JP2010127427A - Resin pipe joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin pipe joint improved to be excellent in assembly workability and handling properties by making it possible to confirm that tightening a union nut is ended or is almost ended even when a pipe joint is placed in invisible or less visible place or even in a noisy work site. <P>SOLUTION: In the resin pipe joint, the union nut 2 advances by screwing a male screw 5 into a female screw 8 in a state that a tube 3 is externally suitable for an inner cylinder 4 to form a diameter-enlarged part 3A, and a diameter-enlarged change region 9 is thrust by a seal thrusting part 10. By tightening the union nut 2 just before the end of advancing by pressing a diameter-enlarged change region 9 via a sealing thrusting part 10, either the recess 20 of a flange 1A of a joint body 1 or a projection 19 projected at an end of the union nut 2 is bent in the radial direction for engagement or separation so as to generate a sharp torque change. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a resin pipe joint having a structure in which a tube as a fluid transfer path is expanded (flared) and connected, and more specifically, in various technical fields such as semiconductor manufacturing, medical / pharmaceutical manufacturing, food processing, chemical industry, etc. It is also suitable for piping of high-purity liquid and ultrapure water handled in the manufacturing process, and relates to a resin pipe joint used as a connecting means of a tube that is a fluid device such as a pump, a valve, a filter, or a fluid transfer path. .

  As this type of resin pipe joint, a tube joint disclosed in Patent Document 1 is known. That is, the tube (1) made of synthetic resin is forcibly pushed into the fitting cylinder (5) of the joint body (4), or as shown in FIG. Is expanded to fit into the fitting cylinder (5). Then, the union nut (6) fitted in the tube in advance is screwed into the joint body, and tightened to forcibly move in the axial direction of the joint body (4), thereby expanding the tube (1). The diameter root portion (2a) is strongly pressed in the axial direction by the edge portion (6a) to seal between the tube (1) and the fitting tube (5).

  A resin pipe joint disclosed in FIGS. 8 and 9 of Patent Document 2 is also known as the same structure as described above. Further, as disclosed in FIG. 5 of Patent Document 2 and Patent Document 3, a tube end that is externally expanded to the inner ring is fitted into a fitting cylinder of a joint body, and the tube is tightened by a union nut. There is also a resin pipe joint having a structure in which a diameter-enlarged portion to the inner ring is pressed and sealed. In any case, the tube end is expanded (flared) and sealed with a union nut. In the former structure in which the end of the tube is fitted outside the fitting cylinder part and is fastened with a nut, there is a merit that a pipe joint can be economically configured with two parts of a joint body and a union nut. With the structure, it is possible to reliably avoid leakage, obtain stable performance, and have excellent reliability.

  By the way, in actual construction of resin pipe joints having various excellent merits as described above, there is a chronic improvement item that it is difficult to understand the end point of union nut tightening. Originally, in the joint made of resin, due to the characteristics of the material, the tightening torque gradually increases with respect to the union nut turning operation, so the feeling of closing due to the sudden increase in the tightening torque like a metal material is poor, It is difficult to understand the end of tightening sensuously. Insufficient tightening may cause leakage, and excessive tightening may damage the joint. Since it is made of resin, those inconveniences are likely to occur, and it is necessary to finish tightening the union nut correctly.

  For example, if the pipe joint is exposed and deployed in a state where the operator can see completely, the tightening end state is confirmed by the position confirmation of the screwing condition accompanying the tightening of the union nut, or close to it. It is relatively easy to know that it will be in a state. However, pipe joints are often placed in narrow spaces between other devices, hidden places behind the ceiling, etc., and are often not visible or difficult. It is often a tightening operation. Therefore, it has been necessary to notify the operator by some means that the union nut has been tightened or has come to an end even if it cannot be visually recognized.

Therefore, in Patent Document 3, a projecting piece (15) projecting in the axial direction in a cantilevered state on the joint body (1), and a protrusion formed on the end of the union nut (2) in the axial direction ( When the union nut (2) is about to end tightening, it comes into close contact with each other in the circumferential direction and comes into contact with it. A technique is disclosed that makes it possible to know that the person is approaching. That is, it is a sound generating means that informs the operator of the tightening end state by sound.
Noto 3041899 Japanese Patent Laid-Open No. 7-27274 Japanese Patent Laid-Open No. 11-230463

  Even if the pipe joint portion is not visible, the sound generating means enables confirmation by the sound recognition of the tightening end state by the union nut operation, and a certain effect can be obtained. However, the actual piping work site is rarely in a quiet situation, and it is in a certain level of noise conditions, such as working in a factory that is in operation or other work and construction work being done together Will be done. Therefore, it is often impossible for the operator to hear the sound of the resin protruding piece, and there is still room for further improvement as means for notifying the end of tightening of the union nut, that is, a means for recognizing the end of tightening. It was a thing.

  In view of the above circumstances, the object of the present invention is that the union nut is at or near the end of tightening even at a work site where the pipe joint portion is invisible or difficult to see and under noise conditions. This is to provide a resin pipe joint that can be confirmed and improved so as to be excellent in assembly workability and handling.

The invention according to claim 1 is a synthetic resin joint body 1 including a fitting portion 4 that can be fitted and mounted by expanding the diameter of an end portion of the synthetic resin tube 3, and a male screw 5.
A union nut 2 made of a synthetic resin including a female screw 8 that can be screwed into the male screw 5 and a sealing pressing portion 10 that can act on a diameter expansion change region 9 in the diameter expansion portion 3A of the tube 3;
The union nut 2 is screwed in the axial direction P of the joint body 1 by screwing the female screw 8 into the male screw 5 in a state in which the tube 3 is fitted and attached to the fitting cylinder 4. In the resin pipe joint configured such that the expanded diameter change region 9 is pressed in the axial center P direction by the sealing pressing portion 10 to form the sealing portion S.
A concave portion 20 that is recessed in the radial direction is formed on the outer peripheral portion of the joint body 1, and a convex portion 19 that protrudes in the radial direction is formed on the outer peripheral portion of the end portion in the axis P direction of the union nut 2. With the tightening rotation from near the end of screwing of the union nut 2 when the pressing portion 10 presses the diameter expansion change region 9, the concave portion 20 and the convex portion 19 are in one radial direction thereof. The torque fluctuation portion 26 is configured to be fitted and detached from each other by a deflection displacement.

  The invention according to claim 2 is the resin pipe joint according to claim 1, wherein a plurality of the recesses 20 and / or the protrusions 19 are formed in the circumferential direction, and the union nut 2 is rotated once. The fitting and detachment are configured to be repeated.

  The invention according to claim 3 is the resin pipe joint according to claim 2, wherein the concave portion 20 and / or the convex portion 19 are formed at equal angles with respect to the axis P in the circumferential direction. To do.

  According to a fourth aspect of the present invention, in the resin pipe joint according to any one of the first to third aspects, the concave portion 20 and / or the convex portion 19 has an arc shape as viewed in the axial center P direction. It is characterized by this.

  The invention according to a fifth aspect is the resin pipe joint according to any one of the first to fourth aspects, wherein the concave portion 20 is a radially inward concave portion opened toward a radially outer side, and the convex portion 19 is It is a radially inward convex part protruding toward the radially inner side.

  The invention according to claim 6 is the resin pipe joint according to any one of claims 1 to 5, wherein the convex portion 19 is formed in a cantilever arm shape extending from the union nut 2 in the axis P direction. It is characterized by being formed.

  The invention according to claim 7 is the resin pipe joint according to any one of claims 1 to 6, wherein the joint body 1 and the union nut 2 are made of a fluororesin.

  According to the first aspect of the present invention, as will be described in detail in the section of the embodiment, the action of the torque fluctuation portion accompanying the tightening rotation of the union nut, that is, in the radial direction of either the concave portion or the convex portion. The torque fluctuation due to the fitting and disengaging with each other due to the bending displacement becomes large, and the torque fluctuation can be clearly sensed through a tool (spanner, wrench, etc.) for turning the union nut. Therefore, since a large torque fluctuation occurs when the end or end of tightening approaches, it is possible to recognize that the end of tightening or almost end of the union nut with an operational feeling. As a result, it is possible to confirm that the union nut has been tightened or close to it even at work sites where the pipe joint is not visible or difficult to see, and under noisy conditions. It is possible to provide a resin pipe joint that is improved so as to have excellent workability and handling properties.

  If a plurality of concave portions and convex portions are formed in the circumferential direction as in claim 2, and the engagement and disengagement during one rotation of the union nut are repeated, the frequency of the large torque fluctuation described above increases. Thus, there is an advantage that the sensory recognition becomes clearer and the effect of the invention of claim 1 is enhanced. In this case, as in claim 3, it is preferable to form the concave portions and the convex portions at equal angles in the circumferential direction because a plurality of the fittings and disengages are overlapped, and the torque fluctuation becomes more remarkable.

  As a means for forming the concave portion or the convex portion, as shown in claim 4, the concave portion or the convex portion is formed so as to exhibit an arc shape when viewed in the axial direction, or the concave portion is recessed toward the radially outer side as in claim 5. For example, the convex portion can be formed into a cantilevered arm extending in the axial direction from the union nut.

  According to the invention of claim 7, since both the joint body and the union nut are formed of a fluorine-based resin having characteristics excellent in chemical resistance and heat resistance, even if the fluid is a chemical liquid or a chemical liquid, Or even if it is a high-temperature fluid, a joint structure part does not deform | transform and it becomes easy to leak, and favorable sealing property and drawing-out force can be maintained now. Note that the fluorine-based resin is preferable in that it is stable at high temperatures, excellent in water repellency, has a small coefficient of friction, has extremely high chemical resistance, and has high electrical insulation. Further, if the joint body and the union nut are formed of the same fluororesin material, the linear expansion coefficients are also the same, and there is an advantage that the sealing performance at high temperature is improved.

  Embodiments of a resin pipe joint according to the present invention will be described below with reference to the drawings. 1 to 3 are sectional views showing the structure of a resin pipe joint, FIG. 4 is an axial direction view of the main part showing the concave part, FIG. 5 is an axial direction view of the main part showing the convex part, and FIG. 7 is a plan view showing an end state, FIG. 7 is an axial direction view of a main part showing a tightening end recognizing means, FIG. 8 is a cross-sectional view of the main part showing a situation where the convex part is bent and the remaining mountain part is passed over, FIG. FIG. 10 is a view showing a torque fluctuation graph accompanying union nut tightening, and FIG. 10 is a plan view showing a final tightening state.

[Example 1]
As shown in FIGS. 1 and 2, the resin pipe joint A according to Example 1 includes a tube 3 made of a fluororesin (an example of a synthetic resin typified by PFA, PTFE, etc.), a fluid device such as a pump and a valve, A joint body 1 made of fluororesin (an example of a synthetic resin typified by PFA, PTFE, etc.) and a fluororesin (synthetic resin typified by PFA, PTFE, etc.) are connected to tubes of different diameters or the same diameter. An example) It is comprised by two parts with the union nut 2 made from. 1 and 2 show an assembled state in which the union nut 2 is tightened by a predetermined amount.

  As shown in FIGS. 1 and 2, the joint main body 1 includes an inner cylinder 4 (one example of a fitting cylinder) 4 that can be externally fitted by expanding the diameter of the end of the tube 3, and an inner depth of the inner cylinder 4. A cover cylinder portion 6 having a circumferential groove (an example of a “radial gap”) m extending in the axial center P direction to allow entry of the distal end of the tube 3 whose diameter is increased on the outer peripheral side of the side portion, and a trapezoid It is formed in the cylindrical member provided with the external thread 5 which consists of a screw, and the cylindrical fluid-like fluid path | route 7 with the axial center P. As shown in FIG. The inner cylinder 4 has a tapered straight shape having a tapered tip portion 4A for gradually expanding the diameter of the tube 3 and a straight barrel portion 4B formed on the large diameter side of the tapered tip portion 4A. It is structured as a thing.

  In the circumferential groove m, the outer peripheral surface that is the inner peripheral surface of the diameter is the outer peripheral surface 4b of the straight barrel portion 4B, and the outer peripheral surface that is the outer peripheral surface of the diameter is the inner peripheral surface 6a of the cover cylindrical portion 6. . A joint flange 1A is formed at a position away from the inner peripheral surface 21 of the circumferential groove m in the axial center P direction by a predetermined length, and the outer peripheral surface of the end portion of the cover cylinder portion 6 from the substantially root portion of the joint flange 1A. A male screw 5 is formed over the entire area. The tip surface of the inner cylinder 4 is provided with a reverse taper angle closer to the inner back side (back side in the direction of the axis P) toward the inner side in the radial direction, that is, a cut surface 16 having a larger diameter toward the tip is formed. The shape of the liquid pool peripheral portion 17 resulting from the displacement of the inner peripheral surface of the tube 3 toward the enlarged diameter portion (flare portion) is defined as the inner peripheral side expanded shape, and the fluid is stored in the liquid pool peripheral portion 17. It is hard to be stagnant. The cut surface 16 is formed so that the maximum diameter thereof is a substantially intermediate value between the inner diameter and the outer diameter of the tube 3 in the natural state, but this is not particularly concerned.

  As shown in FIGS. 1 and 2, the union nut 2 includes a female screw 8 that can be screwed into the male screw 5, and a small-diameter side of the enlarged-diameter changing region 9 in the enlarged-diameter portion 3 </ b> A that is externally fitted to the inner cylinder 4 of the tube 3. A peripheral edge for sealing (an example of a pressing portion for sealing) 10 that can act on the end portion, a circumferential edge 11 for retaining that can act on the large-diameter side end portion of the diameter expansion change region 9, and a diameter in the expanded diameter portion 3A The presser inner peripheral portion 13 that can be externally fitted to the diameter-enlarging straight portion 12 that is surrounded by a certain straight barrel portion 4B, and the tube 3 is placed over a predetermined length in the axis P direction following the sealing peripheral edge 10. And a guide cylinder portion 14 that surrounds the guide cylinder portion 14.

  The sealing peripheral edge 10 has an inner diameter substantially equal to the outer diameter of the tube 3, and the pressing surface 10 a is a side peripheral surface orthogonal to the axis P. The diameter of the circumferential edge 11 for retaining is larger than that of the outer peripheral surface 4b of the straight barrel portion 4B whose inner peripheral surface is the maximum diameter of the inner tube 4, and the diameter obtained by adding the wall thickness of the tube 3 That is, although it is set to a value smaller than the diameter of the presser inner peripheral portion 13, it may not be so (for example, a smaller diameter than the outer peripheral surface 4 b), and if it acts on the large diameter side portion of the diameter expansion change region 9. good. The pressing surface 11a of the retaining peripheral edge 11 is also a side peripheral surface orthogonal to the axis P.

  The presser inner peripheral portion 13 has no radial clearance between the presser inner peripheral portion 13 and the enlarged diameter straight portion 12 so that the enlarged diameter portion 3A is not rotated by tightening of the union nut 2. The retaining means N is configured to be set to a value that is press-fitted (press-fit externally fitted). This is because when the union nut 2 is tightened, the retaining peripheral edge 11 presses the enlarged diameter straight portion 12 in the axial direction so as to prevent the tube 3 from being pulled out. This is to prevent the portion 12 from escaping so as to swell outward in the radial direction, and to increase the pull-out force by cooperating with the peripheral edge 11 for retaining.

  Next, in order to externally insert the end of the tube 3 into the inner cylinder 4, the tube 3 is forcibly pushed in at room temperature to increase the diameter, or it is warmed using a heat source so as to be easily deformed by expansion. The tube end 3t is formed as a cover tube as shown in FIG. 1 by pushing it into the inner tube 4 after expanding the tube end in advance using a diameter expander (not shown). Insert until the end wall 15 of the portion 6 is located inward. As shown in FIGS. 1 and 2, the enlarged diameter portion 3A that is externally fitted to the inner cylinder 4 includes an enlarged diameter changing region 9 that is fitted externally to the outer peripheral surface 4a of the tapered tip portion 4A, and a straight body. It consists of the diameter-expanded straight part 12 fitted on the outer peripheral surface 4b of the cylinder part 4B.

  That is, as shown in FIGS. 1 and 2, the shaft center of the joint body 1 by tightening the union nut 2 by screwing the female screw 8 with the male screw 5 in a state in which the tube 3 is fitted on the inner cylinder 4. Due to the screwing in the P direction, the presser inner peripheral portion 13 is externally fitted to the enlarged diameter straight portion 12, and a portion having a larger diameter than the diameter of the inner cylinder 4 in the larger diameter side portion of the enlarged diameter changing region 9 is formed. It is set so that it is pressed in the axis P direction by the circumferential edge 11 for retaining, and the small diameter side portion of the diameter change region 9 is pressed in the axis P direction by the sealing edge 10. Note that the diameter of the fluid transfer path 3W of the tube 3 and the diameter of the fluid path 7 are set to be the same diameter in order to obtain a smooth fluid flow, but may be different from each other.

  In this case, as described above, there is no gap in the radial direction between the presser inner peripheral portion 13 and the enlarged diameter straight portion 12, and the enlarged diameter straight portion 12 is provided between the straight barrel portion 4B and the presser inner peripheral portion 13. It is in the state where it is clamped. Moreover, in Example 1, the diameter-expansion change area | region 9 of the tube 3 is formed as a part which the front-end | tip narrows and covers 4 A of cylinder parts. The diameter expansion change region 9 is a state of a taper tube that gradually expands, and the sealing peripheral edge 10 and the retaining peripheral edge 11 are in a positional relationship apart from each other in the axis P direction, but the tip tapered tube As the angle of the outer peripheral surface 4a of the portion 4A with respect to the axial center P becomes steeper, the distance in the axial center P direction between the sealing peripheral edge 10 and the retaining peripheral edge 11 becomes closer. Further, the sealing peripheral edge 10 and the tip of the inner cylinder 4 are slightly separated in the direction of the axis P (see FIG. 2 and the like), but if the angle of the outer peripheral surface 4a becomes steep, the separation distance is increased, If it becomes loose, the distance is reduced.

  As shown in FIGS. 1 and 2, in a predetermined assembled state of the resin pipe joint A, the sealing peripheral edge 10 has the small diameter side end portion of the diameter expansion change region 9 of the tube 3 in the axis P direction. Since the pressing is performed, the small diameter side end of the outer peripheral surface 4a of the diameter expansion change region 9 and the inner peripheral surface of the tube 3 in contact with the portion are strongly pressed to form the seal portion S. The tube 3 and the joint body 1 are well sealed by the seal portion S at the tip of the inner tube 4 without any fluid such as cleaning liquid or chemical solution entering between the inner tube 4 and the enlarged diameter portion 3A.

  The diameter-enlarging straight part 12 of the diameter-enlarging part 3A that is press-fitted to the inner cylinder 4 is surrounded by the outer peripheral surface 4b of the straight cylinder part 4B and the presser inner peripheral part 13, and is first expanded and deformed. The retaining peripheral edge 11 is positioned so as to substantially bite into the enlarged diameter straight portion 12. This resists the pulling force acting on the enlarged diameter portion 3A due to the catch of the retaining peripheral edge 11 that pushes the large diameter side end portion of the enlarged diameter change region 9 so as to substantially bite into the enlarged diameter straight portion 12. In addition, the diameter-enlarged straight portion 12 can be expanded and deformed in the radial direction by the pulling force with the retaining peripheral edge 11 as a starting point. It also comes to be.

  If the diameter-enlarged portion 3A is displaced in the axial center P direction even a little, the seal point in the seal portion S may be shifted and the seal function may be uncertain, but this is prevented in advance. Accordingly, the retaining means N is configured in which the movement of the diameter-enlarged portion 3A in the direction of coming out of the inner cylinder 4 in the direction of the axis P is firmly restricted, thereby realizing an excellent pull-out resistance. As a result, the flare-type resin pipe joint A composed of the joint body 1 and the union nut 2 can be easily assembled by nut operation in a state where the tube is attached to the inner cylinder, and has excellent assemblability. It has been realized as an improved product that can achieve both excellent sealing performance by the seal portion S and excellent pull-out resistance by the retaining means N.

  In addition, after the pressing of the large-diameter side portion of the enlarged-diameter changing region 9 by the retaining peripheral edge 11 is started, the pressing of the small-diameter side portion of the enlarged-diameter changing region 9 by the sealing peripheral edge 10 is started. Depending on the setting, that is, the pressing time difference means, there are the following operations and effects. That is, as shown in FIG. 3, when the union nut 2 is turned and tightened (screwed), first, the retaining peripheral edge 11 is first moved to the diameter expansion change region 9 (specifically, the diameter expansion change region). 9 at that time, the sealing peripheral edge 10 has not yet reached the diameter expansion change region 9. As a result, only the retaining peripheral edge 11 pushes the large-diameter side portion of the expanded diameter change region 9, more specifically, the portion having a larger diameter than the straight barrel portion 4 </ b> B in the axial center P direction. The tightening operation causes an action to push the enlarged diameter straight portion 12 further into the inner side of the inner cylinder 4.

  The diameter-enlarging straight portion 12 that is press-fitted and fitted to the straight barrel portion 4B is also pressed against the inner circumference portion 13 of the presser, but when the pressure-contact force is relatively weak, the diameter-enlarging portion 3A is displaced to move the inner cylinder 4 In order to insert the tube into the joint body 1 more reliably, the expanded diameter straight portion 12 pushed in the direction of the axis P is moved in the direction of the axis P. Due to the difficulty, it is possible to obtain a favorable effect that the pressure contact force is further increased and the action of being firmly clamped is generated in an attempt to expand in the radial direction. When the pressure contact force is relatively strong, the diameter-enlarging straight portion 12 pushed in the direction of the axis P is not able to move in the direction of the axis P first, thereby causing a strong action to expand in the radial direction. The effect that the diameter-expanded straight portion 12 is held more firmly with the presser inner peripheral portion 13 is obtained.

  That is, in any case, when the sealing peripheral edge 10 is not pierced into the enlarged diameter portion 3A, the retaining peripheral edge 11 pushes the enlarged diameter portion 3A in the direction of the axis P, thereby causing the straight barrel portion 4B. The press-holding force of the enlarged diameter straight portion 12 by the presser inner peripheral portion 13 is enhanced. For example, as shown in FIG. 2, the corner space portion formed by the pressing surface 11 a and the presser inner peripheral portion 13 is formed by the portion pressed by the retaining peripheral edge 11 in the enlarged diameter portion 3 </ b> A flowing outward in the diameter. There is a possibility that a phenomenon in which a portion where the outer diameter restriction by the presser inner peripheral portion 13 is released expands to the outer diameter side and a rising portion (not shown) is formed may occur.

  As described above, the pressing time difference means provides an effect of further improving both the pressure contact holding force of the tube 3 with respect to the inner cylinder 4 and the pull-out resistance. The union nut 2 of the phantom line shown in FIG. 3 shows when the sealing peripheral edge 10 has reached the diameter expansion change region 9 (specifically, the small diameter side portion of the diameter expansion change region 9). The peripheral edge 11 has already digged into the enlarged diameter change region 9 clearly.

  As shown in FIGS. 1 and 2, a tube is formed by a circumferential groove m formed by the inner back side of the inner tube 4 and the cover tube portion 6, and a union nut 2 formed by a fluororesin that can be seen through. Indicator means B is configured to visually check whether 3 is correctly inserted into the inner cylinder 4 or not. That is, the enlarged-diameter portion 3A is visually observed on a line (see arrow A in FIG. 2) passing through the valley-like inner peripheral surface 22 between the inner periphery of the presser inner peripheral portion 13 and the internal thread 8. If the tube 3 is in a normal state where it can be seen and the diameter-expanded end 3t is not visible, it can be determined that the tube 3 is correctly fitted on the inner cylinder 4. If the insertion failure state in which the enlarged diameter portion 3A can be seen and the enlarged diameter end portion 3t can be seen, or the insufficient diameter insertion portion in which the enlarged diameter portion 3A itself cannot be seen, the insertion of the tube 3 is still at the specified amount. In this case, an operation of further pushing the tube 3 is performed until the normal state is visible.

  In the indicator means B, the union nut 2 is formed using a transparent or translucent (milky white or the like) fluororesin so that an object inside thereof can be visually confirmed. On the side and through the valley-shaped inner peripheral surface 22 up to the internal thread 8 (see arrow A in FIG. 2), the diameter-enlarged portion is obtained by seeing only the portion where the thickness of the union nut 2 is small. 3A is relatively clearly visible. On the other hand, the visibility of the enlarged diameter portion 3A is inferior at the part of the presser inner peripheral part 13 which is thicker than the part of the valley-shaped inner peripheral surface 22, and is difficult to see.

  And since the union nut 2 and the cover cylinder part 6 have overlapped in the part of the circumferential groove m in which the edge part of the tube 3 can enter, even if the joint main body 1 can also be seen through, thickness is a valley-shaped inner peripheral surface. In addition to being thicker than the portion 22, a change in the refractive index at the boundary surface due to the overlap of the male screw 5 and the female screw 8 is also added, so that it is impossible to visually recognize where the enlarged diameter end 3 t is located. In addition, when the joint body 1 is not transparent such as being colored, it is needless to say that the enlarged diameter portion 3A or the enlarged diameter end portion 3t is seen on the inner and inner side of the end wall 15 of the cover cylinder portion 6. I can't.

  Therefore, the union nut 2 was tightened by the function of the indicator means B whether or not a normal state in which the enlarged diameter portion 3A can be seen from the valley-shaped inner peripheral surface 22 and the enlarged diameter end portion 3t cannot be seen. A resin pipe joint A that can be visually confirmed in a later assembled state and that is convenient and excellent in usability can be provided.

  Further, the presence of the circumferential groove m and the cover cylinder portion 6 for constituting the indicator means B also provides an effect of functioning as an indicator when the tube 3 is inserted into the inner cylinder 4. That is, it can be confirmed whether or not the amount of insertion into the inner cylinder 4 by flaring the tube 3 is a predetermined amount. That is, it is sufficient that the end 3t as the enlarged diameter portion 3A inserted into the inner cylinder 4 is deeper than the end wall 15, and as a means for visually judging whether the tube 3 is assembled to the inner cylinder 4 or not. There is an advantage to function.

  Here, the fitting length to the inner cylinder 4 in the direction of the axis P of the enlarged diameter portion 3A is L (expanded fitting length L), and the distance from the tip of the inner cylinder 4 to the end wall 15 of the cover cylinder portion 6 Is D (minimum fitting length D), and the maximum tube fitting length of the circumferential groove m is d (adjustment fitting length d), the expanded fitting length L is equal to or greater than the minimum fitting length D. In addition, it is only necessary to set the length to be equal to or shorter than the minimum fitting length D plus the adjustment fitting length d, and this can be known by the indicator means B even after the union nut 2 is tightened. That is, if D ≦ L ≦ (D + d), the amount of insertion of the tube 3 into the inner cylinder 4 is an appropriate amount.

  Standard test of how much force is pulled in the direction of the axis P when the tube 3 is inserted into the inner cylinder 4 without operating the retaining edge 11 and the tube 3 comes out of the inner cylinder 4 The results obtained using the tube 3 having a different diameter are described below. As an example of a standard diameter, when an inner diameter of 15.8 mm and an outer diameter of 19 mm are used, the pulling force is ○ when L = 5 mm, the pulling force is ◎ when L = 10 mm, and the pulling force is L = 15 mm. The result was that the force was ◎. Here, if the pull-out force is 80 kg or more, the determination is “good”, and if it is 90 kg or more, the determination is “good”. From this, if L is at least 10 mm, good pull-out resistance can be realized, so that L ≧ 10 mm is obtained. In this case, there is no upper limit for L, but if this is the case, the circumferential groove m becomes longer and the axial length of the pipe joint becomes larger.

  By the way, in order to cut the tube 3 with an appropriate length, a cutting tool is used to cut the tube 3 accurately. Usually, however, an ordinary worker usually cuts with a scissor. Often, the cut end is not exactly perpendicular to the tube axis but is cut obliquely. Since it is known from the data that the variation in the axial direction position of the cut surface due to the oblique cut is about 5 mm at the maximum, the substantial depth of the circumferential groove (length in the axial center P direction), that is, d = 5. L ≦ 15 mm as a result, and as a result, 10 mm ≦ Lmm ≦ 15 mm (D = 10 mm, D + d = 15 mm), the cut surface of the tube 3 is inclined, and the length in the axis P direction as a pipe joint is as much as possible. The tube 3 and the inner cylinder 4 can be fitted in a state having a sufficient pulling-out force while considering both of the restraining.

  Therefore, the position of the expanded diameter end portion 3t in the axis P direction is OK as long as it is slightly behind the end wall 15 of the cover tube portion 6 as shown by the solid line in FIGS. The amount of insertion into the inner cylinder 4 is OK, and as shown by the phantom line in FIG. 2, it may be inserted up to a position near the inner back end of the circumferential groove m. Of course, if L <D, the insertion is insufficient, and it goes without saying that the tube 3 is pushed further. The specific lengths of 10 mm and 15 mm described above are only examples, and the actual values take into consideration various conditions such as the material, diameter, thickness, and diameter expansion to the inner cylinder 4 of the tube 3. It is determined appropriately.

  The resin pipe joint A is provided with a tightening end recognition means C capable of notifying an operator with an operational feeling that the end or end of tightening of the union nut 2 in the assembled state is approaching. . As shown in FIGS. 1 to 3, 6, and 7, the tightening end recognizing means C is a recess formed at eight locations on the flange 1 </ b> A of the joint body 1 at every equal angle (45 degrees around the axis P). 20 and torque fluctuations formed by projecting portions 19 projecting inward in the radial direction at eight positions at equal angles (45 degrees around the axis P) on the tip end side (side end of the female screw 8) of the union nut 2. It is configured by providing the portion 26.

  As shown in FIGS. 2, 4, and 6, the recess 20 of the joint body 1 is formed so as to be recessed in an arc shape in the radially inward direction at the outer periphery of the flange 1 </ b> A, and between the recesses 20 adjacent in the circumferential direction. Has a structure in which a remaining mountain portion 24 protruding outward is formed. The outer peripheral surface of the remaining mountain portion 24 is formed on the maximum outer peripheral surface 1a having a constant diameter, and the side peripheral surface on the male screw side is formed on the intermittent side peripheral surface 1b. Further, on the side opposite to the male screw 5 in the axial center P direction of the flange 1A, an operation hexagon nut portion 23 having a constant width in the axial center P direction and a subsequent round pipe portion 25 are formed. The outer diameter of the flange 1A is the same as or slightly smaller than the inner diameter of a cover rod 18 described later.

  As shown in FIGS. 2, 5, and 6, the convex portion 19 projecting in the axial center P direction from the side peripheral wall 2 a on the distal end side of the union nut 2 and projecting in the radially inward direction is similarly formed in the axial center P. The arc-shaped cover rod 18 that is cantilevered in the direction is integrally formed on the inner side of the diameter. That is, the convex portion 19 is formed in a cantilevered arm shape extending from the union nut 2 in the direction of the axis P.

  The convex portion 19 has a curved peripheral surface 19b having an arc shape when viewed in the axial center P direction, and the curvature radius of the curved peripheral surface 19b is set to be equal to or slightly smaller than the curvature radius of the concave portion 20. Both the circumferential length and the axial center P direction length of the cover rod 18 having the same outer diameter as the union nut 2 are set to be slightly longer than the corresponding length in the convex portion 19. As shown in FIGS. 2 and 10, the protruding length e of the convex portion 19 is set to be slightly longer than the axial center P direction length (thickness of the flange 1 </ b> A) f of the concave portion 20. The length of the cover rod 18 in the axial center P direction is set longer than that of the convex portion 19 by the distance g, but the same protruding length may be used.

  Next, the operation of the tightening end recognition means C will be described. When the union nut 2 screwed on the joint body 1 is turned and rotated, the tip end of the cover rod 18 covers the outside of the diameter of the flange 1A, and immediately after that the tip end surface 19a of the convex portion 19 is intermittent. It abuts on the arcuate corner of the boundary with the side peripheral surface 1b or the concave portion 20 following this with a gentle incident angle. Furthermore, when the union nut 2 is turned in the tightening direction, as shown in FIG. 8, the convex portion 19 that is cantilevered and relatively weak in supporting strength is flexed and displaced so as to turn over toward the outside of the diameter, thereby remaining. As shown in FIG. 7, the mountain portion 24 is passed over and fitted into the next recess 20 (see also FIGS. 1 and 2).

  That is, as the union nut 2 is rotated, the deflection displacement of the eight convex portions 19 to the outside of the diameter for dodging the remaining mountain portions 24 (of the convex portions 19 and the cover rod 18) (see FIG. 8), and Subsequently, the fitting of the convex portion 19 into the concave portion 20 due to the restoring displacement of the convex portion 19 (the convex portion 19 and the cover rod 18) to the inside of the diameter will be repeated thereafter. When the displacement of the convex portion 19 toward the outside of the diameter due to interference with the flange 1A starts, the state where each edge 10, 11 bites into the enlarged diameter portion 3A to some extent, that is, the assembly of the resin pipe joint A is to be completed. Tightening (screwing) by turning the union nut 2 is almost completed.

  In short, the resistance when the eight convex portions 19 (the convex portion 19 and the cover rod 18 are bent and displaced outward) becomes the strong rotational resistance of the union nut 2, and the torque fluctuation (torque increase) is hexagonal. It is clearly transmitted to the finger through a tool such as a spanner or a wrench that operates the nut portion 2b. Then, as the union nut 2 is turned in (as the amount of coverage of the convex portion 19 on the flange 1A increases), the deflection displacement of the convex portion 19 for dodging the remaining mountain portion 24 to the outside of the diameter becomes remarkable. In addition, since the torque fluctuation described above gradually increases, it is possible for the operator to know sensuously and surely that the union nut 2 has been tightened or approached.

  That is, there are a radially recessed portion 20 formed on the outer peripheral portion of the flange 1A of the joint body 1 and a radially protruding convex portion 19 formed on the outer peripheral portion of the end portion of the union nut 2 in the axial center P direction. When the seal pressing portion 10 presses against the diameter change region 9 and the union nut 2 is tightened and rotated from near the end of screwing, the concave portion 20 or the convex portion 19 is bent in the radial direction. A torque fluctuation portion 26 that is fitted and detached from each other by displacement is constituted, and the tightening end recognition means C is constituted by the presence of the torque fluctuation portion 26.

  The end of tightening (tightening) of the union nut 2 is a state in which 0.5 to 1 rotation (0.75 rotation in FIG. 9) is operated after starting to feel a clear torque fluctuation using the tool, that is, FIG. , 2 and FIG. 6, the end of the cover rod 18 and the hexagonal nut 23 side end of the flange 1 </ b> A coincide with each other in the axis P direction, that is, the tightening end state. Therefore, the tightening end recognizing means C is configured to recognize the end of tightening with a sense of operation even when the pipe joint A is not visible. In addition, it is also possible to know that the tightening is finished by viewing the state (the state shown in FIG. 6).

  The graph shown in FIG. 9 represents the fluctuation of the tightening torque accompanying the rotation of the union nut 2 in the tightening direction, and the line a drawn with a solid line is the resin pipe joint A according to the present invention (Example 1). Thus, a line b drawn with a one-dot broken line is for the first conventional product, and a line c drawn with a two-dot broken line is for the second conventional product. The first and second conventional products are pipe joints that do not have the tightening end recognition means C. The tightening rotation which is the horizontal axis is 0 in the tightening end state (see FIG. 6), and the state where the union nut 2 is loosened by one turn is represented by “−1”. Although not shown in the drawing, the rotation region on the + side exceeding 0 on the horizontal axis represents tightening.

  In the line a by the resin pipe joint A of Example 1, the first light torque increase (point p1) appears around about −0.875 rotation, which is because the tip surface 19a of the convex portion 19 is the remaining peak portion 24 (intermittently). This is considered to be caused by touching the side peripheral surface 1b) from the middle. Then, the union nut 2 is turned from the state in which each convex portion 19 first fits in the corresponding concave portion 20 (point p2), and each convex portion 19 is deflected and displaced outward in the radial direction and rides on the remaining mountain portion 24 and passes. When the first torque sudden increase (rapid tightening torque fluctuation) phenomenon (point p3) occurs, and then each projection 19 fits into the corresponding recess 20, the first tightening torque decreases rapidly. A torque sudden decrease (rapid tightening torque fluctuation) phenomenon (point p4) appears.

  In the resin pipe joint A of Example 1, since the convex part 19 in the union nut 2 is formed in eight places, it can be seen from FIG. 9 that the torque sudden increase phenomenon occurs eight times per rotation. At 0.5 rotation, the torque sudden increase phenomenon occurs four times. α = T / y (T: torque fluctuation amount, y: rotation amount of the union nut) The torque increase rate (torque fluctuation rate) α, that is, the upward inclination angle of the line a is the lines b and c, respectively. Is significantly larger than the torque increase rate. That is, the recessed part 20 and the convex part 19 are formed in multiple numbers in the circumferential direction, and it is comprised so that fitting and detachment | leave with the recessed part 20 and the convex part 19 may be repeated while the union nut 2 is rotated once.

  Due to this extremely large torque increase rate α, the operator's fingers can clearly feel the “crimping feeling” when the union nut 2 is turned, that is, the feeling corresponding to the feeling of moderation due to the detent mechanism. It can be recognized that the end of tightening is approaching. In the resin-sensed joint A according to the first embodiment, the union nut 2 may be turned when the six “crimping feeling” including the first clear “crimping feeling” is recognized, in which case the tightening end shown in FIG. This is a setting that can be obtained. In the products of the first and second conventional products represented by the lines b and c, the torque increase rate is only slightly increased or gradually increased, and a sudden torque fluctuation does not occur. The operator cannot know the end of the attachment as a finger touch.

  Next, tightening of the union nut 2 will be described. The resin pipe joint A is set so that the union nut 2 can be slightly tightened to compensate for a decrease in the holding force of the tube 3 over time. That is, in the tightened end state (see FIG. 6), there is a gap in the direction of the axis P between the side peripheral wall 2a and the flange 1A, and an additional tightening operation by further turning the union nut 2 becomes possible. ing. The tightening amount in the direction of the axis P is e + g−f.

  As shown in FIG. 10, the tightening can be performed until the side peripheral wall 2a abuts on the intermittent side peripheral surface 1b and cannot be rotated any more, that is, the final tightening state. By being in the final tightening state, there is an advantage that it is possible to prevent breakage of the pipe joint A such as screw jump of the male screw 5 and the female screw 8 and neck breakage. Furthermore, since the contact between the side peripheral wall 2a and the intermittent side peripheral surface 1b can be visually recognized from the notch space portion between the adjacent convex portions 19 and 19, it is also possible to know the final tightening state by visual observation.

[Another Example]
The torque fluctuation rate α may be caused by a sudden torque decrease, that is, by a remarkably large torque decrease rate, thereby causing a “crimp feeling” to be accompanied by a turning operation of the union nut 2. Other resin pipe joints are also possible. In addition, the present invention is applied to a joint having a structure in which a tube expanded portion is fitted in a fitting cylinder using an inner ring, that is, a resin pipe joint composed of a union nut, a joint body, and an inner ring. Also good.

  Although illustration is omitted, it is also possible to adopt a configuration in which the recess 20 formed in the joint body 1 is a recess recessed in the radially outward direction, and the protrusion 19 formed in the union nut 2 is a protrusion protruding outward in the diameter. It is. In this case, the concave portion 20 or the convex portion 19 can be deflected and displaced in the radial direction. Furthermore, in the resin pipe joint A of the first embodiment, the concave portion 20 can be configured to bend and displace in the radial direction. In addition, the number of the concave portions 20 and the convex portions 19 constituting the tightening end recognition means C may be set appropriately, such as a single or plural concave portions 20 and convex portions 19 formed in the circumferential direction. Is possible.

Sectional drawing which shows the structure of the resin pipe joint by Example 1 FIG. 1 is an enlarged sectional view showing the main part of FIG. Enlarged sectional view of the main part showing the relative positional relationship between the peripheral edges for sealing and retaining Axial direction view showing the structure of the flange part of the joint body Axial direction view showing the end structure of the union nut Plan view showing tightening end recognition means in the assembled state Partial axial view of FIG. Sectional view of the main part showing the situation where the convex part bends over the remaining mountain part Diagram showing torque change graph with union nut tightening Top view showing the final tightening state

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Joint main body 2 Union nut 3 Tube 3A Expanded diameter part 4 Fitting cylinder 5 Male thread 8 Female thread 9 Expanded diameter change area 10 Sealing pressing part 19 Convex part 20 Concave part 26 Torque fluctuation part P Shaft center S Seal part

Claims (7)

A synthetic resin joint body comprising a fitting tube that can be fitted and mounted by expanding the end of the synthetic resin tube, and a male screw, and
A union nut made of a synthetic resin provided with a female screw that can be screwed into the male screw, and a sealing pressing portion that can act on a diameter expansion change region in the diameter expansion portion of the tube;
As the union nut is screwed in the axial direction of the joint main body by screwing the female screw with the male screw in a state where the tube is fitted and attached to the fitting cylinder, the diameter expansion change region is A resin pipe joint configured to be pressed in the axial direction by a pressing portion for sealing to form a sealing portion,
A concave portion recessed in the radial direction is formed on the outer peripheral portion of the joint body, and a convex portion projecting in the radial direction is formed on the outer peripheral portion of the axial end portion of the union nut. The concave portion and the convex portion are fitted and detached from each other by a bending displacement in one of the radial directions as the union nut is tightened and rotated from near the end of screwing while pressing the diameter expansion change region. The resin pipe joint in which the torque fluctuation part is comprised.   2. The resin pipe according to claim 1, wherein a plurality of the concave portions and / or the convex portions are formed in a circumferential direction, and the fitting and the detachment are repeated while the union nut is rotated once. Fittings.   The resin pipe joint according to claim 2, wherein the concave portion and / or the convex portion are formed at equal angles with respect to the axis in the circumferential direction.   The resin pipe joint according to any one of claims 1 to 3, wherein the concave portion and / or the convex portion have an arc shape when viewed in the axial direction.   The resin according to any one of claims 1 to 4, wherein the concave portion is a radially inward concave portion that opens toward a radially outer side, and the convex portion is a radially inward convex portion that projects toward a radially inner side. Pipe fittings.   The resin pipe joint according to any one of claims 1 to 5, wherein the convex portion is formed in a cantilever arm shape extending in an axial direction from the union nut.   The resin pipe joint according to any one of claims 1 to 6, wherein the joint body and the union nut are made of a fluororesin.

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