Casting mold and forming method for box body of gearbox

Abstract

The invention provides a casting mold and forming method for a box body of a gearbox and belongs to the technical field of liquid formation of metal. The forming method comprises the following steps that precoated sand is used for core shooting, so that precoated sand blocks are manufactured, then an outer precoated sand mold layer is formed by splicing the precoated sand blocks, and the outer precoated sand mold layer and a sand core are used for forming a casting cavity of the box body of the gearbox; and finally the box body of the gearbox is manufactured through the casting mold in a low-pressure casting way. According to the specific structure of the casting mold, the sand core is located in the center of the casting mold; the casting cavity is formed in the outer layer of the sand core and mainly formed by the sand core and the outer precoated sand mold layer; an outer resin sand mold layer is arranged on the outer layer of the outer precoated sand mold layer, and the outer precoated sand mold layer and a sand box are connected through the outer resin sand mold layer, so that the casting mold is formed. According to the casting mold and forming method for the box body of the gearbox, the cavity which is formed by the precoated sand and used for large complicated castings is used for low-pressure casting for the first time, the precoated sand blocks are subjected to core shooting under pressure, high-temperature sintering formation is conducted, filling is compact, and the situations that sand filling is incompact and sand adhesion defects are caused due to human factors during resin sand molding are avoided.

Description

technical field [0001] The invention relates to a casting mold of a gearbox and a molding method thereof, in particular to a casting mold of a gearbox casing and a molding method thereof, belonging to the technical field of liquid metal molding. Background technique [0002] The existing gear box forming methods are mainly sand casting and metal casting. The sand casting cavity is generally made of resin sand. After the resin sand is molded, the resin undergoes a cross-linking reaction under the catalysis of the curing agent and hardens. The pores between the hardened resin sand and the sand are larger. The refractoriness is low. When casting, the cavity and the molten aluminum directly contact the molten aluminum and enter the surface sand gap, which is easy to produce sticky sand, which affects the quality of the casting. In order to improve the refractoriness of the cavity and avoid sand sticking, it is necessary to brush a layer of paint on the cavity; in the process of...

AI Technical Summary

Problems solved by technology

[0005] For large and complex gear box shell castings, gravity-coated sand casting is not suitable. If gravity-coated sand casting is used, the speed at which molten aluminum enters the cavity is affected by gravity and cannot be adjusted, which is prone to splashing during the filling process. And entrainment, splash and entrainment will cause defects such as cold shut and porosity in castings

At the same time, the casting is solidified under gravity, and the pressure it receives is small, which is not conducive to feeding, and the casting is prone to defects such as shrinkage porosity and shrinkage cavity

For large and complex gear box castings, it can be realized by low-pressure casting with smooth filling process, finer forming structure and better feeding effect; low-pressure casting solidifies under pressure, and the cavity must be brushed to prevent sand sticking. The existing brushing method is less efficient, and it is easy to produce brush marks after brushing, which affects the surface quality of castings

[0006] In order to ensure the dimensional accuracy and surface roughness of castings after pouring and improve the quality and yield of castings, not only must the casting mold have a certain strength, but also certain technological measures must be taken to ensure the dimensional accuracy and surface roughness of castings after pouring, so as to improve The quality and yield of castings are difficult to meet the requirements of conventional process methods

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