JPH0280883A - Tube fitting - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a pipe joint made of a shape memory alloy.

[Prior art] As a pipe joint made of shape memory alloy, Japanese Patent Publication No. 544848
There is a number. This is achieved by inserting the ends of the pipes to be connected into a cylindrical joint member from both sides and heating the joint member above the transition temperature to tightly fit the joint member to the ends of the pipes to be connected. It is something that makes you

[Issue to be solved] However, the above pipe joint has the following problems.

1) Large contact (seal) pressure cannot be obtained by tightening only from the outside of the pipe. That is, if a large amount of tightening force is applied, the pipe may be deformed or, in some cases, the pipe may buckle under external pressure.

2) In addition, high joint strength against tensile loads and bending loads cannot be obtained by tightening only from the outside surface of the pipe.

3) When inserting the tube end into the joint member, it takes time and effort to align the tube end with the center of the joint member.

An object of the present invention is to provide a pipe joint that can solve the above-mentioned problems.

[Means for Solving the Problems] A pipe joint of the present invention is a pipe joint made of a shape memory alloy,
The outer cylindrical part and the inner cylindrical part, which are tightened to the outer and inner surfaces of the pipe ends of the pipes to be connected, are made into a heavy cylindrical shape by extending from the center part where the connecting pipe ends come into contact from both sides to both sides. That is.

[Function] Since the outer and inner surfaces of the pipe ends of the pipes to be connected are tightened from both sides by the outer and inner cylinder parts extending from the center of the pipe joint, sufficient tension is applied without deforming the shape of the pipes. contact(
It is possible to obtain sealing pressure, and also to obtain high joint strength against tensile loads and bending loads. Furthermore, by bringing the pipe ends of the pipes to be connected into contact with the center portion of the pipe joint, the pipe joint can be positioned at a desired position without requiring the same amount of effort.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

A pipe fitting 1 is shown in FIG. The pipe joint 1 is integrally constructed with an outer cylinder part 3 and an inner cylinder part 4 extending from a central part 2 to both sides. The extension length of the inner cylinder part 4 is shorter than the extension length of the outer cylinder part 3. Further, the tip portions 3a and 4a of the outer cylinder portion 3 and the inner tube portion 4 are gradually thinner toward the tip.

The ingredients of the shape memory alloy that is the material of this pipe joint are as follows, for example.

1) Ni-Ti system 49-51 at% Ni recovery rate 100
% (when adding 7.5% strain) 2) Cu-Zn-Al1 system
38.5-41.5wt%Zn, 6wt%A recovery rate 100% (when 4% strain is added) 3) Fe-Mn-5i system 3 Q wt%Mn, 6w
t%Si recovery rate 100% (when 4% strain is applied) 4) Fe-Cr-Ni -Mn-8i-Co system (stainless steel system) 7 to 15 wt% Cr, 3 to 10 wt% C
r-, 5-15 wt% Mn, 4-7 wt% S1.5-1
5 wt% Co, balance Fe recovery rate 100% (when 4% strain is applied) The materials of these alloys melted in an electric furnace etc. are: 1) Hot worked tjA' (hot extrusion, hot rolling, forging) etc.) 2) Cold-worked material (in rare cases, cold-open forming) 3) Obtained as a can-making (plate bending, welding) material, etc., and machined into the shape shown in Figure 1.

Then, heat treatment for shape memory is performed.

That is, a processing process is performed in which mechanical strain is applied at a temperature below the transition temperature and then strain recovery by heating at a temperature above the transition temperature is repeated. Here, the shape in its final strain recovery state is memorized in the material.

After that, the inner surface of the outer cylindrical part 3 and the outer surface of the inner cylindrical part 4 are finished by machining, taking into consideration the amount of shrinkage and tightening of the joint, the outer diameter of the pipe, the thickness of the pipe, etc., and the shape is memorized using the dimensions. be done. Then, as shown in FIG. 2, insert the joint 1 from both sides until it abuts the ends of the pipe 10 or the central part 2. To make it easier to insert the pipe end into the joint, ensure a gap of 0.5 to 1 mm between the pipe and the joint, and tighten the amount by 1 mm of the radius.
A ring with a wedge-shaped cross section is inserted between the outer cylinder part 3 and the inner cylinder part 4 to expand the diameter of the outer cylinder part and reduce the diameter of the inner cylinder part so that the diameter of the ring is approximately 4%.

Finally, the pipe fitting 1 is heated to a transition temperature of 150 to 300''C, for example in the case of the above-mentioned stainless steel, by using a flame burner, induction heating, electrical heating, resistance heating, or the like.

As a result, the outer cylindrical portion 3 recovers its shape while the inner cylindrical portion 4 recovers its diameter so that it expands.As shown in FIG. be done.

When a stainless steel material is used, it is possible to prevent corrosion of the tube end surface and the vicinity of the tube end.

Further, as shown in FIG. 4, the present invention can also be applied to a double pipe in which a cladding 11 is provided on the inner surface of the pipe.

Next, a modified example of the shape of the pipe joint 1 will be explained with reference to the drawings from FIG. 5 onwards.

In FIG. 5, the pipe joint 1 is not an integral structure, but a screw 5 is provided in the center part 2, and the outer cylindrical part 3 and the inner cylindrical part 4 are screwed together.

In FIG. 6, the contact surfaces of the outer cylindrical portion 3 and the inner cylindrical portion 4 with the tube 10 are formed into thin ring-shaped surfaces 3b and 4b, respectively. In this case, the ring-shaped surface bites into the inner and outer surfaces of the tube 10, resulting in higher joint strength.

In FIG. 7, the extension lengths of the outer cylindrical part 3 and the inner cylindrical part 4 from the central part 2 are the same. In this case, higher joint strength can be obtained due to the increased area of the clamps corresponding to the inner and outer surfaces of the tube.

FIG. 8 shows an outer cylinder part 3 and an inner cylinder part 4 having the same length and a central part 2.
It is connected by a screw 5, and the contact surfaces with the tube 0 are made into thin ring-shaped surfaces 3b and 4b.

FIG. 9 shows the ring-shaped part 3b on the inner surface of the outer cylinder part 3 and the inner cylinder part 4.
The ring-shaped portion 4b on the outer surface is provided so as to be out of phase with each other in the tube axis direction. With this shape, a particularly high withdrawal resistance is obtained.

[Effects of the Invention] The pipe joint of the present invention is of a double type, and the outer and inner surfaces of the pipe ends of the pipes to be connected are made up of an outer cylindrical part and an inner pipe extending from the center of the pipe joint. Since it is tightened from both sides depending on the part,
Sufficient contact (sealing) without deforming the tube shape
It is possible to obtain high joint strength against tensile loads and bending loads. Further, by bringing the pipe ends of the pipes to be connected into contact with the center portion of the pipe joint, the pipe joint can be positioned at a desired position without requiring the same amount of effort.

[Brief explanation of the drawing]

Figure 1 is a half-sectional view of the pipe joint, Figure 2 is an explanatory diagram of the state in which the pipe joint is set on the pipe to be connected, Figure 3 is an explanatory diagram of the connected state showing tightening, and Figure 4 is an illustration of the pipe joint set in the connecting pipe. The explanatory drawings in the case of application, FIGS. 5 to 9, are half sectional views of pipe joints having different shapes. 1... Pipe joint, 2... Center part, 3... Outer cylinder part, 4
...Inner cylinder part,]0...Manufacturer to be connected Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] A pipe joint made of a shape memory alloy, in which an outer cylindrical part and an inner cylindrical part, which are tightened to the outer and inner surfaces of the pipe ends of the pipes to be connected, extend to both sides from a central part where the connecting pipe ends abut from both sides. , a pipe joint characterized by having a double cylindrical shape.