| 摘要 |
<p>The cold forging process produces the spindle (1) for a bicycle pedal from a metal bar of uniform circular cross-section. The bar has axial holes (1f) in each end and the profile is obtained by a single forming operation. The forging has lengths (1e) of square section on each end formed by simultaneously converging matrices. The matrices have square section clearance recesses (9b) which are continued by tapering portion which form the shoulders (1b). After forging, the holes (1f) may be rebored and threaded to receive bolts securing the cranks. The spindle may then be completed by tempering followed by finishing the cylindrical bearing surfaces (1d). The forging machine may include a vice with two semi-circular jaws which grip the central zone of the bar (1). Two coaxial jacks (8) which locate at the opposite ends of the clamped bar (1), force inwards simultaneously the matrices.</p> |
