Numerical control feed device for machine tool

A numerical control feed device for moving a slide with one of a tool and a workpiece to a position designated by numerical control data in a machine tool, said feed device comprising:

• a servomotor for moving said slide;
• a drive amplifier for driving said servomotor;
• a first detector for detecting the actual feed amount of said slide;
• a second detector for detecting the actual feed rate of said slide so as to generate a feedback velocity signal;
• feed command means for generating feed command signals in accordance with said numerical control data, said feed command signals representing an objective feed amount to which said slide is to be moved and an objective feed rate at which said slide is to be moved;
• error signal generating means responsive to said feed command signals given from said feed command means and the actual feed amount detected by said first detector, for generating an objective velocity signal corresponding to the difference between said feed command signals and said actual feed amount;
• a feedforward velocity signal generator responsive to said feed command signals for generating a feedforward velocity signal corresponding to said objective feed rate;
• a gain adjustable amplifier for amplifying said feedforward velocity signal from said feedforward velocity signal generator at an amplifying ratio designated thereto so as to output an amplified feedforward velocity signal;
• a subtraction circuit for generating a difference signal based on said objective velocity signal, said feedback velocity signal and said amplified feedforward velocity signal, so as to output said difference signal to said drive amplifier;
• and
• amplifying ratio command means for generating said amplifying ratio based on various parameters so as to output said amplifying ratio to said gain adjustable amplifier.