Chuck soft jaw, chuck soft jaw making method, workpiece machining method, and hybrid machine tool

A workpiece machining method comprising:

• attaching a chuck soft jaw to a chuck main body of a first workpiece holder rotatably around a center axis together with the chuck main body so that the chuck soft jaw is movable in a first direction away from the center axis and in a second direction toward the center axis, the chuck soft jaw having a second holding surface and a first holding surface having a hardness higher than a hardness of the second holding surface;
• holding an oxidized surface of a first portion of the workpiece by the first holding surface of the chuck soft jaw;
• cutting the oxidized surface of the workpiece to form a machined surface while the oxidized surface of the workpiece is held by the first holding surface of the chuck soft jaw;
• holding the machined surface of the workpiece by the second holding surface of the chuck soft jaw;
• and
• machining a second portion of the workpiece while the machined surface of the workpiece is held by the second holding surface of the chuck soft jaw.

A hybrid machine tool comprising:

• a plurality of processing units configured to make a chuck soft jaw from a raw material block attached to a chuck main body, the chuck soft jaw including a first holding surface configured to hold an oxidized surface of a workpiece and a second holding surface configured to hold a machined surface of the workpiece;
• a first workpiece holder configured to hold the workpiece via the chuck soft jaw;
• control circuitry configured to control the plurality of processing units and the first workpiece holder;
• the first workpiece holder comprising:
• the chuck main body configured to support the chuck soft jaw having the first holding surface and the second holding surface;
• a first drive unit configured to move the chuck soft jaw in a first direction away from a center axis of the chuck main body and in a second direction toward the center axis;
• and
• a rotary drive unit configured to rotate the chuck main body about the center axis;
• and
• the plurality of processing units comprising:
• a first processing unit configured to form the second holding surface on the raw material block by cutting the raw material block attached to the chuck main body;
• and
• a second processing unit configured to form the first holding surface having a hardness higher than a hardness of the second holding surface on the raw material block by processing the raw material block attached to the chuck main body.