JPS6154990B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a method of manufacturing a double tube having a wear-resistant ceramic tube on the inside and a tough metal tube on the outside.

Although such double pipes have many uses, such as devices for transporting powder and granules such as lime, they are currently only made using the brazing method, making it difficult to select an appropriate brazing agent. However, long pipes have the disadvantage that brazing is complicated and the resulting product is not stable, that is, the adhesive strength varies depending on the location. By the way, the reason why it has been difficult to apply this type of double pipe manufacturing method even though there is a shrink fitting method for manufacturing double pipes is that the shrink fitting method has extremely limited dimensions for the two pipes that are fitted together. It was difficult to achieve such precise dimensions with ceramic pipes, which have poor machinability.
Ceramic pipes in particular have poor toughness, so if they are tightened too much, they will break, and the fact that more accurate dimensions are required than in the case of ordinary metal pipes makes the above fact even more concrete.

The present invention aims to provide a method for solving the above-mentioned problems, and its gist is to make the outer circumferential surface of a ceramic tube a rough surface having many irregularities, and then to apply a sprayed metal layer on the rough surface. The outer circumferential surface of the thermal sprayed layer is finished to a predetermined dimension, while a separately prepared metal outer tube is heated and expanded to a required temperature, and is shrink-fitted to the ceramic tube provided with the thermal sprayed layer. This is a method for manufacturing a double pipe.

The metal tube and ceramic tube of the present invention may be open at both ends or only at one end, and can be adapted to any shape such as a tapered shape or a flange. be.

The method of the present invention will be described in detail below with reference to the drawings.
First, a ceramic tube 1 whose outer circumferential surface is roughened with many irregularities by processing at the same time as its manufacture or after its manufacture, and a metal outer tube 2 to be joined to its outer circumference are prepared. If the relative size (diameter) of the ceramic tube 1 and the metal outer tube 2 is such that the ceramic tube 1 can be loosely inserted into the metal outer tube 2, stricter conditions are necessary. isn't it. Next, double pipes are manufactured in the order shown in FIG. 1, A, B, C, and D. That is, a metal sprayed layer 3 is applied to the outer circumferential surface of the ceramic tube 1 (see FIG. 1A) having a rough outer circumferential surface as described above.
It is applied to a thickness that is larger than the inner diameter when heated and expanded (see Figure 1B). In this case, the sprayed layer 3
is sufficiently bitten into the uneven portion forming the rough surface of the ceramic tube 1, and as shown in FIG. 2, the two are firmly connected to each other. Next, calculate the shrink fit allowance determined by the material and size of the metal outer tube 2, and grind and/or polish the sprayed layer 3 until it has an outer diameter that exactly matches it (see Figure 1 C). A desired double tube can be obtained by fitting the ceramic tube 1 into the heated and expanded outer tube 2 (see FIG. 1D) and then cooling it.

Note that the ceramic tube 1 may be fitted into the metal outer tube 2 and the entire body may be heated again before it cools down or after it has been cooled to diffusely bond the metal sprayed layer 3 and the metal outer tube 2 to further increase the adhesive strength. There is also.

As described above, according to the method of the present invention, a metal sprayed layer with good subsequent workability is formed on the outer periphery of a ceramic tube, which has poor workability and is difficult to finish with accurate dimensions. Because it is formed with unevenness and strong adhesion,
After that, it can be processed to dimensions that fully match the shrink-fitting allowance, and combined with the unevenness at the tip, a sufficiently reliable double tube can be made by shrink-fitting, which is a relatively simple method. It is something that can be created. Furthermore, in the present invention, even if the metal sprayed layer becomes too tight during shrink fitting, it acts as a kind of buffer material and prevents the ceramic tube from cracking.

[Brief explanation of the drawing]

Figures 1A to 1D are process diagrams of the method of the present invention, respectively.
FIG. 2 is an enlarged view of the main parts explaining the method of the present invention. In the figure, 1: ceramic tube, 2: metal outer tube, 3:
Metal sprayed layer.

Claims (1)

[Claims] 1. The outer circumferential surface of the ceramic tube is made into a rough surface with many irregularities, and then a metal sprayed layer is formed on the rough surface, and the outer circumferential surface of the sprayed layer is finished to a predetermined dimension, while a separately prepared metal outer tube is A method for manufacturing a double-walled pipe, which comprises heating and expanding the double-walled pipe to a required temperature and shrink-fitting the double-walled pipe with the ceramic pipe provided with the thermal sprayed layer.