VERFAHREN ZUM HERSTELLEN EINER VENTILHUELSE

摘要

A method of manufacturing a valve sleeve which is combined with a valve rotor to form a hydraulic rotary valve comprises a first step of expanding one end of a cylindrical member, a second step of forming a plurality of axial grooves in the internal surface of the cylindrical member while leaving its opposite ends intact, and a third step of restoring the expanded portion to its original diameter which it assumes before the expanding step.