CONTROL VALVE BODY FOR AUTOMATIC SPEED CHANGER AND METHOD OF PRODUCING THE SAME

摘要

A valve body where flow path grooves for hydraulic oil used for speed change operation of an automatic speed changer are formed between partition walls by forcing molten magnesium or magnesium alloy into a hollow section formed by a mold. In this process, the flow path grooves are formed by projections provided on the mold and projecting in the hollow section. Since the heat capacity of magnesium is small, the temperature variation width of the mold in a thermal cycle can be restricted to be small, and further, magnesium has no reactivity with the mold. As a consequence, the thickness of the projections on the mold can be reduced without causing degrading of the projections.