JPH0410467Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a pipe joint, and more specifically, to a pipe joint suitable for equipment using ultra-high vacuum that requires ultra-hermetic sealing. .

[Prior Art] A known pipe joint includes a seal bolt, a seal tube, a gasket, and a cap nut, and the cap nut is screwed onto the seal bolt to squeeze the gasket between the seal bolt and the seal tube to create a connection. is sealed.

And super airtight (usually helium leak crate)
10 ^-10atm cc/SEC or less. ), a metal gasket such as a metal C-ring or a metal flat gasket with a mirror-finished sealing surface is used.

In this case, if torque is applied to these metal gaskets by tightening the cap nut, the sealing surface will be scratched and this scratch will cause leakage, so the cap nut and seal tube should be carefully connected to prevent the seal tube from rotating. A bearing is installed between the seal tubes, but if this bearing moves in the axial direction of the seal tube, there is a problem that if the cap nut is oriented sideways or downwards, the bearing will move, making it difficult to work.

Metal flat gaskets have the advantage of being cheaper than metal C-rings (approximately 1/10 the cost for a 30mm diameter), but aluminum gaskets have lower hardness and elasticity than seal bolts and seal tubes.
Since it is made of a material such as copper or silver, there is a problem that creep due to tightening is relatively large, and the initial repulsion force decreases due to long-term use or baking.

For this reason, conventionally, bearing holding means,
A separate means is provided to compensate for the reduction in the repulsive force of the flat metal gasket, but this not only increases the number of parts but also makes assembly difficult.

[Problem to be solved by the invention] The problem to be solved by the invention is to improve assembly by using a single part to hold the thrust bearing and compensate for the reduction in the repulsive force of the flat metal gasket. Another object of the present invention is to provide a super airtight pipe joint that is easy to maintain.

[Means for Solving the Problems] In order to solve the above problems, the super airtight pipe joint of the present invention includes a seal bolt, a seal tube, a metal flat gasket, and a cap nut, and the cap nut is screwed into the seal bolt. In a pipe joint that seals a connection by pinching a metal flat gasket with a mirror-finished sealing surface between a seal bolt and a seal tube, the seal tube is attached to a cap nut on the seal tube side between the seal tube and a cap nut. A thrust bearing that prevents the transmission of torque to the seal tube, and a disc spring fastener on the cap nut side that holds the thrust bearing and compensates for the repulsive force of the flat metal gasket with its axial elasticity. It is characterized by the presence of

[Function] The disc spring fastener attached to the cap nut side of the seal tube holds the thrust bearing on the seal tube side, absorbs minute dimensional differences in the flat metal gasket with its axial elasticity, and has a long lifespan. If the initial repulsive force of the metal flat gasket decreases due to the use of
You can make up for it.

Therefore, assembly and maintenance of the super-hermetic pipe joint is easy.

[Example] Figures 1 to 4 show examples of the present invention,
This super-airtight pipe joint 1 includes a seal bolt 2, a cap nut 3 screwed onto the seal bolt 2, a seal tube 4, a flat metal gasket 5 which is pressed between the seal bolt 2 and the seal tube 4, and is attached to the seal tube 4. It is equipped with a thrust bearing 6 and a disc spring fastener 7.

The seal bolt 2 has a tube 8 welded or integrally formed at its base end, an edge-shaped seal portion 9 on the other end of which the flat metal gasket 5 abuts, and a pair of axially protruding portions on the outside of the seal portion 9. A locking groove 1 for locking a retaining ring 11 on the inner surface of the holders 10, 10.
2 and 12, the base 2a on the tube side has a hexagonal outer shape, and a male thread is carved on the outer periphery.
Further, the seal tube 4 has an edge-shaped seal portion 15 opposite to the seal portion 9 formed on a flange 14 welded or integrally formed at the tip thereof, and has a circumferential groove 16 on the outer periphery in which the disc spring fastener 7 engages. We are prepared.

The cap nut 3 includes a top wall 3a having a hole that is loosely inserted into the seal tube 4, and a peripheral wall having a hexagonal outer shape and having a female thread that is screwed into the seal bolt 2.
A non-slip ring 17 is provided in the groove of the top wall 3a, and a plurality of protrusions 17a formed on the non-slip ring 17,
... (see Fig. 3), it is attached to the seal tube 4 so as not to slip in the axial direction.

The metal flat gasket 5 has seal parts 9, 1
The retaining ring has a mirror-finished sealing surface facing 5, has a groove 5a on its outer peripheral surface in which the retaining ring 11 is engaged, and has a diameter that engages in the groove 5a and the retaining grooves 12, 12. 11 to the seal bolt 2. Therefore, even if the seal portion is oriented sideways or downward, the gasket 5 will not fall off the seal bolt 2.

When the cap nut 3 is screwed onto the seal bolt 2, the thrust bearing 6 prevents the transmission of torque to the seal tube 4 as much as possible to prevent scratches on the mirror-finished seal surface of the metal flat gasket 5. It is attached to the seal tube 4 by a disc spring fastener 7. This disc spring fastener 7 includes a side wall 7a, a curved bottom wall 7b, and claws 19, . . . formed by radial notch grooves 18, . It was attached to the seal tube 4 by engaging the pawls 19, . Sometimes it provides elasticity in the axial direction.

In the above embodiment, when the cap nut 3 is screwed onto the seal bolt 2, the seal parts 9 and 15 pinch the flat metal gasket 5 and seal the connection part. In this case, the metal flat gasket 5 is connected to the locking grooves 12, 12.
The seal bolt 2 is secured by the retaining ring 11 that is locked to the
Furthermore, since the thrust bearings 6 are each held on the seal tube 4 by the disc spring fasteners 7, they will not fall off the seal bolt 2 even if the seal portion is oriented sideways or downwards. Therefore, the work of tightening the pipe joint is extremely easy.

Further, since an elastic force in the axial direction is applied to the seal tube 4 by the disc spring fastener 7 interposed between the seal tube 4 and the cap nut 3, the metal flat gasket 5 can be damaged by long-term use or baking. Even if the repulsive force decreases, a nearly constant clamping force is still acting between the seal parts 9 and 15 due to the elasticity of the disc spring fastener 7, so it is necessary to retighten the cap nut 3. do not have.

Therefore, the disk spring fastener 7 can hold the thrust bearing 6 and compensate for the decrease in the repulsive force of the flat metal gasket 5, making assembly and maintenance of the super airtight pipe joint 1 extremely easy. It is.

[Effects of the invention] The super airtight pipe joint of the invention uses a disc spring fastener provided between the seal tube and the cap nut to hold the thrust bearing and compensate for the reduction in repulsive force of the flat metal gasket. Therefore, assembly and maintenance of the super airtight pipe joint is extremely easy.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of an embodiment of the present invention, Fig. 2 is an enlarged longitudinal sectional view of its main parts, Fig. 3 is a side view of the anti-slip ring, and Fig. 4 is a side view of the disc spring fastener. . 1...Super airtight pipe fitting, 2...Seal bolt, 3
...Bag nut, 4...Seal tube, 5...Metal flat gasket, 7...Disc spring fastener.

Claims (1)

[Claims for Utility Model Registration] A seal bolt, a seal tube, a flat metal gasket, and a cap nut are provided, and by screwing the cap nut onto the seal bolt, the sealing surface between the seal bolt and the seal tube is a mirror-finished metal flat gasket. In a pipe fitting that seals a connection by compressing a gasket, the seal tube has a thrust bearing between the cap nut and the cap nut that prevents torque from the cap nut from being transmitted to the seal tube. A super airtight pipe joint characterized by comprising a disc spring fastener on the side that holds the above-mentioned thrust bearing and compensates for the repulsive force of the flat metal gasket with elasticity in the axial direction.