Patent ID: 6568233
Filing Date: 2003-05-27
Classification: B21D,B21F,B21J,B21K

Abstract:
A method for diametrically expanding a metal shaft, comprising the steps of:holding the shaft between a pair of holders spaced at a distance (D); rotating the work around its axis, moving one of the holders toward the other holder so as to compress the work; biasing one of the holders in a direction which crosses the axis of the other holder, so as to bend the work and build up bulged portions accruing inside the bent portion around the periphery of the work within the distance (D) until a desired expansion is achieved; and straightening up the work; wherein the compression is constantly applied to both the inner and outer sides of the work to be bent, and the rotation is initiated at the latest immediately after the bending is started, and the straightening-up is performed under the continued compression and rotation.