JPS61284325A - Double pipe manufacturing method - Google Patents

Abstract

PURPOSE:To make it possible to perform relative layering, cutting, and right junctioning at once in one process of relative layering by relatively layering both the external and internal pipes cutting at least one of the inner and outer surfaces of the respective pipes. CONSTITUTION:A hard cutting blade 3 for the inner surface of an external pipe 1 is formed into ring shape and connected in a body with a cutter 4 formed into a concavity in its moving direction. Then, when the cutter 4 is relatively advanced through a means such as a rod or the like after their concentrical alignment in relation to the rear end of the external pipe 1, the cutting blade 3 of the cutter 4 is advanced cutting the inner surface of the external pipe 1. The internal pipe 2 connected with the cutter 4 in a body, therefore, is relatively layered in succession on the cut inner surface of the external pipe 1 with the outer surface being junctioned tightly. Concequently, being revealed as the metallic newborn surface of carbon steel, the cut inner surface of the external pipe 1 is immediately junctioned tightly in succession to the outer surface of the internal pipe 2.

Description

[Detailed Description of the Invention] <Industrial Application Field> The disclosed technology provides a heat-resistant,
It belongs to the technical field of manufacturing double pipes that have corrosion resistance, wear resistance, etc.

Accordingly, the invention of this application provides a double tube with tight fitting, in which an outer tube made of carbon steel or the like and an inner tube made of stainless steel or the like are joined in-kind to closely join the inner surface of the outer tube and the outer surface of the inner tube. The invention relates to a manufacturing method, and in particular, in the process of relatively overlaying the outer tube and the inner tube, one of the inner surface of the outer tube and the outer surface of the inner tube at the same time as the layering,
Alternatively, while cutting all opposing surfaces, both are moved relative to each other in the axial direction to closely join the cut new surfaces, and further, in the close joining process, one of the diameter of the outer tube is increased and the diameter of the inner tube is decreased, Alternatively, the invention relates to a method for manufacturing a double pipe in which both methods are performed to form a tight fit through tight joints.

<Prior Art> As is well known, piping is widely used in various fields, but it is important to have sufficient strength as piping and pressure resistance, as well as heat resistance and corrosion resistance as a function of piping under severe conditions. It is necessary to have properties such as durability and abrasion resistance.
Since a single pipe cannot satisfy all the functions depending on the material, the material is selected according to the function, for example, the outer pipe is pressure resistant and the inner pipe is corrosion resistant and wear resistant. So-called double pipes are increasingly being used.

Therefore, due to manufacturing technology and cost considerations, close-fitting double pipes such as self-sealing double pipes have come to be used in place of so-called clad pipes. By relatively overlapping the outer tube and the inner tube manufactured in a specified manner, the shrink fitting method, the hydraulic tube expansion method, the heat expansion method as disclosed in many of the applicant's earlier inventions, or the diameter reduction method, etc. Manufactured.

Generally, the raw tubes that make up the outer tube and the inner tube have rough dimensional tolerances, and therefore, in the double tube manufacturing process, it is essential that the outer tube and the inner tube be closely joined to meet the required strength. I'm trying to get it.

<Problem to be solved by the invention> ′□゛: Therefore, among the above manufacturing methods, the shrink fit method requires high-precision cutting in advance on the joining surface of the double pipe and the inner pipe at the stage of the blank pipe. In addition, the hydraulic pipe expansion method has the disadvantage that it is extremely difficult to control the accuracy of machining, and it is difficult to manufacture long pipes. The disadvantage is that there is no freedom in selecting the tube material because of the need for tube expansion, and the thermal expansion method has the same limitations in material selection and has the disadvantage that heat management is extremely cumbersome. Contrary to the above, there was the inconvenience of material limitations due to the plastic deformation of the outer tube.

However, as mentioned above, with these methods, since the outer tube and inner tube are prepared in advance at the woodwind stage, corrosion may occur on the joint surface of the two, and it is difficult to closely join the double tube during the manufacture of the blank tube. There was a negative point that the time gap was too large.

The purpose of this invention is to have the potential advantages of a self-contained double pipe without limitations in material selection based on the prior art described above;
As a result, it is assumed that the outer tube and inner tube are layered relative to each other during welding, and the outer tube and inner tube are not necessarily made into a double tube when they are fitted, but rather the relative layering of both. Sometimes, cutting is applied to the joining surfaces at the same time to automatically create close bonding through the new metal surface, making it possible to perform cutting, relative overlapping, and close bonding all at once in one process, and to achieve sufficient It is an object of the present invention to provide an excellent method for manufacturing double pipes that can provide a tight fit, reduce the number of steps, and reduce costs, thereby benefiting piping applications in various industries.

<Means/effects for solving the problem> In order to solve the above-mentioned problem, the structure of the invention of this application, which is based on the scope of the above-mentioned patent claims, is to solve the above-mentioned problem. and an outer tube with a design minimum inner diameter than the diameter of the closely joined surface of the inner tube, an inner tube with a slightly larger outer diameter, and a heat-resistant,
Select according to properties such as corrosion resistance, abrasion resistance, pressure resistance, etc., and simultaneously bond the inner joint surface of the outer tube to the outer joint surface of the inner tube, or both at the same time when the two are layered relative to each other. While performing the cutting process on the surface, the relative progress in the axial direction is performed to relatively overlap the two metal surfaces, and the newly formed metal surface exposed by the cutting process is used to ensure tight bonding without exposure to the outside air. This technology uses a multi-layer process to increase the diameter of the outer tube and reduce the diameter of the inner tube, so that when the relative fitting is completed, the two are tightly joined and self-tightened. be.

<Embodiments - Configuration> Next, embodiments of the invention of this application will be described below based on the drawings.

The basic embodiment shown in FIG. 1 is a mode of manufacturing a wear-resistant double pipe, and the outer pipe 1 made of carbon steel has the same inner diameter as the outer pipe and the inner diameter of the double pipe. ! It is roughly manufactured with an inner diameter that is set to be smaller than the diameter of the bonded curved surface, and the ceramic inner tube also has an outer diameter that is set to be larger than the diameter of the closely bonded surface between the outer tube and the inner tube. Therefore, the outer tube 1 and the inner tube 2 may be manufactured separately and stored in open piles or the like.

In the double tube manufacturing process, as shown in the figure, a high-hardness cutting edge 3 is formed on the inner surface of the outer tube 1 in the shape of a ring at the tip of the inner tube 2, and is concave in the direction of movement. The formed cutter 4 is integrally connected to the cutter 4 by an appropriate means, and after the cutter 4 is concentrically aligned with the rear end of the outer tube 1 by means such as a rond, relative movement is performed as shown by the arrow. When the cutter 4 is cut, the cutting blade 3 of the cutter 4 advances while cutting the inner surface of the outer tube 1, so that the inner tube 2, which is integrally connected to the cutter 4, tightly contacts the cut inner surface of the outer tube 1 with its outer surface. As they are joined, they are layered relative to each other.

Therefore, when the cut inner surface of the outer tube 1 is exposed as a new metal surface of carbon steel, it is immediately closely bonded to the outer surface of the inner tube 2, and as a result, the outer tube 1
On the other hand, for the inner tube 2, relative overlapping, cutting, and close bonding are performed in one process.

Therefore, in the initial preparation process, as long as the outer surface of the inner tube 2 accurately matches the outer diameter of the cutting blade 3 of the cutter 4, the close joint surfaces of the outer tube 1 and the inner tube 2 can be automatically joined with high precision. become.

Incidentally, when the outer tube 1 and the inner tube 2 are cut and layered relative to each other, the cutting waste on the inner surface of the outer tube 1 by the cutter 4 is appropriately discharged from the tip of the outer tube 1 through the internal hole of the outer tube 1. However, in a specific embodiment, the cutting waste 6 is automatically discharged by gravity by cutting the outer tube 1 and the inner tube 2 while tilting them forward in the axial direction and rotating them. It becomes like this.

Thus, the double tube obtained in this way is the outer tube 1.
The inner tube 2 is tightly fitted to the inner tube 2 by the tight joint surface 5, and if the tight joint surface 5 is given a self-tightening effect and compressive stress is applied, the corrosion resistance can be further improved. However, as a means for this purpose, there is an example shown below.

That is, in the embodiment shown in FIG. 2, the expander 1 is advanced in advance of the cutter 4 via a radial ring support, etc., so that the expander 7 can advance the outer tube before the cutter 4 passes. 1 is increased in diameter to expand the cut inner surface of the outer tube 1 by the cutter 4, and after the inner tube 2 is stacked relative to each other, the outer tube 1 is tightly fitted to the inner surface of the inner tube 2 due to the elastic return difference. In the mated state, the inner tube 2 is tightly joined, and due to its elastic return, compressive stress can be applied to the inner tube 2, and corrosion resistance can be imparted in addition to abrasion resistance.

The discharge of the cutting layer 6 from the tip of the outer tube 1 by the cutting blade 3 of the cutter 4 is forwarded from the gap of the ring support of the expander 7 through the inner hole of the outer tube 1, so there is no problem. .

In the embodiment shown in FIG. 3, prior to cutting the inner surface of the outer tube 1 with the cutter 4, a heating means 8 is suitably mounted on the outer surface of the outer tube 1, thereby increasing the diameter of the outer tube 1. is given, the inner surface is cut by the cutter 4 in the increased diameter state, and the outer tube 1 is cooled to a predetermined level after the relative stacking of the inner tube 2 with respect to the outer tube 1 is completed, so that the outer tube 1 is contracted as described above. The inner tube 2 has a tight fit with the inner tube 2, and therefore, the two tubes are tightly joined at their joint surfaces.As in the above embodiment, the inner tube 2 has not only wear resistance but also wear resistance. Great corrosion resistance will be provided.

In addition, as an equivalent example of this embodiment, instead of increasing the diameter of the outer tube 1 by heating, the inner tube 2 is reduced in diameter by cooling, and the diameter is increased by heating after relative stacking, so that the outer tube 1 is similarly tightened. Close contact can be achieved by fitting.

Of course, it is also possible to increase the diameter of the outer tube 1 and reduce the diameter of the inner tube 2 before cutting the inner surface of the outer tube 1 with the cutter 4.

In addition, instead of the above-mentioned tightening fitting in which the diameters of both tubes are increased and contracted by heating and the elastic return differential is used, tight fitting can also be carried out by mechanical means shown in FIG. In the cutting process of the tube 1, by applying an axial compressive force F to the outer tube 1 and an axial tensile load [to the inner tube 2, the diameter of the outer tube 1 increases and the inner tube 2 is reduced in diameter, and together with each other, the fitting is performed smoothly when the two pipes are relatively stacked, and after the relative stacking, both pipes are tightly fitted due to the difference in elastic return, and compressive stress is applied to the inner pipe 2. Under load, the function can be improved by tight bonding 2.

Of course, in this embodiment, either the axial compressive load may be applied to the outer tube 1 or the axial tensile load may be applied to the inner tube 2.

In each of the above-mentioned embodiments, when the two tubes are fitted together, a clearance is temporarily formed between the inner surface of the outer tube 1 and the outer surface of the inner tube 2 when the two tubes are mutually stacked, and an oxide film is formed there due to the intrusion of outside air. However, as an embodiment to prevent this, as shown in FIG. 5, the inner tube 2 is
A cutter 4 which has previously cut the inner surface of the outer tube 1 to a predetermined depth is fixed integrally to the tip of the cutter 4 by being screwed together, and a ring-shaped cutter 4 which has previously cut the outer surface of the inner tube 2 to the rear end of the outer tube 1 projects in the rear direction. A cutter 4' having a ring-shaped cutting blade 3' is similarly fixed integrally by screwing, etc., and as shown in the figure, when the two pipes are concentrically stacked relative to each other, the inner pipe 2 is cut by the cutter 4 that connects the tip of the inner pipe. cutting the inner surface of the outer tube 1, and at the same time cutting the outer surface of the inner tube 2 with a cutter 4' fixed to the rear end of the outer tube 1;
In both cases, since the new cutting surfaces of both are in close contact with each other, the tight joining surface 5 is a close contact between the new metal surfaces, and the new metal surface formation is in a state of being cut off from the outside air, so that no oxide film or the like is formed. Immediately after the cut surfaces are formed, the two are closely bonded, and since the double layered pipes are closely bonded with the cut surfaces mutually, a diffusion bonding process can be performed in the subsequent process. A strong metallurgical bond between the outer tube 1 and the inner tube 2 is ensured.

It should be noted that the embodiments of the invention of this application are of course not limited to the above-mentioned embodiments, and the inner tube is not limited to ceramic.
Stainless steel or the like can also be used, and there is an extremely high degree of freedom in selecting the material for the outer tube.

It is also possible, of course, to rotate the outer tube and the inner tube relative to each other when they are stacked relative to each other.

Furthermore, depending on the application, it is possible to manufacture not only double pipes but also double pipes such as triple pipes and quadruple pipes. Therefore, in the invention of this application, double pipes are considered to be triple pipes or more double pipes. Of course, they are equal.

<Effects of the Invention> According to the invention of this application, there is an excellent effect that the joint surfaces of the outer pipe and the inner pipe are tightly joined in the production of double pipes etc. that basically have wear resistance. In addition, when the two tubes are layered relative to each other, either the inner surface of the outer tube, the outer surface of the inner tube, or both are joined through the new metal surface by cutting at the same time as the relative layering process, so the joining surface of both tubes is There is no need for pre-cutting based on the high precision dimensions of This results in extremely reduced work efficiency and cost reduction.

In addition, since a new metal surface is formed on the closely joined surface and the bonding is performed, an excellent effect is achieved in that formation of an oxide film or the like due to outside air is suppressed.

In addition, by increasing the diameter of the outer tube or reducing the diameter of the inner tube, or both, in conjunction with the cutting of the close joint during relative overlapping, compressive stress is applied to the outer tube and the inner tube, which improves corrosion resistance. It also has the excellent effect of improving sexual performance.

Furthermore, the friction when the outer tube and the inner tube fit together during relative overlapping is reduced, and an excellent effect is achieved in that relative overlapping is facilitated.

In addition, an excellent effect was achieved in that a tight fit with a close contact was obtained due to the elastic layer between the rain holes, and an excellent effect was achieved in that misalignment and implosion between the rain holes and the like during product operation were prevented. Ru.

By cutting the inner surface of the outer pipe and the outer surface of the inner pipe at the same time, the tight joint between the rain pipes is made on the newly formed metal surface, allowing for diffusion bonding in the subsequent process, resulting in a strong bond between the two pipes. The effect of being able to obtain this is also achieved.

[Brief explanation of drawings]

The drawings are detailed explanatory views of the invention of this application.
The figure is a cross-sectional view of the process of relative overlapping of the outer tube and inner tube, cutting, and providing a close bond. 1...Outer tube, 2...Inner tube, 5...Tight joint surface

Claims (2)

[Claims] (1) In a double-pipe manufacturing method in which the opposing surfaces of both tubes are closely joined together by assembling the outer tube and inner tube, at least one of the inner surface of the outer tube and the outer surface of the inner tube is cut while the two tubes are layered relative to each other. A double tube manufacturing method characterized by: (2) In a double-pipe manufacturing method in which the opposing surfaces of the outer tube and the inner tube are closely joined together by actually aligning the outer tube and the inner tube, the inner surface of the outer tube is A method for manufacturing a double tube, characterized in that at least one of the outer surfaces of the inner tube and the outer surface of the inner tube are cut, and the two tubes are layered relative to each other.