JPH0330038B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a pipe joint structure for connecting pipes, particularly when connecting pipes through which a corrosive liquid such as an etching solution such as hydrofluoric acid flows. This invention relates to a suitable pipe joint structure.

[Prior art]

FIG. 1 shows a conventional pipe joint structure of this type. In this figure, 1 is a pipe to be connected, 2 is a joint body, 3 is an annular body, and 4 is a nut, and each of these members 1 to 4 is made of a material with excellent corrosion resistance such as fluororesin. has been done. The annular body 3 has wedge-shaped portions 3a and 3b each having a wedge-shaped longitudinal section formed on the front end side and the rear end side,
And it is fitted near the end of the tube 1. Further, the nut 4 is screwed onto the joint body 2 with the annular body 3 accommodated therein.

When the nut 4 is tightened, the wedge-shaped portion 3b on the rear end side of the annular body 3 bites between the outer peripheral surface of the tube 1 and the tapered surface 4a formed inside the nut 4, and at the same time, the nut 4 is tightened. Yotsute annular body 3
By being pushed in the direction of the joint body 2, the wedge-shaped portion 3a on the distal end side of the annular body 3 also bites into between the outer circumferential surface of the tube 1 and the tapered surface 2a formed inside the joint body 2.

As a result, the wedge-shaped portion 3a is pressed against the outer peripheral surface and the tapered surface 2a of the tube 1, so that the annular body 3
and the tube 1 and between the annular body 3 and the fitting body 2. At the same time, the wedge-shaped portions 3a and 3b are pressed against the outer circumferential surface of the tube 1, so that the annular body 3, as well as the joint body 2 and the nut 4, are fixed to the tube 1.

However, in this conventional pipe joint structure, the wedge-shaped parts 3a and 3b of the annular body 3 are simply connected to the pipe 1.
Only by pressing against the outer circumferential surface of the tube 1
Since the structure is designed to fix the annular body 3 and the joint body 2 against the pipe, the pipe 1 may come off from the annular body 3 and the joint body 2 due to vibration, pressure, heat, etc. acting on the pipe line. There were some drawbacks.

In addition, in this conventional pipe joint structure, the pipe 1
Since there is no mechanism for reliably positioning the annular body 3 at an appropriate position relative to the tube 1, when connecting this pipe joint structure and the pipe 1, one must be careful in positioning the annular body 3 with respect to the pipe 1. However, it also had the disadvantage of poor workability. If the nut 4 is screwed onto the joint body 2 by mistake when the tube 1 is about to come out of the annular body 3 halfway as shown in FIG. As a result, it would easily fall off from the joint body 2.

Figures 3 and 4 show other conventional pipe fitting structures. In these figures, 5 is a pipe to be connected, 6 is a joint body, 7 is a nut, 8 is an annular body provided integrally with the nut 7, and these members 5
8 are made of a material with excellent corrosion resistance such as fluorine resin. Further, the tube 5 is provided with a groove 5a on the outer circumferential surface near one end. Further, the longitudinal section of the annular body 3 is wedge-shaped.

When the nut 7 is screwed onto the joint body 6 and tightened, the tip of the annular body 8 is inserted into the groove of the pipe 5.
a and a part of the inner circumferential surface of the joint body 6, and the tip of the annular body 8 is pressed against the groove 5a and a part of the inner circumferential surface of the joint body 6, so that the annular body 8 and A seal between the pipe 5 and the annular body 8 and the joint body 6 is achieved. At the same time, since the tip of the annular body 8 and the groove 5a are engaged, the pipe 5 is moved to the joint body 6 by vibration, pressure, heat, etc.
There is no possibility of it slipping out. Furthermore, due to the engagement between the annular body 8 and the groove 5a, the annular body 8 is automatically and reliably positioned at an appropriate position with respect to the pipe 5. There is no need to be careful in positioning the annular body 8 with respect to the annular body 5, and work efficiency is greatly improved.

However, in this pipe joint structure, as described above, (i)
(ii) a function of being pressed by the pipe 5 and the joint body 6 to seal between the annular body 8 and the pipe 5 and between the joint body 6; and (ii) being engaged with the groove 5a to prevent movement of the pipe 5 in the axial direction. (a) It is necessary to process the annular body 8, the joint body 6, and the groove 5a with high precision, which reduces the manufacturing cost of the annular body 8 and the joint body 6, and the groove. The processing cost of 5a becomes high.

(b) It is not possible to obtain a good seal between the annular body 8, the pipe 5, and the fitting body 6 by simply tightening the nut 7 by hand;
must be tightened very tightly.

There were other drawbacks.

Furthermore, conventionally, Utility Model Application No. 53-36713 and Utility Model Application No. 57
- As in No. 10580, a flexible sealing material such as a rubber packing or an O-ring is sandwiched between the member corresponding to the annular body, the joint body, and the nut, and only the sealing material performs the sealing function. There was a member corresponding to the annular body that only had the function of preventing the tube from moving in the axial direction, but
This type of conventional joint structure requires a sealing material in addition to the member corresponding to the annular body, which increases the number of parts and increases the cost. When attempting to flow a liquid with a high degree of , impurities tend to accumulate in this stagnation.

(b) The sealing material tends to deteriorate in a short period of time.

(c) Impurities may be leached from the sealing material.

The disadvantage was that the following problems occurred.

[Purpose of the invention]

The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional art, and it eliminates the possibility that the pipe will come out of the joint body due to the effects of vibration, pressure, heat, etc. There is no need for relatively high machining accuracy, and costs can be reduced. Sufficient sealing performance can be obtained by simply tightening the nut by hand, and the sealing material can be manufactured separately from the annular body. It is an object of the present invention to provide a pipe joint structure that is suitable for flowing highly corrosive liquids such as etching liquids such as hydrofluoric acid without the need for a pipe joint.

[Structure of the invention]

The pipe joint structure according to the present invention includes: a hollow joint body made of fluororesin; a male threaded portion formed on the outer periphery of the joint body; a nut made of fluororesin that is screwed into the male threaded portion; An annular body made of fluororesin housed inside the nut, an annular wedge-shaped part having a wedge-shaped longitudinal section formed at the tip of the annular body, and one end of which is connected to the nut and the annular body. and a tube made of fluororesin inserted into the inside of the joint body, and when the nut is tightened, the annular body tries to move together with the nut, and the wedge-shaped part moves against the joint body. In the pipe joint structure that cuts between the inner surface of the tube and the outer circumferential portion of the pipe, the tube includes a groove provided in an annular shape around the outer circumferential portion near the end of the tube, and a groove other than the wedge-shaped portion. is provided on the inner peripheral side of the annular body at a portion thereof, and is engaged with the groove of the tube so that the tube cannot move relative to the annular body at least in the axial direction and in the direction away from the joint body. It has a protrusion.

〔Example〕

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

FIG. 5 is a half-sectional view showing an embodiment of the pipe joint structure according to the present invention, and FIG. 6 is an enlarged sectional view showing the main parts of the embodiment. In these figures, reference numeral 9 denotes a pipe to be connected, which is made of fluororesin with excellent corrosion resistance in order to pass a corrosive liquid such as hydrofluoric acid. A groove 9a having a right triangular cross section is provided in an annular shape around the outer circumference near one end of the tube 9.

Reference numeral 10 denotes an annular body, which is made of a fluororesin having excellent corrosion resistance and being relatively soft, such as PTFE (polytetrafluoroethylene resin). On the inner circumferential side of this annular body 10, a protrusion 10a having a right triangular cross section is provided in an annular manner so as to go around the inner circumference, corresponding to the groove 9a of the tube 9.
a is engaged with the groove 9a. As a result, the tube 9 cannot be moved in the axial direction relative to the annular body 10 and in the direction away from the joint body 11, which will be described later.

Both ends of the annular body 10 are tapered at their outer peripheries. As a result, wedge-shaped portions 10b and 10c having wedge-shaped vertical sections are formed at both ends of the annular body 10.

Reference numeral 11 denotes a joint body, which is made of a relatively soft fluororesin having excellent corrosion resistance, such as PTFE. The joint body 11 has a hollow shape with a fluid passage 12 passing through its center. The joint body 11 also has a male threaded part 11a on the outer periphery of one end, a male threaded part 11b on the outer periphery of the other end, and a hexagonal part 11 on the outer periphery of the central part.
c are provided integrally with each other (the male threaded portion 11a is used to connect the joint body 11 to a member other than the pipe 9). moreover,
A tapered surface 11d corresponding to the wedge-shaped portion 10b of the annular body 10 is formed on the inner peripheral surface of the joint body 11 near the end on the male threaded portion 11b side.

Numeral 13 is a nut, which is made of a relatively hard fluorine resin with excellent corrosion resistance such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin). is provided with a tapered surface 13a corresponding to the wedge-shaped portion 10c of the annular body 10.

In this pipe joint structure as well, the nut 13
is screwed onto the joint body 11 with the annular body 10 accommodated therein. And this Natsu 13
When the nut 13 is tightened, the tapered surface 13a of the nut 13 comes into contact with one of the wedge-shaped parts 10c of the annular body 10, so that the annular body 10 is attached to the joint body 1.
1, the other wedge-shaped portion 10b of the annular body 10 bites between the outer peripheral surface of the tube 9 and the tapered surface 11d of the joint body 11.

As a result, the wedge-shaped portion 10b is strongly pressed against the outer peripheral surface and the tapered surface 11d of the tube 9, and a seal between the annular body 10 and the tube 9 and between the annular body 10 and the joint body 11 is achieved.

In this pipe joint structure, as described above, the protrusion 10a of the annular body 10 is engaged with the groove 9a of the pipe 9, so that the pipe 9 is directed axially with respect to the annular body 10 and away from the joint body 11. Since the tube 9 is not movable, there is no risk that the tube 9 will come off the annular body 10 or the joint body 11 due to vibration, pressure, heat, etc.

Then, the wedge-shaped portion 10b of the annular body 10 bites between the joint body 11 and the outer circumferential surface of the tube 9, thereby creating a seal between the annular body 10 and the outer circumferential surface of the tube 9, and sealing the annular body 10 and the joint body 11. While the protrusion 10a only serves to seal the space between the wedges 10b, the protrusion 10d, the tapered surface 11d and It is not necessary to make the groove 9a highly accurate, and the manufacturing cost of the annular body 10 and the joint body 11 and the machining cost of the groove 9a for the pipe 9 can be reduced, and the nut 1
A sufficient seal between the two parts can be obtained by simply hand-tightening 3.

Furthermore, the engagement between the protrusion 10a and the groove 9a automatically and reliably positions the annular body 10 at an appropriate position with respect to the pipe 9. There is no need to be careful in positioning the annular body 10 relative to the object, and work efficiency is greatly improved.

Furthermore, there is no need to provide a flexible sealing material such as a rubber packing or an O-ring separately from the annular body 10, and the above-mentioned drawbacks of the conventional art can be overcome by providing these sealing materials.

In this type of pipe joint structure, the nut generally needs to be made of a relatively hard material in terms of strength, so let's assume that the annular body 10 is
3, the annular body 10 must also be made of a hard material. Therefore, if the pipe 9 and the joint body 11 are also made of hard materials, the contact between the annular body 10 and the pipe 9 and the joint main body 11 will be between hard materials. In order to obtain a good seal, it is necessary to make the tightening force of the nut 13 relatively large and to make the grooves 9a of the annular body 10 and the pipe 9 highly accurate. However, in this embodiment, since the annular body 10 is separate from the nut 13, the above-mentioned inconvenience can be avoided.

Further, the protrusion 10a of the annular body 10 and the tube 9
The cross-sectional shape of the groove 9a does not necessarily have to be the shape shown in FIGS. 5 and 6, but may be, for example, an isosceles triangular shape as shown in FIG. 7 or as shown in FIG. It may be semi-cylindrical, and in short, these shapes prevent the tube 9 from moving relative to the annular body 10 at least in the axial direction and in the direction away from the joint body 11 when the protrusion 10a and the groove 9a are fitted together. Any shape is fine.

FIG. 9 is a half sectional view showing still another embodiment of the pipe joint structure according to the present invention, and FIG. 10 is an enlarged sectional view showing the main parts of this embodiment. In these figures, 15 is a pipe to be connected, which is made of a material with excellent corrosion resistance such as fluororesin, and has a groove 15a (first
(see Figure 0) is provided in an annular shape so as to go around the outer periphery.

Reference numeral 16 denotes a joint body, which is made of a relatively soft fluororesin having excellent corrosion resistance, such as PTFE. The joint body 16 has a hollow shape with a fluid passage 17 passing through its center. The joint body 16 also has a male threaded part 16a on the outer periphery of one end, a male threaded part 16b on the outer periphery of the other end, and a hexagonal part 16 on the outer periphery of the central part.
c are each provided integrally. moreover,
The inner circumferential surface of the joint body 16 near the end on the male threaded portion 16b side forms a curved surface 16d.

A nut 18 is made of fluororesin such as PFA, and an annular body 19 is provided inside the nut 18 integrally with the nut 18. At the tip of the annular body 19, a wedge-shaped portion 19a having a wedge-shaped longitudinal section and a protrusion 19b also having a wedge-shaped longitudinal section are bifurcated and integrally provided on the annular body 19. . Note that the wedge-shaped portion 19a is located on the outer peripheral side of the annular body 19, and the protrusion 19b is located on the inner peripheral side.

In this embodiment, the nut 18 is connected to the joint body 1.
When the wedge-shaped portion 19a is screwed into the external threaded portion 16b of the tube 15 and tightened, the wedge-shaped portion 19a bites between the outer peripheral surface of the tube 15 and the curved surface 16d of the joint body 16, thereby creating a seal between the annular body 19 and the tube 15. At the same time that a seal is achieved between the annular body 19 and the joint body 16, the protrusion 19b is engaged with the groove 15a of the pipe 15 to prevent movement of the pipe 15 in the axial direction and away from the joint body 16. become.

Also in this embodiment, the wedge-shaped portion 19
a only functions to seal between the annular body 19 and the outer peripheral surface of the tube 15 and between the annular body 19 and the joint body 16, and the protrusion 19b only functions to prevent the tube 15 from moving in the axial direction. Therefore, the wedge-shaped portion 19a, the protrusion 19b, the curved surface 16d and the groove 15
It is not necessary to make the machining accuracy of a high precision, and the manufacturing cost of the annular body 19 and the joint body 16 and the pipe 1 are reduced.
The manufacturing cost of the groove 15a for the groove 15a can be reduced, and the sealing between the two parts can be made sufficient just by tightening the nut 18 by hand.

Furthermore, due to the engagement between the annular body 19 and the groove 15a,
Since the annular body 19 is automatically and reliably positioned at an appropriate position with respect to the tube 15, there is no need to be careful in positioning the annular body 19 with respect to the tube 15, and work efficiency is greatly improved.

Furthermore, there is no need to provide a flexible sealing material such as rubber packing or an O-ring separately from the annular body 19.

〔Effect of the invention〕

As described above, the pipe joint structure according to the present invention includes a portion for sealing between the annular body and the outer circumferential surface of the pipe and a seal between the annular body and the joint body, and a part for sealing between the annular body and the nut and the joint body. By providing a separate part from the part that prevents movement in the axial direction, (a) there is no risk of the pipe coming off from the joint body due to the effects of vibration, pressure, heat, etc.

(b) It is not necessary to make the annular body, the joint body, and the pipe relatively highly accurate, and costs can be reduced.

(c) Sufficient sealing performance can be obtained by simply tightening the nut by hand.

(d) There is no need to provide a sealing material separately from the annular body, and it is suitable for flowing highly corrosive liquids such as etching liquids such as hydrofluoric acid.

This provides an excellent effect.

[Brief explanation of the drawing]

FIG. 1 is a half-sectional view showing a conventional pipe joint structure, FIG. 2 is a cross-sectional view showing a state in which the pipe is about to come out of the annular body in the conventional pipe joint structure, and FIG.
The figure is a half-sectional view showing another conventional pipe joint structure.
The figure is an enlarged sectional view showing a part of the conventional pipe joint structure, FIG. 5 is a half sectional view showing an embodiment of the pipe joint structure according to the present invention, and FIG. 6 is a main part of the embodiment. An enlarged sectional view, FIGS. 7 and 8 are sectional views showing other embodiments of the shapes of the protrusion of the annular body and the groove of the pipe, and FIG. 9 shows still another embodiment of the pipe joint structure according to the present invention. The half-sectional view and FIG. 10 are enlarged sectional views showing essential parts of the embodiment. 9...Pipe, 9a...Groove, 10...Annular body, 10
a...Protrusion, 10b...Wedge-shaped portion, 11...Joint body, 11a, 11b...Threaded portion, 13...Nut, 15...Pipe, 15a...Groove, 16...Joint body, 16a, 16b ...Threaded part, 18... Nut, 19... Annular body, 19a... Wedge-shaped part, 1
9b... Protrusion.

Claims (1)

[Scope of Claims] 1. A hollow joint body made of fluorine resin, a male threaded portion formed on the outer periphery of this joint body, a nut made of fluorine resin that is screwed into this male threaded portion, and this An annular body made of fluororesin that is separate from the nut and housed inside the nut; and a pipe made of fluororesin inserted into the nut, the annular body, and the joint body at one end, and when the nut is tightened. , in a pipe joint structure in which the annular body tries to move together with the nut and the wedge-shaped part bites between the inner surface of the joint body and the outer circumference of the pipe, A groove is provided in an annular shape so as to go around the outer circumferential part, and a groove is provided in the inner circumferential side of the annular body so as to form a separate part from the wedge-shaped part, and the pipe is provided in the groove in the annular shape. A pipe joint structure comprising: a protrusion that is engaged with the body so as to be immovable at least in the axial direction and in the direction away from the joint body. 2. A hollow joint body made of fluorine resin, a male threaded portion formed on the outer periphery of this joint body, a nut made of fluorine resin that is screwed into this male threaded portion, and a corresponding one on the inside of this nut. An annular body made of fluororesin formed integrally with the nut, and an annular wedge-shaped body formed at the tip of this annular body, the longitudinal section of which is wedge-shaped and continuous over the entire circumference. and a tube made of fluororesin, one end of which is inserted into the nut, the annular body, and the joint body, and when the nut is tightened, the annular body moves together with the nut. In a pipe joint structure in which the wedge-shaped part bites between the inner surface of the joint main body and the outer circumference of the pipe, the wedge-shaped part is provided with an annular shape around the outer circumference near the end of the pipe. a groove provided on the inner circumferential side of the annular body so as to form a separate part from the wedge-shaped portion; A pipe joint structure comprising a projection that is engaged so as to be immovable in a direction away from the joint body.