| 摘要 |
PURPOSE:To enable a piston for a master cylinder to be manufactured with minimum material required, by forming a cylindrical surface which is coaxial with the engaging parts at each end of the prepiston piece, on the connecting part when machining both engaging parts of the prepiston piece formed by cold forging. CONSTITUTION:The projecting part 3 of a prepiston piece is held by a fixing chuck C1, while a chuck C2 is engaged in the push rod inserting hole 5 of a large diameter engaging part 4. Then the outer surfaces of the small diameter engaging part 2 and the large diameter engaging part 4 are machined as shown by the single dotted line of the diagram respectively. At the same time, the conical face 9 between the connecting part 8 and the large diameter engaging part 4 is also machined as indicated by the singly dotted line, and thus a cylindcrical surface 10 having the same axis as the large diameter and small diameter engaging parts 2, 4 is formed next to the large diameter engaging part 4. Then the both chucks are disengaged and a chuck C3 is used tohold the outside of the small diameter engaging part 2 and the cylindrical surface 10 so that a cap engaging groove 6 and push rod inserting hole 5 are machined simultaneously. Thus, as cool-forged material can be used, a piston can be manufactured with the minimum quantity of the material. |
