JPS6254565B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a shrink ring whose inner peripheral surface has a frustoconical shape, which is attached to the outer periphery of the plug-in pipe joint body from the end side after a thin-walled metal pipe is inserted into the plug-in pipe joint body. A plug-in joint for thin-walled metal pipes in which the diameter of the plug-in pipe fitting body is reduced by fitting, and the plug-in type pipe fitting body and the thin-walled metal pipe are brought into close contact and joined at the reduced diameter part. It is about legal improvements.

Traditionally, thick-walled pipes such as lead pipes and vinyl pipes have been used for liquid transfer pipes such as water pipes.
Each of them has drawbacks in terms of strength and temperature adaptability, so in recent years, thin-walled metal pipes, typified by stainless steel pipes, have been increasingly used in place of these pipes. Taking stainless steel pipes, which are the most commonly used thin-walled metal pipes, as an example, thin-walled stainless steel pipes have excellent strength and are resistant to temperature changes, but they are harder and more durable than other materials. Moreover, since it is impossible to perform processing such as thread cutting because of the thin wall, the following method of joining using pipe joints has been adopted.

That is, as shown in FIG. 1, a cap nut-shaped tightening member A having a female thread on the inner surface is screwed onto a joint body having a male thread on the outer surface of the end, and one end of the sleeve C is pressed. A method has been adopted in which the sleeve C is crimped onto the outer peripheral surface of the thin-walled metal tube D and the end of the joint body B to form a liquid seal. B is harder, and tightening member A is used to increase the pressure resistance of the joint in the axial direction and to ensure a more secure seal.
The end of the sleeve C on the side of the tightening member A was bitten into the outer circumferential surface of the thin metal tube D as shown in FIG.

However, when attempting to join thin-walled metal pipes using such a pipe fitting, the tightening member A must have a female thread on the inner surface, and the fitting body B must have a male thread on the outer surface of the end. As a result, thick-walled castings are used, which increases the size and weight of the necessary components, resulting in an increase in cost and poor economic efficiency.

As a method for joining thin-walled metal pipes that prevents such defects, a method using a plug-in pipe joint disclosed in Japanese Patent Publication No. 55-46553 ``Coupling for joining cylindrical members'' has been implemented. I'm getting old.

In this method, the plug-in joint body is made of a relatively thin metal material, and a contraction ring with a truncated conical inner surface is fitted onto the outer periphery of the joint body from the end side of the joint body. This is a method of joining a joint body and a thin-walled metal tube by reducing the diameter of the end of the joint body and bringing the thin-walled metal tube and the joint body into close contact at the reduced-diameter portion.

This method is extremely economical, but if you try to implement this method, you will need to loosely fit a shrink ring around the outer circumference of the thin metal tube to be inserted into the plug-in type pipe fitting body. Insert each thin-walled metal pipe into the plug-in type pipe fitting body from both sides, and then press and move the contraction rings on both sides toward the joint body using a pressing tool to reduce the diameter of both ends of the joint body. However, this method is only possible when the joint body is in the shape of a straight tube and the force used on each contraction ring is the same and opposite force, and the plug-in type It is impossible to implement this method when the pipe joint body is curved like an elbow or when there is no insertion part for a thin metal pipe on the other side like a branch pipe of Qi.
In order to prevent such drawbacks, a plug-in pipe joint body as shown in Fig. 2 has been proposed in recent years, in which a projection part is provided on the outer periphery of the plug-in pipe joint body to engage with a fixing claw of a pressing tool. . However, providing a protrusion on the outer periphery of the plug-in type pipe fitting body is expensive because the plug-in type pipe fitting body must be manufactured by means such as casting, and the thin-walled metal pipe to be joined and the fitting body are expensive. This had the disadvantage that the metal parts were made of different materials, resulting in defects such as potential corrosion.

The inventors of the present invention have conducted intensive research to eliminate the drawbacks of the conventional method of joining thin-walled metal pipes using plug-in pipe joints, and have found that the main body of the plug-in pipe joint is made of the same material as the thin-walled metal pipes to be joined. In addition, the tube end of a thin-walled metal material with approximately the same inner diameter is expanded by a predetermined length so that the inner diameter is slightly larger than the outer diameter of the thin-walled metal tube to be joined, and the end of the tube expansion is used. If the entire circumference of the flare part is held by a split-shaped grip ring whose inner shape almost matches the outer shape of the flare part, and a shrink ring is fitted to the outer circumference of the pipe joint body from the end side, It is economically inexpensive, works well regardless of the condition of the opposite side of the plug-in fitting body to which the thin-walled metal pipes are joined, and is a good joining method that does not cause potential corrosion. They investigated this and completed the present invention.

That is, in the present invention, thin-walled metal tubes made of the same material and having almost the same inner diameter as the thin-walled metal tubes to be joined are lengthened by a predetermined length so that the inner diameter of the end of the thin-walled metal tubes is slightly larger than the outer diameter of the thin-walled metal tubes to be joined. A thin metal pipe to be joined, which has a contraction ring having a truncated conical portion on its inner circumferential surface loosely fitted around its outer periphery, is inserted into the expanded section of the plug-in type pipe fitting main body, and then the plug-in type pipe fitting is connected. The entire circumference of the tube expansion end portion of the main body is held by a two-split grip ring having an inner shape that almost matches the outer shape of the main body, and the grip ring is held by a U-shaped fixing claw of a pressing tool, and the contraction ring is removed. Press it against the plug-in pipe fitting body side with the U-shaped movable claw of the pressing tool to reduce the diameter of the end of the plug-in pipe fitting body, and the reduced diameter part connects the plug-in pipe fitting body with the thin-walled metal. The present invention provides a plug-in joining method for thin-walled metal pipes, which is characterized by bringing the pipes into close contact with the pipes.

EMBODIMENT OF THE INVENTION Hereinafter, the plug-in joining method of thin-walled metal tubes according to the present invention will be explained in detail with reference to the drawings.

FIG. 3 is an explanatory diagram showing a cross section of the upper half of an embodiment in a state in which the method of the present invention is being carried out, and FIG. 4 is a cross-sectional view taken along the line X--X in FIG.

In the drawings, 1 is a thin-walled metal pipe such as a thin-walled stainless steel pipe to be joined, and 2 is a plug-in type pipe joint body into which the thin-walled metal pipe 1 is inserted and joined. This plug-in type pipe joint body 2 is made of the same material as the thin-walled metal tube 1 and has an inner diameter that is almost the same as the inner diameter of the thin-walled metal tube 1.The inner diameter of the tube end of the thin-walled metal tube is slightly larger than the outer diameter of the thin-walled metal tube 1. The inner surface of the tube expansion end portion 2a (hereinafter referred to as flare portion) of the plug-in type pipe joint body 2 manufactured in this way is the thin-walled metal tube 1 to be inserted. It serves as a stopper against which the end of the tube comes into contact. Reference numeral 3 denotes a shrink ring that is fitted onto the outer periphery of the end of the plug-in pipe joint main body 2 to reduce the diameter of the end of the plug-in pipe joint main body 2;
is made of a harder material than the plug-in type pipe fitting main body 2, and has a truncated conical part on its inner peripheral surface.
is contracted. Reference numeral 4 denotes a split grip ring, whose inner surface 4a has an inner shape that almost matches the outer shape of the flared portion 2a of the plug-in pipe joint body 2, and its outer surface 4b has a shape that matches the outer shape of the flared portion 2a of the plug-in pipe joint body 2. Various shapes such as a tapered shape, an arcuate shape, and a combination thereof can be adopted so that it can be held securely by the fixed claw and force can be easily applied in the direction of the flare portion 2a. Further, it is preferable that the grip ring 4 is connected by a hinge portion 4c so that it is easy to handle and difficult to lose. Reference numeral 5 denotes a pressing tool that applies a force to reduce the diameter of the end of the plug-in pipe joint body 2, and this pressing tool 5
a main body 5a to which a U-shaped fixing claw 5b is fixed, which holds a grip ring 4 attached to the outer periphery of the flare portion 2a of the plug-in pipe joint main body 2 on its inner peripheral surface;
Hydraulic cylinder 5 attached to the main body 5a
It consists of a U-shaped movable claw 5d that is moved by C to press the contraction ring 3 against the outer periphery of the end of the plug-in pipe joint body 2. This pressing tool 5
The reason why both the fixed claw 5b and the moving claw 5d are U-shaped is that when the thin-walled metal pipe 1 is inserted into the plug-in type pipe fitting main body 2, the fixed claw 5b is inserted into the plug-in type pipe fitting body 2. The thin-walled metal tubes are attached to the outer periphery of the grip ring 4 attached to the outer periphery of the joint body 2, and the movable claw 5d is attached to the outer periphery of the thin-walled metal tube 1 and to the back surface of the contraction ring 3, and are joined after the welding operation is completed. 1 and the plug-in type pipe fitting main body 2. In order to satisfy these requirements, the U-shaped inner diameter of the fixed claw 5b must be removed from the plug-in type pipe fitting main body 2 at the smallest part. The inner diameter of the U-shape of the movable claw 5d must be larger than the outer diameter of the thin metal tube 1.

To implement the method of the present invention with such a configuration,
First, the contraction ring 3 is loosely fitted around the outer periphery of the thin-walled metal tube 1 with its frusto-conical large diameter portion facing the tube end, and then the thin-walled metal tube 1 is fitted so that the tube end touches the inner surface of the flared portion 2a. Insert into the plug-in type pipe fitting main body 2 until they touch. Next, the flare part 2a of the plug-in pipe joint body 2
Attach the split-shaped grip ring 4 to the outer periphery, and then press the pressing tool 5 so that the fixed claw 5b holds the grip ring 4, and the movable claw 5d is attached to the opposite side of the shrink ring 3 from the plug-in pipe joint body 2. The main body 5a of the pressing tool 5 is installed so as to be located on the surface side.
When the moving claw 5d is moved toward the fixed claw 5b by supplying hydraulic pressure to the hydraulic cylinder 5c attached to the hydraulic cylinder 5c, the moving claw 5d fits the contraction ring 3 onto the outer periphery of the end of the plug-in pipe joint body 2. Since the fitted part of the plug-in pipe joint main body 2 is contracted,
The inner surface of the plug-in pipe joint body 2 and the outer surface of the thin-walled metal tube 1 come into close contact with each other at the contracted portion, and a sealing surface and a desired joint strength can be obtained at the same time. When the connection between the thin-walled metal pipe 1 and the plug-in pipe joint body 2 is completed in this way, the hydraulic pressure supplied to the hydraulic cylinder 5c of the pressing tool 5 is released, and the movable claw 5
After retracting d, the pressing tool 5 is removed, and then the grip ring 4 is split into two and removed from the flare portion 2a of the plug-in pipe joint body 2.

The plug-in joining method for thin-walled metal pipes according to the present invention as detailed above does not require the use of the conventional plug-in joint main body made of a cast product with a protrusion on the outer periphery. This plug-in type pipe fitting body can be manufactured inexpensively and easily by simply expanding the pipe end of almost the same thin-walled metal material to a predetermined length, and there is no need to worry about potential corrosion. Unlike conventional plug-in fittings, there is no protrusion on the outer periphery that securely engages the fixing claw of the pressing tool. This can be solved by using the outer periphery of the flared part, which has a small change in diameter, so it is impossible to reliably join thin-walled metal pipes by holding only half the periphery, like the fixed claw of a pressing tool. This is an epoch-making method that solves this problem by using a two-split grip ring, which makes it possible to join thin-walled metal pipes inexpensively, easily, and reliably. This method has the advantage that it can be used in a variety of situations, since as long as only the joint is in the shape of a straight tube, the other end can be in any condition, and its industrial value is extremely large. There is.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a cross-section of the upper half of a conventional pipe joint for thin-walled metal pipes in use, and Fig. 2 is an explanatory diagram showing a cross-section of the upper half of the main body of a conventional plug-in pipe joint for thin-walled metal pipes. Fig. 3 is an explanatory diagram showing a cross section of the upper half of one embodiment in a state in which the method of the present invention is being carried out;
The figure is a sectional view taken along the line X--X in FIG. 3. 1... Thin-walled metal pipe, 2... Plug-in pipe fitting body,
2a...Flare portion, 3...Contraction ring, 4...Grip ring, 4a...Inner surface, 4b...Outer surface, 4
c...Hinge part, 5...Press tool, 5a...Main body, 5b...Fixed claw, 5c...Hydraulic cylinder, 5
d...Moving claw.

Claims (1)

[Scope of Claims] 1. A thin-walled metal material made of the same material and having almost the same inner diameter as the thin-walled metal tubes to be joined. A thin-walled metal pipe to be joined, which has a contraction ring having a truncated conical portion on its inner peripheral surface loosely fitted around its outer periphery, is inserted into the expanded part of the plug-in type pipe joint body that has been expanded to a certain extent, and then the plug-in type pipe fitting body is expanded. The entire periphery of the end of pipe expansion of the pipe joint body is held by a two-split grip ring having an inner shape that almost matches the outer shape of the pipe joint body, and the grip ring is held by a U-shaped fixing claw of a pressing tool. Press the shrink ring against the plug-in pipe fitting body side with the U-shaped movable claw of the pressing tool to reduce the diameter of the end of the plug-in pipe fitting body, and use the reduced diameter part to connect the plug-in pipe fitting body. A plug-in joining method for thin-walled metal tubes, which is characterized by closely contacting thin-walled metal tubes. 2. The plug-in method for joining thin-walled metal tubes according to claim 1, which uses a grip ring connected to a split grip ring at a hinge portion.