DE1504304A1 - Process for the production of casting models for full mold casting and casting model produced according to the process - Google Patents

Description

Process for the production of casting models for full oral casting and casting model produced according to the process.

The invention relates to a method for producing casting models for full mold casting from foamed, granulated plastic, especially polystyrene and a casting model made using this process.

Cast models for full mold casting are made of gasifiable material and remain in the mold after molding. Only through the hot, flowing The cast model is destroyed and gasified when the melt is poured.

It is known to produce casting models for full mold casting without cutting, wherein foamable plastics such as polystyrene and the like. In a closed Schäwnform be introduced in such a metered manner that after the foaming process the cavity of the Shape is completely filled by the model, with the plastic grains through the internal foaming pressure is firmly pressed against each other and welded together will.

This procedure can only be carried out using a Schäwuforn which in turn is to be produced according to the original model. The model for pouring the foaming form, would be conceivable also parts of a die for the Pressing and deep drawing of sheet metal or. Matrices for pressing plastic or plastic Ceramic parts, is known to be made of a plaster or cast resin impression of the master model obtain. These plaster or resin casts are permanent models and can be Do not use in the full normative process.

In order to take advantage of the full mold casting process, especially with Manufacture of individual parts or small quantities offers, to be able to use, suggests the invention before, the imprint of the master model from one by the action of heat easily gasifiable material, for example using pre-expanded plastic granulate, in particular polystyrene granulate to produce.

According to the invention this is achieved in that the pre-expanded Plastic granulate with a hardening that melts easily under the action of heat - and / or gasifiable binder wetted or coated and in a warm state the original model to be cast is poured and that the surface of the resulting and after cooling, removable plastic foam models with the help of an Uborzuges Made of easily meltable and gasifiable materials, such as paraffin or the like. Smoothed will.

In order to treat the foamed plastic granules through the In order not to damage the heat of the binders to be applied, binders are used, which can be applied to the plastic at preferably 50 to 900C. That is, as attempts have shown, the easiest way to achieve by mixing paraffin, which are composed of hard or soft paraffins. By the mixing ratio the softening point and thus the processing temperature can be determined.

The granules to be used for the impression are preferred stored with a binder coating at room temperature. Only when used the appropriately prepared amount is heated to around 50 to 900 C and on the Original model applied. That so @@@@ tandene foam model can if necessary, the surfaces can be smoothed by making the indentations of the surface coated or covered with easily meltable and / or gasifiable substances such as paraffin fill out. Due to the measures taken, the weight of the applied Fillers and smoothing agents to a fraction, e.g. around 75; and more of the quantity reduced, which would be necessary if such a coating was carried out as has been customary up to now Splashing, dipping and the like as a cohesive film. Corresponding the smaller amount of material used, the gasification is faster and residue-free. In addition, the dimensional accuracy can be increased and the machining allowance be reduced.

With the help of this method, impressions of Master models that have curved surfaces, such as templates, pressing tools for the Body shop and the like.

To carry out the process for the production of casting models from foamed plastic granulate are advantageously solvent-free binding agents, in particular paraffin, thermoplastics and the like are used.

Further details of the invention are from the drawing and the following Description to be taken.

Figure 1 shows the model 1 of an insulator made of porcelain in the wet pressing process will be produced. According to the invention, the casting mold 2 is used for a press ram made by being foamed in loosely and with a heat effect easily meltable and / or gasifiable binders wetted or coated plastic granules 2a can be poured onto the model 1 to be cast while it is warm. To that To make it easier to fill up, afyd the model 1 preferably in a frame, box or an rdar 3 inserted.

The invention is particularly suitable for the production of models, such as stencils, press tools and the like. of master models with curved surfaces. It is not limited to the example given, rather the subject matter of the invention can also be used in combination with known objects.

Claims (2)

Patentpns claims 1) Process for the production of casting models for the full mold casting process with pre-wonding of pre-foamed, granulated plastic, in particular polystyrene, characterized in that the pre-expanded plastic granulate (2a) with cinom, easily meltable and / or gasified under the action of heat The binding agent is wetted or coated and in the warm state on the basic model to be molded (1) poured out and that the obor surface of the resulting and after cooling removable synthetic foam models with the help of a cover made of light melt - and gasifiable material, such as paraffin or the like. Is smoothed. 2) casting model according to the method of claim 1 or 2, characterized characterized in that the foamed plastic granules with preferably solvent-free Binders, especially paraffin, thermoplastics and the like. Are connected. L e r s e i t e