DE1508655C3 - Inorganic coating for a gasifiable casting model and its application - Google Patents

Description

3 4

resulting joints, gaps or the like. Covered and coating material, however, already in the foam form

can thus have been connected to the foam body by the one placed on the model.

Molding material can no longer be shown. At the same time, those with the inventive

In this way, the formation of limited coated models when used

Zungslinien, imprints or the like, as they are in the 5 unbound, loose molding sands, because the stabilizing

Use of combustible coating materials, the coating is subject to slippage of the molding material

especially when covering edges, running when pouring the melt and thus likewise

fertilize or the like of the foam model in the form - the occurrence of defects on the casting to prevent

sand and thus occur on the later casting.

avoided. Through the use of such models with the required coating, the tivic view of a model provided with the claimed coating during casting is a part of the molding material - Details of the invention can be seen,
Chen of the casting. The lost model 1 consists of each other

In a further development of the invention, there is definitely 15 welded particles 2 of a foamed one

possible, models only partially in such places with plastic, for example made of expanded poly-

to provide these coatings on which, such. B. to styrene granules and is permeable to gas

Corners, splices or the like, a particularly unfavorable coating 3 made of heat-resistant, fireproof inorganic

permanent surface quality of the casting clad to niche fiber fabric. Due to the

is expected. The model will be mechanically applied in front of the 20 coating

Finally, coatings of this type can also damage, in particular by turning them out find in the production of reproduction breaks some not sufficiently welded ben irregular, spherically curved surface foam particles from the model surface such as can arise, for example, when using master model molds or during transport, len, if the foam model in itself is preserved and so the molding sand can penetrate into ter way, by means of a pourable or pourable joint, the defects that have arisen in this way are middled made of foam granulate and binder. Furthermore, the gas permeability of the is. The high mechanical Fe fabric allows a perfect deduction of the gassing of the enveloping material, e.g. B. pyrolysis resulting from the decomposition of the foam material Made of fiberglass fabric that ensures the stability of the on 30 segase.

Parts manufactured in this way are still considerably stiffened. The cover for stiffening the foam body can advantageously vervon directly with it Transitions, roundings at corners or closely bound or else with per se known binding elements of the model, in particular by filling it in. The binders that are also used to Additional cuts, such as strips or reinforcement of the fiber fabric, can serve as a sol-like thing more, which may be gasified by the liquid melt and water-repellent len are set to be stronger. so that the gas permeability of the coating

The attachment of the coating materials on the len.

Foam bodies are usually made by pouring the liquid melt into one

gluing. 4 ° opening 4 in the coating layer of the model exposed.

In the production of foam models for let, through which the casting material in the foam

the mass production of castings can penetrate the body of material and gasify it.

1 sheet of drawings

Claims (3)

stands, which makes the above-described rather complex claims: reworking of the model necessary. By applying such pore-filling 1. Inorganic coating based on an agent, although the above disadvantages are avoided, Refractory fiber material for a gasifiable from 5, however, the filling of the holes in the all-over-foamed Plastic existing casting molds can be done by spatula and is therefore right dell, characterized in that he is laborious. is designed as a fabric. Another suggestion is a film-like one 2. Inorganic coating according to claim 1, coating made of a substance which at the inlet of the characterized in that the coating forms the melt material faster than the foam only partially covered. burns and gasifies, such as collodion 3. Use application of inorganic coating. However, there is a risk of neglect here Claim 1 for a casting model in flowable puffings and an associated destruction like molding material. the mold when using larger amounts of the 15 coating material. It has also been proposed to use tissue paper to stretch over the model surfaces and onto them Way to secure the model against the molding material. However, this material is resistant to moisture The invention relates to an inorganic excess which is very sensitive and thus often leads to wrinkles on the basis of a refractory fiber material for formations that are transferred to the molding material a gasifiable, made of foamed plastic and also the surface quality of the later cast-up casting model and its application. Affect the piece. When touching finely divided The tissue paper can darrials with coatings based on a fireproof fiber material for gasifiable from foamed plastic 25 lose beyond its easy gasification existing casting models to carry out the full and, as it has been shown in the meantime, to deform casting are already known. Lead through the manifestations of tongue. Application of certain coating materials to the surface to remove the disadvantages mentioned the known foam models are already known or proposed surface oils Unevenness, holes or the like, as they were in the treatment of lost casting models For example, in the case of the generally metal-cutting still thin foam sheets with which Manufacture of the models by inadvertent removal also clad the surfaces of the models If individual foam particles break down, this can be suggested. This creates a such as imperfections, which are particularly easy to gasify the coating material in the model material itself are to be eliminated. In this way, 35 rials are created when a smooth model surface is formed the penetration of the molding sand into the surface is guaranteed. However, here is also the use lost model during molding prevents the need for an additional flame-retardant coating and thus the formation of blowholes. or the like in the surface of the later casting. All those previously treated in this way are lost. However, casting models often lead to deterioration In order to produce particularly smooth surfaces on the casting, which are caused by the obtained, it has therefore already been proposed to prevent the liquid melt from penetrating into the molding material Rene models made of foamed plastic with thin conditionally after the gasification of the coating material to cover layers of wax that will become. To such a penetration of the melt To prevent pouring of the melt and the associated 45, it is common to use the appropriate Mo gasification of the foam to liquefy, in the dents, in addition to the coverings described, additional foam penetrate and thus to a perfect borrowed with powdery or granular refractories free filling of the resulting casting cavity means, such as the known Schlichtemateriamit the liquid melt lead. lien, through which the occurrence of deterioration Such coatings, which is largely prevented by 50 tinging phenomena. A Immersing the foam model in a liquid release from this conventional two-layer wax melt are obtained, but have the structure of the coating material of the foam moeine different layer thickness distribution of the dell has therefore not been possible up to now for these reasons Covering material, formation of tropical reliefs possible. or the like, which only through a subsequent me- 55 object of the invention is to develop the Mechanical post-processing must be corrected- extremely cumbersome two-layer structure of the sen, so that perfect castings are obtained. known coatings by creating a mo- Furthermore, from the German patent specification, dells should be replaced with a single-layer coating.
1 185 339 a fireproof porous coating for gasification bare models made from a hardenable binder and 60 cast models made from synthetic foam with a gas-permeable Known fillers. organic coating on the basis of a refractory Furthermore, a method for smoothing the fiber material has been achieved in that Surface of lost casting models and a corresponding cover is designed as a fabric. The pouring in Model suggested that only at the deeper opening for the melt and possibly at the molar end Place its surface with slightly 65 dell adjoining risers or the like. and / or gasifiable substances, such as by-; which is not covered. This will put the on For example, wax is filled without causing any unevenness in the model surface coherent, uneven film like that when joining individual parts of the model