Different types of CNC lathes have different requirements for sensors. Generally speaking, large-scale machine tools require high speed response, and medium and high-precision CNC machine tools mainly require precision.
At present, the sensors of CNC lathes mainly include pulse encoders, linear gratings, rotary transformers, induction synchronizers and other categories:
1. Linear grating sensor
Linear grating sensor is made by the phenomenon of light transmission and reflection. It is commonly used in displacement measurement, with higher resolution, higher measurement accuracy than photoelectric encoder, and is suitable for dynamic measurement. In the feed drive, the grating ruler is fixed on the body of the CNC lathe, and the pulse signal generated in it directly reflects the actual position of the carriage. The servo system that uses grating to detect the position of the working table of the CNC lathe is a fully closed-loop control system.
2. Pulse encoder
Pulse encoder is an angular displacement (rotation speed) sensor, which can turn mechanical rotation angle into electric pulse. Pulse encoders can be divided into three types: photoelectric, contact, and electromagnetic. Among them, there are many photoelectric applications.
Resolver is an induction micromotor whose output voltage and angular displacement are in a continuous function relationship. The resolver consists of a stator and a rotor. Specifically, it consists of a core, two stator windings, and two rotor windings. The primary and secondary windings are placed on the stator and rotor, respectively. The electromagnetic between the primary and secondary windings The degree of coupling depends on the rotation angle of the rotor.
4. Induction synchronizer
Induction synchronizers are made using the principle that the mutual inductance of two planar windings varies with position. The function is to convert the angle or linear displacement into the phase or amplitude of the induced electromotive force, and it can be used as a sensor to measure the linear or angular displacement. The induction synchronizer can be divided into linear type and rotary type according to its structure. The linear induction synchronizer is composed of fixed length and sliding scale. The fixed length is installed on the CNC lathe bed. The sliding scale is installed on the moving parts and moves with the worktable. The stator of the rotary induction synchronizer is a fixed disc. The rotor is a rotating disc. The induction synchronizer has the advantages of high precision and resolution, strong anti-interference ability, long service life, simple maintenance, long-distance displacement measurement, good manufacturability and low cost. Linear induction synchronizers are now widely used in static and dynamic measurement of large displacements, such as coordinate measuring machines, program-controlled CNC machine tools, high-precision heavy-duty machine tools and machining center measurement devices. Rotary induction synchronizers are also widely used in CNC lathes and turntables of instruments and various rotary servo control systems.