Patent ID: 8397609

Claim:
A machining method in which both end portions of an elongated workpiece are supported horizontally by end portion supporting means and the middle portion of the workpiece is supported by middle portion supporting means, and the supported workpiece is rotated about its axis and is machined by a tool held by tool holding means, the machining method characterized in that: first, the workpiece is supported by the supporting means and a measuring head for measuring the distance between the measuring head and the outer peripheral surface of the workpiece without contact is attached to the tool holding means; subsequently, the workpiece is rotated about its axis at a rotational speed for when the workpiece is machined and the distance between the measuring head and the outer peripheral surface of the workpiece is measured by the measuring head, and the deflection amount of the workpiece at the portion thereof supported by the middle portion supporting means is calculated; thereafter, on the basis of the calculated deflection amount, the workpiece supporting position in the vertical direction of the middle portion supporting means is adjusted so that the height positions of both end portions of the workpiece being rotated and the height position of the middle portion thereof become the same; and then the workpiece is machined by the tool held by the tool holding means.