Method and apparatus for machining a non-circular workpiece

A method for machining a non-circular workpiece with a machine tool having a tool movable in a feed direction perpendicular to the rotational axis of the workpiece, wherein said tool is moved back and forth against the workpiece in a synchronous relationship with rotation of the workpiece, said method comprising steps of:

• inputting profile data composed of plural of data prepared for plural angular positions of the workpiece, each of which comprises an angular position of the workpiece and a desired radius, command values indicating positional change of said tool being calculated base upon said profile data using a Fourier series;
• determining coefficients of the Fourier series using least square method in such a way that difference between a profile defined by the Fourier series and an ideal profile defined by the profile data becomes smaller than a predetermined allowable error;
• effecting a calculation using the Fourier series and coefficients determined at said determining step to obtain command values;
• and
• moving said tool in accordance with the obtained command values to machine the workpiece into the desired final shape.

An apparatus for machining a non-circular workpiece wherein a tool is moved back and forth against a workpiece in a synchronous relationship with rotation of the workpiece, said apparatus comprising:

• data input means for inputting profile data defining a desired final shape of the workpiece and being composed of plural data prepared for plural angular positions of the workpiece, each of which comprises an angular position of the workpiece and a desired radius;
• calculating means for calculating command values indicating positional change of said tool using a Fourier series;
• determining means for determining coefficients of the Fourier series using least square method in such a way that difference between a profile defined by the Fourier series and an ideal profile defined by the profile data becomes smaller than allowable errors which are given for the plural angular position and which are different from each other;
• control means for effecting calculation by said calculating means for using coefficients determined by said determining means to obtain command values;
• and
• drive means for moving said tool in accordance with the obtained command values to machine the workpiece into the desired final shape.

A method for machining a non-circular workpiece with a machine tool having a tool movable in a feed direction perpendicular to the rotational axis of the workpiece, wherein said tool is moved back and forth against the workpiece in a synchronous relationship with rotation of the workpiece in a synchronous relationship with rotation of the workpiece, said method comprising steps of:

• inputting profile data composed of plural data prepared for plural angular positions of the workpiece, each of which comprises an angular position of the workpiece and a desired radius, command values indicating positional change of said tool being calculated based upon said profile data using a Fourier series;
• determining coefficients of the Fourier series using least square method in such a way that difference between a profile defined by the Fourier series and an ideal profile defined by the profile data becomes smaller than allowable errors which are given for the plural angular positions and which are different from each other;
• effecting a calculation using the Fourier series and coefficients determined at said determining step to obtain command values;
• and
• moving said tool in accordance with the obtained command values to machine the workpiece into the desired final shape.