CS241694B1 - Filling chamber for metal casting - Google Patents

Abstract

The device relates to foundry, namely to casting metals with a high melting point under pressure and solves the problem of reducing the cooling of the melt in the filling chamber. The essence of the device lies in the creation of a thermally insulating cavity between the outer and inner casing of the filling chamber, which can be vacuum or filled with thermally insulating material.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging chamber for casting metals under pressure, preventing rapid cooling of molten metal in the charging chamber.

When casting metals under pressure, especially high melting point metals, such as ferrous alloys, it is necessary to ensure that the molten metal does not cool and thus solidify in the filling chamber when it is extruded into the mold cavity.

Known charge chambers for die casting of metals, provide slow cooling of molten metal, consist of two concentric bushes, an internal housing in which the sliding pressure piston moves and made of a heat and abrasion resistant material, and an outer housing of high strength steel . Between the two sleeves there is a layer of high thermal conductivity, in which electrically heated rods are arranged to ensure heating of the filling chamber.

The disadvantage of this solution is the need of electric energy for heating the casting chamber and operational failure rate.

Other casting chambers, designed to reduce heat transfer from the molten metal within the chamber to the atmosphere, consist of an inner thin-walled sleeve of heavy-duty metals such as molybdenum, tungsten and their alloys onto which a thicker compressed metal powder layer is sintered and the outer steel sleeve is pressed. The sintered compressed metal powder layer somewhat reduces the heat transfer in the inner casing, but due to its low porosity, the thermal insulation thus formed is not sufficiently effective. In addition, the thermal expansion of the sintered layer is different from the thermal expansion of the inner surface, causing additional stresses.

The aforementioned disadvantages are minimized by the filling chamber for the pressurized metal according to the invention, characterized in that a heat-insulating cavity is formed between the inner and outer sleeves. The cavity is preferably vacuum, and in an even more preferred embodiment, at least one shielding tube is arranged around the inner housing on the vacuum chamber. The outer surface of the inner casing and the inner surface of the outer casing delimiting the vacuum cavity are provided with a glossy surface. According to another alternative, the heat insulating cavity is filled with loose, heat insulating material.

The die casting chamber of the present invention provides a substantially slower melt cooling in the feed chamber than other known embodiments and allows post-crystallization of the metallurgical process by partial crystallization in the feed chamber.

In the accompanying drawings, some embodiments of the invention are shown, in which Fig. 1 is a filling chamber with a vacuum cavity in cross-section, and Fig. 2 is a filling chamber with a heat insulating cavity, filled with a heat insulating material in cross-section.

As is apparent from the enclosed figures, the filling chamber for metal die-casting consists of an outer sleeve 2, on the inner surface of which a shoulder is formed which, when the inner sleeve 3 is pressed, forms a heat-insulating cavity 1.

The inner surface of the inner casing 3 and a portion of the inner surface of the outer casing 2 form a cylindrical chamber 6 provided with an outlet opening 7 and a melt inflow opening 8, and there is a slidingly mounted displacement piston 4 operated in a conventional manner.

The thermally insulating cavity 1 is vacuum in this case, and to more effectively reduce the heat transfer by radiation, the outer surface 5 of the inner casing 3 and the inner surface 5 of the outer casing 2 are provided with a glossy surface, i.e. silver or other glossy coating or polished. Further reduction of the heat transfer by radiation is achieved by at least one shielding tube 10 arranged in a vacuum cavity around the inner housing 3.

According to the embodiment of Fig. 2, the filling chamber for metal die casting is formed in a manner similar to that of Fig. 1, except that the heat insulating cavity is not vacuum, but is filled with heat insulating material 9, preferably poured.

In this case, the shielding tube 10 need not be used.

The molten metal poured through the pouring orifice 8 into the cylindrical chamber 6 is extruded by the discharge piston 4 through the orifice 7 into the filled mold, the heat loss from the melt during this process being substantially reduced due to the heat insulating cavity 1 disposed between the outer shell 2 and the inner shell 3.

Claims (5)

OBJECT OF INVENTION 1. A die-casting metal filling chamber, comprising an outer casing in which an inner casing of a material resistant to high temperatures and pressures is contained and forming at least part of a cylindrical cavity in which a dispensing piston is housed, characterized in that between the outer casing ( 2j and a thermal insulating cavity (1) is formed by the inner housing (3). 2. Filling chamber for metal die-casting according to claim 1, characterized in that the thermally insulating cavity (11) is vacuum. 3. Filling chamber for metal die-casting according to claim 1, characterized in that the heat-insulating cavity (11) is filled with heat-insulating material (9). Filling chamber according to Claims 1 and 2, characterized in that at least one shielding tube (10) is arranged around the inner housing (3) in the heat-insulating cavity [1]. 5. The metal injection molding chamber according to claim 1, characterized in that the outer surface (5) of the inner casing (3) and the inner surface (5) of the outer casing (2) in the thermal insulation cavity (1) are provided with a glossy surface.