Machine tool castings.
Machine tool castings can be called large castings.
One, machine tool bed standard: GB9439 - 88
In two, the bed characteristics:
( 1) wear resistance and shock resistance. As a result of graphite in cast iron are conducive to the lubrication and oil storage, so good wear resistance. Also, because the graphite in the presence of shock eliminating performance superior to steel.
( 2) good technological properties. As a result of grey cast iron with high carbon content, close to eutectic composition, the relatively low melting point, good fluidity, low shrinkage, thus suitable for casting of complicated structure or thin wall castings. In addition, due to the easy formation of graphite machining chip breaking, so gray iron machinability is superior to steel.
In three, the hardness and tensile strength of grey cast iron: the relationship between hardness and tensile strength between, there are corresponding relationship, the empirical formula for:
In 1, when O ≥196N/mm ㎡.
HB=RH ( 00+0 4380b ( B1 ) fly )
In 2, when 0 ≥796N/mm ㎡.
HB=RH ( 44+O 7240b ) ( B2 ) type of relative hardness (RH ) value of the main raw material, melting technology, processing technology and casting cooling rate determined by.
Four, use of resin sand casting casting machine bed has the advantages
1, resin sand has good stiffness, casting early sand high strength which has the condition to use the cast iron of graphitizing expansion during solidification process, effectively eliminate the shrinkage hole, shrinkage, realization of grey cast iron, ductile iron castings, small riser casting.
2, casting in the production of polystyrene foam pattern application furan no-bake resin sand molding feed. When molten metal is poured into the mold, plastic pattern in high temperature liquid metal rapidly under the action of gasification, combustion vanishes, the liquid metal instead of plastic foam to occupy the position, cooling coagulated with the appearance shape same solid pattern casting.
3, relatively speaking, lost foam casting for single or small batch production of automobile covering parts, machine tool bed and other large mold compared with traditional sand has a lot of advantages, it not only eliminates the expensive wood type cost, and convenient operation, shorten the production cycle, improve production efficiency, has a high dimensional accuracy, the machining allowance small, good surface quality and other advantages.
