Numerically controlled machine tool

A method for correcting a quadrantal protuberance to a workpiece formed using a numerically controlled machine tool having a numerical controller comprising the steps of:

• storing a plurality of sets of different quadrantal protuberance correction signals;
• selectively storing condition signals, said condition signals being one of a machine condition and a geometrical error correction signal;
• selecting between a first set of said correction signals to be used in combination with said condition signals and a second set of said correction signals to be used in an absence of said condition signals;
• and
• controlling a command signal correction means by means of a combination of said signals,
• wherein in case said numerical controller generates said condition signals, at least two of said sets of said different quadrantal protuberance correction signals are stored, and in case said numerical controller does not generate said condition signals, a first set of said correction signals used in combination with said condition signals and a second set of said correction signals are used,
• wherein said numerical controller includes a geometrical error correction setting means which selectively generates said condition signals.

A numerically controlled machine tool having a quadrantal protuberance correction storage means that stores a plurality of sets of the amount of quadrantal protuberance correction so as to correspond to various operating modes of the machine tool, the numerically controlled machine tool comprising:

• means (3) for inputting information concerning presence or absence of geometrical error correction wherein a signal concerning presence or absence of geometrical error correction is sent to a geometrical error correction setting means (300) and a quadrantal protuberance correction setting means (301), wherein the geometrical error correction setting means (300) sends a signal concerning the amount of geometrical error correction to a contouring control correction means (302) in case there is any geometrical error correction, and does not send a signal concerning the amount of geometrical error correction in case there is not any geometrical error correction, wherein the quadrantal protuberance correction setting means (301) sends a signal concerning the amount of first quadrantal protuberance correction to the contouring control correction means (302) in case there is any geometrical error correction, and the quadrantal protuberance correction setting means (301) sends a signal concerning the amount of second quadrantal protuberance correction to the contouring control correction means (302) in case there is not any geometrical error correction,
• first to third command signal correction means (203, 204, 205) controlled by the contouring control correction means (302), wherein in case there is any geometrical error correction, the first to third command signal correction means (203, 204, 205) correct X-axis servo command signals, Y-axis servo command signals and Z-axis servo command signals, respectively, on the basis of the amount of geometrical error correction, and correct them on the basis of the amount of first quadrantal protuberance correction, whereby geometrical errors are corrected, and quadrantal protuberances are corrected if there is any geometrical error correction, but if there is not any geometrical error correction, the first to third command signal correction means (203, 204, 205) correct the X-axis servo command signals, the Y-axis servo command signals and the Z-axis servo command signals, respectively, on the basis of the amount of second quadrantal protuberance correction, so that the quadrantal protuberances are corrected in case there is not any geometrical error correction.