Electrical discharge machine and method for manufacturing machined object using the same

A method for manufacturing a machined object, comprising:

• (i) a step of providing a workpiece for the machined object with respect to an electrical discharge machine for applying a voltage between an electrode and the workpiece to generate electrical discharge such that the workpiece is melted by the electrical discharge and machined, the electrical discharge machine comprising:
• an electrode holder that holds the electrode;
• an ultrasonic motor that has a fingertip that comes into contact with the electrode holder, and moves the electrode holder in a predetermined driving direction by moving the fingertip in an annular manner at an ultrasonic-range frequency;
• a roller bearing that guides the movement of the electrode holder in the driving direction, the roller bearing comprising:
• movement blocks that are fixed to the electrode holder;
• a rail that supports the movement blocks and guides movement of the movement blocks;
• and
• a plurality of roller elements that are interposed between the movement blocks and the rail;
• and
• a control circuit that controls a position of the electrode in the driving direction by driving the ultrasonic motor, the control circuit being configured to move the electrode holder based on an abnormality occurring in resistance against the movement of the electrode holder in the driving direction, the electrode holder being moved by a movement distance equivalent to when a largest roller element among the plurality of roller elements rolls and rotates once or longer without sliding;
• and
• (ii) a step of machining the workpiece using the electrical discharge machine.