Three-dimensional cutter compensation system

A three-dimensional cutter compensation system for machining a workpiece in response to a machining program, comprising:

• a cutter which is movable about X, Y, and Z axes and is tiltable about a B axis, said cutter having a predetermined radius;
• a memory which stores the present position of the X, Y, Z, and B axes of the cutter and the cutter radius;
• cutter direction vector calculating means which calculates a cutter direction vector from the present position of the X, Y, Z, and B axes of the cutter stored in said memory;
• programmed path calculating means which calculates a programmed path for said cutter in response to said machining program;
• and
• cutter compensation vector calculating means which calculates a cutter compensation vector in response to the cutter direction vector received from said cutter direction vector calculating means, the cutter radius received from said memory, and the programmed path received from said programmed path calculating means.

A method for three-dimensional cutter compensation which numerically controls a tiltable cutter of predetermined radius in three-dimensional space in response to a machining program, comprising the steps of:

• reading positional information corresponding to a plurality of cutter control axes for controlling tilt of the tiltable cutter from memory;
• calculating a cutter direction vector from said plurality of cutter control axes;
• calculating a cutter motion vector corresponding to a direction of travel of the cutter in response to the machining program;
• reading a radius of the cutter and a radius of an arc of an edge of the cutter from memory;
• calculating a cutter compensation vector from the cutter direction vector, the cutter motion vector, the cutter radius read from memory, and the radius of the arc of the edge of the cutter read from memory.