SU1532194A1 - Die-casting mould for refractory alloys - Google Patents

Abstract

The invention relates to foundry, in particular, to injection molding of refractory alloys. The purpose of the invention is to increase the life of the mold. Each half-form consists of three layers: inner 3 intermediate 4 and outer 5. The inner layer is made of porous refractory ceramics, such as aluminum or boron nitrides, the intermediate layer is made of metal with a grid of holes 6 and grooves 7, and the outer layer is also made of metal. Cavities 9 for a fusible alloy are made in the outer layer, connected by channels 11 with intermediate 4 and inner 3 layers. Before operation, the mold is heated to a temperature above the melting point of the low-melting alloy, the low-melting alloy is poured into the cavity 9, and the cavity 9 is connected via a pipeline 10 to a source of gas pressure. Under the action of gas pressure, the low-melting alloy penetrates into the grooves 8, the holes 6 and the pores of the inner layer 3. The mold is cooled with compressed air, the gas pressure is released and the mold is ready for operation. 3 hp f-ly, 1 ill.

Description

heat to a temperature above the melting point of the low-melting alloy, sink into the cavity 9 the low-melting alloy and connect the cavity 9 by means of a pipeline 10 to a source of gas pressure. Under the influence

the gas pressure low-melting alloy penetrates into the grooves 8, the holes 6 and the pores of the inner layer 3. The mold is cooled with compressed air, the gas pressure is relieved and the mold is ready for operation. 3 hp f-ly, 1 ill.

The invention relates to foundry, in particular, to injection molding of refractory alloys.

The purpose of the invention is to increase the service life of the mold.

The drawing shows the mold cut.

The mold consists of left 1 and right 2 half-molds connected to a pressing chamber. Each half-form consists of an inner 3, intermediate 4, and outer 5 layers. The inner layer 3 is made of refractory ceramics (for example, aluminum nitride or boron) with pores (capillaries) through the thickness. The intermediate layer 4 is provided with a grid of through holes 6, and a mesh of grooves 7 and 8 is applied along the outer and inner surfaces. In the outer layer 5 there is a cavity 9 connected by a pipeline 10 with a gas pressure source, a system of channels 11 fc of the grooves of the intermediate layer 5. With this at the temperature above the melting point of the low-melting metal, the fusible metal from channels 11 easily penetrates into the grid of the grooves 7 and 8, the holes 6 and the capillaries of the inner layer 3, and together with the cavity 9 form a single lock thuja system. To overcome the capillary forces, the excess gas pressure supplied through the pipeline 10 is used. The gas pressure value depends on the material of the inner layer, the size of the pores and the operating temperature of this layer can be determined by known dependencies and is 0.55-5.5 MPa.

The inner layers 3 of each of the half-molds form a working cavity 12 of the mold. The inner and intermediate layers are fastened with strips 13 secured to the molds with screws. Pushers 14 are designed to push the casting out of the right half-mold 2. As a result, 5

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The filling systems with the fusible metal (for example, aluminum or copper) of the capillary system, the holes 6, the grooves 7 and 8, and also the channels 11 eliminated the contact gaps in the three-layer mold, which improves the conditions of its strength work, since behaves as one. The conditions and its thermal work are improved, since due to the filling of pores and gaps with low-melting metal, contact thermal resistances are eliminated, which makes it possible to reduce the magnitude of thermal shock during casting, since its effective thermal conductivity significantly increases with metal-filled pores of the inner layer.

The choice of ceramics from aluminum or boron nitrides is based on the fact that they have a melting point of 2232 and 2732 ° C, respectively, and when they come into contact with atmospheric oxygen in a heated state, they form a tufflanked protective oxide film that plays an important role in protecting the working surface of the mold -chemical interaction with a liquid metal flow during pressing.

The implementation of the inner, intermediate and outer layers of materials, the temperature expansion coefficients of which increase from the inner to the outer layer, helps to reduce the temperature stresses in the mold during casting. So, for the inner layer of aluminum nitride, the coefficient of temperature expansion is - | for the intermediate layer of low carbon steel - 1.2-10, and for the outer layer of alloyed steel 1, 8-10

Before starting the operation, the mold is heated to a temperature slightly higher than the melting temperature of the low-melting alloy, the low-melting alloy is poured into the cavity 9, and excess gas is fed through the pipeline 10

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pressure and fill the fusible alloy with the holes and grooves of the intermediate layer 5 and the pores of the inner layer A before the appearance of droplets of the fusible metal on the working surface of the mold. After that, the working surface of the mold is blown with compressed air, knocking it down, relieving gas pressure, cleaning the working surface from droplets of low-melting metal, and the mold is ready for operation.

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Making molding inserts of three slurry, connected by a low-melting metal, improves the strength of the ceramic layer, reduces thermal loads, which allows to increase the service life of the mold when casting refractory alloys.

Claims (4)

Claim 1. Injection mold for casting under pressure of refractory alloys, the formative parts of which are made of inner, intermediate and outer layers, distinguished by the fact that, in order to increase the duration 94 the inner layer is made of porous refractory ceramics, the intermediate layer is made of metal with a grid of through holes and grooves on the side surfaces, and the outer layer is made of metal with channels on the surface in contact with the intermediate layer, with the pores of the refractory inner layer, holes and the grooves of the intermediate layer and the channel of the outer layer are filled with low-melting metal. 2. A mold according to claim 1, characterized in that a cavity for the low-melting metal is made in the outer layer, connected to channels on its surface, and the cavity is connected by a pipeline to a source of gas pressure. 3.Press form on PP. 1 and 2, characterized in that the coefficients of thermal expansion of the layers increase from the inner layer to the outer layer, 4.Press form on PP. 1-3, characterized in that the inner layer is made of aluminum or boron nitrides.