JP2542174Y2 - Pipe fittings - Google Patents

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 more particularly to a pipe joint having improved sealing performance between a thin metal pipe and a joint body.

[0002]

2. Description of the Related Art In general, a pipe joint for connecting thin metal pipes used for low pressure fluid pipes or the like is known (for example, Japanese Utility Model Application Laid-Open No. 58-132284).

[0003] As shown in FIG. 3, this type of device comprises a union 31 and a nut 33, and a thin metal tube 35 is fixed to the union 31. A thin-walled metal pipe 37 to be connected to the pipe 35 is formed with a tapered portion 37a at the tip end thereof. The tapered portion 37a is formed by a tip inclined surface 31a of the union 31 and an inner peripheral inclined surface of the nut 33. The pipe 37 and the pipe joint are connected by clamping the union 31 and the nut 33 between the pipe 37 and the pipe 33.

[0004]

However, in the above-mentioned conventional technique, the tapered portion 37a of the pipe 37 is a so-called sealing surface, and the tapered portion 37a and the tip inclined surface 3 are formed.
1a, and the taper angle between the tapered portion 37a and the inner peripheral inclined surface 33a tends to vary in processing, so that
There is a problem that the taper angles of the parts tend to be inconsistent, and the sealing performance of the pipe joint is impaired. Further, in handling, if the inner surface of the tapered portion 37a of the pipe 37 or the tip inclined surface 31a of the union 31 is damaged, there is a problem that the sealability of the pipe joint is further impaired.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a pipe joint having improved sealing performance.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention forms an expanded portion having an inner diameter larger than the inner diameter of the tube at the end of the tube, and forms a bag-shaped outer periphery of the expanded portion. While fitting the nut, the joint body is inserted so that the outer periphery of the distal end portion is in contact with the inner periphery of the expanded portion via a seal member, and the female screw of the bag-shaped nut is screwed into the outer thread of the joint body. And connecting the pipe and the joint body.

[0007]

With this construction, the outer peripheral surface of the pipe does not become a so-called sealing surface. Therefore, even if the outer diameter of the pipe varies during manufacturing, the sealing performance of the pipe joint is impaired. Never. According to this configuration, the so-called sealing surface is the inner peripheral surface of the expanded portion of the pipe. Since the inner peripheral surface dimension of the expanded portion can be finished with extremely high precision, the variation in the size is small, and the sealing performance between the joint body and the expanded portion can be remarkably improved.

[0008]

FIG. 1 shows an embodiment of a pipe joint according to the present invention.
This will be described with reference to FIG.

In FIG. 1, reference numeral 1 denotes a thin metal pipe used for a low pressure fluid pipe or the like. The tube 1 has an inner diameter d, and an expanded portion 3 having an inner diameter D larger than the inner diameter d of the tube 1 is formed at an end of the tube 1. Further, a tapered receiving port 3a is formed at the tip of the expanded tube portion 3 so as to expand forward. Here, when the thin metal pipe 1 is expanded, it is performed by a special inner diameter expansion tool, so that the dimension of the inner diameter D of the expanded portion 3 can be extremely accurately finished.

A sack-shaped nut 5 is fitted around the outer periphery of the expanded portion 3. The bag-shaped nut 5 has a large opening slightly larger than the outer diameter D ₁ of the expanded portion 3, of which the circumference has female thread 5a is engraved, the peripheral wall of the openings, the expanded pipe portion 3 leading end of the It is configured to be locked on the outer surface of the receptacle 3a.
The distal end 9 of the joint body 7 is inserted into the inner periphery of the expanded tube portion 3, and a ring groove extending in the circumferential direction is formed on the outer periphery of the distal end 9. A seal member 11 is fitted into the ring groove, and the outer periphery of the distal end portion 9 of the joint body 7 and the inner periphery of the expanded portion 3 are hermetically sealed via the seal member 11.

Further, a receiving port 3 is provided at the distal end 9 of the joint body 7.
a step 9a is formed on the inner surface of the step 9a.
From the boundary, a male screw 13a is engraved on the outer periphery of the enlarged diameter portion 13 of the joint main body 7 that is not inserted into the expanded tube portion 3. According to this embodiment, after the distal end 9 of the joint body 7 is inserted into the inner periphery of the expanded portion 3 of the thin-walled metal pipe 1, the cap nut is attached to the external thread 13a of the outer periphery of the joint body 7. The fifth female screw 5a is screwed together to connect the pipe 1 to the joint body 7.

With this configuration, the outer peripheral surface of the original pipe of the pipe 1 does not necessarily serve as a sealing surface. Therefore, even if the outer diameter of the pipe 1 varies at the time of manufacturing, the sealing performance of the pipe joint can be improved. Is not impaired. According to the configuration of this embodiment, the so-called sealing surface is the inner peripheral surface of the expanded portion 3 of the pipe 1. Since the inner peripheral surface dimension of the expanded portion 3 can be finished with extremely high precision as described above, the variation in the size is reduced, and the sealing property between the joint body 7 and the expanded portion 3 is smaller than that of the conventional one. Can be significantly improved. Also, in handling, the outer peripheral surface and the end of the tube 1 are easily scratched, but according to this, the outer peripheral surface and the end of the tube 1 do not become a sealing surface. However, the sealability of the pipe joint is not impaired.

According to this embodiment, the receiving port 3 of the pipe 1 is also provided.
Since a is locked to the peripheral wall of the opening of the bag-shaped nut 5, the pipe 1 does not come off from the pipe joint. In addition, since connection cannot be made unless the end of the pipe 1 is expanded at the time of connection, an erroneous construction method can be reliably prevented.

FIG. 2 shows another embodiment. According to this, the peripheral wall of the opening of the bag-shaped nut 5 is formed by the stepped portion 3 of the expanded portion 3.
b, and the expanded portion 3 is not formed with the receiving port 3a as in the above embodiment. According to this, since the peripheral wall of the opening of the bag-shaped nut 5 locks the step portion 3b of the expanded portion 3 of the pipe 1, it is possible to reliably prevent the pipe 1 from coming out of the pipe joint.

If the expansion of the pipe 1 is insufficient, the pipe 1 cannot be fitted to the distal end portion 9 of the joint body 7, so that a leak occurs at the time of the water pressure test at the end of the pipe, and an abnormality is found. Therefore, an erroneous construction method can be reliably prevented.

[0016]

As is apparent from the above description, according to the present invention, an expanded part having an inner diameter larger than the inner diameter of the pipe is formed at the end of the pipe, and a cap nut is formed on the outer circumference of the expanded part. While inserting the joint body so that the outer periphery of the distal end portion is in contact with the inner periphery of the expanded portion via a seal member, and screwing the female screw of the cap nut into the external thread of the joint body. Since the pipe and the joint body are connected, the inner peripheral surface of the expanded portion of the pipe becomes a so-called sealing surface, so that the sealing performance of the pipe joint can be remarkably improved.

[Brief description of the drawings]

FIG. 1 is a 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 sectional view showing a conventional pipe joint.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tube 3 Expanding part 3a Receptacle 5 Bag-like nut 5a Female thread 7 Joint body 11 Sealing member 13 Large diameter part 13a Male screw

Claims (1)

(57) [Scope of request for utility model registration] An expanded tube having an inner diameter larger than the inner diameter of the tube is formed at an end of the tube, and a sack-shaped nut is fitted around the outer periphery of the expanded tube. Insert the joint body so that the outer circumference contacts with the seal member,
A pipe joint, wherein the female thread of the bag-shaped nut is screwed into an external thread of the joint body to connect the pipe to the joint body.