JPH0616198Y2 - Non-leak fitting - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a pipe joint without leakage from a connecting portion, and more particularly to a pipe joint suitable for an apparatus using ultra-high vacuum. is there.

[Prior Art] A conventionally known pipe joint includes a pair of flanges having a tube, a gasket, and a cap nut screwed to one of the flanges, and presses the flange by screwing the cap nut to the flange. The gasket between the flanges is clamped to seal the connection.

This known pipe joint, even if it is possible to improve the finish of the pair of flanges and the respective contact surfaces of the cap nut and the gasket as much as possible, it is inevitable that a minute rotational distortion will occur in the gasket when the cap nut is screwed. This distortion causes a leak,
In addition, even if no leakage occurs during the initial screwing, when disassembled and reassembled, leakage may occur due to residual strain.

Therefore, the above-mentioned known pipe joint cannot meet the demand of an apparatus using ultra-high vacuum that requires a high level of sealing performance that cannot be detected by a mass spectrometer (helium leak detector).

In addition, a pipe joint in which a convex portion and a concave portion in the circumferential direction are provided on the opposing surfaces of a pair of flanges, and the rotational distortion of the gasket due to the screwing of the cap nut is eliminated by fitting the convex portion and the concave portion is a
-94784 publication.

However, this previously proposed pipe joint has a problem that the processing of the convex portion and the concave portion provided on the facing surfaces of the pair of flanges is troublesome and the cost is high.

[Problems to be Solved by the Invention] The problem to be solved by the present invention is to provide a pipe joint that is leak-free and inexpensive.

[Means for Solving Problems] In order to solve the above problems, the non-leak joint of the present invention is
A pipe joint that includes a pair of flanges having tubes, a gasket, and a cap nut that is screwed into one of the flanges, and that presses the gasket between the flanges by screwing the cap nut into the flange to seal the connection portion. In the above, one of the flanges is provided with a recess into which the other of the flange is inserted, and both ends of the recess, which are formed on the end surface of the peripheral wall of the recess, have radial engagement grooves that open to the inner and outer surfaces of the peripheral wall. A plate having an engaging piece fitted into the engaging groove is provided between the other and the cap nut.

[Operation] When the cap nut is screwed into one of the flanges, the gasket is pinched by the pair of flanges to seal the connection portion.

In this case, the rotational force acts on the other flange due to the screwing of the cap nut, but the plate provided between the cap nut and the other flange does not rotate by engaging the engaging groove, so the flange and the gasket are not rotated. Only thrust in the axial direction acts on.

Therefore, not only is it possible to prevent leakage due to the rotation of the flange and the gasket, but there is no residual strain.
It is also possible to prevent leakage due to re-assembly.

Further, the engagement groove and the engagement piece for preventing the rotation of the flange and the gasket can be easily processed.

[Embodiment] FIGS. 1 to 3 show an embodiment of the present invention. This non-leak pipe joint includes a male flange 1, a cap nut 2 screwed to the male flange, and a flange 3 inserted into the male flange 1. ,
Plate 4 between flanges 1 and 3 and cap nut 2 and flange
It is equipped with a gasket 5 which is pinched by 1,3.

The male flange 1 has a tube 7 welded or integrally formed at one end, a groove 8 on the bottom surface of the recess 1a in which the gasket 5 is mounted, and both ends of the end surface of the peripheral wall 9 of the recess 1a. Radial engagement grooves 1b, 1 open on the inner and outer surfaces of the peripheral wall 9
b), the tube-side base 10 has a hexagonal shape, and a male screw is engraved on the outer circumference.

The flange 3 has a tube 12 welded or integrally formed at one end, and the same groove 8 as the groove 8 is formed on the end face to be inserted into the recess 1a, and the plate 4 can be inserted into the recess 1a. Engaging pieces 4a, 4a having different outer diameters and engaging and engaging with the engaging grooves 1b, 1b are formed on the outer periphery.

The flanges 1 and 3 and the plate 4 are attached to the plate 4 before and after the cap nut 2 is screwed onto the male flange 1.
Is abutted on the flange 3 and the engaging pieces 4a of the engaging pieces 4a are associated with the engaging grooves 1b, 1b.

In order to prevent the plate 4 from falling off during assembly, the spring pieces 14, 14 may be integrally formed as shown in FIG. 4, or as shown in FIG. It is also possible to form a locking piece with a plurality of notches 15, ... And to lock this into a groove (not shown) provided in the base of the tube 12.

The gasket 5 has a circular cross section, has a spring inside, and is constituted by what is called a helicolex, which is sealed by a jacket whose surface is mirror-finished, but can be a C ring.

The cap nut 2 is composed of a normal cap nut having a top wall having a hole into which the tube 12 is loosely inserted and a hexagonal outer peripheral wall in which a female screw to be screwed into the screw of the male flange 1 is engraved. .

Then, the inner surface of the top wall of the cap nut 2, the contact surface of the male flange 1 with the gasket 5, and the both surfaces of the flange 3 and the plate 4 are subjected to a low friction treatment such as mirror finishing.

In the above embodiment, the gasket 5 is provided in the groove 8 of the male flange 1,
The flange 3 is inserted into the recess 1a, the engaging pieces 4a, 4a of the plate 4 are fitted into the engaging grooves 1b, 1b of the male flange 1, the base 10 of the male flange 1 is held, and the cap nut 2 is screwed. By doing so, the flanges 1 and 3 press the gasket 5 to seal the connection portion.

In this case, by screwing the cap nut 2 into the male flange 1,
A rotational force and an axial thrust force act on the plate 4, but since the locking pieces 4a, 4a of the plate 4 engage with the engagement grooves 1b, 1b and do not rotate, the flange 3 has only the axial thrust force. Works.

Therefore, since the rotational force is not transmitted to the gasket 5, it is possible to prevent leakage due to minute rotational distortion of the gasket and leakage due to residual distortion under ultrahigh vacuum.

Further, the engaging grooves 1b, 1b are formed by grooves that open on the inner and outer surfaces of the end face of the peripheral wall 9, and engaging pieces 4a, 4a engaging with the engaging grooves 1b, 1b are provided on the plate 4. Therefore, these processes are extremely easy to perform, and the pipe joint that can prevent leakage can be made inexpensive.

[Advantages of the Invention] In the pipe joint of the present invention, due to the engagement between the engagement groove and the engagement piece of the plate, the rotational force generated by the screwing of the cap nut is not transmitted to the flange, so that a minute rotational distortion or Since there is no residual crack, it is possible to completely prevent leakage of the pipe joint.

Further, it is extremely easy to process the engaging groove that opens on the inner and outer surfaces of the end face of the peripheral wall and the engaging piece provided on the plate, and the material is wasted because the engaging piece is provided on the plate which is separate from the flange. Therefore, a pipe joint that can completely prevent leakage can be made inexpensive.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a vertical sectional front view, FIG. 2 is a plan view of a male flange, FIG. 3 is a plan view of a plate, and FIGS. 4 and 5 are modification examples of the plate. It is a top view. 1 ... Male flange, 1a ... Recess, 1b ... Engagement groove, 2 ... Cap nut, 3 ... Flange, 4 ... Plate, 4a ... Engaging piece, 5 ... Gasket, 7, 12 ... … Tube, 9 …… peripheral wall.

Claims (1)

[Scope of utility model registration request] 1. A pair of flanges each having a tube, a gasket, and a cap nut screwed to one of the flanges. The cap nut between the flanges is screwed to the flange so as to clamp the gasket between the flanges. In the pipe joint that seals, one of the flanges has a recess into which the other of the flange is inserted, and both ends of the recess formed in the end surface of the peripheral wall of the recess have radial engagement grooves that open to the inner and outer surfaces of the peripheral wall. A non-leak pipe joint characterized in that a plate having an engagement piece fitted into the engagement groove is provided between the other of the flanges and the cap nut.