JP7709348B2 - Threaded Fittings - Google Patents

Description

The present invention relates to a threaded joint.

A water-stopping method called "metal touch," which stops water by crimping metal to metal, has been widely used mainly in the water supply industry (Patent Documents 1 to 3).
Metal touch is also used in the field of valves. In a joint used to connect a valve device to a plastic pipe, the connection part with the valve device has a structure having a flange part and a cylindrical part connected to the flange part and having a male thread, and water is stopped by crimping the metal valve body of the valve device to the metal flange part (Patent Document 4).

Patent No. 4157493 JP 2008-303894 A Patent No. 3871428 Patent No. 4719176

However, when using a metal-to-metal watertight method for threaded joints, even if the threads are not fully threaded and the end of the metal valve body of the metal valve device and the metal flange are not fully crimped, the threaded part, which uses an adhesive to prevent loosening, may temporarily watertight.

As a result, when a water pressure test was conducted during construction, the screwed parts would temporarily stop water flowing, and the insufficient screwing would go unnoticed. Over the long term, the watertightness would disappear and water would leak after construction.
In view of the above circumstances, an object of the present invention is to provide a threaded joint that employs a water-stopping method in which the joint is crimped to the object to be connected, and in which defects such as insufficient crimping due to insufficient threading can be reliably detected by a water pressure test.

In order to achieve the above object, the present invention employs the following configuration.
[1] A cylindrical portion that is screwed into and inserted into a connection target;
a ring-shaped crimping portion that is continuous with the cylindrical portion and that is crimped to the connection target when the cylindrical portion is inserted into the connection target,
A threaded joint, characterized in that the tubular portion has a male thread formed on its outer surface that screws into the female thread of the connection object, and a through hole formed in the vicinity of the crimp portion.
[2] A threaded joint as described in [1], wherein the surface of the crimping portion that is crimped to the connection object is a flat surface.
[3] A threaded joint as described in [1] or [2], wherein the male thread of the tubular portion is a parallel male thread.
[4] A threaded joint according to any one of [1] to [3], wherein at least the tubular portion and the crimping portion are made of metal.
[5] A threaded joint described in any one of [1] to [4], wherein the male thread of the tubular portion is formed on the outer peripheral surface on the tip side that is inserted into the connection object, rather than the portion where the through hole is formed.

The threaded joint of the present invention can reliably detect defects caused by insufficient threading and insufficient crimping through a water pressure test.

1 is a partially cutaway cross-sectional view showing a state in which a valve device and a pipe are connected to a threaded joint according to an embodiment of the present invention. FIG. 4 is a cross-sectional view showing a connection portion between a screw joint and a valve device when screwing is sufficient. 4 is a cross-sectional view of the cylindrical portion at a location where a through hole is formed. FIG. 11 is a cross-sectional view showing a connection portion between a screw joint and a valve device when the screwing is insufficient. FIG. 13 is a diagram illustrating a leakage path when the screwing is insufficient. FIG.

Below, a threaded joint according to an embodiment of the present invention will be described with reference to the drawings. Figure 1 shows a schematic diagram of a threaded joint according to one embodiment of the present invention, in which a valve device 70 and a pipe 80 are connected.

The threaded joint in FIG. 1 is generally composed of a joint main body 10, a body 50, a retaining member 60, and a guide ring 65.
Here, the joint main 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.

The central axes of the joint main body 10, the body 50, the retaining member 60, and the guide ring 65 are a common axis O. In other words, they are arranged coaxially. The direction along the axis O is called the axis O direction. The direction perpendicular to the axis O is called the radial direction, and the direction going around the axis O is called the circumferential direction.

The joint body 10 includes a crimping portion 20, a cylindrical tubular portion 30 connected to one end of the crimping portion 20, and a cylindrical nozzle portion 40 connected to the other end of the crimping portion 20. The crimping portion 20, the tubular portion 30, and the nozzle portion 40 are arranged coaxially with the axis O and are aligned in a row along the direction of the axis O.
Hereinafter, in the direction of axis O, the side closer to the crimping portion 20 may be referred to as the base end side, and the side farther from the crimping portion 20 may be referred to as the tip end side.

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

FIG. 1 shows an example in which the connection target into which the tubular portion 30 is inserted is a valve box 71 of a valve device 70 .
2, the valve box 71 has a threaded portion 72 that threadably engages with the cylindrical portion 30, and an outer fitting portion 73 that fits onto the crimp portion 20 of the joint body 10. The threaded portion 72 and the outer fitting portion 73 of the valve box 71 are disposed coaxially with the axis O and are connected in a row along the direction of the axis O. A female thread 74 is formed on the inner peripheral surface of the threaded portion 72.

The inner diameter of the portion of the screw-fitting portion 72 where the female thread 74 is not formed is slightly larger than the outer diameter of the tubular portion 30. The inner diameter of the outer 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 circumferential surface at the boundary between the screw-fitting portion 72 and the outer fitting portion 73. The surface of this step that runs along the radial direction is referred to as the valve device side crimping surface 75.
The outer diameter of the screw portion 72 gradually increases toward the outer fitting portion 73 so as to be continuous with the outer peripheral surface of the outer fitting portion 73 .

The outer peripheral surface of the cylindrical portion 30 is formed with a male thread 31 that screws into a female thread 74 formed on the inner surface of the screw-on portion 72. The male thread 31 is a parallel male 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 screw-on portion 72 come into contact. In addition, as shown in Figures 2 and 3, two through holes 32 are formed in the vicinity of the crimping portion 20 of the cylindrical portion 30 at two locations that face each other in the radial direction across the axis O.

In this embodiment, the male thread 31 is not formed on the outer peripheral surface of the portion of the cylindrical portion 30 where the through hole 32 is formed, but is formed on the tip side (valve box 71 side) of the through hole 32. The male thread 31 may also be formed in the portion where the through hole 32 is formed. However, it is preferable to form the through hole 32 in the portion where the male thread 31 is not formed, as this makes processing easier.

The joint-side crimping surface 21 of the crimping portion 20 and the valve device-side crimping surface 75 of the screw portion 72 face each other.
The joint-side crimping surface 21 and the valve device-side crimping surface 75 are crimped to each other and come into close contact in a watertight state when the male thread 31 and the female thread 74 are fully screwed together.
In this embodiment, the joint-side crimping surface 21 and the valve device-side crimping surface 75 are each flat, making them easier to crimp when pressed together.

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 circumferential 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 circumferential 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 circumferential surface of the nozzle tip portion 42. The plurality of circumferential grooves 43 are formed at intervals from one another in the direction of the axis O. A seal material 45 such as an O-ring is disposed in the circumferential groove 43. The seal material 45 protrudes radially outward from the circumferential groove 43.

The body 50 is disposed radially outside the nozzle portion 40 and coaxially with the nozzle portion 40. A gap is provided 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. A base end of the outer body member 51 is fixed to an outer peripheral surface of the nozzle base end 41 of the nozzle portion 40.

The inner body member 52 is housed 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 tapping portions 52b. Each tapping 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 tapping portions 52b are arranged at intervals from each other in the circumferential direction. A tapping protrusion 52c is provided at the tip of each tapping portion 52b so as to protrude radially inward.
A cylindrical lock ring 53 is fitted onto the base end of the outer body member 51 .

The retaining member 60 includes an 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 formed integrally with the inner peripheral edge of the annular portion 61. The retaining portion 62 is formed in a tapered shape that decreases in diameter from the annular portion 61 toward the tip side.

The guide ring 65 is disposed between the nozzle portion 40 and the body 50 of the joint body 10, and is coaxial with the nozzle portion 40 and the body 50. The guide ring 65 includes a movable body portion 66 and a guide portion 67. The movable body portion 66 is formed in an annular shape. The annular guide portion 67 is provided on the tip surface of the movable body portion 66.

The cross section of the guide portion 67 taken along a plane including the axis O is wedge-shaped. The outer peripheral surface of the guide portion 67 is tapered so that the diameter increases toward the tip side (the side opposite 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 receiving portion S in the direction of the axis O.

The guide ring 65 and the inner body member 52 in this embodiment are provided to generate a clicking sound when the piping 80 is inserted to the correct position.
That is, before the piping 80 is inserted, the guide ring 65 is disposed between the striking portion 52b and the seal material 45. Then, when the piping 80 is inserted, the guide ring 65 is pushed by the piping 80 and slides to the position shown in Fig. 1 (the boundary position between the nozzle base end portion 41 and the nozzle tip portion 42).

When the guide ring 65 slides, the guide portion 67 of the guide ring 65 comes into contact with the striking protrusion 52c, and the guide ring 65 slides further, causing the striking portion 52b to elastically deform so as to bend radially outward. Then, when the piping 80 is inserted to the correct connection position and the guide ring 65 is inserted to the position shown in FIG. 1, the striking protrusion 52c overcomes the guide portion 67 and elastically returns vigorously to the radially inward direction. At this time, the striking protrusion 52c strikes the movable main body portion 66, generating a clicking sound. By listening to this, it can be confirmed that the piping 80 has reached the correct connection position.

The reason why the threaded joint of this embodiment can reliably detect defects such as insufficient threading and insufficient crimping by a water pressure test will be described with reference to Figs. 4 and 5.
As shown in FIG. 4, if the screwing is insufficient, a gap will be generated between the joint-side crimping surface 21 and the valve device-side crimping surface 75, making it impossible to achieve watertightness through crimping.

When a water pressure test is performed in this state, a water leakage path 90 occurs and water leaks, as shown in Fig. 5. The water 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 outer fitting portion 73.
If the through hole 32 were not present, temporary water blocking might be possible at the screwed portion between the male thread 31 and the female thread 74, which are secured against loosening by an adhesive. In that case, water would be blocked at the water blocking portion 91, and it might not be possible to detect the insufficient screwing state shown in FIG. 4 during a water pressure test.
However, if the through hole 32 is present, water leakage will occur through the leakage path 90, so that insufficient screwing can be reliably detected by a water pressure test.

<Other embodiments>
The present invention is not limited to the above-described embodiments.
The connection object in the present invention is not limited to the valve body of the valve device. In addition, there may be a plurality of tubular parts that are screwed into and inserted into the connection object. In other words, the connection object may be a threaded joint that is connected to a plurality of connection objects by screwing.

In the present invention, there is no limitation on the structure of the connection part (in the above embodiment, the part into which the piping 80 is inserted) other than the cylindrical part that is screwed into the connection target. For example, the connection part may be a female type in which the piping is inserted inside the fitting body. It may also be a multi-port fitting into which multiple pipes are inserted.

Furthermore, the surfaces on which the crimping portion and the connection object are crimped are not limited to flat surfaces, and may be, for example, a concave surface on one side and a convex surface on the other side that can come into close contact with the concave surface.
Furthermore, the male thread of the cylindrical portion is not limited to a parallel male thread, but may be a tapered thread.
There is also no limitation on the material of each part of the threaded joint. The cylindrical part and the crimping part are preferably made of metal, but there is no limitation on the material of the other parts.

Furthermore, the portion of the connection object that is crimped to the crimping portion is preferably made of metal, but there is no limitation on the material of the other portions.
Furthermore, the method of detecting insufficient threading of a threaded joint of the present invention is not limited to a water pressure test. For example, the threaded 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.

Reference Signs List 10: joint body 20: crimping portion 21: joint-side crimping surface 30: cylindrical portion 31: male thread 32: through hole 40: nozzle portion 50: body 51: outer body member 52: inner body member 53: lock ring 60: retaining member 65: guide ring 70: valve device 71: valve box 72: screw-fitting portion 73: outer fitting portion 74: female thread 75: valve device-side crimping surface 80: piping 90: water leakage path

Claims (4)

A cylindrical portion that is screwed into and inserted into a connection target;
a ring-shaped 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 has an outer circumferential surface formed with a male thread that screws into the female thread of the connection target, and a through hole formed in the vicinity of the crimping portion ,
A threaded joint, characterized in that the male threads of the tubular portion are formed on the outer peripheral surface of the tip side that is inserted into the connection object, rather than the portion where the through hole is formed . The threaded joint according to claim 1, wherein the surface of the crimping portion that is crimped to the connection object is flat. A threaded joint according to claim 1 or 2, wherein the male thread of the cylindrical portion is a parallel male thread. A threaded joint according to any one of claims 1 to 3, in which at least the tubular portion and the crimping portion are made of metal.