JPS5868487A - Production of multilayered pipe utilizing shape storage effect - Google Patents

Abstract

PURPOSE:To obtain a multilayered pipe of 2-3 layers having good adhesive strength by superposing a shape storage alloy on the inside or outside side surface of an inexpensive base material pipe. CONSTITUTION:In the production of a multilayered pipe wherein a pipe having corrosion resistance on at least one side surface of either of the inside and outside side surfaces of a base material pipe 2, an alloy pipe having a shape storage effect is used as a pipe having corrosion resistance. After the alloy pipes 1, 1 are worked and deformed at a temp. lower than the Ms point, the pipes 1, 1 are fitted onto the pipe 2. The pipes 1, 1 are heated with a burner 3 at a temp. higher than the As point to reset the pipes 1, 1 to the shape before the working and deformation, whereby the pipe 2 and the pipes 1, 1 are adhered tightly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a multi-layered pipe that utilizes a shape memory effect, and particularly the present invention relates to a method of manufacturing a multi-layered pipe that utilizes a shape memory effect and has corrosion resistance. .

The shape memory effect here refers to the effect of deforming a shape memory alloy at a humidity below the M1 point and then returning it to its pre-deformed shape by heating it to a temperature above the As point. Interaction or deformation induction of site phase variants! This is an effect produced by utilizing deformation based on the growth of rutin sites and reverse transformation due to heating after deformation.

By the way, pipes used as piping, structures, or devices that are mainly used in corrosive environments are coated with a corrosion-resistant material, plated, or tactile welded on the inner or outer surface in order to impart corrosion resistance to the pipe, or A thin-walled tube of the material may be used as a multilayer tube, and the tube itself may be used as a single-layer thick-walled tube with corrosion resistance.

However, the above-mentioned conventional corrosion-resistant pipes have various problems or drawbacks as follows.

Pipes coated or painted with corrosion-resistant resin have the drawback that the environmental conditions in which they can be used are limited, and in particular the temperature range in which they can be used is narrowly limited, that is, they have poor stability against temperature. O In addition, when using plated pipes, it is difficult to obtain a uniform plating film when the pipes are long, and there are defects such as pinholes, so these pipes must be inspected. However, there is a drawback that stable performance is difficult to obtain because inspection is difficult, especially for small-diameter pipes. Furthermore, the adhesion of the plating film itself to the base material is weak, and it tends to peel off when repeatedly heated and cooled, so there are restrictions on pipes coated with these platings and used at °C due to the conditions under which they are used. strict.

In addition, for pipes that are used with metal welding,
If the pipe is a large-diameter pipe, it is advantageous because sufficient build-up welding can be performed, but it is difficult to perform sufficient build-up welding on a small-diameter pipe.

Furthermore, depending on the properties of the base metal, defects such as cracks may occur at or near the weld, and the corrosion-resistant material itself rarely has weld defects (and it is difficult to inspect these defects). Problems remain.Furthermore, it is often difficult for the overlaid corrosion-resistant material to exhibit sufficient properties if it is left welded.

In the case of a multilayer pipe in which a corrosion-resistant material is joined to a thin-walled pipe, the adhesion of the joint surface is poor, and there are problems in terms of thermal efficiency, especially when used at high temperatures.

As mentioned above, multilayer pipes manufactured by methods such as coating, plating, overlay welding, or stacking have many deficiencies in terms of performance, and therefore, although they are expensive for parts that require corrosion resistance, However, the present invention eliminates the drawbacks of the conventional method for manufacturing multi-layered pipes.*
It is an object of the present invention to provide a manufacturing method that improves the manufacturing method, and the aforementioned object can be achieved by providing the manufacturing method described in the claims. That is, the present invention provides a method for manufacturing a multi-layered tube in which a corrosion-resistant tube is fitted on at least seven of the inner and outer surfaces of a base material tube, in which an alloy tube having a shape memory effect is used as the corrosion-resistant tube. After processing and deforming the alloy tube at a temperature below the M1 point, fitting the base material tube and the alloy tube,
Next, the alloy tube is heated to a temperature of one point or more to return the alloy tube to the shape before processing deformation, thereby bringing the base material tube and the alloy tube into close contact with each other. It is something.

Next, the present invention will be explained in detail.

The present inventors have conducted various studies to eliminate and improve the drawbacks of the conventional manufacturing methods described above. As a result, it has been found that 1. By utilizing the poetic properties of shape memory alloys, it is possible to mount a base material tube and a shape memory alloy tube. The present invention was completed based on the new finding that it is possible to obtain a multilayer tube consisting of two or three layers that has very good adhesion at the contact interface when fitted.

According to the present invention, the shape memory effect of the shape memory alloy, that is, the shape change in which the tube diameter expands or contracts is utilized, and the shape memory alloy tube is superimposed on the inner and/or outer surface of the relatively inexpensive base material tube. This allows them to be brought into close contact with each other.

1st @(a) is a diagram showing a cross section when the shape memory alloy tube l is fitted onto the outer surface of the base material tube, and FIG.
1)) is a diagram showing a cross section when the shape memory alloy tube l is fitted inside the inner surface of the base material tube.

FIG. 1(c) is a diagram showing a cross section when shape memory alloy tubes 1 are fitted onto the outer and inner surfaces of the base material tube.

Next, the present invention will be explained with reference to examples.

Example Outer diameter/! of a NiTi alloy (Ti -lt, atomic % 1i1) as a shape memory alloy tube. F,! 1111 and /7
．． Two types of electron beam welded tubes were used: jwm, and the wall thickness was O9j. ◇As the base material tube, a SUS 3σ TP outer diameter/7.3 m and wall thickness -1 tube was used.

The outer diameter of NiTi alloy pipe after grinding the weld bead/jjllll
By cold drawing of l, outside diameter /Q, jm, outside diameter /7. jm by hydro-pressure molding at room temperature.
The tube was expanded to −. These two types of NiTi alloy tubes are shown in Figure 1 (
As shown in (1), the movable ring shaped It was heated sequentially by a burner. The moving speed of the burner is approximately /kO
■/mix, and the temperature of the hot water due to heating of the tube was approximately 100°C on the inner surface of the tube. Through such heat treatment, the N1 〒1 alloy tube with an outer diameter of 100 m is restored to its shape so that it tightly adheres to the inner surface of the 8US JOda TP, and the N1 alloy tube with an outer diameter of 7 g and jfm
The 111 alloy tube returned to its shape so that it was in close contact with the outer surface of the SUB JO-tei TPO.

The degree of adhesion of the thus obtained multilayer tube was examined by the following method. That is, after the NiTi alloy tube on the tube end surface and the base material tube were brazed with silver solder, a 900° bending process was performed using a conventional method. The inner bending radius at this time was SO audience. This multilayered tube was then cut into rings at various locations and the cross sections were inspected, and as a result, there was no mutual peeling at the interfaces between the layers. Further, no peeling was observed at the interfaces of each layer even in a flattening test using a conventional method.

In order to cause the deformation due to the shape memory effect, in addition to the heating by the ring-shaped burner shown in the above embodiments, various heating means such as electric induction heating, electrothermal heating, and others can be used.

Further, the part of the tube to be heated may be an annular part surrounding the pipe as in the embodiment, or may be a single point part.For example, in the case of single point burner heating, the burner or the pipe is rotated while the pipe is heated in the direction of the outer circumference of the pipe. It is desirable to heat it evenly. Furthermore, the entire length of the tube may be heated simultaneously, but in order to obtain good adhesion, it is advantageous to sequentially move the annular heating section in the longitudinal direction of the tube as shown in the embodiment.

According to the present invention, the heating temperature for making the multi-layered tubes adhere well to each other can be any temperature necessary for restoring the shape of the shape memory alloy used, and the cold pre-processing of the shape memory alloy tube can be performed after that. It does not matter how big or small the deformation is, as long as the processing is within the range where shape recovery occurs due to the heating.

The shape of the processing deformation may also be arbitrary. Further, the clearance between the base material tube and the shape memory alloy tube during fitting may be any value as long as it is within the shape recovery amount of the shape memory alloy tube.

As described above, the multilayer pipe manufactured according to the present invention can be suitably used in chemical equipment that handles warm seawater, and can also be used in applications that require low corrosion resistance.

[Brief explanation of the drawing]

Figure 1 (&) is a cross-sectional view of a single tube with a shape memory alloy tube fitted around the outer periphery of the base metal tube, and Figure 1 (b) is a cross-sectional view of a single tube with a shape memory alloy tube fitted around the inner periphery of the base metal tube. Cross-sectional view of the single-layered pipe, 1st
Figure (0) is a cross-sectional view of a triple tube in which shape memory alloy tubes are fitted to the inner and outer peripheries of the base material tube, and Figure 2 is the same as Figure 1 (,
) is a perspective view showing a state in which the triple pipe shown in FIG. l...shape memory alloy tube, c...base material tube, 3...ring-shaped burner. Patent Applicant Kawasaki Steel Corporation Representative Patent Attorney Mura 1) Politics Figure 1 (.) (b) (C)

Claims (1)

[Claims] 1. A method for manufacturing a multi-layered tube in which a corrosion-resistant tube is fitted on at least one of the inner and outer surfaces of a base material tube, in which an alloy tube having a shape memory effect is used as the corrosion-resistant tube. After processing and deforming the alloy tube at a temperature below the Ma point, inserting the processed and deformed alloy tube onto at least one of the inner and outer surfaces of the base material tube, and then A multi-layered tube characterized in that the alloy tube fitted into the tube is heated to a temperature of five dew points or higher to restore the alloy tube to its shape before being processed and deformed, thereby bringing the alloy tube into close contact with the base material tube. Manufacturing method @