VALVE SLEEVE AND ITS MANUFACTURE

PURPOSE:To easily measure space between a sleeve end and a clogged position of a long groove by providing plural long grooves in the axial direction on the inner peripheral surface of a through-hole in a cylindrical valve sleeve and forming a flat part with a specific width in the clogged part of the long groove. CONSTITUTION:In a cylindrical valve sleeve 19 in which plural long grooves 6 are provided in the axial direction on the inner peripheral surface of the through-hole 2 with steps 9, a flat part 6a with a specific width is formed in the clogged part of the long groove 6, which flat part is orthogonally crossed with the direction of the axial center of the through-hole 2. The valve sleeve 19 thus structured is manufactured by the use of a cylindrical base material with a bottom. A punch 5, which is provided successively with plural projected lines 4 in the axial direction on the outer peripheral surface, is force-fitted into a recessed hole from the opening part of this base material with a bottom to form long grooves 6. In this case, a flat part 4a with a specific width crossing orthogonally in the direction of the axial center is preformed in the tip end of the projected line 4, and a flat part 6a is formed in the end of the long grooves 6. After that, the clogged bottom of this base material is cut off, the end of the opening is deformed inward to clog the opening of the long grooves 6, and a valve sleeve product is obtained through a finishing process.