JPS62153689A - Pipe of material difficult to be worked and manufacture thereof - Google Patents

Abstract

PURPOSE:To manufacture the title pipe under simple steps and at low cost without undergoing limitations in configuration dimension and the like of the pipe by forming the outer wall member of a pipe having a complicated shape such as a porous pipe, a finned pipe or the like by a flame coating layer. CONSTITUTION:The end portions 2a-2d of a diaphragm member 2 are connected to each other and fixed by supporters 4a-4d, respectively, so as to make a base body for forming an outer wall member. The outer peripheral surface of the base body corresponds to the inner peripheral surface of the outer peripheral member. As materials constituting supporters 4a-4d, metals having low melting points such as Cu, Al and the like or inorganic compounds easily pulverized such as gypsum and the like, are employed. The outer wall member 1 made of a material difficult to be worked is formed by applying a flame coating process to the outer surface of the base body consisting of the diaphragm member 2 and supporters 4a-4d. In this step, an ordinary flame coating process carried out under a normal pressure may be applied but it is carried out especially in an inert gas atmosphere of a low pressure. The outer wall member 1 made of a flame coating layer of the material difficult to be worked is formed in a predetermined thickness, and thereafter the supporters 4a-4d may be eliminated if necessary.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a pipe made of difficult-to-process materials and a method for manufacturing the same, and more particularly, to a pipe made of difficult-to-process materials, such as a perforated pipe, a finned pipe, and a long pipe thereof. The present invention relates to a complex-shaped pipe that is extremely difficult to manufacture, and a method for manufacturing the pipe at low cost by two steps in a cylinder.

[Technical background of the invention and its problems I] In recent years, high melting metals such as tungsten (W) and molybdenum (M
There is an increasing demand for members with complex shapes made of high melting point metals such as tantalum (Ta) and niobium (Nb).

Specifically, heat exchange pipes made of W or MO can be mentioned. In other words, for heat exchange pipes,
In order to improve heat exchange efficiency, it is common practice to increase the inner surface area of the pipe as much as possible by creating a structure with a wall member that protrudes into the space inside the pipe, such as a perforated pipe or a finned pipe. It is true.

When manufacturing such heat exchange pipes, since the high melting point metals mentioned above are difficult to process, it is necessary to manufacture a metal block using powder metallurgy or melting methods, and then introduce various processes such as forging and wire drawing. Therefore, it was necessary to improve these mechanical properties. Therefore, there arises an inconvenience that the manufacturing cost increases.

Furthermore, when processing these difficult-to-process materials into the complex shapes mentioned above, the deformability of these materials is extremely small;
Moreover, there are problems in that it is difficult to obtain the desired shape due to the extremely high deformation resistance, and that the life of the mold is shortened because it is necessary to use a high temperature during molding. . Therefore, in the past, there were major restrictions on the shape and dimensions of the pipe.

[Purpose of the invention] The present invention solves the problems of the conventional technology, and enables complex-shaped pipes such as perforated pipes and finned pipes made of oil-releasing material, and these pipes to be manufactured without being restricted by shape or size. The purpose is to provide a method for manufacturing at low cost through simple steps.

[Summary of the Invention] As a result of extensive research in order to achieve the above object, the present inventors have developed a method for manufacturing complex-shaped pipes made of difficult-to-process materials, especially the outer wall members, using conventional processes such as forging and wire drawing. By applying the thermal spraying method and manufacturing it as a thermally sprayed layer instead of manufacturing it later, it is possible to manufacture it at a low cost without being limited by the shape and dimensions of the pipe as in the past. Moreover, the present invention was completed based on the discovery that the outer wall member of the pipe thus obtained has mechanical properties equivalent to those obtained by forging, wire drawing, etc.

That is, the difficult-to-process material pipe of the present invention includes an outer wall member made of a difficult-to-process material, and a projecting wall that has at least one end fixed to the inner circumferential surface of the outer wall member and projects into a space surrounded by the outer wall member. A pipe made of a difficult-to-process material, characterized in that the outer wall member is a thermally sprayed layer, and the manufacturing method includes: an outer wall member made of a difficult-to-process material; A method of manufacturing a difficult-to-process material pipe comprising a protruding wall member having one end fixed and protruding into a space surrounded by the outer wall member, wherein the projecting wall member is fixed to a support to produce a pipe made of a difficult-to-process material. The present invention is characterized in that it includes a step of forming a base body having an outer circumferential surface corresponding to the inner circumferential surface of the outer wall member, and forming the outer wall member on the outer circumferential surface of the base body by applying a thermal spraying method.

The difficult-to-process material pipe of the present invention is, as described above, composed of an outer wall member made of a difficult-to-process material and a protruding wall member, and specifically, for example, bamboo 1 [A(a) Examples include porous pipes and finned pipes, the cross section of which is shown in (b). That is, the first
Figure (a) shows a porous pipe that is fixed to an outer wall member 1 made of a difficult-to-process material and to the inner circumferential surface of this outer wall member 1, and divides the internal space of this outer wall member into a plurality of spaces (four in the figure). It is composed of a protruding wall member, that is, a partition wall 2. On the other hand, FIG. 1(b) shows a finned pipe, which, like the above, is composed of an outer wall member 1 and a protruding wall member, that is, fins 3. Note that the difficult-to-process materials include, but are not particularly limited to, W, Mo, Ta, Nb, and the like.

For these pipes made of a difficult-to-process material, it is sufficient that the outer wall member 1 is made of a thermally sprayed layer of a difficult-to-process material, and there are no particular restrictions on the material, dimensions, cross-sectional shape, etc. of the protruding wall member. In other words, the protruding wall members such as the partition wall 2 and the fins 3 may be made of the same material as the outer wall member or a different kind of difficult-to-process material. Structural fully flexible materials may also be used.

Next, a method for manufacturing the difficult-to-process material pipe of the present invention will be explained.

First, the first step of manufacturing the porous pipe shown in FIG. 1(a) will be explained with reference to FIGS. 2(a) and 2(b).

That is, first, as shown in FIG. 2(a), the ends 2a to 2d of the partition wall member 2 are connected and fixed by supports 4a to 4d, respectively, to form a base for forming an outer wall member. At this time, the outer circumferential surface of the base body corresponds to the inner circumferential surface of the outer wall member.The material constituting the supports 4a to 4d may be a low melting point metal such as Cu, A-type metal, or gypsum. It is possible to use inorganic compounds that can be ground into powder. In this case, the supports 4a to 4d are finished to a dimension obtained by removing the thickness of the partition wall from the circumferential length of the divided body obtained by dividing the cylinder into four parts, and the outer surface of the cylinder as a whole is is configured. Note that this support does not necessarily have to be a cylinder divided into four parts, and may be, for example, a cylinder divided into four parts.

Then, it is preferable to perform, for example, a blasting treatment on the outer surface of the base body consisting of the support and the partition wall, in order to improve the adhesion between the separation layer and the thermally sprayed layer in the next step.

Thereafter, as shown in FIG. 2(b), a thermal spraying method is applied to the outer surface of the base consisting of the above-mentioned partition wall member 2 and supports 4a to 4d to form an outer wall member l made of an oil-releasing material. Form. Although ordinary thermal spraying methods performed at normal pressure may be applied to this step, in particular, spraying methods performed in a low-pressure inert gas atmosphere may be used.
When the so-called low-pressure thermal spraying method is applied, difficult-to-process materials, especially W,
This is more preferable because it prevents Mo from oxidizing and allows a denser sprayed layer to be obtained. below,
This low-pressure thermal spraying process will be described below. That is, in this process, the powder of the difficult-to-process material mentioned above is used as the raw material powder,
It is carried out in an inert gas atmosphere at low pressure. The type of inert gas used at this time is not particularly limited, and examples thereof include helium (He), argon (Ar), and a mixed gas thereof. The pressure of this inert scum is preferably set to 10 to 760 Torr, more preferably 10 to 250 Torr, and the raw material powder preferably has a particle size of about 10 to 5011J.

In this way, the outer wall member l made of a thermally sprayed layer of difficult-to-process material
After forming the support body 4 to a predetermined thickness, if necessary,
A to 4d may be removed, and it is preferable that this removal step is appropriately selected from among pulverization removal, removal by a chemical method, removal by heating and melting, etc., depending on the material of the support.

The porous pipe shown in Figure 1(a) is completed as described in 1-1 below, but after this, the pipe is heated at a temperature of about 0.3 to 0.5 times the melting point (expressed in absolute temperature) of the pipe. It is preferable to perform heat treatment in order to alleviate the distortion of the sprayed layer and improve the adhesion between the sprayed layer and the partition wall.

In addition, if you use a finned pipe as shown in Figure 1(b),
In the case of IJ construction, (finally, it is the same as the manufacturing process of the porous pipe described in -h, but the first two steps, that is, the fixing and supporting process of the protruding wall member, that is, the fin 3, Since the supporting bodies 4a to 4d fixed to the outer periphery alone do not have sufficient support capacity for the fins, it is preferable to additionally use a core material 5, for example, in the shape of a solid cylinder as shown in the figure.
The tip of the fin 3 is embedded in this 5 at a predetermined position to securely support it. As this core material 5, for example, Cu, A5L
A low melting point material such as gypsum or an easily pulverized inorganic compound such as gypsum can be used, and the core material 5 may be removed after the thermal spraying process is completed.

[Examples of the Invention] Example 1 (Structure of Porous Pipe) A porous pipe having two passages as shown in FIG. 4 was manufactured. That is, the thickness is 5 cm, the width is 20 cm, and the length is 200 m.
m W plate 12, inner [18 mm, outer diameter 20 mm, length 2
00 m5 Cu halved pipes 14a and 14b (cutting allowance 5 mm) were combined and fixed, and the base and its outer surface were blasted with alumina powder having a particle size of 0.5 mm.

Next, using a low-pressure thermal spraying device using plasma arc heating, while rotating the base in an Ar atmosphere of approximately 150 Torr, W powder with a particle size of 10 to 50-50 mm was thermally sprayed to a thickness of 2 mm to form the W outer wall member 1. was formed. Thereafter, by immersing this in concentrated nitric acid, the Cu support 1
4a and 14b were dissolved and removed to complete a porous pipe.

When the obtained porous pipe was subjected to a He gas leak test between the two passages, it was found that 10 = Torr
++ l/sec or less, and it was confirmed that the airtightness was very good.

Example 2 (Production of porous pipe) A porous pipe having four passages as shown in FIG. 1 was produced. That is, in FIG. 2 (1), the thickness is 51,
A support body 2 obtained by welding Mo plates with a width of 20 mm and a length of 2005 m in a cross shape in the longitudinal direction, and an inner diameter of 18 mm and an outer diameter of 20 mm.
1■, length 200 single-layer 4-section Cu pipe 4a to 4d (
Each material had a cutting allowance of 5 am) and was assembled and fixed as shown in the figure, and its outer surface was blasted in the same manner as in Example 1 above.

Next, low-pressure thermal spraying was performed in the same manner as in Example 1, except that Mo powder with a particle size of 30 to 50 pl was used as the raw material powder, to form an outer wall member 1 with a thickness of 2 a+m.
Thereafter, heat treatment was performed at 1200'C in vacuum for 6 minutes to melt and remove the Cu support, completing a porous pipe.

When a He gas leak test was conducted between adjacent passages of the obtained porous pipe, it was found that the leakage of He gas was 10' Torr.
It showed good airtightness of r*l/see or less.

Example 3 (Manufacture of finned pipe) A finned pipe having eight fins as shown in FIG. 5 was manufactured. In other words, the thickness is 2mm, the width is 8m, the length is 2
The fin 13 made of a Mo plate with a diameter of ioam
Eight pieces were fixed to a core material 15 made of a solid cylindrical body made of Cu at a depth of 2 mm at intervals of a center angle of 45° in the circumferential direction. Then, as a support between each fin, the inner diameter 2211
An 8-piece Cu pipe 24a to 24h (cutting allowance 2 mm) was fixed, and its outer surface was blasted in the same manner as in Example 1.

Thereafter, low-pressure spraying of Mo was carried out in the same manner as in Example 2, except that the atmospheric gas was changed to Ar gas at 250 Torr, to form an MO outer wall member 1 with a thickness of 2 mm. Next, heat treatment was performed at 1200° C. for 5 minutes in an Ar atmosphere to melt and remove the Cu core material and support to complete a finned pipe.

The outer wall member of the finned pipe thus obtained by the low-pressure thermal spraying method was cut into a length of 5 mm in the axial direction, and this was used as a test piece for a tensile test. and.

The tensile breaking strength of this test piece at room temperature and 1000°C was measured. As a result, at room temperature 72,4
kg/ ■2.19.2 kg/m1 at 1000℃
It was found to have a breaking strength of 12. On the other hand, the breaking strength of an external wall member made of conventional hot forged material is 40% at room temperature.
~60 kg/mm2.10-20 k at 1000℃
g/a++*2, and from the above, it is clear that the finned pipe of the present invention has mechanical properties equivalent to or better than those made of hot forged material.

[Effects of the Invention] As is clear from the above description, the difficult-to-process material pipe of the present invention is a pipe having a complicated shape, such as a perforated pipe or a finned pipe, and the outer wall member thereof is made of a thermally sprayed layer. . It was confirmed that this outer wall member had comparable quality, ie, airtightness and mechanical strength, as compared to outer wall members obtained by conventional forging, wire drawing, etc. Furthermore, the difficult-to-process material pipe of the present invention can be manufactured by an extremely simple process called thermal spraying, and there are no restrictions on the cross-sectional shape or dimensions of the pipe. Its industrial value as a pipe etc. is extremely large.

[Brief explanation of drawings]

1(a), (b), 4 and 5 are cross-sectional views showing examples of the cross-sectional shape of the difficult-to-process material pipe of the present invention, and FIG.
a), (b) and FIG. 3 are cross-sectional views showing the manufacturing process of the difficult-to-process material pipe of the present invention. l...outside? Element. 2,12...Protruding wall member (partition wall), 3.13.
...Protruding wall member (fin), 4a to 4d, 14
a, 14b, 24a to 24h... Support body, 5.15... Core material. fal fbl Fig. 1 1al (bl Fig. 2 Fig. 3

Claims (4)

[Claims] (1) A difficult-to-process material pipe consisting of an outer wall member made of a difficult-to-process material, and a protruding wall member that has at least one end fixed to the inner circumferential surface of the outer wall member and projects into a space surrounded by the outer wall member. A pipe made of a difficult-to-process material, characterized in that the outer wall member is a thermally sprayed layer. (2) The difficult-to-process material pipe according to claim 1, wherein the difficult-to-process material is at least one of tungsten, molybdenum, tantalum, and niobium. (3) A difficult-to-process material pipe consisting of an outer wall member made of a difficult-to-process material, and a protruding wall member that has at least one end fixed to the inner peripheral surface of the outer wall member and projects into the space surrounded by the outer wall member. A method for producing a base, comprising: fixing the protruding wall member to a support to form a base having an outer circumferential surface corresponding to the inner circumferential surface of the outer wall member as a whole;
A method for manufacturing a pipe made of a difficult-to-process material, comprising the step of forming the outer wall member on the outer peripheral surface of the base body by applying a thermal spraying method. (4) The manufacturing method according to claim 3, wherein the thermal spraying method is a low-pressure thermal spraying method performed in an inert gas atmosphere.