A kind of sand core and its preparation method and casting mold

Abstract

The invention relates to a sand core, a preparation method thereof and a casting mold. The preparation method includes: 1) preparing the core bone according to the structure of the sand core; 2) forming an intermediate material layer on at least part of the outer surface of the core bone; 3) placing the core bone in a sand core mold and filling it with refractory filler Sand molding to obtain the original sand core blank, and drying the original sand core blank; 4) roasting the dried sand core blank to obtain a sand core; wherein the roasting temperature in the roasting treatment is higher than that of the intermediate material Action point temperature. Since the roasting temperature of the original sand core blank exceeds the action point temperature of the intermediate material, the intermediate material will not produce resistance to the expansion of the core bone during roasting, thereby avoiding the phenomenon of cracking, deformation and scrapping of the sand core.

Description

technical field [0001] The invention belongs to the field of casting molding, and in particular relates to a sand core for casting. Background technique [0002] With the rapid development of aviation, aerospace, ships, weapons, petrochemical and other fields, the demand for metal castings such as titanium and titanium alloy castings is also increasing. Sand cores for titanium and titanium alloy castings can be used not only in the field of sand casting technology, but also in the fields of graphite processing casting due to their advantages of low cost and good yield. However, the existing sand cores for titanium and titanium alloy casting, especially for large sand cores, are prone to cracking and deformation during the preparation process due to their structural characteristics such as large sand core profile, large sand core thickness, and heavy weight. Scrap, low roasting efficiency, poor dimensional accuracy and other issues. [0003] In the prior art, the patent app...

AI Technical Summary

Problems solved by technology

However, the existing sand cores for titanium and titanium alloy casting, especially for large sand cores, are prone to cracking and deformation during the preparation process due to their structural characteristics such as large sand core profile, large sand core thickness, and heavy weight. Scrap, low roasting efficiency, poor dimensional accuracy, etc.

[0003] In the prior art, the patent application CN202725965U proposes a method for preventing cracking of the sand core by wrapping a heat-resistant soft material at both ends of the mandrel. By using the characteristic that the temperature-resistant soft material is easy to be compressed under external force, it solves the problem of Sand core cracking caused by core bone thermal expansion during pouring

However, the soft material is severely squeezed by the metal core and sand core filler during the molding stage, and the material still remains during the firing process. The metal core will expand thermally during firing, and the soft material will be difficult to be further compressed. To avoid the cracking problem of sand core

Images