JPH0154402B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the above-mentioned method for manufacturing a clad metal pipe by hot extruding a cylindrical billet having a concentric cross section and consisting of a plurality of material layers. This invention relates to a method of applying powder metallurgy to one layer of material.

[Conventional technology]

Conventionally, as a method for producing billets for hot extrusion of clad metal pipes by powder metallurgy, for example, as shown in Example 2 in Japanese Patent Application Laid-Open No. 56-9302, a billet of cylindrical shape is used. An intermediate wall is further placed inside a capsule that has inner and outer walls, and the outside and inside of this intermediate wall are filled with different types of powder. After removing the intermediate wall and deaerating the inside of the capsule, the capsule is sealed and left in a cold isostatic state. It is known to compress using hydraulic pressure and then hot extrusion.

[Problem that the invention seeks to solve]

According to the above-mentioned conventional methods, the positioning of the intermediate wall must be performed accurately, and the internal and external powders may move and mix during removal of the intermediate wall or subsequent handling of the capsule, or uneven distribution. I become familiar with it.
This is a problem in that it has a negative effect on the quality of the clad pipe. Another problem is that it is difficult to raise the temperature during induction heating performed prior to hot extrusion because the entire material is powder. Further, after hot extrusion, processing to remove the capsule material must be performed on both the inner and outer surfaces, and the capsule has a dual structure inside and outside, which increases the cost of the capsule.

Furthermore, in order to obtain a billet with good shape and dimensions when applying isostatic cold hydrostatic pressure to increase the packing density of the powder in the capsule filled with powder, Japanese Patent Publication No. 57-17042 discloses As if
The conventional technology also had the problem of having to use a capsule having a special shape near both ends.

[Means for solving problems]

The means according to the first invention includes a container made of rubber or a rubber-like substance, which is made of a coaxial cylindrical double inner and outer circumferential wall and a bottom wall that closes between the double circumferential walls at one end of the double circumferential wall, After accommodating a malleable metal cylindrical material along one of the circumferential walls of the double circumferential wall and a thin metal cylinder along the other circumferential wall in the container, the cylindrical material and the thin metal cylinder are The thin metal cylindrical body and the powder material are integrated with the cylindrical material by filling the container with a powder material between them, sealing the container with a lid made of rubber or a rubber-like substance, and applying isostatic hydrostatic pressure from the outside. compressed and consolidated,
In this method, metal plates are welded to both end faces of the integrated cylindrical body to form a billet, and this billet is hot extruded.

The means according to the second invention differs from the first invention in that in the first invention, the malleable metal cylindrical material is arranged along one of the peripheral walls of the container, but that one peripheral wall is omitted, Everything else is the same.

[Effect]

In the first and second inventions, the malleable metal cylindrical material is one layer of the clad pipe and is originally quite thick in the material stage before extrusion. When the powder material is compressed and consolidated by applying isostatic hydrostatic pressure, deformation occurs on the side of the thin cylinder and the powder material. Therefore, as a result, a thin metal cylinder is covered with a solidified layer of powder material with a uniform thickness on the inner or outer periphery of the malleable metal cylinder. Become.
The purpose of applying this isostatic pressure is to increase the density of the powder material layer and increase its thermal conductivity, thereby increasing the rate of temperature rise during heating and reducing the variation in temperature rise. . As a result of applying isostatic hydrostatic pressure, the outer diameter or inner diameter of the billet becomes
Since this is equal to the outer diameter or inner diameter of the malleable metal cylinder, the outer or inner diameter of the resulting billet will be the desired size by controlling the dimensions of the malleable metal cylinder. Moreover, if you understand the relationship between the pressing force and volume change of the powder material, you can accurately determine what the inner diameter or outer diameter of the side where the thin-walled cylinder is present will be after applying a predetermined isostatic hydrostatic pressure. can be predicted. Therefore, the billet has accurate inner and outer diameter dimensions, and the layer of malleable metal and the layer of compressed powder material necessarily meet at a clear boundary, and the position of the boundary is also precise. It is accurate. Note that the appropriate isostatic hydrostatic pressure to be applied is 2 to 8 t/cm ² , which increases the packing density of the powder to 80 to 90%.

Further, even if the powder material alone does not necessarily have good self-shape retention when compressed, it can be used. This is because the powder material is held between the malleable metal cylinder and the thin metal cylinder, and as a powder material, it is necessary to hold the powder material in such a way that it does not fall off by the time metal plates are welded to both end faces. It would be good if it had self-retention property.

For hot extrusion, the billet is heated,
The temperature of the layer of malleable metal rises quickly, and the compacted powder layer has increased density, which increases its thermal conductivity, so the temperature rises quickly due to heat conduction from the layer of malleable metal. Since it is heated, the entire body is efficiently heated to a predetermined temperature.

The heated billet is loaded into a hot extruder,
Extruded. The metal plates at both ends have the effect of preventing oxidation of the powder material at both ends. Also, during extrusion, the metal plate on the tip side acts to suppress the outflow of the powder material until a sufficiently high pressure is reached, thereby applying an upsetting force to the powder part, making it a high-density state, and then extruding it. Make it. The metal plate on the rear end side becomes a disk card (rear end truncation part), which improves the yield of the main body. The resulting tube has a clad structure consisting of a layer in which the malleable metal cylinder constituting the billet is processed and a solid layer converted from a powder layer. Note that the thin metal cylinder material used to create the billet forms a thin film that adheres to the surface of the solid layer converted from powder, so if this film is harmful, it should be removed by mechanical or chemical means. Remove this.

〔Example〕

A first embodiment is shown in FIGS. 1 and 4. In FIG. 1, 1 is an outer circumferential wall, 2 is an inner circumferential wall, 3a is a bottom wall, and 3b is a lid, all of which are made of rubber. By assembling the outer circumferential wall 1 and the inner circumferential wall 2 to the bottom wall 3a, a container 9 is formed coaxially. When the malleable metal cylindrical material 4 and the thin metal cylinder 6 are housed in the container 9, the powder material 5 is then filled, and the lid 3b is fitted, the state shown in FIG. 1 is obtained. The contents of the container are compressed using a cold isostatic press, and metal plates 7 are welded to both ends of the cylindrical body taken out from the container 9 to obtain the billet 10 shown in FIG. This billet 1
0 is hot extruded to obtain a clad pipe.

A second embodiment is shown in FIGS. 2 and 5. In the figure, parts that are the same as those in FIG. 1 are designated by the same reference numerals. The difference from the first embodiment is that a malleable metal cylindrical material 4a is accommodated along the inner circumferential wall 2 of the container 9, and the outer circumferential wall 1
This is the point where the thin metal cylinder 6a is accommodated along the line.
Next, the powder material 5a is filled and the lid 3b is fitted, resulting in the container enclosure shown in FIG. This is compressed by cold isostatic press in the same manner as in the first embodiment, taken out from the container 9, and metal plates 7a are welded to both ends to obtain the billet 10a shown in FIG.
This billet 10a is hot extruded to obtain a clad pipe.

A third embodiment is shown in FIGS. 3 and 4. This embodiment differs from the first embodiment in that the rubber outer circumferential wall 1 of the container 9 is omitted, and the cylindrical material 4 acts as the outer circumferential wall. That is, the inner circumferential wall 2 and the cylindrical material 4 themselves are arranged coaxially due to the relationship between the bottom wall 3c and the lid 3d, and the inside is shielded from the outside. In this case, the bottom wall 3c, the lid 3
Since d fits into the cylindrical material 4 at the outer peripheral edge, it is different from that in the first and second embodiments, but in any case, the sealing effect is good. A container 9a formed of an inner peripheral wall 2, a bottom wall 3c, and a cylindrical material 4
A thin metal cylinder 6 and a powder material 5 are housed inside the lid 3.
The one shown in FIG. 3 is the one with d fitted. This is compressed by a cold isostatic press similar to that in the first embodiment, taken out of the container, and welded to both ends of the metal plate 7, yielding the same billet 10 as in the first embodiment shown in FIG. It will be done. This billet 10 is hot extruded to obtain a clad pipe.

In the third embodiment, the case where the outer circumferential wall of the rubber container was omitted was shown, but when the cylindrical material is located inside and the outside is filled with powder material as in the second embodiment, the rubber The inner peripheral wall of the container can be omitted.

In each of the above embodiments, a simple annular metal plate 7 or 7a is welded, but a billet equipped with a hole for vacuum degassing is used, and the billet is evacuated before the hole is welded. may be closed and hot extruded.

〔Effect of the invention〕

As described above, in this invention, a clad metal tube including a layer obtained by powder metallurgy is manufactured by hot extrusion. Using a metal cylinder,
This is used for one peripheral wall of a holding part (capsule) for holding a powder layer. Therefore, according to the present invention, since the powder material and the thin-walled cylinder are deformed based on the malleable metal cylinder that does not deform when isostatic hydrostatic pressure is applied, first, the inner and outer diameter dimensions are accurate and it is possible to A billet for a clad pipe with clear and accurate boundaries is obtained, and since this billet is extruded, a high quality clad pipe with a constant cladding all around the circumference can be obtained.

Moreover, in billet forming, one of the two raw materials that make up the cladding does not deform, so there is no risk of them mixing or being unevenly distributed, and the thin-walled metal cylinder for holding the powdered raw material is a simple one. It is used only on either the inner or outer circumference of a cylinder, and when removing unnecessary coating from a manufactured cladding pipe, it is only removed from either the inner or outer circumference, which makes the work easier. It is simpler than before and the manufacturing cost is significantly reduced.

In addition, the metal plates at both ends of the billet are not only used to prevent the powder material from falling off and oxidize, but also to keep the powder part in a high-density state at the beginning of extrusion, which reduces the quality of the extruded tip of the clad pipe. Since the discard is formed at the end of extrusion, the quality of the extruded rear end of the clad tube does not deteriorate, and therefore the yield of the clad tube body is extremely high.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of the billet material and container before cold isostatic pressing according to the first embodiment of the present invention, and FIG.
The figure is a vertical cross-sectional view of the billet material and container before cold isostatic pressing in the second embodiment, FIG. 3 is a vertical cross-sectional view of the billet material and the container before cold isostatic pressing in the third embodiment, and FIG. The figures are longitudinal cross-sectional views of billets obtained in the first and third embodiments, and FIG. 5 is a longitudinal cross-sectional view of billets obtained in the second embodiment. 1...Outer peripheral wall, 2...Inner peripheral wall, 3a, 3c...
Bottom wall, 3b, 3d... Lid, 4, 4a... Malleable metal cylindrical material, 5, 5a... Powder material, 6, 6a
...Thin metal cylinder, 7,7a...Metal plate, 9,9
a... Container, 10, 10a... Billet.

Claims (1)

[Scope of Claims] 1. A container made of rubber or a rubber-like substance, which is made of a coaxial cylindrical double inner and outer circumferential walls and a bottom wall that closes between the double circumferential walls at one end of the double circumferential walls. After accommodating a malleable metal cylindrical material along one of the circumferential walls of the double circumferential wall and a thin metal cylinder along the other circumferential wall in the container, the cylindrical material and the thin metal cylinder are combined. Fill the space with powder material,
By sealing the container with a lid made of rubber or a rubber-like substance and applying isostatic hydrostatic pressure from the outside, the thin-walled metal cylinder and the powder material are compressed and solidified integrally with the cylindrical material. A method of manufacturing a hot extruded clad pipe using a powder metallurgy method, in which metal plates are welded to both end faces of a cylindrical body to form a billet, and the billet is hot extruded. 2. A hot extruded clad pipe made by powder metallurgy, in which one or both of the metal plates welded to both end faces of the cylindrical body are provided with holes for vacuum degassing, in the manufacturing method according to claim 1. manufacturing method. 3 A container consisting of a coaxial cylindrical double inner and outer peripheral wall and a bottom wall that closes between the double peripheral walls at one end of the double peripheral wall, one of the double peripheral walls is made of a malleable metal cylindrical material. the other peripheral wall and bottom wall are formed of rubber or a rubber-like substance, and a thin-walled metal cylinder is accommodated in the container along the peripheral wall formed of the rubber or rubber-like substance, and then the thin-walled metal cylinder and the above-mentioned cylinder are The thin metal cylinder and the powder material are separated from the cylindrical material by filling the space between the thin metal cylinder and the powder material, sealing the container with a lid made of rubber or a rubber-like substance, and applying isostatic hydrostatic pressure from the outside. A method for producing a hot extruded clad pipe using a powder metallurgy method, in which the billet is integrally compressed and consolidated, metal plates are welded to both end faces of the unified cylinder, and the billet is hot extruded. 4. A hot extruded clad pipe made by powder metallurgy, in which one or both of the metal plates welded to both end faces of the cylindrical body are provided with holes for vacuum degassing, in the manufacturing method according to claim 3. manufacturing method.