JPH08210575A - Pipe joint - Google Patents

Abstract

PURPOSE: To provide a pipe joint inexpensively, which is capable of a connective state so well as allowing the vibration and expansion of a pipeline by dispensing with any boring work from a pipe end part for restricting the fitting length of an insert pipe on the inside of a metallic conduit subject to connection, and making improvements in a reduction in workhours and a yield rate of each product. CONSTITUTION: A connecting cylinder 3 is attached to the outside of a metallic conduit subject to connection in making it engage with a circumferential groove 11 formed on a peripheral surface of this conduit. An insert pipe 2 is fitted in an inner part of each pipe end of two metallic conduits 1 and 1, and further an elastic pipe 4 is inserted into an annular clearance between the metallic 1 and the connecting cylinder 3, performing its slip stopping and clamping, and the metallic conduit 1 and the elastic pipe 4 are connected together after allowing the expansion and flection of this elastic pipe 4 within the elastic range. In addition, a caulking projection 13 is formed into such a mode as being projected inside by way of caulking a peripheral wall of the metallic conduit 1 for forming the circumferential groove 11, and thereby fitting length of the insert pipe 2 into the metallic conduit 1 is restricted by what a tip of this insert pipe 2 comes into contact with the caulking projection 13.

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 metal pipes for supplying and discharging pressure oil in various hydraulic circuits.

[0002]

2. Description of the Related Art In various hydraulic drive devices widely used in many industrial fields in order to perform a predetermined work by the operation of a hydraulic actuator, in order to supply and discharge the hydraulic oil to and from the hydraulic actuator. Requires a long length of hydraulic pipe, and in this hydraulic pipe, metal pipes are often used to cope with high pressure of hydraulic oil. And various pipe joints for connecting the metal pipe and other components at the end of the pipe.

In this type of pipe joint, in addition to the original function of connecting the pipes, various additional functions are required depending on the purpose of use. For example, a hydraulic pipe for a hydraulic drive device such as a power steering device (power steering device) for assisting the steering vibrates according to the vibration of the vehicle body while traveling, and the ambient temperature changes. Therefore, the pipe joint used for this hydraulic pipe is required to maintain the connected state while allowing the vibration and the expansion and contraction. Conventionally, a pipe joint as shown in FIG. 4 has been used. Has been.

Reference numeral 1 in the figure denotes a metal tube to be connected.
An expanded diameter portion 10 is provided on the inside of the metal pipe 1 over a predetermined length from the pipe end portion, an insertion pipe 2 is fitted in the expanded diameter portion 10, and an outside pipe end of the metal pipe 1 is provided. A connecting cylinder 3 having a larger diameter than this is attached near the portion. The connecting cylinder 3 is provided with a fixing flange 30 protruding inward at an opening edge on one side, and the connecting cylinder 3 is attached to the metal pipe 1 such that the inner circumference of the fixing flange 30 is the outer circumference of the metal pipe 1. , And by engaging the peripheral groove 11 formed over the entire circumference by caulking the peripheral wall in this state, the opening edge on the other side is coaxial with the tube end edge of the metal tube 1 as shown in the drawing. The movement in the axial direction is restricted at the position aligned with.

Thus, an annular gap is formed inside the connecting cylinder 3 fixed in this way, between the outer peripheral surface of the metal tube 1 and the opening on the tube end side. The elastic tube 4 made of an elastic material such as rubber is inserted into the gap and is fixed so as not to come off. The retaining lock is performed by, for example, caulking inward at one or a plurality of locations (two locations in the figure) in the middle of the connecting tube 3 and inclining the elastic tube 4 by the caulking portions 3a and 3a. It is realized by grasping from the outside.

The other end of the elastic tube 4 as described above is appropriately connected to another metal tube (not shown) or another component member, whereby the metal tube 1 is connected to the elastic tube 4 via the connecting tube 3.
It will be connected with. In this connected state, the metal tube 1 is allowed to be displaced in the axial direction according to the expansion and contraction of the elastic tube 4, and is also allowed to be displaced in a plane orthogonal to the axis according to the bending of the elastic tube 4, It is possible to maintain a good connection state while absorbing the vibration and expansion and contraction of the hydraulic pipe that occur as described above.

As shown in the figure, the inner pipe 2 is a spiral pipe formed by spirally winding a narrow metal plate, and is constructed so as to absorb the pulsation of the working oil flowing inside. Further, the elastic tube 4 is pressed against the outer peripheral surface of the metal tube 1 by the caulking portions 3a, 3a of the connecting tube 3, and also functions as a sealing means for preventing pressure oil from leaking from the inside of the metal tube 1. I am doing it.

[0008]

In the conventional pipe joint having the above-described structure, since the insertion pipe 2 is fitted inside the metal pipe 1, the pipe end extends over a predetermined length range. The enlarged diameter portion 10 is formed. The expanded diameter portion 10 is necessary for limiting the fitting length of the insertion tube 2 and for limiting the axial movement of the insertion tube 2 with respect to the metal tube 1 to prevent the insertion tube 2 from coming off. As shown in the drawing, the insertion tube 2 is constrained so that the tube end is abutted against the step portion on the inner back side of the expanded diameter portion 10.

The expanded diameter portion 10 is formed by boring from the end of the pipe, and is a metal pipe 1 used for hydraulic piping.
Is generally a small-diameter thin-walled tube, so
However, there is a problem in that it takes a lot of time and labor to form the above-mentioned products, and that the rate of occurrence of processing defects is high, resulting in deterioration of product yield.

The present invention has been made in view of the above circumstances, and the extension length of the insertion pipe inside the metal pipe to be connected and the axial movement after the insertion are expanded from the pipe end portion. Limit without forming the diameter part,
An object of the present invention is to provide a pipe joint that can reduce the number of processing steps and improve the product yield.

[0011]

The pipe joint according to the present invention comprises:
An insertion tube is fitted to the inside of the metal tube over a predetermined length from the tube end, and is axially constrained by engagement with a peripheral groove formed by caulking the peripheral wall on the outside near the tube end of the metal tube. Then, a cylindrical connecting tube is attached, and the elastic tube is inserted from the tube end side into the annular gap between the inner circumference of the connecting tube and the outer circumference of the metal tube, and fixed by retaining. In a pipe joint for connecting an elastic pipe and the metal pipe, the edge of the insertion pipe is formed at a position corresponding to a circumferential groove for engagement of the connecting cylinder so as to project inward of the metal pipe. It is characterized in that it is provided with a caulking projection for limiting the fitting length of the insertion tube by abutting against the.

[0012]

According to the present invention, when the peripheral groove for engaging the connecting cylinder to the outside of the metal pipe is formed by caulking the peripheral wall, it projects to the inside of the metal pipe at a position corresponding to the peripheral groove. Utilizing the fact that the caulking projections are formed, the edge of the insertion tube fitted inside the metal tube is brought into contact with the caulking projections to limit the fitting length, and the movement of the insertion tube after fitting is limited.

[0013]

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 vertical cross-sectional view showing a connection state by a pipe joint according to the present invention with a part thereof broken, and FIG. 2 is an enlarged cross-sectional view of a main part thereof.

In the figure, reference numerals 1 and 1 denote metal pipes to be connected. These metal pipes are connected to each other by elastic pipes 4 which are inserted into the respective outsides and fixed to the respective connecting pipes 3 and 3 so as not to come off. . Further, an inner insertion tube 2 is fitted to the inside of one of the metal tubes 1 shown as a cross section for a predetermined length from the tube end portion.

The connecting cylinder 3 is provided with a fixing flange 31 projecting inward at an opening edge on one side of a cylinder having a diameter larger than that of the metal tube 1, and an inner peripheral edge of the fixing flange 31 of the metal tube 1. By fitting to the outside, by engaging the peripheral groove 11 formed over the entire circumference by caulking the peripheral wall in this state,
As shown in the drawing, the movement in the axial direction is restricted at the position where the opening edge on the other side is coaxially aligned with the tube end edge of the metal tube 1, and the tube end side is held between the outer peripheral surface of the metal tube 1 and It is attached with an opening and an annular gap.

The peripheral groove 11 is fitted with a fixing flange 31 at a predetermined position of the metal tube 1, and the deformation of the peripheral wall to the outside is restricted except for a predetermined width range on both sides of the fitting portion. As shown in the drawing, the unconstrained portions remaining on both sides of the fixed flange 31 are formed outside by a procedure of applying a pressing force in the axial direction to the pipe end portion of the metal pipe 1 in this state. At this time, the fixed flange 31 is held between the raised portions 12, 12 on both sides, and the engagement with the circumferential groove 11 is achieved at the same time.

FIG. 3 is an explanatory diagram of a method of forming the circumferential groove 11. The deformation of the metal pipe 1 on the pipe end side is caused by the cylindrical outer punch 5 inserted in the annular gap between the metal pipe 1 and the connecting pipe 3.
Further, the deformation on the opposite side is restrained on both sides of the fixed flange 31 except for a predetermined width by the chuck 6 that holds the entire circumference of the metal tube 1.

In this state, the inner punch 7 is advanced along the inner circumference of the outer punch 5 and abutted against the pipe end portion of the metal pipe 1 as shown in the figure, and then the outer punch 5 together with the inner punch 7 is outlined in the figure. The pressure is applied to the pipe end by advancing in the direction indicated by the symbol. As a result, the peripheral wall between the tip of the outer punch 5 and the holding portion by the chuck 6 and the fixed flange 31 rises outward, respectively, and as shown in FIG. 2, the raising portion 1 that holds both sides of the fixing flange 31.
2, 12 are formed, and the circumferential groove 11 is formed between them.

In the process of forming the circumferential groove 11 performed as described above, with the protrusion of the raised portions 12, 12 on the outer peripheral side of the metal tube 1, the space between them, that is, the portion corresponding to the circumferential groove 11, is reversed. Will be projected inward, and the inner peripheral surface of the metal tube 1
As shown in FIG. 2, at the position where the peripheral groove 11 is formed on the outer peripheral surface,
A caulking protrusion 13 is formed so as to protrude inward over the entire circumference.

In the pipe joint according to the present invention, the insertion pipe 2 is directly fitted to the inner periphery of the metal pipe 1 on the pipe end side, and the caulking protrusion 13 protruding on the inner surface of the metal pipe 1 has a tip edge. The fitting length is restricted by abutting. In the process of forming the peripheral groove 11 described above, since the outer punch 5 restrains the deformation from the outside on the tube end side of the protruding portion of the caulking projection 13, there is almost no deformation on the inner circumference side. The fitting is done without any trouble.

The elastic tube 4 is made of an elastic material such as rubber, and is connected to the outer circumferences of the metal tubes 1 and 1 and the connecting cylinders 3 and 3 respectively.
Both ends are respectively inserted into an annular gap formed between the inner circumference of the connecting cylinder 3 and the inner circumference of the inner circumference of the The caulking portions 3a, 3a formed by caulking inwardly are gripped from the outside and fixed to prevent coming off.

As a result, the metal tubes 1 and 1 are connected to both ends of the elastic tube 4 through the connecting tube 3, and both metal tubes 1 and 1 are axially moved within the range of expansion and contraction of the elastic tube 4. Can be relatively moved, and can be flexibly deformed in a plane orthogonal to the axis within the elastic range of the elastic tube 4, increasing the degree of freedom in arranging both metal tubes 1, 1. It is possible to maintain good connection with the elastic tube 4 while absorbing vibration and expansion and contraction due to the action of external force.

Further, since the insertion tube 2 is restricted in its movement by bringing one end edge into contact with the caulking projection 13 on the inner surface of the metal tube 1 as described above, its position in the axial direction is accompanied by the vibration and expansion and contraction. The initial fitting position can be reliably maintained without changing. Similar to the conventional insertion tube shown in FIG. 4, the illustrated insertion tube 2 is a spiral tube in which a narrow metal plate is spirally wound, and is configured to absorb the pulsation of hydraulic oil flowing inside. A retaining ring 20 having an appropriate width and having an annular shape is externally fitted to the other end of the insertion tube 2 configured as a spiral tube to prevent fraying from the same side.

As described above, the caulking projection 13 for positioning the inner insertion tube 2 is formed so as to project to the inner surface side due to the formation of the circumferential groove 11 on the outer side of the metal tube 1, but as shown in FIG. In order to obtain a protrusion amount that can surely come into contact with the end edge of the insertion tube 2, the thickness of the inner peripheral edge of the fixed flange 31 provided around the connecting tube 3 is made smaller than that of the conventional one, and the inner peripheral edge is reduced. It is effective to reduce the width of the circumferential groove 11 formed so as to sandwich the groove. As is clear from the comparison between FIG. 2 and FIG. 4, the fixing flange 31 in the pipe joint according to the present invention is thinner than the fixing flange 30 in the conventional pipe joint. This is a caulking protrusion having a large protrusion amount inside the metal tube 1.
To get 13.

Further, the elastic tube 4 is strongly pressed against the outer peripheral surface of the metal tube 1 when the peripheral edge of the connecting tube 3 is fixed by caulking to prevent the pressure oil from leaking from the inside of the metal tube 1. It also functions as a sealing means, and these configurations are the same as the conventional ones.

In the above description, an example of use in a hydraulic drive device for a vehicle such as a power steering device has been described, but the pipe joint according to the present invention is attached to a hydraulic drive device other than that for an automobile. It can be used to connect metal pipes for supplying / discharging pressure oil in hydraulic pipes, and can also be used for connecting metal pipes in pipes for supplying / discharging various fluids, and similar effects cannot be obtained. Needless to say.

[0027]

As described above in detail, in the present invention, the elastic tube is fixed so as to prevent the metal tube having the tube end fitted with the insertion tube from coming off from the connecting tube engaged with the outside of the metal tube. In the configuration of connecting with, the fitting length of the insertion tube,
Since the outer peripheral wall is swaged to form a circumferential groove for engagement of the connecting cylinder, it is limited by abutting against a caulking protrusion projecting to a corresponding position on the inner surface side of the metal pipe. No need for boring from the pipe end, which was previously done, can reduce the number of processing steps and improve the product yield, and the pipe joint that maintains the good connection state while allowing the vibration and expansion and contraction of the pipe is inexpensive. The present invention has excellent effects such as that

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a connection state of a pipe joint according to the present invention with a part thereof broken away.

FIG. 2 is an enlarged sectional view of a main part of a pipe joint according to the present invention.

FIG. 3 is an explanatory diagram of a method of forming a circumferential groove.

FIG. 4 is an enlarged sectional view of a main part of a conventional pipe joint.

[Explanation of symbols]

 1 Metal tube 2 Insertion tube 3 Connection tube 4 Elastic tube 11 Circumferential groove 12 Raised part 13 Caulking protrusion 31 Fixed flange

Claims (1)

[Claims] 1. An insertion tube is fitted inside a metal tube over a predetermined length from the tube end, and is engaged with a peripheral groove formed by caulking a peripheral wall on the outside of the metal tube near the tube end. A cylindrical connecting tube is attached while being restrained in the axial direction by means of an elastic tube inserted from the tube end side into the annular gap between the inner circumference of the connecting tube and the outer circumference of the metal tube to secure it in place. By doing so, in the pipe joint for connecting the elastic pipe and the metal pipe, the pipe is formed at a position corresponding to the circumferential groove for engagement of the connecting cylinder so as to project inside the metal pipe, A pipe joint comprising a caulking protrusion that limits a fitting length of the insertion tube by contact with an edge of the insertion tube.