Valve casting process method introduction

Valve casting process method introduction

The casting of the valve body is an important part of the valve manufacturing process,  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:

Sand casting:

Sand casting commonly used in the valve industry can also be divided into: wet sand, dry sand, water glass sand  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  need to be dried  hardened, the sand mold has a certain wet strength,  the sand core  shell have good concessions, which is convenient for cleaning  falling sand of castings. The molding production efficiency is high, the production cycle is short, the material cost is low,  it is convenient to organize the production line.

Its shortcomings are: castings are prone to defects such as pores, sand inclusions,  sticky sand,  the quality of castings, especially the internal quality, is  ideal.

(2) Dry molding sand is a molding process with clay as a binder,  a little bentonite can improve its wet strength.

Its characteristics are: the sand mold needs to be dried, it has good air permeability, it is  easy to produce defects such as sand washing, sand sticking,  pores,  the inherent quality of the casting is better.

Its disadvantages are: sand drying equipment is required,  the production cycle is long.

(3) Water glass sand is a molding process method with water glass as a binder. Its characteristics are: water glass has the function of automatic hardening after encountering CO2,  can have various advantages of gas hardening method modeling  core making, but There are disadvantages of poor shell collapsibility, difficulty in sand cleaning of castings,  low recycling rate of used sand.

The mixing process of furan resin no-bake sand: The resin no-bake sand adopts a continuous sand mixer,  the raw sand, resin, curing agent, etc. are added in sequence  mixed quickly,  can be mixed  used at any time.

The order of adding various raw materials when mixing resin sand is as follows:

Raw sand + curing agent (p-toluenesulfonic acid aqueous solution) - (120 ~ 180S) - resin + silane - (60 ~ 90S) - sand production

In recent years, valve manufacturers have paid more  more attention to the appearance quality  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.