A shell-making process for easily collapsible shells

Abstract

The invention discloses a shell forming process for a high-collapsibility shell. The shell forming process comprises the steps of pressing a waxy model of a part to be produced; coating the waxy modelwith zircon slurry, then spreading zircon sand and conducting air drying; coating the waxy model with mullite slurry, spreading mullite sand on the surface and conducting air drying; coating the waxymodel with the mullite slurry repeatedly a preset number of times, spreading the mullite sand and conducting air drying, wherein the content of mullite powder in the mullite slurry is gradually reduced, the adopted mullite sand gets thicker and thicker, during first or second repetition, the mullite sand is replaced with fused quartz sand, sponge is adopted for plugging holes of the waxy model after air drying, after last coating of the mullite slurry, the mullite sand is not spread, and direct air drying is conducted; melting wax in a mold shell to make the wax flow out; conducting high-temperature roasting on the mold shell. Through the improvement of the process, the problem that after a porous metal cast part is produced, a mold shell material remaining in the holes of the part is noteasy to take out is solved, and the part is not damaged; thus, the production efficiency is improved, and the production cost is reduced.

Description

technical field [0001] The invention relates to the field of silica sol precision casting technology, in particular to a shell-making process for easily collapsible molded shells. Background technique [0002] In the production of investment precision castings, many metal castings are melted by intermediate frequency furnace at high temperature, and then poured into the model shell to be cooled and formed; the selection of shell material is of great importance to the quality, production cost and efficiency of metal castings influences. At present, the shells of domestic civil and commercial castings generally use silica sol shells, usually using kaolinite as the refractory sand and powder of the back layer. [0003] Kaolinite clinker includes coal gangue, coke gemstones, etc. Although these materials are common, widely sourced and have good process performance, the shelling performance of the castings is poor. If the metal parts produced have holes, after the castings are p...

AI Technical Summary

Problems solved by technology

[0004] In order to overcome the above-mentioned defects in the prior art, the technical problem to be solved by the present invention is to provide a shell-making process for easily collapsible shells, so that after the metal castings with holes are poured and formed, the residual shell material in the casting holes Easy to remove without causing other quality problems in castings

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