Patent ID: 8014893

Claim:
A method of machining a workpiece with an offset tool, in which a groove (Da) extending in a Y-axis direction with a fixed cross-section containing a wave-shaped outline is formed by finish machining a roughly machined workpiece (D) having a predetermined machining allowance for the groove (Da) with an offset tool (T) that has a cross-section with a shape offset in a reducing direction by only a predetermined offset amount (o) relative to the wave shape and that rotates around an axis of rotation parallel to a Z axis perpendicular to the Y axis, the method comprising: a feeding step in which the offset tool (T) is moved relative to the workpiece (D) within an X-Z plane perpendicular to the Y axis only by the offset amount (o) in a given direction from an initial position, a first cutting step in which the machining allowance is cut along the entire length of the groove (Da) while moving the offset tool (T) relative to the workpiece (D) in the Y-axis direction, an incising step in which the offset tool (T) is moved relative to the workpiece (D) within the X-Z plane only by a predetermined distance on the circumference of a circle having the initial position as the center thereof and the offset amount (o) as a radius thereof, and a second cutting step in which the machining allowance is cut along the entire length of the groove (Da) while moving the offset tool (T) relative to the workpiece (D) in the Y-axis direction, wherein the incising step and the second cutting step are repeated a plurality of times.