Vacuum, gravity and precision casting method with metallic mould

Abstract

A vacuum-gravitational precise casting technology with metallic mould includes such steps as preparing metallic mould, putting it in a cover, sealing the cover, vacuumizing, pouring molten metal while vacuumizing, immediately taking the cast workpiece out and cooling.

Description

technical field [0001] The invention belongs to a casting method, in particular to a metal mold gravity casting method. Background technique [0002] Casting is one of the most widely used forming methods in today's machinery manufacturing industry, including metal mold casting and sand mold casting. [0003] Metal mold casting is to inject molten metal into a metal model under the action of gravity, and obtain castings through condensation forming. Its advantages are: [0004] 1. The metal mold has high thermal conductivity and heat storage, and the cooling speed of the molten metal in the mold is fast, and it has a forced chilling effect, so the grains of the casting are refined, the structure is compact, and the mechanical properties are significantly improved. [0005] 2. High dimensional accuracy and low surface roughness. [0006] 3. The same mold can be used repeatedly without additional molding, the production process is simplified, the efficiency is high, and the...

AI Technical Summary

Problems solved by technology

[0008] However, the metal mold casting method is carried out under normal pressure, and the castings produced often have the following defects: (1) Because the metal mold itself has no air permeability, the exhaust channel is small, and it is easy to be blocked by paint and metal, resulting in difficulty in exhausting, Castings are prone to porosity

(2) Due to the large chilling effect of the metal mold, the molten metal cools down quickly, and the fluidity and shrinkage become poor. Insufficient pouring and internal looseness are prone to occur at the corners of the casting, and it is not easy to produce thin-walled castings,) especially the mold The gas in the cavity expands rapidly under the action of the heat of the molten metal, forming a large gas back pressure, and it is more likely to produce casting defects such as pores, cold shut and insufficient pouring under the condition of poor exhaust

(3) Since the metal type has no concession, the casting is easy to crack during the solid shrinkage stage

Therefore, there are strict requirements on the design of the metal mold, inner surface coating, preheating temperature, pouring temperature, pouring speed, mold opening time and other process parameters, which are not easy to control

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