Control device for NC machine tool - has a computer controlling speed, acceleration and braking of drives for machine tool feed axes

摘要

A computer derives from input signals at specified control intervals nominal values for position control circuits. These control circuits in turn produce nominal values for speed control circuits of drives allocated to the machine tool feed axes. The computer (2) comprises a computing unit (9) and a process rate control logic unit (10). The computing unit (9) calculates for each control interval discrete acceleration values, discrete speed values and travelled distance increments from input signals for acceleration, nominal speed and total distance travelled. The process rate control logic unit (10) generates a brake command for a whole control interval, depending on the acceleration, speed and remaining travel. This time interval is the one into which the exact starting point for braking falls. The braking process is so controlled until a switching off threshold speed is reached, that in at least one control interval the braking command is switched off and the operation carried out at constant speed, provided the ideal braking parabola is not exceeded.