JPH063259Y2 - Anticorrosion male threaded pipe fitting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an inner surface resin-coated pipe joint in which the inner surface of a metal pipe joint body is coated with a synthetic resin. The present invention relates to an anticorrosion pipe joint configured to prevent corrosion of a portion.

[Prior Art] A connection state of a conventional screw-in type malleable cast iron pipe joint will be described with reference to FIGS. 2 to 4.

Fig. 2 shows the joint between the conventional socket 46 and bush 41.
A female screw 42 and a male screw 43 are formed on both ends of the bush 41, and the inner surface of the bush 41 is covered with a synthetic resin 44 except for the female screw 42. On the other hand, the straight pipe 15 joined to the female thread 42 of the bush 41
The inner surface of the socket and the inner surface of the socket 46 joined to the male thread 43 of the bush 41 except the female thread are also coated with the synthetic resins 16 and 48, respectively. However, each resin coating is formed only from the screw end to the edge of each member, and there is a problem that the threaded ends 49 and 55 of each joint will corrode due to water flow inside the pipe, and red water will eventually occur. .

Further, FIG. 3 shows a socket 52 that is screwed onto the entire inner surface of the plug 51.
The inner surface of is also coated with synthetic resin 53, 54 up to the screw end, but in this case as well, the screwing end 55 is exposed,
As with the above case, the screw end 55 is corroded due to water flow and red water is generated.

As a countermeasure against this, Japanese Utility Model Publication No. 60-142377 discloses an anticorrosion pipe joint shown in FIG. This is because the inner surface 5 of the joint body 21 is lined with a synthetic resin body 6 and the joint body 2
A male screw tip portion 7 made of a synthetic resin body 6 is integrally formed so as to extend to the end portion of the male screw 3 side so that the screw 3 is extended.

[Problems to be Solved by the Invention] Although the anticorrosion pipe joint shown in FIG. 4 is an excellent one as a measure against FIGS. 2 and 3, it has the following problems.

That is, when the synthetic resin body 6 is injection-molded on the inner surface of the joint body 2, the synthetic resin body 6 contracts in the radial direction and the axial direction after molding, so that a gap is formed between the inner surface 5 of the joint body and the synthetic resin body 6. Occurs. This tends to occur even when the cooling / heating cycle is repeated during use. When an abnormal pressure such as an impact pressure is applied to the pipe, the water in the pipe travels through this gap and the end of the male screw 3 of the joint and the male screw tip 7 of the synthetic resin body 6
It leaks from between. So-called back leakage occurs. Therefore, there is a problem that the inner surface of the female screw that is screwed into the male screw 3 is corroded by the leaked water.

The present invention is an anticorrosion pipe joint having a screw at one end,
An object of the present invention is to provide an anticorrosion male threaded pipe joint that suppresses shrinkage of a synthetic resin body and solves problems such as back leakage.

[Means for Solving the Problems] The gist of the present invention is to have a female screw portion on one end side of a metal pipe joint body and an annular groove on the outer peripheral surface on the other side, and to seal in the groove. A member is mounted, and the inner surface of the joint body excluding the female thread portion and the outer surface of the other side are continuously coated with a synthetic resin body by injection molding, and the one end side female thread portion of the synthetic resin body is formed. Characterized in that a cylindrical body portion having a predetermined interval is formed between the two, the synthetic resin body on the other end side extends so as to cover the sealing member, and a screw is integrally formed on the outer surface. It is a pipe joint with anti-corrosion male thread.

[Operation] As described above, according to the present invention, since the synthetic resin bodies on the inner surface and the outer surface are continuously molded, the shrinkage of the synthetic resin body is suppressed, and the gap between the joint body and the synthetic resin body is not generated. Suppress.
Especially on the outer surface side, a gap due to shrinkage is unlikely to occur. Moreover, since the sealing member is provided between them, even if a gap is created between the joint body and the synthetic resin body, the sealing member prevents water from leaking to the outside.

[Embodiment] FIG. 1 shows a bush 2 showing an embodiment of the present invention.

In FIG. 1, a taper female screw 4 having a divergent shape is formed on one end of the inner surface, and a flat portion 5 excluding the female screw 4 is covered with a synthetic resin body 6 having an appropriate thickness. Synthetic resin body 6
Is also covered from one end of the joint body 2 to the outer peripheral side from the end portion, and an O-ring 17 is attached to the joint body 2 on the outer peripheral side. The male thread 18 of the joint body 2 is formed by the synthetic resin body 6 covering the outer peripheral side. The synthetic resin body 6 is formed by injection molding a thermoplastic resin such as vinyl chloride resin, polyethylene or nylon. On the other hand, with respect to the female screw 4 side of the bush 1 in FIG. 1, when a straight pipe 15 having a synthetic resin lining 16 on the inner surface is screwed and connected, a cylindrical shape made of a synthetic resin body 6 so as to contact the inner surface of the straight pipe 15. The part 9 is formed.

Therefore, when the socket 10 having the inner surface coated with the synthetic resin is screwed into the bush 2 shown in FIG. 1 as described above, the synthetic resin body 12 coated on the inner surface between the female screws 11 at both ends of the socket 10 in advance. A gap 13 is provided at each end so as to correspond to each screw 11, and a cylindrical extension 14 is formed so that the male screw 18 formed of the synthetic resin body 6 of the bush 1 is screwed into the gap 13. The inner surface of the synthetic resin body 6 of the bush 1 is joined to the outer circumference of the cylindrical extension 14 of the socket 10. Therefore, since the male screw 18 of the bush 2 is completely formed of the synthetic resin body 6, it does not corrode, and the O-ring packing 17 is mounted between the synthetic resin body 6 and the joint body 2. Therefore, even if the synthetic resin body 6 contracts to form a gap, there is no problem that water leaks through the gap even when an abnormal pressure is applied.

[Effects of the Invention] As described above, according to the corrosion-resistant male threaded pipe joint of the present invention, the shrinkage of the synthetic resin body is suppressed to suppress the generation of the gap between the joint body and the synthetic resin body, and the sealing member is used. Since there is a complete hermetic seal between them, there is no concern about back leakage. Therefore, the joint is completely protected from corrosion, and the problem of red water generation due to corrosion can be completely eliminated.

Also, there is no need to apply any special anticorrosion treatment during construction,
There is also an advantage that construction can be done very easily.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a bush according to an embodiment of the present invention when it is connected to a straight pipe and a socket, FIG. 2 is a vertical sectional view of when a conventional bush is connected to a socket, and FIG. 3 is a conventional plug. FIG. 4 is a vertical cross-sectional view showing a case where the bush is connected to a socket, and FIG. 4 is a vertical cross-sectional view showing another conventional bush. 1 ... Plug body, 9 ... Cylindrical part, 14 ... Female thread, 2 ... Bush body, 17 ... O ring, 6 ... Synthetic resin body, 18 ... Male thread,

Claims (1)

[Scope of utility model registration request] 1. A metal pipe joint body having a female thread portion on one end side and an annular groove on the outer peripheral surface on the other side, and a sealing member is mounted in the groove to mount the female body of the joint body. The inner surface excluding the threaded portion and the outer surface on the other side are continuously covered with a synthetic resin body by injection molding, and a cylindrical shape having a predetermined interval between the one end side female threaded portion of the synthetic resin body. A body part is formed, the synthetic resin body on the other end side extends so as to cover the sealing member, and a screw is integrally formed on the outer surface of the pipe joint with an anticorrosion male screw.