This kind of machine tool does not have the position detection feedback device and usually uses the stepping motor as the actuator. The input data is processed by the numerical control system, and the pulse command is sent out to make the stepping motor turn a step angle, and then it is transformed into the straight-line movement of the workbench by the mechanical transmission mechanism. The moving speed and displacement of the moving parts are determined by the frequency and number of the input pulses.
The end of the motor or the end of the lead screw is equipped with a detection element, which indirectly detects the displacement of the moving part by detecting its rotation angle, and then feeds back to the CNC system. Because most of the mechanical transmission links are not included in the closed-loop system, the stable control characteristics can be obtained. Although its control accuracy is not as good as the closed-loop control CNC centre lathe, the debugging is more convenient, so it is widely used.
This kind of CNC machine tool is equipped with position detection feedback device. The position detection feedback device adopts linear displacement detection element, which is directly installed on the moving parts of the machine tool. The measurement results are directly fed back to the NC device. Through the feedback, the transmission error in the whole mechanical transmission chain from the motor to the moving parts of the machine tool can be eliminated, and the precise positioning can be achieved finally.