Large-size impeller processing technique in precise casting

Abstract

The invention provides a large-size impeller processing technique in precise casting and belongs to the technical field of special metal article processing. The large-size impeller processing technique comprises the following steps of: firstly, utilizing plastic foam as a model, integrally adhering a pouring system foam mould with a casting foam mould to form a module, and then, coating a plurality layers of refractory materials on the outer surface of the module, and sintering to remove the pouring system foam mould and the casting foam mould to form a thin ceramic shell with a die cavity; putting the prepared thin ceramic shell in a sand box, guaranteeing the minimal distance from the outer wall of the thin shell to the wall of the inner cavity of the sand box to be 40-50mm, and making a pouring gate cup on the thin shell be 40-70mm higher than the sand box, filling resin sand between the sand box and the thin shell, and vibrating the sand box while filling the resin sand until the sand box is fully filled; heating the sand box to 350-500 DEG C; and finally pouring molten metal through a stopper ladle. The large-size impeller processing technique provided by the invention can both guarantee the casting dimension precision and good smoothness, but also guarantee no cold shut or crack on the casting, thereby greatly reducing the finishing workload of the casting, reducing the production cost, shortening the working period and improving the casting quality stability.

Description

technical field [0001] The invention relates to the processing of a specific metal object, in particular to a processing technology for large impellers in precision casting. Background technique [0002] With the popularization of large equipment and the development of nuclear power industry, the use of medium and large impellers is becoming more and more common, and the shape of impellers is becoming more and more complex. Medium and large impellers refer to impellers with a weight of 150kg-1000kg and a diameter of 700mm-1500mm . In order to obtain better hydrodynamic performance, the requirements for dimensional accuracy and surface roughness of medium and large impellers are getting higher and higher. The traditional precision casting process is as follows: firstly, plastic foam is used as a model, and the gating system foam mold and the casting foam mold are bonded together to form a module; then several layers of refractory materials are coated on the outer surface of ...

AI Technical Summary

Problems solved by technology

Due to the limitation of size, the production of slightly larger impellers by the lost foam process is always plagued by casting defects such as cold shuts and cracks, and at the same time brings a considerable workload to the workers.

[0003] In the traditional resin sand casting process, the precision of the casting has become the biggest heart problem.

Most foundries produce large impellers through resin production. Only after repeated finishing and grinding and repeated size repairs can they get qualified castings, which wastes a lot of manpower and material resources, and at the same time forces the production cycle to be greatly lengthened.

However, the surface roughness of the impeller still cannot meet the requirements

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