JPH1122884A - Device for connecting joint metal fitting with tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connecting device which connects a joint metal fitting with a tube, for use with high pressure resistance. SOLUTION: This device for connecting a joint metal fitting with a tube is provided at its socket 10 with an axial extension pipe 12, an external thread 17 for screwing into place a nut member 20 surrounding the extension pipe 12 in a cylindrical shape, a maximum outside diameter part 13 provided in the extension pipe 12 and located near a mid-position along the extending direction, an inclined pipe part 14 which decreases in diameter toward the extended end of the extension pipe from the maximum outside diameter part 13, and a small-diameter pipe part 15 stepped toward the root. In this case, the nut member 20 is provided with both an internal thread at one end which meshes with the external thread 17 of the socket 10 and an inclined cylinder part which surrounds the inclined pipe part 14 of the extension pipe 12 to tighten both the inclined pipe part 14 and the tube 10 radially, and a hermetic sealing member 41 which is resiliently engaged with the inner peripheral surface of the tube is assembled to the inclined pipe part 14. A ring washer 42 which fastens the end of the tube 30 to the small diameter pipe part 15 of the extension pipe by driving the nut member 20 in is mounted on the end of the tube 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a tube (tube) joint, and more particularly, to a tube made of a resin for flowing a fluid and a joint fitting used for connecting the tube to another device or the like. The present invention relates to a connecting device for connecting a tube of a connecting pipe to a fitting, and more particularly to a connecting device for connecting a fitting of a high-pressure connecting tube to a tube.

[0002]

2. Description of the Related Art Conventionally, when a pressurized fluid is supplied from a pressure source device such as a compressor to a working device for performing nailing or the like using a pressurized fluid (pressurized air or the like), a spiral fiber or the like is embedded to reinforce the pressure resistance. A connection pipe using a flexible resin tube is used. This connection pipe is composed of a tube and a joint fitting connected to an end of the tube, and the joint fitting is used for connection with a working device, a pressure source device, and the like.

[0003] The above-mentioned joint fitting is generally used for making a plug-socket type connection. For example, a plug-type joint fitting is connected to one end of a tube, and a socket-type joint fitting is connected to the other end. It is made a connection pipe. Of these, plug-type fittings (hereinafter simply referred to as "plugs")
Is used to open the built-in normally-closed valve and open the flow path of the pressurized fluid by being inserted into a normally-closed valve built-in socket-type connecting portion provided on the pressure source device side, while the socket-type is used. A joint fitting (hereinafter simply referred to as a “socket”) is used to form a flow passage by fitting a plug-type connection portion on the working device side. The socket is usually assembled with a connection jig called an adapter which has a normally-closed valve and can be connected to the working device with one touch.

[0004] Incidentally, the joint fitting and the tube as described above need to be firmly connected so as not to come off. For example, Japanese Utility Model Publication No. 6-19905 and Japanese Utility Model Publication No. 6-2.
A structure described in Japanese Patent No. 3825 is conventionally known.

[0005] In the connecting device described in Japanese Utility Model Publication No. 6-19905, a tube extending along the axial direction of the socket body is a straight tube into which the tube end is inserted without particularly increasing the diameter. , A cylindrical member having a cylindrical inclined cam surface whose inner diameter gradually decreases in the tube withdrawing direction is fixed to the socket main body, and a stopper member capable of reducing the diameter is formed between the straight tube and the cylindrical member. The stopper is engaged with the outer periphery of the tube by pulling in a pull-out direction after the tube is externally fitted to the base of the straight tube, and then pulled in the drawing direction. The diameter is forcibly reduced by the inclined cam surface of the shaped member, and the member is fastened to the straight pipe to perform connection.

[0006] This connecting device is excellent in that the connection between the fitting and the tube can be relatively easily performed, and the engagement can be released, so that the tube can be easily replaced. However, there is a problem that the structure is complicated and the number of parts is large, and if the stopper member is loosened due to an impact or the like, the tube may come off.

In the connecting device described in Japanese Utility Model Publication No. Hei 6-23825, a pipe part extending along the axial direction of the socket is formed as a slanted pipe whose outer diameter gradually decreases toward the tip of the extension. Fit the end of the tube, cover the nut member on the outside, screw it into the socket, and clamp the tube in the radial direction with the nut member and the inclined tube, and bend the tube end outward by approximately 90 °. The tube end which is widened and expanded outward by the stepped portion of the nut member and the socket is axially pressed to prevent the tube from falling off.

In this connecting device, the distal end of the tube is bent outwardly and is strongly pinched in the axial direction between the socket body and the nut member to prevent the tube from coming off. However, the connecting device tends to return to a natural state (normal diameter state). There is no way to confirm the state when the end of the tube having the function is forcibly bent in the direction of the axis while being forcibly bent and spread outward by about 90 °, or the state after the clamping operation is performed. There is a problem that the reliability of whether a reliable connection state can be secured is not sufficient.

[0009]

By improving the conventional connecting device for connecting a fitting to a tube in a connecting pipe as described above, the number of parts can be reduced and the connection can be reliably performed by a simple operation. FIG. 6 shows an example of a connection device that can ensure reliability.

In the example shown in FIG. 6, a tube 70 is connected to a socket 50 by using a nut member 60. The socket has a fluid passage 51 at an axial center portion and has a cylindrical structure as a whole. Reference numeral 50 denotes an extension tube 52 extending from one end thereof along the axial direction, and a maximum outer diameter portion 53 (the insertion tube having a diameter slightly larger than the tube inner diameter is expanded near the middle of the extension). The outer diameter is gradually reduced toward the distal end, and the inclined tube 54 extends from the maximum outer diameter portion 53 toward the distal end, and is stepped from the maximum outer diameter portion 53. The small-diameter portion 55 is provided in a structure reaching the base of the extension pipe 52. Reference numeral 56 denotes an abutting wall at the tip of the tube, and
It hits when it is inserted to the root of. Reference numeral 57 denotes a male screw portion for screwing in a nut member provided on the peripheral surface at a position larger in diameter than the abutting surface 56 and having a fixed length in the axial direction. Reference numeral 58 denotes an adapter fixing screw portion for screwing and fixing an adapter (not shown).

On the other hand, the nut member 60 is provided in a cylindrical structure having an inner cylinder provided with a step in the axial direction, and the dimension of the small-diameter cylinder portion 61 is substantially equal to the outer diameter of the tube 70. And the large-diameter cylindrical portion is provided with a female screw portion 62 that is screwed into the male screw portion 57 of the socket 50.

In the above configuration, first, the tube 70
Is inserted until its tip reaches the abutting wall surface 56 at the base of the extension tube 52 of the socket 50. At this time, the tube 70
Is gradually expanded by the inclined tube portion 54 in accordance with the insertion and push-in, but after engaging the maximum outer diameter portion 53, it engages with the small diameter portion 55 by the action of returning to the natural state (normal diameter state). Thus, although the diameter is increased by the inclined tube portion 54, the state of being fitted into the extension tube 52 can be maintained almost stably in the axial direction.

Therefore, in this state, even if the operation of screwing the nut member 60 provided on the tube 70 into the socket 50 is performed, the tube 70 remains in the socket 50 (extending tube 52).
The screw is not subjected to any action in the direction of coming out of the tube, and by this screwing, the small-diameter cylindrical portion 61 of the nut member 60 having a size substantially matching the outer diameter of the tube 70 and the tube having a larger diameter than the inner diameter of the tube 70 are used. Maximum outer diameter portion 53 to be expanded
The tube 70 can be securely clamped in a narrow path not more than the wall thickness of the tube 70 while maintaining airtightness. The distal end of the tube can be reliably prevented from falling off by being hooked on the maximum outer diameter portion 53 which is stepped to the small diameter portion 55 of the extension tube.

By adopting such a structure of the connecting device shown in FIG. 6, the conventional connecting device in which the distal end of the tube is bent outwardly by about 90 ° and is strongly sandwiched in the axial direction between the socket and the nut member. However, it is difficult to obtain a high reliability because the action of forcibly expanding the end of the tube to return to the natural state is contrary to the secure securing of the retaining state, whereas the connecting device of FIG. There is provided a coupling device which is easy to assemble and has a high reliability while having a small number of parts without being adversely affected by the action of returning to the natural state.

By the way, the connecting device shown in FIG.
Although it has a highly reliable structure for a pressure-resistant connecting pipe through which a pressure fluid of about 7 to 10 kg / cm ² flows, it is used as a connecting device for a connecting pipe used at a high pressure such as ²⁰ to 25 kg / cm ^2. Are not sufficient in ensuring airtightness and preventing the tube from coming off. For this reason, conventionally, in order to secure mechanical strength such as high pressure resistance, a caulking type connection structure for fixing a tube by plastically deforming a fitting is generally adopted.

However, the caulking-type connection structure has a problem that when it is necessary to repair or replace a tube or a fitting, it is not easy to release the connection, and the entire connection pipe must be replaced. .

An object of the present invention is to provide a coupling device which can be engaged and disengaged under such a conventional technique.

Another object of the present invention is to provide a highly reliable connecting device which can secure excellent airtightness and secure the tube from coming off as a connection tube for high pressure resistance.

Still another object of the present invention is to use a low-cost PVC resin tube, which does not hydrolyze, as a pressure-resistant connecting tube, because it does not hydrolyze. It is an object of the present invention to provide a joint fitting and tube connecting device that can be reliably secured.

[0020]

The above-mentioned object is achieved by the joint fitting and tube connecting apparatus of the present invention described in the claims.

[0021] The invention of a connecting device according to claim 1 of the present application is an apparatus for connecting a fitting and a tube, wherein a tube extending in an axial direction for externally inserting a tube end into the fitting is provided; A male screw for fixing a cylindrical nut member to be screwed and fixed to the fitting fitting by being externally fitted to the tube so as to surround the extension tube is provided, and the extension tube has an intermediate portion in the extension direction. A sloped tube portion whose outer diameter is gradually reduced from the largest diameter portion to the extended distal end side to expand the insertion tube formed near the position, and a stepped small diameter tube portion from the largest diameter portion to the extended base side. The cylindrical nut member is provided at one end thereof with a female screw to be screwed to the male screw of the joint fitting, and a tube is formed together with the inclined pipe part around the inclined pipe part of the fitting fitting extension pipe. Is provided with a slanted cylinder that tightens radially
Further, a seal member that elastically engages with the inner circumferential surface of the tube and is hermetically sealed is assembled to the inclined tube portion of the fitting, and the distal end of the tube is pressed by the inclined tube portion by screwing the nut member. A ring washer for fastening the distal end of the tube to the small-diameter tube portion of the extension tube by reducing the diameter is provided.

In the above structure, the fittings made of metal such as stainless steel are not limited, but the above-mentioned sockets and plugs are exemplified. As described above, an adapter is often attached to a socket in many cases.

The size of the maximum outer diameter portion formed on the extension tube in the above configuration is not limited, but a case where the diameter of the tube is set to be enlarged by about 1/2 of the wall thickness is mentioned. Can be. Further, the degree of inclination of the inclined pipe portion which gradually decreases in the distal direction from the maximum outer diameter portion of the joint fitting extension tube is not particularly limited as long as the insertion of the tube is not hindered. For example, the inclination is gentle with a gradient of about 1 to 3/10. Is inclined.

According to the present invention, a highly airtight and highly reliable connecting device can be obtained mainly by a sealing member such as an O-ring while the number of parts is small and the assembling work is easy. As a pressure-resistant connecting tube, the tube can be reliably prevented from coming off mainly by radially tightening the inclined surfaces inside and outside the tube and by tightening the ring washer.

According to a second aspect of the present invention, in the above-mentioned invention, a retaining member is provided on the inner peripheral surface of the inclined cylindrical portion in which the inner peripheral diameter of the nut member is gradually reduced so as to engage with the outer peripheral surface of the tube in the axial direction. The invention of claim 3 is characterized in that the retaining is a female screw, and the screw pitch of the female screw is set to the same pitch as the female screw of the nut member screwed to the male screw of the fitting. I do.

According to these inventions, the tube is reliably prevented from coming off by the axial unevenness stopper provided on the outer peripheral surface of the tube. In particular, when the stopper is a female screw, this female tube is attached to the outer periphery of the tube. Since the resistance when the screw bites is the same as the screwing direction in which the nut member is screwed into the socket, the screwing operation is smooth and easy, but the axial locking action is reliably obtained.

In each of the above-mentioned inventions, the tube is formed of, for example, a PVC resin, a urethane resin, or the like, and a PET fiber having a spiral shape or an axially extending PET fiber for high pressure resistance is formed of the tube. The one that is buried in the resin thickness to prevent swelling of the pipe is used,
The invention of the connecting device according to claim 4 of the present application is characterized in that a tube made of a PVC resin is used, whereby a low-cost connecting tube excellent in weather resistance can be provided.

For the PVC resin tube, for example, a known PVC resin used for a connection pipe can be used.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments shown in the drawings.

Embodiment 1 In the present embodiment shown in FIGS. 1 to 4, a tube 30 is connected using a socket 10 and a nut member 20.
As shown in FIGS. 1 and 3, a socket 10 having a fluid passage 11 at an axis portion and having a cylindrical structure as a whole has an extension tube 12 extending from one end thereof in the axial direction. And the maximum outer diameter portion 13 near the middle of the extension.
(Set to a size slightly larger than the inner diameter of the tube so as to expand the insertion tube) and extend from the maximum outer diameter portion 13 to gradually decrease the outer diameter toward the distal end toward the distal end. 14, and a small-diameter tube portion 15 is provided in a range from the maximum outer diameter portion 13 to the base of the extension tube 12 stepped. Further, a peripheral groove 141 is provided in the inclined tube portion 14, and an O-ring 41 as a sealing member is fitted so as to elastically engage with the inner surface of the tube.

Numeral 16 denotes a wall to which the tube tip is abutted, which is abutted by inserting the tube 30 to the base of the extension tube 12. Reference numeral 17 denotes a male screw portion for screwing in a nut member provided on the peripheral surface at a position larger in diameter than the abutting surface 16 with a fixed length in the axial direction. Reference numeral 18 denotes an adapter fixing screw portion for screwing and fixing an adapter (not shown). Reference numeral 19 denotes an overhang portion that protrudes in a conical shape in the axial direction from the peripheral edge of the abutting wall surface 16, and is provided so that the diameter of a ring washer 42 described later can be reduced by the conical slope.

On the other hand, the nut member 20 is provided in a cylindrical structure as shown in FIGS.
Is set to a size substantially matching the outer diameter of the tube 30, and the large-diameter cylindrical portion 22 is provided with the socket 10.
The female screw part 221 to be screwed with the male screw part 17 is formed. At an intermediate position between the small-diameter portion 21 and the large-diameter portion 22, there is provided an inclined tubular portion 23 whose inner diameter gradually decreases toward the small-diameter portion side. The inclined tubular portion 23 has a female screw for biting the outer peripheral surface of the tube. A part 231 is formed. In this example, the inclination of the inclined cylindrical portion 23 is provided so as to substantially coincide with the inclined tube portion 14 of the socket, and the screw pitch of the female screw portion 231 is the same as that of the female screw portion 221. I have.

The operation of assembling the nut member 20 to the assembly composed of the socket 10, the tube 30 and the like configured as described above to form a connecting device will be described with reference to FIGS.

First, the tube 30 is inserted until the tip of the tube 30 reaches the abutting wall 16 at the base of the extension tube 52 of the socket 10. At this time, the diameter of the tube 30 is gradually increased by the inclined tube portion 14 as the tube 30 is inserted and pushed.
After having passed through the inclined pipe portion 14, the small diameter portion 15 is engaged by the action of returning to a natural state (a state of a normal diameter).
However, the state of being fitted into the extension pipe 52 can be maintained almost stably in the axial direction.

Next, the ring washer 42 mounted on the tube 30 is pushed down to the tip of the tube 30. The ring washer 42 is made of a C-shaped leaf spring material in which a metal plate such as stainless steel is cut by a slit at a part in the circumferential direction. Can be.

The nut member 20 covered with the tube 30 is axially pushed into the assembly in this state (see FIG. 2A). At this time, the tube 30 is not affected at all in the direction in which the tube 30 comes out of the socket 10 (extended tube 12).

After the nut member 20 is pushed into the state shown in FIG. 2A and the female screw portion 221 of the nut member 20 is engaged with the male screw portion 17 of the socket 10, the nut member 20 is rotated so as to be screwed. . When this screwing rotation proceeds by a certain length, the inclined cylindrical portion 23 comes into contact with the outer peripheral surface of the tube 30 whose diameter has been increased (see FIG. 2B), and then the screwing operation is further performed, whereby the inclined cylindrical portion 23 is advanced. The gap between the tube 23 and the inclined pipe portion 14 of the socket gradually narrows, and the tube 30 is screwed to the final stage, so that the tube 30 is securely clamped in a narrow path whose thickness is not more than the wall thickness. The state shown in FIG. 1 is obtained in which the inner peripheral surface is elastically pressed and engaged to ensure high airtightness.

In the nut member 20 of the present embodiment, the female thread 231 provided on the inclined cylindrical portion 23 is provided at the same pitch as the screw pitch of the threaded screw portion of the socket 10 and the nut member 20. At the time of screwing the member 20, the screw can be smoothly screwed without receiving a large resistance in the axial direction.
Is engaged with the tube 30 in the axial direction, so that each of them can be prevented. In addition to this, in this example, the ring washer 42 provided at the tip of the tube 30 is attached to the inclined cylindrical portion 23 and the overhang portion 19 of the socket with the screwing of the nut member 20.
With this inclined surface, the diameter is forcibly reduced toward the inside of the diameter, so that a more reliable retaining can be achieved.

By adopting the structure of the connecting device of this embodiment,
There is no disadvantageous effect due to the effect of the expanded tube returning to the natural state, and the assembly tube is easy to assemble with a small number of parts, and a connection tube for high pressure resistance can be obtained with high reliability.

Embodiment 2 In this embodiment, as shown in FIG.
0, and is different from the first embodiment only in that the joint fitting main body has a plug structure, and the structure of a portion connecting other tubes is substantially the same. Is shown by adding 100 to the reference numerals in FIG. 3 and the description is omitted.

In this example, the plug 110 and the tube, which are the fittings, can be easily assembled with a small number of parts and the connection tube for high pressure resistance can be formed in a highly reliable manner in the same manner as in the first embodiment. Obtainable.

[0042]

【Example】

Example 1 A connection pipe having the connection device of the first embodiment described with reference to FIGS. 1 to 4 was tested under the following conditions.

Joint fitting: Socket (made of stainless steel) Extension tube Tube length: 18.5 mm Maximum outer diameter portion: Outside diameter 8.0 mm Inclined tube length: 10 mm Small diameter tube length: 8.5 mm Screwed male screw: Outside diameter 15mm screw fixing male screw part: shaft length 6mm Nut member: (stainless steel) Tube length: 27mm screw fixing female screw part inner diameter 15mm shaft length 8mm inclined cylinder female screw part inner diameter 13mm shaft length 9mm small diameter part inner diameter 10.8mm shaft Length 7mm Tube: (PVC resin: Reinforcing fiber embedded structure) Outer diameter 4.8mm Inner diameter 10.5mm (Cycle hermeticity test) Test sample (tube length) 1 m) in an atmosphere at a temperature of 80 ° C. for 12 hours, and then for 12 hours under normal-temperature pressurization (air pressure: 38 kgf / cm ² ). The cycle was followed by immersion immediately in water at 80 ° C. to check for air leakage. In the test, the above operation was performed for each of two test samples, one cycle, two cycles, and three cycles. The results are shown in Table 1 below.

[0044]

[Table 1]

(Pull-Out Test) A pull-out test was performed on a test sample to which a tube having a length of 100 mm was connected under the following conditions, and the pull-out strength (kgf / piece) at the time when the tube was pulled out was determined by Autograph IS-2000.
(Manufactured by Shimadzu Corporation). The test was performed on each of two test samples. The results are shown in Table 2 below.

Tension speed: 50 mm / min Measurement temperature: (a) 23 ° C., no internal pressurization (b) 80 ° C. × 15 minutes, internal pressurization at 30 kgf / cm ²

[0047]

[Table 2]

(Rupture test) With respect to a test sample to which a tube having a length of 1 m was connected, the internal pressure was increased at a temperature of 25 ° C. and 80 ° C., and the pressure (kgf / cm
² ) investigated. The test was performed on each of two test samples. The results are shown in Table 3 below.

[0049]

[Table 3]

The rupture at 80 ° C. in Table 3 occurred in such a manner that the reinforcing fiber was not ruptured and the resin portion of the tube burst in a pinhole state.

(Low-temperature airtight test) A test sample to which a tube having a length of 1 m was connected was taken out after being kept in a temperature atmosphere of -20 ° C for 24 hours, and an internal pressure of 38 kgf / cm ² was applied to check for air leakage. confirmed. The leak was confirmed underwater. The test was performed on each of two test samples. The results are shown in Table 3 below.

[0052]

[Table 4]

Example 2 The above tests were performed in the same manner as in Example 1 except that the dimensions of the fittings were changed as described below, and the results are shown in Tables 1 to 4 above.

13. Extension tube maximum outer diameter part: outer diameter 9.5 mm screwing fixed male screw part: outer diameter 17 mm nut member: (made of stainless steel) screwing fixed female screw part inner diameter 17 mm inclined cylinder female screw part inner diameter 2 mm Small diameter portion Inner diameter 12.3 mm Tube: (made of PVC resin: Reinforcing fiber embedded structure) Outer diameter 6.0 mm Inner diameter 12.0 mm Comparative example 1 The coupling device described in FIG. Under the same conditions as in Example 1, a test (cycle airtight test) and a test (pull-out test) were performed. The socket and the tube of the connecting device were the same as those of the first embodiment, and the nut member was the same as that of the first embodiment except that the inner cylindrical portion was configured as follows. The results are shown in Tables 5 and 6 below. Nut member: (made of stainless steel) Small diameter part Inside diameter 11.0mm Shaft length 16mm

[0055]

[Table 5]

[0056]

[Table 6]

Comparative Example 2 The above tests were performed in the same manner as in Comparative Example 1 except that the dimensions of the fittings were changed as described below, and the results are shown in Tables 5 and 6 above.

Nut member: (made of stainless steel) Small diameter portion Inner diameter 12.5 mm As can be seen from these tables, the connection work of any connection device can be performed more easily and reliably than the conventional one. Moreover, the connection device of the first embodiment is almost the same as the connection device of FIG. 6 in terms of pressure-resistant strength, although it is almost the same in that high reliability can be obtained in the formation of the target structure. It can be seen that the above is also excellent.

[0059]

As described above, according to the connecting device of the present invention, while the coupling member and the tube can be disengaged by attaching and detaching the nut member, the coupling member is mainly elastically engaged with the peripheral surface of the sealing member without the tube. As a result, a highly airtight and highly reliable connecting device can be obtained, and the connection tube for high pressure resistance can be securely removed by mainly tightening the inner and outer slopes of the tube in the radial direction and the ring washer. The excellent effect that it can be prevented is exhibited.

According to the second aspect of the present invention, wherein the inner peripheral surface of the nut member is provided with a stopper that engages with the concave and convex portions, the tube is reliably prevented from coming off, and in particular, the stopper is a female screw. According to the third aspect of the present invention, since the resistance when the female screw bites into the outer circumference of the tube is the same as the screwing direction in which the nut member is screwed into the socket, the screwing operation is smooth and easy, while the screwing operation is easy. The effect is obtained that the retaining in the direction can be reliably obtained.

According to the fourth aspect of the present invention, a high-pressure-resistant connecting pipe is made of a PVC resin tube which is excellent in weather resistance and is low in cost because it is not hydrolyzed. Sex can be ensured.

[Brief description of the drawings]

FIG. 1 is a side view showing a configuration of a coupling device for connecting a joint fitting and a tube according to a first embodiment of the present invention, in which an upper half of a center line is sectioned.

FIGS. 2A and 2B are cross-sectional views of an upper half of a center line for explaining a connecting operation of the connecting device of FIG. 1; FIG. 2A is a state before a nut member reaches a screwing position; This shows a state in which screwing has been started.

FIG. 3 is a vertical side view of the socket of FIG. 1;

FIG. 4 is a longitudinal sectional side view of the nut member of FIG. 1;

FIG. 5 is a side view showing a plug which is a joint fitting according to a second embodiment of the present invention, and shows a cross section of an upper half of a center line.

FIG. 6 is a side view showing a configuration of a coupling device for connecting a fitting and a tube according to a comparative example, in which an upper half of a center line is sectioned.

[Explanation of symbols]

10 ... socket, 11 ... fluid passage, 12 ...
Extension tube, 13: maximum outer diameter portion, 14: inclined tube portion,
141 ... peripheral groove, 15 ... small diameter tube part, 16 ... butting wall surface, 17 ... male screw part, 18 ... adapter fixing screw part, 19 ... overhang part, 20.・
· Nut member, 21 ··· small-diameter tube portion, 22 ··· large-diameter tube portion, 221 ··· female thread portion, 23 ··· inclined tube portion, 23
1 ... female screw part, 30 ... tube, 41 ... O
-Ring, 42 ... ring washer.

Claims (4)

[Claims] 1. An apparatus for connecting a joint fitting to a tube, wherein a tube extending in an axial direction for externally inserting a tube end into the joint fitting, and a tube surrounding the extension tube. And a male screw for fixing a cylindrical nut member to be screwed and fixed to the fitting by being externally fitted to the fitting, and the extension tube is provided with a fitting tube formed near an intermediate position in the extension direction. The cylindrical nut member is provided with a slanted tube portion in which the outer diameter from the largest diameter portion to be enlarged to the extension tip side is gradually reduced, and a stepped small diameter tube portion from the largest diameter portion to the extension base side. In addition, a female screw that is screwed into the male screw of the fitting is provided on one end side, and an inclined cylindrical portion that surrounds the inclined tube of the fitting extending tube and radially tightens the tube together with the inclined tube is provided. Further, an inclined tube portion of the joint fitting is provided with an inner peripheral surface of the tube. At the same time, a sealing member is fitted and hermetically sealed by fitting and engaging, and at the tip of the tube, the nut is screwed into the slanted tubular portion to reduce the diameter of the tube. A coupling device for connecting a fitting and a tube, wherein a ring washer for tightening the outer surface is provided. 2. The joint according to claim 1, wherein a retaining member is provided on an inner peripheral surface of the inclined cylindrical portion in which an inner peripheral diameter of the nut member is gradually reduced so as to engage unevenly with an outer peripheral surface of the tube in an axial direction. Connection device for fittings and tubes. 3. The female screw of a nut member according to claim 2, wherein the retaining member that engages with the outer peripheral surface of the tube in the axial direction is a female screw, and a screw pitch of the female screw is screwed to a male screw of the fitting. A coupling device for connecting a fitting and a tube, wherein the coupling device and the tube are set at the same pitch. 4. The method according to claim 1, wherein
A coupling device for connecting a tube with a joint fitting, wherein the tube is a tube made of a PVC resin in which fibers for pressure resistance are embedded.