1, open-loop control machine tools
The so-called open-loop control machine tool refers to the control system without feedback, the system does not have a position feedback element, usually using a stepper motor as an actuator. Input data through the numerical control system, the command pulse, through the ring distributor and drive circuit, so that the stepper motor turns a step angle, and then through the transmission mechanism to drive the table to move a pulse equivalent distance. The moving speed and displacement of the moving parts are determined by the frequency of the input pulse and the number of pulses.
2, semi-closed-loop CNC machine tools
At the end of the drive motor or at the end of the drive screw installed angular displacement detection device, through the detection of the motor or screw angle indirectly measure the actual position or displacement of the actuating parts, and then feedback to the CNC system. Obtain higher accuracy than the open-loop system, but its displacement accuracy is lower than that of the closed-loop system, and it is easy to achieve system stability compared with the closed-loop system. Now most CNC machine tools are widely used in this semi-closed-loop feed servo system, the inertia of the machine tool moving parts are not included in the detection range.
3, closed-loop control of CNC machine tools.
Closed-loop control of CNC machine tools, the harness motor can be used DC or AC two servo motors, and need to have position feedback and speed feedback, in processing at any time to detect the actual displacement of moving parts, and timely feedback to the CNC system. It is compared with the command signal obtained by the interpolation operation, and the difference as a servo harness control signal, and then drive the displacement parts to eliminate displacement errors.
