SE519139C2 - Method of forming holes or cavities in sintered and machined metal objects - Google Patents

Abstract

The method is used to produce holes in sinter metals in connection with plastic deformation such as swaging or forging or in combination with pressing and is of special advantage when long holes with, compared to the length, a small diameter or irregular cavities shall be produced. When making holes, one in the sinter metal inserted core of a brittle material like glass or porous ceramic material is used. The core is crushed during the plastic deformation or pressing. The core inserted can have any shape. The crushed core, usually as a powder, can after the plastic deformation easily be removed, poured out. The method has a special advantage in connection with sintering, as the brittle core can be introduced in connection to the consolidation of the powder and after that take part in the sintering process. At the plastic deformation or pressing to follow, the brittle core will be crushed.

Description

519 139 z steel bar or similar, perform the plastic machining and then drill out the relatively soft steel bar. However, the method becomes relatively complicated and expensive.

If heels with a complicated shape are to be produced, pressing and sintering of the construction part must usually take place with the construction divided into two or more parts, where the cavity is formed during the pressing. Thereafter, the sintered parts are joined together by welding, soldering or the like. This method also becomes complicated and expensive. In addition, the joining itself often involves problems.

DISCLOSURE OF THE INVENTION The invention intends to create a cavity in the sintered body by using a brittle core, for example of glass or porous ceramic, which is crushed by a suitable form of plastic processing or pressing. The crushed core can then be easily removed, thereby leaving the desired cavity in the sintered body.

The principle of the method (Fig. 1) consists in inserting into the cylindrical body of sinter metal (1) shown here in the powder pressing a core (Z) of brittle material of such a kind that it does not change appreciably during sintering. After the powder pressing, sintering of the powder body is performed according to the routine conventional for the material. During a subsequent plastic processing, the brittle core is crushed. Alternatively, a brittle, porous core may be used, which is crushed upon subsequent pressing. The crushed, powdered core can now be easily removed, usually poured out.

The principle of the method when a cavity of more complicated shape (Pig. 2) is to be achieved consists in inserting into the body of sintered metal (1) the brittle core with a not simple geometric shape (2).

After sintering and plastic processing or pressing, the crushed core can be removed, usually poured out.

DESCRIPTION OF FIGURES.

Pig. 1 shows a sintered body (1) into which a cylindrical body (2) of a brittle material is inserted.

Pig. 2 shows a sintered body (1) into which an irregular body (2) of a brittle material is inserted. 519 139 3 o n | a | ao PREFERRED EMBODIMENT.

The core of brittle material can be introduced in different ways. Normally, it is advantageous to introduce the core in connection with pressing the powder into a so-called green body. Alternatively, the core can be inserted into a heel drilled out of the pressed green body. Then sintering takes place.

The material in the core must be able to withstand the sintering temperature without major deformation and must not react with the sintered metal. Another alternative is to, after sintering, insert the core into a heel drilled from the sintered metal. Then plastic processing such as hammering or forging takes place. Alternatively, if a porous core is used, pressing, for example, isostat pressing can be used.

The material in the core can be glass or some form of ceramic. For materials with a moderate sintering temperature, ordinary soda glass can be used, while for higher sintering temperatures, quartz glass should be used. Ceramics include porcelain and alumina, which should preferably be porous to be more easily crushed during processing.

This is especially the case if a pressing operation is used to crush the core.

Attempts to apply the patent in the manufacture of armor-piercing projectiles have been made. In a rod of a tungsten-nickel-iron alloy, a rod of quartz glass was inserted in the center, which after plastic processing (hammering) was crushed and could be easily removed, poured out. Thereafter, a core was introduced into the projectile subject. (compare Swedish Patent No. 465,843).

Claims (4)

10 15 20 519 139 PATENT REQUIREMENTS Method for forming holes in sintered metal by inserting a core which, after sintering during subsequent plastic processing or pressing, is removed, characterized in that: the core is made of brittle material, which is crushed during plastic processing and may be of glass, ceramic or similar. Method according to claim 1, characterized in that the brittle core is introduced into the sintered metal in connection with pressing of the powder. Method according to claim 1, characterized in that the brittle core is introduced into the sintered metal in cavities in the pressed green body. Method according to claim 1, characterized in that the brittle core is introduced into cavities in the sintered metal after sintering.