leave.

  In the conversion joint according to the first aspect of the present invention, a metal reinforcing ring is overlapped with the ring-shaped pressing body in an outer fitting shape, and the ring-shaped pressing body made of synthetic resin is expanded by the metal reinforcing ring. Therefore, the initial surface pressure of the seal ring against the inner peripheral seating surface and the outer peripheral seating surface is not easily lowered.

  The conversion joint according to a second aspect of the present invention is the conversion joint according to the first aspect, wherein the outer peripheral seating surface is formed in an annular shape on the outer peripheral portion of the cylindrical body, and the bottom surface of the seal ring receiving groove portion for storing the seal ring. The inner peripheral seating surface is formed on the inner peripheral surface extending in the axial direction while maintaining the same diameter provided in the ring-shaped pressing body. Also according to this invention, the same effect as that of the invention according to claim 1 is exhibited.

Method for producing a conversion joint of the invention according to claim 3, the rubber seal ring first joint port is fitted outside the tubular body made of metal which is continuously provided on the end portion to the metal tube, the tube A ring-shaped pressing body made of synthetic resin, which is set so that its inner diameter is smaller than the outer diameter of the seal ring fitted to the outer peripheral seating surface provided on the outer peripheral side of the body, is provided on the outer periphery of the cylindrical body. Slide the guide surface formed on the inner peripheral side of the end of the ring-shaped pressing body and the seal ring to externally fit the ring-shaped pressing body, and form a synthetic resin layer on the ring pressing body. A reinforcing ring that prevents expansion of the ring-shaped pressing body due to heat at the time of injection molding of the molding material is externally fitted, and the seal ring is pressed by the ring-shaped pressing body and the cylindrical body to remove the seal ring. Inner peripheral seating surface provided on the inner peripheral side of the ring-shaped pressing body and above Is brought into close contact with the outer circumferential seat surface which is provided on the outer peripheral side of the cylindrical body, then injection molding the synthetic resin layer covering the ring-shaped pressure body and the reinforcing ring on the outside of the tubular body into a tubular shape, its Simultaneously with the injection molding of the synthetic resin layer, the second connecting port made of synthetic resin for the synthetic resin pipe is continuously injection molded to the synthetic resin layer. In this invention, prior to injection molding of the synthetic resin layer and the second connection port, the seal ring is in close contact with the outer peripheral seating surface of the cylinder, and the close contact state presses the seal ring into a ring shape. It is obtained by pressing with a body and the cylinder. For this reason, when the synthetic resin layer is injection-molded, a situation in which the molding resin sinks between the seal ring and the outer peripheral seat surface is less likely to occur or does not occur. Therefore, according to the present invention, the above-described conversion joint according to the present invention can be manufactured.

  According to a fourth aspect of the present invention, there is provided the conversion joint manufacturing method according to the third aspect, wherein when the synthetic resin layer is injection-molded, the ring-shaped pressing body is heated by the heat of the molding resin of the synthetic resin layer. The synthetic resin layer is heat-sealed. According to the present invention, the conversion joint according to the present invention in which the ring-shaped pressing body and its outer layer are fused and integrated can be manufactured.

  According to a fifth aspect of the present invention, there is provided the conversion joint manufacturing method according to the third or fourth aspect, wherein the outer peripheral seating surface of the seal ring is pressed by the ring-shaped pressing body and the cylindrical body. The surface pressure with respect to is made higher than the molding pressure at the time of injection molding of the synthetic resin layer. According to this invention, when the synthetic resin layer is injection-molded, there is no possibility that the molding resin will sink between the seal ring and the outer peripheral seating surface. Therefore, according to the present invention, the above-described conversion joint according to the present invention can be manufactured.

  According to the conversion joint according to the present invention, even if a gap is generated between the metal cylinder to which the metal pipe is connected and the outer layer made of the synthetic resin to which the synthetic resin pipe is connected, the gap is formed between the cylinder and the cylinder. There is an effect of exhibiting high airtightness by adhering to both the outer layer.

  According to the manufacturing method of the conversion joint according to the present invention, when the outer layer made of synthetic resin is injection-molded on the outer side of the metal cylinder, the phenomenon that the molding resin sinks inside the seal ring is less likely to occur, Alternatively, since it does not occur, a conversion joint with high adhesion reliability of the seal ring to both the cylinder and the outer layer can be manufactured.

  The conversion joint A which is a reference form is demonstrated with reference to FIG. The conversion joint A includes a metal cylinder 1 and a synthetic resin outer layer 2 provided outside the cylinder 1. A first connecting port portion 12 having a large diameter is concentrically connected to the cylindrical body 1, and, for example, a metal pipe (steel pipe) which is a counterpart is connected to a taper female screw 13 provided in the first connecting port portion 12. Etc.) are connected by screwing. Further, the connection port portion 12 is formed to have a diameter larger than that of the cylindrical body 1, and the opening angle with respect to the outer peripheral surface of the cylindrical body 1 is perpendicular to the connection portion between the first connection port portion 12 and the cylindrical body 1. An end face 14 of the first connection port portion 12 is located.

  In the cylindrical body 1, an annular seal ring receiving groove 15 formed in a recessed shape in the outer peripheral portion of the cylindrical body 1 is formed near the end face 14 of the first connection port portion 12. The seal ring receiving groove 15 is formed to receive and position a seal ring 3 to be described later, and the bottom surface of the receiving groove 15 is formed on the outer peripheral side of the cylindrical body 1. It is set to 16. The rubber seal ring 3 that is externally fitted to the cylindrical body 1 and accommodated in the seal ring accommodation groove 15 is in close contact with the outer peripheral seating surface 16.

A rubber O-ring can be suitably used for the seal ring 3 housed in the seal ring housing groove 15. A ring-shaped pressing body 4 made of synthetic resin is externally fitted to the seal ring 3. The ring-shaped pressing body 4 has an inner diameter that is slightly shorter than the outer peripheral diameter of the seal ring 3 fitted to the outer peripheral seating surface 16. Therefore, the seal ring 3 is pressed and compressed by the ring-shaped pressing body 4 and the cylindrical body 1, and the inner peripheral seating surface provided with the seal ring 3 on the inner peripheral side of the ring-shaped pressing body 4. 41 and the outer peripheral seating surface 16 of the cylinder 1 are in close contact with each other. The inner peripheral seat surface 41 is formed by an inner peripheral surface that is provided in the ring-shaped pressing body 4 and that extends in the axial direction while maintaining the same diameter. Further, when the ring-shaped pressing body 4 is fitted on the seal ring 3 on the inner peripheral side of the end of the ring-shaped pressing body 4, the seal ring 3 is slid and guided to the inner peripheral seating surface 41. An expanding guide surface 41a is formed. For this reason, when the ring-shaped pressing body 4 is externally fitted to the seal ring 3, the seal ring 3 is not damaged, and in the state where the ring-shaped pressing body 4 is externally fitted to the seal ring 3, The seal ring is appropriately compressed by the pressing body 4 and the cylindrical body 1. The guide surface 41a may be an inclined flat tapered surface or a curved surface (R-shaped surface) as long as it is widened. Furthermore, a metal reinforcing ring 42 is overlapped on the ring-shaped pressing body 4 in an outer fitting shape. The reinforcing ring 42 is provided to prevent the ring-shaped pressing body 4 made of synthetic resin from expanding.

  A synthetic resin outer layer 2 is formed surrounding the cylindrical body 1, the first connection port portion 12, and the ring-shaped pressing body 4. The outer layer 2 is fused and integrated with the ring-shaped pressing body 4 at a location where the outer layer 2 contacts the ring-shaped pressing body 4. Further, a second connection port portion 22 made of a synthetic resin is connected to the outer layer 2, and a synthetic resin pipe (not shown) is connected to the second connection port portion 22.

  In this conversion joint A, the seal ring 3 compressed by the cylinder 1 and the ring-shaped pressing body 4 is compressed by the outer peripheral seating surface 16 on the cylindrical body 1 side and the inner peripheral seat on the ring-shaped pressing body 4 side. It is in close contact with both the surface 41 and the ring-shaped pressing body 4 is fused and integrated with the outer layer 2. Therefore, even if there is a gap at the overlapping portion between the cylinder 1 and the outer layer 2, the gap is sealed by the seal ring 3 at the seal ring 3. Therefore, the airtightness between the metal cylinder 1 and the synthetic resin outer layer 2 is reliably maintained by the seal ring 3. Further, since the ring-shaped pressing body 4 is prevented from expanding by the metal reinforcing ring 42, a seal ring for the inner peripheral seat surface 41 and the outer peripheral seat surface 16 resulting from the expansion of the ring-shaped pressing body 4. The initial surface pressure of 3 is difficult to decrease.

  The conversion joint A of this invention is demonstrated with reference to FIG. In this conversion joint A, the difference from that described in FIG. 3 is that the groove wall surface 17 on one side of the seal ring housing groove portion 15 is formed by the inner peripheral portion of the end surface 14 of the first connection port portion 12. The groove wall 18 on the other side of the seal ring housing groove 15 is formed by the inner surface of the ring-shaped protrusion 5 provided on the cylindrical body 1 so as to face the end surface 14, the ring-shaped pressing body 4 is It is fitted in the seal ring housing groove 15 and is sandwiched between the end surface 14 of the first connection port 12 and the inner surface of the ridge 5 (the groove wall surface 18). This conversion joint A also exhibits the same effect as the conversion joint A described with reference to FIG. In addition, since it is the same as that of the conversion coupling A demonstrated in FIG. About the structure and effect | actions other than above-mentioned, the same code | symbol is attached | subjected to a corresponding part and detailed description is abbreviate | omitted.

  Next, the manufacturing method of the conversion joint A of FIG. 3 is demonstrated with reference to FIGS.

  The outer layer 2 made of a synthetic resin shown in FIG. 3 and the second connection port portion 22 connected to the outer layer 2 are formed by injection molding using a synthetic resin such as a polyethylene resin as a molding material. Prior to the molding of the outer layer 2, the seal ring 3 externally fitted to the cylinder 1 is accommodated and held in the seal ring accommodation groove 15 as shown in FIG. 1. Further, the cylindrical body 1 is fitted with a ring-shaped pressing body 4 reinforced by a reinforcing ring 42. From this state, as shown by an arrow a in FIG. 2, the ring-shaped pressing body 4 is slid onto the cylindrical body 1, and the guide surface 41 a and the seal ring 3 are slid and fitted to the seal ring 3. Thus, the seal ring 3 is pressed and compressed between the inner peripheral seat surface 41 of the ring-shaped pressing body 4 and the outer peripheral seat surface 16 of the cylindrical body 1. In this case, when the ring-shaped pressing body 4 is brought into contact with the end face 14 of the first connection port portion 12 as shown in FIG. It is desirable to keep it, and if so, the work of fitting the ring-shaped pressing body 4 to the seal ring 3 can be performed easily and reliably.

  Next, as shown in FIG. 3, the outer layer 2 of synthetic resin is injection-molded on the outside of the cylindrical body 1 and the ring-shaped pressing body 4. Further, when the outer layer 2 is injection-molded, the second connection port is also injection-molded.

  When such a manufacturing method is adopted, when the outer layer 2 and the second connection port portion 22 are injection-molded, the seal ring 3 pressed by the ring-shaped pressing body 4 and the cylinder 1 is formed on the outer peripheral seat of the cylinder 1. Since it is in close contact with the surface 16, a situation in which the molding resin enters the inside of the seal ring 3 during the injection molding of the outer layer 2 becomes difficult or does not occur. Further, when the ring-shaped pressing body 4 is made of the same type of synthetic resin as the molding material of the outer layer 2 such as polyethylene resin or a compatible synthetic resin, the molding resin of the outer layer 2 is formed when the outer layer 2 is injection molded. The ring-shaped pressing body 4 and its outer layer 2 are heat-sealed by the heat. Therefore, by doing so, the conversion joint A already described with reference to FIG. 3 is easily manufactured.

  In this manufacturing method, when the synthetic resin outer layer 2 is injection-molded, even if the synthetic resin ring-shaped pressing body 4 is softened by the heat of the molding material, the ring-shaped pressing body 4 is expanded due to the softening. Is prevented by the metal reinforcing ring 42, the ring-shaped pressing body 4 does not expand after the injection molding of the outer layer 2, and the surface pressure of the seal ring does not decrease. In particular, in this manufacturing method, the surface pressure against the outer peripheral seating surface 16 of the seal ring 3 pressed by the ring-shaped pressing body 4 and the cylindrical body 1 is used as the molding pressure at the time of injection molding of the outer layer 2 (the injection pressure of the molding material). It is desirable to keep it higher. In this way, when the outer layer 2 is injection-molded, there is no possibility of a situation in which the molding resin sinks inside the seal ring 3.

  Still another manufacturing method of the conversion joint A will be described with reference to FIGS. The cylindrical body 1 used in this manufacturing method has a ring-shaped ridge 5, and the outer surface of the ridge 5 is a tapered guide surface 51. On the other hand, the inner pressing portion 43 is provided integrally with the ring-shaped pressing body 4. The other structure of the cylindrical body 1 is as described above for the conversion joint A in FIG.

The outer layer 2 made of synthetic resin shown in FIG. 6 and the second connection port portion 22 connected to the outer layer 2 are formed by injection molding using synthetic resin such as polyethylene resin as a molding material. Prior to the molding of the outer layer 2, the seal ring 3 externally fitted to the cylindrical body 1 is accommodated and held in the seal ring accommodating groove 15 as shown in FIG. 4. Further, the cylindrical body 1 is fitted with a ring-shaped pressing body 4 reinforced by a reinforcing ring 42. From this state, as shown by an arrow b in FIG. 5, the ring-shaped pressing body 4 is slid onto the cylindrical body 1, and the inner flange portion 43 of the ring-shaped pressing body 4 is slid with the guide surface 51 of the ridge 5. Then, the ridge 5 is moved over the inner collar portion 43. If it does in this way, the ring-shaped press body 4 will fit in the seal ring accommodation groove part 15, and the ring-shaped press body 4 will fit outside the seal ring 3. FIG. Thereby, the ring-shaped pressing body 4 is sandwiched between the end surface 14 of the first connection port portion 12 and the inner surface of the ridge 5, and the seal ring 3 is pressed by the cylindrical body 1 and the ring-shaped pressing body 4. As a result, the seal ring 3 comes into close contact with the outer peripheral seating surface 16. Next, as shown in FIG. 6, the outer layer 2 of synthetic resin is injection-molded on the outside of the cylindrical body 1 and the ring-shaped pressing body 4. Further, when the outer layer 2 is injection-molded, the second connection port is also injection-molded.

  Even by adopting such a manufacturing method, a situation in which the molding resin enters the inside of the seal ring 3 during the injection molding of the outer layer 2 does not occur. Also in this manufacturing method, if the ring-shaped pressing body 4 is made of the same type of synthetic resin as the molding material of the outer layer 2 such as polyethylene resin or a compatible synthetic resin, the outer layer 2 can be formed by injection molding. The ring-shaped pressing body 4 and its outer layer 2 are heat-sealed by the heat of the molding resin 2. Further, when the outer layer 2 of the synthetic resin is injection-molded, even if the ring-shaped pressing body 4 made of synthetic resin is softened by the heat of the molding material, the expansion of the ring-shaped pressing body 4 accompanying the softening is made of metal. Therefore, after the outer layer 2 is injection molded, the ring-shaped pressing body 4 does not expand and the surface pressure of the seal ring does not decrease. In particular, in this manufacturing method, the surface pressure against the outer peripheral seating surface 16 of the seal ring 3 pressed by the ring-shaped pressing body 4 and the cylindrical body 1 is used as the molding pressure at the time of injection molding of the outer layer 2 (the injection pressure of the molding material). It is desirable to keep it higher. In this way, when the outer layer 2 is injection-molded, there is no possibility of a situation in which the molding resin sinks inside the seal ring 3.

It is a partial vertical side view of the cylinder which fitted the seal ring outside. It is a partial vertical side view of the state which carried out the external fitting of the ring-shaped press body to the seal ring. It is a partial vertical side view of the conversion joint which is a reference form. It is a partial vertical side view of the other cylinder body which fitted the seal ring outside. It is a partial vertical side view of the state which carried out the external fitting of the ring-shaped press body to the seal ring. It is a partial vertical side view of the conversion joint of this invention. It is a partial vertical side view of the state which fitted the seal ring in the cylinder used for the conventional manufacturing method.

1 cylinder 2 outer layer (synthetic resin layer)
DESCRIPTION OF SYMBOLS 3 Seal ring 4 Ring-shaped press body 12 1st connection port part 14 End surface of 1st connection port part 15 Seal ring accommodation groove part 16 Outer peripheral seat surface 17, 18 Groove wall surface 22 2nd connection port part 41 Inner peripheral seat surface 41a Guide surface 42 Reinforcement ring

Claims (5)

A rubber seal ring is externally fitted to a metal cylinder having a first connection port portion connected to the end of the metal tube, and a synthetic resin ring-shaped pressing body externally fitted to the seal ring. And the cylinder are pressed and compressed by the cylindrical body, and the seal ring is provided on the inner circumferential seat surface provided on the inner circumferential side of the ring-shaped pressing body and on the outer circumferential side of the cylindrical body. When the ring-shaped pressing body is fitted to the seal ring, the seal ring is slid on the inner peripheral side of the end of the ring-shaped pressing body. A flared guide surface is formed to guide the surface ,
The inner diameter of the ring-shaped pressing body is set to be smaller than the outer diameter of the seal ring fitted to the outer peripheral seating surface of the cylindrical body ,
In this ring-shaped pressing body, a metal reinforcing ring that prevents the ring-shaped pressing body from spreading due to heat at the time of injection molding of the molding material forming the synthetic resin layer overlaps with the outer fitting shape, and these ring-shaped pressing body and the synthetic resin layer covering the reinforcing ring from the outside is formed on the outside of the tubular body into a tubular shape,
The synthetic resin layer and the ring-shaped pressing body are fused and integrated by the heat ,
A conversion joint, wherein a synthetic resin second connection port portion for a synthetic resin pipe is connected to the synthetic resin layer.   The outer peripheral seating surface is formed in an annular shape on the outer peripheral portion of the cylindrical body, and is formed on the bottom surface of the seal ring receiving groove portion for receiving the seal ring, and the inner peripheral seating surface is provided on the ring-shaped pressing body. The conversion joint according to claim 1, wherein the conversion joint is formed on an inner peripheral surface extending in the axial direction while maintaining the same diameter. To a rubber seal ring that is externally fitted to a metal cylinder having a first connection port with respect to the metal tube connected to the end,
A ring-shaped pressing body made of synthetic resin, which is set so that its inner diameter is smaller than the outer diameter of the seal ring fitted to the outer peripheral seating surface provided on the outer peripheral side of the cylindrical body, is provided outside the cylindrical body. Slide around the circumference, slide the guide surface formed on the inner peripheral side of the end of the ring-shaped pressing body and the seal ring, and externally fit the ring-shaped pressing body,
The ring pressing body is externally fitted with a reinforcing ring that prevents the ring-shaped pressing body from spreading due to heat during injection molding of the molding material forming the synthetic resin layer ,
The seal ring was pressed by the ring-shaped pressing body and the cylindrical body, and the seal ring was provided on the inner peripheral seating surface provided on the inner peripheral side of the ring-shaped pressing body and on the outer peripheral side of the cylindrical body. Close contact with the outer peripheral seating surface,
Then, the synthetic resin layer on the outer side of the cylindrical body to cover the ring-shaped pressure body and the reinforcing ring is injection molded into a cylindrical shape, simultaneously with the injection molding of the synthetic resin layer, a synthetic resin for the synthetic resin tube A conversion joint manufacturing method, wherein the second connection port portion is continuously injection-molded to the synthetic resin layer.   The method for manufacturing a conversion joint according to claim 3, wherein when the synthetic resin layer is injection-molded, the ring-shaped pressing body and the synthetic resin layer are heat-sealed with heat of the molding resin of the synthetic resin layer.   The surface pressure with respect to the said outer peripheral seating surface of the said seal ring pressed by the said ring-shaped press body and the said cylinder is made higher than the molding pressure at the time of the injection molding of the said synthetic resin layer. Item 5. A method for manufacturing a conversion joint according to Item 4.

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