DETECTOR FOR POSITIONAL ERROR OF NUMERICAL CONTROL MACHINE TOOL

摘要

PURPOSE:To increase the resolution in an economical way, by increasing the accuracy up to the n-fold value in terms of an electronic circuit. CONSTITUTION:An incremental shaft encoder 12 produces channel signals CHA, CHB and CHZ of phases (a), (b) and (z) respectively. The signals CHA and CHB have a difference of phase of 90 deg. to each other and can disriminate the rotating direction of a motor 11. The signal CHZ means a 1-rotation signal which is produced with each rotation of the encoder 12. A counting part 15 is set at zero by the clear signal CL to be the original point of the position data. An n-fold accuracy counter 16 receives an input by the channel signal, and a 2-bit data is formed at the counter 16 to obtain the n-fold accuracy. An error detecting part 17 detects no error when a count-zero signal (g) is produced at the part 15 at the moment when the signal CHZ is applied, and then applies the error signal ERROR to the computer side of an NC device when no CHZ nor (g) is applied.