JP2000230676A - Structure of connecting thin-walled stainless steel pipe and joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To elongate a life of a packing while reducing contact between a packing and a fluid flowing therethrough while preventing deterioration of the packing, and reduce a processing cost while providing an inner peripheral surface of an end of the joint with an easily processable form. SOLUTION: A projection 7 formed with two tapered surfaces 5, 6 is formed on an end of a thin stainless steel pipe 1, while a pacing fitting part 10 is formed on an inner periphery of an end of a joint 2. A first close contact portion 16 composed of a corner is formed so as to bite into the tapered surface 5 of the projection 7. A second close contact portion 17 composed of a tapered surface in close contact with the tapered surface 6 of the projection is formed on an inner side end of a fitting portion 12 of a nut 3. In addition, a joint abutting surface 14 against which an end face of a joint 2 is abutted is formed. The packing 4 is brought into close contact respectively with the tapered surface 5 of the projection 7, the joint abutting surface 14 and the second packing fitting part 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin-walled stainless steel tube and a joint connecting mechanism which can easily and reliably connect the thin-walled stainless steel tube and a joint on site.

[0002]

2. Description of the Related Art As a conventional connection mechanism between a thin-walled stainless steel pipe and a joint, Japanese Utility Model Application Publication No.
There is a connection mechanism disclosed in Japanese Patent No. 37015. This connection mechanism, as shown in FIG.
It is composed of a joint 2, a nut 3 and a packing 4. The thin stainless steel pipe 1 is formed with a mountain-shaped projection 7 having two inclined surfaces 5 and 6 on the outer periphery of the end. The joint 2 has an inner diameter into which the thin stainless steel tube 1 is inserted, and an external thread 8 is formed on an outer peripheral surface of an end portion thereof.
A first cutout portion 11 is formed on the inner periphery of the end portion, the first cutout portion 11 including a tapered portion 9 and a packing fitting portion 10 which are in close contact with one of the inclined surfaces 5 of the chevron-shaped projection 7. The nut 3 is
A fitting portion 12 which is externally fitted to the thin-walled stainless steel pipe 1 so as to face the joint 2 and the chevron-shaped projection 7 as a boundary;
Female screw portion 13 screwed into male screw 8 of
And a joint abutment surface 14 formed by a difference in the inner diameter of the female screw portion 13, and a second notch in close contact with the other inclined surface 6 of the chevron-shaped protrusion 7 at the inner end of the fitting portion 12. A part 15 is formed. The packing 4 is provided between the joint 2 and the thin stainless steel pipe 1, and when the female screw portion 13 of the nut 3 and the male screw 8 of the joint 2 are screwed together, one of the mountain-shaped protrusions 7 is provided. Inclined surface 5, joint abutment surface 14 of nut 3 and packing fitting portion 1 of joint 2
0 are formed so as to be in close contact with each other.

[0003]

However, according to the above-mentioned conventional connection mechanism, the packing 4 is easily deteriorated because it comes into contact with the fluid flowing inside, and the period in which the sealing property can be maintained is short. There is. That is, as described above, the conventional connection mechanism includes the packing 4
Is one of the inclined surfaces 5 of the chevron-shaped projections 7 and the nut 3
Of the thin-walled stainless steel pipe 1 and the joint 2 is a structure that ensures tightness by tightly contacting each of the joint abutting surface 14 and the packing fitting portion 10 of the joint 2. It is possible to intrude into the inclined surface 5 of the protrusion 4 and the inclined surface 5 of the mountain-shaped projection 7 or the contact surface between the fitting 2 and the packing fitting portion 10 of the joint 2. Therefore, the packing 4 always comes into contact with the fluid flowing therein, which causes oxidation and deterioration of the packing 4, resulting in a problem that the deterioration is accelerated and the life is shortened.

A tapered portion 9 is provided on the inner periphery of the end of the joint 2 together with the packing fitting portion 10 so as to be in intimate contact with one inclined surface 5 of the chevron-shaped projection 7.
It is very difficult to machine the inner circumference of the pipe at a fixed angle like the tapered portion 9, and there is a problem that the machining cost is increased.

On the other hand, with the improvement of the performance of the tube expanding device for processing the angled projections 7 on the outer periphery of the end of the thin-walled stainless steel pipe 1, the cross-sectional shape of the angled projections 7 secures a high roundness. It became possible to do. Therefore, even when the cross-sectional shape of the thin-walled stainless steel pipe 1 is slightly distorted, the cross-sectional shape of the chevron-shaped projection 7 can ensure high roundness by processing with the expanding device. it can. Thereby, a certain degree of hermeticity is ensured even at the contact portion between the metals between the one inclined surface 5 of the chevron-shaped projection 7 and the tapered portion 9 formed on the inner periphery of the end of the joint 2. I can do it. Therefore, the necessity of ensuring the sealing performance as in the related art by relying only on the packing 4 is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is intended to prevent the packing from deteriorating and to prolong its life by reducing the contact between the packing and a fluid flowing therein. An object of the present invention is to reduce the processing cost by making the shape of the inner circumference of the end of the joint easy to process.

[0007]

Means for solving the above problems are as follows. That is, the connecting mechanism of the thin stainless steel pipe and the joint according to claim 1 has a thin stainless steel pipe having a convex portion formed on the outer periphery of the end, an inner diameter for inserting the thin stainless steel pipe, and a male screw on the outer peripheral surface of the end. A formed joint, a nut having a fitting portion externally fitted to the thin-walled stainless steel pipe facing the joint and the convex portion, and having a female thread portion screwed into a male screw of the joint; and the joint and the thin-walled portion. In the connecting mechanism of a thin stainless steel pipe and a joint composed of a packing provided between stainless steel pipes, a convex portion of the thin stainless steel pipe is formed into a mountain-shaped projection having two inclined surfaces, and the joint has A packing fitting portion is formed on the inner periphery of the end portion, and the packing fitting portion is formed by a step between the packing fitting portion and the inner peripheral surface of the joint, and bites into one inclined surface of the chevron projection. A first contact portion formed of a corner portion that is in close contact is formed, and a second contact portion formed of an inclined surface that is in close contact with the other inclined surface of the chevron-shaped protrusion is formed on the nut at the inner end of the fitting portion. And a joint abutting surface formed by an inner diameter difference between the fitting portion and the female screw portion with which an end surface of the joint abuts when the female screw portion of the nut and the male screw of the joint are screwed and fixed. When the female screw portion of the nut and the male screw of the joint are screwed together, the nut is formed so as to be in close contact with one inclined surface of the angled projection, the joint contact surface, and the packing fitting portion of the joint. It is characterized by the following.

According to a second aspect of the present invention, there is provided a connecting mechanism for connecting a thin stainless steel pipe and a joint according to the first aspect, wherein the joint is provided with a flange having a flange end surface adjacent to a male screw formed on an outer peripheral surface of the end portion. A disc spring having a colored convex surface facing the flange end surface side is externally fitted to the male screw.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A connecting mechanism between a thin stainless steel pipe and a joint according to an embodiment of the present invention will be described below with reference to the drawings. The connection mechanism of the thin-walled stainless steel pipe and the joint according to the first embodiment of the present invention is a partially enlarged cross-sectional view of the connection mechanism in FIG. 1, a cross-sectional view of the connection mechanism in FIGS.
As shown in FIG. 3 which is a cross-sectional view of FIG. 3, the thin stainless steel pipe 1, the joint 2, the nut 3, and the packing 4 are provided.
Note that the same parts as those of the above-described conventional technology are denoted by the same reference numerals and described.

The thin-walled stainless steel pipe 1 has two inclined surfaces 5, 6 formed on the outer periphery of the end by increasing the diameter of the pipe.
And a convex mountain-shaped projection 7 having the following shape. One of the two inclined surfaces 5 and 6 of the mountain-shaped projection 7 is
Closely contact the first contact portion 16 and the packing 4 of the joint 2;
The other inclined surface 6 is a second inclined surface of the nut 3.
It is in close contact with the contact portion 17. Therefore, it is desirable that the inclination angle of the other inclined surface 6 and the inclination angle of the second contact portion 17 be equal, and for that purpose, using the tube expanding device 18 as shown in FIGS. The projection 7 is formed. The method for forming the chevron-shaped projection 7 is not limited to this, but may be another method.

An expansion device 18 shown in FIGS. 4 and 5 includes an expansion head 19 fixed to a base (not shown) and an expansion head 1.
9, a rubber receiver 21 externally fitted to the shaft 20, expanded rubber 22 and a rubber presser 23, and a locking portion 24 fixed to the tip of the shaft 20.
Is a main component.

The pipe expanding operation is performed as follows. First, as shown in FIG. 4, a male screw 25 formed on the outer periphery of the pipe expansion head 19 and a female screw of the female screw portion 13 of the nut 3 externally fitted to the thin stainless steel pipe 1 are screwed and fixed.
At this time, the shaft 20, the rubber receiver 21, the expanded rubber 22, the rubber retainer 23, and the locking portion 24 are inserted simultaneously from the end of the thin stainless steel tube 1. Then, when the shaft 20 is pulled in the direction of arrow P by a device (not shown), the locking portion 24 presses the rubber presser 23 in the direction of arrow P as shown in FIG. The expanded rubber 22 sandwiched by the rubber retainers 23 and pressed from both sides has its axial width reduced, and expands in the circumferential direction by the reduced volume. On the outer periphery of the expanded rubber 22, the second nut 3
Since there is a mountain-shaped space formed by the contact portion 17 and the notch 26 formed in the inner peripheral surface of the distal end of the pipe expansion head 19, the thin wall is formed with the expansion of the pipe expansion rubber 22 in the circumferential direction. The stainless steel pipe 1 bulges at its end along the second close contact portion 17 of the nut 3 and the notch 26 formed at the inner peripheral surface of the distal end of the pipe expansion head 19 to form a mountain-shaped projection 7.

When the mountain-shaped projection 7 is formed in this manner, the inclination angle of the other inclined surface 6 and the second contact portion 1
Since the inclination angle of 7 is completely equal, there is an advantage that the axes are aligned and the degree of adhesion is improved. Further, since the diameter is expanded by a rubber expansion method in which a uniform force is statically applied to the thin-walled stainless steel pipe 1, the processing can be performed with almost no work hardening and residual stress.

As shown in FIGS. 1 to 3, the joint 2
Has an inner diameter into which the thin stainless steel tube 1 is inserted,
An external thread 8 is formed on the outer peripheral surface of the end portion, a packing fitting portion 10 is formed on the inner peripheral portion of the end portion, and a step between the packing fitting portion 10 and the inner peripheral surface 27 of the joint 2 is formed. A first contact portion 16 is formed as a corner portion that bites into one of the inclined surfaces 5 of the portion 7 and adheres tightly.
Here, the first contact portion 16 is a right-angled corner formed by the vertical surface of the packing fitting portion 10 and the inner peripheral surface 27, but is not limited thereto.
The corner may have another angle according to the shape of the packing fitting portion 10. As described above, by utilizing the step between the packing fitting portion 10 and the inner peripheral surface 27 of the joint 2, it is not necessary to machine an inclined surface on the inner periphery of the joint 2 as in the related art, thereby simplifying the shape. Therefore, the processing cost of the joint 2 can be reduced.

Further, as described above, with the improvement of the performance of the pipe expanding device, the cross-sectional shape of the angled projection 7 of the thin-walled stainless steel pipe 1 can secure a high roundness. Even if the first contact portion 16 is a close contact between the metals that bite into one of the inclined surfaces 5 of the chevron-shaped protrusion portion 7, high hermeticity can be ensured. This allows
The packing 4 only plays the role of ensuring the airtightness so that the fluid leached beyond the first contact portion 16 does not leak to the outside, and the packing 4 comes into contact with the fluid flowing inside. So there ’s almost nothing going on,
Oxidation and deterioration of the packing 4 can be prevented to prevent deterioration, and the life of the packing 4 can be extended. Specifically, in the conventional connection mechanism between the thin stainless steel pipe and the joint, the life of the packing 4 is 30 to
According to the present invention, what was about 50 years ago,
The life can be extended up to about three times.

The nut 3 has a fitting portion 12 that fits outside the thin stainless steel tube 1, and has an inner diameter larger than that of the fitting portion 12, and is screwed into the male screw 8 of the joint 2 on the inner peripheral surface. Female thread portion 13 having a thread groove formed therein;
A joint abutting surface 14 formed by a difference between the inner diameters of the inner and female threads 13 and an inclined surface formed on the inner end of the fitting portion 12 and in close contact with the other inclined surface 6 of the chevron projection 7. And two close contact portions 17.

The packing 4 is used by being fitted into a packing fitting portion 10 of the joint 2 when the female screw portion 13 of the nut 3 and the male screw 8 of the joint 2 are screwed and fixed. When the connection between the thin stainless steel pipe 1 and the joint 2 is completed, the one inclined surface 5 of the angled projection 7 of the thin stainless steel pipe 1, the joint contact surface 14 of the nut 3, and the packing fitting part 10 of the joint 2 Are formed in a ring shape having contact surfaces that can be brought into close contact with each other. The material is made of elastic rubber or the like.

The thin stainless steel pipe 1, the joint 2, the nut 3, and the packing 4 having the above-described structure constitute a connection mechanism as follows. First, one or two nuts 3 are externally fitted to the thin-walled stainless steel pipe 1, and then, at one end or both ends of the thin-walled stainless steel pipe 1, the pipe diameter is increased as described above to form a convex mountain-shaped projection. The part 7 is formed.
Further, the packing 4 is fitted into the packing fitting portion 10 of the joint 2. Then, the thin stainless steel pipe 1
Is inserted into the joint 2 and the male screw 8 formed on the outer peripheral surface of the end of the joint 2 and the female screw 1 of the nut 3 are inserted.
3 is screwed together with the female screw of
4 is screwed until it comes into contact with the end face of the joint 2. Thereby, the chevron projection 7 of the thin stainless steel pipe 1 is
The first contact portion 16 of the joint 2, the packing 4, and the second contact portion 17 of the nut 3 are sandwiched and fixed from both sides.

At this time, the first contact portion 16 bites into one of the inclined surfaces 5 of the chevron-shaped projection portion 7 to secure the hermeticity by the close contact between the metals, thereby securing the thin stainless steel pipe 1 and the joint 2. The gasket 4 prevents leakage of the fluid flowing inside, and the packing 4 is in close contact with the one inclined surface 5 of the chevron-shaped projection 7, the joint contact surface 14 of the nut 3, and the packing fitting portion 10 of the joint 2. In addition, it plays a role in ensuring the airtightness so that the fluid leached beyond the first contact portion 16 does not leak to the outside. As described above, the packing 4 has a structure in which only the sealing property is ensured in an auxiliary manner, so that the packing 4 hardly comes into contact with the fluid flowing therein, so that the packing 4 is not oxidized or deteriorated. Thus, the deterioration can be prevented, and the life of the packing 4 can be prolonged. In addition, since the nut 3 is provided with the joint contact surface 14, the nut 3
Can be tightened only to a position where the joint contact surface 14 contacts the end face of the joint 2, so that the packing 4 is not pressed more than necessary. Life can be extended.

Further, the first contact portion 16 of the joint 2 and the second contact portion 17 of the nut 3 abut on the two inclined surfaces 5 and 6 of the chevron-shaped projection 7 respectively, and the opposite directions are opposite to each other. It is urged by the elastic force of the thin stainless steel tube 1. Further, the elastic force of the packing 4 is added to this.
As a result, a large frictional resistance is generated in the threaded portion between the male screw 8 of the joint 2 and the female screw portion 13 of the nut 3 so that the screw is not easily loosened, and the axis of the thin stainless steel pipe 1 and the joint 2 are held in a straight line. Is done.

As shown in FIGS. 6 and 7, a thin stainless steel pipe, a joint 2, a nut 3, a packing 4, and a disc spring 28 are shown in FIGS. Consists of Among them, the thin stainless steel pipe 1, the nut 3, and the packing 4 are the same as the connecting mechanism of the thin stainless steel pipe and the joint according to the first embodiment. In the present embodiment, the joint 2 is provided with a flange 30 having a flange end surface 29 adjacent to the male screw 8 formed on the outer peripheral surface of the end. The flange end surface 29 is formed so as to face the nut end surface 31 when the nut 3 is screwed into the male screw 8.
Further, the disc spring 28 is externally fitted to the male screw 8 of the joint 2 so as to be located between the nut end face 31 and the flange end face 29 when the nut 3 is screwed into the joint 2. The convex surface 32 is colored.

The structure of the connecting mechanism between the thin stainless steel pipe and the joint according to the second embodiment of the present invention having the above-described structure is basically the same as that of the first embodiment.
When screwing the nut 3 into the male screw 8 of the joint 2,
When the nut 3 is screwed in, as shown in FIG.
The disc spring 28 externally fitted so as to be located between the nut end face 31 and the flange end face 29 is connected to the nut end face 3.
1 and the flange end surface 29 are pressed from both sides. Then, when the joint contact surface 14 of the nut 3 is screwed in until it comes into contact with the end surface of the joint 2, the disc spring 28 comes into close contact with the nut end face 31 and the flange end face 29, and the disc spring 28 The colored portion applied to the convex surface 32 is completely hidden and cannot be seen. That is, when the nut 3 is screwed in, the position where the colored portion applied to the convex surface 32 of the disc spring 28 disappears is the position where the proper amount of tightening is performed. Can easily be visually confirmed, so that excessive or insufficient tightening and forgetting to tighten can be prevented. Further, since the joint 2 and the nut 3 are urged in opposite directions by the repulsive force of the disc spring 28, the threaded portion between the male screw 8 of the joint 2 and the female thread portion 13 of the nut 3 is provided. Large frictional resistance is generated, making it difficult to loosen.

[0023]

As described above, according to the first aspect of the present invention,
Has the following effects. That is, in a state where the thin-walled stainless steel pipe and the joint are connected, the first contact portion formed on the joint bites into one of the inclined surfaces of the chevron-shaped projections, and secures hermeticity by close contact between the metals. Thus, leakage of the fluid flowing through the thin stainless steel pipe is prevented. Therefore, the packing is in close contact with the one inclined surface of the chevron-shaped projection, the joint abutment surface of the nut, and the packing fitting portion of the joint, and the fluid that has leached beyond the first contact portion is outside. Only plays the role of ensuring the sealing performance so as not to leak to the packing.Since the packing hardly comes into contact with the fluid flowing inside, it is possible to prevent the packing from being oxidized or deteriorated and prevent deterioration. It is possible to extend the life of the packing.

Further, since the first contact portion is constituted by a step between the packing fitting portion and the inner peripheral surface of the joint, it is not necessary to machine an inclined surface on the inner periphery of the joint as in the conventional case. Since the shape of the inner peripheral surface of the joint can be simplified, the processing cost of the joint can be reduced.

The connecting mechanism for connecting the thin-walled stainless steel pipe and the joint according to the second aspect of the present invention provides, in addition to the effect of the first aspect, whether or not the colored portion of the disc spring externally fitted to the external thread of the joint is visible. In addition, it is possible to visually confirm the appropriate amount of tightening easily, and to prevent excessive or insufficient tightening or forgetting to tighten. Also, since the joint and the nut are urged in opposite directions by the repulsive force of the disc spring, a large frictional resistance is generated at a threaded portion between the male screw of the joint and the female thread of the nut, and the joint is loosened. It becomes difficult.

[Brief description of the drawings]

FIG. 1 is a partially enlarged cross-sectional view of a connection mechanism according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the connection mechanism according to the first embodiment of the present invention.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a sectional view showing a state before pipe expansion by a pipe expansion device for forming a mountain-shaped projection;

FIG. 5 is a sectional view showing a state after pipe expansion by a pipe expansion device for forming a mountain-shaped projection;

FIG. 6 is a partially enlarged cross-sectional view showing a state before a nut is tightened of a connection mechanism according to a second embodiment of the present invention.

FIG. 7 is a partially enlarged cross-sectional view showing a state after tightening a nut of a connection mechanism according to a second embodiment of the present invention.

FIG. 8 is a partially enlarged cross-sectional view of a connection mechanism according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thin stainless steel pipe 2 Joint 3 Nut 4 Packing 5, 6 Inclined surface of angle projection 7 Angle protrusion 8 Male screw of joint 10 Packing fitting portion 12 Nut fitting portion 13 Nut female screw portion 14 Nut joint abutment Surface 16 First contact portion 17 Second contact portion 27 Inner peripheral surface of joint 28 Disc spring 29 Flange end face 30 Flange 31 Nut end face 32 Convex face of disc spring

Claims (2)

[Claims] 1. A thin stainless steel tube having a convex portion formed on the outer periphery of an end, a joint having an inner diameter for inserting the thin stainless steel tube and having a male screw formed on the outer peripheral surface of the end, and a boundary between the joint and the convex portion. A nut having a fitting portion externally fitted to the thin-walled stainless steel pipe and having a female threaded portion screwed into a male screw of the joint; and a packing provided between the joint and the thin-walled stainless steel pipe. In the connecting mechanism between the thin-walled stainless steel pipe and the joint, the convex part of the thin-walled stainless steel pipe is formed into a mountain-shaped projection having two inclined surfaces, and the joint is formed with a packing fitting part on an inner periphery of an end thereof, A first contact portion formed by a step formed between the packing fitting portion and an inner peripheral surface of the joint, the first contact portion including a corner portion that bites into one inclined surface of the chevron-shaped projection portion and adheres tightly; A second contact portion formed of an inclined surface which is in close contact with the other inclined surface of the angled projection at an inner end of the fitting portion, and a female screw portion of the nut and a male screw of the joint are screwed and fixed. When the end face of the joint abuts, a joint abutment surface formed by the difference between the inner diameters of the fitting portion and the female screw portion is formed, and the packing is screwed into the female screw portion of the nut and the male screw of the joint. The thin stainless steel pipe and the joint connecting mechanism are formed so as to be in close contact with the one inclined surface of the chevron-shaped projection, the joint abutting surface, and the packing fitting portion of the joint. 2. A joint having a flange having a flange end surface adjacent to a male screw formed on an outer peripheral surface of an end portion of the joint, and a disc spring having a colored convex surface facing the flange end surface side is provided on the male screw. 2. The connection mechanism between a thin-walled stainless steel pipe and a joint according to claim 1, wherein the joint is externally fitted.