Numerical control method

A numerical control method for controlling a lathe including a plurality of machine tools having a plurality of turrets, said method comprising the steps of:

• supplying data items indicative of cutting conditions for respective tools mounted on the turrets, a machining program, and material conditions of a workpiece to be cut by the machine tools, said cutting conditions including a desired final depth of cut along the workpiece and an incremental depth of cut to be achieved during a given cutting operation;
• computing a machining capacity required to cut the workpiece based on said cutting conditions, machining program, and material conditions, said computing step being computed in accordance with at least one of an allowable overall power and an allowable overall torque of all of said tools together;
• determining whether said machining capacity is outside a range of one of said allowable overall power and said allowable overall torque;
• issuing an output to correct the cutting conditions by varying said incremental depth of cut by the tools with respect to the workpiece when the value of the machining capacity is outside at least one of the allowable overall torque range and the allowable overall power range to correct the machining capacity required to cut the workpiece into the allowable operating parameter range of the machine tools, said varying of incremental depth of cut in turn increasing the number of cutting operations required along the workpiece to achieve said final depth of cut;
• and
• issuing the reduced cutting conditions to the machine tools.