JPH0576387B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a wear-resistant curved double tube in which a curved inner tube made of wear-resistant material is joined to a curved outer tube.

[Prior Art] Fluid transport of solid materials is widely used in various industrial fields, and among these fluid transport pipes, for example, slurry transporting solid materials such as coal and various ores mixed with water is used. In transport pipes or air transport pipes for powdery materials such as cement, dust, silica sand, etc., the inner surface of the pipe is likely to wear out.

In particular, the bent pipe portion is subject to significant wear, which often becomes a problem.

However, in fluid transport piping for applications where wear resistance is particularly required, piping made of materials with excellent wear resistance such as high chromium cast iron or ceramics may be used.

On the other hand, piping made of wear-resistant materials such as high chromium cast iron or ceramics has the disadvantage of being easily damaged when subjected to impact force.

In addition, since high-hardness wear-resistant materials have extremely poor weldability and workability, the first drawback is that it is impossible to attach the flange to the main body by welding.
Second, even if the flange is integrally formed, finishing and drilling are difficult, and third, repair welding is difficult.

In addition, it also has the disadvantage of high manufacturing costs.

The present inventors have previously proposed a method in which the bent outer tube is provided with high toughness, and the bent inner tube is made of a lined inner tube made of a large number of pieces of wear-resistant material. The bent outer tube is compressed by applying heating and cooling in the circumferential direction to the bent outer tube, and simultaneously and continuously in the axial direction, for example, while moving relative to the axial direction. This paper proposes a method for manufacturing a bent double pipe in which an inner bent pipe is joined to an outer bent pipe by tightening the diameter. (Japanese Unexamined Patent Publication No. 62-61733) [Problems to be Solved by the Invention] However, the above-mentioned conventional method for manufacturing a double pipe has the following problems.

1. Regularly arranging a large number of arch-shaped pieces made of wear-resistant materials and stacking them to form a curved inner tube is difficult in processing and increases processing time.

2. When reducing the diameter of the bent outer tube by applying heating and cooling, compressive force acts from the outside of the lining inner tube and is transmitted to many pieces, but because the wear-resistant material exhibits low toughness, The piece cannot resist the compressive force sufficiently, resulting in damage to the piece.

3. When fluid transport of solid materials is carried out, the inside of the bent pipe is subject to significant wear, particularly on the outside, compared to the inside. Therefore, the use of expensive pieces of wear-resistant material even in the inner part, where wear is relatively low, reduces the economic efficiency of the wear-resistant bent double pipe.

The present invention relates to an improvement on such a conventional method, which makes it relatively easy to form a bent inner tube using pieces of wear-resistant material, and prevents breakage of the bent inner tube when reducing the diameter of the bent outer tube. The object of the present invention is to provide a method for manufacturing an excellent wear-resistant bent double pipe that can prevent the wear and tear and improve economical efficiency by limiting the use of expensive wear-resistant materials to areas where wear is relatively large. .

[Means for Solving the Problems] In order to achieve the above object, the present invention inserts a bent inner tube 2 into a bent outer tube 1, performs annular heating in the circumferential direction of the bent outer tube and heats the surrounding area. Cooling is applied simultaneously, the thermal expansion of the heated part is restrained by the surrounding low temperature part to suppress the expansion diameter, and then the heated part is contracted by cooling so that the diameter of that part becomes smaller than the initial diameter. Therefore, the wear-resistant curved double-pipe tube is constructed by relatively moving the curved outer tube and the heating/cooling means in the bending direction so that the diameter of the curved outer tube after cooling is smaller than the initial diameter over the entire length of the heating section. In the manufacturing method, after forming a bent inner tube 2 in which wear-resistant material pieces 4 are arranged in a recess 5 provided on the outer surface of the outer circumferential side of the thick portion of the bent tube 3, a bent outer tube 1 is formed. The curved inner tube 2 is connected to the bent inner tube 2.

[Function] The present invention has the following effects due to the above configuration. In other words, when forming a bent inner tube, wear-resistant pieces can be adhered and regularly arranged only in the recesses provided on the outer surface of the outer peripheral side of the thick part of the bent tube. can be made relatively simple and the machining time can be shortened.

In addition, when reducing the diameter of the bent outer tube into which the bent inner tube is inserted, the thickness of the recessed portion of the bent tube is smaller than that of the other portions, so the diameter cannot be reduced. Even if the accompanying compressive force acts on the bent pipe, a minute elastic deformation is brought about, and the propagation of excessive compressive force at the contact area between the piece and the bent pipe can be alleviated. This can prevent damage to the wear-resistant material piece. In this way, a wear-resistant material with relatively low toughness can be selected and used as the material for the bent pipe. In addition, since pieces of wear-resistant material are arranged only in the recesses provided on the outer surface of the outer circumferential side of the thick part of the bent pipe, fluid transport of the solid material occurs and wear on the inner surface of the bent pipe progresses. However, even if the inner surface of the concave part, where the wear on the outer periphery is particularly abrasive, comes into contact with the highly wear-resistant piece, the service life of the wear-resistant bent double pipe can be extended. I can do it.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

Figure 1 shows the manufacturing method of a wear-resistant bent double pipe such as a slurry transport pipe, and 1 indicates a bent outer pipe, which is made of, for example, low carbon steel with a carbon content of about 0.25% and has a predetermined bending radius. are doing. Reference numeral 2 indicates a bent inner tube, and the bent inner tube 2 consists of a bent tube 3 and a piece 4 of wear-resistant material, and a recess 5 is provided on the outer surface of the outer peripheral side of the thick portion of the bent tube 3. Pieces 4 of wear-resistant material are arranged one after another on the inner surface to form a bent inner tube 2 having an outer diameter substantially approximating the inner diameter of the bent outer tube 1 .

As the bent pipe 3, for example, high chromium cast iron is used, and as the wear-resistant material piece 4,
For example, Al ₂ O ₃ ceramics, ZrO ₂ ceramics, etc. are used.

Figure 2 shows an embodiment of the wear-resistant bent double pipe,
This is illustrated by the radial cross-section in FIG. In FIG. 2, pieces 4 of wear-resistant material are bonded using, for example, an adhesive so that the side surfaces of the pieces 4 are in close contact with each other in the circumferential direction within the recess 5 of the bent pipe 3, and The outer diameter of the bent inner tube 2 at the height of the piece 4 substantially approximates the inner diameter of the bent outer tube.

The thickness t ₁ of the bent pipe 3 at the concave portion 5 is smaller than the pipe thickness t ₀ of the portion other than the concave portion 5 .

Next, in FIG. 1, the bent inner tube 2 manufactured as described above is inserted into the bent outer tube 1, set so as to be moved in an arcuate direction at a predetermined speed as shown by arrow 9, and then On the outer periphery of the bent outer tube 1, an annular heating means such as a high frequency induction heating device 6 (hereinafter referred to as a heating device) is attached, and cooling water is placed close to both sides of the heating device 6 at a predetermined distance. The annular ejection means 7, 7 (hereinafter referred to as a cooling device) are attached, and the two are integrated into a combined unit 8, with the unit 8 indicated by the arrow 1.
Move it in the arc direction so that it reaches 0.

In the process of moving the unit 8, the heating device 6 applies an expansion effect to the bent outer tube 1 at the locally heated portion of the bent outer tube 1, and cooling water is jetted from the cooling device 7 at both ends of the locally heated portion. simultaneously receives cooling action. Then, after plastic deformation is performed under the expansion action due to thermal expansion in the locally heated portion of the bent outer tube 1, cooling is performed under the cooling action due to the movement of the unit 8, and the heating is performed. The thermal expansion of the bent outer tube 1 is restrained by the surrounding low-temperature section to suppress the expansion diameter, and then the heated section is contracted by cooling and the diameter is reduced to be smaller than the initial outer diameter. A compressive stress is generated in the bending tube 2, which causes the bent inner tube 2 to be compressed from the outside. At this time, the compressive force also acts as a load on the thin wall thickness _t1 of the recess 5 of the bent pipe 3, causing elastic deformation, and displacement of the wear-resistant material piece 4 under such elastic deformation is allowed. Since the propagation of the compressive force to the contact portion of the piece 4 can be alleviated, damage due to brittle fracture or the like of the wear-resistant material piece 4 in the concave portion of the bent pipe can be prevented.

Thus, over the entire length of the bent portion of the bent outer tube 1,
The relative movement of the unit 8 is performed, and the diameter expansion by local heating and the diameter contraction by cooling of the bent outer tube 1 are performed simultaneously and continuously, and by at least one of the above operations, the bent outer tube 1 and the bent inner tube 1 are The pipe 2 is uniformly joined to the pipe 2 in the radial and circumferential directions with a strong joining force over the entire length of the bent part, thereby producing a wear-resistant bent double pipe.

Furthermore, a structure having welded flanges at both ends can be manufactured by secondary processing of a wear-resistant bent double pipe.

Due to long-term use of the wear-resistant bent double tube manufactured as described above, even if the bent tube is worn from the inside, the piece of wear-resistant material continues to be connected to the bent outer tube, reducing wear resistance. Since it can withstand the atmosphere, it exhibits abrasion resistance and slows down the progress of wear, making it possible to extend the service life compared to bent double pipes made of the same material.

In addition, if the cross-sectional inner surface of the bent inner pipe is an ellipse different from a circle, the thickness of the outer circumferential side of the bent pipe where severe wear occurs will be increased, so the life of the wear-resistant bent double pipe will be reduced. A wear-resistant bent double tube that can be further stretched and has a long service life is manufactured.

It goes without saying that the embodiments of the present invention are not limited to the embodiments described above, and various aspects such as selection of various wear-resistant materials, shapes of pieces of the wear-resistant material, formation of bent inner tubes, etc. can be adopted. .

[Effects of the Invention] As is clear from the above-mentioned embodiments, the present invention is advantageous in forming a curved inner tube by forming a recess in the outer surface of the outer circumferential side of the curved tube, which causes severe wear due to change in direction of fluid flow. By arranging the pieces of wear-resistant material only in the bend, the formation of the bent inner tube can be made much easier than in a method in which pieces are arranged around the entire circumference of the bent tube.

In addition, by using expensive wear-resistant materials with relatively high toughness only in areas where wear is relatively large, it is possible to obtain functions with higher wear resistance than conventional wear-resistant bent double pipes. It is possible to manufacture excellent wear-resistant bent double pipes that can improve economic efficiency.

Furthermore, since metallurgical joining is not used to join the curved outer tube and the curved inner tube, a practical effect is achieved in that energy consumption during joining can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a method for manufacturing a wear-resistant bent double pipe according to an embodiment of the present invention, and FIG. 2 is a sectional view in the radial direction of FIG. 1. 1... Bent outer tube, 2... Bent inner tube, 3... Bent tube, 4... Piece of wear-resistant material, 5... Recess, 6...
...Heating device, 7...Cooling device.

Claims (1)

[Claims] 1 Insert the curved inner tube 2 into the curved outer tube 1, apply circumferential annular heating to the curved outer tube and cooling the surrounding area simultaneously, and convert the thermal expansion of the heated part into the surrounding low-temperature area. The heated part is then cooled to contract so that the diameter of that part becomes smaller than the initial diameter, and the bent outer tube and the heating/cooling means are moved relative to each other in the bending direction. A method for manufacturing a wear-resistant bent double tube in which the diameter of the bent outer tube after cooling is smaller than the initial diameter over the entire length of the heating section, wherein the outer surface of the bent tube 3 is The wear-resistant curved tube 2 is characterized in that the curved inner tube 2 is formed with wear-resistant material pieces 4 arranged in a recess 5 provided in the groove 5, and then the curved outer tube 1 and the curved inner tube 2 are joined. Method of manufacturing heavy pipes.