JP2020090991A - Calking nut for pipe joint - Google Patents

Abstract

To secure performance as a hose joint fitting and furthermore to suppress cracking upon calking.SOLUTION: A calking nut 16 for a pipe joint includes a nut portion 38, a cylindrical portion 40 and a projecting portion 42. The cylindrical portion 40 is coaxial with the nut portion 38, and projected from one axial end of the nut portion 38. The projecting portion 42 has an annular-shape standing from an inner circumferential surface 4002 of an end portion 4006 of the cylindrical portion 40 positioned opposite to the nut portion 38, and having an annular end face 4202 directed to a nut portion 38 direction. A distance from an end portion 4010 at a nut portion 38 side, of an outer circumferential surface 4004 of the cylindrical portion 40 to a virtual plane P orthogonal to a center axis of the inner circumferential surface 4002 through an intersection portion 4012 of the inner circumferential surface 4002 and the annular end face 4202 is a distance L. Hardness of the cylindrical portion 40 is HV 180 or more and HV 255 or less in a range over the whole length of the distance L from the end portion 4010 at the nut portion 38 side, of the outer circumferential surface 4004 of the cylindrical portion 40 and at a part of 0.5 mm from the outer circumferential surface 4004 of the cylindrical portion 40.SELECTED DRAWING: Figure 4

Description

The present invention relates to a caulking nut for pipe fittings.

Examples of the pipe joint include a hose joint fitting.
The hose joint fitting is generally configured to include a joint body and a caulking nut for a pipe joint.
The hose joint fitting is connected to a device-side joint fitting provided on the equipment through a pipe joint caulking nut.
The caulking nut for pipe fittings protrudes radially inward from the inner peripheral surface of the nut portion, the tubular portion that projects from the nut portion coaxially with the nut portion, and the end portion of the tubular portion that is located opposite to the nut portion. And an annular protrusion.
Then, by crimping the end portion of the tubular portion inward in the radial direction, the projection portion is crimped on the recessed groove formed by the side surface and the bottom surface of the joint body facing each other, and the protrusion portion is rotatable in the recessed groove. In the axial direction, the projections are movably coupled to each other within a range in which they can move between the opposing side surfaces to form a pipe joint (see Patent Document 1).

JP, 2010-266004, A

By the way, when the end portion of the tubular portion is crimped inward in the radial direction of the tubular portion, a large stress acts on the outer peripheral surface of the tubular portion.
At this time, depending on the material, the tubular portion cannot follow the deformation due to caulking, and the outer peripheral surface of the tubular portion is cracked, resulting in a defective product.
Also, depending on the material, cracking due to caulking does not occur, but the strength of the cylinder part against the pressure of the fluid flowing through the hose fitting is insufficient, so the cylinder part deforms when the fluid pressure increases, and the hose A gap is created between the joint fitting and the equipment-side joint fitting to leak fluid, which is disadvantageous in ensuring the performance as the hose fitting.
Therefore, the caulking nut for the pipe joint of the hose joint fitting has poor productivity and some improvement has been required.
The present invention has been devised in view of the above circumstances, and an object thereof is to provide a caulking nut for a pipe joint, which is advantageous in improving productivity.

In order to achieve the above-mentioned object, the present invention provides a nut portion, a tubular portion that projects from the nut portion coaxially with the nut portion, and an inner circumference of an end portion of the tubular portion that is located opposite to the nut portion. An annular projection protruding radially inward from the surface, the projection having an annular end surface standing upright from the inner peripheral surface and facing the nut portion, and the end of the tubular portion is A caulking nut for a pipe joint, which is crimped radially inward and the projection is rotatably inserted into a concave groove of the joint body to form a pipe joint, the nut part side of the outer peripheral surface of the tubular portion. When the distance L from the end of the inner peripheral surface to the imaginary plane that passes through the intersection of the inner peripheral surface and the annular end surface and is orthogonal to the central axis of the inner peripheral surface of the tubular portion on the nut portion side. The hardness of the tubular portion is HV180 or more and HV255 or less in a range from the end of the outer peripheral surface to the entire length of the distance L and at a location 0.5 mm from the outer peripheral surface of the tubular portion.

According to the present invention, by defining the hardness of the tubular portion as described above, it is advantageous in securing the strength of the tubular portion and ensuring the performance as the hose joint fitting, and also the caulking nut for the pipe joint. This is advantageous in improving productivity because cracks do not occur on the outer peripheral surface of the cylindrical portion when caulking the joint body.

It is the side view which fractured a part of hose joint metal fittings which attached the caulking nut for pipe fittings concerning an embodiment. It is the side view which fractured a part of hose joint metal fittings in which a caulking nut for pipe fittings concerning an embodiment was attached, and the equipment side joint metal fittings connected to it. It is the side view which fractured a part of hose joint metal fittings before the caulking nut for pipe fittings concerning an embodiment is attached by caulking. It is a partial expanded sectional view of a caulking nut for pipe fittings concerning an embodiment. It is a figure which shows the 1st experimental result of the caulking nut for pipe fittings. It is a figure which shows the 2nd experimental result of the caulking nut for pipe fittings.

Next, a caulking nut for pipe fittings according to an embodiment of the present invention will be described with reference to the drawings.
In the present embodiment, a case where the pipe joint is a hydraulic pipe joint (hose joint fitting) will be described.
As shown in FIG. 1, the hose fitting 10 is connected to the end of the hose 12 and is detachably connected to an appropriate device so that the fluid flowing in the hose 12 is appropriately supplied to the device or is appropriately connected to the device. The fluid is discharged through the hose 12.
The hose joint fitting 10 includes a joint body 14 and a pipe joint caulking nut 16.
The joint body 14 includes a nipple 18 and a socket 20.
As shown in FIG. 2, the hose joint fitting 10 is connected to the equipment-side joint fitting 46 provided on the equipment 44 via the pipe joint caulking nut 16.

As shown in FIG. 1, the nipple 18 is made of metal and has a tubular shape, and is configured by coaxially arranging a large diameter portion 22, a small diameter portion 24, a tool hooking portion 26, and a nipple side tubular portion 28. A hole 1802 is formed at the center of the holes 1802.
The large-diameter portion 22 is a portion that is detachably attached to and detached from the device-side joint fitting 46 and has a tubular shape.
The small diameter portion 24 is formed at the end of the large diameter portion 22 along the circumferential direction with an outer diameter smaller than that of the large diameter portion 22.
The tool hooking portion 26 is provided on the opposite side of the large diameter portion 22 with the small diameter portion 24 interposed therebetween, and has a hexagonal shape.
The caulking nut mounting concave groove 30 is formed by a side surface 2202 where the large diameter portion 22 faces the tool hanging portion 26, a bottom surface 2402 formed of the outer peripheral surface of the small diameter portion 24, and a side surface 2602 of the tool hanging portion 26 which faces the side surface 2202. Is configured.
The side surfaces 2202 and 2602 are located on a plane orthogonal to the axial center of the nipple 18, and the outer peripheral surface (bottom surface 2402) of the small diameter portion 24 is formed of a cylindrical surface with the axial center of the nipple 18 as the center.
The caulking nut 16 for pipe fitting, which will be described later, can be rotated by caulking via the caulking nut mounting concave groove 30 and moved in the axial direction within a range in which the protrusion 42 can move within the caulking nut mounting concave groove 30. Can be attached.
A concave groove 32 for mounting the socket 20 is formed in a portion of the nipple 18 adjacent to the tool hooking portion 26.
The nipple-side tubular portion 28 is provided adjacent to the concave groove 32 and is a portion to be inserted into the inner peripheral surface 1202 of the hose 12, and an uneven portion 2802 is provided on the outer peripheral surface thereof.

As shown in FIGS. 1 and 2, the socket 20 is made of metal and has a cylindrical shape.
The socket 20 is configured by coaxially arranging a tubular mounting portion 34 and a socket-side tubular portion 36.
The mounting portion 34 is attached by being caulked in the concave groove 32 of the nipple 18, whereby the nipple 18 and the socket 20 are coupled.
An annular space S is provided between the socket-side tubular portion 36 and the nipple-side tubular portion 28 in a state where the mounting portion 34 is attached to the concave groove 32.

Then, with the hose 12 inserted in the annular space S between the outer peripheral portion of the nipple 18 and the inner peripheral portion of the socket 20, a caulking range along the axial direction of the socket 20 by a caulking device (not shown). The socket 20 is crimped inwardly in the radial direction, and the hose fitting 10 is attached to the hose 12 with the entire circumference of the inner peripheral surface 1202 of the hose 12 in close contact with the entire circumference of the outer peripheral surface 2804 of the nipple-side tubular portion 28. It is attached to 12.
As shown in FIG. 2, the hose joint fitting 10 to which the pipe joint caulking nut 16 is assembled in this way is configured such that the female screw 3802 of the pipe joint caulking nut 16 is connected to the male screw of the equipment-side joint metal fitting 46 on the equipment 44 side. It is linked by binding to 4602.

Next, the caulking nut 16 for pipe fitting will be described.
As shown in FIG. 4, the caulking nut 16 for pipe fitting is configured to include a nut portion 38, a tubular portion 40, and a protruding portion 42.
The nut portion 38 has a female screw 3802 formed on the inner peripheral surface thereof and a hexagonal shape formed on the outer peripheral surface thereof.
The tubular portion 40 projects coaxially from the nut portion 38 from one end in the axial direction of the nut portion 38, and the inner peripheral surface 4002 of the tubular portion 40 is formed as a cylindrical surface.
The projecting portion 42 stands up from the inner peripheral surface 4002 of the end portion 4006 of the tubular portion 40 located opposite to the nut portion 38, presents an annular shape, and has an annular end surface 4202 facing the nut portion 38 direction.
The annular end surface 4202 is formed of an inclined surface that is displaced in a direction away from the tubular portion 40 from the inner peripheral surface 4002 toward the inner side in the radial direction. As illustrated in FIG. 1, the end portion 4006 of the tubular portion 40 is the tubular portion 40. The annular end surface 4202 and the side surface 2202 of the large-diameter portion 22 of the joint body 14 are substantially crimped inward in the radial direction of FIG. They are parallel to each other, and the annular end surface 4202 and the side surface 2202 of the large-diameter portion 22 of the joint body 14 are in surface contact with each other.
As shown in FIG. 1, in the state where the protrusion 42 is crimped, the width W1 of the protrusion 42 along the axial direction of the pipe joint caulking nut 16 is equal to the width of the caulking nut mounting groove 30. It is formed with a size smaller than W2.

Next, the fitting of the caulking nut 16 for a pipe joint to the caulking nut mounting concave groove 30 of the joint body 14 will be described.
As shown in FIG. 3, with the shaft center of the pipe joint caulking nut 16 and the shaft center of the joint body 14 aligned, the inside of the protrusion 42 and the tubular portion 40 of the pipe joint caulking nut 16 The caulking nut mounting groove 30 and the large-diameter portion 22 of the joint body 14 are inserted into the caulking nut mounting groove 16 and the joint body 14 in the axial direction of the caulking nut 16 and the joint body 14. Position it so that it is located inside.
After the positioning is completed, the end portion 4006 of the tubular portion 40 of the caulking nut 16 for pipe joint is caulked inward in the radial direction by a caulking device (not shown).
As a result, as shown in FIG. 1, the protrusion 42 of the caulking nut 16 for a pipe joint is displaced inward in the radial direction together with the end portion 4006 of the tubular portion 40, and the protrusion 42 becomes the caulking nut mounting groove 30. Be accommodated.
In this state, a gap is secured between the inner peripheral surface 4204 of the protrusion 42 and the bottom surface 2402 of the caulking nut mounting recessed groove 30, whereby the caulking nut 16 for pipe fitting is rotatable on the bottom surface 2402. It becomes a state.
Further, the protrusion 42 is in a state of being movable in the axial direction of the joint main body 14 between the both side surfaces 2202 and 2602 of the caulking nut mounting concave groove 30.

Next, as shown in FIG. 2, by connecting the female screw 3802 of the caulking nut 16 for a pipe joint to the male screw 4602 of the device side joint fitting 46, the cylinder of the device side joint fitting 46 located at the end of the male screw 4602. The end surface 4606 of the portion 4604 and the end surface 2204 of the large-diameter portion 22 of the hose fitting 10 are pressure-welded in their entire regions and are fluid-tightly coupled.

In order to improve the productivity of the caulking nut 16 for a pipe joint, the present inventor pays attention to hardness, which is one of the mechanical properties of the material forming the caulking nut 16 for a pipe joint, and particularly the tubular portion 40 in which a crack occurs. Focused on the hardness of.
That is, if the hardness of the tubular portion 40 is too low, the strength of the tubular portion 40 against the pressure of the fluid flowing through the hose fitting 10 will be insufficient. Therefore, when the pressure of the fluid becomes high, the tubular portion 40 is deformed, a gap is created between the hose joint fitting 10 and the device side joint fitting 46, and the fluid leaks, so that the performance as the hose joint fitting 10 is secured. Will be at a disadvantage.
Further, if the hardness of the tubular portion 40 is too high, when the caulking nut 16 for pipe fitting is crimped to the joint body 14, the deformation due to the caulking cannot be followed, and the outer peripheral surface 4004 of the tubular portion 40 is cracked, It becomes a defective product.
Therefore, it is necessary to set the hardness range of the tubular portion 40 of the caulking nut 16 for a pipe joint to a range that does not cause cracks during crimping while securing the strength of the tubular portion 40.

In the present embodiment, the case where the material forming the caulking nut 16 for the pipe joint is stainless steel (SUS) or carbon steel will be described. However, as the material forming the caulking nut 16 for the pipe joint, stainless steel or A metal material having the same hardness as carbon steel can be used.
As shown in FIG. 4, from the end portion 4010 of the outer peripheral surface 4004 of the tubular portion 40 on the nut portion 38 side, the intersection 4012 between the inner peripheral surface 4002 and the annular end surface 4202 is passed, and the center axis of the inner peripheral surface 4002 is orthogonal to the center axis. Let L be the distance to the virtual plane P.
The hardness of the tubular portion 40 in a range over the entire length of the distance L from the end portion 4010 on the nut portion 38 side of the outer circumferential surface 4004 of the tubular portion 40 and at a location 0.5 mm from the outer circumferential surface 4004 of the tubular portion 40 is HV180 or more HV255. The following stainless steel and carbon steel were selected.

Here, the reason for defining the range of the distance L will be described.
The reason why the end portion 4006 of the tubular portion 40 was crimped to the inside in the radial direction and cracked, and the deformation occurred during use was found to be within the range of the distance L.
Further, the reason for defining the hardness of the tubular portion 40 at a location 0.5 mm from the outer peripheral surface 4004 of the tubular portion 40 will be described.
As a result of earnest research by the present inventor, depending on the processing method of the caulking nut for a pipe joint, the hardness in the range of 0.1 mm to 0.2 mm from the surface of the outer peripheral surface 4004 of the tubular portion 40 remains in the tubular portion 40. It was found that the hardness locally increased from the hardness of the portion of No. 4 while the hardness of the portion of 0.5 mm from the outer peripheral surface 4004 of the tubular portion 40 did not locally increase due to processing.
Therefore, the hardness of the tubular portion 40 at a location 0.5 mm from the outer peripheral surface 4004 of the tubular portion 40 is defined so as not to be affected by the processing method.
Further, the hardness of the tubular portion 40 at a position 0.5 mm from the outer peripheral surface 4004 of the tubular portion 40 is measured by breaking the caulking nut for pipe fitting at a cross section including the central axis thereof, and at the fracture surface of the tubular portion 40, The hardness of 0.5 mm from the outer peripheral surface 4004 of the portion 40 is measured by a Vickers hardness meter.

More specifically, the hardness is measured at a location 0.5 mm from the outer peripheral surface 4004 of the tubular portion 40, and within a range of the entire length of the distance L from the end 4010 of the outer peripheral surface 4004 of the tubular portion 40 on the nut portion 38 side. The measurement is performed along the central axis at a pitch of a predetermined dimension, and a hardness measurement value is obtained in the range from the end portion 4010 to the entire length of the distance L.
The hardness of the tubular portion 40 in a range over the entire length of the distance L from the end portion 4010 of the outer circumferential surface 4004 of the tubular portion 40 on the nut portion 38 side and at a location 0.5 mm from the outer circumferential surface 4004 of the tubular portion 40 is HV180 or more HV255. The following is advantageous in securing the strength of the tubular portion 40 and the performance as the hose coupling fitting 10, and when the caulking nut 16 for a pipe joint is crimped to the coupling body 14, the tubular portion 40 is The outer peripheral surface 4004 is not cracked, which is advantageous in improving productivity.
If the hardness of the tubular portion 40 is less than HV180, the strength of the tubular portion 40 is reduced, which is disadvantageous in ensuring the performance of the hose joint fitting 10.
If the hardness of the tubular portion 40 exceeds HV255, when the caulking nut 16 for a pipe joint is crimped to the joint body 14, a crack is generated on the outer peripheral surface 4004 of the tubular portion 40, which is disadvantageous in improving productivity. ..

Next, an experimental example will be described.
As shown in FIGS. 5 and 6, a sample of the caulking nut 16 for a pipe joint was produced for each example, and an experiment was conducted on whether or not cracking occurred during caulking and the strength.
Two types of sample caulking nuts 16 for pipe fittings were prepared, one with a distance L of the tubular portion 40 of 50 mm and one with a distance L of the tubular portion 40 of 75 mm.
The dimensions of each part of the pipe joint caulking nut 16 used as a sample are as follows.
When the distance L of the tubular portion 40 is 50 mm, the dimensions of each part of the joint caulking nut 16 are as follows.
Inner diameter Di of cylinder 40 = 14 mm
Outer diameter Do of the tube portion 40 = 18.7 mm
Wall thickness T of the tubular portion 40 = 2.35 mm
When the distance L of the tubular portion 40 is set to 75 mm, the dimensions of each portion of the caulking nut 16 for pipe fitting are as follows.
Inner diameter Di of the cylindrical portion 40 = 21.5 mm
Outer diameter of the tubular portion 40 Do = 26.7 mm
The wall thickness T of the tubular portion 40 = 2.6 mm
The material of the caulking nut 16 for pipe fittings was stainless steel (SUS) or carbon steel.
When the material is stainless steel, the caulking nut 16 for pipe fitting is formed by cutting, and when the material is carbon steel, the caulking nut 16 for pipe fitting is formed by cold forging. When the material is carbon steel, it goes without saying that the caulking nut 16 for pipe fitting may be formed by hot forging or may be formed by cutting.

As described above, the hardness of the tubular portion 40 of the caulking nut 16 for a pipe joint is measured by measuring 0.5 mm from the outer circumferential surface 4004 of the tubular portion 40 at the outer circumferential surface 4004 of the tubular portion 40 on the nut portion 38 side. The measurement was performed at a pitch of a predetermined dimension along the central axis in the range from the end 4010 to the entire length of the distance L, and the hardness was measured in the range from the end 4010 to the entire length of the distance L.
As shown in FIG. 5, in the case of the sample in which the distance L of the tubular portion 40 was 50 mm, the pitch was 10 mm and the measurement points were 6 points A, B, C, D, E, and F.
As shown in FIG. 6, in the case of the sample in which the distance L of the tubular portion 40 was 75 mm, the pitch was 15 mm and the measurement points were 6 points A, B, C, D, E, and F.
In FIGS. 5 and 6, the measured values of hardness measured corresponding to the respective measurement points are described, and a mark ◯ is described below the measured values of hardness if the hardness is within the specified range HV180 or more and HV255 or less. However, if it is out of the range, the symbol x is described.
Further, in the column of the hardness range, if the hardness of all the measurement points A to F is within the range of the specified range HV180 or more and HV255 or less, the symbol ◯ is described, and even if there is only one measurement point of the hardness outside the above range. For example, the symbol x is described.

Next, a method for evaluating the caulking nut 16 for pipe fitting will be described.
(1) Evaluation of presence or absence of cracks due to caulking Regarding the cracks during caulking, after caulking the caulking nut 16 for pipe fitting of the sample to the joint body 14, the outer peripheral surface 4004 of the tubular portion 40 is visually inspected, The presence or absence of cracks was evaluated. In the figure, ○ indicates that there is no crack, and × indicates that there is crack.

(2) Evaluation of Strength In the present embodiment, there are two types of strength evaluation of the caulking nut 16 for a pipe joint: (A) presence or absence of deformation by a fracture test and (B) presence or absence of deformation by a torque test. An evaluation was made.
(A) Evaluation of the presence or absence of deformation by the destructive test is as follows.
The hose fitting 10 assembled to the hose is connected to the test device using the caulking nut 16 for pipe fitting, and JIS K 6330-2:2013 (Rubber and plastic hose test method-Part 2: Hose and hose assembly After performing a rupture test specified by (pressure resistance) and pressurizing the hose and the hose fitting 10 until the hose is broken, the outer peripheral surface 4004 of the tubular portion 40 is visually inspected to evaluate the presence or absence of deformation.
In the figure, ○ indicates no deformation, and × indicates deformation.

(B) Evaluation of the presence or absence of deformation by the torque test is as follows.
JIS B 8363:2015 (joint fittings and accessories for hydraulic hose assemblies), tightening torque for pipe fittings 4 times the tightening torque value of the fittings specified in Table 4 of Section 10.4 (Tightening torque test). In addition to the nut 16, the outer peripheral surface 4004 of the tubular portion 40 is visually inspected to evaluate the presence or absence of deformation.
In the figure, ○ indicates no deformation, and × indicates deformation.

As shown in Experimental Examples 1 to 4 of FIG. 5 and Experimental Examples 20 to 23 of FIG. 6, when the hardness measured in the range over the entire length of the distance L of the tubular portion 40 is less than the range of HV180 or more and HV255 or less, caulking It was found that while the evaluation of cracks by and the evaluation of deformation by the fracture test were good, the deformation by the torque test occurred and the tubular portion 40 had insufficient strength.
As shown in Experimental Examples 14 to 17 of FIG. 5 and Experimental Examples 33 to 36 of FIG. 6, when the hardness measured in the range over the entire length of the distance L of the tubular portion 40 exceeds the range of HV180 or more and HV255 or less, a destructive test. Although the evaluation of the deformation due to and the evaluation of the deformation due to the torque test were good, cracking due to caulking was observed.
As shown in Experimental Examples 5 to 13 of FIG. 5 and Experimental Examples 24 to 32 of FIG. 6, when the hardness measured over the entire length of the distance L of the tubular portion 40 is in the range of HV180 or more and HV255 or less, the caulking is performed. It was found that no cracks were observed, and the deformation evaluation by the fracture test and the deformation evaluation by the torque test were both good, and the strength of the tubular portion 40 was secured.

In addition, although the case where the pipe body is the hose 12 and the pipe joint is the hose joint fitting 10 has been described in the present embodiment, the present invention is widely applicable to a pipe joint that connects steel pipes and the like.

10 Hose fittings (pipe fittings)
14 joint body 16 caulking nut for pipe joint 18 nipple 20 socket 22 large diameter portion 2202 side surface 2402 bottom surface 2602 side surface 26 tool hook 30 caulking nut mounting concave groove 38 nut portion 40 tubular portion 4002 inner peripheral surface 4010 end portion 4012 Intersection 42 Projection L Distance P Virtual plane

Claims (2)

A nut portion, a tubular portion that projects from the nut portion coaxially with the nut portion, and an annular protrusion that projects radially inward from the inner peripheral surface of the end portion of the tubular portion that is located opposite to the nut portion. With and
The protruding portion has an annular end surface that stands up from the inner peripheral surface and faces the nut portion, and the end portion of the tubular portion is caulked inward in the radial direction, and the protruding portion is formed in the groove of the joint body. Is a caulking nut for a pipe joint, which is rotatably inserted to form a pipe joint,
A distance L is defined as a distance from an end portion of the outer peripheral surface of the cylindrical portion on the nut portion side to a virtual plane that passes through an intersection of the inner peripheral surface and the annular end surface and is orthogonal to a central axis of the inner peripheral surface. Then, the hardness of the tubular portion is HV180 or more and HV255 in a range over the entire length of the distance L from the end portion of the outer circumferential surface of the tubular portion on the nut portion side and at a location 0.5 mm from the outer circumferential surface of the tubular portion. Is less than
A caulking nut for pipe fittings characterized in that The caulking nut for the pipe joint is used for a hydraulic pipe joint,
The swaging nut for a pipe joint according to claim 1.

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