JPH0154401B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing a billet filled with powder material used for producing a tube by hot extrusion pressing.

<Conventional technology> The conventional method for manufacturing this type of billet is as follows:
It is well known to place a powder in a rubber container and form it into a tube under cold isostatic pressure, which is then placed in a tubular capsule to form a billet. However, in billets made by this method, it is difficult for the molded powder material to adhere tightly to the inner surface of the capsule, so there is a problem that induction heating is not uniformly performed before processing by hot extrusion press. Furthermore, depending on the type of powder, there is also the problem that the molded body collapses when taken out from the rubber container after cold isostatic pressing. As a method for solving these problems, Japanese Patent Publication No. 17042/1983 discloses a method in which a specially shaped capsule made of a thin metal plate is filled with powder and cold isostatically pressed.

<Problems to be Solved by the Invention> A problem with the conventional method using a metal capsule is that when metal plates for encapsulation are encapsulated at both ends of a metal cylinder by welding or other means, the end metal plates do not move in the radial direction of the cylinder. Even if the metal cylinder is compressed by applying isostatic pressure using a cold isostatic press to restrain deformation, the stress distribution during deformation becomes uneven, causing wrinkles in the metal cylinder.

In addition, if the capsule is evacuated before sealing, the increase in the internal pressure of the capsule during hydrostatic pressing will be small, so the frequency of wrinkles will be reduced, but the addition of an evacuation process using an evacuation device will also increase equipment costs. The disadvantage is that the manufacturing cost of the powder-filled billet is high. Furthermore, in addition to the above-mentioned problems, in the method of using a specially shaped capsule, it is necessary to design the capsule by predicting the change in the shape of the capsule during cold isostatic pressure, especially the deformation of the processed portion of the capsule.

Separately, this type of billet may have a dummy connected only to the tip or both the tip and rear end during extrusion processing to improve extrusion workability and yield. For the dummy, a short cylindrical metal piece will be welded to the billet end with the end slightly extended in the axial direction. However, in this welding, there is a problem in that while it is easy to weld the outer peripheral portion of the dummy and the billet with their respective end surfaces butted against each other, it is difficult to weld the inner portion.

<Means for solving the problem> The means according to the invention provides a seal made of rubber or rubber-like material, consisting of a coaxial cylindrical inner circumferential wall and a cylindrical outer circumferential wall, and a bottom wall and a lid between the inner and outer circumferential walls. A container is used, and inner and outer metal cylinders, at least one of which is thin, are arranged along the inner circumferential wall and the outer circumferential wall, respectively, and the inner metal cylinder is formed longer than the outer metal cylinder, so that both metal cylinders are formed. The cylinders are positioned so that they coincide at one end or so that the inner metal cylinder protrudes from the outer metal cylinder at both ends, and the billet powder material is placed between the two metal cylinders as it is or the billet powder material is compressed into a cylindrical shape. The preformed material is loaded and the container is sealed without being evacuated, and the sealed container is pressurized by a cold isostatic press to form a tubular body integrating the metal cylinder and powder material. When the body is removed from the container, the exposed end surface of the powder material of the tubular body is connected to the protruding end surface of the inner metal cylinder with an inner hole that fits around the outer circumference of the inner metal cylinder and an outer diameter of the outer metal cylinder. This method is characterized in that the matching end faces of both metal cylinders are welded so as to be sealed with an annular disk so as to be sealed with a short cylindrical dummy having the same outer diameter as the metal cylinder.

<Function> According to the above method, a thin metal cylinder is placed along at least one of the inner peripheral wall and the outer peripheral wall in a container made of rubber or a rubber-like material, and the billet powder material is preformed as it is or into a cylindrical shape. The container is sealed, and the sealed container is pressurized by cold isostatic press, so that the entire container is reduced approximately uniformly. That is, a tubular body is obtained in which the tubular space inside the container in a non-pressurized state is isotropically reduced. At the stage of the tubular body, the thin-walled metal cylinders on the inner and outer surfaces adhere to and enclose the powder portion, and the powder portion does not collapse.

In this method, evacuation is not performed prior to sealing the container, but since there is no metal plate on at least one of the ends and there is no restraint during contraction, the occurrence of vertical wrinkles seen when using a metal capsule is avoided. I can't see it at all.

Welding of the dummy or annular disk is performed to the outer metal cylinder end and the inner metal cylinder end.

<Example> Fig. 1 shows the state of the first example of the present invention before cold isostatic pressing, in which 1 is an inner peripheral wall made of relatively thin rubber, and 2 is an inner wall made of relatively thin rubber. This outer peripheral wall is made lower than the outer peripheral wall 1. Both are adhered to a rubber bottom wall 3 with glue to form a rubber container 11. Inserted into the rubber container 11 are an inner metal cylinder (hereinafter referred to as the inner cylinder) 4 made of thin-walled metal and an outer metal cylinder (hereinafter referred to as the outer cylinder) 5 also made of thin-walled metal. . In order to connect a dummy 14 to be described later, the inner cylinder 4 is formed longer than the outer cylinder 5, and its lower end coincides with the lower end of the outer cylinder 5, and its upper end extends above the upper end of the outer cylinder 5 by the length of the dummy 14. It is located prominently. The bottoms of the inner tube 4 and the outer tube 5 are closed with a thin metal annular disk 6, but this annular disk 6 may be omitted in some cases. A powder material 7 is filled between the inner cylinder 4 and the outer cylinder 5. The upper ends of the inner tube 4 and the outer tube 5 are closed with a rubber lid 8. As shown in the figure, the lid 8 includes an end plate 9, an outer circumferential wall portion 10 extending downward in a right angle direction from the outer circumferential edge of the end plate 9, and having a tip fitted onto the outer circumferential surface of the outer circumferential wall 2, and the end plate 9. An inner peripheral wall portion 1 extending upward along the inner cylinder 4 from the inner peripheral edge of the
It consists of 2. The inner circumferential wall portion 12 extends above the inner cylinder 4, and is provided with a housing portion 12a for accommodating the protruding portion of the inner cylinder 4 between the inner peripheral wall portion 12 and the outer circumferential surface of the inner peripheral wall 1. Then, by folding the upper end 13 of the inner peripheral wall 1 outward and covering the upper end of the inner peripheral wall 12, the space between the inner peripheral wall 1 and the inner peripheral wall 12 is sealed. This sealing operation is performed without evacuating the container. For example, chloroprene rubber is used as the material for the inner circumferential wall 1, outer circumferential wall 2, bottom 3, and lid 8, and as the powder material 7, gas atomized powder of 100 mesh or less is used.

As shown in FIG. 1, a sealed container filled with powder material is pressurized to a predetermined pressure using a cold isostatic press. When the pressure is reduced, gas is discharged from the powder material 7 filled during pressure molding, but this gas flows out between the rubber container and the inner cylinder 4 or outer cylinder 5, and is caused by the expansion and deformation of the container. It is held there. The internal tubular molded body produced by the pressurization is taken out from the rubber container, and a short cylindrical metal dummy 14 is placed at the upper end at the positions shown at 15 and 16 in FIG.
That is, the upper ends of the inner cylinder 4 and outer cylinder 5 are welded to obtain a billet 17 as shown in the figure. The reason why the inner cylinder 4 is made higher than the outer cylinder 5 is to facilitate this welding work. This billet 17 is hot extruded to produce a tube.

FIG. 3 shows a second embodiment of the present invention, in which a lid 81 and a bottom 82 having exactly the same structure as the lid 8 in the embodiment of FIG. 1 are provided at both ends of a container 21. Both ends of the inner cylinder 22 protrude further outward than both ends of the outer cylinder 23. In the figure, 25 is an inner peripheral wall, 2
6 is an outer peripheral wall. A dummy similar to the dummy 14 in FIG. 2 is welded to both ends of the obtained tubular molded body.

<Effects of the Invention> As described above, the method of the present invention does not perform evacuation prior to sealing the container, but since at least one of the ends does not have a metal plate and is not restrained during contraction, it is difficult to use when using a metal capsule. The vertical wrinkles that were observed are not observed at all. In addition, as mentioned above, during the compression molding of thin metal cylinders and powder materials, high rigidity that would inhibit deformation of both ends is not used, so the whole is reduced almost uniformly and maintains a tubular shape. It is not necessary to create a capsule with a special shape in which deformation near both ends of the capsule during cold isostatic pressing is predicted, unlike in conventional methods using capsules with a special shape. Therefore, according to the present invention, a homogeneous powder-filled tubular billet can be manufactured easily and at low cost. In addition, since the inner cylinder is made longer so that the inner hole of the dummy fits into the outer circumference of the inner cylinder, welding the dummy becomes very easy, improving work efficiency and ensuring reliable connection of the dummy. Therefore, the dummy works reliably to improve workability and yield during tube manufacturing.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a container filled with billet material powder for explaining the first embodiment of the present invention, and FIG. 2 is a diagram of a billet obtained by the method of the first embodiment. FIG. 3 is a longitudinal sectional view of a container filled with billet material powder for explaining a second embodiment of the present invention. 1, 25... Inner peripheral wall, 2, 26... Outer peripheral wall,
3,82...bottom, 8,81...lid, 4,22...
Thin metal inner cylinder, 5, 23...Thin metal outer cylinder, 1
1, 21... Container, 17... Billet.

Claims (1)

[Scope of Claims] 1. A hermetic container made of rubber or rubber-like material is used, which is composed of a coaxial cylindrical inner circumferential wall, a cylindrical outer circumferential wall, a bottom wall and a lid between the inner and outer circumferential walls; Inner and outer metal cylinders, at least one of which is thin, are respectively arranged along the inner peripheral wall and the outer peripheral wall, and the inner metal cylinder is formed longer than the outer metal cylinder so that both metal cylinders coincide at one end. Alternatively, the inner metal cylinder is positioned so that it protrudes from the outer metal cylinder at both ends, and the billet powder material is loaded as it is or the billet powder material preformed into a cylindrical shape by compression is loaded between both metal cylinders. The container is then sealed without evacuating the container, and the sealed container is pressurized using a cold isostatic press to form a tubular body that integrates the metal cylinder and powder material, and the tubular body is taken out from the container and The exposed end surface of the powder material of the tubular body is connected to the protruding end surface of the inner metal cylinder by a short cylinder having an inner hole that fits around the outer periphery of the inner metal cylinder and an outer diameter that is the same as the outer diameter of the outer metal cylinder. 1. A method for manufacturing a powder material-filled tubular billet, characterized in that the matching end faces of both metal cylinders are welded so as to be sealed with an annular disk so as to be sealed with a shaped dummy. 2 The hermetically sealed container has the inner peripheral wall and the outer peripheral wall made of relatively thin rubber or rubber-like material, the inner peripheral wall being longer in the axial direction than the outer peripheral wall, and at least one of the bottom and the lid having an end plate and an end plate. , an outer circumferential wall portion made of relatively thin rubber or rubber-like material provided on the outer circumferential edge of the end plate and fitted onto the outer circumferential surface of the outer circumferential wall; and an inner circumferential wall that is connected to the inner circumferential wall in a sealed state, and a portion of the inner metal cylinder that protrudes from the end of the outer metal cylinder is accommodated between the inner circumferential wall and the inner circumferential wall. 2. The method of manufacturing a powder material-filled tubular billet according to claim 1, further comprising a housing section for storing powder material.