JP2562757Y2 - Fittings for stainless steel pipes - 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 suitable for connecting a thin stainless steel pipe.

[0002]

2. Description of the Related Art Conventionally, there is a pipe joint shown in FIG. 3 disclosed in Japanese Utility Model Publication No. 56-7182. This presses the end 7 of the tube 6 expanded in a trumpet shape against the taper outer surface 3 of the joint body 1 with the taper inner surface 5 of the cap nut 4 via the gasket 2, and -Sealing of the fluid in the pipe by the gasket 2 sandwiched between the outer surface 3 of the pad and the end 7 of the pipe. With respect to the taper angle at which the end of the pipe is expanded in a trumpet shape, in the case of a conventional pipe joint of this type, the pipe, the joint body, and the cap nut are almost at the same angle, and 45 degrees on one side.
It was common to form a taper surface with a 90 degree taper angle.

[0003]

In the above prior art, the gasket is simply mounted on the outer surface of the taper of the joint body so that the gasket is sandwiched between the taper surfaces. The amount of gasket compression changes. Therefore, if the cap nut is insufficiently tightened, the gasket may not be sufficiently compressed and leakage may occur.If excessively tightened, the gasket may be excessively compressed and the gasket loses elasticity due to aging and leaks. May occur.

With respect to the taper angles of the pipe, the joint body, and the cap nut, a taper angle of 90 degrees, which is generally used in the past, is theoretically based on the relationship between the clamping force in the axial direction by the cap nut and the pinching force of the pipe end. It is an angle that can be tightened stably. However, the elongation rate differs depending on the material of the pipe to be connected. For example, in the case of a thin stainless steel pipe, if it is not used at an elongation rate of 25% or less, there is a problem in that crack destruction occurs at the expanded portion at the pipe end . Therefore, when expanding the taper length taking a certain distance of the sealing surface, the growth rate of the circumference is increased by the tube of the expansion end becomes larger than the value determined for the material of the tube, when Ya expansion work of the tube There has been a problem that cracking occurs from the expanded end due to the pinching force of the expanded portion after connection. For this reason, if the expansion rate of the pipe expansion is set to be equal to or less than the predetermined value, the taper length of the expansion section becomes short, so that an appropriate seal length cannot be obtained, which leads to leakage and pipe detachment. There was a problem.
The present invention solves the above-described problems, compresses the gasket in a constant compression amount, improves the sealing effect of the gasket and long-term reliability, and increases the end of the pipe even if an expanded portion is formed in the pipe. An object of the present invention is to provide a pipe joint suitable for a thin-walled stainless steel pipe, which does not cause a problem that a crack occurs in a portion.

[0005]

SUMMARY OF THE INVENTION The gist of the present invention is to form a tapered outer surface having a taper angle extending at approximately 35 degrees in full angle on an outer surface of an end portion, providing an annular groove on the tapered outer surface, and forming an annular groove on the annular groove. It consists of a joint body fitted with packing and a cap nut having a tapered inner surface corresponding to the tapered outer surface, and expands in a trumpet shape at the end of the stainless steel pipe to be connected at a taper angle corresponding to the tapered surface. A pipe joint for stainless steel pipes, wherein a portion is provided, and the expanded portion is sandwiched between a tapered outer surface of the joint body and a tapered inner surface of a cap nut.

[0006]

Since the present invention has the above construction, when the expanded portion of the pipe is clamped between the tapered surface of the joint body and the cap nut, the packing mounted on the annular groove on the outer surface of the taper is not used. The gasket is compressed by the expanding portion, but is not compressed beyond a certain compression amount because the packing is mounted in the annular groove. For this reason, the joint body and the expanded portion of the pipe can be sealed with a compression amount that is optimal for the durable sealing property of the packing.

Further, since the taper angle of the pipe, the joint body and the cap nut is set to a taper angle of about 35 degrees which is less than half of that conventionally used, the seal length of the taper surface is reduced. Can be taken long enough and the taper angle is small.
Since the circumferential length of the expanded portion of the split tube does not increase and the elongation rate of the expanded portion does not increase, there is no problem that cracks occur at the expanded end. Further, the pinching force of the expanded portion of the pipe by the joint body and the cap nut can be more than doubled by the wedge effect even if the tightening torque of the cap nut is the same as the conventional one. Therefore, in addition to the sealing by the packing on the outer surface of the taper, the sealing between the metal surfaces by the press contact between the outer surface of the taper and the expanded portion of the pipe is reliably performed. Note that the taper angle is 3
At 0 degrees or less, there is a problem with the pull-out force of the pipe. At 40 degrees or more, the circumference of the expanded portion of the thin stainless steel pipe is increased as described above.
A problem arises because the elongation becomes too large as the length increases .

[0008]

1 and 2 show an embodiment of the present invention. In the figure, reference numeral 10 denotes a joint body, which has a taper outer surface 11 having a taper angle of 35 degrees at an end portion of the joint body 10, and an annular groove 12 provided in the taper outer surface 11. O in groove 12
The ring packing 13 is attached. A male screw 14 for screwing with a cap nut is provided at the back of the taper outer surface 11, and a fluid passage 15 is provided at the inner surface. The cap nut 20 has a female screw 21 screwed into the external thread 14 of the joint body on the inner surface and a taper inner surface 22 having a taper angle of 35 degrees behind the female screw 21. In this embodiment, a thin stainless steel pipe is used as the connecting pipe 30. This may be another steel pipe or copper pipe as long as the end of the pipe can be plastically deformed.

At the time of connection, after inserting the cap nut 20 into the pipe 30, the end of the pipe is expanded at a taper angle of 35 degrees in a trumpet shape using a pipe expander to form an expanded portion 31. After forming the enlarged portion 31 in the pipe, the cap nut 20 is screwed into the joint body 10 connected to the instrument or the like, and the cap nut 20 is fastened. As a result, the expanded portion 31 of the pipe is connected to the tapered surface 1 of the joint body and the cap nut.
It is pinched by 1 and 22. At the same time, the packing 13 mounted in the annular groove 12 is also compressed by the expanded portion 31, and the metal seal by the press contact between the taper outer surface 11 of the joint body and the expanded portion 31 of the pipe and the packing by the compression of the packing 13 are formed. Work and secure sealing properties are obtained.

[0010]

[Effect of the Invention] As described above, the present invention is based on the tape of the joint body.
The angle of the pipe has been set to approximately 35 degrees,
The length of the taper seal surface can be taken long enough,
In addition, the diameter of the expanded end is about half that of the conventional
The circumferential length of the expanded end of
There is no problem such as cracking at the end of the pipe because it is held down.
And the work of expanding the pipe can be easily performed. Further joints
A bag with the same clamping force as the conventional one at the pipe expansion section by the main body and the bag nut
Even if the nut is tightened with the tightening force, the wedge effect
More than twice the clamping force, pull-out performance of pipes and sealing
Excellent in performance, due to the metal surface of the joint body and pipe
Good sealing performance and good fire resistance. Because of this connection
When expanding pipes and tightening cap nuts during installation,
It is easier than ever and has excellent workability. Book
The invented stainless steel pipe fittings are for thin stainless steel pipes
Large effect in terms of sealability and workability as a pipe joint
To demonstrate.

[0011]

[Effect of the Invention] As described above, the present invention exerts great effects in terms of sealability and workability as a thin-walled stainless steel pipe fitting.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a state before connection according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing a state after connection according to the embodiment of the present invention.

FIG. 3 is a partial sectional view showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Joint main body 11 Tape outer surface 12 Annular groove 13 Packing 14 Male screw 20 Cap nut 21 Female screw 22 Taper inner surface 30 Connection pipe 31 Expanded part

Claims (1)

(57) [Scope of request for utility model registration] 1. A joint comprising: a tapered outer surface having a taper angle extending to approximately 35 degrees in full angle on an end outer surface; an annular groove provided on the tapered outer surface; and a packing mounted on the annular groove. A main body, and a cap nut formed with a tapered inner surface corresponding to the tapered outer surface, and provided at the end of the stainless steel tube to be connected an expanding portion that expands in a trumpet shape at a taper angle corresponding to the tapered surface; Expanding part is tapered outer surface of the joint body and tapered inner surface of cap nut
And a pipe joint for stainless steel pipes.