JP2515539Y2 - Pipe fitting - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe joint.

[0002]

2. Description of the Related Art Conventionally, in a pipe joint as a nipple, as shown in FIG. 4, generally, as shown in FIG. 4, a peripheral wall inner surface c of a substantially cylindrical joint main body a having tapered male screw portions b, b The corners d, d at the end of the joint body a were covered with a resin lining layer e to prevent corrosion.

[0003]

However, in the conventional pipe joint as described above, the coefficient of thermal expansion of the resin is (the joint body a
Since the coefficient of thermal expansion of the metal is larger than that of the metal, the lining layer e repeats expansion and contraction in a situation where heating and cooling of the lining layer are repeated by the fluid flowing in the pipe. For this reason, the lining layer e may peel from the inner surface c of the joint body a. Further, at the time of contraction, the corners d, d of the end of the joint body a in the resin lining layer e
In some cases, the stress due to the contraction in the longitudinal direction was concentrated on the portion that covered the, and the crack f was generated.

Therefore, the present invention solves the above-mentioned problem,
An object of the present invention is to provide a pipe joint in which peeling or cracking does not occur in the lining layer covering the inner surface of the joint body and the corners of the ends.

[0005]

In order to achieve the above-mentioned object, a pipe joint according to the present invention is a pipe joint having a male screw end portion on at least one side.
Small recessed grooves or small ridges for resin expansion and contraction are formed at a predetermined pitch, and the lining layer that covers this inner surface fills the small recessed grooves or the small ridges, and on the inner surface of the joint body, a plurality of resin A small concave groove for expansion and contraction or a small convex line forms a smooth inner surface and covers the corner portion of the end of the joint body.

[0006]

When the lining layer expands or contracts due to repeated heating and cooling of the lining layer due to the fluid flowing in the pipe during use, a small resin expansion / contraction regulating resin formed on the inner surface of the joint body at a specified pitch. Expansion and contraction in the longitudinal direction of the lining layer are regulated by the groove or the small ridge.
Therefore, peeling of the lining layer is prevented. Further, since the shrinkage of the lining layer is regulated, the load due to the shrinkage in the portion of the lining layer that covers the corner portion of the end of the joint body is reduced, and the occurrence of cracks is prevented.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings showing an embodiment.

FIG. 1 shows an embodiment of a pipe joint according to the present invention. This pipe joint 1 has a left and right sides each having a tapered male screw end portion 7, 7 having a tapered diameter. A cylindrical metal joint body 2 and a resin lining layer 4 that covers the inner surface 3 of the peripheral wall of the joint body 2 are provided. That is, this pipe joint 1 exemplifies a case of a nipple, and two pipes having a female screw portion 5 at the end which is reduced in diameter toward the inside of the opening and into which the male screw end portion 7 of the joint body 2 is screwed. 6, 6 are connected.

The joint main body 2 has tapered male screw end portions 7, 7 on both the left and right sides, the diameters of which are reduced in the tip direction.
The male screw end portions 7, 7 are screwed to the female screw portions 5, 5 of the pipes 6, 6.

Further, on the inner surface 3 of the peripheral wall of the joint body 2, small resin expansion / contraction recessed grooves 8 ... Are formed in the circumferential direction at a predetermined pitch in the longitudinal direction. The small grooves 8 ... Have a substantially triangular cross section and an independent annular shape.

The lining layer 4 is formed by the joint body 2
The inner surface 3 in which the small concave grooves 8 ... Are formed and the corner portions 9 at the left and right ends of the joint body 2 are formed by coating resin by injection molding or the like.

The resin forming the lining layer 4 may be hard resin or polyester having a large coefficient of thermal expansion, and other resins may be used freely.

The lining layer 4 thus fills the small grooves 8 of the joint body 2 and forms a smooth inner surface 10. Further, flanged portions 11 that cover the left and right end surfaces of the joint body 2 are formed at the left and right ends of the lining layer 4.

With the above structure, the pipe joint 1 of this embodiment
In a situation where the lining layer 4 is repeatedly heated and cooled due to temperature changes of the fluid flowing in the pipe in the use state of 1, the lining layer 4 repeatedly expands and contracts, but the small groove 8 of the joint body 2 ... Since the expansion and contraction of the lining layer 4 in the longitudinal direction is restricted in each part of the lining layer 4 which fills the inner wall of the joint body 2, peeling does not occur between the inner surface 3 of the joint body 2 and the lining layer 4. .

Furthermore, since the contraction of the lining layer 4 in the longitudinal direction is restricted, when the lining layer 4 contracts,
A large load is not applied to the end portions of the joint body 2 that cover the corner portions 9, 9, that is, the base end portions of the collar return portions 11, 11 and cracks can be prevented from occurring.

Next, FIG. 2 shows a pipe joint of another embodiment. In the pipe joint 1, the small concave grooves 8 ... Of the joint body 2 are square grooves.

Further, FIG. 3 shows a pipe joint of another embodiment. In this pipe joint 1, an inner peripheral surface 3 of the joint main body 2 is formed with small ridges 12 ... The case where the ridges 12 ... Are filled with the lining layer 4 is shown. This is a small ridge 12.
According to this, the same effect as in the case of forming the small groove 8 ...

The small groove 8 and the small ridge 12 ...
It is also preferable to form a continuous spiral without forming an independent ring. In addition, although FIGS. 1 to 3 exemplify a case where the small groove 8 or the small ridge 12 is provided over the entire length of the inner surface of the joint body 2, instead of this, in the vicinity of the opening end of the hole. It is also desirable to provide only.

Further, in the above embodiment, the case of the nipple was illustrated, but it is also preferable to have a male screw end portion 7 on only one side (bush).

Further, in the nipple of FIGS. 1 to 3, it is of course preferable to shorten the intermediate portion--the portion other than the male screw end portions 7 and 7--to have a hexagonal outer shape or the like ( (Not shown). It is also desirable that the small grooves 8 have a semicircular cross section, and the small ridges 12 have a triangular cross section or a semicircular cross section.

[0021]

Since the present invention is configured as described above,
The following effects are obtained.

It is possible to prevent peeling between the inner surface 3 of the joint body 2 and the lining layer 4, and to cover the corner 9 of the end of the joint body 2 in the lining layer 4.
It can prevent peeling and cracking.

This is particularly effective when the lining layer 4 is formed of a hard resin or polyester having a large coefficient of thermal expansion.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a pipe joint according to the present invention.

FIG. 2 is a cross-sectional view showing another embodiment.

FIG. 3 is a cross-sectional view showing another embodiment.

FIG. 4 is a cross-sectional view of a main part showing a conventional example.

[Explanation of symbols]

 2 Joint body 3 Inner surface 4 Lining layer 7 Male screw end 8 Small groove 9 Corner 10 Inner surface 12 Small ridge

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takao Miyake 75 Nojiri, Ritto-cho, Kurita-gun, Shiga Prefecture Sekisui Chemical Co., Ltd., Shiga Ritto Plant (72) Shigeo Ueda 75 Nojiri, Ritto-cho, Kurita-gun, Shiga Sekisui Chemical Co., Ltd. Co., Ltd. Shiga Ritto Factory

Claims (1)

(57) [Scope of utility model registration request] 1. A pipe joint having a male screw end portion 7 on at least one side thereof, on the inner surface 3 of a metal joint body 2, resin expansion / contraction regulating small concave grooves 8 ... Or small convex stripes 12 ... The lining layer 4 which is formed by covering the inner surface 3 fills the small groove 8 or the small ridge 12 and has a smooth inner surface 10.
And a corner portion 9 at an end portion of the joint body 2 is covered with the pipe joint.