JPH09273673A - Coupling structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coupling structure by which a packing is not to be damaged or projected outward caused by excessive fastening of a cap nut, or the packing is not damaged or the life is not shortened after torsion load is generated between the inside and the outside of the packing by the rotation for fastening the cap nut. SOLUTION: In a coupling mechanism in which a flare part 2a of a pipe 2 is overlapped on a conical outer surface 1a of a coupling part 1, a packing 3 for covering the flare part 2a and the conical outer surface 1 is mounted, a cap nut 4 is screwed to an external thread 1b, and the packing 3 is fastened and sealed, contact parts 4a, 1c to be brought in contact with each other when the packing 3 is properly fastened are respectively provided on the cap nut 4 and the coupling part 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint structure for connecting a metal pipe such as a stainless pipe to a joint such as a stainless valve or a stainless pipe joint.

[0002]

7 and 8 show a conventional example of this type of pipe joint. The pipe joint of FIG. 7 has a conical shape formed at the tip of a joint portion 22 such as a valve or a pipe joint. Outer surface 22b
The flare portion 24a formed at the tip of the pipe 24 is overlapped with the inner surface thereof, a packing 23 covering the flare portion 24a and the conical outer surface 22b is attached, and the cap nut 21 is attached to the male screw 22a formed on the outer peripheral surface of the joint portion 22. It is a joint having a structure in which the packing 23 is screwed in to tighten and seal the packing 23.

FIG. 8 shows another conventional example. This pipe joint has the structure shown in FIG. 7, and a ring 25 is internally provided in a part of the inner periphery of the cap nut 21. The rear end is extended to between the pipe 24 and the cap nut 21, and the tightening of the cap nut 21 deforms the ring 25 so that the rear end edge of the ring 25 projects outward from the end surface of the cap nut 21. It is a pipe joint.

[0004]

However, in the above-mentioned conventional pipe joint, the packing 23 is formed at the tip of the joint portion 22 and the tip of the pipe 24 by the tightening of the cap nut 21. Flared part 24
Since it is strongly crimped to the outer surface 24b of a, the sliding action on this crimping surface is unlikely to occur, while the packing 23 in FIG. 7 also contacts the inner peripheral surface 21a and the inner side surface 21b of the cap nut 21. Further, since the packing 23 in FIG. 8 is in contact with the entire inner peripheral surface 21a of the cap nut 21, by screwing the cap nut 21 into the male screw 22a, a strong contact surface pressure is exerted also on these contact surfaces. Occurs and the sliding action becomes difficult.

Therefore, the packing 23 has a joint portion 22.
Conical outer surface 22b of flare and flare portion outer surface 24 of pipe 24
A force in the opposite direction, that is, a torsion load is applied between the surface that is crimped to a and the surface that contacts the inner peripheral surface 21a and the inner side surface 21b of the cap nut 21. Furthermore, a strong compressive force, that is, a compressive load is applied to the packing 23 by screwing the cap nut 21 into the male screw 22a of the joint portion 22. As described above, since the packing 23 is applied with the torsion load and the compression load, the packing 23 is easily damaged or broken by tightening the cap nut 21.

When the packing 23 is damaged or destroyed as described above, the packing 23 easily squeezes out at the portions (a) and (b) shown in FIGS. 7 and 8. Since the packing 23 loses elasticity and a gap is created due to breakage, there are major problems such as loss of sealing property and shortening of life.

The present invention has been developed as a result of earnest research in view of the above conventional circumstances, and an object of the present invention is to prevent the cap nut from being excessively screwed into the external thread of the joint portion. An object of the present invention is to provide a joint structure capable of exhibiting the sealing property of the packing for a long period of time and thus extending the life.

[0008]

In order to achieve the above object, the present invention provides a conical outer surface formed at the tip of a joint such as a valve or a pipe joint with an inner surface of a flare formed at the tip of a pipe. In a joint structure in which a packing that covers this flare and the conical outer surface is installed, and a cap nut is screwed into the male screw formed on the outer peripheral surface of the joint to tighten the seal, seal the cap nut and the joint. It is a joint structure provided with abutting portions that abut when properly tightened.

In this case, a metal washer is integrally formed on the packing so as to cover the outer peripheral portion facing the cap nut, and the tip of the washer is bent to form a fold. A structure in which the curved portion is embedded in the packing to increase the adhesive force between the packing and the washer is preferable. Further, the rear end of the washer extends to between the pipe and the cap nut, and the washer is deformed by tightening the cap nut so that the rear end edge of the washer projects outward from the end face of the cap nut. Preferably.

The packing may be formed by integrally coating a resin such as PTFE so as to cover the outer peripheral portion facing the cap nut, and a lubricant such as PTFE coating agent may be sprinkled on the packing. Alternatively, a backup ring that slides between itself and the cap nut may be mounted at an appropriate position.

In the joint structure of the present invention, the packing is mounted so as to cover the flare portion of the pipe and the conical outer surface of the joint portion, and is tightened by screwing the cap nut into the external thread of the joint portion. The fluid inside does not leak from the seam. Further, the cap nut can be tightened only until the cap nut and the contact portion provided on the joint come into contact with each other. At this time, the packing is in a completely tightened state, The nut will not be screwed in too much and the packing will not be damaged and will not stick out, resulting in loss of sealing performance and shortened life.

Further, the packing is made of a metal washer or PTF so as to cover most of the outer peripheral surface and the side surface facing the cap nut.
Formed by integrally coating a resin such as E, spraying an antifriction agent such as PTFE on the outer peripheral surface and side surfaces, and sliding between the outer peripheral surface and side surfaces at appropriate places with the cap nut. If you wear a backup ring that does exercise,
Due to these functions, most of the outer peripheral surface and side surfaces of the packing are not rotated by the cap nut when tightening the cap nut, so there is no galling or twisting load on the packing between the inside and the outside of the packing. The packing will not be damaged.

Further, when a metal washer is integrally covered so as to cover most of the outer peripheral surface and the side surface of the packing that face the cap nut, the bent portion is formed by bending an appropriate portion of the washer. When is embedded in the packing, the washer is extremely firmly attached to the packing.

Further, one side of the washer extends up to between the pipe and the cap nut, the washer is deformed when the cap nut is tightened, and the cap nut is screwed in until the cap nut and the abutting portion of the joint come into contact with each other. If the washer is configured so that the edge of the washer projects outward from the end surface of the cap nut by a predetermined length, the completion of tightening the cap nut can be visually confirmed and insufficient tightening can be prevented. .

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partial longitudinal sectional view showing an embodiment of a joint structure of the present invention, in which 1 is a stainless valve, a joint portion such as a stainless pipe joint, and 2 are connected. A metal pipe such as a stainless steel pipe, 3 is a ring-shaped elastic packing made of rubber, and 4 is a cap nut. The conical outer surface 1a formed at the tip of the joint part 1 is formed at the tip of the pipe 2. The inner surface 2b of the flared portion 2a is overlaid, and the packing 3 that covers the flared portion 2a and the outer conical outer surface 1a is attached, and the cap nut 4 is screwed into the male screw 1b formed on the outer peripheral surface of the joint portion 1. The packing 3 is tightened for sealing.

The cap nut 4 and the joint portion 1 are in contact with the contact portion 4
a and 1c are provided, and the cap nut 4 is attached to the male screw 1b.
When the packing 3 is screwed in and the packing 3 is completely tightened, the contact portions 4a and 1c contact each other.

Further, the packing 3 is integrally formed with a metal washer 5 so as to cover most of the outer peripheral surface 3a and the side surface 3b facing the cap nut 4. Further, an appropriate portion of this washer 5, that is, a bent portion 5a which is a portion shown by a broken line in the embodiment shown in FIG. 1, is bent as shown in a partial perspective view of the washer shown in FIG. Is embedded in the packing 3 to increase the adhesive force between the packing 3 and the washer 5.

FIG. 3 shows a state before the cap nut 4 having the joint structure shown in FIG. 1 is screwed into the joint portion 1 and tightened,
That is, FIG. 3 is a partial vertical sectional view showing a temporarily tightened state.
As shown in Fig. 3, the washer 5 of the packing 3 has a pipe 2 on one side.
And the cap nut 4 extend so as to enter between the cap nut 4 and the side face 3b of the packing 3, and the cap nut 4 has a shape that does not adhere to the cap nut 4 as shown in FIG. When the washer 5 is fastened to the joint portion 1, the portion 5b of the washer 5 is deformed and comes into close contact with the cap nut 4, as shown in FIG. Only the length L is projected.

FIG. 4 is a partial vertical sectional view showing another embodiment of the joint structure of the present invention, in which the packing 6 is a cap nut 4
P to cover most of the outer peripheral surface 6a and the side surface 6b facing the
It is formed by integrally coating a resin 7 such as TFE. Although not shown in the drawing, instead of integrally coating the resin 7 such as PTFE, a lubricant such as a PTFE coating agent is sprayed on the outer peripheral surface and the side surface facing the cap nut of the packing and assembled. Good.

FIG. 5 is a partial vertical cross-sectional view showing still another embodiment of the joint structure of the present invention, in which the outer peripheral surface 8a of the packing 8 facing the cap nut 4 and the side surface 8b between the cap nut 4 and the outer peripheral surface 8a. Backup rings 9 and 10 for sliding motion are attached.

Next, the operation will be described based on the embodiment shown in FIGS. In any of the joint structures shown in FIGS. 1, 4 and 5, packing 3, 6 or 8 is used.
Is the flare portion 2a of the pipe 2 and the conical outer surface 1a of the joint portion 1.
Is fastened by screwing the cap nut 4 into the male screw 1b of the joint portion 1, so that the fluid inside does not leak from the joint between the pipe 2 and the joint portion 1. Further, the cap nut 4 can be tightened only until the cap nut 4 and the contact portions 4a and 1c provided on the joint portion 1 contact each other. At this time, the packing 3,
Since 6 and 8 are completely tightened, the cap nut 4 is screwed in too much and the packing 3, 6 or 8 is
Will not be damaged and will not stick out, lose its sealing ability or shorten its life.

Further, the packing 3, 6 or 8 is integrally covered with a metal washer 5 so as to cover most of the outer peripheral surface 3a and the side surface 3b as in the embodiment of FIG. In this embodiment, a resin such as PTFE is integrally formed so as to cover most of the outer peripheral surface 6a and the side surface 6b, or a lubricant such as a PTFE coating agent is sprayed on the outer peripheral surface and the side surface instead. Or, as in the embodiment of FIG. 5, by mounting the backup rings 9 and 10 that perform sliding motion between the cap nut 4 and the outer peripheral surface 8a and the side surface 8b at appropriate places, these Packing 3, 6 or 8 depending on function
Does not rotate due to friction with the cap nut 4 when it is tightened, so that no twisting force is generated between the inside and the outside of the packing 3, 6 or 8, and this force damages the packing 3, 6 or 8. There is nothing to do.

In the embodiment shown in FIG. 1, a metal washer 5 is integrally covered so as to cover most of the outer peripheral surface 3a of the packing 3 facing the cap nut 4 and the side surface 3b. The appropriate portion is bent as shown in FIG.
Since the bent portion 5a is formed in the packing 3 as shown in FIG. 1, the washer 5 is extremely firmly attached to the packing 3.

Further, one side of the washer 5 extends up to between the pipe 2 and the cap nut 4, and when the cap nut 4 is tightened, the shape shown in FIG. 3 is deformed before tightening. When the cap nut 4 is screwed in until the contact portion 4a of the cap nut 4 contacts the contact portion 1c of the joint portion 1 as shown in FIG. 1, the end edge portion 5c of the washer 5 causes the cap nut 4 to move. It is configured so as to protrude outward from the end surface 4b by a predetermined length L, the completion of tightening of the cap nut 4 can be visually confirmed, and insufficient tightening can be prevented.

FIG. 6 is a table showing the tightened states of the packing of the present invention and the conventional example. As is clear from the figure, the cap nut 4 is further attached to the male screw 1b from the temporarily tightened state in the present invention. When the contact portion 4a and the contact portion 1c are in contact with each other and the metal touch is made at the point A when the packing 3 is screwed in and the packing 3 is properly tightened, the torque sharply increases as shown by the chain line in the figure. A state in which 3 is excessively crushed and destroyed is surely avoided. On the other hand, according to the conventional example, as shown by the solid line in the same figure, it is tightened more excessively than at the time of proper tightening, and as shown by the line B in the same figure, the packing sticks out and the packing is finally destroyed. Will be done.

[0026]

According to the joint structure of the present invention, the cap nut is properly tightened at the joint portion to prevent leakage surely, the condition of over-tightening the cap nut and damaging the packing is prevented, and further, the cap nut is screwed in. It is possible to prevent the packing from being damaged due to the twisting of the packing due to the rotation and the generation of a torsional load inside, and it is also possible to visually detect that the cap nut is screwed in insufficiently. Have an effect.

[Brief description of drawings]

FIG. 1 is a partial vertical sectional view showing an embodiment of a joint structure of the present invention.

FIG. 2 is a partial perspective view of the washer shown in FIG.

FIG. 3 is a partial vertical cross-sectional view showing a state before the cap nut of the joint structure shown in FIG. 1 is tightened.

FIG. 4 is a partial vertical sectional view showing another embodiment of the joint structure of the present invention.

FIG. 5 is a partial longitudinal sectional view showing still another embodiment of the joint structure of the present invention.

FIG. 6 is a table showing a tightened state of packings of the present invention and a conventional example.

FIG. 7 is a partial vertical sectional view showing an example of a conventional joint structure.

FIG. 8 is a partial vertical sectional view showing another example of a conventional joint structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Joint part 1a Conical outer surface 1b Male screw 1c Abutment part 2 Pipe 2a Flare part 2b Inner surface 3, 6, 8 Packing 3a, 6a, 8a Outer peripheral surface 3b, 6b, 8b Side surface 4 Cap nut 4a Contact part 4b End surface 5 Washer 5a Bend 5c Edge edge

Claims (6)

[Claims] 1. An inner surface of a flare portion formed at the tip of a pipe is superposed on a conical outer surface formed at the tip of a joint portion such as a valve and a pipe joint, and a packing covering the flare portion and the outer surface of the cone is mounted, In a joint structure in which a cap nut is screwed into a male screw formed on the outer peripheral surface of the joint part to seal the packing by tightening, the cap nut and the joint part have an abutting part that abuts when the packing is properly tightened. A joint structure characterized in that each of them is provided. 2. The joint structure according to claim 1, wherein the packing is integrally covered with a metal washer so as to cover an outer peripheral side portion facing the cap nut. 3. The joint structure according to claim 2, wherein a bent portion formed by bending a part of the tip of the washer is embedded in the packing to increase the adhesive force between the packing and the washer. 4. The rear end of the washer extends up to between the pipe and the cap nut, and the washer is deformed by tightening the cap nut so that the rear end edge of the washer is outside the end face of the cap nut. The joint structure according to claim 2 or 3, wherein the joint structure is configured to project toward one side. 5. The joint structure according to claim 1, wherein the packing is formed by integrally coating a resin such as PTFE so as to cover an outer peripheral side portion facing the cap nut. . 6. The backup ring for sliding movement between the packing nut and the cap nut is mounted at an appropriate position on an outer peripheral side portion of the packing facing the cap nut. Joint structure.