JPS62144816A - Manufacture of dissimilar metal coated two-layer tube - Google Patents

Abstract

PURPOSE:To improve the product quality by inserting a dissimilar metal tube onto a base tube having a groove in the longitudinal direction and press fitting a part of the dissimilar metal tube corresponding to the groove into the base tube through fin rollers for forming a composite tube. CONSTITUTION:A dissimilar metal tube 1, having a somewhat larger diameter than that of a base tube 2 on which a groove 3 in the longitudinal direction is previously formed, is prepared and is inserted onto the base tube 2 to forma duplex tube 4. Then, feeding the duplex tube 4 in the longitudinal direction,the peripheral part of the tube 1 corresponding to the groove 3 is gradually fitted into the groove 3 by plural fin rollers 5A to be formed into a composite tube 6'. Next, the diameter of the tube 6' is reduced between upper and lower reducing rolls 7 and 8 to joint both the tubes 1 and 2. In this method, the joining force of the tube 6' is improved and generation of wrinkles on the surface of the tube is prevented. Therefore, the product quality is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing a multilayer pipe coated with dissimilar metals.

(Prior art and its problems) A multi-layer pipe is made by fitting a cylindrical inner layer pipe, that is, a mother pipe, and a different metal pipe as an outer layer pipe. The use of steel pipes has advantages such as improving the appearance and preventing rust, so there is demand for a wide range of uses. Generally speaking, this multilayer pipe is manufactured by separately manufacturing the main pipe and dissimilar metal pipes and fitting them together, but this method lacks adhesion between the main pipe and dissimilar metal pipes, and both pipes Since a gap is likely to occur between them, the diameter of the multilayer pipe is reduced after the above-mentioned mutual fitting. However, after the diameter reduction process, the difference in shrinkage rate between the main pipe and the redundant metal pipe of class X causes wrinkles in the main pipe or dissimilar metal pipe, leading to deterioration in quality and a decrease in the bonding strength between the inner and outer pipes. Things often happen.

(Technical Means for Solving the Problems) The present invention solves the above problems, and the technical means for this purpose is to form seven tR sections 3 in the longitudinal direction in advance at required parts of the outer peripheral surface. The dissimilar metal tube 1 is fitted onto the cylindrical main tube 2 which is recessed over its entire length, and then the portion of the dissimilar metal tube 1 corresponding to the groove 3 is inserted into the corresponding groove of the main tube 2 using a fin roller. It is formed into a cylindrical multi-layered pipe 6' by press-fitting it into the main pipe 2 and covering it in close contact with the main pipe 2.
The groove portion 3 is closed by a diameter-reducing roll 7.8 which curves around and presses the outer peripheral surface toward the center.

(Example) The method of the present invention will be explained below based on the drawings. The reference numeral 1 shown in FIG.
It is a cylindrical dissimilar metal tube such as a stainless steel tube or a steel tube with a wall thickness of about 21 mm. The dissimilar metal tube 1 is not limited to a completely endless tube; for example, it may be a stainless steel plate bent into a cylindrical shape using a roll bender and its both edges welded, or a so-called seam-stopped tube. It may also be a piece that has been bent, or a piece that has been simply bent without welding or sealing its edges.

The reference numeral 2 shown in FIG.
■It is a main pipe made of ordinary steel with a wall thickness of about 1.
A groove 3 is recessed in a predetermined portion of the outer circumferential surface of the main pipe over the entire longitudinal length of the main pipe.

First, the dissimilar metal tube 1 is externally fitted to the main tube 2.
The two main tubes 4 are fed in the longitudinal direction as shown in FIG. The three types of fin rollers 5.A, 5[1, 5C are used to gradually move the portion of the dissimilar metal tube 1 corresponding to the groove 3 of the main tube 2 into the corresponding groove 3.
While press-fitting the dissimilar metal tube I into the main tube 2, the dissimilar metal tube I is squeezed along the outer circumferential surface of the main tube 2 so that the dissimilar metal tube 1 is completely attached to the main tube 1 as shown in FIG. At this time, as a part of the dissimilar metal tube 1 is press-fitted into the groove 3, a uniform tension force is applied to the entire dissimilar metal tube 1, so the dissimilar metal tube 1 utilizes this tension force. The fin rollers strongly and reliably adhere to the main tube 2. Although seven fin rollers may be used, in this embodiment, the thickness of the rollers is gradually reduced and the rollers are gradually moved inward to the groove 3. Three fin rollers 5A, 5B, and 5C that are close to each other are arranged at appropriate intervals, and a portion of the dissimilar metal pipe 1 is gradually moved into the main pipe in stages as shown in Fig. 3+81 to (C). By press-fitting the dissimilar metal tube I into the groove 3 of the fin roller 2, the entire dissimilar metal tube I can be deformed evenly, uniformly, and reliably, and its adhesion to the main tube 2 is extremely good. may be provided in five stages.

Next, as shown in FIG. 5, the multilayer tube 6' is passed between an upper diameter reducing roll 7 and a lower diameter reducing roll 8 to reduce its diameter.

W, the inner diameter of the circular hole 9 formed by both the upper and lower rolls 7.8 is made smaller than the outer diameter of the multilayer pipe 6', and first a slight opposing gap l is provided between the upper and lower rolls 7.8. With the inner diameter of the circular hole 9 in the vertical direction equal to or slightly larger than the multilayer pipe 6'', the multilayer pipe 6'' is passed between the rotating upper and lower rolls 7.8, and as it passes, the upper and lower rolls are Finally, by bringing the upper and lower rolls 7.8 close to each other so that the diameter of the circular hole 9 is a predetermined diameter with a facing gap e of 7.8 degrees, the dissimilar metal tube 1 is tightly attached to the groove 3 of the tube 1 and this groove 3. A portion of the main pipe 2 is crushed in the direction of the arrow, and the multilayer pipe 6' is reduced in diameter to the same outer diameter as the inner diameter of the circular hole 9. As a result, a cylindrical shape is formed in which the inner and outer layers are made of different metals. A multi-layer pipe 6 is now manufactured.

Furthermore, in order to form the multilayer pipe 6 into a desired cross-sectional shape depending on the application, as shown in FIG. By going through a forming roll process that forms
For example, the multilayer 1!13 is formed into a desired shape such as a deformed ellipse.

(Results of the Invention) According to the present invention, a dissimilar metal tube is externally fitted onto a cylindrical main tube in which seven grooves are recessed in required portions of the outer peripheral surface, and then a portion of the dissimilar metal tube is fitted with a fin roller. Since the dissimilar metal pipe is tightly covered with the main pipe while being press-fitted into the groove of the main pipe, the dissimilar metal pipe is forcibly squeezed along the outer shape and outer diameter of the main pipe due to the press-fitting. , it can be tightly attached to the main pipe without any gaps.

In particular, according to the present invention, since it is only necessary to form the groove in the outer circumferential surface of the main pipe, the main pipe can be manufactured very easily, and the manufacturing equipment for multilayer pipes can also be simplified. I can,
In addition, the materials for each of the main tube and dissimilar metal tube forming the multilayer tube can be kept to a minimum. Furthermore, unlike the conventional method, the diameter of the main tube and dissimilar metal tube is not reduced integrally to induce a state of close contact between the two tubes. A beautiful multi-layered pipe can be obtained with no wrinkles, no q, II separation, or space between the mother pipe and the dissimilar metal pipe, and with flat inner and outer surfaces h.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and include FIG. 1(a),
fbl is an external perspective view of a dissimilar metal tube and a main tube used in the manufacturing process of the present invention, FIG. 2 is a perspective view showing a state in which a dissimilar metal tube is fitted onto the main tube to form a 2Tfi tube, FIG. 3 (a
l, (bl, tel are cross-sectional views showing the state in which it is formed by fin rollers, Figure 4 is a cross-sectional view of a multilayer pipe manufactured by fin rollers, and Figure 5 is a view in which it is formed by diameter-reducing rolls. Cross-sectional view, FIG. 6 is a cross-sectional view showing a state in which the cross-section is formed into an elliptical shape by forming rolls. 1... Different metal tube, 2... Main tube, 3... Groove, 4
...double pipe, 5A+ 5B, 5C...fin roller,
6°, 6...multilayer pipe, 7,8...diameter reducing roll. Applicant: Asada Boming Co., Ltd. Figure 5 Figure 6

Claims (1)

[Claims] A dissimilar metal tube is fitted onto a cylindrical main tube which has a single groove formed in advance over the entire length in the longitudinal direction at a predetermined portion of the outer peripheral surface, and then a fin roller is used to fit the dissimilar metal tube into the groove of the dissimilar metal tube. A cylindrical multi-layer pipe is formed by press-fitting the corresponding part into the groove of the main pipe and closely covering the main pipe, and then surrounding the multi-layer pipe and extending the outer circumferential surface toward the center. A method for manufacturing a multilayer pipe coated with dissimilar metals, in which the groove is closed by a pressing diameter-reducing roll.