JPS61284326A - Double pipe manufacturing method - Google Patents

Abstract

PURPOSE:To make it possible to connect accurately an external pipe and an internal pipe in a body by proliferatively junctioning both pipes after tightly junctioning them by way of relative layering cutting at least one of the inner surface of the external pipe and the outer surface of the internal pipe. CONSTITUTION:In order to form the junction faces of an external pipe 1 and an internal pipe 2, a cutter 4' with a cutting blade 3' formed into ring shape facing forward is drawn forward with a rod being faced to the rear end of the external pipe 1 concentrically. Then, a cutter blade 3 of which the inside is formed into ring shape and projected facing behind is firmly connected to the rear end of the external pipe 1 in a body and the internal pipe 2 is pushed concentrically into the pipe 1. And, drawn further forward through the rod, the cutter 4' at the end of the internal pipe 2 cuts concentrically the inner surface of the external pipe 1, and the cutter 4 connected to the rear end of the external pipe 1 also cuts the outer surface of the internal pipe 2 making both pipes perform relative movement in axial direction. The metallic newborn surface of the inner peripheral surface of the external pipe 1 by the cutter 4' and that of the outer peripheral surface of the internal pipe 2 are, therefore, proliferatively junctioned.

Description

[Detailed description of the invention] <Industrial field of application> The disclosed technology belongs to the field of manufacturing technology in which the outer tube and the inner tube of a double tube having wear resistance are closely joined metallurgically. °ru

Therefore, the invention of this application is a wear-resistant, etc., structure in which an outer tube made of carbon steel or the like and an inner tube made of stainless steel or the like are metallurgically joined at the time of physical assembly of the two. This invention relates to a method for manufacturing a double-walled tube, and in particular, when the outer tube and the inner tube are layered relative to each other, the inner surface of the outer tube and the outer surface of the inner tube are mutually cut, and further, the cutting The two outer tubes and inner tubes are integrally joined by diffusion bonding after cutting them under an inert gas atmosphere such as nitrogen gas and closely joining them by layering them relative to one another. Heavy pipe! This invention relates to an FJ manufacturing method.

<Prior art> As is well known, piping is used in all industries,
Because the installation conditions of piping vary, it is impossible for a simple single pipe to satisfy all the functions of pressure resistance, heat resistance, corrosion resistance, and wear resistance. Double pipes in which corrosion resistance is controlled by the inner pipe are becoming widely used.

Therefore, since the functions of the outer tube and the inner tube are different, a manufacturing method is adopted in which the outer tube and the inner tube, which are separately manufactured in advance, are joined together to form a double tube. There are mating pipes that are mechanically joined as separate parts, and clad pipes where the joint surfaces of the two are closely joined metallurgically. In order to deal with the stress that is applied to the outer pipe and the inner pipe due to severe conditions such as stress that can cause peeling, it is extremely important to have a strong bond between the two, and it is important that the strength of the pipe itself is controlled. This is something that cannot be ignored.

Therefore, in order to improve the strength of piping through a strong connection between the outer pipe and the inner pipe, clad pipes, etc., in which the closely joined surfaces of the two are metallurgically integrated, are better than the above-mentioned fitted pipes. There may be better installation conditions.

The manufacturing method for such rad tubes includes the so-called hot extrusion method, in which a die is installed for the outer tube of a double tube billet as a raw material, and a mandrel is installed for the inner tube, and a piston is used to produce the rad tube. There is also a method in which a clad double pipe is obtained by applying an extrusion action to a double pipe billet.

<Problems to be Solved by the Invention> However, the manufacturing of double pipes by the hot extrusion method has the advantage of high cost due to the need for large press equipment and high power. In addition, there is a drawback in terms of elasticity due to limitations on the materials used to achieve metallurgical bonding between the outer tube and the inner tube, and furthermore, the metallurgical bonding of the joint surfaces of the resulting clad tube is insufficient. There is a difficulty that
Moreover, there is also the disadvantage that accuracy control in the extrusion process is complicated.

The purpose of the invention of this application is to solve the problem of the clad double tube, which requires severe manufacturing conditions, despite the strong latent demand based on the above-mentioned prior art, and to solve the problem of the diffusion bonding of the outer tube. This diffusion bonding is achieved by simultaneously cutting the joint surface between the outer tube and the inner tube when the outer tube and the inner tube are relatively stacked to obtain a high-precision bond between the outer tube and the inner tube. The purpose of this invention is to provide an excellent method for manufacturing double pipes that is beneficial to the field of piping technology used in various industries.

<Means/effects for solving the problems> In order to solve the above-mentioned problems, the structure of the invention of this application, which is based on the scope of the preceding patent claims, is to achieve a certain pressure resistance and abrasion resistance. An outer tube and an inner tube having the functions of the above are manufactured and prepared separately in advance, and when manufacturing a clad double tube using both, the outer tube is given an inner diameter smaller than the diameter of the joint surface of both, In addition, the inner tube is given a larger outer diameter, the inner surface of the outer tube is cut, and the outer surface of the inner tube is also given a cutting action, allowing the two to pass relative to each other in the axial direction, thereby cutting the metal formed by both. The new metal surfaces are cut without being exposed to the outside air or actively under an inert gas atmosphere such as nitrogen gas to form relative layers, and the two new metal surfaces are completely bonded, and then the second metal surface is cut. A technical measure was taken in which the double tubes were diffusion bonded at IK temperature and high pressure, and the atoms of both tubes were diffused into the closely joined surfaces of both tubes to obtain a strong rad double tube.

<Embodiment - Configuration> Next, an embodiment of the present invention will be described below based on the drawings.

In the embodiment not shown in FIG. 1, 1 is an outer tube made of carbon steel, while 2 is an inner tube made of stainless steel, each of which is manufactured separately in advance as a blank tube, and the inner diameter of the outer tube 1 is The inner diameter of the inner tube 2 is previously formed to be smaller than the diameter of the joint surface of the two, and the outer diameter of the inner tube 2 is formed to be larger than the diameter of the joint surface.

It is sufficient that the inner surface of the outer tube 1 and the outer surface of the inner tube 2 are rough.

Therefore, when manufacturing a double tube, a cutter 4 is used, which has a ring-shaped cutting edge 3'' facing forward (to the left in the figure) that forms the joint surface between the outer tube 1 and the inner tube 2. ′ facing the rear end of the outer tube 1 concentrically and pulling it forward with a rond, the cutting blade 3′ of the cutter 4′ cuts the inner surface of the outer tube 1 and enters into the specified position. By connecting and integrally fixing the cutting blade 3, which has a ring shape on the inside and projects toward the rear, to the rear end of the outer tube 1, and pushing the inner tube 2 concentrically, The outer circumferential surface of the tip is cut, and then the tip of the inner tube 2 is also integrally fixed to the corresponding cutter 4' by screwing or other means, and when the state as shown in FIG. 1 is reached, the cutter 4' By pulling forward through the rod, the cutter 4' at the tip of the inner tube 2' cuts the inner surface of the outer tube 1 concentrically, and the cutter 4' connected to the rear end of the outer tube 1 cuts the inner surface of the outer tube 1 concentrically.
Cutting is performed on the outer surface of the inner tube 2, and by moving the two relative to each other in the axial direction, the new metal surface of the inner circumferential surface of the outer tube by the cutter 4' and the cut surface of the outer circumferential surface of the inner tube 2 by the cutter 4 are separated. The new metal surface is tightly bonded to each other, and
Diffusion bonding is performed immediately without exposure to outside air.

Therefore, in this process, the inner and outer circumferential surfaces of the outer tube 1 and the inner tube 2 are layered simultaneously.

Therefore, the relative overlapping of the outer tube 1 and the inner tube 2, cutting of the new metal surface, and diffusion bonding of the new metal surface are performed in one process.

During this time, the cutting waste on the inner surface of the outer tube 1 is discharged forward from the hole 7 of the outer tube 1.

In this way, as shown in FIG. 2, the joining surfaces 5 of the outer tube 1 and the inner tube 2 are brought into close contact by closely joining the new metal surfaces of the two to each other.

In this way, the double-walled material tube 8 is formed.

Once the material tube 8 is formed, as shown in FIG. tube 1
A heater 11 is disposed on the outside of the material tube 8 to provide a heating effect, and high pressure gas is supplied from the high pressure gas supply hole 10 to apply high temperature and pressure to the material tube 8, whereby diffusion bonding is performed and the outside is bonded. Close contact surface 5 between the inner surface of the tube 1 and the outer surface of the inner tube 2
At this step, atoms are diffused to form a strong metallurgical bond to obtain the desired clad double tube.

In addition, in cutting to form a new metal surface on the close joint surface 5 in dividing the seed clad double pipe, as shown in FIG. 4, a cutter 4' is integrally connected to the tip of the inner pipe 2 and moved relative to The inner surface of the outer tube 1 is cut to form a vM@joint 5' between the new metal surface and the outer surface of the inner tube 2, and then, as shown in FIG. Diffusion bonding may also be performed.

Of course, in this embodiment, the cutting action may be applied only to the outer surface of the inner tube 2 to form a new metal surface, and then the post-diffusion bonding may be performed.

It goes without saying that the embodiments of the invention of this application are not limited to the above-mentioned embodiments; for example, in the cutting process in which the outer tube and the inner tube are relatively stacked, the two may be rotated relative to each other; The diameter of the outer tube 1 is increased and the diameter of the inner tube 2 is decreased relative to either or both of the outer tube and the inner tube, thereby imparting a self-tightening effect to the state of the material tube 8, thereby bringing the two closer together. After forming the bonded state, diffusion bonding may be performed.

As shown in FIG. 4, when cutting the inner surface of the outer tube with the cutter 4', an inert gas 12 such as nitrogen gas is supplied to the inside of the outer tube and cutting is performed under the pressure to form a close bond. It may also be possible to prevent the formation of an oxide film on the surface.

Furthermore, regarding the selection of materials for the outer tube and the inner tube, materials can be freely selected and combined according to their respective functions.

<Effects of the Invention> As described above, according to the invention of this application, basically, when manufacturing a clad double pipe by tightly joining an outer pipe and an inner pipe,
By exposing the new metal surface at the same time as the relative overlapping of the two, and immediately bonding the two in close contact without exposing them to the outside air,
Since the newly formed metal surface of at least one of the outer tube and the inner tube can be brought into close contact with the other, the subsequent diffusion bonding can be performed with high precision, and an excellent effect can be achieved in that the cladding of both can be integrated.

Therefore, diffusion bonding can be performed with high precision, which means that the outer pipe and inner pipe can be integrally connected with high precision, and the resultant double pipe has the effect that no axial misalignment or circumferential misalignment occurs during operation. This has the excellent effect of ensuring strong integration as a double pipe.

Furthermore, by supplying an inert gas such as nitrogen gas to the inner hole of the outer tube and performing cutting when the outer tube and inner tube are relatively stacked, the new metal surface due to the cutting comes into contact with the outside air and forms an oxide film, etc. Qin has the excellent effect of eliminating fear.

Therefore, there is an effect that the quality of the double-walled pipe obtained in the case of M is significantly improved.

Further, since the relative overlapping and cutting are performed in one process, there is no need for large-scale equipment, and excellent effects are achieved in that the molding power is hardly large.

[Brief explanation of drawings]

The drawings are detailed explanatory diagrams of the invention of this application, in which Fig. 1 is a schematic vertical sectional view of one embodiment, Fig. 2 is a partial sectional view of a double pipe material pipe, and Fig. 3 is a schematic diagram of diffusion bonding. 4 is a sectional view of another embodiment equivalent to FIG. 1. 1...Outer pipe, 2...Inner pipe, 5.5'...Joint surface

Claims (2)

[Claims] (1) In a double-pipe manufacturing method in which the opposing surfaces of both tubes are metallurgically joined by physically matching the outer tube and inner tube, the two tubes are layered relative to each other while cutting at least one of the inner surface of the outer tube and the outer surface of the inner tube. A double pipe manufacturing method characterized in that both pipes are closely joined together and then diffusion joined. (2) In a double-pipe manufacturing method in which the opposing surfaces of both tubes are metallurgically joined by physically fitting the outer tube and the inner tube, at least one of the inner surface of the outer tube and the outer surface of the inner tube is cut under an inert gas. A double pipe manufacturing method characterized in that both pipes are laminated relative to each other and closely joined, and then both pipes are diffusion joined.