Vacuum pump impeller integral casting process

Abstract

The present invention provides an integral casting process of vacuum pump blade wheel. It uses copper alloy to make the integral pattern prepared by using intermediate partition board, blade and wheel hub undergo the processes of numerically-controlled processing and moulding treatment. Its sand core is placed in lower mold, on the sand core of internal cavity place a ceramic core is set, upper blade wheel and upper wheel hub top portion are equipped with riser, undersurface of lower wheel hub and shaft hole place are equipped with external chill, the internal running channel set in lower blade bottom end is communicated with straight running channel in the mold. The molten metal can be fed into internal running channel via straight running channel, then passed through the lower blade bottom end and introduced into mold cavity to make bottom casting operation, when the molten metal is reached to riser top from bottom to top, an exothermic mixture is added into riser interior, after the casting is cooled, the molding box is opened, sand is removed and the casting is undergone the process of heat treatment.

Description

technical field [0001] The invention belongs to the technical field of casting, and in particular relates to an integral casting process of a vacuum pump impeller. Background technique [0002] Due to the high dimensional accuracy of the vacuum pump impeller, the blades are thin and the hubs at both ends are thick, and the structure is complex, so the overall casting is difficult. Therefore, the manufacturing process of welding and forming of steel plates and casting in two stages and then splicing and forming is usually adopted. [0003] The impeller formed by welding of steel plates needs to go through processes such as blanking, welding groove processing, heat treatment, and mechanical processing, and the manufacturing cycle is long. It is difficult to ensure the quality of the weld seam during welding, so that equipment accidents are prone to occur due to stress concentration when the impeller is running at high speed. When the steel plates are assembled and welded, th...

AI Technical Summary

Problems solved by technology

It is difficult to ensure the quality of the weld seam during welding, resulting in equipment accidents due to stress concentration when the impeller is running at high speed

When the steel plate is assembled and welded, the blade equalization and the size of the overall impeller are not easy to control, and the deformation caused by welding is difficult to correct

Therefore, after the steel plate is welded and formed, the equal parts of the blades are uneven, and the dimensional accuracy of the impeller is poor, which makes it unstable after installation, with low efficiency and short service life.

It is more difficult for impellers welded with general plates to meet the needs of special operations such as corrosion resistance and wear resistance

[0004] The impeller is cast in two stages and then spliced. When welding, the splicing surface needs to be increased, and there are many consumables, so the weight of the impeller is increased and the working efficiency of the equipment is reduced.

Moreover, when splicing, the splicing surfaces are difficult to seal, and the working medium easily enters the inner cavity of the impeller hub and corrodes the main shaft and bearings, resulting in a short service life of the vacuum pump

[0005] Due to the special structure of vacuum pump impeller castings, generally only the vertical pouring method can be used for casting. For the thick and large hub that solidifies last at the top, although the riser can be set to make the upper structure dense, but for the last at the bottom The solidified thick hub cannot be fed by the metal liquid because of the inability to take feeding measures, and finally forms shrinkage cavities and shrinkage porosity

During casting, the inner cavity of the impeller hub of the vacuum pump is completely surrounded by high-temperature metal liquid, and the general molding sand used is difficult to resist the high temperature of about 1650°C during pouring and solidification and is sintered, making it difficult to clean the casting after molding, resulting in scrap

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