JPH0554884U - Pipe fitting - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent peeling or cracks in the resin lining layer that covers the inner surface of the joint body. [Structure] The pipe joint 1 includes a metal joint body 2 having tapered male screw ends 7, 7 on both the left and right sides, and a resin lining layer 4 covering an inner surface 3 of the joint body 2.
On the inner surface 3 of the joint body 2, small resin expansion / contraction groove 8 in the circumferential direction is formed at a predetermined pitch in the longitudinal direction. The lining layer 4 fills the small concave grooves 8 of the joint body 2 and forms a smooth inner surface 10. When the lining layer 4 expands or contracts due to heating or cooling, the small groove 8 ...
Since the expansion or contraction is restricted, the lining layer 4 does not peel or crack.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a pipe joint.

[0002]

[Prior Art]

 Conventionally, in a pipe joint as a nipple, 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 and b whose diameter is reduced in the distal direction, and the joint main body a. The corners d, d at the ends were covered with a resin lining layer e to prevent corrosion.

[0003]

[Problems to be solved by the device]

 However, in the conventional pipe joint as described above, the thermal expansion coefficient of the resin is larger than the thermal expansion coefficient of the metal (of the joint main body a), so that the fluid flowing in the pipe does not heat the lining layer. When the cooling is repeated, the lining layer e repeats expansion and contraction. Therefore, the lining layer e may peel off from the inner surface c of the joint body a. Further, at the time of shrinkage, the stress due to the shrinkage in the longitudinal direction may be concentrated in the portion of the resin lining layer e that covers the corners d, d of the end portion of the joint body a, and the crack f may be generated. ..

Therefore, the present invention aims to solve the above-mentioned problems and 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. And

[0005]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the pipe joint according to the present invention is a pipe joint having a male screw end portion on at least one side, and a small groove for resin expansion or contraction is formed on the inner surface of the metal joint body. A small ridge is formed at a predetermined pitch, and the lining layer that covers this inner surface fills the small groove or the small ridge, and at the same time, the inner surface of the joint main body has a plurality of resin expansion restriction small grooves or small grooves. The ridge forms a smooth inner surface and covers the corners of the end of the joint body.

[0006]

[Action]

 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, the resin expansion / contraction small groove or groove 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 restricted by the small ridges. Therefore, peeling of the lining layer is prevented. Furthermore, 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 of the end of the joint body is reduced, and cracking is prevented.

[0007]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the drawings illustrating an embodiment.

FIG. 1 shows an embodiment of a pipe joint according to the present invention. The pipe joint 1 has a left and right sides each having a tapered male screw end portion 7, 7 having a diameter reduced in the distal direction. 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. In other words, this pipe joint 1 exemplifies a case of a nipple, in which two pipes each having a female screw portion 5 at the end portion, 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 body 2 has taper-shaped male screw ends 7 1, 7 whose diameters are reduced in the front end direction on both the left and right sides. The male screw end portions 7, 7 are screwed to the female screw portions 5, 5 of the pipes 6, 6.

Further, in 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 inner surface 3 of the joint body 2 in which the small grooves 8 are formed and the corner portions 9, 9 at the left and right ends of the joint body 2 of the lining layer 4 are coated with resin by injection molding or the like. Then formed.

The resin forming the lining layer 4 may be hard resin, polyester having a high coefficient of thermal expansion, or the like, 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 end portions of the lining layer 4.

With the above-described configuration, when the pipe joint 1 according to this embodiment is in use, the lining layer 4 is not heated when the lining layer 4 is repeatedly heated and cooled due to temperature changes of the fluid flowing in the pipe. Although expansion and contraction are repeated, expansion and contraction in the longitudinal direction of the lining layer 4 is restricted at each part of the lining layer 4 that fills the small groove 8 ... No peeling occurs between the inner surface 3 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, the part that covers the corners 9, 9 of the end of the joint body 2--that is, A large load is not applied to the base end portions of the brim return portions 11, 11 to prevent the occurrence of cracks.

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

Further, FIG. 3 shows a pipe joint according to another embodiment. In this pipe joint 1, an inner peripheral surface 3 of the joint body 2 is formed with small ridges 12 ... The case where the ridges 12 ... Are filled with the liner layer 4 is shown. The small ridges 12 have the same effect as the case where the small grooves 8 are formed.

It is preferable that the small groove 8 and the small ridge 12 be formed in a continuous spiral shape instead of being formed as an independent ring. 1 to 3 illustrate the 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, but instead of this, the opening of the hole is used. It is also desirable to provide it only near the edges.

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

In addition, 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 preferable 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]

[Effect of the device]

 Since the present invention is configured as described above, it has the following effects.

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.

Particularly, it is 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 cross-sectional view showing an embodiment of a pipe joint according to the present invention.

FIG. 2 is a sectional view showing another embodiment.

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

FIG. 4 is a 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 Sekisui Chemical Co., Ltd. Shiga Ritto Plant (72) Shigeo Ueda 75 Nojiri, Ritto-cho, Kurita-gun, Shiga Sekisui Chemical Co., Ltd. Company Shiga Ritto Factory

Claims (1)

[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 metallic joint body 2, resin expansion / contraction regulating small concave grooves 8 ... Or small convex stripes 12 ... The lining layer 4 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 the end of the joint body 2 is covered with the pipe joint.