JPH08338574A - Joint - Google Patents

Abstract

PURPOSE: To greatly reduce the fastening force required for attaining a complete seal in a pipe joint in which a male thread formed in a one side piece is engaged with a female thread formed in a box nut member, by forming a fluororesin layer in a part where the surface of the female thread of the box nut is engaged with the male thread. CONSTITUTION: In a pipe joint, a metal gasket 30 is interposed between a pressing surface 15 of a one side piece 10 attached to a one side pipe line 1 and a pressing surface 25 of the other side piece 20 attached to the other side pipe line 2, and by fastening a box nut member 40 having a female thread 41 engaged a male thread 11 formed on the one side piece 10 so as to connect both pipe lines with each other in a sealing manner. In this arrangement, a fluororesin layer 45 is formed on a female thread 41 so as to greatly reduce the fastening force by the box nut member 40, and to completely remove particles. During formation of the fluororesin layer 45. After degreasing, the fluororesin (for example, a solution containing ethylene tetrafluoride resin is sprayed onto the female thread 41, and is cured by heating with heat treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe joint, and is particularly used in the field of semiconductor industry where perfect sealability is required.

[0002]

2. Description of the Related Art For example, in the field of semiconductor industry such as IC and LSI, work is performed in a clean room in which particles (fine particles) are excluded, and the environment and conditions of manufacturing work are more severe.

The special gas used in this manufacturing operation is introduced from the outside of the clean room into the room through piping, but it is extremely disliked that particles and the like are mixed into the special gas.

Therefore, not only the piping but also the pipe joint for connecting the pipes to each other is required to have an extremely high precision. Further, in the case of a pipe joint such as a high pressure gas container, a perfect sealing property is required from the viewpoint of safety.

As shown in FIG. 3, a conventional general pipe joint has a pressing surface 15 of one piece 10 hermetically attached to one pipe 1 and a pressing surface of another piece 20 hermetically attached to the other pipe 2. 25, a metal gasket 30 is interposed, and the male screw 11 provided on the one piece 10 and the female screw 41 of the cap nut member 40 fitted on the other piece 20 are screwed together to rotate the cap nut member 40. Move both pieces (1
(0, 20) is tightened in the direction of the axis P to press the metal gasket 30 to seally connect both pipes (1, 2).

In order to improve the sealing performance of the above-mentioned pipe joint, the tightening force by the cap nut member 40 is increased so that the pressing surfaces (15, 25) of both pieces (10, 20) bite into the metal gasket 30 to some extent. There is a need.

Here, the male screw 1 of the one piece 10
Since No. 1 and the like are completely degreased to remove particles, the female screw 41 is silver-plated so that the female screw 41 is not galled when tightened with the cap nut member 40.

That is, the female screw 41 of the cap nut member 40
First, as shown in FIG. 4, after degreasing (A′1), copper plating (A′2), nickel plating (A′3) and silver plating (A′4) are performed. The cap nut member 40 is barrel-polished to form an internal thread 41 for the sake of appearance.
The silver plating on the outer surface except for is peeled off.

[0009]

By the way, in the above-mentioned conventional pipe joint, in order to achieve a perfect seal, the cap nut member 40 is rotated by a wrench or the like to rotate both pieces (10, 2).
0) is a strong force (eg, 270 to 350 kgf · cm)
However, it may be difficult for the worker to tighten with a strong force depending on the piping location, so improvement is strongly required from the viewpoint of workability.

When the cap nut member 40 is rotated to strongly tighten both pieces (10, 20), a female screw 41 is formed.
There may be a fatal situation in which a part of the silver plating is peeled off and becomes particles to be mixed into the gas flow paths of the pipes (1, 2).

In view of the above circumstances, an object of the present invention is to provide a pipe joint which can greatly reduce the tightening force required to achieve a perfect seal and can completely eliminate particles. It is in.

[0012]

SUMMARY OF THE INVENTION According to the present invention, a male screw provided on one piece and a female screw of a cap nut member fitted on the other piece are screwed together, and the cap nut member is rotated to rotate the one piece. In the pipe joint for sealingly connecting both pieces by pressing the gasket interposed between the two pieces by tightening the other piece and the other piece, at least a portion of the female thread surface of the cap nut member that is screwed with the male thread. It is characterized in that a fluororesin layer is formed.

[0013]

In the present invention having the above-described structure, when the cap nut member is rotated by tightening the female screw of the cap nut member and the male screw of the one piece to tighten the one piece and the other piece, the male screw of the female screw is formed. Since the fluororesin layer is formed in the portion to be screwed with, the frictional force generated between both screws is greatly reduced as compared with the conventional silver plating.

Therefore, the tightening force required to achieve a perfect seal can be greatly reduced. In addition, since the fluororesin layer adheres strongly to the female screw surface and it is not necessary to increase the tightening force as described above, it will not be separated during tightening and will enter the gas flow path in the pipe as particles. It doesn't get lost.

Therefore, the tightening force required to achieve a perfect seal can be greatly reduced, and particles can be completely eliminated.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, the present pipe joint has the same basic structure as the conventional example (FIG. 3), but the internal thread 41 of the cap nut member 40 is provided with a fluororesin layer 45, and the cap nut is The member 40 is configured to be able to significantly reduce the tightening force and completely eliminate particles.

The same components as those of the conventional example (FIG. 3) are designated by the same reference numerals, and the description thereof will be simplified or omitted.

Fluorine resin layer 45, which is a feature of the present invention
Is a portion of the surface of the female screw 41 of the cap nut member 40 that is screwed with at least the male screw 11 [in FIG. 1 (A), length L1].
[Range part]. In this embodiment, the fluororesin layer 45 is formed on the entire surface of the female screw 41 [the portion of the length L range in the figure].

That is, the female screw 41 of the cap nut member 40.
As shown in FIG. 2, first, a degreasing treatment (A1) is performed, and then a fluorine resin (for example, a liquid containing a tetrafluoroethylene resin) is sprayed (A2) using a spray or the like. After spraying, it is heat treated (A3) and heat-cured. As a result, as shown in FIG. 1 (B), the surface of the female screw 41 has a predetermined thickness (for example, 8 to 15 μm) with a slippery feeling and low friction.
The fluororesin layer 45 of m) is formed.

Here, the liquid containing the tetrafluoroethylene resin becomes a semi-glossy, hard film after heat curing.
It has excellent bending resistance and impact resistance. The coefficient of static friction is as small as 0.06 to 0.08.

In FIG. 1 (A), 8 is a thrust bearing, which is interposed between the inner surface of the cap nut member 40 and the other piece 20 as a means for transmitting axial force but not rotational force. There is. As a result, both pieces (10, 2
0) and the metal gasket 30 can be secured with a tightening force of a certain value or more without causing torsional deformation.

With the above structure, the female screw 41 of the cap nut member 40 and the male screw 11 of the one piece 10 are screwed together, and in that state, the cap nut member 40 is rotated using a wrench or the like to rotate the one piece 10 and the other piece. The frictional force generated between both screws (11, 41) when tightening 20 and 20 is greatly reduced by the fluororesin layer 45 as compared with the conventional case. for that reason,
Small tightening force (for example, 135 to 160 kgf · cm)
Thus, the metal gasket 30 can be pressed sufficiently to achieve a perfect seal.

In this way, the tightening force can be greatly reduced compared to the conventional case, so that a perfect seal can be achieved even if the main fitting is arranged at a high place and tightening is difficult. Further, since the fluororesin layer 45 is firmly adhered to the surface of the female screw 41, a part of the fluororesin layer 45 is peeled off at the time of tightening and the pipe (1, 2 ) It doesn't get mixed in.

Therefore, the tightening force required to achieve a perfect seal can be greatly reduced and particles can be completely eliminated.

Further, the conventional silver plating has the same luster as the surface of the cap nut member 40 formed of stainless steel or the like, and it is possible to visually confirm whether or not the silver is plated and the quality of the silver plating. It was very difficult to do this, but the fluororesin layer 45
Since the latter has a gloss after heat curing, it is possible to easily visually confirm whether the fluororesin layer 45 is formed on the female screw 41, its quality and the like.

The fluororesin layer 45 may be colored by adding a pigment paste to a liquid containing an ethylene tetrafluoride resin. As a result, the presence or absence of the formation of the fluororesin layer 45, the quality, and the like can be more easily visually confirmed.

In the above embodiment, the fluororesin layer 45 is used.
Was formed using an ethylene tetrafluoride resin, but it may be formed using a fluorine resin other than this.

[0028]

According to the present invention, since the fluororesin layer is formed on at least the portion of the female screw surface of the cap nut member that engages with the male screw, the tightening force required to achieve a perfect seal can be obtained. It can be greatly reduced and particles can be eliminated completely.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an example of the present invention.

FIG. 2 is likewise a diagram for explaining a process for forming a fluororesin layer.

FIG. 3 is a diagram for explaining a conventional configuration of a pipe joint.

FIG. 4 is also a diagram for explaining the step of silver plating the female thread of the cap nut member.

[Explanation of symbols]

 10 One Piece 11 Male Thread 20 The Other Piece 30 Metal Gasket 40 Cap Nut Member 41 Female Thread 45 Fluororesin Layer

Claims (1)

[Claims] 1. A male screw provided on one piece and a female screw of a cap nut member fitted on the other piece are screwed together, and the cap nut member is rotated to tighten the one piece and the other piece. In a pipe joint for sealingly connecting both pieces by pressing a gasket interposed between both pieces, a fluororesin layer is formed on at least a portion of the female screw surface of the cap nut member that is screwed with the male screw. A characteristic pipe joint.