JP5415032B2 - Joint structure of resin tube - Google Patents

Description

  The present invention relates to a joint structure for a resin tube.

  In the field of semiconductor manufacturing, various chemicals such as hydrofluoric acid water and ammonia water, and ultrapure water are used for cleaning silicon wafers and the like. Tubes for supplying chemicals and the like as well as devices such as flowmeters are made of a fluororesin that can maintain high cleanliness and has excellent corrosion resistance. Therefore, a fluororesin is used for the same reason also in the joint structure which connects tubes or an apparatus and a tube.

  As shown in FIG. 11, this type of joint structure 1 </ b> S is a structure in which the enlarged diameter end portion 111 of the resin tube 100 is attached to the joint main body 120 and screwed with a cap nut 150 to be tightened. Specifically, the cylindrical portion 121 of the joint main body 120 is inserted into the enlarged diameter end portion 111 of the resin tube 100. By screwing the cap nut 150 to the joint main body 120, the inner flange portion 151 of the cap nut presses the enlarged diameter end portion 111 of the resin tube against the end portion 121 of the joint main body. Reference numeral 125 shown in the figure is an outer thread portion of the joint body, and 155 is an inner thread portion of the cap nut.

  Thereafter, in order to improve the adhesion between the resin tube and the joint body, a joint structure in which the diameter-enlarged portion of the resin tube is pressed by a pressure contact ring has been proposed (for example, see Patent Document 1). Also, a joint structure (for example, see Patent Document 2) in which an insertion groove portion into which a diameter-expanded end portion of a resin tube is inserted is formed in the joint body, and a diameter-expanded end portion of the resin tube has a locking claw. A joint structure that is pressed by a collet portion (for example, see Patent Document 3) has also been proposed.

  Currently, high-pressure and high-pressure fluid pumping such as high-temperature water and steam is increasing due to improvement of wafer cleaning efficiency and adjustment of drug solubility. For this reason, tubes and joint structures must withstand harsh use exposed to high-temperature fluids. However, although soft fluororesin such as PTFE is suitable for cutting, it has a large linear expansion coefficient, and it is exposed to heating at the time of inflow of high-temperature fluid and cooling at the time of stoppage of the inflow of the fluid. Helps deform the cap nut. Such deformation is referred to as creep.

  In general, as shown in FIG. 11, the joint body, the tube, and the cap nut are in surface contact. Therefore, when the cap nut is screwed, the tube is attracted to the cap nut by the friction between the cap nut and the tube, and rotates in the same direction. Cheap. This is called co-rotation. When twisting force is accumulated in the tube due to co-rotation, in addition to the above-mentioned influence of heat, when the supply of fluid such as chemical solution and vibration due to its stop are applied to the tube, the tube will be restored to eliminate twisting Try to return. This has been a cause of loosening of the cap nut. Furthermore, since the joint body and the cap nut are both made of resin, viscosity and elasticity are increased as compared with a metal joint structure. Accordingly, there is a problem that the fastening strength of the cap nut is inferior.

  With the joint structure disclosed in each of the above patent documents, the fastening between the cap nut and the joint body is maintained, and a certain effect is achieved in the connection between the tubes or between the device and the tube. However, since the existing screw structure is adopted, once the cap nut is loosened due to the above-mentioned creep or co-rotation, the cap nut rotation is suppressed in the middle of the screw. It was difficult. For this reason, it has not been possible to completely eliminate the problem that a gap occurs in the connection portion of the tube due to loosening of the fastening.

In this case, there is also a technique for preventing detachment of the tube by connecting resin tubes or by connecting the device and the tube by fusion. However, if the tube or equipment is to be replaced, the pipe or equipment must be destroyed each time, and the usability becomes worse. Therefore, a joint structure that is resistant to thermal deformation (creep) and vibration of the member, maintains strong fastening, and can be connected and disconnected is desired.
Japanese Patent Laid-Open No. 10-252968 JP 2001-248768 A Japanese Patent No. 3947971

  The present invention has been made in view of the foregoing points, and is resistant to thermal deformation and vibration generated in the joint body, the resin tube, and the cap nut, and maintains a strong fastening between the joint body and the tube, even if the cap nut is screwed. Provided is a resin tube joint structure in which rotation of a cap nut can be suppressed in the middle of a screw even when looseness occurs in a wear, or between resin tubes and a fluid device and a tube can be connected and detached.

That is, the invention according to claim 1 is a joint structure in which a diameter-expanded end portion of a resin tube is fitted to a joint body, and an inner thread portion of a cap nut is screwed to an outer thread portion of the joint body to be tightened. The joint body and the cap nut are both made of a fluororesin, and the outer thread portion is formed as a polygonal portion having a cross section of 5 to 13 apexes and sides, and the inner thread portion is also a cross sectional shape. Is formed as a polygonal portion having 5 to 13 apexes and sides, and the inner screw portion of the cap nut screwed to the outer screw portion of the joint body is the apex portion of the outer screw portion When rotating the cap nut, the cap nut itself is deformed so as to expand to the outside of the inner screw portion due to the elasticity of the fluororesin, and the side portion of the inner screw portion gets over the apex portion of the outer screw portion. Resin According to the joint structure of the tube.

In the invention of claim 2 , the longest distance (r2) from the center of the outer screw portion to the vertex of the polygon in the polygonal section of the outer screw portion is from the center of the outer screw portion to the side of the polygon. 2. The resin tube joint structure according to claim 1 , having a length of 1.001 to 1.07 times the shortest distance (r1).

According to a third aspect of the present invention, the joint main body includes a cylindrical portion provided with the external thread portion, an annular lip portion in which a tip of the cylindrical portion is bulged, and the resin tube inside the cylindrical portion. A connecting cylinder part into which the enlarged diameter end part is inserted and an insertion groove part which is formed inside the cylindrical part and on the outer peripheral side of the connecting cylinder part and into which the enlarged diameter end part of the resin tube is inserted are provided. The connecting tube portion is provided with a tip tapered surface portion, and an annular groove portion is formed in the connecting tube portion outer peripheral surface portion of the tip tapered surface portion or the outer periphery of the connecting tube portion, and the cap nut includes the joint. An inner flange portion that presses the diameter-expanded end portion of the resin tube against the tip tapered surface portion when screwed with the main body, and the annular lip portion when the screw body is screwed with the annular lip portion. diameter end of the resin tube by clamping the diameter end The according to the joint structure of the resin tube according to claim 1 or 2, tapered surface portion is provided inside that presses into the annular groove side.

According to a fourth aspect of the present invention, there is provided the joint structure for a resin tube according to any one of the first to third aspects, wherein the external thread portion includes both a polygonal external thread portion and a spiral external thread portion .

According to the joint structure of the resin tube according to the first aspect of the present invention, the enlarged end portion of the resin tube is fitted to the joint body, and the inner thread portion of the cap nut is screwed to the outer thread portion of the joint body. In the joint structure to be tightened, the joint body and the cap nut are both formed of fluororesin, and the external thread portion is formed as a polygonal shape portion having a cross section of 5 to 13 apexes and sides, The inner screw portion is also formed as a polygonal portion having a cross-sectional shape of 5 to 13 apexes and sides, and the inner screw portion of the cap nut screwed to the outer screw portion of the joint body is When rotating the apex portion of the outer screw portion, the cap nut itself is deformed so as to bulge outside of the inner screw portion due to the elasticity of the fluororesin, and the side portion of the inner screw portion is the outer screw portion. Raise vertex Exceeds Therefore, joint body, a resin tube, resistant to thermal deformation and vibration generated in the cap nut, to maintain a strong engagement between the joint body and the tube, even if the cap nut even when the loosening occurs in screwing the cap nut It is possible to realize a joint structure of resin tubes that can be connected and detached from each other or between a fluid device and a tube that can suppress rotation in the middle of a screw.

In addition, the resistance of the inner thread when screwing the cap nut is reduced to eliminate the difficulty of turning the cap nut, and the resistance received from the inner screw against the rotation of the cap nut when tightening occurs Can be left in moderation. Furthermore, it can cope with shape deformation such as screwing between polygonal portions, and is excellent in corrosion resistance and chemical resistance.

According to the joint structure of the resin tube according to the invention of claim 2, in the invention of claim 1 , the longest distance (r2) from the center of the outer screw portion to the vertex of the polygon of the polygonal section of the outer screw portion ) Has a length of 1.001 to 1.07 times the shortest distance (r1) from the center of the outer thread portion to the side of the polygon, so that the outer thread portion of the joint body and the inner thread of the cap nut Both the ease of screwing by the portion and the resistance when loosening occurs in tightening can be achieved at the same time.

According to the joint structure of the resin tube according to the invention of claim 3, in the invention of claim 1 or 2 , the joint body is provided with a cylindrical portion provided with the external thread portion, and a tip of the cylindrical portion is bulged. An annular lip portion, a connecting tube portion into which the diameter-expanded end portion of the resin tube is inserted inside the tube portion, and the resin formed inside the tube portion and on the outer peripheral side of the connecting tube portion And an insertion groove portion into which an enlarged diameter end portion of the tube-made tube is inserted. The connecting tube portion is provided with a tip tapered surface portion, and the connecting tube portion on the outer periphery of the tip tapered surface portion or the connecting tube portion. An annular groove is formed in the outer peripheral surface portion, and the cap nut includes an inner flange portion that presses a diameter-expanded end portion of the resin tube against the tip tapered surface portion when screwed to the joint body, and the joint At the time of screwing with the main body, the annular lip portion is Since the tapered surface portion is provided within the enlarged end portion of the resin tube is pressed into the annular groove side by pressing the enlarged end of the manufacturing tubes, when screwed cap nut, the annular groove High pressure sealing performance can be obtained by concentrating the pressure on the edge, and it is also possible to cope with deformation caused by deformation or co-rotation of the resin tube due to temperature change of the fluid.

According to the joint structure of the resin tube according to the invention of claim 4, in the invention of any one of claims 1 to 3 , the outer screw portion is composed of both a polygonal outer screw portion and a spiral outer screw portion. It is possible to have both the ease of screwing with a cap nut and the ability to prevent loosening of screw tightening.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
1 is an exploded perspective view of a joint structure according to an embodiment of the present invention, FIG. 2 is a partially enlarged view of an external thread portion of a joint body, FIG. 3 is a longitudinal sectional view of a polygonal portion, and FIG. 4 is a joint body and a bag. FIG. 5 is a cross-sectional view of the joint structure of FIG. 1, FIG. 6 is a longitudinal sectional view of the main part when the joint body and the cap nut are screwed, and FIG. FIG. 8 is a partial perspective view of another example of a joint structure, FIG. 9 is a partial sectional view of still another joint body, and FIG. 10 is another example of the joint structure according to the present invention. It is a cross-sectional schematic diagram of a form.

  In the resin tube joint structure 1A of the first embodiment shown in the exploded perspective view of FIG. 1, the enlarged diameter end portion 11 of the resin tube 10 is fitted to the joint body 20, and at the same time, the resin tube 10 is expanded. The end portion 11 is pressed against the joint body 20 side by a cap nut 50. Then, the inner threaded portion 55 of the cap nut 50 is screwed onto the outer threaded portion 25 of the joint body 20 to achieve a tightened state. The resin tube joint structure 1A of the first embodiment is used when two resin tubes 10 and 10 are connected.

  The resin tube 10 is mainly made of a flexible material such as a fluororesin having high corrosion resistance and chemical resistance. The diameter-expanded end portion 11 is, for example, the diameter of the tube end is increased using a known flare processing machine. In the illustrated joint main body 20, the external thread portion 25 is provided on the outer periphery of the cylindrical portion 21 constituting the longitudinal direction of the joint main body. In addition, an annular lip portion 31, a connecting tubular portion 32, an insertion groove portion 33, a tip tapered surface portion 34, and an annular groove portion 35 are formed in the tubular portion 21 of the joint body 20. Details of these will be described with reference to FIG. In the figure, reference numeral 51 denotes an inner collar.

As understood from the drawing as a feature of the present invention, the thread shape of the outer thread portion 25 of the joint body 20 and the inner thread portion 55 of the cap nut 50 that are screwed together is formed as a polygonal portion 23. It is. In the polygonal portion 23 , both the outer screw portion 25 and the inner screw portion 55 are polygons having cross-sectional shapes of 5 to 13 apexes. In the outer screw portion 25 and the inner screw portion 55 of the first embodiment, the screw shape is a hexagonal polygonal shape portion.

  As can be seen from the main part diagram of FIG. 2, the polygonal part 23 provided with the external thread part 25 having a hexagonal thread shape is composed of six apexes 22 and six side parts 26. The side part 26 is formed in a curved shape in which the central part 27 of the side part is expanded in an arc shape from the center of the polygonal part 23 outward (see the broken line part of the polygonal part). Also in the cap nut 50, the polygonal portion provided with the inner screw portion 55 is composed of six apexes 57 and six side portions 56. The screw shape of the inner screw portion 55 is a shape curved from the center to the outside so as to be screwed to the outer screw portion 25. Both the external screw portion and the internal screw portion shown in the figure are triangular screws (the cross section of the screw is triangular). Of course, a trapezoidal screw, a single trapezoidal screw, or a square screw can also be used. Reference numeral 29 denotes a penetrating portion through which fluid flows through the joint body.

  FIG. 3 is an example of a polygon having a cross section of a polygonal portion provided with an external thread portion of a joint body (see FIGS. 3A to 3D). As described above, these polygons are selected from pentagons (5 vertices) to 10 triangles (13 vertices). When the number of vertices was less than 5, it was excluded because the resistance at the vertices became too large to turn the cap nut. In addition, the number of vertices is 14 or more, but if the number of vertices is increased more, the cross section of the polygonal shape portion approximates to a circle. Therefore, the resistance received from the apex portion with respect to the rotation of the cap nut when the tightening which is a feature of the present invention is loosened is reduced.

Further , in the polygon of the polygonal section cross section provided with the external thread portion, the longest distance r2 from the center Ct of the external thread portion to the polygon is the multiple of the polygonal section cross section from the center Ct of the external thread portion. The length is defined to be 1.001 to 1.07 times the shortest distance r1 to the square. This is to achieve both the ease of screwing by the outer threaded portion of the joint body and the inner threaded portion of the cap nut, and the resistance when loosening occurs in tightening. The magnification of the longest distance r2 to the shortest distance r1 is determined by the polygon of the polygonal section section to be selected, the size of the joint structure, the degree of vibration and impact applied to the joint structure, the properties of the resin described later, and the like. The

  The cross-sectional view of FIG. 3A shows the hexagonal polygonal section 23 having the cross-sectional shape disclosed in FIG. The broken line shown in the figure is a hexagon as a reference. A polygon which is a cross section of the polygonal portion is composed of a vertex 22 and a side portion 26. The longest distance r2 from the center Ct of the polygonal part 23 having the external thread part 25 to the polygon of the polygonal part cross section is the distance from the center Ct to the vertex 22. The shortest distance r1 from the center Ct of the external thread portion 25 to the polygon is a distance from the center Ct to the central portion 27 that swells in an arc shape at the side portion 26.

  The cross-sectional view of FIG. 3B shows a polygonal portion 23b having a heptagonal cross-sectional shape. The polygonal portion 23b is composed of a rouleau polygon (Ruleau heptagon), and an outer screw portion 25b is provided on the outer periphery thereof. The longest distance r2 from the center Ct of the polygonal portion 23b including the external thread portion 25b to the polygon of the polygonal portion cross section is the distance from the center Ct to the vertex 22b. The shortest distance r1 from the center Ct of the external thread portion 25b to the polygon is a distance from the center Ct to the central portion 27b that swells in an arc shape at the side portion 26b. The broken line in the figure is a reference heptagon.

  The cross-sectional view of FIG. 3C shows a polygonal portion 23c having a cross-sectional shape of a hexagon. The polygonal portion 23c is also composed of a Rouleau polygon (Ruleau nine-sided polygon), and an outer screw portion 25c is provided on the outer periphery thereof. The longest distance r2 from the center Ct of the polygonal portion 23c having the external thread portion 25c to the polygon of the polygonal portion cross section is the distance from the center Ct to the vertex 22c. The shortest distance r1 from the center Ct of the external thread portion 25c to the polygon is a distance from the center Ct to the central portion 27c that swells in an arc shape at the side portion 26c. The broken line in the figure is a reference nine-sided polygon.

  The cross-sectional view of FIG. 3D shows a polygonal portion 23d having a cross-sectional dodecagon. The polygonal portion 23d is formed of a regular dodecagon having no arcuate bulge on the side portion 26d, and an outer screw portion 25d is provided on the outer periphery thereof. The longest distance r2 from the center Ct of the polygonal portion 23d having the external thread portion 25d to the polygon of the polygonal portion cross section is the distance from the center Ct to the vertex 22d. The shortest distance r1 from the center Ct of the external thread portion 25d to the polygon is a distance from the center Ct to the side portion 26d.

  As shown in the illustrated polygonal portions 23b and 23c, when a Reuleaux polygon is used, the number of vertices is an odd number of 5 to 13. Moreover, it can also be set as a regular polygon as the polygon-shaped part 23d. In any case, as long as the magnification of the longest distance r2 with respect to the shortest distance r1 is within the above-mentioned range, it is appropriate to use a Rouleau polygon, a regular polygon, or a polygon having an arc bulge.

  The state at the time of screwing in the joint structure of the first embodiment will be described with reference to the cross-sectional view of FIG. The arrows in the figure indicate the direction of screw tightening in this example. FIG. 4A shows a state in which the inner thread portion 55 of the cap nut 50 is screwed to the outer thread portion 25 of the joint body 20 partway. As illustrated, the cap nut 50 and the polygonal portions 23 of the joint body 20 are in a tightened state. Therefore, the side 56 of the cap nut and the side 26 of the joint body constituting the polygon of the polygonal section are screwed together, and the top 57 of the cap nut and the top 22 of the joint main body are also coincident with each other. There is a relationship. The minimum thickness of the cap nut 50 at this time is the length of t1.

  FIG.4 (b) is the state rotated to the direction of 30 degree screw fastening from the figure (a). Due to the rotation of the screw tightening, the apex 57 of the cap nut is located 30 ° away from the apex 22 of the joint body. At this time, the joint body 20 and the cap nut 50 are screwed together by the engagement between the outer thread portion 25 at the apex 22 portion of the joint body 20 and the inner thread portion 55 located at the center portion of the side portion 56 of the cap nut 50. ing. In particular, when the cap nut 50 rotates the apex 22 portion of the joint body 20, the cap nut 50 is deformed so as to bulge outward and gets over the apex 22 portion of the joint body 20. The two-dot chain line in the figure is the outline of the cap nut before rotation, and the cap nut is deformed by the length of t2. When the nut is further rotated by 30 °, the cap nut is in the same position as in FIG. By repeating this rotation, screwing of the cap nut proceeds, and the resin tube is crimped to the joint body.

  Usually, the thread shape is a spiral thread formed in a cylindrical portion having a circular cross section. In this case, if loosening occurs when the outer threaded portion of the joint body and the inner threaded portion of the cap nut are screwed together, there will be friction due to the screwing of both screw portions, but there will be no resistance in the middle. The nut turns and unscrews. On the other hand, since the screw shape is a polygonal shape, even if the cap nut turns once due to loose tightening at the time of screwing by the outer screw portion of the joint body and the inner screw portion of the cap nut, the cross section The apex part of the polygonal shape becomes resistance. That is, in order to pass through the apex portion of the polygonal shape, the cap nut itself must be deformed, and an excessive load is required for the loose cap nut to continue to rotate. In addition, even if the cap nut is about to rotate, it is successively subjected to resistance each time it reaches the apex portion of the polygonal shape. As a result, even if the screw tightening is loosened, the cap nut rotation is suppressed at the initial time, and the tube pressure is maintained. That is, it is possible to realize a joint structure excellent in anti-slip performance that is extremely resistant to loosening of screw tightening.

Originally, when the polygonal shaped parts are screwed together, the members are often damaged or removed after being screwed once. However, as shown in the figure, it is necessary to screw the cap nut 50 onto the joint main body 20 while overreaching. Therefore, in order to avoid breakage of the engaging portion when screwed together, it is essential that the cap nut 50 and the joint body 20 have appropriate elasticity and can be deformed. From this point, both the cap nut 50 and the joint body 20 are formed of a resin material. Especially, as in the resin tubes, corrosion resistance, is formed from a chemical resistance superior fluororesin.

  The fluororesin that is the material of the member is PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxyalkane), FEP (perfluoroethylene propene copolymer), PVDF (polyvinylidene fluoride), or the like. These fluororesins are selected in consideration of the properties of the flowing fluid, ease of processing, flexibility, stickiness, hardness, etc. of the resin.

The longitudinal cross-sectional view of FIG. 5 shows the connection state by the joint structure 1A of the resin tube of 1st Example. The structure of the tip portion of the cylindrical portion 21 in the joint body 20 of the first embodiment will be described in conjunction with FIG. 1 described above. The structure of the tip portion is an annular shape in which a cylindrical portion 21 having an external thread portion 25 is provided on the front and rear in the longitudinal direction of the joint body 20 , and the distal end of the cylindrical portion 21 is rounded and expanded (enlarged). A lip portion 31 is formed. Inside the tube portion 21, the expanded end portion 11 of the resin tube 10 is inserted, and a connecting tube portion 32 that is in close contact therewith is provided. Further, an insertion groove portion 33 into which the enlarged end portion 11 of the resin tube 10 is inserted is formed inside the tube portion 21 and on the outer peripheral side of the connecting tube portion 32. A tapered tip end surface 34 is provided at the tip of the connecting tube portion 32. Furthermore, an annular groove 35 is formed in the tip tapered surface portion 34.

The outer diameter of the connecting cylinder portion 32 is formed slightly larger than the inner diameter of the expanded end portion 11 of the resin tube 10. This enlarged diameter end portion presses spread et been to be slightly deformed when inserting the enlarged end portion of the resin tube to the connecting tube portion. Since a restoring force for returning to the original shape acts on the expanded diameter end portion of the resin tube, the adhesion force between the resin tube and the joint body (connecting cylinder portion) is increased, and the sealing performance and the pulling strength are also increased. The tip tapered surface portion 34 has an inclination corresponding to the shape of the enlarged end portion 11 of the resin tube 10 to be mounted. This inclination is to reduce the resistance when the expanded end portion of the resin tube is inserted into the connecting cylinder portion.

  Next, a tube opening 59 through which a resin tube is inserted is provided on the side opposite to the opening 58 where the internal thread 55 of the cap nut 50 is provided. An inner flange 51 is provided around the tube opening 59. A minimum diameter portion of the cap nut 50 is formed by the inner flange portion 51 (tube opening portion 59). When the cap nut 50 is screwed to the joint main body 20, the diameter-expanded end portion 11 of the resin tube 10 is pressed to the tip tapered surface portion 34 through the inner flange portion 51.

  In addition, an inner tapered surface portion 52 is formed on the inner side of the cap nut 50 with respect to the inner flange portion 51. When the cap nut 50 is screwed to the joint body 20, the inner lip portion 31 is bent inward by the inner tapered surface portion 52. At the same time, the diameter-enlarged end portion 11 of the resin tube 10 is pressed by the annular lip portion 31, and the diameter-enlarged end portion 11 is pressure-bonded to the tip tapered surface portion 34. At the same time, a part of the enlarged diameter end portion 11 bites into the annular groove portion 35.

  Subsequently, the state at the time of screwing between the cap nut 50 and the joint body 20 will be described with reference to the schematic vertical sectional views of the main part of FIGS. 6 and 7. FIG. 6A shows an initial screwed state, and the annular lip portion 31 at the tip of the tube portion 21 of the joint body 20 is separated from the inner tapered surface portion 52 of the cap nut 50. 4, the inner taper surface portion 52 of the cap nut 50 abuts on the annular lip portion 31 of the tubular portion 21 of the joint body 20 as a result of the advancement associated with the screwing of the cap nut 50 described in FIG. Therefore, as shown by the arrows in the figure, the annular lip portion 31 is deformed so as to be bent toward the resin tube.

  Further, as the cap nut 50 is screwed forward, the inner flange portion 51 of the cap nut 50 contacts the tapered portion 12 of the enlarged diameter end portion 11 of the resin tube 10 as shown in FIG. When the pressing force f1 in the forward direction, which is the cylindrical direction of the cap nut, acts on the tapered portion 12 of the enlarged diameter end portion 11, the enlarged diameter end portion 11 is brought into pressure contact with the connecting cylindrical portion 32 of the joint main body 20. At the same time, an inward pressing force f2 is generated from the annular lip portion 31 deformed toward the center side of the joint body to the tapered portion 12 of the enlarged diameter end portion 11.

  Here, the enlarged diameter end portion 11 of the resin tube 10 pressed through the annular lip portion 31 bites into the annular groove portion 35 formed in the tip tapered surface portion 34 in accordance with the pressing amount. As shown in FIG. 7, the diameter-expanded end portion 11 of the resin tube that has bitten into the annular groove 35 abuts on the edge of the annular groove 35. Since the illustrated annular groove 35 has a box-shaped cross section, the enlarged diameter end portion 11 is in line contact with the edge 35 e of the annular groove 35. Therefore, when the pressure f3 concentrates on the edge 35e of the annular groove 35 at the time of screwing, an even higher sealing performance can be obtained. As a result, it is possible to cope with twisting caused by deformation or co-rotation of the resin tube due to temperature change of the fluid to be circulated. Although not shown, as described above, a restoring force that tries to return to the original shape is also acting on the diameter-expanded end of the resin tube. In this way, by screwing only the cap nut, it is possible to obtain very high adhesion, so it is possible to reduce the number of parts necessary for forming the pipe line, and the complexity during construction is reduced. .

The partial perspective view of FIG. 8 shows a joint body 20x used in the joint structure 1B of the resin tube of the second embodiment. According to the joint main body 20x , the external thread portion 25x is formed in both the polygonal shape portion 23p of the joint main body 20x and the cylindrical shape portion 24q that is closer to the distal end side of the joint main body than the polygonal shape portion 23p. More specifically, the external screw portion 25x includes both a polygonal external screw portion 25u formed in the polygonal portion 23p and a helical external screw portion 25v formed in the cylindrical portion 24q. The portion 25v and the polygonal external screw portion 25u are formed as a continuous thread. The cap nut screwed to the joint body 20x may be a cap nut 50 in which internal threads are formed in a polygonal portion as shown in FIG. 2, or although not shown, the opening side of the cap nut is cylindrical. Immediately after that, a polygonal shape part can be used, and an internal screw part can be provided on both sides. For convenience of illustration, the cylindrical portion 21x is an example employing the tip structure of the conventional example of FIG. Of course, it is needless to say that the connecting tube portion shown in FIG. In the drawings after the second embodiment, the same reference numerals are used for the portions common to the resin tube joint structure 1A of the first embodiment.

  Unlike the joint main body 20x of the second embodiment, not all of the outer screw portions are formed in a polygonal shape portion. Therefore, at the initial stage of screwing the cap nut, the cap nut is a helical outer screw of the cylindrical portion 24q. The part 25v can be rotated without resistance. Thereafter, when the joint structure requires tightening and the cap nut reaches a portion where it is desired to avoid screw loosening, the inner screw portion of the cap nut can be screwed with the polygonal outer screw portion 25u of the polygonal portion 23p. Therefore, it is possible to have both the ease of screwing by the cap nut and the anti-slip performance resistant to the loosening of the screw tightening described above.

  9 shows a joint body 20y used in the resin tube joint structure 1C of the third embodiment. In the joint body 20y, an annular groove portion 35 is formed in the connecting cylinder portion outer peripheral surface portion 36 on the outer periphery of the connecting tube portion 32. When the enlarged end portion 11 of the resin tube 10 is inserted into the insertion groove portion 33 and the cap nut 50y is screwed to the joint body 20y, the annular lip portion 31 at the tip of the cylindrical portion 21 is formed by the inner tapered surface portion 52y. It can be folded inward. In response to this press, the annular lip portion 31 presses the enlarged diameter end portion 11 of the resin tube 10, and the enlarged diameter end portion 11 is pressed against the outer peripheral surface portion 36 of the connecting cylinder portion. A part of the enlarged diameter end portion 11 bites into the annular groove portion 35. In the case of the joint main body 20y shown in the figure, as in the case of the joint main body 20, the pressure concentrates on the edge of the annular groove when screwing, and a higher sealing performance is exhibited.

  The embodiment described above has a structure for connecting two resin tubes. Furthermore, as in the resin tube joint structure 1D shown in the longitudinal sectional view of FIG. 10, the main body passage 19 of the various fluid devices 40 including the flow meter, the on-off valve, the pressure control valve, and the like, and the resin tube 10 It can also be applied to other connections. The configuration in which the resin tube 10 is connected to the joint body 60 by the cap nut 50 is the same as that described with reference to FIGS.

  An annular lip portion 71 is formed on the cylindrical portion 61 provided on the one side in the longitudinal direction of the joint body 60 and provided with the external thread portion 65. Inside the cylindrical portion 71, the expanded end portion 11 of the resin tube 10 is inserted, and a connecting cylindrical portion 72 that is in close contact therewith is provided. Further, an insertion groove portion 73 into which the expanded end portion 11 of the resin tube 10 is inserted is formed inside the tube portion 61 and on the outer peripheral side of the connecting tube portion 72. A tapered tip surface 74 is provided at the tip of the connecting cylinder 72. Furthermore, an annular groove 75 is formed in the tip tapered surface portion 74. Reference numeral 63 denotes a polygonal portion.

  On the other side of the joint body 60, an external thread portion 66 is formed in the polygonal portion 64. The fluid device 40 is also provided with an inner screw portion 45 similar to the inner screw portion of the cap nut shown in FIG. Therefore, even if the screw main body 60 is loosened when the joint main body 60 is connected to the fluid device 40, the joint main body side is prevented from rotating at the initial time, and the joint is excellent in anti-skid performance and is resistant to screw tightening looseness. A structure is possible.

  The joint structure of the resin tube of the present invention is, for example, a resin tube in a path for supplying a fluid such as ultrapure water, hydrofluoric acid water, ammonia water, hydrogen peroxide or the like in a semiconductor manufacturing facility such as a silicon wafer. It is used for connection between each other (see FIG. 1) or connection with a fluid device such as a flow meter and an on-off valve (see FIG. 10). It is also used for analytical instruments, manufacturing instruments, etc. in the pharmaceutical field, biochemical field, and the like.

1 is an exploded perspective view of a joint structure according to an embodiment of the present invention. It is the elements on larger scale of the external thread part of a joint main part. It is sectional drawing of a polygon-shaped part. It is a cross-sectional schematic diagram at the time of screwing of a joint main body and a cap nut. It is a longitudinal cross-sectional view of the joint structure of FIG. It is a principal part longitudinal cross-sectional view at the time of screwing of a joint main body and a cap nut. It is an expanded sectional view at the time of screwing of a joint main body and a cap nut. It is a fragmentary perspective view of the joint structure of another example. It is a fragmentary sectional view of other joint body. It is a cross-sectional schematic diagram of another form of the joint structure which concerns on this invention. It is a longitudinal cross-sectional view of the conventional joint structure.

1A, 1B, 1C, 1D Resin tube joint structure 10 Resin tube 11 Expanded end portion 20, 20x, 20y, 60 Joint body 21, 21x, 61 Tube portion 22 Vertex 23 Polygonal portion 25, 25x, 65 Outside Threaded portion 26 Side portion 31, 71 Annular lip portion 32, 72 Connecting tube portion 33, 73 Insertion groove portion 34, 74 Tip tapered surface portion 35, 75 Annular groove portion 50, 50y Cap nut 51 Inner flange 52, 52y Inner tapered surface portion

Claims (4)

The enlarged diameter end (11) of the resin tube (10) is fitted into the joint body (20), and the inner thread (55) of the cap nut (50) is fitted to the outer thread (25) of the joint body (20). ) In a joint structure that is screwed onto and tightened,
The joint body and the cap nut are both made of fluororesin,
The outer screw portion is formed as a polygonal shape portion (23) having a cross-sectional shape of 5 to 13 vertices (22) and a side portion (26), and the inner screw portion also has a cross-sectional shape of 5 to 13 vertices. (57) and a polygonal portion (23) having sides (56),
When the inner threaded portion of the cap nut screwed to the outer threaded portion of the joint body rotates the apex portion of the outer threaded portion, the cap nut itself is elastically deformed by the fluororesin. A joint structure for a resin tube, wherein the side portion of the inner screw portion gets over the top portion of the outer screw portion by being deformed so as to swell outside the portion . The longest distance (r2 ) from the center of the external screw portion (Ct) to the polygonal vertex of the polygonal section of the external screw portion is the shortest distance from the center of the external screw portion to the side of the polygon ( The joint structure for a resin tube according to claim 1 , which has a length 1.001 to 1.07 times that of r1). The joint main body includes a cylindrical portion (21) provided with the external thread portion, an annular lip portion (31) in which a distal end of the cylindrical portion is bulged, and an expansion of the resin tube inside the cylindrical portion. A connecting tube portion (32) into which the diameter end portion is inserted, and an insertion groove portion (33) which is formed inside the tube portion and on the outer peripheral side of the connecting tube portion and into which the enlarged diameter end portion of the resin tube is inserted. ), And the connecting tube portion is provided with a tip tapered surface portion (34), and the connecting tube portion outer peripheral surface portion (36) on the outer periphery of the tip tapered surface portion or the connecting tube portion is provided with an annular groove portion (36). 35) is formed,
When the screw nut is screwed to the joint body, an inner collar portion (51) for pressing the diameter-expanded end portion of the resin tube against the tip tapered surface portion when the screw nut is screwed to the joint body. The inner taper surface part (52) which presses the diameter expansion end part of the resin tube to the ring groove part side by pressing the ring lip part to the diameter expansion end part of the resin tube is provided. The joint structure of the resin tube as described in 1 or 2 . The joint structure of a resin tube according to any one of claims 1 to 3 , wherein the external thread portion includes both a polygonal external thread portion (25u) and a spiral external thread portion (25v) .

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