Method and apparatus for grinding non-circular workpiece

An apparatus for machining a workpiece into a non-circular configuration by rotating the workpiece fixedly mounted on a main spindle about the main spindle and causing a tool to engage the rotating workpiece in a direction perpendicular to the axis of the main spindle while controlling the forward and backward movement of the tool, said apparatus comprising:

• a) means for storing the shape of the workpiece as a group of points represented by polar coordinates about the axial center of the main spindle as an origin;
• b) means for storing the size of the tool;
• c) means for converting said group of points representing the shape of the workpiece into profile data representing the profile of the workpiece;
• d) means for preparing division point data dividing the profile data of the workpiece shape into line segments of minute and equal length;
• e) means for preparing reference X/C axes data representing the relationship between the position of the tool head and the rotational angle of the main spindle when the tool engages the workpiece at each of said division points;
• f) means for preparing temporary X/C axes data by selecting the division points in said reference X/C axes data at a given rate;
• g) means for calculating at least one of the velocity, acceleration and rate of acceleration change in each of the tool head and main spindle when the workpiece is machined in accordance with said temporary X/C axes data and for judging whether or not the calculated value exceeds a threshold;
• h) means for changing said rate of selecting if the calculated value exceeds the threshold;
• i) means for determining said temporary X/C axes data as modified X/C axes data when the calculated value does not exceed the threshold;
• and
• j) means for controlling the tool head and main spindle in accordance with said modified X/C axes data.