Method of making a valve sleeve

摘要

In manufacturing a tubular valve sleeve having axially extending grooves on its inner surface, the valve sleeve groove ends are closed by radially inward displacement of sleeve material, which is limited by a mandrel to minimize the formation of cracks in the material. First, a tubular member is provided which has a plurality of grooves extending axially along an inner surface of the tubular member through the axially opposite end surfaces of the tubular member. The end surfaces extend radially outward from the inner surface of the tubular member to the outer surface. Each of the axially extending grooves has a base surface located between the inner and outer surfaces. A pair of first punches are simultaneously forcefully abutted against the end surfaces, between the base surface of each groove and the outer surface. This displaces material of the end surface adjacent each groove radially inwardly of the inner surface. A mandrel inside the tubular member limits radially inward displacement of the material by engagement of the material with the mandrel.