JP2018025278A - Pipe joint connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the torque resistance rigidity of a male-side pipe joint while suppressing the narrowing of a flow passage caused by the deformation of a cylinder part which is arranged inside a female-side pipe joint.SOLUTION: A pipe joint connection structure S has: a female-side pipe joint 10 which is formed into a tubular shape, has a female screw 14A at an end part, and has a cylinder part 16A apart from the female screw 14A in a radial direction on the same axis of the female screw 14A at the inside of the radial direction; and a male-side pipe joint 12 having, at an internal peripheral side, an extension face 22 in an axial core direction in which a male screw 20 screwed with the female screw 14A is arranged at one end side in an axial line direction L, which extends to the other end side from one end side in the axial line direction L, and in which an external peripheral face of the cylinder part 16A is overlapped on the extension face in a fastened state of the male screw 20 with respect to the female screw 14A, and a diameter-contracted face 24 which is formed succeeding to the extension face 22 in the axial core direction, and contracted in a diameter as progressing toward the other end side in the axial core direction L.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pipe joint connection structure.

  Patent Document 1 discloses an example of an anticorrosion pipe joint. In this anticorrosion pipe joint, a cylindrical part extending from the synthetic resin layer is coated with a synthetic resin layer on the inner peripheral surface of a metal joint (female side pipe joint) having an internal thread at the end, and the portion excluding the female thread is covered with the synthetic resin layer. Is provided on the opening side of the metal joint. A gap having a predetermined width is provided between the female thread of the metal joint and the cylindrical portion made of synthetic resin. The end portion of the lining metal pipe connected to the anticorrosion pipe joint is inserted into this gap.

Japanese Patent Laid-Open No. 7-139668

  However, when connecting a pipe joint (male side pipe joint) provided with a male thread at the end to the above-described metal joint (female side pipe joint), the wall thickness of the end is the same as that of the female thread in the metal joint. If the gap is larger than the gap between the two parts, it is considered that the cylindrical part falls inward in the radial direction of the metal joint and the flow path is narrowed. On the other hand, if the thickness of the end of the pipe joint is reduced, it may be difficult to ensure the strength.

  An object of the present invention is to improve torque resistance strength of a male side pipe joint while suppressing narrowing of a flow path due to deformation of a cylindrical portion provided inside the female side pipe joint.

  The first aspect of the present invention (pipe joint connection structure) is formed in a tubular shape, and is provided with a female screw at an end, and a cylindrical portion radially spaced from the female screw is coaxially arranged on the radially inner side of the female screw. A female-side pipe joint provided and a male screw threadedly engaged with the female screw is provided on one end side in the axial direction, and extends from one end side to the other end side in the axial direction in the tightened state of the male screw with respect to the female screw. An axially extending surface in which the outer peripheral surface of the cylindrical portion overlaps in the radial direction, and a reduced diameter surface that is formed following the axially extending surface and decreases in diameter toward the other end side in the axial direction. And a male pipe joint provided on the inner periphery.

  In this pipe joint connection structure, when connecting the male side pipe joint to the female side pipe joint, the female thread of the female side pipe joint and the male thread of the male side pipe joint are screwed together, and the male screw is tightened with respect to the female thread. Thereby, one end of the male side pipe joint in the axial center direction is fitted between the female thread and the resin-made cylindrical part in the female side pipe joint. At this time, the axially extending surface extending from one end side in the axial direction to the other end side in the inner periphery of the male pipe joint overlaps with the outer peripheral surface of the cylindrical part in the radial direction. Power does not work. For this reason, it is suppressed that a cylindrical part falls down toward the radial inside of a female side pipe joint.

  In addition, on the inner periphery of the male side pipe joint following the axially extending surface, a reduced diameter surface is provided that decreases in diameter toward the other end side in the axial direction. Thereby, the thickness between an inner periphery and an outer periphery is ensured in the site | part of the other end side of an axial direction from the axial direction extension surface. For this reason, the torque resistance strength of the male side pipe joint can be improved.

  According to a second aspect, in the pipe joint connection structure according to the first aspect, a joint body portion is provided on the other end side of the male screw in the axial direction, and the joint body portion includes the male screw with respect to the female screw. A torque input portion for inputting torque to the male side pipe joint at the time of tightening is formed, and the boundary between the torque input portion and the male screw overlaps the reduced diameter surface in the radial direction.

  In this pipe joint connection structure, the boundary between the torque input portion and the male screw in the male side pipe joint and the reduced diameter surface overlap in the radial direction. Therefore, stress concentration at the boundary between the torque input portion and the male screw is suppressed. For this reason, the torque resistance strength of the male side pipe joint can be further improved.

  According to a third aspect, in the pipe joint connection structure according to the first aspect or the second aspect, the male side pipe joint is configured using a resin material.

  In this pipe joint connection structure, since the male side pipe joint is configured using a resin material, the weight can be reduced.

  According to the pipe joint connection structure according to the present invention, it is possible to improve the torque resistance strength of the male pipe joint while suppressing the narrowing of the flow path due to the deformation of the cylindrical portion provided inside the female pipe joint. it can.

It is sectional drawing which shows the male side pipe joint which concerns on this embodiment. It is sectional drawing which shows the male side pipe joint and female side pipe joint which concern on this embodiment. It is sectional drawing which shows the state in which the male side pipe joint and the female side pipe joint were connected.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In FIG. 2, the pipe joint connection structure S according to the present embodiment includes a female side pipe joint 10 and a male side pipe joint 12.

  In FIG. 2, the female side pipe joint 10 is formed in, for example, a straight tubular shape, and a female screw 14 </ b> A is provided at one end 10 </ b> A in the axial direction L. A female screw 10B is provided at the other end 10B. The female screws 14A and 14B are a pipe taper screw or a pipe parallel screw. For example, a metal tube 18 is connected to the female screw 10B. A coaxial cylindrical portion 16A made of, for example, resin and spaced radially from the female screw 14A is provided coaxially on the radially inner side of the female screw 14A. A resin-made cylindrical portion 16B spaced from the female screw 14B is also provided coaxially on the radially inner side of the female screw 14B.

  The cylindrical portions 16 </ b> A and 16 </ b> B are part of a resin core 16 provided in a region where the female screws 10 </ b> A and 10 </ b> B are not provided on the inner periphery of the female side pipe joint 10. The cylindrical portions 16A and 16B are formed so as to protrude from both ends of the core 16 in the axial direction L, respectively, and a part of the inner side of the female screws 14A and 14B (the central side in the axial direction L of the female side pipe joint 10). Overlapping in the radial direction. A seal member (not shown) may be provided on the outer periphery of the cylindrical portions 16A and 16B.

  The male side pipe joint 12 is configured in a straight shape using, for example, a resin material, and a male screw 20 that is screwed with the female screw 14A is provided on one end side in the axial direction L. The male screw 20 is a pipe taper screw. An axially extending surface 22 and a reduced diameter surface 24 are provided on the inner periphery of the male side pipe joint 12.

  The axially extending surface 22 extends from one end side in the axial direction L to the other end side. As shown in FIG. 3, the axially extending surface 22 is a portion where the outer peripheral surface of the cylindrical portion 16 </ b> A overlaps in the radial direction when the male screw 20 is tightened with respect to the female screw 14 </ b> A. The diameter-reduced surface 24 is formed following the axially extending surface 22 and is reduced in diameter toward the other end side in the axial direction L. The reduced diameter surface 24 is, for example, a conical tapered surface. The diameter-reduced surface 24 is not limited to a tapered surface, and may have an arbitrary cross-sectional shape such as a cross-sectional arc-shaped surface, a cross-sectional broken line shape, or a combination of a straight line and an arc.

  The inner diameter of the axially extending surface 22 is set to be equal to or slightly smaller than the outer diameter of the cylindrical portion 16A. This is to ensure water tightness between the axially extending surface 22 and the cylindrical portion 16A. As shown in FIG. 2, the length L1 of the axially extending surface 22 is the length of the cylindrical portion 16A so that the cylindrical portion 16A does not interfere with the reduced diameter surface 24 when the male screw 20 is tightened with respect to the female screw 14A. It is set slightly longer than the length L2.

  A joint main body portion 26 is provided on the other end side of the male screw 20 in the axial direction L. The joint body 26 is formed with a torque input portion 28 for inputting torque to the male side pipe joint 12 when the male screw 20 is fastened to the female screw 14A. The boundary 30 between the torque input portion 28 and the male screw 20 and the reduced diameter surface 24 overlap in the radial direction. The diameter-reduced surface 24 is reduced in diameter toward the other end side in the axial direction L, and the boundary 30 overlaps the diameter-reduced surface 24 in the radial direction. More than the thickness t at the position of the axially extending surface 22 is secured. Specifically, T / t = 1.2 to 3.0.

  The torque input part 28 is the thickest part in the joint main body part 26, and is formed in, for example, a hexagon. As shown in FIG. 1, a concave portion 32 that is recessed in the radial direction of the joint main body portion 26 is provided on the outer periphery of the torque input portion 28. The concave portion 32 is a long groove in which the circumferential direction of the torque input portion 28 is a longitudinal direction and the axial direction L of the joint body portion 26 is a short direction. When torque is input to the torque input unit 28 by a tool, the corners of the torque input unit 28 are crushed by the tool before the male pipe joint 12 is cracked. The torque input unit 28 may be formed in another polygonal shape or may be two surfaces parallel to each other.

  In the axial direction L of the male side pipe joint 12, a pipe connecting part 34 is provided on the opposite side of the joint main body part 26 from the male screw 20. The structure of the tube connection part 34 is, for example, a cylindrical part 36, a positioning part 38, and an insertion part 40. The insertion part 40 is a cylindrical part into which another tube (not shown) is inserted. Two groove portions 42 are provided on the outer periphery of the insertion portion 40. An O-ring 44 is provided in each of the groove portions 42.

  A tubular intermediate portion 46 that is extrapolated to the joint main body portion 26 and a sleeve 48 that is extrapolated to the intermediate portion 46 are provided. Inside the sleeve 48, a lock ring 50 is disposed as a holding portion for holding another tube inserted into the tube connecting portion 34. The lock ring 50 is formed in a ring shape and has a substantially V shape with a cross section rotated by 90 degrees. The lock ring 50 is disposed so that the substantially V-shaped opening is directed to the back side of the joint body 26 (the side opposite to the insertion side of the other tubular body). The opening of the lock ring 50 faces the tip 46A of the intermediate portion 46, and a part of the substantially V-shaped inner surface is in contact with the tip 46A.

  A claw portion 52 is formed at the V-shaped tip disposed on the radially inner side of the lock ring 50. The nail | claw part 52 is bent and extended in the direction which goes to the outer side of V shape from the direction along V shape seeing from the circumferential direction. The tip of the claw 52 is pointed and has a shape that can easily bite into other tubular bodies.

  The lock ring 50 can be elastically deformed so that the inner space of the V-shape is collapsed, in other words, the portions extending on both sides of the V-shape approach each other. Therefore, the lock ring 50 can be elastically deformed and expanded concentrically with the insertion of the tubular body into the tubular body connecting portion 34.

  A tapered surface 48 </ b> A with which the substantially V-shaped outer surface of the lock ring 50 can abut is formed on the inner wall of the sleeve 48. A release ring 54 that is movable along the axial direction of the male side pipe joint 12 is inserted on the inner peripheral side of the sleeve 48 and on the distal end side of the tube connecting portion 34 with respect to the lock ring 50. The release ring 54 has a substantially cylindrical shape. A protrusion 54A is formed on the outer circumference of the sleeve 48 of the release ring 54 in the circumferential direction, and comes into contact with a small diameter portion 48B formed on the inner circumference of the sleeve 48, so that the release ring 54 is separated from the sleeve 48. Omission is prevented. The tip 54B of the protrusion 54A has a tapered shape that is tapered, and is disposed along the radially outer peripheral surface of the lock ring 50.

  The positioning portion 38 of the tube connecting portion 34 is formed on the back side with respect to the groove portion 42. When the other tubular body is inserted into the tubular body connecting portion 34, the distal end of the tubular body abuts against the positioning portion 38, so that insertion of further tubular bodies is restricted. That is, the positioning portion 38 serves as a stopper that limits the insertion depth of other tubular bodies.

  The reduced diameter surface 24 terminates at, for example, the position of the cylindrical portion 36 of the tube connecting portion 34, and the inner periphery on the other end side in the axial direction (the distal end side of the tube connecting portion 34) extends from the reduced diameter surface 24. An axially extending surface 56 having the same inner diameter as the minimum inner diameter and an expanded diameter surface 58 continue. The diameter-enlarging surface 58 is a conical tapered surface that increases in diameter toward the tip of the tube connecting portion 34.

  In addition, the structure of parts other than the male screw 20 and the joint main-body part 26 in the male side pipe joint 12 is arbitrary.

(Function)
This embodiment is configured as described above, and the operation thereof will be described below. 3, in the pipe joint connection structure S according to the present embodiment, when the male pipe joint 12 is connected to the female pipe joint 10, the female thread 14A of the female pipe joint 10 and the male thread 20 of the male pipe joint 12 are And the male screw 20 is fastened to the female screw 14A. Thereby, one end of the male side pipe joint 12 in the axial direction L is fitted between the female screw 14A in the female side pipe joint 10 and the resin cylindrical part 16A, and the cylindrical part 16A extends in the axial direction. The surface 22 is in close contact with the surface 22.

  At this time, the axially extending surface 22 extending from one end side in the axial direction L to the other end side in the inner periphery of the male side pipe joint 12 overlaps with the outer peripheral surface of the cylindrical portion 16A in the radial direction. An excessive force does not act on the shape portion 16A. Also, as shown in FIG. 2, the length L1 of the axially extending surface 22 is set slightly longer than the length L2 of the cylindrical portion 16A, so that when the male screw 20 is tightened with respect to the female screw 14A, the cylinder The shaped portion 16 </ b> A does not interfere with the reduced diameter surface 24. For this reason, it is suppressed that 16 A of cylindrical parts fall down toward the radial direction inner side of the female side pipe joint 10. FIG. Moreover, since the watertightness between the female side pipe joint 10 and the male side pipe joint 12 is ensured by this, corrosion resistance improves.

  Further, on the inner circumference of the male side pipe joint 12 following the axially extending surface 22, a reduced diameter surface 24 is provided that decreases in diameter toward the other end side in the axial direction L. Thereby, the thickness of the site | part of the other end side of the axial direction L from the axial direction extending surface 22 is ensured. Specifically, since the boundary 30 between the torque input portion 28 and the male screw 20 and the reduced diameter surface 24 overlap in the radial direction, the inner periphery and the outer periphery at the boundary 30 between the torque input portion 28 and the male screw 20. Is more than the thickness t at the position of the axially extending surface 22. Therefore, stress concentration at the boundary between the torque input unit 28 and the male screw 20 is suppressed. For this reason, the torque resistance strength of the male side pipe joint 12 can be improved.

  Thus, according to the pipe joint connection structure S, the torque resistance strength of the male side pipe joint 12 is increased while suppressing the narrowing of the flow path due to the deformation of the cylindrical portion 16A provided inside the female side pipe joint 10. Can be improved.

  Furthermore, since the male side pipe joint 12 is comprised using a resin material, weight reduction can be achieved. Since the recess 32 (FIG. 1) is provided on the outer periphery of the torque input portion 28, if an excessive torque is input to the torque input portion 28 by a tool, before the male side pipe joint 12 is cracked. The corners of the torque input unit 28 are crushed by a tool. For this reason, even if the male side pipe joint 12 is comprised using the resin material, crack generation | occurrence | production can be suppressed. Furthermore, since excessive torque input to the male side pipe joint 12 is suppressed, the narrowing of the flow path due to tightening of the pipe taper screw is also suppressed.

[Other Embodiments]
As mentioned above, although an example of embodiment of this invention was demonstrated, embodiment of this invention is not limited above, In addition to the above, in a range which does not deviate from the main point, it can implement variously. Of course there is.

  Although the torque input part 28 is provided in the male side pipe joint 12, the structure in which the torque input part 28 is not provided may be sufficient. Moreover, although the male side pipe joint 12 shall be comprised using the resin material, you may be comprised using the metal material.

  The female side pipe joint 10 and the male side pipe joint 12 are assumed to be straight types, but can be applied to pipe joints of various shapes such as elbow type and cheese type.

(Test example)
A comparative example in which the reduced diameter surface 24 is not provided on the male pipe joint 12 and the thickness T at the position of the boundary 30 is the same as the thickness t at the axially extending surface 22 is compared with the present embodiment. With respect to the male side pipe joint 12, the breaking torque at the time of connection to the female side pipe joint (when the male screw was tightened with respect to the female thread) was measured. Evaluation is based on the maximum torque when a crack occurs.

  When tightened along the axial direction L, this embodiment improved about 21% compared to the comparative example. Further, when the male screw was tilted with respect to the female screw and tightened, the improvement was about 23%. Furthermore, when tightened while applying a bending stress, it was improved by about 20%. From these results, it was found that when the reduced diameter surface 24 is provided to ensure the thickness, the torque resistance strength is improved.

DESCRIPTION OF SYMBOLS 10 ... Female side pipe joint, 12 ... Male side pipe joint, 14A ... Female thread, 16A ... Cylindrical part, 20 ... Male screw, 22 ... Axis direction extended surface, 24 ... Reduced diameter surface, 26 ... Joint main-body part, 28 ... Torque input part, 30 ... Boundary, L ... Axial direction, S ... Fitting connection structure

Claims (3)

A female side pipe joint formed in a tubular shape, provided with a female thread at the end, and provided with a cylindrical part coaxially spaced radially from the female thread on the radially inner side of the female thread;
A male screw that engages with the female screw is provided on one end side in the axial direction, and extends from one end side to the other end side in the axial direction, and the outer peripheral surface of the cylindrical portion is in the radial direction in the tightened state of the male screw with respect to the female screw. And an axially extending surface that overlaps with the axially extending surface and a reduced diameter surface that is formed following the axially extending surface and decreases in diameter toward the other end in the axial direction. Side fittings,
A pipe joint connection structure. A joint main body is provided on the other end side in the axial direction of the male screw,
The joint body portion is formed with a torque input portion for inputting torque to the male pipe joint when the male screw is tightened with respect to the female screw,
The pipe joint connection structure according to claim 1, wherein a boundary between the torque input portion and the male screw and the reduced diameter surface overlap in a radial direction.   The pipe joint connection structure according to claim 1, wherein the male side pipe joint is configured using a resin material.

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