JPH11257570A - Fluororesin coupling for fluororesin tubular member passing high temperature fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a fear of removing a fluororesin tubular member by the weight of itself, or by the weight of a fluid passing through the inside, even when the coupling is made of a material with a small friction coefficient such as a fluororesin, and a high temperature fluid flows through the inside. SOLUTION: In this fluororesin coupling, a fluororesin inner sleeve 18 having a diameter expanding part 18b of the outer diameter which is not removed even through a high temperature fluid is passed is provided at the inner side at the fluororesin main body 12 side of a box nut 14, and at least one seal means 12f. 18e/13 is provided so as to seal the fluororesin main body 12 and the inner sleeve 18 perfectly by fastening the box nut 14, while it is connected with a fluororesin tubular member 16 by the welding between the inner sleeve 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluororesin joint used for connecting a fluororesin tubular member through which a high-temperature fluid passes to a fluororesin body using a cap nut.

[0002]

2. Description of the Related Art In recent years, foods, chemicals, semiconductor industry, biotechnology, chemical industry,
The demand for higher quality resins in the residential and gas fields has increased,
PTFE, FEP, PFA, ETFE, CTFE, PV
Fluorine-based resins such as DF have come to be used as piping materials. In order to freely pipe such piping materials, a technique for connecting them is necessary, and one of them is a joint (fitting) using a cap nut.

FIG. 3 is a longitudinal sectional view showing a typical example of a joint using a conventional cap nut. A joint 20 using a conventional cap nut includes a fluororesin main body 22 and a cap nut 24. The main body 22 has a fluid passage 22a penetrating in the axial direction, and has an external thread 22b cut at least on the outer peripheral surface on one side. The cap nut 24 is
A flange 24b having a center hole 24a through which a fluororesin tube 26 to be connected to the center is passed;
And a cylindrical portion 24d having an internal thread 24c screwed into the second male screw 22b.

A method of connecting the tube 26 to the main body 22 using the joint 20 will be described. First, the area near the end of the tube 26 is warmed to increase the diameter, and this is fitted around the one end of the main body 22. Thereafter, the cap nut 24 is screwed into the male screw 22b of the main body 22, and the end of the tube 26 is firmly fixed to one end of the main body 22.

[0005]

The joint 20 has a disadvantage that the seal between the tube 26 and the main body 22 is not sufficient, and the fluid passing through the inside leaks out. Moreover,
Due to the weight of the tube 26 and the fluid passing through the tube 26, the tube 26 is easily pulled out of the main body 22, and depending on the fluid passing through the tube 26, it causes a major accident.

Therefore, the tube 26 is connected to the main body 2 of the joint 20.
Various ideas have been devised in order not to fall out of Step 2. For example, in the joint 30 shown in FIG. 4, a sleeve 38 having an outer peripheral surface having a triangular mountain shape is interposed between the main body 32 and the cap nut 34, and the cap nut 34 is tightened to fix the tube 36 to the sleeve 38. In this joint 30,
There are two routes through which the fluid flowing inside may leak to the outside. The first route R1 is the sleeve 38
This is a route that passes through the gap between the cap nut 34 and the inside of the cap nut 34 and the outside through the center hole 34 a of the cap nut 34. The second route R2 is a route that passes through the gap between the sleeve 38 and the outside of the tube 36 and passes through the inside of the cap nut 34 and the center hole 34a of the cap nut 34 to the outside.

In this joint 30, each route has two sealing portions and excellent sealing characteristics. However, when a high-temperature fluid flows through the inside, the tube 36 and the weight of the fluid passing through the tube 36 cause the tube 36 to be attached. Sleeve 38
The drawback of leaving was the same. This is because the fluororesin has a small coefficient of friction and is easy to slip, and when the joint 30 is heated, each part expands and the space between the tube 36 and each part is loosened.

Further, in the joint 40 shown in FIG. 5, a ring 48 having an arcuate outer peripheral surface is fitted into a predetermined position inside from the end of the tube 46, and this is mounted in a storage recess 42a formed inside the main body 42. Like that. Then, the tube 46 is connected to the main body 42 by tightening the cap nut 44.
Fixed to. In this joint 40, there is one route through which the fluid flowing inside may leak to the outside. Further, by tightening the cap nut 44, the tube 46
Is sandwiched between the accommodating concave portion 42a of the main body 42 and the ring 48, and thus has excellent sealing characteristics. However, when the high-temperature fluid flows through the inside of the joint 40, the disadvantage that the tube 46 comes off from the main body 42 due to the weight of the tube 46 and the fluid passing through the inside remains.

The present invention has been made in view of the above-mentioned problems of the prior art, and is made of a material having a small coefficient of friction, such as a fluororesin, and a high-temperature fluid flows through the inside. It is an object of the present invention to provide a fluororesin joint for a fluororesin tubular member that allows a high-temperature fluid to pass through without causing the fluororesin tubular member to escape due to the weight of the fluid passing through itself and the inside.

Another object of the present invention is to provide a fluororesin joint for a fluororesin tubular member through which a high-temperature fluid passes, wherein the connection with the fluororesin tubular member is achieved by welding. Aim.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a fluororesin joint used for connecting a fluororesin tubular member through which a high-temperature fluid passes to a fluororesin body using a cap nut, wherein the fluororesin of the cap nut is provided. On the inner side of the resin body, a fluororesin inner sleeve having an outer diameter enlarged portion that does not fall off even when a high-temperature fluid is passed is interposed, and by tightening a cap nut, the fluororesin body and the inner sleeve are Wherein at least one sealing means is provided so as to be completely sealed, and the fluororesin tubular member is connected by welding between the inner sleeve and the fluororesin tubular member. Provided is a fluororesin joint for a tubular member.

Due to the presence of the enlarged diameter portion of the inner sleeve,
Even if a high-temperature fluid is passed through the inside of the fluororesin body, there is no danger that the inner sleeve will fall off the cap nut. With at least one sealing means provided, the sealing performance between the fluororesin main body and the inner sleeve, which is the only route that may leak out, can be assured. Of course, the connection between the fluororesin tubular member and the inner sleeve is achieved by welding, so that the seal is complete.

According to a second aspect of the present invention, there is provided a fluororesin body having a fluid passage penetrating in the axial direction and having at least one outer peripheral surface threaded externally, and a fluid passage of the fluororesin body. A fluid passage that communicates with the outer peripheral surface, a central portion having an enlarged diameter portion on the outer peripheral surface, and one end surface is weldable to the tubular member made of fluororesin, and the other end is in contact with the body made of fluororesin. A fluororesin inner sleeve having at least one sealing means, and a female screw screwed into an external thread of the fluororesin main body on the inner peripheral surface, and an inner sleeve expanded at the end on the fluororesin tubular member side. A flange extending inward from the diameter portion, and a cap nut for inserting and fixing the other end of the inner sleeve inside the fluid passage of the fluororesin main body; Providing fluororesin joint for fluororesin tubular member.

After an inner sleeve having an enlarged diameter portion on the outer peripheral surface of the central portion is interposed inside the cap nut, the cap nut is screwed into the fluororesin main body. Due to the presence of the enlarged diameter portion of the inner sleeve, there is no danger that the inner sleeve will fall off from the cap nut even if the high-temperature fluid flows through the inside of the fluororesin body. With at least one sealing means provided, the sealing performance between the fluororesin main body and the inner sleeve, which is the only route that may leak out, can be assured. Of course, the connection between the fluororesin tubular member and the inner sleeve is achieved by welding, so that the seal is complete.

According to a third aspect of the present invention, in the fluororesin joint for a fluororesin tubular member through which a high-temperature fluid is passed, the sealing means of the inner sleeve is provided in the fluid passage of the fluororesin main body. It is a tapered seal achieved by surface contact between the formed inner sleeve mounting recess end surface.

By tightening the cap nut, a stronger surface contact can be obtained and the sealing property is improved.

According to a fourth aspect of the present invention, there is provided a fluororesin joint for a fluororesin tubular member through which a high-temperature fluid is passed according to the third aspect, wherein a counterbore is formed inside the end surface of the fluororesin main body on the inner sleeve side. It is characterized in that an O-ring having elasticity is mounted on the counterbore portion to form a double seal structure.

The double sealing structure further improves the sealing performance. In addition, the elastic O-ring installed in the counterbore can provide a seal that is not affected by the expansion of each component due to a rise in temperature.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fluororesin joint for a fluororesin tubular member through which a high-temperature fluid passes according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a longitudinal sectional view of one embodiment of a fluororesin joint for a fluororesin tubular member through which a high-temperature fluid passes according to the present invention, and FIG. 2 is an exploded longitudinal sectional view thereof.

As shown in FIGS. 1 and 2, a fluororesin joint 10 according to the present invention is schematically illustrated by PFA,
A fluororesin body 12 made of PTFE or the like, a fluororesin inner sleeve 18 made of PFA or the like, and a PFA
And the like. Since the cap nut 14 is not directly exposed to the fluid flowing therein, it is not always necessary to use a fluororesin. However, in consideration of thermal expansion, it is preferable to use substantially the same material as other parts. .

The fluororesin main body 12 is a cylindrical component having a fluid passage 12a penetrating in the axial direction, and has a flange 12b on the outer peripheral surface at the center. Fluororesin body 12
Has an external thread 1 on both sides across the flange 12b.
2c and 12d are cut off. The male screw 12c is for screwing the cap nut 14, and the male screw 12d is for screwing to the equipment for installing the fluororesin joint 10.

A recess 12e for mounting the inner sleeve 18 is formed near the end of the fluid passage 12a on the side of the inner sleeve 18, and the inclined end surface 12f is inclined in an inverted manner. Counterbore 12h inside end surface 12g of fluororesin body 12 on inner sleeve 18 side
Is formed, and an O-ring 13 having elasticity, which will be described later, is mounted on the counterbore portion.

The inner sleeve 18 is a cylindrical part having a fluid passage 18a communicating with the fluid passage 12a of the fluororesin main body 12, and has an enlarged diameter portion 18b having a larger diameter on the outer peripheral surface of the central portion. . Tube 1 of enlarged diameter portion 18b
The sixth side is an inclined surface 18c. On the other hand, the enlarged diameter portion 18
The step b on the fluororesin body 12 side is an end surface 18d perpendicular to the axial direction of the inner sleeve 18, and the end surface 12g of the fluororesin body 12 is in contact with this end surface 18d. Therefore, after the combination, between the fluororesin body 12 and the inner sleeve 18,
A small ring-shaped space having a triangular cross section is formed in the spot facing 12h. In this space, elastic O
The ring 13 is mounted. Even if the fluororesin body 12 and the inner sleeve 18 are heated and expanded, the size of this space does not change, so that the O-ring 13 can always provide constant sealing characteristics.

An inclined surface 18e having the same inclination as the inclined end surface 12f of the fluororesin main body 12 is formed inside the end surface of the inner sleeve 18 on the fluororesin main body 12 side.
The opposite end face 18 f of the inner sleeve 18 is attached to the inner sleeve 1 so that it can be welded to the end face of the tube 16.
8 is formed so as to be substantially perpendicular to the axial direction.

The cap nut 14 is a flange 14 having a center hole 14a through which a fluororesin tube 16 to be connected passes.
b, and a cylindrical portion 14d having an internal thread 14c on the inner peripheral surface that is screwed to the external thread 12c of the main body 12. The cap nut 14 is further provided with a pressing surface 14e having the same inclination as the inclined surface 18c of the inner sleeve 18 between the center hole 14a and the female screw 14c.

Next, a method of using the fluororesin joint 10 will be described. After the inner sleeve 18 having the enlarged diameter portion 18 b having a larger diameter on the outer peripheral surface of the central portion is interposed inside the cap nut 14, the cap nut 14 is screwed into the fluororesin main body 12. At this time, the O-ring 13 is fitted adjacent to the end face 18d of the inner sleeve 18, and when assembled, the O-ring 13 is mounted in the counterbore 12h. Due to the presence of the enlarged diameter portion 18 b of the inner sleeve 18, there is no possibility that the inner sleeve 18 will fall off the cap nut 14 even when a high-temperature fluid is passed through the inside of the fluororesin body 12 and the inner sleeve 18.

When the cap nut 14 is tightened, the slope 18
Since c is pressed by the pressing surface 14e of the cap nut 14, the inclined surface 18e comes into close contact with the inclined end surface 12f of the fluororesin main body 12. On the other hand, also in this case, the end surface 18d of the inner sleeve 18 is the end surface 12g of the fluororesin main body 12.
And come into contact with it. Therefore, after the combination, a small ring-shaped space having a triangular cross section is formed between the fluororesin main body 12 and the inner sleeve 18 at the spot facing 12h. An O-ring 13 having elasticity is mounted in this space. Even if the cap nut 14 is tightly tightened or the fluororesin body 12 and the inner sleeve 18 are heated and expanded, the size of this space does not change, so that the O-ring 13 always provides a certain sealing property. it can.

As described above, in the preferred embodiment of the present invention, there are two types of taper seals, the degree of sealing being adjustable by the amount of tightening of the cap nut 14, and the seal by the O-ring 13 which is not affected by the amount of tightening of the cap nut 14 and temperature change. Because of the heavy sealing structure, it is extremely superior to conventional sealing characteristics. Thereby, the sealing performance between the fluororesin main body 12 and the inner sleeve 18, which is the only route that may leak out, can be completely ensured. Of course, the connection between the fluororesin tubular member and the inner sleeve is achieved by welding, so that the seal is complete.

[0030]

According to the present invention, the fluororesin joint for a fluororesin tubular member through which a high-temperature fluid is passed is provided with an outer diameter that is increased so that it does not fall off even when the high-temperature fluid is passed inside the fluororesin body side of the cap nut. A fluororesin inner sleeve having a diameter portion is interposed, and at least one sealing means is provided so that the fluororesin main body and the inner sleeve are completely sealed by tightening a cap nut. Since the tubular member is connected to the inner sleeve by welding, it is made of a material having a small coefficient of friction, such as a fluororesin, and even when a high-temperature fluid flows inside, the fluororesin tubular member is formed. This has an effect that the member can be completely prevented from coming off due to the weight of the fluid passing through itself and the inside.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of a fluororesin joint for a fluororesin tubular member through which a high-temperature fluid passes according to the present invention.

FIG. 2 is an exploded longitudinal sectional view of the fluororesin joint shown in FIG.

FIG. 3 is a longitudinal sectional view showing a typical example of a joint using a conventional cap nut.

FIG. 4 is a longitudinal sectional view showing an example of improvement of a joint using a conventional cap nut.

FIG. 5 is a longitudinal sectional view showing another example of an improved joint using a conventional cap nut.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Fluororesin joint 12 Fluororesin body 12a Fluid passage, 12b Flange, 12c, 12d
Male thread, 12e recess, 12f inclined end face, 12g
End face, 12h Counterbore 13 O-ring 14 Cap nut 14a Center hole, 14b Flange, 14c Female thread,
14d cylindrical portion, 14e pressing surface 16 tube 18 inner sleeve 18a fluid passage, 18b enlarged diameter portion, 18c inclined surface,
18d end face, 18e slope

Claims (4)

[Claims] 1. A fluororesin joint used for connecting a fluororesin tubular member through which a high-temperature fluid passes to a fluororesin main body using a cap nut, wherein an inner side of the cap nut on the fluororesin main body side. A fluororesin inner sleeve having an outer diameter enlarged portion that does not fall off even when a high-temperature fluid is passed is interposed, and by tightening the cap nut, the fluororesin main body and the inner sleeve are completely sealed. At least one sealing means is provided as described above, and the fluororesin tubular member is connected to the fluororesin tubular member by welding between the inner sleeve and the inner sleeve. Fluororesin fitting. 2. A fluororesin body having a fluid passage penetrating in the axial direction and having at least one outer peripheral surface threaded externally, and a fluid passage communicating with the fluid passage of the fluororesin body. And a central portion having an enlarged diameter portion on the outer peripheral surface, one end surface of which can be welded to the fluororesin tubular member and at least one at the other end contacting the fluororesin body side. A fluororesin inner sleeve having sealing means, and a female screw screwed into an external thread of the fluororesin main body on an inner peripheral surface, and a radially enlarged portion of the inner sleeve at an end on the fluororesin tubular member side. A cap nut having a flange extending more inward than the above, and comprising a cap nut for inserting and fixing the other end side of the inner sleeve inside the fluid passage of the fluororesin main body; Fluororesin joint for fluororesin tubular member. 3. The fluororesin joint for a fluororesin tubular member according to claim 2, wherein the sealing means for the inner sleeve is formed in a fluid passage of the fluororesin body. A fluororesin joint for a fluororesin tubular member through which a high-temperature fluid passes, characterized in that it is a taper seal achieved by surface contact with an end surface of a mounting recess. 4. The fluororesin joint for a fluororesin tubular member according to claim 3, wherein a counterbore is formed inside the end surface of the fluororesin main body on the inner sleeve side. A fluororesin joint for a fluororesin tubular member through which a high-temperature fluid is passed, wherein an O-ring having elasticity is attached to a counterbore portion to form a double seal structure.