Machining apparatus and equipment of thin section long workpiece

A machining apparatus of a thin section long workpiece, comprising a workpiece clamp device for horizontally holding the thin section long workpiece having a constant section shape or having the same section shape in spaced positions in a longitudinal direction in two positions of the same section shape, wherein the workpiece clamp device is constituted of a driving clamp device and a driven clamp device having the same holding device, the driving clamp device rotates the thin section long workpiece centering on a horizontal axis O extending in the longitudinal direction of the thin section long workpiece, and the driven clamp device follows movement of the thin section long workpiece and idles centering on said horizontal axis, wherein the holding device comprises:

• a hollow ring supported so as to be rotatable centering on the horizontal axis O and which inner portion has a cylindrical shape;
• an intersecting flat member attached to an inner portion of the hollow ring and which has two flat portions extending in parallel with the horizontal axis and crossing at an angle relative to each other;
• and a holding head disposed in the hollow ring in a position opposite to the intersecting flat member, directly moved in a diametrical direction toward the intersecting flat member, and freely tilted centering on an axis parallel to the horizontal axis O.