JPH11311384A - Pipe fitting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent leakage of working all as well as falling-off of a first pipe without changing a caulking rate of a caulking cylinder and to favourably prevent cutting of the first pipe by tensile stress. SOLUTION: This pipe fitting is constituted so that height of at least one of a plural number of falling stop projections 3 provided separated from each other in the axial longitudinal direction on an outer periphery of an end part 2a of a second pipe 2 internally fitted in a first pipe 1 is lower than height of a falling stop projection 31 on the side receding from a terminal. Consequently, falling-off of the first pipe 1 is prevented by the falling stop projection 31 higher in height, a sealing property between the first pipe 1 and the second pipe 2 is improved, cutting of the first pipe 1 by tensile stress is prevented by a falling stop projection 32 low in height.

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. 5, this type of pipe joint has a plurality of annular retaining projections 102 which are spaced apart in the axial direction on the outer periphery of an end of a second pipe 101 which is fitted inside a first pipe 100 having elasticity. A plurality of caulking portions 1 are provided at a plurality of locations in the axial length direction of a metal caulking tube 103 externally fitted to the end of the first pipe 100.
The first tube 100 is elastically deformed by caulking at 04 and is fixed to the second tube 101.

[0004] The first tube 100 having elasticity has a structure in which only a rubber layer is provided, a structure in which a fiber reinforcing layer is provided in the middle and / or outer periphery of the rubber layer, a structure in which a plurality of fiber reinforcing layers are provided in the middle of the rubber layer, There are many types such as a configuration in which the fiber reinforcing layer is a spiral knit or a braided knit.

The retaining protrusion 102 is formed in a sawtooth shape with a sharpened tip, and the first tube 100 elastically deformed by the caulking portion 104 of the caulking tube 103 is cut into the retaining protrusion 102, and It is configured to prevent slipping out.

The caulking portion 10 of the caulking cylinder 103
In the first pipe 100 fixed by 4, since the tensile stress is concentrated on the biting portion to the retaining projection 102 due to the behavior when the hydraulic oil is instantaneously supplied, and the first tube 100 is easily cut from the biting portion, When the caulking diameter of the caulking cylinder 103, in other words, the caulking rate is reduced, and the amount of bite into the retaining protrusion 102 of the first pipe 100 is reduced, when a tensile stress acts on the bite portion, the bite portion is To prevent it from stretching and being cut,
Alternatively, by changing the caulking rate (caulking diameter) of the caulking tube 103 according to the above-described difference in the type of the first tube 100 and changing the position at which the retaining protrusion 102 is formed,
The amount of bite into the retaining projection 102 of the tube 100 is reduced to prevent the bite portion from being elongated and cut when a tensile stress acts on the bite portion.

[0007]

However, when the caulking rate of the caulking tube 103 is reduced to prevent the first tube 100 from being cut by the tensile stress as described above, the first tube 100 comes off due to the tensile stress. In addition, there is a problem that the sealability is deteriorated and the hydraulic oil is liable to leak.

In the case where the caulking rate (caulking diameter) of the caulking cylinder 103 is changed and the position at which the retaining projection 102 is formed is changed to prevent the first pipe 100 from being cut by the tensile stress, The caulking rate of the caulking cylinder 103 is changed according to the type difference, and
Since it is necessary to use the second pipes 101 having different formation positions of 02, the caulking rate and the second pipe 101 may be mistaken, and the management of the caulking rate and the second pipe is complicated.

The present invention has been made in view of such circumstances, and the height of at least one retaining projection for preventing the first tube from coming off is lower than the height of the retaining projection on the side away from the terminal. In this manner, without changing the caulking rate, it is possible to prevent the escape protrusion of the first pipe from leaking out and the hydraulic oil from leaking at the higher stopper projection, and to prevent the first stopper from increasing the tensile stress of the first pipe at the lower stopper projection. It is an object of the present invention to configure a pipe joint capable of favorably preventing cutting by a pipe.

[0010]

A pipe joint according to the present invention comprises:
A plurality of retaining protrusions are provided on the outer periphery of the end of the second pipe which is fitted inside the first pipe and are spaced apart from each other in the axial direction via grooves.
In a pipe joint in which the first pipe is elastically deformed by caulking of a caulking cylinder fitted to the pipe and fixed to the second pipe, at least one of the retaining protrusions of the second pipe has a height from the pipe axis. The height of the groove is lower than the height of the retaining projection on the side away from the terminal, and the depth of the groove bottom is greater than the depth of the groove bottom of the retaining projection on the side away from the terminal.

According to the present invention, the height of the plurality of retaining projections for preventing the first tube from getting into the first tube and preventing the first tube from coming out is reduced at the terminal side of the second tube and increased at the side away from the terminal. By caulking the caulking cylinder at the same caulking rate, the bite amount of the first pipe can be increased on the side of the retaining protrusion having a high height. The first tube can be prevented from falling out of the second tube due to the behavior, and the sealing force between the first tube and the second tube can be improved by increasing the pressing force of the first tube against the second tube. .
In addition, on the side of the retaining protrusion having a low height, the amount of biting of the first pipe can be sufficiently obtained at the bottom of the groove, and the pressing force against the second pipe can be reduced. When a tensile stress acts on the biting portion of the first tube due to the behavior of the first tube when the first tube moves, the biting portion can be extended, and the tensile stress is dispersed by this extension. Therefore, the cutting of the second pipe due to the tensile stress can be satisfactorily prevented, and the sealing performance between the first pipe and the second pipe can be further improved.

[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 an enlarged sectional view of a main part of a pipe joint according to the present invention, and FIG.

The pipe joint shown in FIG. 1 is a metal second fitting which is internally fitted to an end of a first pipe 1 having elasticity such as a rubber hose.
A plurality of annular retaining projections 3 are provided on the outer circumference of the end 2a of the tube 2 via a groove in the axial direction so as to be separated from each other. The caulking tube 4 made of metal is fitted inside the end of the first tube 1 and the outer periphery of the end of the first tube 1, and two portions in the axial direction of the caulking tube 4 are caulked by means of caulking. By caulking with the caulking portions 41, 41, the caulking cylinder 4 is plastically deformed and the first tube 1 is elastically deformed, and the first tube 1 is pressed against the outer periphery of the second tube 2 and fixed. The first tube 1 is connected.

The six retaining projections 3 of the second tube 2 are formed in a sawtooth shape by rolling, and the four retaining projections 31... Located on the side away from the terminal have sharpened tips. The height from the pipe shaft is increased, and the swaged portions 41,
The first tube 1 which is elastically deformed by 41 is designed to easily bite, and the two retaining protrusions 3 located on the terminal side are formed.
2, 32 are formed in a flat shape or a curved shape with a large radius of curvature without sharpening the tip, and the height from the tube axis is higher than the height of the retaining projections 31 on the side away from the terminal. The retaining projection 3 on the side that is low and the depth of the groove bottom is away from the terminal.
By making the groove deeper than the groove bottom depth of 1..., The amount of bite of the first pipe 1 can be sufficiently obtained at the groove bottom, and the pressing force against the second pipe 2 can be reduced. The four retaining projections 31 on the side away from the terminal are inclined in a saw-tooth shape in the direction away from the terminal so that the first tube 1 is more difficult to come out.

On the outer periphery of the second tube 2 near the retaining protrusion 3,
Two restricting portions 21 and 21 for restricting the movement in the axial direction are provided, and one end of the caulking cylinder 4 is engaged with the restricting portions 21 and 21 to restrict the movement in the axial direction. An annular engaging portion 42 is provided. The restriction units 21 and 21
Is a projection that is plastically deformed to the outside in an annular shape by pressing one end of the second tube 2 while holding the middle of the second tube 2 with a chuck, for example. The structure is not limited as long as the engaging portion 42 of the caulking cylinder 4 is engaged to limit the movement of the caulking cylinder 4 in the direction of the arrow X in FIG.

FIG. 3 is a perspective view showing the structure of the first tube 1. The first pipe 1 has an intermediate rubber layer 1 outside the inner rubber layer 11.
2, an outer rubber layer 13 is provided outside the intermediate rubber layer 12, and a first fiber reinforcing layer 14 is formed by spirally winding a reinforcing thread between the inner rubber layer 11 and the intermediate rubber layer 12. The second fiber reinforcement layer 15 is formed by braiding a reinforcing thread between the intermediate rubber layer 12 and the outer rubber layer 13 to provide a total of five layers. A single wire is used as the reinforcing yarn of the first fiber reinforcing layer 14. After the single wire is spirally wound in one direction to form a lower knitting layer, the single wire is spirally wound in the other direction to form an upper knitting. A layer is formed to enhance the expandability, and the second fiber reinforcing layer 15 enhances the burst pressure resistance and the tensile resistance.

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.

In the pipe joint constructed as described above, the caulking portion 41,
41 to deform the first tube 1 elastically.
The tube 1 is bitten into the retaining projection 3 and fixed. In this case, the retaining projection 31 on the side of the second tube 2 that is away from the terminal.
Since the tip is sharp and its height from the tube axis is high, the amount of biting into the retaining projection 31 of the first tube 1 can be increased. Therefore, it is possible to prevent the first pipe 1 from falling out of the second pipe 2 due to the behavior of the first pipe 1 when the hydraulic oil is supplied instantaneously, and further, to prevent the first pipe 1 of the second pipe 2 from coming off.
The sealing performance between the first tube 1 and the second tube 2 can be increased by increasing the pressure contact force on the first tube 1 and the second tube 2.

Further, the retaining protrusion 32 on the terminal side of the second pipe 2,
The first tube 32 has a flat shape at its distal end, its height from the tube axis is low, and its groove bottom depth is deeper than the groove bottom depth of the retaining projections 31 on the side away from the terminal. The amount of biting into the first retaining projection 32 can be sufficiently obtained at the bottom of the groove, and the pressing force against the second pipe 2 can be reduced. Accordingly, when a tensile stress acts on a portion of the first tube 1 that bites into the retaining projection 3 due to the behavior of the first tube 1 when the hydraulic oil is instantaneously supplied, it is possible to extend the biting portion. This elongation makes it possible to disperse the tensile stress, to prevent the first pipe 1 from being cut by the tensile stress, and to further improve the sealing performance between the first pipe 1 and the second pipe 2. Can be further increased.

By making the height of the retaining projections 3 different in this way, the caulking rate at the position separated in the axial direction of the caulking cylinder 4 is the same, but the influence of the type of the first tube 1 is affected. The pressing force of the first tube 1 against the second tube 2 can be increased / decreased without the need for changing the swaging rate and the position of the retaining projection 3 according to the type of the first tube 1. In addition, the workability can be improved, and the cost can be reduced.

The first pipe 1 having five layers is provided with a first fiber reinforcing layer 14 between the inner rubber layer 11 and the intermediate rubber layer 12.
However, since the single wire is composed of the lower knitting layer wound in one direction and the upper knitting layer wound in the other direction, the expandability and the extensibility can be enhanced. Therefore, the pulsation of the hydraulic oil flowing in the first pipe 1 can be favorably absorbed. Further, the second fiber reinforcing layer 15 between the intermediate rubber layer 12 and the outer rubber layer 13
Is braided, so that the burst pressure resistance and the tensile resistance can be improved.

FIG. 4 is a perspective view showing another structure of the first tube 1. The first tube 1 in FIG. 4 is provided with an intermediate rubber layer 12 outside the inner rubber layer 11 as in FIG.
2, an outer rubber layer 13 is provided outside the inner rubber layer 1.
A first fiber reinforcing layer 14 formed by spirally winding a reinforcing yarn in one direction between the first rubber layer 1 and the intermediate rubber layer 12 is provided.
A second fiber reinforcing layer 15 formed by spirally winding a reinforcing yarn in one direction between the second rubber layer 13 and the outer rubber layer 13 is provided, and the entire structure is composed of five layers.

In the configuration of FIG. 4, the first and second
Since the fiber reinforcing layers 14 and 15 have a structure in which the reinforcing yarn is spirally wound in one direction, the expandability of the first tube 1 can be made higher than that of FIG. Of the end 2a can be reduced. Therefore, the first pipe 1 can be inserted into the outer circumference of the end 2a of the second pipe 2 with a small insertion force, and workability can be improved.

In the embodiment described above, six retaining projections 3 are provided, and two retaining projections 3 located on the terminal side are provided.
Although the height of 2 is made lower than the height of the four retaining projections 31 on the side away from the terminal, the total number of retaining projections 3 and the number of retaining projections 32 whose height is low are not particularly limited. The retaining projection 32 may be provided continuously with the groove of the retaining projection 31 as shown in FIG. 1 or may be provided separately from the groove. The caulking cylinder 4 may be caulked at two places in the axial direction, or may be caulked at three or more places.

[0025]

As described in detail above, according to the present invention, the first
The height of the plurality of retaining projections to prevent the tube from slipping into the tube is reduced on the terminal side of the second tube and increased on the side away from the terminal, so by caulking the caulking cylinder at the same caulking rate On the side of the retaining protrusion having a high height, the amount of biting of the first pipe can be increased, and therefore, the first pipe comes out of the second pipe due to the behavior of the first pipe when hydraulic oil is supplied instantaneously. Can be prevented, and the sealing force between the first tube and the second tube can be enhanced by increasing the pressure contact force of the first tube on the second tube. Also, on the side of the retaining projection having a low height, the first
The amount of bite in the pipe can be obtained at the bottom of the groove,
In addition, since the pressure contact force on the second pipe can be weakened, when the hydraulic oil is instantaneously supplied, the behavior of the first pipe causes a tensile stress to act on the biting portion of the first pipe into the retaining projection. The bite portion can be elongated, and thus, the tensile stress can be dispersed by the extension, and the cutting of the second tube due to the tensile stress can be favorably prevented.
The sealing between the first tube and the second tube can be further enhanced.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of a pipe joint according to the present invention.

FIG. 2 is an overall front view in which a part of the pipe joint according to the present invention is sectioned.

FIG. 3 is a perspective view showing a configuration of a first pipe of the pipe joint according to the present invention.

FIG. 4 is a perspective view showing another configuration of the first pipe of the pipe joint according to the present invention.

FIG. 5 is a front view showing a cross section of a part of a conventional pipe joint.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st pipe 2 2nd pipe 3,31,32 Prevention protrusion 4 Caulking cylinder 41,41 Caulking part

Claims (1)

[Claims] 1. A plurality of retaining projections are provided on an outer periphery of an end portion of a second pipe which is internally fitted in the first pipe and are spaced apart in a longitudinal direction through a groove, and are externally fitted to the first pipe. In a pipe joint in which the first pipe is elastically deformed by caulking of a caulking cylinder and fixed to the second pipe, at least one of the retaining projections of the second pipe has a height from the pipe axis that is away from the terminal. A pipe joint characterized in that the height of the groove bottom is lower than the height of the retaining projection, and the depth of the groove bottom is greater than the depth of the groove bottom of the retaining projection on the side away from the terminal.