JPH11325360A - Pipe joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a second pipe from pulling out to prevent cutting caused by a pulling stress of the second pipe, by caulking a connecting pipe at its two positions, which connects a first pipe to the second pipe in an axially longitudinal direction. SOLUTION: A second pipe 2 is fitted onto a periphery of a first pipe 1. A connecting pipe 3 is fitted onto an outer periphery of the second pipe 2, and is caulked its plural portions by caulking parts 4a, 4b in an axially longitudinal direction thereof. A thickness of the connection pipe 3 is gradually reduced from one end to the other end. A caulking rate of the thinner caulking part 4a is made smaller than that of the thicker caulking part 4b, so that the caulking part 4b having the larger caulking rate prevents the second pipe 2 from pulling out, and thereby the caulking part 4a having the small caulking rate prevents cutting caused by a pulling stress of the second pipe 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe joint used for connecting elastic pipes for supplying and discharging pressure oil in various hydraulic circuits, for example.

[0002]

2. Description of the Related Art In various hydraulic drive devices widely used in many industrial fields in order to perform a predetermined operation by the operation of a hydraulic actuator, supply and discharge of hydraulic oil to and from the hydraulic actuator are performed. In many cases, an elastic pipe such as a rubber hose is used, and various pipe joints for connecting the pipe to another pipe are used.

As shown in FIG. 4, this type of pipe joint has a second pipe 102 having elasticity on the outer circumference of a first pipe 100 having a restricting portion 101 on the outer circumference near the pipe end to restrict movement in the axial direction.
Into the outer periphery of the second pipe 102, a connecting pipe 104 having an engaging portion 103 at one end thereof which is engaged with the restricting portion 101 and is restricted from moving in the axial direction. Of the second pipe 10
2 is fixed to the first tube 100 to connect the first tube 100 and the second tube 102.

[0004] The connecting pipe 104 is swaged in a multi-stage swaging type in which the swaging length in the axial direction is shortened to shorten a plurality of locations in the axial direction. A flat caulking type that caulks a plurality of points in a direction is known.

As a multi-stage caulking type pipe joint, as shown in FIGS. 4 and 5, a connecting pipe 104 is formed to have the same thickness from the engaging portion 103 side to the other end. In addition, as a flat crimping type pipe joint, Japanese Utility Model Laid-Open No. 64-3678.
As shown in FIG. 6 of the publication No. 7, a plurality of annular projections 106 whose inner diameter gradually increases from the protruding piece 103 side to the other end thereof are protruded from the inner surface of the connecting pipe 104. .

[0006]

However, FIG. 4 and FIG.
In the multi-stage caulking type pipe joint shown in (1), a connecting pipe 104 having the same thickness from the engaging part 103 side at one end to the other end is used. The first tube 100 is connected to the second tube 10 by caulking a plurality of locations in the same manner.
In the case where the caulking rate of each caulking portion 105 is increased to prevent the second pipe 102 from slipping out, the second pipe when hydraulic oil is supplied instantaneously is used. The caulked portion 1 of the second pipe 102
The tensile stress concentrates on the fixing part of the second pipe 102 and the second pipe 102
There is a problem that the fixed portion is cut off by caulking. In addition, when the caulking rate of each caulking 105 is reduced to prevent the second pipe 102 from being cut by the tensile stress, there is a problem that the second pipe 102 is easily pulled out by the tensile stress.

In the flattened type pipe joint shown in FIG. 6, an engagement portion 1 at one end is provided on the inner surface of the connecting pipe 104.
Since a plurality of annular projections 106 whose inner diameters gradually increase from the 03 side to the other end are protruded, the structure of the connecting pipe 104, and thus the entire structure of the pipe joint, is complicated, and there is a problem that the cost increases. Was.

The present invention has been made in view of such circumstances, and in a multi-stage caulking type pipe joint, a connecting pipe whose thickness is gradually reduced from one end to the other end is used. By making the caulking rate smaller than the caulking rate of the thick-walled side, the caulking rate of the larger pipe is prevented from coming out of the second pipe, and the caulking rate of the smaller pipe is applied to the tensile stress of the second pipe. It is an object of the present invention to configure a pipe joint capable of favorably preventing cutting by a pipe.

[0009]

A pipe joint according to the present invention comprises:
A first portion having a restricting portion on its outer periphery for restricting movement in the axial direction
A second pipe having elasticity is fitted on the outer circumference of the pipe, and a connecting pipe having an engaging portion that engages with the limiting portion at one end is fitted on the outer circumference of the second pipe. In the pipe joint in which the first pipe and the second pipe are connected by caulking a portion, the connecting pipe is gradually thinned from the engagement portion side to the other end, and the caulking rate of the caulking on the thin side is increased on the thick side. It is characterized in that it is smaller than the caulking rate of caulking.

In the present invention, the caulking rate of the thicker side of the connecting pipe, which is gradually thinner from one end to the other end, is increased to increase the fixing force of the second pipe to the first pipe. Therefore, it is possible to prevent the second pipe from falling out of the first pipe due to the behavior of the second pipe when the hydraulic oil is instantaneously supplied, and further increase the pressure contact force of the second pipe on the first pipe. 1st tube and 2nd tube
The seal between the tubes can be increased.

In addition, since the caulking rate of the caulking on the thin side of the connecting pipe is reduced to reduce the fixing force of the second pipe to the first pipe, the behavior of the second pipe when hydraulic oil is supplied instantaneously. Thus, when a tensile stress acts on the fixed portion of the second tube having the smaller swaging rate, the fixed portion of the second tube having the smaller swaging ratio can be extended. The tensile stress can be dispersed, and the cutting of the second pipe due to the tensile stress can be favorably prevented.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a front view in which a part of a pipe joint according to the present invention is sectioned, and FIG. 2 is a front view in which a part in a non-caulked state is sectioned.

The pipe joint shown in FIG. 1 has an elastic part such as a rubber hose on the outer circumference of a first metal pipe 1 having a restricting portion 11 on the outer circumference near the pipe end to limit movement in the axial direction.
The connecting pipe 3 is fitted with the pipe 2, and has an annular engaging section 31 on one end of the second pipe 2, which is engaged with the restricting section 11 at one end to restrict movement in the axial direction. The connecting pipe 3 is swaged at two places in the axial length direction by swaging means 4.
The connecting pipe 3 is plastically deformed by a and 4b, and the second pipe 2 is elastically deformed. The second pipe 2 is pressed against the outer circumference of the first pipe 1 and fixed. Tube 2 is connected.

The restriction portion 11 of the first tube 1 is, for example,
Is formed by pressing one end of the first pipe 1 in a state of being plastically deformed outwardly in a ring shape while being gripped by a chuck in the middle of the first pipe 1. The structure is not specified as long as the engaging portion 31 is engaged to restrict the movement of the connecting pipe 3 in the direction of the arrow X in FIG.

As shown in FIG. 2, the connecting pipe 3 has an inner surface fitted into the second pipe 2 having a tapered shape extending from one end of the engaging portion 31 to the other end thereof. The caulking rate of the caulked portion 4a on the thinner side is made smaller than the caulking rate of the caulked portion 4b on the thicker side.

The remaining elastic modulus of the second tube 2 is reduced by the caulking portion 4b having a higher caulking rate, so that the fixing force of the second tube 2 to the first tube 1 is increased, and the second tube 2 Of the first tube 1 is prevented.

Further, the remaining elastic modulus of the second pipe 2 is increased by the caulking portion 4a having a reduced caulking rate, so that the fixing force of the second pipe 2 to the first pipe 1 is reduced, and the second pipe 2 is fixed. When the tensile stress acts on the second pipe 2, the fixing portion of the second pipe 2 with the caulked portion 4a having a smaller caulking ratio is extended to prevent the tensile stress from being concentrated.

The first pipe 1 is a relatively short pipe such as a nipple connected to the supply / discharge port of the hydraulic actuator and a relatively long pipe connected to the supply / discharge port. And the form is not limited.

Further, as shown in FIG. 1, a plurality of projections 5 such as annular projections are formed by rolling on the outer periphery of the end of the first tube 1, specifically, at the portion where the second tube 2 is fitted. 2nd tube 2
Of the first tube 1 and the second tube 2 is improved, and the escape due to the tensile stress can be more effectively prevented.

In the pipe joint constructed as described above, the amount of elastic deformation of the second pipe 2 is increased by the caulking portion 4b having a higher caulking rate, so that the fixing force of the second pipe 2 to the first pipe 1 is increased. Also, since the caulking rate of the thicker side caulking 4b of the connecting pipe 3 gradually thinned from one end to the other end is increased, the elastic recovery by the caulking part 4b of the second pipe 2 is favorably prevented. As a result, the fixed state of the second tube 2 to the first tube 1 can be favorably maintained. Therefore, the behavior of the second pipe 2 when the hydraulic oil is supplied instantaneously makes the second pipe 2
The first pipe 1 can be prevented from falling out of the pipe 1, and the sealing force between the first pipe 1 and the second pipe 2 can be enhanced by increasing the pressure contact force of the second pipe 2 to the first pipe 1, and the hydraulic oil can be removed. Leakage can be prevented well.

Further, the amount of elastic deformation of the second tube 2 can be reduced by the caulking portion 4a having a smaller caulking rate, and the fixing force of the second tube 2 to the first tube 1 can be reduced. When a tensile stress acts on the fixed portion of the caulking portion 4a having a smaller caulking rate due to the behavior of the second pipe 2 when the caulking rate of the second pipe 2 is supplied, the caulking rate of the second pipe 2 is smaller. The fixing part by the caulking part 4a can be extended. Therefore, the tensile stress can be dispersed by this elongation, and the cutting of the second pipe 2 due to the tensile stress can be favorably prevented.

In the embodiment described above, two places in the axial direction of the connecting pipe 3 are swaged. However, three or more places may be swaged. In this case, the caulking rate of at least the caulking part on the other end side is made smaller than the caulking rates of all other caulking parts.

FIG. 3 is a sectional view showing another embodiment. In FIG. 3, a metal pipe 7 is connected to a supply / discharge port 6 of a hydraulic actuator such as a hydraulic pump, and a fitting portion 6 a is provided on the outer periphery of the supply / discharge port 6 to correspond to a hole diameter of the supply / discharge port 6. Inner diameter D1 of one end 7a of a tube 7 having a hole to be formed
And the outer diameter D2 is increased over the length necessary for fitting to the fitting portion 6a, and the sectional modulus of the one end 7a is made larger than the sectional modulus of the other portion. The inner periphery of one end of the diameter is fitted into the fitting portion 6 a of the supply / discharge port 6.

Conventionally, the supply / discharge port 107 of a hydraulic actuator such as a hydraulic pump as shown in FIG.
A fitting portion 109 having a diameter larger than the diameter of the hole is provided in the hole, and one end of a tube 108 having a hole corresponding to the hole diameter of the supply / discharge port 107 is fitted to the fitting portion 109. In this way, the diameter of the opening of the hole of the supply / discharge port 107 is increased,
Since only one end of the pipe 108 is fitted, when a large stress such as a tensile or bending stress acts on the vicinity of the connection of the pipe 108 to the supply / discharge port 107, the pipe 108 The portion near the connecting portion may be broken. However, as shown in FIG. 3, by increasing the section modulus of one end 7a of the tube 7 as compared with the section modulus of the other portions, the connection to the supply / discharge port 6 of the tube 7 can be made. Can reduce the stress such as tensile and bending stress acting on the vicinity of the connecting portion of the pipe 7, so that the pipe 7 can be easily broken by the stress without reinforcing the vicinity of the connecting portion of the pipe 7 to the supply / discharge port 6. Can be prevented.

[0025]

As described above in detail, according to the present invention, the caulking rate of the thicker side of the connecting pipe, which is gradually reduced from one end to the other end, is increased to thereby increase the first pipe of the second pipe. Since the fixing force to the second pipe is increased, the behavior of the second pipe when the hydraulic oil is instantaneously supplied can prevent the second pipe from falling out of the first pipe. Of the first tube and the second tube can be improved.

Moreover, since the caulking rate of the caulking on the thin side of the connecting pipe is reduced to reduce the fixing force of the second pipe to the first pipe, the behavior of the second pipe when hydraulic oil is supplied instantaneously. Thus, when a tensile stress acts on the fixed portion of the second tube having the smaller swaging rate, the fixed portion of the second tube having the smaller swaging ratio can be extended. The tensile stress can be dispersed, and the cutting of the second pipe due to the tensile stress can be favorably prevented.

[Brief description of the drawings]

FIG. 1 is a front view showing a cross section of a part of a pipe joint according to the present invention.

FIG. 2 is a sectional front view of a part of the pipe joint according to the present invention in a non-caulked state.

FIG. 3 is a cross-sectional view showing another embodiment.

FIG. 4 is a front view in which a part of a conventional pipe joint is sectioned.

5 is a sectional front view of a part of the conventional pipe joint shown in FIG. 4 in a non-caulked state.

FIG. 6 is a cross-sectional front view showing a part of a conventional pipe joint.

FIG. 7 is a sectional view of a conventional example corresponding to FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st pipe 11 Restriction part 2 2nd pipe 3 Connecting pipe 31 Engagement part 4a, 4b Caulking part

Claims (1)

[Claims] 1. A second pipe having elasticity is fitted on the outer circumference of a first pipe having a restriction on its outer circumference, which restricts movement in the axial direction, and the restriction is attached to one end of the outer circumference of the second pipe. In a pipe joint in which a first pipe and a second pipe are connected by fitting a connecting pipe having an engaging portion to be engaged and caulking a plurality of locations in the axial direction of the connecting pipe, the connecting pipe may A pipe joint characterized in that the caulking rate of the caulking on the thin side is made smaller than the caulking rate of the caulking on the thick side as the thickness gradually decreases from the part side to the other end.