BORING CONTROL METHOD

A boring control method for a machine tool for automatically boring a deep hole using a central control means (20) performing boring with programmed control. In the boring, the number of processing and steps of the machine tool is kept minimum, load torque of a tool (1) is detected continuously using torque detection means, and the movement of the tip portion of the tool (1) desired for a piece of work is confirmed from a reference point (R) to a hole bottom using a Z-axis movement device (6). The boring is continued in each step until the load torque exceeds a predetermined torque limit value, performed in a condition where a main shaft rotation number, or rotation speed of the tool (1), and feed speed form a specific pattern, and a condition is set where a total step number (f) does not exceed a predetermined limit step number (N).