What parts does the CNC system consist of? What is the role of each?

Author: MULAN - Plastic Molding Manufacturer

The CNC system is the core of all CNC equipment. 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 the CNC machining or motion control program. Therefore, the Z basic composition of the numerical control system should include: the input/output device of the program, the numerical control device, and the servo drive.

1. Input/output device The function of the input/output device is to input and output data such as CNC machining or motion control program, processing and control data, machine tool parameters, coordinate axis position, and detection switch status. The keyboard and display are the most basic input/output devices necessary for any numerical control equipment. In addition, depending on the numerical control system, it can also be equipped with a photoelectric reader, tape drive or floppy disk drive, etc.

As a peripheral device, a computer is one of the most commonly used input/output devices. 2. Numerical control device The numerical control device is the core of the numerical control system. It is composed of input/output interface circuit, controller, arithmetic unit and memory.

The function of the numerical control device is to compile, calculate and process the data input by the input device through the internal logic circuit or control software, and output various information and instructions to control the various parts of the machine tool to perform specified actions. Among these control information and commands, Z is basically the feed speed, feed direction and feed displacement command of the coordinate axis. It is generated after interpolation operation, provided to the servo drive, amplified by the drive, and finally controls the displacement of the coordinate axis to meet the requirements of cnc processing.

It directly determines the moving track of the tool or coordinate axis. In addition, depending on the system and equipment, such as: on the CNC machine tool, there may also be spindle speed, steering, start and stop commands; tool selection and exchange commands: cooling and lubrication device start and stop commands; workpiece loosening Opening and clamping commands; auxiliary commands such as indexing of the workbench. In the basic numerical control system, they are provided to the external auxiliary control device in the form of signals through the interface, and the auxiliary control device performs the necessary compilation and logical operation on the above signals, and drives the corresponding executive device after amplification to drive the mechanical components of the machine tool. , hydraulic pneumatic and other auxiliary devices to complete the action specified in the instruction.

3. Servo drive The servo drive is usually composed of a servo amplifier (also known as a drive, servo unit) and an actuator. On CNC machine tools, AC servo motors are generally used as actuators at present; on advanced high-speed processing machine tools, linear motors have begun to be used. In addition, DC servo motors were also used on CNC machine tools produced before the 1980s; for simple CNC machine tools, stepping motors can also be used as executive devices.

The form of the servo amplifier depends on the execution device, and it must be used in conjunction with the drive motor. The above are the most basic components of the CNC system. With the development of numerical control technology and the improvement of the performance level of machine tools, the functional requirements of the system are also increasing. In order to meet the control requirements of different machine tools, ensure the integrity and unity of the numerical control system, and facilitate the use of users, commonly used and relatively advanced CNC systems generally have internal programmable controllers as auxiliary control devices for machine tools.

In addition, on the metal cutting machine tool, the spindle drive device can also become a part of the numerical control system; on the closed-loop numerical control machine tool, the measurement and detection device is also indispensable to the numerical control system. For advanced numerical control systems, sometimes computers are even used as the system's human-machine interface and data management, input/output equipment, so that the numerical control system has stronger functions and better performance. In short, the composition of the numerical control system depends on the performance of the control system and the specific control requirements of the equipment. In addition to some, there may be more controls.