Casting process for integrally casting a vacuum pump impeller by using large nodular cast iron

Abstract

The invention relates to the technical field of casting of equipment parts, and discloses a casting process for integrally casting a vacuum pump impeller by using large nodular cast iron. The casting process comprises the following steps that S1, a blade of the vacuum pump impeller is segmented, and a structure for splicing a required integral spiral blade is designed on each section of the blade of the vacuum pump impeller, and then a forming mold for forming foam patterns of each section of the blade of the vacuum pump impeller is machined by adopting existing equipment. According to the casting process for integrally casting the vacuum pump impeller by using the large nodular cast iron, the nodular cast iron is integrally casted, a sand box is opened after a casting is completely cooled, and heat treatment is carried out after sand cleaning and casting head removal, such that the vacuum pump impeller integral casting which is compact in internal structure and meets the requirement on dimensional accuracy is obtained, the impeller is high in size precision, uniform in equal division and free of welding seams, an inner cavity of a hub is free of sand burning and sintering, the casting structure is compact, the welding stress influence is eliminated, and operation is stable.

Description

technical field [0001] The invention relates to the technical field of casting of equipment parts, in particular to a casting process of a large ductile iron integral casting vacuum pump impeller. Background technique [0002] Vacuum pump is a common device in daily life. The impeller is a relatively important component of the vacuum pump. The impeller of the vacuum pump has high dimensional accuracy, thin blades and thick hubs at both ends, and complex structure, so it is difficult to cast as a whole. Therefore, it is usually formed by welding steel plates and divided into two sections. The manufacturing process of splicing and molding after casting. [0003] The existing impeller formed by welding steel plate needs to go through blanking, welding groove processing, heat treatment, mechanical processing and other processes. The manufacturing cycle is long, and it is difficult to ensure the quality of the weld seam during welding. As a result, equipment accidents are prone t...

AI Technical Summary

Problems solved by technology

[0003] The existing impeller formed by welding steel plate needs to go through blanking, welding groove processing, heat treatment, mechanical processing and other processes. The manufacturing cycle is long, and it is difficult to ensure the quality of the weld seam during welding. As a result, equipment accidents are prone to occur due to stress concentration when the impeller is running at high speed. , when the steel plate is assembled and welded, the equal division of the blade and the size of the whole impeller are not easy to control, and the deformation caused by welding is difficult to correct. Low, short service life, due to the special structure of vacuum pump impeller castings, generally only vertical pouring method can be used for casting, although the thick and large hub that is finally solidified on the upper part can be fed by a riser to make the upper structure dense , but it is impossible to take feeding measures for the thick and large hub that is finally solidified in the lower part, and the metal liquid cannot be fed, and finally shrinkage cavities and shrinkage porosity are formed. It is completely surrounded, and the general molding sand used is difficult to resist the high temperature of about 1650°C during pouring and solidification and is sintered, which makes it difficult to clean up the casting after molding, resulting in scrap, and the existing manufacturing process has high labor intensity and low production efficiency. The vacuum pump impeller has defects such as unstable forming quality and large welding combination error, and the wear resistance of the vacuum pump impeller is insufficient, so surface coating treatment is often required. The coating is also easy to fall off during use, so it is still not effective for a long time. Improve wear resistance of vacuum pump impeller