Patent ID: 7283889

Claim:
A numerical control method that uses a numerical control device for a machine, the machine having at least three axes of linear motion, a first axis of rotation for rotating a tool head, and a second axis of rotation for rotating the tool head, the second axis of rotation being arranged above the first axis of rotation, said method comprising: obtaining a first actual tool length vector for which a tool length vector has been corrected, using a transformation matrix that is made from a reference position at which there is no mechanical error in the turning center of a spindle and an amount of misalignment of an actual turning center of the spindle from the reference position of the turning center of the spindle; rotating said first actual tool length vector by an amount in correspondence with an instruction for the second axis of rotation, by multiplying the first actual tool length vector by a transformation matrix that is made from a reference position at which there is no mechanical error in the second axis of rotation, an amount of misalignment of an actual second axis of rotation from the reference position, and an instruction position for the second axis of rotation, thereby obtaining a second actual tool length vector for which the misalignment of the second axis of rotation has been corrected; rotating said second actual tool length vector by an amount in correspondence with an instruction for the first axis of rotation, by multiplying the second actual tool length vector by a transformation matrix that is made from a reference position at which there is no mechanical error in the first axis of rotation, an amount of misalignment of the actual second axis of rotation and an actual first axis of rotation, an amount of misalignment of the actual first axis of rotation from the reference position of the first axis of rotations, and an instruction position for the first axis of rotation, thereby obtaining a third actual tool length vector for which the misalignment of the first axis of rotation has been corrected; adding an instruction position vector and workpiece origin offset vector to the third actual tool length vector to obtain a machine position; and driving the axes of linear motion and the first axis of rotation and the second axis of rotation to the machine position thus obtained.