FR2631861A1 - Process for the manufacture of an injection mould for a thermoplastic - Google Patents

Abstract

Process for the manufacture of a mould which consists in producing a mock-up of the article to be manufactured and then coating it with the material to be imitated. The latter is then covered with polystyrene. A counter-model produced from this combination is assembled with the model and, the polystyrene being removed, a flexible and elastic material is cast in its place. After demoulding, the counter-model is dressed with polystyrene and a chamotte is produced. The whole is subjected to firing and then ceramic is substituted for the polystyrene, the whole being again subjected to firing. An alloy is cast over the ceramic and will form the mould cavity, after demoulding. The process according to the invention is intended particularly for the motor industry.

Description

The present invention relates to a method for manufacturing an alloy injection mold for thermoplastic, foundry crude, usable in large, medium and small series, and capable of producing raw molding parts imitating any material having differences in important reliefs or fine details.

The realization of such a mold does not currently allow use in large and even medium series. Because of the great demoulding difficulties, consecutive to the existence of differences in relief to reproduce, the molds are produced by graining or sheathing, requiring the use of a chemical process, which does not give significant differences in relief in terms of character. uniform of its action.

The mold manufacturing process makes it possible to remedy this drawback and to obtain extremely satisfactory results.

FIG. 1 represents the first step of the process consisting in making a model of the part to be manufactured, precise and to the nearest volume (
Figure 2 shows the second step of the process. The model (1) shown in FIG. 1 is covered with the material or texture to be mapped i23.

FIG. 3 represents the third step of the process consisting in covering the material (2) to be reproduced with polystirene (3) 10 mm thick.

Figure 4 shows the fourth step in the process of making a wooden countermodel (4).

FIG. 5 represents the fifth step of the process consisting in manually removing the polystirene (3) and in casting by injection from its place, with a pouring nozzle (5) a flexible material, particularly sylastene (6).

Figure 6 shows the eighth step of the process.

The assembly is turned over and unmolded, the model (1) is removed. The counter model (4) is covered with 10 mm thick polystyrene (7). A chamotte (8) is then made.

FIG. 7 represents the seventh step consisting in submitting & steaming to 1100 the assembly resulting from the step represented in FIG. 6.

FIG. 8 represents the eighth step consisting in removing the polystirene (7) and pouring in its place ceramic (9), on the sylastene (6). The differences in relief of the sysiastene (6), reproduced during the realization of the fifth step, represented in FIG. 5, are thus perfectly reproduced on the ceramic (9).

The disassembly and demolding of the assembly is carried out without risk of fracture, consecutive to significant differences in relief, by the removal of the sylastene (6), flexible material, it being specified that the syslastene is a two-component silicone elastomer vulcanizing at room temperature under l action of a catalyst.

FIG. 9 represents the ninth step of the process consisting in subjecting to baking, by leveling up at 1100, the chamotte (B) and ceramic (9) assembly.

FIG. 10 represents the tenth step of the process consisting in preparing the casting of an alloy. An internal cooling system <10) is implemented as well as the mascot of the recesses.

FIG. 11 represents the eleventh step of the process consisting in casting on the ceramic (9) an alloy (11), in particular in cupro-berrylium, steel, bronze, which will be the imprint of the mold
The mold is removed from the imprint by destruction or dismantling. The footprint, after sanding, is rough foundry.

The manufacturing process of the mold is applicable to any field, and particularly to the automotive industry for the manufacture of fillings imitating a texture.

Claims (2)

ZETENDICATIONS 1) Method of manufacturing an injection mold for thermoplastic in that it makes it possible to imitate any material having differences in. important relief or fine details, characterized by the fact that it comprises the following stages - A first stage consisting in carrying out a model of the part to be manufactured, precise and to the nearest volume. - A second step in the process during which the model is covered with the material or texture to be imitated. - A third step consisting in covering the reproducing material with 10 mm thick polystyrene. - A fourth step consisting in making a wooden counter model. - A fifth step consisting in manually removing polystirene and pouring it by injection in its place, with a pouring nozzle, a flexible material, particularly sylastene. - A sixth step according to which the whole is turned over and unmolded; the model is removed and the counter model is dressed in 10 mm thick polystyrene. A chamotte is then made. - A seventh step consisting in subjecting to steaming at 1100 the assembly resulting from step 6. -An eighth step consisting in removing the polystyrene and pouring ceramic in its place, on the syl astene. - A ninth stage consisting in subjecting to steaming, by leveling up to 1100 *, 1 the whole chamotte and ceramic. - A tenth step consisting in preparing the casting of an alloy. An internal cooling system is implemented as well as the mascot of the recesses. - An eleventh step consisting in pouring on the ceramic an alloy, in particular in cupro-berrylium, steel, bronze, which will be the imprint of the mold. The mold is removed from the imprint by destruction or dismantling. 2) Method according to claim t characterized in that the mold produced is raw foundry and the parts leaving the mold raw molding.