Valve Body Casting
The casting of the valve body is an important part of the valve manufacturing process, and the quality of the valve casting determines the quality of the valve. The following introduces several casting process methods commonly used in the valve industry:
Valve body sand casting:
Sand casting commonly used in the valve industry can also be divided into: wet sand, dry sand, water glass sand and furan resin self-hardening sand according to different binders.
(1) Green sand is a molding process method with bentonite as a binder.
Its characteristics are: the finished sand mold does not need to be dried or hardened, the sand mold has a certain wet strength, and the sand core and shell have better concessions, which is convenient for cleaning and falling sand of castings. The molding production efficiency is high, the production cycle is short, the material cost is low, and it is convenient to organize the production line.
Its shortcomings are: castings are prone to defects such as pores, sand inclusions, and sticky sand, and the quality of castings, especially the internal quality, is not ideal.
Valve body precision casting:
In recent years, valve manufacturers have paid more and more attention to the appearance quality and dimensional accuracy of castings. Because good appearance is the basic requirement of the market, it is also the positioning benchmark for the first machining process.
The commonly used precision casting in the valve industry is investment casting, which is briefly introduced as follows:
(1) Two process methods of investment casting:
①Using low-temperature wax-based mold material (stearic acid + paraffin), low-pressure wax injection, water glass shell, hot water dewaxing, atmospheric smelting and casting process, mainly used for carbon steel and low-alloy steel castings with general quality requirements, The dimensional accuracy of castings can reach the national standard CT7-9.
②Using medium temperature resin-based mold material, high-pressure wax injection, silica sol mold shell, steam dewaxing, rapid atmospheric or vacuum smelting and casting process, the dimensional accuracy of castings can reach CT4-6 precision castings.
