Threaded joint

Abstract

To provide a screw-in joint capable of reliably detecting failure of insufficient crimping due to insufficient screwing with a water pressure test, the screw-in joint employing a water stop method in which a screwed-in tip is crimped to a connection target.SOLUTION: A screw-in joint comprises a cylindrical part 30 that is screwed and inserted into a valve box 71 of a valve device, and an annular crimping part 20 that is continuous with the cylindrical part 30 and is crimped to the valve box 71 when the cylindrical part 30 is inserted into the valve box 71. The cylindrical part 30 is formed with a male screw 31 on its outer peripheral surface so as to be screwed with a female screw 74 of the valve box 71. In the vicinity of the crimping part 20, a through hole 32 is formed.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a screwed joint.

Background Art

[0002] A waterstop method called metal touch, which seals water by crimping metals together, has been widely used mainly in the water supply field (Patent Documents 1 to 3). Metal touch is also used in the valve field. In a joint used for connecting a valve device and a resin pipe, the connection portion with the valve device has a structure having a flange portion and a cylindrical portion that is connected to the flange portion and has a male screw formed thereon, and water is sealed by crimping between the valve box of the metal valve device and the metal flange portion (Patent Document 4).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a screwed joint, when adopting the waterstop method by metal touch, even if the screwing is insufficient and the end of the valve box of the metal valve device and the metal flange portion are not sufficiently crimped, it may be temporarily sealed at the screwed portion where the anti-loosening adhesive is used.

[0005] Therefore, when a hydraulic pressure test was conducted during construction, temporary water stoppage occurred at the screwed-in part, and insufficient screwing-in could not be detected. As a result, there was a problem that the water stoppage performance was lost in the long term and leakage occurred after construction. In view of the above circumstances, an object of the present invention is to provide a screwed joint that adopts a water stoppage method by being crimped to a connection target, and can surely detect a defect that crimping is insufficient due to insufficient screwing by a hydraulic pressure test.

Means for Solving the Problems

[0006] In order to achieve the above object, the present invention adopts the following configuration. [1] A cylindrical portion that is screwed into a connection target and inserted, and an annular crimping portion that is continuous with the cylindrical portion and is crimped to the connection target when the cylindrical portion is inserted into the connection target. The cylindrical portion is characterized in that a male screw that engages with a female screw of the connection target is formed on an outer peripheral surface, and a through hole is formed in the vicinity of the crimping portion. [2] The screwed joint according to [1], wherein a surface of the crimping portion that is crimped to the connection target is a flat surface. [3] The screwed joint according to [1] or [2], wherein the male screw of the cylindrical portion is a parallel male screw. [4] The screwed joint according to any one of [1] to [3], wherein at least the cylindrical portion and the crimping portion are made of metal. [5] The screwed joint according to any one of [1] to [4], wherein the male screw of the cylindrical portion is formed on an outer peripheral surface on a tip side that is inserted into the connection target rather than a portion where the through hole is formed.

Effects of the Invention

[0007] The screwed joint of the present invention can surely detect a defect that crimping is insufficient due to insufficient screwing by a hydraulic pressure test.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0009] Hereinafter, a screw joint according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a state where a valve device 70 and a pipe 80 are connected to a screw joint according to an embodiment of the present invention.

[0010] The screw joint in FIG. 1 is generally composed of a joint body 10, a body 50, a retaining member 60, and a guide ring 65. Here, the joint body 10 and the body 50 are formed in a cylindrical shape, and the retaining member 60 and the guide ring 65 are formed in an annular shape.

[0011] The central axes of the joint body 10, the body 50, the retaining member 60, and the guide ring 65 are a common axis O. That is, they are arranged coaxially. The direction along the axis O is referred to as the axis O direction. The direction orthogonal to the axis O is referred to as the radial direction, and the direction of orbiting around the axis O is referred to as the circumferential direction.

[0012] The joint body 10 includes a crimping portion 20, a cylindrical tubular portion 30 continuously provided on one side of the crimping portion 20, and a cylindrical nozzle portion 40 continuously provided on the other side of the crimping portion 20. These crimping portion 20, tubular portion 30, and nozzle portion 40 are arranged coaxially with the axis O and are connected in a row along the axis O direction. Hereinafter, among the directions of the axis O, the side closer to the crimping portion 20 may be referred to as the proximal end side, and the side farther from the crimping portion 20 may be referred to as the distal end side.

[0013] The joint body 10 is formed of a metal such as brass, gunmetal, or stainless steel. The outer diameter of the crimping portion 20 is larger than the outer diameters of each of the cylindrical portion 30 and the nozzle portion 40. A step is formed on the outer peripheral surface at the boundary between the crimping portion 20 and the cylindrical portion 30. The surface along the radial direction at this step is referred to as the joint-side crimping surface 21. Also, a step is formed on the outer peripheral surface at the boundary between the crimping portion 20 and the nozzle portion 40.

[0014] FIG. 1 shows an example in which the connection target into which the cylindrical portion 30 is inserted is the valve box 71 of the valve device 70. As shown in FIG. 2, the valve box 71 has a screwing portion 72 that screws with the cylindrical portion 30 and a fitting portion 73 that fits externally onto the crimping portion 20 of the joint body 10. The screwing portion 72 and the fitting portion 73 of the valve box 71 are arranged coaxially with the axis O and are connected in a row along the direction of the axis O. An internal thread 74 is formed on the inner peripheral surface of the screwing portion 72.

[0015] The inner diameter of the portion of the screwing portion 72 where the internal thread 74 is not formed is slightly larger than the outer diameter of the cylindrical portion 30. The inner diameter of the fitting portion 73 is the same as or slightly larger than the outer diameter of the crimping portion 20. A step is formed on the inner peripheral surface at the boundary between the screwing portion 72 and the fitting portion 73. The surface along the radial direction at this step is referred to as the valve device-side crimping surface 75. The outer diameter of the screwing portion 72 gradually expands toward the fitting portion 73 so as to be continuous with the outer peripheral surface of the fitting portion 73.

[0016] An external thread 31 that screws with the internal thread 74 formed on the inner surface of the screwing portion 72 is formed on the outer peripheral surface of the cylindrical portion 30. The external thread 31 is a parallel external thread. Therefore, it can be screwed in until the joint-side crimping surface 21 of the crimping portion 20 and the valve device-side crimping surface 75 of the screwing portion 72 come into contact. Also, as shown in FIGS. 2 and 3, through holes 32 are formed at two locations in the vicinity of the crimping portion 20 of the cylindrical portion 30 so as to face each other in the radial direction with the axis O interposed therebetween.

[0017] In this embodiment, a male thread 31 is not formed on the outer peripheral surface of the portion where the through hole 32 of the cylindrical portion 30 is formed, and the male thread 31 is formed on the tip side (valve box 71 side) rather than the through hole 32. The male thread 31 may also be formed on the portion where the through hole 32 is formed. However, it is preferable to form the through hole 32 in a portion where the male thread 31 is not formed in terms of ease of processing.

[0018] The joint-side crimping surface 21 of the crimping portion 20 and the valve device-side crimping surface 75 of the screwing portion 72 face each other. When the male thread 31 and the female thread 74 are fully screwed together, the joint-side crimping surface 21 and the valve device-side crimping surface 75 are crimped to each other and are in close contact in a state where water stoppage is possible. In this embodiment, the joint-side crimping surface 21 and the valve device-side crimping surface 75 are each a flat surface, which makes it easier to crimp when pressed together.

[0019] As shown in FIG. 1, the nozzle portion 40 is composed of a nozzle base end portion 41 and a nozzle tip portion 42. The outer diameter of the nozzle tip portion 42 is smaller than the outer diameter of the nozzle base end portion 41, and a step is formed on the outer peripheral surface at the boundary between the nozzle base end portion 41 and the nozzle tip portion 42. The inner diameter of the nozzle tip portion 42 is smaller than the inner diameter of the nozzle base end portion 41, and the inner peripheral surface at the boundary between the nozzle base end portion 41 and the nozzle tip portion 42 is smoothly continuous. A plurality of circumferential grooves 43 are formed on the outer peripheral surface of the nozzle tip portion 42. The plurality of circumferential grooves 43 are formed at intervals in the direction of the axis O. A sealing material 45 such as an O-ring is disposed in the circumferential groove 43. The sealing material 45 protrudes radially outward from the circumferential groove 43.

[0020] The body 50 is disposed coaxially with the nozzle portion 40 on the radially outer side of the nozzle portion 40. There is a gap between the body 50 and the nozzle portion 40, and a cylindrical receiving portion S is formed by this gap. The body 50 includes an outer body member 51, an inner body member 52, and a lock ring 53. The outer body member 51 is formed of a transparent resin such as transparent nylon. The base end portion of the outer body member 51 is fixed to the outer peripheral surface of the nozzle base end portion 41 of the nozzle portion 40.

[0021] The inner body member 52 is accommodated in the tip side portion inside the outer body member 51. The inner body member 52 includes an annular inner body main body 52a and a plurality of striking portions 52b. Each striking portion 52b is formed in a cantilever shape and extends from the inner body main body 52a toward the base end side (the crimping portion 20 side). The plurality of striking portions 52b are arranged at intervals in the circumferential direction. At the tip end portion of each striking portion 52b, a striking convex portion 52c is provided so as to protrude radially inward. A cylindrical lock ring 53 is fitted to the base end portion of the outer body member 51.

[0022] The retaining member 60 includes an annular annular portion 61 and a retaining portion 62. The annular portion 61 is fixed by being sandwiched between the inner body member 52 and the lock ring 53. The retaining portion 62 is integrally formed on the inner peripheral edge of the annular portion 61. The retaining portion 62 is formed in a tapered shape that reduces in diameter toward the tip end side from the annular portion 61.

[0023] The guide ring 65 is disposed coaxially with the nozzle portion 40 and the body 50 between the nozzle portion 40 of the joint body 10 and the body 50. The guide ring 65 includes a movable main body portion 66 and a guide portion 67. The movable main body portion 66 is formed in an annular shape. An annular guide portion 67 is provided on the front end surface of the movable main body portion 66.

[0024] The cross-section by the plane including the axis O of the guide portion 67 is in a wedge shape. The outer peripheral surface of the guide portion 67 is formed in a tapered shape that expands in diameter toward the tip side (the side opposite to the crimping portion 20). The maximum outer diameter of the guide portion 67 is larger than the outer diameter of the movable main body portion 66. A step is formed on the outer peripheral surface at the boundary between the guide portion 67 and the movable main body portion 66. The guide ring 65 is slidable in the direction of the axis O within the receiving portion S.

[0025] The guide ring 65 and the inner body member 52 of the present embodiment are provided to generate a clicking sound when the pipe 80 is inserted to the normal position. That is, before the pipe 80 is inserted, the guide ring 65 is disposed between the tapping portion 52b and the sealing material 45. When the pipe 80 is inserted, it is pushed by the pipe 80 and slides to the position shown in FIG. 1 (the boundary position between the nozzle base end portion 41 and the nozzle tip end portion 42).

[0026] When the guide ring 65 slides, when the guide portion 67 of the guide ring 65 hits the tapping convex portion 52c and further slides, the tapping portion 52b elastically deforms so as to warp outward in the radial direction. When the pipe 80 is inserted to the normal connection position and the guide ring 65 is inserted to the position shown in FIG. 1, the tapping convex portion 52c elastically returns vigorously to the inside in the radial direction over the guide portion 67. At this time, a clicking sound is generated when the tapping convex portion 52c hits the movable main body portion 66. By hearing this, it is possible to confirm that the pipe 80 has reached the normal connection position.

[0027] According to the screw joint of the present embodiment, the reason why the defect that the crimping is insufficient due to insufficient screwing can be surely detected by the hydraulic test will be described with reference to FIGS. 4 and 5. As shown in FIG. 4, when the screwing is insufficient, a gap is generated between the joint-side crimping surface 21 and the valve device-side crimping surface 75, and a situation where water stoppage by crimping cannot be achieved occurs.

[0028] When a hydraulic pressure test is conducted in this state, a leakage path 90 occurs as shown in FIG. 5, resulting in leakage. The leakage path 90 is a path that passes from the through hole 32 through the gap between the joint-side crimping surface 21 and the valve device-side crimping surface 75, and then through the gap between the crimping portion 20 and the externally fitted portion 73. If there is no through hole 32, temporary water stoppage may be possible at the screwed portion of the male screw 31 and the female screw 74 that is secured against loosening with an adhesive. In that case, it may not be possible to detect that the state of insufficient screwing shown in FIG. 4 exists during the hydraulic pressure test because water stoppage occurs at the water stoppage location 91. However, if there is a through hole 32, leakage occurs due to the leakage path 90, so insufficient screwing can be reliably detected by the hydraulic pressure test.

[0029] <Other Embodiments> The present invention is not limited to the above-described embodiments. The connection target in the present invention is not limited to the valve box of the valve device. Also, there may be a plurality of cylindrical portions that are screwed and inserted into the connection target. That is, a screwing joint that is connected to a plurality of connection targets by screwing may also be used.

[0030] In the present invention, there is no limitation on the structure of the connection portion other than the cylindrical portion that is screwed and inserted into the connection target (in the above embodiment, the portion into which the pipe 80 is inserted). For example, it may be a female type in which the pipe is inserted inside the joint body. Also, it may be a multi-port joint into which a plurality of pipes are inserted.

[0031] Also, the surfaces where the crimping portion and the connection target are crimped are not limited to flat surfaces. For example, one may be a concave surface and the other may be a convex surface that can be in close contact with the concave surface. Also, the male screw of the cylindrical portion is not limited to a parallel male screw and may be a tapered screw. Also, there is no limitation on the material of each part of the screwing joint. For the cylindrical portion and the crimping portion, it is preferably made of metal, but there is no limitation on the material of the other parts.

[0032] Also, for the connection target, the portion that is crimped with the crimping portion is preferably made of metal, but there is no limitation on the material of the other parts. Moreover, the method for detecting insufficient screwing of the screw joint of the present invention is not limited to a hydraulic test. For example, the screwing state may be confirmed by other pressure tests such as a pneumatic test using air instead of water or a hydraulic test using oil instead of water.

Description of Signs

[0033] 10 Joint body 20 Crimping part 21 Joint-side crimping surface 30 Cylindrical part 31 Male thread 32 Through hole 40 Nozzle part 50 Body 51 Outer body member 52 Inner body member 53 Lock ring 60 Anti-disengagement member 65 Guide ring 70 Valve device 71 Valve box 72 Screwed part 73 Outer fitting part 74 Female thread 75 Valve device-side crimping surface 80 Pipe 90 Leakage path

Claims

1. a cylindrical portion that is screwed and inserted into an object to be connected; an annular crimping portion that is continuous with the cylindrical portion and is crimped to the object to be connected when the cylindrical portion is inserted into the object to be connected; the cylindrical portion is formed with a male thread that engages with a female thread of the object to be connected on an outer peripheral surface, and a through hole is formed in the vicinity of the crimping portion; The male thread of the cylindrical portion is formed on the outer peripheral surface on the tip side inserted into the object to be connected rather than the portion where the through hole is formed. A screwing joint characterized by that.

2. The screwing joint according to claim 1, wherein the surface of the crimping portion that is crimped to the object to be connected is a flat surface.

3. The screwing joint according to claim 1 or 2, wherein the male thread of the cylindrical portion is a parallel male thread.

4. The screwing joint according to any one of claims 1 to 3, wherein at least the cylindrical portion and the crimping portion are made of metal.

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