CNC machine tools are usually composed of information carriers, input and output devices, numerical control systems, strong electric control devices, servo drive systems, position feedback devices, and machine tools.

1. information carrier
The CNC machine tool runs according to the given part processing program, and records all kinds of information necessary for processing the part in the part processing program, including the geometric information of the part processing, process parameters (feed rate, spindle speed, etc.) and auxiliary movements, etc. . The part processing program is stored on the information carrier with a certain format and code, and the information is input into the numerical control system through the input device. Commonly used information carriers are punched tapes, magnetic tapes, and magnetic disks. The CNC machine tool can also use the buttons and keyboard on the operation panel to directly input the processing information, or input the processing program written on the computer to the CNC system through the serial port.
Advanced CNC systems may also include an automatic programming machine or a CAD/CAM system.

2. I/O device
The function of the input device is to read the CNC machining information in the information carrier into the internal memory of the CNC system. According to different information carriers, there are different input devices. In the early days, photoelectric readers were used to read punched tapes. Later, tape drives and floppy disk drives were widely used. Using MDI mode, use the input key on the control panel of the numerical control device to directly input the part processing program into the internal memory of the numerical control system. The NC machining program generated by the CAD/CAM system is input into the NC system by means of direct communication, or the NC machining program is input remotely using the DNC system input interface.
The function of the output device is to provide the operator with necessary information, such as program code, cutting amount, tool position, various fault information and operation prompts. Commonly used output devices include displays and printers, which can display or print output information. The high-end CNC system can also display the output information in a graphical way.

3. CNC system
The CNC system is the core of automatic machining of CNC machine tools, which is composed of hardware and software. Modern CNC systems generally use general-purpose computers as their main hardware parts, including CPU, memory, system bus, and input and output interfaces. The software part is mainly the main control system software, and its control methods are data operation processing control (machine tool motion stroke control) and sequential logic control (machine tool motion switch control). The interpolation operation module in the main controller is based on reading The imported part processing program, after decoding, compiling and other information processing, carries out the corresponding trajectory interpolation operation, and controls the movement of each coordinate axis of the machine tool by comparing it with the position and speed feedback signals of each coordinate servo system. The sequential logic control is mainly completed by the programmable controller PLC, which coordinates according to the requirements of each action in the machining process of the machine tool, and makes logical judgments according to each detection signal, thereby controlling the machine tool to work in an orderly and orderly manner.

4. Strong electricity control device
The main functions of the strong electric control device are to receive the spindle speed change, reversal, start or stop, tool selection and replacement, indexing table indexing and locking, workpiece clamping or unclamping, cutting Auxiliary operation signals such as opening or closing of the liquid directly drive the corresponding executive elements through power amplification to complete the automatic operation of CNC machining.

5. Servo drive system
The servo drive system is the electrical transmission link between the CNC system and the machine tool. It receives the position control information from the CNC system and converts it into the feed movement and precise positioning movement of the corresponding coordinate axis. It is the last control link of the CNC machine tool. Therefore, its servo accuracy and dynamic response properties will directly affect the CNC machine tool productivity. , machining accuracy and surface machining quality. The servo drive system includes two units: spindle servo and feed servo. The spindle servo unit receives the steering and rotational speed commands from the PLC, and drives the spindle motor to rotate after power amplification. The feed servo unit receives the displacement command of the numerical control system in each interpolation cycle, drives the feed motor to rotate after power amplification, and completes the speed control and feedback control functions at the same time. The executive devices of the servo drive system include power stepper motors, DC servo motors and AC servo motors.

6. position feedback device
The position feedback device measures the angular displacement of the servo motor or the linear displacement of the CNC machine tool table through the sensor, and converts it into a signal and transmits it to the CNC system. error generated.

7. machine tool
Machine tool refers to the mechanical structure of CNC machine tools. In order to adapt to the characteristics of CNC machining, CNC machine tools have great changes from ordinary machine tools in terms of overall layout, appearance, main drive system, feed drive system, tool system and operating mechanism. The main features are:
① Adopt high-efficiency and high-performance transmission components, such as rolling screw pair, linear rolling guide rail pair, etc., the transmission chain is short, the structure is simple, and the transmission precision is high;
②The machine tool has high precision, static rigidity, dynamic rigidity and thermal rigidity, which can meet the requirements of large allowance cutting and precision machining cutting;
③There is a perfect tool automatic exchange and management system. After the workpiece is clamped once, multiple processing procedures can be completed;
④It has the measures to eliminate the transmission gap of the transmission pair, which ensures the transmission accuracy and dynamic performance of the transmission mechanism;
⑤ The fully enclosed outer shell with sliding door structure ensures the safety of processing operations.

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