Design of the detection system of CNC lathe thread machining

The most important function of the CNC lathe is threads machining. By studying the detection of photoelectric Encoder, a thread machining detection system was projected, and proposed specific methods to Pulse Shaping, frequency doubling, phase discrimination, and counting photoelectric encoder output signals. And this is to solve the problems of pulse counting and differentiating directions, controlling precision, synchronization and anti-interference when screw-cutting is on its way. Dual differential receptors SN75115 is introduced into the system as its plastic circuit, and to kick out common-mode interference at the same time. Frequency doubling circuit use the exclusive-or gate associate with flip-flop, and use flip-flop 74LS74D to accomplish phase discrimination and synchronous control. Practice shows that the system has its reality effect to materialize signal detecting with high accuracy and stability as well as position-servo control.