DD271861A1 - METHOD FOR PRODUCING TOOLS - Google Patents

Abstract

The invention relates to a method for the production of tools that are elastically mounted as active working elements and by rotating movements excess material, the workpieces as ridge, molding material o. Ae. attached, remove. In order to be able to produce such tools much faster and cheaper, the method according to the invention consists in casting the tools in casting molds produced by the compacting method and cooling the melt with a speed leading to white or mottled solidification.

Description

Application blot of the invention

The invention relates to a method for the production of tools, which are elastically mounted as active working elements and for removing excess material which adheres to workpieces as a ridge, molding material o. Ä., Is used.

Characteristic of the known state of the art In the case of sparing deburring methods, tools with a geometrically determined cutting edge, such as milling cutters, turning and cutting tools, are used Planer chisels, files and needle cutters as well as tools with a geometrically indefinite cutting edge, for example Grinding wheel, used. These tools need a high wear resistance and at the same time a sufficient Possess break resistance. Therefore, tools with a geometrically defined cutting edge become predominantly High speed steels produced. These are high-alloyed steels with special carbide-forming elements, the structure of which after the Heat treatment of fine needled, tempered martensite as a matrix and incorporated therein primary and Secondary carbides of these elements consists. Due to the alloying elements and the relatively expensive Manufacturing methods, these tools are expensive. So it is already known, for example, cutters from the o.g. materials

to produce by investment casting, the required models and shapes require high accuracy and are therefore expensive to manufacture. In order for sufficient breakage e. To obtain order ductility, must be to the

Casting in any case connect a special cooling and / or heat treatment. Besides that is for realization

the required cutting geometry and cutting performance a final mechanical processing, usually a

Grinding the tools required. To reduce the material and manufacturing costs has been a method for producing a rotating tool

developed for cutting, in which on a tough core of hard, wear-resistant material existing working edges are welded (CH-PS 535938).

The same goal is aimed at using carbide-tipped tools. Despite the reduced effort, these tools are still relatively expensive. The He ¹ position of the tools used in deburring by grinding causes relatively high costs, since

To ensure the required due to the high rotational speed Briicnsicherheit the abrasive, the hard, the removal ensuring grains are incorporated into a special dimensionally stable material.

In SU-US 1191179 elastically mounted cutting elements are in a device for removing burr

used. These have, similar to broaches, obliquely to the cutting direction running cutting. Their preparation is thus consuming for the reasons already mentioned.

It has also been proposed a device for removing excess material in which as active Tool elements elastically mounted rotationally symmetrical body are used. In both technical solutions

the tool elements the contour of the to be described, the workpiece is pacsen, ie they balance independently gußbedingte irregularities, so that it be the entire gratbehaftete contour ^n; Beitan and even the smallest amounts ridge remove without causing the casting or the mold is damaged.

The peculiarity of this Entgratevorganges over the previously described, according to the laws of Spanungstechnik deburring process is that the excess material is removed from the casting,

without violating the casting contour with the tool. Only the surfaces that have ridge are processed

d. H. the thickness of the cross section to be separated is equal to the burr thickness. Thus, the disadvantage of the prior art is that the expensive tools of the tensioning technique are used for the deburring of castings.

Object of the invention

The aim of the invention is a method with which elastically mounted tools for removing excess material can be produced without much on-vand and cheap.

Darleguno 4es essence of the invention

With the elastically mounted tools used in the last-mentioned device for removing excess material, extensive investigations were carried out and new insights into the peculiarities of the deburring process compared to the known stressing process with tools with geometrically defined or

won undetermined edge. According to this, in contrast to most of the machining methods, the deburring of castings involves relatively brittle materials and, due to the small dimensions, in particular the thin cross-sections of the burr, a kind of breaking operation, with larger burrs, then smaller burrs, upon engagement of the tool When the tools approach the ridge base profile, the ridge pines erupt and finally the tools predominantly rub the contour. This last stage is comparable to a smoothing process, whereby the tools abut against the workpiece contour under pressure of the elastic elements. It is therefore not to be expected in any phase of the deburring process with a pure cutting process. The deburring process requires significantly lower forces than a conventional cutting process.

Based on these findings, the object of the invention is a method for producing tools

To develop for deburring, which takes into account the actual stress conditions of such a tool, it is straightforward and requires as few steps as possible.

According to the invention the object is achieved in that the tool in a manufactured according to the Vichtichtungsverfahren Casting mold cast from a cast iron material and the melt with a leading to white or mellierte solidification Speed is cooled. To achieve a particularly high hardness is in thicker tools at least in the deburring process in engagement

areas to realize a high cooling rate.

The particular advantage of the invention is that the new deburring tools made of cheap cast iron, which in the Foundries are usually readily available, namely GGL, GH, GGG, GT Rohguß, virtually in a single Process step can be produced, since it is at the deburring tools very simple and thus of the Foundries themselves are easily manufacturable geometric bodies. In addition, neither a subsequent heat treatment nor a final mechanical processing is required. Likewise, no special effort is required for the production of the molds. The accuracy that after the Ensuring compacting processes for finished shapes is sufficient. The tools according to the invention are also suitable for eliminating the burr of workpieces made of ductile materials. This burr is stretched or bent in a first phase, d. H. deformed beyond its yield point, and in the

second phase as described aborted.

embodiment Below, the invention will be explained in more detail with reference to an exemplary embodiment.

For the production of a disc-shaped tool for deburring a mold is made in Handformvorfahren. As molding sand, molding material of the following composition is selected:

91% quartz sand and 9% bentonite. The model sand is backfilled with a molding mixture consisting of 98% used sand, 1.5% virgin sand and 0.5% bentonite. The mold cavity is cut directly or tangentially. The assembled mold is then poured off with a melt for a GGL-25 casting material. Due to the very flat design of the disk-shaped !! Casting with a ratio of length to diameter smaller than 0.1, a high cooling rate and thus a white or mellierte solidification of cast iron melt is possible. This results in high hardnesses of over 50HRC in the edge zones of the GußKils, which form the working zones of the tool. In this way, a deburring tool is produced that meets the stress of dejuring with elastically supported tools. It is characterized by simplicity at extremely low cost and ensures low wear and thus long tool life. To intensify the molding process, the model can also be produced on an automatic molding line by a compression molding process.

Claims (2)

1. A process for the production of tools that are elastically supported as active working elements and by rotating movements excess material that adheres to workpieces as a ridge, molding material o. Ä., Remove, characterized in that the tool in a finished by the compression molding process mold cast from a cast iron material and the melt is cooled with a leading to white or mottled solidification speed. 2. The method according to claim 1 and 2, characterized in that only the outer regions of the workpieces are subjected to a high cooling rate.