The main motion of CNC machine is rotation motion of main spindle via chuck or apex drives work piece, is used to transmission and speed governing via motor drives gearbox. During machining process, usually there is a requirement for a different rotation speed of main spindle, operation staff controls separation and integration of clutch via multiple positions of handle combination, gets multiple combination of gear to obtain multiple speeds, operation is inconvenience and maintenance is large, practices show that the fault rate of electromagnetic clutch using to adjust speed is high. The old feature of main spindle drive can not meet the requirement which the fast developing economy asks for CNC machine. Currently, more and more inverters match with CNC machine to control main spindles.
The whole electrical system is consist of CNC machine, inverter, time relay and brake assembly.
AC power supply connects to R, S, T terminals via breaker. The output terminals U, V, W connect with main spindle motor with right consequence. When the running command is inconsistent with the motor rotation direction, you can change any two phase of U, V, W or exchange control circuit terminal FWD/REV
Frequency given command is given by CNV with 0~10V or -10V~10V form, connects from AI1 and GND. The rotation direction and running control of motor is decided by the status of DI;
When DI1 and COM are connected, DI1 is high level, the motor runs forward. When DI2 and COM are connected, DI2 is high level, the motor runs reverse. When DI1 and DI2 do not connect with COM, both DI1 and DI2 are low level, the motor stops. The connection or disconnection of DI1 and COM & DI2 and COM is controlled by two relay contacts, the two contacts can be controlled by main spindle runs forward and main spindle runs reverse commands given by the numerical control system. Meanwhile, two digital output terminals are separately set as: TIA and TIC (function setting: running output), T2A and T2C (function setting: fault output).