The main control object of the CNC system is the displacement of the coordinate axis (including moving speed, direction, position, etc.), and its control information mainly comes from CNC machining or movement control program. Therefore, as the most basic components of the numerical control system should include: the program's input / output device, numerical control device, servo drive these three parts.
Program input/output device. The function of the input/output device is to input and output data such as numerical control machining or motion control program, machining and control data, lathe parameters, coordinate axis position, and detection switch status. The keyboard and display are the most basic input/output devices necessary for any CNC device. In addition, depending on the CNC system, it can also be equipped with optoelectronic readers, tape drives or floppy disk drives. As a peripheral device, a computer is one of the commonly used input/output devices.
CNC device. The numerical control device is the core of the numerical control system. It consists of input/output interface lines, controllers, operators, and memory. The function of the numerical control device is to compile, calculate and process the data input by the input device through internal logic circuit or control software, and output various information and instructions to control various parts of the machine tool to perform prescribed actions. Among these control information and commands, the most basic are the feedrate, feed direction and feed displacement command of the coordinate axes. It is generated after the interpolation operation, and is supplied to the servo drive, which is amplified by the driver and finally controls the displacement of the coordinate axis. It directly determines the movement of the tool or axis.
Servo drive. The servo drive is usually composed of a servo amplifier (also called a driver, a servo unit) and an actuator. On CNC lathes, AC servo motors are currently used as actuators; linear motors have been used on advanced high-speed machining lathes. In addition, in the previously produced CNC lathes, there are also cases where a DC servo motor is used; for a simple CNC lathe, a stepping motor can also be used as an actuator. The formation of the servo amplifier depends on the actuator and it must be used in conjunction with the drive motor.
