JP6711732B2 - Resin pipe fitting - Google Patents

Description

The present invention relates to a resin pipe joint.

BACKGROUND ART Conventionally, there is known a resin pipe joint that can be used in a manufacturing apparatus in technical fields such as semiconductor manufacturing, medical/pharmaceutical manufacturing, food processing, and chemical industry (see, for example, Patent Document 1). This type of resin pipe joint is for connecting a tube for circulating a fluid such as ultrapure water or a chemical solution to another tube or a fluid device, and is configured to be joined to the tube.

The resin pipe joint includes a joint body, an inner ring, and a union nut for joining with the tube. The inner ring and one longitudinal end portion of the tube into which the inner ring is press-fitted are connected to the joint body. The union nut holds the one longitudinal end of the tube so that the one longitudinal end of the tube is not pulled out from the joint body.

The resin pipe joint is often subjected to a thermal cycle (specific example: normal temperature (about 25° C.)→high temperature (about 200° C.)→normal temperature) during use. If an unexpected drawing force is applied to the tube joined to the resin pipe joint after heat cycle loading, the tube may be pulled out from the joint body so as to be separated from the resin pipe joint. was there. Therefore, it has been desired to improve the withdrawal resistance of the tube in the resin pipe joint.

JP, 10-054489, A

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a resin pipe joint that can improve the withdrawal resistance of one end of the joined tubes in the longitudinal direction.

The present invention is
In a resin pipe joint that can be joined to the tube in a state where one end in the longitudinal direction of the tube is inserted inside,
A joint body having a tubular portion into which one end in the longitudinal direction of the tube can be inserted,
A press-fitting portion that can be press-fitted into one side of the tube in the longitudinal direction, the press-fitting portion that can be inserted into the tubular portion together with the one end in the longitudinal direction of the tube in a state of being press-fitted to the one side of the longitudinal direction of the tube. With an inner ring,
In order to connect the one end side in the longitudinal direction of the tube to the joint body, in a state where the press-fitting part is inserted into the tubular part together with the one end part in the longitudinal direction of the tube, the press-fitting part is radially interposed between the press-fitting part and the press-fitting part. A union nut having a connecting portion that can be screwed to the outer peripheral portion of the joint body so as to sandwich one end portion in the longitudinal direction of the tube,
The inner ring and the union nut are made of resin materials different from each other, and each has a property of contracting with a change in ambient temperature,
The shrinkage rate in the radial direction at the connecting portion of the union nut is set to be 0.05% or more higher than the shrinkage rate in the radial direction at the press-fitting portion of the inner ring.

According to this configuration, in a state where the tube is joined to the resin pipe joint, when the inner ring and the union nut are heated by heat transfer from a fluid or the like and then cooled (heat cycle is applied. In this case, the connecting portion of the union nut can be largely contracted in the radial direction as compared with the press-fitting portion of the inner ring.

Therefore, when the resin pipe joint is joined to the tube, the reduction amount of the inner diameter of the connecting portion of the union nut is larger than the reduction amount of the outer diameter of the press-fitting portion of the inner ring. The force that holds the tube supported from the inside in the radial direction by the portion from the outside in the radial direction can be increased by the connecting portion that is overlapped in the radial direction via the tubular portion of the joint body.

Therefore, when a pulling force is applied to the tube so as to pull out the tube from the resin pipe joint, the tubular portion of the joint body and the tube that are pushed radially inward by the connecting portion of the union nut. It is possible to increase the frictional force generated during. As a result, the withdrawal resistance of the tube in the resin pipe joint can be improved.

According to another aspect of the invention,
The union nut is
In the state where the press-fitting portion is inserted into the tubular portion together with the longitudinal end portion of the tube, as the connecting portion is screwed with respect to the outer peripheral portion of the tubular portion, the longitudinal end portion of the tube A pressing part that can press the part side from the outside in the radial direction toward the press-fitting part,
The radial contraction rate of the pressing portion of the union nut is set to be larger than the radial contraction rate of the press-fitting portion of the inner ring.

According to this configuration, when the inner ring and the union nut are cooled after being heated by heat transfer from a fluid or the like, the pressing part of the union nut is pressed into the inner ring like the connecting part. It is possible to make the contraction in the radial direction larger than that of the portion.

Therefore, when the resin pipe joint is joined to the tube, the reduction amount of the inner diameter of the pressing portion of the union nut becomes larger than the reduction amount of the outer diameter of the press-fitting portion of the inner ring. It is possible to increase the force that holds the one end portion side in the longitudinal direction of the tube supported from the radially inner side by the portion from the radially outer side by the pressing portion that is overlapped in the radial direction.

Therefore, in order to pull out the tube from the resin pipe joint, when a pulling force is applied to the tube, a frictional force generated between the pressing portion of the union nut and the tube outside the joint body. Can be raised. As a result, the pull-out resistance of the tube in the resin pipe joint can be further improved.

ADVANTAGE OF THE INVENTION According to this invention, the resin-made pipe joint which can improve the pull-out-proof performance of the longitudinal direction one end part of the joined tube can be provided.

It is sectional drawing which shows the joint structure of the resin-made pipe joint which concerns on one Embodiment of this invention, and the longitudinal direction one end part of a tube. It is a figure which shows the inner ring in each of Example 1 and Example 2 of this invention, and some dimension of a union nut. It is a figure which shows the inner ring in each of the comparative example 1, the comparative example 2, and the comparative example 3, and some dimension of a union nut. It is a figure which shows the shrinkage rate of the inner ring and union nut in each of Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3 based on the description of FIG. 2 or FIG. 3. It is a figure which shows the pull-out resistant performance of the tube in each of Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3.

An embodiment of the present invention will be described with reference to the drawings.

The resin pipe joint 1 according to one embodiment of the present invention can be used in a semiconductor, liquid crystal, or organic EL manufacturing apparatus or the like. When the resin pipe fitting 1 is used in the manufacturing apparatus or the like, the tube 2 is connected to another tube (not shown) or a fluid device such as a valve or a pump, as shown in FIG. It can be joined with.

The resin pipe joint 1 can be joined to the tube 2 with the longitudinal one end 5 of the tube 2 inserted into the resin pipe joint 1, and includes a joint body 11 and an inner ring 12. And a union nut 13. In the present embodiment, the tube 2 is a flexible cylinder having a substantially constant inner diameter, and is made of a resin material such as a fluororesin material.

In the following description, one side in the axial direction refers to the tube 2 side in the resin pipe joint 1 in FIG. 1, and the other side in the axial direction refers to the joint body 11 side in the resin pipe joint 1 in FIG. Point to.

The joint body 11 has a tubular portion (an outer tubular portion 22 described later) into which the longitudinal one end 5 of the tube 2 can be inserted. The joint body 11 also has a fluid passage 16. The fluid flow path 16 communicates with the fluid flow path 7 of the tube 2 when the longitudinal one end portion 5 of the tube 2 is inserted into the outer tubular portion 22 (the receiving portion 15 thereof). It is provided inside the joint body 11.

The joint body 11 is made of a predetermined resin material. Preferably, the joint body 11 is made of a fluororesin material as in the present embodiment. Specific examples of the fluororesin material include PFA (perfluoroalkoxy fluororesin), PTFE (polytetrafluoroethylene), and ETFE (ethylene/tetrafluoroethylene copolymer).

In the present embodiment, the joint main body 11 includes a main body tubular portion 21, the outer tubular portion 22, and an inner tubular portion 23. The main body tubular portion 21 has a cylindrical portion, and has a first fluid passage 24 that can communicate with the fluid passage 7 of the tube 2. The first fluid passage 24 has a substantially circular cross section, and is provided inside the main body tubular portion 21 along the axial direction so as to form a part of the fluid passage 16.

The outer tubular portion 22 has a threaded portion that can be threadedly engaged with the union nut 13, and one end in the axial direction of the main tubular portion 21 is formed so as to form the receiving portion 15. Is coaxially projected. The outer cylindrical portion 22 is formed in a cylindrical shape and has the receiving portion 15 therein. The screwed portion is provided as a male screw portion 25 on the outer peripheral portion of the outer tubular portion 22 along the axial direction.

The inner tubular portion 23 is arranged radially inward of the outer tubular portion 22. The inner tubular portion 23 has a projecting end portion 26, and the projecting end portion 26 is located closer to the main body tubular portion 21 than the projecting end portion 27 provided in the outer tubular portion 22 is. The main body tubular portion 21 is coaxially projected from one axial end of the main tubular portion 21 in the same direction as the outer tubular portion 22 (one axial direction of the main tubular portion 21).

The inner tubular portion 23 has an inner diameter substantially the same as the inner diameter of the main body tubular portion 21, and is formed in a cylindrical shape having an outer diameter smaller than the inner diameter of the outer tubular portion 22. It has a second fluid passage 28 that can communicate with the fluid passage 7. The second fluid channel 28 has a substantially circular cross section, and is coaxially connected to the first fluid channel 24 so as to form the fluid channel 16 together with the first fluid channel 24. Has been done.

The joint main body 11 further includes a groove portion 29 formed so as to be open in one axial direction and surrounded by the main body tubular portion 21, the outer tubular portion 22, and the inner tubular portion 23. The groove portion 29 is formed in an annular shape extending along the entire circumference of the outer peripheral surface of the inner cylindrical portion 23 so that the other end portion in the axial direction of the inner ring 12 (insertion portion 36 described later) can be press-fitted. ing.

Further, the inner ring 12 has a press-fitting portion 31 which can be press-fitted to the one end 5 side in the longitudinal direction of the tube 2. The press-fitting portion 31 is pressed into the longitudinal end portion 5 side of the tube 2 from the opening portion 8 thereof, and together with the longitudinal end portion 5 of the tube 2, the receiving portion 15 of the outer tubular portion 22 (the aforementioned It is configured so that it can be inserted into the joint body 11).

In the present embodiment, the inner ring 12 has, in addition to the press-fitting portion 31, an insertion portion 32 that can be inserted into the receiving portion 15 of the joint body 11. The insertion portion 32 includes a fitting portion 35, the insertion portion 36, and a contact portion 37. The inner ring 12 also has a fluid passage 38 that allows the fluid passage 7 of the tube 2 and the fluid passage 16 of the joint body 11 to communicate with each other.

Specifically, the press-fitting portion 31 has the same outer peripheral shape (cylindrical shape) as the inner peripheral shape of the longitudinal one end 5 of the tube 2 (a portion of which the diameter is increased by press-fitting the press-fitting portion 31). And is arranged on one axial side of the inner ring 12. The press-fitting portion 31 has an inner diameter that is substantially the same as the inner diameter of the tube 2 (the inner diameter in the unexpanded state, the same applies below), and the axial one side portion of the fluid flow path 38. Is provided inside. Here, the fluid channel 38 has a substantially circular cross section.

The press-fitting portion 31 also has an outer diameter that is larger than the inner diameter of the tube 2, and the inner diameter of the longitudinal end portion 5 side of the tube 2 is increased so that the longitudinal end portion 5 side of the tube 2 is expanded. While press-contacting the entire circumference, the tube 2 is press-fitted into the longitudinal end portion 5 side of the tube 2 from the opening portion 8 and can be held at a predetermined press-fitting position with respect to the longitudinal end portion of the tube 2. It is configured.

Then, the press-fitting portion 31 has one end portion in the longitudinal direction of the tube 2 so that the press-fitting position with respect to the one end portion in the longitudinal direction of the tube 2 does not change in a state where the press-fitting portion 31 is press-fitted to the one end portion 5 side in the longitudinal direction of the tube 2. 5 and 5 can be inserted into the receiving portion 15 (inside the joint body 11) of the outer tubular portion 22 from the other axial side of the press-fitting portion 31.

When the press-fitting portion 31 is inserted into the receiving portion 15 of the outer tubular portion 22, the longitudinal one end portion 5 of the tube 2 is sandwiched between the press-fitting portion 31 and the outer tubular portion 22. That is, the press-fitting portion 31 is in pressure contact with the longitudinal end portion 5 of the tube 2 from the radially inner side over the entire circumference and the entire axial length, and the outer tubular portion 22 is fully attached to the longitudinal end portion 5 of the tube 2. It contacts from the outer side in the radial direction over the entire length in the circumferential and axial directions.

The press-fitting portion 31 further has a bulging portion 39. When the press-fitting part 31 is press-fitted to the longitudinal one end 5 side of the tube 2, the bulging part 39 improves the sealing performance between the two and prevents the tube 2 from coming off. It is an annular convex portion for illustration and is formed so as to bulge outward in the radial direction of the inner ring 12 on one axial side of the press-fitting portion 31.

The bulging portion 39 includes a tapered first outer peripheral surface and a second outer peripheral surface which are arranged so as to face one and the other in the axial direction with the top portion (the outermost end portion in the radial direction) interposed therebetween. It has a convex cross section. The second outer peripheral surface of the bulging portion 39 is such that when the press-fitting portion 31 is inserted into the outer tubular portion 22, one axial end portion of the longitudinal one end portion 5 of the tube 2 serves as the outer tubular portion 22. It can be sandwiched between.

The insertion section 32 is arranged outside the tube 2 when the press-fitting section 31 is press-fitted to the longitudinal one end 5 side of the tube 2. The insertion portion 32 has a tubular shape and is arranged on the other axial side of the inner ring 12. The insertion portion 32 has an inner diameter that is substantially the same as the inner diameter of the press-fitting portion 31, and is provided so as to include the portion on the other axial side of the fluid flow passage 38 therein.

The insertion portion 32 has an outer diameter that is substantially larger than the outer diameter of the press-fitting portion 31, and the press-fitting portion 31 is inserted into the receiving portion 15 of the outer tubular portion 22 together with the longitudinal one end portion 5 of the tube 2. At this time, the outer tubular portion 22 is inserted into the receiving portion 15 of the outer tubular portion 22 prior to the press-fitting portion 31 so as to come into contact with the outer tubular portion 22 from the radially inner side over the entire circumference and the entire axial length. Has been done.

In the insertion portion 32, the fitting portion 35 has a tubular shape and is coaxially connected to the axially other end portion of the press-fitting portion 31. The fitting portion 35 is formed in a cylindrical shape having an inner diameter substantially the same as each of the inner diameter of the press-fitting portion 31 and the inner diameter of the tube 2, and is a part of a portion on the other axial side of the fluid passage 38. Has a fluid flow path.

The fitting portion 35 has an outer diameter larger than the outer diameter of the press-fitting portion 31 (excluding the vicinity of the top of the bulging portion 39), and the insertion portion 32 has the receiving portion 15 of the outer tubular portion 22. When it is inserted into the outer cylindrical portion 22, the outer cylindrical portion 22 is brought close to, abutted on, or pressed against the outer cylindrical portion 22 from the inside in the radial direction. Here, the fitting portion 35 is configured to come close to, abut on, or come into pressure contact with the outer tubular portion 22 over the entire circumference and the entire axial length thereof.

The insertion portion 36 is a tubular member that can be press-fitted into the groove portion 29 of the joint body 11, and is coaxially projected from the fitting portion 35 in the other axial direction. The insertion portion 36 has a cylindrical shape having an inner diameter slightly smaller than the outer diameter of the inner cylindrical portion 23 of the joint body 11 and an outer diameter substantially the same as or slightly larger than the fitting portion 35. Has been formed.

The insertion portion 36 is press-fitted into the groove portion 29 when the insertion portion 32 is inserted into the receiving portion 15 of the outer tubular portion 22, and the first sealing region 41 is formed between the insertion portion 36 and the inner tubular portion 23. In order to form the above, the inner cylindrical portion 23 is pressed from the outside in the radial direction. Here, the insertion portion 36 is configured to come into contact with the inner cylindrical portion 23 over the entire circumference and the entire length in the axial direction.

At this time, the insertion portion 36 is configured to come into contact with or come into pressure contact with the outer tubular portion 22 from the radially inner side. In this case as well, the insertion portion 36 is in contact with the outer tubular portion 22 over the entire circumference and the entire axial length thereof.

The contact portion 37 has a tubular shape and is arranged radially inward of the insertion portion 36. The contact portion 37 is arranged such that the protruding end portion 43 of the contact portion 37 is located closer to the fitting portion 35 side than the protruding end portion 44 of the insertion portion 36 in the axial direction of the inner ring 12. The fitting portion 35 is coaxially projected in the same direction as the insertion portion 36 (the other axial direction of the fitting portion 35).

The contact portion 37 is formed in a cylindrical shape having an inner diameter substantially the same as the inner diameter of the fitting portion 35 and each inner diameter of the inner tubular portion 23 of the joint body 11. The contact portion 37 is smaller than the inner diameter of the insertion portion 36 so that the protruding end portion 26 side of the inner tubular portion 23 can be sandwiched between the contact portion 37 and the one axial side portion of the insertion portion 36. Has an outer diameter.

When the insertion portion 36 is press-fitted into the groove portion 29, the contact portion 37 restricts the deformation movement of the inner cylinder portion 23 inward in the radial direction due to the press-fitting, and the inner cylinder portion 23. In order to form a second seal area 42 between the inner cylinder portion 23 and the inner cylinder portion 23, the inner cylinder portion 23 is pressed from one side in the axial direction. Here, the contact portion 37 is configured to come into contact with the inner cylindrical portion 23 over the entire circumference thereof.

Further, the union nut 13 has a connecting portion 46. In the connecting portion 46, the press-fitting portion 31 is inserted into the receiving portion 15 together with the longitudinal end portion 5 of the tube 2 so as to connect the longitudinal end portion 5 side of the tube 2 to the joint body 11. In this state, it is configured so that it can be screwed onto the outer peripheral portion of the joint body 11 so that the longitudinal one end 5 of the tube 2 is sandwiched between the tube 2 and the press-fitting portion 31 in the radial direction.

In this embodiment, the union nut 13 includes a pressing portion 47 in addition to the connecting portion 46. The union nut 13 also has a through hole that allows the tube 2 to pass therethrough in its shaft portion so that the union nut 13 can move relative to the tube 2 in the longitudinal direction with the tube 2 passing through the through hole. In addition, the tube 2 can be loosely fitted.

The connecting portion 46 includes a portion of the through hole and a screwing portion that can be screwed into the screwing portion (the male screw portion 25) of the outer tubular portion 22 of the joint body 11. The connecting portion 46 has a tubular shape and is arranged on the other axial side of the union nut 13. The threaded portion of the connecting portion 46 is provided as an internal thread portion 49 along the axial direction on the inner peripheral portion of the connecting portion 46 so as to correspond to the threaded portion of the outer tubular portion 22 of the joint body 11. ing.

When the female threaded portion 49 is screwed into the male threaded portion 25 of the outer tubular portion 22 of the joint body 11 and then is screwed in the other axial direction, the connecting portion 46 causes the outer tubular portion 22 to have a diameter equal to that of the outer tubular portion 22. The longitudinal direction one end part 5 of the tube 2 inserted together with the outer cylinder part 22 and the press-fitting part 31 of the inner ring 12 is sandwiched between the outer cylinder part 22 and the press-fitting part 31.

At this time, the connecting portion 46 makes contact with the outer tubular portion 22 over the entire circumference of a screwing region where the female screw portion 49 is screwed into the male screw portion 25 of the outer tubular portion 22 from the outside in the radial direction. The tube 2 is indirectly contacted with the longitudinal one end portion 5 of the tube 2 inserted in the receiving portion 15 of the tubular portion 22 through the outer tubular portion 22 over the entire circumference of the screwing region.

The pressing portion 47 has the connecting portion 46 with respect to the male screw portion 25 in the outer tubular portion 22 in a state where the press-fitting portion 31 is inserted into the receiving portion 15 together with the longitudinal one end portion 5 of the tube 2. As the tube 2 is screwed, the one end 5 side in the longitudinal direction of the tube 2 is pressed toward the joint body 11 from one side in the axial direction thereof, and is directed toward the press-fitting portion 31 from the outside in the radial direction. It is configured so that it can be pressed.

The pressing portion 47 has a tubular shape and is arranged on one axial side of the union nut 13. The pressing portion 47 is coaxially connected to the connecting portion 46 such that the inner peripheral portion thereof is located radially inward of the inner peripheral portion of the connecting portion 46.
The pressing portion 47 has an inner diameter smaller than the inner diameter of the connecting portion 46 and slightly larger than the outer diameter of the tube 2, and includes the remaining portion of the through hole.

The pressing portion 47 sandwiches the longitudinal one end portion 5 of the tube 2 in which the connecting portion 46 is inserted together with the outer tubular portion 22 and the press-fitting portion 31 of the inner ring 12 with the press-fitting portion 31. At this time, it is arranged outside the outer tubular portion 22 on one side in the axial direction, and the one end 5 side in the longitudinal direction of the tube 2 can be sandwiched between the press-fitting portion 31.

Specifically, the pressing portion 47 has a corner portion 48 provided on the other axial side of the inner peripheral portion thereof, and the connecting portion 46 is screwed with respect to the male screw portion 25 of the outer tubular portion 22. At this time, the one end 5 side in the longitudinal direction of the tube 2 is pressed from the one axial side toward the joint body 11 by the corner portion 48, and the press-fitting portion is pressed by the corner portion 48 from the radially outer side. It can be pressed (31), in other words, can be held (sandwiched) by being sandwiched between it and the press-fitting portion 31.

Here, in the corner portion 48, the connecting portion 46 is screwed with respect to the male screw portion 25 of the outer cylinder portion 22, that is, the tightening of the union nut 13 with respect to the joint body 11 is advanced. Is moved in the axial direction by pressing the expanded diameter portion of the tube 2 so as to drive the wedge into the expanded diameter portion (the portion along the first outer peripheral surface) of the tube 2 by the bulging portion 39. ..

When the tube 2 is joined to the resin pipe joint 1 thus configured, for example, first, the union nut 13 is loosely fitted to the tube 2. Next, in order to connect the inner ring 12 to the tube 2, the press-fitting portion 31 is inserted from the opening portion 8 into one end portion 5 in the longitudinal direction of the inner ring 12 while the diameter of the tube 2 is expanded by the bulging portion 39 and is coaxial. Press fit.

Then, the insertion portion 32 of the inner ring 12 outside the tube 2 is inserted into the receiving portion 15 (inside the resin pipe joint 1) of the outer tubular portion 22, and then the press-fitting portion 31 and this are inserted. The one end portion 5 in the longitudinal direction of the tube into which is pressed is inserted. Finally, the connecting portion 46 of the union nut 13 is screwed into the male screw portion 25 of the outer cylinder portion 22 and is screwed toward the joint body 11 to a predetermined position.

At the time of this screwing, in this embodiment, the insertion portion 36 can be press-fitted into the groove portion 29 so that the first sealing region 41 in which the sealing force acts in the radial direction is formed, and the sealing is performed. The union nut 13 is tightened so that the contact portion 37 can be pressed into contact with the inner cylindrical portion 23 so that the second seal region 42 in which a force acts in the axial direction is formed.

In addition, in the resin pipe joint 1, the inner ring 12 and the union nut 13 are made of different resin materials, and each has a property of shrinking with a change in ambient temperature. . Further, the radial contraction rate of the connecting portion 46 of the union nut 13 is set to be 0.05% or more larger than the radial contraction rate of the press-fitting portion 31 of the inner ring 12. That is, the union nut 13 is made of a resin material having a greater shrinkage rate after molding than the resin material used for the inner ring 12.

Here, different resin materials include not only different resin names but also different resin grades even though the resin names are the same. That is, different resin grades may have different MFR (melt flowability) during molding and flex life (flex resistance) after molding due to differences in molecular structure, molecular weight, crystallinity, etc. However, the shrinkage rate of the molded product may differ. Therefore, by using resin materials of different resin grades between the inner ring 12 and the union nut 13, a significant difference (difference of 0.05% or more) is caused in the shrinkage rate of both. May be possible.

The inner ring 12 and the union nut 13 are each made of a predetermined resin material. Preferably, the inner ring 12 and the union nut 13 are each made of a fluororesin material as in the present embodiment. Specific examples of the fluororesin material include PFA, PTFE, and ETFE.

The inner ring 12 is heated when the atmospheric temperature (including the temperature of the fluid flowing inside the resin pipe fitting 1) rises by a predetermined value from around normal temperature (about 25° C.), and from that state, the atmospheric temperature is the normal temperature. It is cooled by descending to the vicinity, and when such temperature fluctuation occurs for the first time, the press-fitting portion 31 can be contracted in the radial direction as compared with the initial state.

The union nut 13 is heated when the ambient temperature (including the temperature of the fluid flowing inside the resin pipe fitting 1) rises by a predetermined value from around room temperature, and the ambient temperature drops from that state to around room temperature. When the temperature fluctuation occurs for the first time, the connecting portion 46 can be contracted in the radial direction as compared with the initial state.

More specifically, the inner ring 12 and the union nut 13, including the press-fitting portion 31 and the connecting portion 46, respectively, are not heated before heating (when a predetermined amount of heat is applied due to a change in ambient temperature). Compared with the above, it expands, and when it is cooled thereafter (when heat is taken away due to the change in the ambient temperature), it contracts more than initially (before the first application of heat).

When contracting, the connecting portion 46 of the union nut 13 is set so as to contract more radially than the press-fitting portion 31 of the inner ring 12.

As described above, the inner ring 12 and the union nut 13 are made of different resin materials, so that the shrinkage rate in the radial direction of the press-fitting portion 31 of the inner ring 12 and the connecting portion 46 of the union nut 13 are different. Although a difference in a predetermined range can be provided between the shrinkage ratio in the radial direction and the shrinkage ratio in the radial direction, the difference in shrinkage ratio between the two may be further increased by the presence/absence of heat treatment or adjustment of molding conditions. Specifically, heat treatment is applied only to the inner ring 12 so that the shrinkage rate after temperature change becomes substantially zero (so that shrinkage hardly occurs), and the difference between the shrinkage rates of both is further increased. May be. The same applies to a means for providing a difference in a predetermined range between the radial contraction rate of the press-fitting portion 31 of the inner ring 12 and the radial contraction rate of the pressing portion 47 of the union nut 13, which will be described later.

The heat treatment here is, for example, for the purpose of removing internal strain from a molded product molded when the inner ring 12 is manufactured, the molded product is heated at a predetermined temperature for a predetermined time (for example, the material is PFA or PTFE). In the case of (1), heating is performed (annealing) in the range of about 200° C. to about 250° C. for about 180 minutes, and when the material is ETFE, about 180° C. in the range of about 120° C. to about 140° C.

Further, in the present embodiment, the difference between the radial contraction rate of the connecting portion 46 of the union nut 13 and the radial contraction rate of the press-fitting portion 31 of the inner ring 12 is about 0.05% to about 10%. It is set to a value within the range. Preferably, the difference in shrinkage between the two is set to a value within the range of about 0.05% to about 5%. The same applies to the difference between the radial shrinkage rate of the press-fitting portion 31 of the inner ring 12 and the radial shrinkage rate of the pressing portion 47 of the union nut 13, which will be described later.

With such a configuration, when the inner ring 12 and the union nut 13 are heated by heat transfer from a fluid or the like and then cooled in a state where the tube 2 is joined to the resin pipe joint 1 (thermal cycle (When loaded), the connecting portion 46 of the union nut 13 can be contracted in the radial direction to a greater extent than the press-fitting portion 31 of the inner ring 12.

Therefore, when the resin pipe joint 1 is joined to the tube 2, the inner diameter of the connecting portion 46 of the union nut 13 is smaller than the outer diameter of the press-fitting portion 31 of the inner ring 12. Since it becomes large, one end portion 5 in the longitudinal direction of the tube 2 supported from the inside in the radial direction by the press-fitting portion 31 is joined from the outside in the radial direction by the connecting portion 46 that is overlapped in the radial direction with the outer tubular portion 22. The power to hold (hold) can be strengthened.

Therefore, when a pulling force is applied to the tube 2 so as to pull out the tube 2 from the resin pipe fitting 1, the outer tubular portion 22 is pushed inward in the radial direction by the connecting portion 46 of the union nut 13. The frictional force generated between the tube 2 and the tube 2 can be increased. As a result, the withdrawal resistance of the tube 2 in the resin pipe joint 1 can be improved.

Further, in the present embodiment, the union nut 13 has the pressing portion 47, and the radial contraction rate of the pressing portion 47 of the union nut 13 is the radial contraction of the press fitting portion 31 of the inner ring 12. Since it is set to be larger than the ratio, the diameter reduction amount of the inner diameter of the pressing portion 47 of the union nut 13 is smaller than the diameter reduction amount of the outer diameter of the press-fitting portion 31 of the inner ring 12, like the connecting portion 46. Therefore, the pressing force of the pressing portion 47 (more specifically, the corner portion 48) on the one end 5 side in the longitudinal direction of the tube 2 can be strengthened (holding) from the outside in the radial direction.

Therefore, in order to pull out the tube 2 from the resin pipe joint 1, when a pulling force is applied to the tube, the pressing portion 47 of the union nut 13 and the tube 2 are outside the joint body 11. The frictional force generated between them can be increased. As a result, the pull-out resistance of the tube 2 in the resin pipe joint 1 can be further improved.

The above-mentioned effects can be confirmed by conducting a comparative experiment on the withdrawal resistance of the tube. In this comparative experiment, first, Example 1 and Example 2 of the present invention were prepared, and the shrinkage rate different from that of the present invention having the same structure as the resin pipe joint 1 and the inner ring and the union nut was obtained. Comparative Example 1, Comparative Example 2, and Comparative Example 3 having a difference were prepared.

Next, the atmospheric temperature of each of Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3 was raised from room temperature to about 200° C., thereby heating each at about 200° C. for 1 hour. After that, the atmospheric temperature was lowered from about 200° C. to room temperature to naturally cool each of Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3.

It should be noted that this heating and natural cooling is performed in a state before each of Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3 is joined to the tube (each inner ring and union nut are mutually In a state where it was separated and also separated from the joint body), it was carried out for each of Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3.

As shown in FIGS. 2 and 3, with respect to Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3, the press-fitting portion of the inner ring before and after temperature fluctuation (heating), respectively. Measure the outer diameter, the inner diameter of the connecting part of the union nut, and the inner diameter of the pressing part to determine the radial shrinkage of the press fitting part, the radial shrinkage of the connecting part, and the radial shrinkage of the pressing part. The rate was calculated.

Then, as shown in FIG. 4, the difference between the shrinkage rate in the radial direction at the connecting portion of the union nut and the shrinkage rate in the radial direction at the press-fitting portion of the inner ring was calculated. Further, the difference between the shrinkage rate in the radial direction at the pressing portion of the union nut and the shrinkage rate in the radial direction at the press-fitting portion of the inner ring was calculated.

Here, Example 1 includes an inner ring made of PTFE and a union nut made of PFA. The difference in the radial shrinkage of the union nut at the connecting portion is 0.45% greater than the radial shrinkage of the inner ring at the press-fitting portion. Further, the radial contraction rate of the pressing portion of the union nut is 0.06% greater than the radial contraction rate of the press-fitting portion of the inner ring.

The second embodiment includes an inner ring made of PTFE and a union nut made of ETFE. Further, the radial contraction rate of the connecting portion of the union nut has a difference of 0.34% from the radial contraction rate of the press-fitting portion of the inner ring. The radial contraction rate of the pressing portion of the union nut is 0.06% more than the radial contraction rate of the press-fitting portion of the inner ring.

Comparative Example 1 includes an inner ring made of PFA and a union nut made of PFA. The shrinkage in the radial direction at the connecting portion of the union nut is 0.04% less than the shrinkage in the radial direction at the press-fitting portion of the inner ring. The radial contraction rate of the pressing portion of the union nut is 0.44% lower than the radial contraction rate of the press-fitting portion of the inner ring.

Comparative Example 2 includes an inner ring made of ETFE and a union nut made of ETFE. The shrinkage rate in the radial direction at the connecting portion of the union nut is 0.02% less than the shrinkage rate in the radial direction at the press-fitting portion of the inner ring. The radial contraction rate of the pressing portion of the union nut is 0.30% less than the radial contraction rate of the press-fitting portion of the inner ring.

Comparative Example 3 includes an inner ring made of PTFE and a union nut made of PTFE. Further, the radial shrinkage of the union nut in the connecting portion has a difference of 0.02% from the radial shrinkage of the inner ring in the press-fitting portion. The radial contraction rate of the pressing portion of the union nut is the same as the radial contraction rate of the press-fitting portion of the inner ring.

Then, for each of Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3, a PFA tube was joined so as to assemble the inner ring and the union nut to the corresponding joint body. Then, a thermal cycle (normal temperature→high temperature (about 200° C.)→normal temperature) was applied. Then, the withdrawal resistance ratio of the tube was measured before and after the thermal cycle.

The pull-out resistance ratio of the tube here means the pull-out resistance value of the tube after each of 0 to 5 thermal cycles and is measured before the thermal cycle (that is, when the number of thermal cycles is O times). It is a comparison with the pull-out resistance, specifically, the pull-out resistance of the tube after the heat cycle is divided by the pull-out resistance of the tube before the heat cycle.

From the measurement results shown in FIG. 5, it was found that in Examples 1 and 2, the pull-out resistance ratios of the tubes were larger than those in Comparative Examples 1, 2, and 3. That is, according to the present invention, it has been clarified that there is an effect of improving the pull-out resistance of the tube even when the thermal cycle is repeatedly applied.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. Therefore, it is to be understood that the invention, within the scope of the appended claims, may be practiced otherwise than as described herein.

DESCRIPTION OF SYMBOLS 1 Resin pipe joint 2 Tube 5 One end part in the longitudinal direction of the tube 11 Joint body 12 Inner ring 13 Union nut 22 Outer tube part (tube part)
31 press-fitting part 46 connecting part 47 pressing part

Claims (2)

In a resin pipe joint that can be joined to the tube in a state where one end in the longitudinal direction of the tube is inserted inside,
A joint body having a tubular portion into which one end in the longitudinal direction of the tube can be inserted,
A press-fitting portion that can be press-fitted into one side of the tube in the longitudinal direction, the press-fitting portion that can be inserted into the tubular portion together with the one end in the longitudinal direction of the tube in a state of being press-fitted to the one side of the longitudinal direction of the tube. With an inner ring,
In order to connect the one end side of the tube in the longitudinal direction to the joint body, the press-fitting portion is inserted into the tubular portion together with the one end in the longitudinal direction of the tube, and in the radial direction between the press-fitting portion and the press-fitting portion. A union nut having a connecting portion that can be screwed to the outer peripheral portion of the joint body so as to sandwich one end portion in the longitudinal direction of the tube,
The inner ring and the union nut are made of resin materials different from each other, and each has a property of contracting with a change in ambient temperature,
A resin pipe joint in which a radial contraction rate in the connecting portion of the union nut is set to be 0.05% or more larger than a radial contraction rate in the press-fitting portion of the inner ring. The union nut is
In the state where the press-fitting portion is inserted into the tubular portion together with the longitudinal end portion of the tube, as the connecting portion is screwed with respect to the outer peripheral portion of the tubular portion, the longitudinal end portion of the tube A pressing part that can press the part side from the outside in the radial direction toward the press-fitting part,
The resin pipe joint according to claim 1, wherein a radial shrinkage rate of the pressing portion of the union nut is set to be larger than a radial shrinkage rate of the press-fitting portion of the inner ring.

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