Acceleration/deceleration control apparatus

A acceleration/deceleration control apparatus for controlling movement of a cutting tool, having an actual velocity, of a numerically controlled machine tool along first and second axes using command data arranged in blocks, said apparatus comprising:

• decoder means for receiving he command data and for decoding the blocks of the command data into a command velocity and a command position;
• decision means for determining interpolated position data based upon the command position;
• distribution means for generating first and second distributed pulses corresponding to the first and second axes based on the interpolated data and the command velocity;
• comparison means for comparing the command velocity with the actual velocity;
• and
• delay means for delaying the generating of the first and second distribution pulses by said distribution means until the actual velocity corresponding to a current block of command data decelerates to an amount less than the command velocity of a next block of command data.

A method for eliminating deviation in machining trajectory f a machine tool, having an actual velocity, controlled by a numerical control unit using a machining program, having m command data blocks, where m is an integer, each command data block including a position command and a velocity command, said method comprising the steps of:

• (a) inputting the (n-1).sup.th command data block from the machining program where (1.ltoreq.n.ltoreq.m);
• (b) executing the (n-1).sup.th command data block by issuing pulse distribution pulses to the machine tool in order to control movement of the machine tool;
• (c) inputting the n.sup.th command data block from the machining program during said executing step (b);
• (d) determining if the magnitude of the n.sup.th command velocity in the n.sup.th command data block is less than the (n-1).sup.th command velocity in the (n-1).sup.th command data block;
• (e) delaying execution of the (n-1).sup.th command data block until the actual velocity is less than the (n-1).sup.th command velocity if said determining in step (d) is affirmative;
• and
• (f) executing the (n-1).sup.th command data block.