JPH0237015Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a connection mechanism for a thin-walled stainless steel pipe and a joint that can easily and reliably connect the thin-walled stainless steel pipe and the joint on-site.

[Conventional technology]

As a conventional technique of this type, there is a connection mechanism disclosed in Japanese Utility Model Application Publication No. 54-83612, which was previously proposed by the present applicant. As shown in FIG. 6, this connection mechanism is constructed by screwing together a nut 3, which cannot be removed from the thin-walled stainless steel tube 1 by a ring 101 fixed to the end of the thin-walled stainless steel tube 1, with a coupling 2. This is a mechanism that connects the steel pipe 1 and the joint 2. The thin stainless steel pipe 1 has a thin wall thickness that can be expanded with an expander, and has several serrated grooves 10 with a triangular cross section on the inner peripheral surface as a ring 101.
A closed annular ring 101 carved with 2 is fitted over the end of the thin-walled stainless steel tube 1, and the diameter of the end of the thin-walled stainless steel tube 1 is mechanically expanded using an expander, thereby forming a thin-walled stainless steel tube. The outer circumferential surface of the end of the thin-walled stainless steel tube 1 is fitted into the serrated groove 102 without any gaps so as not to create unevenness on the inner circumferential surface of the thin-walled stainless steel tube 1.
The ring 101 is fixed to the end of the ring 101.

[Problem that the invention attempts to solve]

However, according to the prior art, a roll-type expander must be used, and the diameter of the end of the thin-walled stainless steel tube 1 is expanded mechanically. 1 without any gaps, but work hardening occurs due to the rolling effect of the rollers. In addition, the residual force is large because the roller is subjected to repeated strain at the contact point where it passes. For this reason, there is a problem that although the tensile strength is high due to work hardening, the corrosion resistance is decreased.

Furthermore, since the ring 101 is fitted into the outer peripheral surface of the end of the thin-walled stainless steel pipe 1 without any gaps,
The ring 101 is required as an essential component. For this reason, there have been problems such as an increase in the number of parts, an increase in the price of the connection mechanism itself, and a complicated manufacturing process.

Furthermore, when the joint 2 and the nut 3 are screwed together, if the tip of the joint 2 is tightened sufficiently until it comes into contact with the ring 101, a large frictional force will be generated in the threaded part of the threaded part, and this will cause friction between the female threaded part and the male threaded part. Although a strong tightening force can be obtained by increasing the resistance, since the nut is connected with a ring in between, if a twisting torque higher than the loosening torque of the nut is applied to the pipe, the threaded part will loosen. It had a point.

[Means to solve problems]

As a result of continuing research and development to solve the above-mentioned problems, the inventor came up with a means to solve the above-mentioned problems. That is, the means includes: a thin-walled stainless steel pipe with a convex portion formed on the outer periphery of the end; a joint having an inner diameter into which the thin-walled stainless steel pipe is inserted; and a male thread formed on the outer periphery of the end; a nut having a fitting portion that externally fits into the thin-walled stainless steel pipe facing the boundary and having a female threaded portion that screws into the male thread of the joint; and a packing provided between the joint and the thin-walled stainless steel pipe;
In a connection mechanism between a thin-walled stainless steel pipe and a joint, the convex part of the thin-walled stainless steel pipe is expanded in diameter with a uniform force by expanding rubber inserted inside the convex part in the outer circumferential direction, thereby forming two inclined surfaces. A first notch is formed on the inner periphery of the end portion of the joint, the first notch consisting of a tapered portion that closely contacts the chevron-shaped projection and a gasket fitting portion, and the nut has a fitting portion thereof. A second notch is formed in the inner end of the nut to be in close contact with one of the inclined surfaces of the chevron-shaped protrusion, and when the female thread of the nut and the male thread of the joint are screwed together and fixed, the end surfaces of the joint come into contact with each other.
A joint contact surface is formed by the inner diameter difference between the fitting part and the female threaded part, and the packing is attached to the thin-walled stainless steel pipe when the male thread is screwed and fixed to the female threaded part of the nut and the joint. The other inclined surface of the formed chevron-shaped protrusion is formed so as to be in close contact with the joint contacting surface of the nut and the seal fitting part of the joint, respectively.

[Effect]

According to the above means, by forming a convex portion on the outer periphery of the end of the thin-walled stainless steel pipe, the fitting portion of the nut fitted onto the thin-walled stainless steel pipe does not come out. Then, the diameter of this convex portion expands in the outer circumferential direction with a uniform force due to the expansion of the rubber inserted inside the thin-walled stainless steel pipe, forming a chevron-shaped protrusion with two inclined surfaces. When the male thread of the nut is screwed into the female thread of the nut, the second notch formed in the fitting part of the nut comes into contact with one inclined surface, and the taper formed on the inner periphery of the end of the joint is brought into contact with the other inclined surface. furthermore, the end face of the joint abuts the joint contact surface formed on the nut, and furthermore, the gasket fitted into the gasket fitting portion formed on the inner periphery of the end of the joint contacts the other inclined surface and The thin-walled stainless steel pipe and the fitting are connected by abutting the joint contact surfaces, respectively.

In this case, all you have to do is fit the packing into the fitting part of the fitting, then screw together the male thread of the fitting and the female thread of the nut, and tighten until the end surface of the fitting contacts the joint contact surface of the nut and stops rotating. good. This creates a large frictional resistance at the threaded portion of the male thread and the female thread. At this time,
Since the frictional resistance acting on the threaded portion of the screw is greater than the frictional resistance between the thin-walled stainless steel pipe, the joint, and the nut, the nut will not loosen even if the thin-walled stainless steel pipe is twisted.

In addition, the first notch and the second notch of the joint and the nut contact the two inclined surfaces of the chevron-shaped protrusion, and are urged in opposite directions by the elasticity of the thin-walled stainless steel pipe. . Furthermore, the elasticity of the packing also adds to this biasing force. As a result, due to the action of force in the direction of separating the joint and nut from each other, a large frictional resistance is generated in the threaded portion of each male thread and female thread, making it difficult for the threaded joint to loosen. The axis of the steel pipe is held in a straight line. In addition, the tapered part of the first notch of the joint restricts the way the end of the thin-walled stainless steel pipe is inserted into the fitting part, so even when the joint and nut are tightened, the seal will not be pushed more than necessary. Never be crushed. Furthermore, the packing is equally safe even if bending, vibration, twisting, etc. occur in thin-walled stainless steel pipes. Therefore,
It is possible to extend the life of the gasket, and in addition, it is possible to prevent the threaded portion from loosening.

〔Example〕

Hereinafter, embodiments of this invention will be described based on the drawings.

The connection mechanism between the thin-walled stainless steel pipe and the joint of this invention consists of a thin-walled stainless steel pipe 1, a joint 2, a nut 3, and a packing 4, as shown in FIGS.
It consists of

The thin-walled stainless steel pipe 1 has two inclined surfaces 5 in cross section formed by expanding the pipe diameter on the outer periphery of the end thereof.
It has a convex chevron-shaped protrusion 5 having a and 5b. The joint 2 has a tapered portion 6 on the inner circumferential surface of its end.
A and a gasket fitting part 6b form a first notch 6, and a male thread 7 is formed on the outer peripheral surface of the end. The nut 3 has a fitting portion 8 that fits externally into the thin-walled stainless steel pipe 1, and is formed to have a larger inner diameter than the fitting portion 8, and has a threaded groove on the inner peripheral surface into which the male thread 7 of the joint 2 is screwed. It consists of a carved female threaded part 9, a joint contact surface 10 formed by the difference in inner diameter between the fitting part 8 and the female thread part 9, and a second notch 11 formed at the inner end of the joint contact surface 10. .
Further, the gasket 4 is used by being fitted into the gasket fitting portion 6b of the joint 2, and when the connection between the thin stainless steel pipe 1 and the joint 2 is completed, the gasket 4 is used by fitting into the gasket fitting portion 6b of the joint 2.
a, packing fitting part 6b of joint 2, nut 3
The seal is made of an elastic material such as rubber and has a rectangular cross section and has an adhesive surface that can adhere to the joint surface 10 of the joint.

The thin-walled stainless steel pipe 1, joint 2, nut 3, and packing 4 configured as described above constitute a connection mechanism as follows.

First, one or two nuts 3 are fitted onto the thin-walled stainless steel pipe 1, and then the tube diameter is expanded at one or both ends of the steel pipe 1 to form a mountain-shaped protrusion 5. At this time, the inclined surface 5b of the chevron-shaped protrusion 5
It is most desirable to make the inclination angle of the nut 3 equal to the inclination angle of the second notch 11 of the nut 3, but for this purpose, a tube expanding device as shown in FIGS. 4 and 5 is used. This tube expansion device includes a diameter expansion head 12 fixed to a base (not shown), and a diameter expansion head 12 fixed to a base (not shown).
A shaft 15 movably inserted into the interior, a rubber receiver 16 fitted onto the shaft 15, and an expanding rubber tube 17.
The main components include a rubber presser 18 and a locking portion 19 fixed to the tip of the shaft 15. The tube expansion operation is performed as follows. First, the tube expansion head 12
The male thread 13 formed on the outer periphery of the nut 3 and the female thread of the female thread part 9 of the nut 3 fitted into the thin stainless steel 1 are screwed together and fixed. At this time, thin-walled stainless steel pipe 1
From the end of the shaft 15 and the rubber receiver 16,
The tube expanding rubber 17, the rubber presser 18, and the locking part 19 are inserted at the same time. Then, when the shaft 15 is pulled in the direction of arrow A by a device not shown, the fifth
As shown in the figure, the rubber receiver 16 connects to the tube expansion head 12.
comes into contact with. After that, when the shaft 15 is pulled in the direction of arrow A, the locking part 19 pushes the rubber presser foot 18 in the direction of arrow A, so that the rubber receiver 16 and the rubber presser foot 1
The expanded tube rubber 17, which is clamped by the tube 8, has its width reduced, so that it expands in the circumferential direction by the reduced volume. On the outer periphery of this expanded tube expansion rubber 17, there is a mountain-shaped space 20 formed by the second notch 11 of the nut 3 and the notch 14 formed on the inner peripheral surface of the tip of the tube expansion head 12. As the tube expanding rubber 17 expands in the circumferential direction, the thin stainless steel tube 1 bulges into a mountain-shaped space 20 at its end, forming a mountain-shaped protrusion 5 . In this way, the chevron-shaped protrusion 5 is formed at the end of the thin-walled stainless steel pipe 1.
By forming this, the angle of inclination of the inclined surface 5b of the chevron-shaped protrusion 5 and the angle of inclination of the second notch 11 of the nut 3 are completely equal, which has the advantage that the axes coincide and the adhesion is improved. Furthermore, since the diameter is expanded by a rubber tube expansion method that applies statically uniform force to the inside of the thin-walled stainless steel tube 1, work hardening and residual stress are almost eliminated.

After completing the expansion of the thin-walled stainless steel pipe 1 as described above, the seal fitting part 6b of the joint 2
After fitting the packing 4 into the joint 2, the end of the thin stainless steel pipe 1 is inserted into the joint 2. and,
Male thread 7 and nut 3 formed on the outer periphery of the end of the joint 2
Connect the female thread of the female thread part 9 of the nut 3 to the joint surface 1 of the nut 3.
When screwed in until 0 touches the tip of joint 2,
The chevron-shaped protrusion 5 of the thin-walled stainless steel pipe 1 is connected to the tapered portion 6a of the joint 2 and the second notch 11 of the nut 3.
and is clamped and fixed by the packing 4.
Furthermore, the seal 4 is in close contact with the inclined surface 5a of the chevron-shaped protrusion 5, the seal fitting part 6b, and the joint contact surface 10, thereby preventing leakage of the fluid flowing inside the thin-walled stainless steel pipe 1.

[Effect of idea]

As is clear from the above explanation, according to the connection mechanism of the thin-walled stainless steel pipe and the joint of this invention,
It has various effects as follows.

First, when the nut and fitting are tightened strongly,
The tip of the joint stops when it hits the joint contact surface of the nut, so it does not advance any further. Therefore, neither the chevron-shaped protrusion nor the packing that is pressed by the joint will be broken or damaged, so construction can be carried out with peace of mind, and work efficiency is improved.
In addition, large frictional resistance occurs at the threaded part of the screw, and this is much greater than the frictional resistance between the thin-walled stainless steel pipe, the joint, and the nut, so even if the thin-walled stainless steel pipe is twisted, the nut will not loosen.

In addition, since the diameter is expanded by a rubber tube expansion method that statically and uniformly applies force inside the thin-walled stainless steel tube, almost no work hardening or residual stress occurs, resulting in greatly improved corrosion resistance.

Furthermore, due to the elasticity of the material of the thin-walled stainless steel pipe, when the two inclined surfaces of the chevron-shaped protrusion are clamped by the second notch of the nut and the tapered part of the joint, biasing forces in opposite directions are generated. In order to receive
The threaded part between the nut and the joint is less likely to loosen, ensuring safety.

Even if the thin-walled stainless steel pipe undergoes various changes due to expansion and contraction due to temperature changes, bending, vibration, twisting, etc., the seal is housed in the seal fitting portion, so the pressure can be avoided and the tube will not deform. As a result, the life of the gasket can be extended.

Furthermore, the packing is completely attached to the connection parts of thin-walled stainless steel pipes, fittings, and nuts, so
No fluid leaks.

In addition, since the nut and the joint are locked to the two inclined surfaces of the chevron-shaped protrusion, the strength with which the thin-walled stainless steel pipe is pulled out from the joint can be greatly improved.

In addition, since the material is thin-walled stainless steel pipe, rust does not occur, improving the durability of the entire connection mechanism.

This invention can simultaneously satisfy all of the above effects.

[Other means to solve the problem]

Of the two problems that this invention aims to solve, the means to solve the former problem are as follows:
For example, there are techniques disclosed in Japanese Utility Model Application Publication No. 47-25207, Japanese Utility Model Application Publication No. 51-15216, and Japanese Utility Model Application Publication No. 56-149186, which were proposed even earlier than the above-mentioned prior art. That is, in these techniques, an annular protrusion is provided on the outer peripheral surface of the end of the tube, and this annular protrusion is used in place of the ring of the prior art. However, none of these techniques is a means to solve the latter problem. Because, Utility Model Application No. 47-25207 and Utility Model Application No. 56-
In the technology disclosed in Japanese Patent No. 149186, when the joint and the nut are screwed together, the tip of the joint or the nut contacts only the annular protrusion of the pipe provided instead of the ring.
Furthermore, since there is a sealing in between, the stress relaxation of the annular protrusion and the sealing weakens the frictional resistance between the male thread and the female thread, and if the tightening force becomes large, it may bite into the annular protrusion and damage the pipe. At the same time, the repulsive force due to the annular protrusion weakens, and the frictional resistance between the female threaded portion and the male threaded portion also becomes weaker, so this does not solve the problem that the threaded portion easily loosens. In addition, if the tube is tightened too much, the tube may lose its restoring force and no repulsive force will be generated.

In addition, the technology disclosed in Utility Model Application Publication No. 51-15216 includes
There is one in which the tip of the joint contacts the nut and a seal ring is provided between the tip of the joint and the annular protrusion. With this technology, it is possible to tighten until the tip of the fitting contacts the nut, but the annular protrusion is not held between the fitting and the nut, and the elongation of the pipe due to heat causes the seal to repeatedly compress and expand. If a positive force (force in the direction of the joint) acts in the longitudinal direction of one pipe and exceeds this limit, the seal ring will be destroyed and the seal ring will no longer fulfill its role; If a negative force is applied in the longitudinal direction of one of the tubes, this repulsion force disappears and the sealing performance cannot be maintained, which is a disadvantage that it cannot be put to practical use.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing an embodiment of this invention, Fig. 2 is a - cross-sectional view of Fig. 1, Fig. 3 is an enlarged longitudinal cross-sectional view of Western-style rubber, and Fig. 4 is an expanded rubber tube showing a method of forming protrusions. FIG. 5 is an explanatory view from a vertical cross section during normal operation, FIG. 5 is an explanatory view from a vertical cross section during compression of expanded tube rubber, and FIG. 6 is an explanatory view of the prior art. 1... Thin-walled stainless steel pipe, 2... Fitting, 3...
Nut, 4... Packing, 5... Chevron-shaped protrusion (convex part), 5a, 5b... Inclined surface, 6... First notch,
6a...Tapered part, 6b...Puttle fitting part, 7...Male thread, 8...Fitting part, 9...Female thread, 10...Joint contact surface, 11...Second notch part.

Claims (1)

[Claims for Utility Model Registration] A thin-walled stainless steel pipe with a convex portion formed on the outer periphery of the end, a joint having an inner diameter into which the thin-walled stainless steel pipe is inserted, and a male thread formed on the outer periphery of the end;
a nut having a fitting part facing the joint and the convex part and externally fitting onto the thin-walled stainless steel pipe, and having a female thread part screwed into the male thread of the joint; and between the joint and the thin-walled stainless steel pipe. In a connection mechanism between a thin-walled stainless steel pipe and a joint, the convex part of the thin-walled stainless steel pipe is expanded in diameter with uniform force by expanding the rubber inserted inside the convex part in the outer circumferential direction. forming a chevron-shaped protrusion having two inclined surfaces; forming a first notch on the inner periphery of the end of the joint, the first notch consisting of a tapered part that tightly contacts the chevron-shaped protrusion and a gasket-fitting part; , a second notch is formed at the inner end of the fitting portion to tightly contact one of the inclined surfaces of the chevron-shaped protrusion, and when the female thread of the nut and the male thread of the joint are screwed together and fixed, the end face of the joint is formed. forming a joint contact surface formed by the difference in inner diameter between the fitting part and the female threaded part, which the fitting part and the female thread part come into contact with; The other sloped surface of the chevron-shaped protrusion formed on the thin-walled stainless steel pipe,
A connection mechanism for a thin-walled stainless steel pipe and a joint, characterized in that the nut is formed so as to be in close contact with the joint surface of the nut and the fitting part of the joint.