JPH0154599B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Technical Field of the Invention The present invention relates to a resin pipe joint used, for example, in resin piping, and more specifically to a fluororesin pipe joint with excellent pull-out resistance. (B) Background of the Invention Usually, this type of resin pipe joint is made of a resin material because it has various resin properties such as chemical resistance and electrical insulation compared to metal materials. ing. By the way, regarding the joint structure, as shown in FIGS. 6 and 7, for example, the joint body 7
1, 81 and the nuts 72, 82, the locking protrusions 73, 83 on the main body side or the nut side
By biting into the outer circumferential surfaces of the tubes 74, 84, the tubes are deformed, and the deformation resistance force becomes a pull-out resistance force. However, as is well known, resin materials have low friction characteristics, so if the joint member is made entirely of resin material, the biting and locking force will be weak from the viewpoint of the material, and therefore the pull-out resistance of the joint portion will be reduced. Due to its poor reliability, it could not be used for joints that require high durability or for important piping joints. Particularly, when the resin tube has high strength and thick wall, the tube is difficult to deform and there is a problem that the pull-out resistance is reduced. (c) Purpose of the Invention Therefore, the object of the present invention is to provide a resin pipe joint that allows for tube deformation suitable for pull-out resistance and enables a high-strength connection. (d) Summary of the Invention The present invention is a resin pipe joint that connects a fluororesin tube with a fluororesin sleeve interposed between the fluororesin joint body and a nut. The tube passes through the tube insertion hole of the nut, and one end is locked to the tube locking surface of the joint body, and in this locked state, the outer circumferential surface of the tube corresponding to the small diameter biting part of the nut and the sleeve At least on the outer circumferential surface of the tube, which corresponds slightly inwardly to the inner end of the biting part, a circumferential groove is carved to prevent the tube from slipping out in order to allow for diameter reduction deformation of the tube. , the resin pipe joint is characterized in that the depth of the groove is approximately equal to the height of the biting portion at the inner end of the sleeve. (E) Effects of the Invention According to the present invention, by screwing the nut onto the joint body, the outer peripheral tapered surface of the sleeve pressed by the nut is pressed against the inner peripheral tapered surface of the joint body. The sleeve is compressed in the axial direction over its entire length, and this tightening force in the diametrical direction presses and compresses the tube in contact with the inner peripheral surface of the sleeve, causing concentrated stress to act on the circumferential groove of the tube.
Starting from the thin-walled part of the tube, the tube is deformed into a stepped state with a locally reduced diameter, and the biting part of the inner end of the sleeve comes into contact with this local step, which reduces the shearing force in the axial direction. This action ensures that the tube is prevented from coming off. Therefore, even if all of these joint constituent members are made of resin, a highly reliable resin pipe joint that has high pull-out resistance and can be firmly connected can be obtained. (F) Embodiment of the Invention An embodiment of the invention will be described in detail below based on the drawings. The drawings show a resin pipe joint, and in FIGS. 1 to 4, this resin pipe joint 11 has a joint body 12.
, Nut 13, Tube 14, and Sleeve 1
5, all of which are molded from resin material. The above-mentioned resin materials are inexpensive resin materials with low shrinkage that provide various properties such as chemical resistance, electrical insulation, high strength, high hardness, and high molding accuracy, such as tetrafluoroethylene to ethylene copolymer resins. (ETFE),
Fluororesins such as perfluoro-alkoxy resin (PFA) and trifluorochloroethylene-ethylene copolymer resin (ECTFE) are suitable. The above-mentioned joint body 12 has a male thread 1 on the outer peripheral surface of the tube end.
6, and a concave tube locking surface 1 in the center of the end surface for inserting and locking the end of the tube 14.
7 is formed, and an inner circumferential tapered surface 18 that becomes smaller in diameter toward this locking surface 17 is formed on the peripheral surface of this locking surface 17. The above-mentioned nut 13 has a wall surface on one end surface of a cylindrical shape having a hexagonal outer circumferential surface, and has a female thread 19 carved on the inner circumferential surface of the open end side to be screwed into the male thread 16 of the above-mentioned joint body 12. A tube insertion hole 20 is provided in the center of the wall on the outer end side, the inner peripheral surface of this insertion hole 20 is provided as a biting tapered surface 21, and the inner side of this biting tapered surface 21 is provided as a tube insertion hole 20. It is provided in a small-diameter biting part 21a which is set to have a smaller diameter than the outer diameter of 14 and also serves as a locking part. In addition, Natsuto 1
3 is provided with a locking step 22 for holding a sleeve to be described later. The sleeve 15 described above has a cylindrical shape, and its inner peripheral surface is large enough to fit over the tube 14.
The inner end side of the outer peripheral surface is the inner peripheral tapered surface 1 of the joint body 12
8 is formed with an outer circumferential tapered surface 23 facing the circumferential surface at the same angle, and the inner end side is further cut off vertically, and the inner circumferential surface side of the inner end is set as a biting part 24 which also serves as a locking part for the tube 14. In addition, there is a gap 25 provided by relatively large chamfering on the outer end side of the inner circumferential surface.
is formed. The outer end of the sleeve 15 is locked to the locking step 22 of the nut 13 described above. Note that the inner end surface of this sleeve 15, the inner circumferential tapered surface 18 of the joint body, and the tube 14 described later
A space surrounded by the circumferential groove on the outer circumferential surface is provided as a gap 26 on the inner end side of the sleeve. The tube 14 described above passes through the tube insertion hole 20 of the nut 13 and has one end locked on the tube locking surface 17 of the joint body 12. A circumferential groove 28 is carved on the outer circumferential surface, and a circumferential groove 28 is further set on the outer circumferential surface of the tube corresponding to a slightly inner side of the inner end of the biting portion 24 of the sleeve 15 for locking to prevent the tube 14 from slipping out in order to allow diameter reduction deformation. A circumferential groove 27 is carved therein. Note that the circumferential groove 27 is formed in a tapered shape having a small diameter corresponding to the direction in which the sleeve 15 bites. First of all, the resin pipe joint configured in this way is
One end of the tube 14 is inserted into the sleeve insertion hole 20 of the nut, and then the sleeve 15 is fitted onto the insertion portion, and the nut 13 is screwed onto the joint body 12. By this screwing operation, the sleeve 15 is compressed from the pre-tightening state shown in FIG. 3 in the axial direction to be connected, as shown in FIG. Due to the mutual taper contact action, the entire length of the biting portion 24 of the sleeve 15 is compressed in the axial direction, and the diameter is reduced over the entire length, and the sleeve 15 is retained in the circumferential groove 27 of the tube 14. Bits in and firmly fixes the tube 14 to prevent it from coming out. In this case, the circumferential grooves 27 and 28 correspond to the inner and outer ends of the sleeve 15, and due to the thinning of the tube 14 due to the circumferential grooves 27 and 28, the sleeve 15 is subjected to the tightening force of diameter reduction deformation. Concentrated stress acts on the thin-walled portions on both sides, and the diameter of the thin-walled portions on both sides is locally reduced together with the sleeve 15 into a stepped state with a smaller diameter, and due to the contact between the stepped portions and the inner end of the biting portion 24, The shearing force in the axial direction can reliably prevent it from coming off. Further, due to the biting action of the sleeve 15 on the tube 14, a slight bulge phenomenon occurs on the outer circumferential surface of the tube 14.
Since the bulging portions intervene at 6 and 25, there is no stress on the biting ability. Furthermore, during use, the pressure of the fluid flowing within the tube 14, the fluid temperature (high temperature), etc. are applied to promote the biting property, so that the resistance to removal is further improved. As shown in FIG.
A corresponding circumferential groove 52 may be formed only on one side to provide anti-slip properties; in this case, the circumferential groove 5
The step portion 27 formed by 2 provides an anti-removal action. Next, Table 1 shows the experimental results of the joint strength of the inventive example and the conventional example of the above-mentioned resin pipe joint.

[Table] In Table 1, T indicates the value when the tube separates from the joint, and B indicates the value when the tube ruptures. As a result, it was found that in the conventional example, the pressure resistance was removed before the tube ruptured, whereas in the present invention, the tube was firmly connected until it ruptured. Furthermore, in terms of pull-out resistance, the value of this invention example was sufficiently high, and it was recognized that the pull-out resistance was excellent.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is an exploded perspective view showing a resin pipe joint, FIG. 2 is a longitudinal cross-sectional view showing the connected state of the resin pipe joint, and FIG. 3 is a view of the resin pipe joint before connection. FIG. 4 is an enlarged longitudinal cross-sectional view of the main part showing the state after connection; FIG. 5 is a longitudinal cross-sectional view of the resin pipe joint showing another embodiment of the present invention; FIGS. 6 and 7 are longitudinal cross-sectional views showing the connected state of a conventional resin pipe joint. 11... Resin pipe fitting, 12... Fitting body, 13...
Nut, 14...Tube, 15, 51...Sleeve, 16...Male thread, 17...Tube locking surface, 18
... Inner circumference tapered surface, 19 ... Female thread, 20 ... Tube insertion hole, 21 ... Biting taper surface, 21a ... Small diameter biting part, 22 ... Locking step part, 23 ... Outer circumference tapered surface,
24... Biting portion, 27, 28, 52... Circumferential groove.

Claims (1)

[Claims] 1. A joint body made of fluororesin having a male thread on the outer peripheral surface of the tube end, a tube locking surface with a recess formed on the end surface, and an inner circumferential tapered surface formed on the inner peripheral surface thereof; , having a female thread on the inner peripheral surface that screws into the male thread,
The tube insertion hole at the center of the outer end surface has a fluororesin nut with a biting tapered surface that has a small-diameter biting part on the inside that has a smaller diameter than the tube's outer diameter, and there is a nut between the fitting body and the nut. a fluororesin sleeve having an inner circumferential surface formed with a biting part for the outer circumferential surface of the tube and an outer circumferential tapered surface opposing the inner circumferential tapered surface of the joint body; One end passes through the hole and is locked to the tube locking surface, and in the locked state, an outer circumferential surface corresponding to the small-diameter biting part of the nut, and an outer periphery slightly inward from the inner end of the biting part of the sleeve. At least on the outer circumferential surface of the latter, a circumferential groove is carved to prevent the tube from slipping out, and the depth of the circumferential groove is equal to the height of the biting part at the inner end of the sleeve. 1. A resin pipe joint comprising a fluororesin tube having approximately equal flexibility.