DE601551C - Process for the production of molded parts with a very hard and dense surface - Google Patents

Description

Method of manufacturing before 'fittings with very hard and dense Surface When it comes to fittings with a very hard and dense surface, how they z. B. for gauges, jewels, gramophone needles and similar items are used to manufacture from tungsten or an alloy with a high tungsten content, this is how the known ones produced on the basis of tungsten carbide turn out to be Hard metals or hard metal alloys because of their brittleness and their porous properties Surface as unsuitable. The properties mentioned have the consequence: that the pore edges on the surface tear easily in use; whereby the Items made from the hard alloy will soon become unusable.

Iri such cases .well in which there is less on high mechanical Strength rather than great hardness, surface density and exact dimensional accuracy of the items to be manufactured arrives, the procedure described below offers a way in which very excellent results can be obtained. This method is according to the invention that in the manufacture of the molded pieces from sintered and% superficially carburized tungsten or an alloy with a high tungsten content the raw material after sintering through extensive mechanical pretreatment, like hammering or pulling, made surface-proof in a manner known per se, on it brought into the final shape and finally carburized.

For cast alloys, it has already been proposed- to process the cast, rather brittle body by rolling, hammering and the like, in order to convert its crystalline structure into a sinewy structure. Through this the ductility of the cast body is to be increased.

In contrast, it is with the method according to the invention about the treatment of bodies made of sintered alloys which crystallize does not occur.

The treatment according to the invention also only needs to The superficial layer of the body is acted to empty, and indeed is thereby no increase in elasticity, but an increase in hardness. That The method according to the invention is also primarily aimed at such items Carbide suitable for which there is less on ductility than on large, hardness and The absence of pores on the surface is important. Such items are e.g. B. gauges, jewels, Plug gauges, pins for measuring instruments and clocks, recording pins for records and similar items. In cases where particularly high mechanical strength is not required, cutting tools can also be used to the specified process manufactured Nverden, z. B. for the purpose of processing Records made of wax or molded articles made of hard rubber and the like.

When using the method according to the invention, for example following way. to be hit. From metal powders, e.g. B. tungsten powder and Cobalt powder is produced by pressing a body that approximates the final corresponds to the desired shape. This shaped body is sintered, which gives it he a firmness ;; which makes it possible to edit it by hammering, pulling or the like and thus to make it surface-tight. Thereupon the body gets through a low superficial post-processing brought into its final form and then carburized.

The method according to the invention offers the additional advantage that the shaping can be done more easily than z. B. when using cobalt-containing tungsten carbide alloys. In addition, the effect is shown that the material is down to small fractions of a Remains dimensionally accurate to a millimeter, even if - the carburizing continues for so long -will; until the carbon is about o; 5 mm called has penetrated into the surface. The carburizing can be done in any way, e.g. B. by embedding in coal or when Heating in Iz, carbon-releasing substances, can be brought about.

For certain purposes, the tungsten can also be wholly or partly through Molybdenum can be replaced, which yields alloys of somewhat greater toughness.

Claims (1)

PATENT CLAIM: Process for the production of fittings with very hard and dense surface, e.g. B. for measuring gauges or bearing stones, made of sintered and superficially carburized tungsten or an alloy with a high tungsten content, characterized in that the starting material after sintering through extensive mechanical pre-treatment,. -like hammering or pulling, in a manner known per se made surface-proof and then the pre-formed body into the final Shaped and finally carburized.