Lost foam casting process

Abstract

The invention discloses a last foam casting process which sequentially comprises the following steps: a, manufacturing models; b, combining the models of which the sizes and the shapes are similar to those of a cast piece into a model group, coating a fireproof layer, and drying; c, burying the dried model group into a sand box, vibrating to solid the sand box, and covering a plastic cloth; d, casting to form under the action of negative pressure; e, after the casting is completed, uncovering the plastic cloth, continuously vacuuming for minutes till the surface of the cast piece is hardened at the negative pressure the same as that of the step c, sufficiently cooling, and turning over the sand box to take out the last foam. The last foam casting process has the advantages that the tissue structure of the cast piece is changed, the crystalline grain is fine and small, the mechanical property of the cast piece is improved, the chemical components are relatively qualified, and the coating layer of the cast piece can be relatively thoroughly peeled off.

Description

technical field [0001] The invention relates to a casting process, in particular to a casting process of vacuum lost foam. Background technique [0002] The traditional sand casting process has to go through manufacturing model, manufacturing core box, core bone preparation, sprue preparation, sand preparation, core sand preparation, sand box preparation, paint preparation, core molding, box closing, pouring, sand cleaning, grinding Castings can only be produced through a series of technological processes such as sprue gate and shovel flash removal. This kind of process steps is more complicated, because the combination of cores in the process will cause errors, and burrs and flashes must be dealt with after core removal, which increases the mechanical treatment procedures, and sometimes waste products appear. In addition, sand cleaning and grinding often cause environmental damage. pollute. [0003] The lost foam casting process is already a mature technology. The traditi...

AI Technical Summary

Problems solved by technology

The traditional lost foam casting process believes that in order to ensure that the box does not collapse, the vacuum degree must be reduced for several minutes while the plastic cloth does not move. This is a misunderstanding in the traditional lost foam casting process; the traditional lost foam casting process after casting There is a large stress inside the casting. In order to solve the characteristics of the stress inside the casting, the traditional process adopts a separate failure treatment after the casting process is completed; in addition, due to the slow cooling speed of the casting surface in the traditional process, Part of the residual carbon element after the lost foam gasification is easy to infiltrate the casting from the outside to the inside, resulting in changes in the chemical composition of the casting, changes in the microstructure of the casting, and changes in performance, resulting in castings that do not meet the requirements