Large impeller precision casting mold and system and large impeller low pressure casting system

Abstract

The invention discloses a large impeller precision casting mold and system and a large impeller low-pressure casting system. The large impeller precision casting mold comprises an upper mold and a lower mold which are correspondingly arranged in an up-down manner; a forming element is arranged in a mold cavity formed by the upper mold and the lower mold; a mold core used for forming an inner cavity and blades of an impeller is arranged on the upper portion of the forming element; the upper mold is provided with a first cooling part used for cooling the interior of the impeller; the top of the upper mold is provided with a plurality of second cooling parts used for performing air injecting cooling on the upper mold; and the lower surface of the upper mold is provided with a plurality of exhaust parts used for performing exhausting. An annular groove and a venting plug are arranged in the upper mold to improve exhausting, a cooling ring and a cooling cone are used for increasing the casting cooling speed, and the forming element is used at the bottom of the gypsum mold core and is favorable for heat preservation of bottom molten aluminum and feeding of a casting. The overall casting process of the thin-wall large-size impeller can be achieved, the forming quality is good, and precision is high.

Description

technical field [0001] The invention belongs to the technical field of precision casting, and in particular relates to a precision casting mold and system for a large impeller and a low-pressure casting system for a large impeller. Background technique [0002] Centrifugal compressors or centrifugal pumps are used to provide pressurization for various fluid flows. This type of compressor or centrifugal pump contains an impeller. When the impeller rotates, the fluid enters in the axial direction, and then accelerates into the circumferential and radial directions. The high-velocity fluid enters the diffuser, and the high-pressure fluid is output after the speed is converted. For this type For compressors or centrifugal pumps, the impellers used are generally precision cast large thin-walled impellers. [0003] When using the low-pressure casting method to cast the impeller, the cooling process needs to meet a certain cooling gradient. The ideal cooling state is from top to b...

AI Technical Summary

Problems solved by technology

Existing casting molds for impellers are generally set as an upper mold, a lower mold and a mandrel. When using the existing casting molds for casting processing of large thin-walled impellers, it is often impossible to achieve the ideal structure from the top to the bottom due to the unreasonable structure of the mold itself. The cooling sequence and cooling effect from the bottom to the inside, the cooling speed of the impeller casting during the entire cooling process is not uniform, the cooling degree is not uniform, and the final formed impeller casting has defects such as shrinkage and porosity;

[0004] Due to the large diameter of the large thin-walled impeller, the wall of the impeller is thin, and the thinnest part of the blade is about 1.2mm. When the existing casting mold is casting a large impeller, the air permeability of the mold is poor, resulting in poor exhaust during the casting process. When the casting solution is filled into the mold, resistance will be generated, resulting in insufficient pouring of the impeller casting, or the gas in the mold cannot be discharged, and the phenomenon of molten metal liquid pocket gas will occur, which will cause defects such as pores and sand holes in the impeller casting, and the microstructure and performance will be low. impeller casting quality;

[0005] Due to the small thickness of the blade of the large thin-walled impeller, the shape of the blade is distorted, and the structure is complex. When using the existing impeller casting mold for casting, it is difficult to mold, and it is difficult to ensure the dimensional accuracy and surface roughness of the impeller casting. Under the premise of cooling the impeller casting, the shrinkage cavity that may occur in the large thin-walled impeller casting cannot be further fed, and the final impeller casting has a low yield and poor quality

[0006] Moreover, when using the existing impeller casting mold for low-pressure casting, it is often difficult to achieve a good cooling gradient

Usually, the internal structure of the impeller, such as the surface of the blade and the inner cavity, is relatively smooth, but the shrinkage and porosity of the T-shaped hot joint at the root of the blade is serious, and qualified castings cannot be obtained even after repeated improvements.

When casting a large thin-walled impeller, due to the increase in diameter, the size of the mold structure itself also increases. It is more difficult to meet a certain cooling gradient when the entire mold structure is cooled, and the final impeller casting cannot meet the requirements of normal use. need

Images