JP2002188766A - Pipe connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connection structure allowing the assured connection of the end parts of pipes to each other without using a liner and a C-ring. SOLUTION: In this connection method for connecting the end parts of two pipes P1 and P2 to each other by using a heat contracting cylindrical body 1 of shape memory alloy, a flare portion 11 of a generally same diameter is formed at the end part of each pipe, the flare portions opposed to each other are butted projectedly against each other, the heat contracting cylindrical body of shape memory alloy is fitted on the projectedly butted part, and the heat contracting cylindrical body is contracted by heating. Since the flare portions act as obstacles at the time of heating of the heat contracting cylindrical body, both end parts of the heat contracting cylindrical body are contracted on the outside of the flare portions by heating to firmly tighten the flare portions from both sides. As a result, the pipe can be completely prevented from being disconnected, and an increase in sealability can be expected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fastening structure for fastening two tube ends using a heat-shrinkable cylinder made of a shape memory alloy.

[0002]

2. Description of the Related Art Conventionally, when a heat-shrinkable cylindrical body made of a shape memory alloy is used to fasten two tube ends to each other, the heat-shrinkable cylindrical body made of a shape memory alloy is heated to a temperature at the end of shape recovery. When heated, the heat-shrinkable cylinder is heat-treated so as to shrink in a direction to reduce its diameter, and the heat-shrinkable cylinder is shaped under the condition that the ends of the two tubes are inserted from both ends of the heat-shrinkable cylinder. By heating to the recovery end temperature, the ends of the two tubes are fastened with the shape recovery force obtained from the shrinkage.

Therefore, theoretically, two pipes can be easily connected to each other simply by utilizing the shape recovery force of a heat-shrinkable cylinder made of a shape memory alloy. The use of the body alone causes problems in terms of sealing performance and detachment at the ends of the two pipes, so that it was necessary to take countermeasures.

[0004] With respect to the sealing property, Japanese Patent Laid-Open No.
As disclosed in JP-A-133487, a liner is interposed between a heat-shrinkable cylinder and a pipe, and in this state, the two pipes to which the liner is to be fastened are formed with a shape recovery force obtained by heating the heat-shrinkable cylinder. By strongly pressing against the outer peripheral surface of the end,
The device is designed to ensure sealing.

[0005] Further, regarding the detachment, see Japanese Patent Application Laid-Open No. 11-3 / 1999.
As shown in Japanese Patent No. 24569, annular concave grooves are formed on the inner peripheral surface of the heat-shrinkable cylindrical body and the outer peripheral surface of the end of each tube, and a C-ring is mounted on the concave groove side of the heat-shrinkable cylindrical body. In this state, insert the end of each tube from both ends of the heat-shrinkable cylinder, drop the C-ring into the groove on the tube side, and then contract the heat-shrinkable cylinder to obtain the heat-shrinkable cylinder of the tube. The device is designed to prevent the body from coming off.

[0006]

Therefore, if the above-mentioned liner or C-ring is used under a heat-shrinkable cylindrical body made of a shape memory alloy, it is possible to secure the sealing property and prevent the pipe from coming off. Although it is possible to do so, the number of parts increases, which is economically unfavorable, but also tends to make the fastening structure itself complicated.

[0007]

SUMMARY OF THE INVENTION The present invention has been developed in order to effectively solve the problems of the conventional fastening structure, and the invention according to claim 1 is a heat-shrinkable cylinder made of a shape memory alloy. In a fastening structure in which ends of two tubes are fastened to each other using a body, flared portions having substantially the same diameter are formed at the ends of each tube, and the flared portions facing each other are butt-joined to each other. The heat-shrinkable cylindrical body made of the shape memory alloy was fitted on the part, and the heat-shrinkable cylindrical body was shrunk by heating.

According to a second aspect of the present invention, in a fastening structure in which ends of two tubes are fastened to each other using a heat-shrinkable cylindrical body made of a shape memory alloy, a bulge portion is formed at an end of one of the tubes. Then, at the end of the other tube, a flare portion is formed along the tapered shape on the tube end side of the bulge portion at the same diameter as the bulge portion at the end of the other bulge portion, and the facing bulge portion and the flared portion are bonded to each other, A configuration was adopted in which the heat-shrinkable cylindrical body made of the shape memory alloy was externally fitted onto the male and female joints, and the heat-shrinkable cylindrical body was shrunk by heating.

Therefore, in the first aspect of the present invention,
Each flared part to be butt-jointed acts as an obstacle during heating of the heat-shrinkable cylindrical body. As a result, both ends of the heat-shrinkable cylindrical body made of shape memory alloy shrink outside of each flared part due to heating, and each flared part is heated. Since the tapered shape is firmly tightened from both sides, it is possible to prevent the tube from coming off and improve sealing performance without using a conventional liner or C-ring.

According to the second aspect of the present invention, similarly, the bulge portion and the flare portion to be bonded to each other act as obstacles when the heat-shrinkable cylindrical body is heated. Both ends of the body shrink outside the tapered shape of the back side of the bulge part and the tapered shape of the flare part by heating, and the bulge part and the flare part are firmly tightened from both sides, so the conventional liner and C ring Even without using, it is possible to completely prevent the detachment of the pipe, and particularly, to increase the contact area by surface contact by pressing the bulge portion and the flare portion in the direction of biting each other by the above-mentioned axial tightening. Therefore, improvement in the sealing performance can be further expected.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the present invention in detail based on a preferred embodiment illustrating the present invention, the background of the present invention will be described. When heated to the shape recovery end temperature, it shrinks with the same shape. However, as shown in FIG. 1A, when heated with a disk-shaped obstacle 2 interposed in the center of the heat-shrinkable cylindrical body 1. As shown in FIG. 1B, it has been found that the central portion of the heat-shrinkable cylindrical body 1 in which the obstacle 2 is interposed hardly shrinks, and only both end portions thereof are curved to a set diameter and shrink.

Therefore, each embodiment of the present invention has been developed focusing on the properties of such a shape memory alloy, and the fastening structure according to the first embodiment is shown in FIG. As shown, flared portions 11 each having a trumpet shape and substantially the same diameter are individually formed at the ends of the two pipes P1 and P2, and the opposing flared portions 11 are butt-joined to each other to form a shape on the butt-joint. A state in which the heat-shrinkable cylindrical body 1 made of a memory alloy is externally fitted is obtained, and the heat-shrinkable cylindrical body 1 is heated to the shape recovery end temperature.

Therefore, in the first embodiment,
Since each of the flared joints 11 serves as the above-described obstacle 2, the heated heat-shrinkable cylinder 1 does not shrink at a position corresponding to the flare 11, but is shown in FIG. 2B. As described above, since both ends are curved and contracted, and the tapered shape of each flare portion 11 is firmly tightened from both directions, the pipes P1 and P2 can be pulled out without using a conventional liner or C-ring. The detachment can be completely prevented, and the improvement of the sealing property can be expected.

Next, the fastening structure according to the second embodiment will be described. In the second embodiment, as shown in FIG. 3A, the end of one pipe P1 has a bulging shape. A bulge portion 12 is formed, and the bulge portion 12 is attached to the end of the other tube P2.
And a flared portion 11 having a maximum diameter substantially the same as the tapered shape on the tube end side of the bulge portion 12 is formed, and the opposing bulge portion 12 and the flared portion 11 are bonded together by male and female. The heat-shrinkable cylindrical body 1 is heated to the shape recovery end temperature in a state where the heat-shrinkable cylindrical body 1 made of an alloy is fitted to the outside.

Therefore, even in the second embodiment,
Since the bulge portion 12 and the flare portion 11 which are joined together by the male and female act as the obstacle 2, the heated heat-shrinkable cylinder 1 does not shrink at the central portion corresponding to the male and female joints. As shown in FIG. 2, both ends are curved and contracted, and the tapered shape on the back side of the bulge portion 12 and the tapered shape of the flare portion 11 are firmly tightened from both sides. Without using the C-ring, the tubes P1 and P2 can be completely prevented from coming off, and the bulge portion 12 and the flared portion 11 are pressed in a direction in which the bulge portion 12 and the flared portion 11 bite into each other by the above-described axial tightening, so that surface contact is achieved. Since the contact area is increased, it is possible to expect further improvement in the sealing performance.

In the second embodiment, as shown in FIG. 4, a parallel portion 12a having the same diameter as the inside diameter of the other tube P2 is provided at the tip of the bulge portion 12 on the side of one tube P1. If this is done, it goes without saying that the sealing performance due to surface contact is further improved, but the bending strength of the male and female joint is significantly improved.

In the above embodiments, the cross-sectional shape of the heat-shrinkable cylindrical body 1 is simply rectangular, but as shown in FIG. An arcuate shape 3 is provided, an angled mountain shape 4 is provided on the inner peripheral side of the cross section as shown in FIG. 5B, or both ends on the inner peripheral side of the cross section as shown in FIG. 5C. If the convex wall 5 is formed so as to protrude toward the center, the above-mentioned properties of the shape memory alloy can be more positively utilized. Further, the shape memory alloy referred to here indicates an irreversible transformation iron-based shape memory alloy or the like.

[0018]

As described above, according to the present invention, according to the first aspect of the present invention, each flared portion to be butt-joined acts as an obstacle at the time of heating the heat-shrinkable cylindrical body.
Both ends of the heat-shrinkable cylindrical body made of shape memory alloy shrink outside of each flared part due to heating, and the tapered shape of each flared part is firmly tightened from both sides, so there is no need to use a liner or C ring as in the past. In both cases, the detachment of the tube can be prevented, and the improvement of the sealing property can be expected.

According to the second aspect of the present invention, similarly, the bulge portion and the flare portion which are bonded to each other act as obstacles when the heat-shrinkable cylinder is heated, so that both ends of the heat-shrinkable cylinder made of shape memory alloy are heated. As it contracts outside the tapered shape of the back side of the bulge part and the tapered shape of the flare part, it tightly tightens the bulge part and the flare part from both sides,
Without using a conventional liner or C-ring, the tube can be completely prevented from coming off, and in particular, by pressing in the above-described axial direction, the bulge portion and the flare portion are pressed in a direction to bite each other, Since the contact area due to the surface contact is increased, the improvement of the sealing property can be further expected.

[Brief description of the drawings]

FIGS. 1A and 1B are explanatory diagrams illustrating properties of a shape memory alloy to which the present invention focuses.

FIGS. 2A and 2B are cross-sectional views showing a fastening structure according to the first embodiment of the present invention.

FIGS. 3A and 3B are cross-sectional views showing a fastening structure according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a modification of the second embodiment.

FIGS. 5A, 5B, and 5C are cross-sectional views showing other examples of the cross-sectional shape of the heat-shrinkable cylindrical body.

[Description of Signs] 1 Heat-shrinkable cylindrical body made of shape memory alloy 2 Obstacle 3 Concave arc shape 4 Angled mountain shape 5 Convex wall 11 Flare portion 12 Bulge portion 12a Parallel portion P1 tube P2 tube

Claims (2)

[Claims] 1. A fastening structure for fastening ends of two tubes using a heat-shrinkable cylindrical body made of a shape memory alloy,
A flare portion having substantially the same diameter is formed at the end of each tube, and the opposing flare portions are butt-joined to each other, and the heat-shrinkable cylindrical body made of the shape memory alloy is fitted on the butt joint. Wherein the heat-shrinkable cylindrical body is shrunk by heating. 2. A fastening structure for fastening the ends of two tubes using a heat-shrinkable cylindrical body made of a shape memory alloy,
A bulge portion is formed at one end of the tube, and a flare portion is formed at the end of the other tube along the tapered shape on the tube end side of the bulge portion having a maximum diameter substantially the same as that of the bulge portion and facing each other. The bulge portion and the flare portion are joined together by male and female, and a state is obtained in which the heat-shrinkable cylindrical body made of the shape memory alloy is externally fitted on the male and female joints, and the heat-shrinkable cylindrical body is shrunk by heating. Pipe fastening structure.