JP2005163960A - Cap with purge port - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact cap with a purge port, allowing a metallic stand pipe to be directly screwed in without deforming a purge opening. <P>SOLUTION: This cap with the purge port is composed of a tubular body 2 made out of a thermoplastic resin, and having a receiving port 3 for inserting a resin tube 20 at its one end side in a state of burying a heating wire 6 forming a fusion joining part with the resin tube 20 at an inner periphery of the receiving port 3, and a bottom part 4 at the other end side, and a bush 8 having a taper screw 82 for the tube having the purge opening 80 at its inner peripheral side, and made out of a material having mechanical strength higher than that of the resin of the tubular body 2, is fixed to the bottom part 4 of the tubular body 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a purge cap used at the end of a pipe, and more particularly to an electrofusion purge cap with a metal pipe that can be directly connected to a purge port.

In various gas pipes containing city gas, for example, pipes are made using PE pipes, but there are various problems if air remains in the pipes. The gas supply is started after purging the air inside. Therefore, a PE cap having a purge hole sealed with a lid or the like is put on the end of the PE pipe, and the PE pipe and the cap are fused and joined by energizing the heating wire built in the cap. In this case, the lid is removed, a metal stand pipe is connected to the purge hole and air is discharged to the ground. After the purge operation is completed, the metal stand pipe is removed and the purge hole is sealed with the lid. It has been broken.
As the cap having the purge hole described above, for example, a receiving port for inserting a resin tube into one of the tube bodies (large diameter portion), and a male screw portion for screwing a lid for closing the opening into the other (small diameter portion). There has been proposed a tube end cap in which a heating wire is embedded in the inner periphery of the receiving port to melt the resin and fuse and bond the resin tube and the receiving port (see Patent Document 1).

JP 2000-9284 A (2nd page, FIG. 1)

  Since the cap described in Patent Document 1 is entirely formed of resin, there is a problem in that a connection portion with a metal standpipe is easily deformed. In other words, since the metal standpipe is directly screwed into the resin main body after purging, the male screw portion formed on the resin main body is easily deformed, and there is a problem in its sealing performance and pressure resistance, as defined in JIS K6774. There is a problem that the hot internal pressure creep test of the gas polyethylene pipe that is being used cannot be satisfied. Also, this male screw is not a pipe taper screw that is generally used as a connection screw, so a special tool or jig is required to connect to a metal standpipe during the purge operation. Further, since the male screw portion is provided on the outer periphery opposite to the receiving port, there is a problem that the entire length of the cap becomes long.

  An object of the present invention is to solve the above-mentioned problems, and to provide a compact cap with purge capable of directly screwing a metal standpipe without deformation of the purge port.

  In order to achieve the above object, the purged cap of the present invention has a receiving port into which a resin tube is inserted at one end side, and a fusion bonded portion with the resin tube is formed on the inner periphery of the receiving port. The heating element is embedded, and is formed of a tubular body formed of a thermoplastic resin having a bottom portion on the other end side. The bottom portion is made of a material having a mechanical strength higher than that of the thermoplastic resin and on the inner peripheral side. A purge port member having a pipe taper screw is fixed.

  In the present invention, the purge port member is an annular body having a flange portion provided on the inner peripheral surface of the bottom portion of the tubular body on one end side and a thread portion having a smaller diameter than the flange portion on the outer periphery, The annular body can be fixed to the bottom portion by fastening a nut to the screw portion.

  In the present invention, the purge port member may be an annular body inserted at the time of forming the tubular body.

  In the present invention, it is preferable that the resin pipe and the tubular body are formed of a polyolefin resin, and the purge port member is formed of a steel material.

  According to the purge cap of the present invention, since the pipe tap screw is provided at the purge port, the metal pipe can be attached and detached (purge operation) without using a special tool or jig, and the pipe taper is also provided. The purge port member with a screw is made of a material having a mechanical strength greater than that of the thermoplastic resin forming the tubular body, so it is difficult to deform even when the metal tube is attached or detached, and maintains a predetermined shape over a long period of time. can do. Further, the purge port can be provided eccentrically with respect to the axial center of the tubular body, and when the cap is attached to the tube end, it can be attached so that the purge port is easily purged.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a purged cap according to an embodiment of the present invention, FIG. 2 is an enlarged view of a portion A in FIG. 1, and FIG. 4 is a cross-sectional view showing a purged cap according to a second embodiment of the present invention, FIG. 5 is a cross-sectional view showing a purged cap according to a third embodiment of the present invention, and FIG. It is sectional drawing which shows the example which mounted | wore with the metal standpipe in the cap.

A cap with purge 1 shown in FIG. 1 includes a tubular body 2 having a receiving port 3 into which a resin tube 20 is inserted on one end side and a bottom portion 4 on the other end side. The dimension is set so as to receive the resin tube 20 to be inserted. On the inner peripheral side of the receiving port 3, a heating wire 5 for melting a thermoplastic resin that forms the tubular body 2 and the resin tube 20, for example, a polyolefin-based resin such as polyethylene, is embedded. It is connected to a terminal 6 provided on the outer periphery. A stopper portion 7 for restricting the insertion length of the resin tube 20 is provided inside the receiving port 3 at a position separated from the end face of the receiving port 3 by a predetermined distance. The tubular body 2 can be manufactured, for example, by separately preparing a portion in which the heating wire 5 is embedded and a portion including the bottom portion 4 and joining them together by a butt fusion technique. In this case, the bead portion formed on the inner peripheral side can be used as the stopper portion 7. A bush 8 having an axis C ₂ that is eccentric with respect to the axis C ₁ of the tubular body 2 is inserted into the bottom 4 of the tubular body 2. 2, the bush 8 is an annular body having a purge port 80 and a flange portion 81, and a metal tube 21 used in a purge operation within a predetermined length L is provided on the inner periphery of the bush 8. A pipe taper screw 82 to be screwed is formed, and a screw portion 83 is formed on the outer periphery. The bush 8 inserted into the bottom part 4 is integrated with the tubular body 2 by screwing a locking nut 84 into the threaded part 83. In order not to rotate the flange portion 81 with respect to the bottom portion 4, although not shown, for example, a part of the outer peripheral portion of the flange portion 81 may be protruded in the radial direction and embedded in the bottom portion 4. An O-ring 9 that is a seal member for preventing gas leakage is provided between the end face of the flange portion 81 and the inner peripheral surface of the bottom portion 5. The bush 8 is formed of a material having higher mechanical strength than the thermoplastic resin such as a metal material. As the metal material, for example, carbon steel for mechanical structure (JIS G 4051) such as S45C is preferably used from the viewpoint of mechanical strength and price. The tensile strength of polyethylene is, for example, about 8 to 23 MPa for LDPE and about 18 to 35 MPa for HDPE, whereas carbon steel for mechanical structure has a tensile strength of 314 MPa or more even in S10C (normalized), Since S45C (normalized) generally used has a tensile strength of 569 MPa or more, even if a metal pipe is attached to or detached from the bush 8 formed of carbon steel for mechanical structure, deformation of the pipe taper screw 82 is prevented. . Further, the bush 8 is preferably formed of a material having a mechanical strength equal to or higher than that of the metal tube 21 attached to and detached from the bush 8 in addition to the mechanical strength being higher than that of the thermoplastic resin. .

  The purged cap 1 configured as described above is attached to the end of a pipe serving as an exhaust port, for example, as shown in FIG. First, the resin tube 20 is inserted into the receiving port 4 until its end abuts against the stopper portion 7 provided inside the purged cap 1, and then the heating wire 8 is energized from the terminal 6 to surround the heating wire 6. The cap 1 with purge and the resin tube 20 are connected by melting the resin and fusion-bonding the inner periphery of the receiving port 4 of the bottomed tubular body 2 and the outer periphery of the resin tube 20. Next, the metal pipe (purge pipe) 21 connected to the tip of the metal standpipe 23 exposed to the ground via the elbow 22 is screwed into the pipe taper screw 82 of the bush 8 and then the exhaust operation is performed. Can remove the metal pipe 21 from the bush 8 and screw a metal plug (not shown) into the pipe taper screw 82 for sealing, thereby completing the purging operation in the pipe. According to this purge cap 1, since the purge port 80 is formed by the pipe taper screw 82, the metal pipe 21 can be easily attached and detached and the plug can be attached without using a special tool or jig. be able to. Moreover, since the purge port 80 is formed of the bush 8 made of a material having a mechanical strength far higher than that of the resin forming the tubular body 2 described above, the purge port 80 is prevented from being deformed due to the attachment / detachment of the metal tube. be able to. Further, in the above-mentioned purged cap 1, the bush 8 is eccentric with respect to the axial center of the purged cap 1, so that even when a gas lighter than air such as natural gas stays in the tubular body 2. The purge port 80 is located at a position facing the air, so that the purge operation can be performed reliably.

  The purge cap 1 of the present invention may have the structure shown in FIG. 4, and in FIG. 4, the same functional parts as those in FIG. 1 are denoted by the same reference numerals. The purge cap 1 of FIG. 4 includes a tubular body 2 having a receiving port 3 into which a resin tube 20 is inserted on one end side and a bottom portion 4 on the other end side, like the cap of FIG. 3 is embedded with a heating cap 5 for melting the resin that forms the purged cap 1 and the resin tube 20, and both ends thereof are connected to terminals 6 provided on the outer periphery of the receiving port 3. A bush 8 having an axial center eccentric to the axial center of the tubular body 2 is inserted into the bottom 4 of the tubular body 2. The bush 8 has a purge port 80 and flanges 81, 81 at both ends, and a taper screw 82 for a pipe into which a metal pipe 21 used during a purge operation is screwed is formed on the inner periphery thereof. ing. Although not shown, the bush 8 is inserted into a molding die, for example, when the tubular body 2 is manufactured by an injection molding technique, and is cooled and solidified after pouring molten resin into the molding cavity of the die. It is integrated with the tubular body 2 by (insert molding).

  The purged cap 1 of the present invention may have the structure shown in FIG. 5, and in FIG. 5, the same functional parts as those in FIG. 1 are denoted by the same reference numerals. The cap with purge 1 of FIG. 5 includes a tubular body 2 having a receiving port 3 into which a resin tube 20 is inserted at one end side and a bottom portion 4 at the other end side, like the cap of FIG. 3 is embedded with a heating cap 5 for melting the resin that forms the purged cap 1 and the resin tube 20, and both ends thereof are connected to terminals 6 provided on the outer periphery of the receiving port 3. ing. A step portion 31 having a smaller diameter than the inner surface of the receiving port 3 is formed at a position separated from the end surface of the receiving port 3 by a predetermined distance. A bush 8 having an axial center that is eccentric with respect to the axial center of the tubular body 2 is inserted into the bottom 4 of the tubular body 2. The bush 8 is integrated with the tubular body 2 by screwing a locking nut 84 to the outer periphery thereof. According to the purged cap 1, as shown in FIG. 6, first, the resin tube 20 is inserted into the receiving port 3 until the end of the resin tube 20 comes into contact with the stepped portion 31 provided inside the purged cap 1, By supplying electricity to the heating wire 5 from the terminal 6 to melt the resin around the heating wire 5, the inner peripheral portion of the receiving port 4 of the tubular body 2 and the outer peripheral portion of the resin tube 20 are fused and joined. The cap 1 and the resin pipe 20 are connected. Next, after the metal pipe 21 connected to the tip of the metal standpipe 23 exposed to the ground via the elbow 22 is screwed into the pipe taper screw 82 of the bush 8, the exhaust operation is performed, and after the purge operation is finished, the bush 8 The purge operation in the pipe can be completed by removing the metal tube 21 and screwing a metal plug (not shown) into the tube taper screw 82 and sealing the tube.

It is sectional drawing of the cap with a purge concerning one embodiment of this invention. It is the A section expanded sectional view of FIG. It is sectional drawing which shows the state which attached the metal pipe | tube to the cap with a purge of FIG. It is sectional drawing of the cap with a purge concerning other embodiment of this invention. It is sectional drawing of the cap with a purge concerning other embodiment of this invention. It is sectional drawing which shows the state which attached the metal pipe | tube to the cap with a purge of FIG.

Explanation of symbols

1: cap with purge, 2: tubular body, 3: receiving port, 31: stepped part,
4: bottom part, 5: heating wire, 6: terminal, 7: stopper part,
8: Bush, 80: Purge port, 81: Flange, 82: Taper screw for pipe, 83: Screw, 84: Nut, 85: O-ring,
20: Resin pipe, 21: Metal pipe, 22: Elbow, 23: Stand pipe

Claims (4)

A thermoplastic resin having a receptacle into which a resin tube is inserted on one end side, a heating element for forming a fusion bonded portion with the resin tube embedded in the inner periphery of the receptacle, and a bottom portion on the other end side A purge port member made of a material made of a resin and having a pipe taper screw on the inner peripheral side at the bottom of the tubular body and made of a material having a higher mechanical strength than the resin forming the tubular body. A purged cap characterized by being secured. The purge port member is an annular body having a flange portion provided on the inner peripheral surface of the bottom portion of the tubular body on one end side, and having a screw portion having a smaller diameter than the flange portion on the outer periphery. The cap with purge according to claim 1, wherein the cap is fixed to the bottom portion by fastening a nut to the screw portion. The purged cap according to claim 1, wherein the purge port member is an annular body that is inserted when the tubular body is molded. The purged cap according to claim 1, wherein the resin pipe and the tubular body are formed of a polyolefin-based resin, and the purge port member is formed of a steel material.

Images