Computer numerical control (CNC) machine tools are a type of typical mechatronics product. A detailed explanation is as follows:

### I. Definition and Core Characteristics

A CNC machine tool is an automated machine tool equipped with a program control system. This control system can logically process programs specified by control codes or other symbolic instructions, decode them, represent them with coded numbers, and input them into the CNC device via an information carrier. After computation and processing, the CNC device sends out various control signals to control the actions of the machine tool, automatically machining parts to the shape and size required by the drawings. The core characteristic of a CNC machine tool is "computer program control," which distinguishes it from the manual or mechanical control of traditional machine tools.

### II. Working Principle

The working principle of a CNC machine tool mainly includes the following steps:

1. **Program Creation**: Based on the drawings of the workpiece, perform process analysis and create the machining program. Methods for creating machining programs typically include manual programming and automatic programming, respectively for simple and complex workpiece machining.

2. **Program Input**: Input the machining program into the CNC device. The method of inputting the machining program varies depending on the input device of the CNC machine tool. There are two ways for the CNC device to read the program: one is to read and process simultaneously, which is an intermittent operation method; the other is to read the entire machining program into the internal memory of the CNC device and then call it from the memory during processing.

3. **Trajectory Interpolation Calculation**: With the support of the control software, the CNC device performs a series of processing and calculations on the input machining program, performing trajectory interpolation calculations. Trajectory interpolation is the process of densifying data points between the coordinates of the start and end points of a line segment, calculating the coordinates of a series of intermediate points, and outputting pulse signals to the corresponding coordinates.

4. **Servo System Control and Machine Tool Machining**: The CNC device outputs interpolation pulse signals, which are converted and amplified, and through the servo motor and mechanical transmission mechanism, the machine tool's actuators drive the tool to perform machining, producing parts that meet the requirements of the drawings.

### III. Key Technologies and Structure

The key technologies supporting CNC machine tools include CNC systems, servo systems, precision mechanical structures, and sensing technologies, which together ensure high-precision and high-efficiency machining. CNC machine tools are mainly composed of the following parts:

1. **CNC Device**: This is the "brain" of the CNC machine tool, responsible for receiving, parsing, and executing machining programs and issuing control signals.

2. **Servo Mechanism**: Used to achieve feed servo control and spindle servo control of the CNC machine tool, driving the movement of the machine tool's various axes.

3. **Machine Tool Body**: Includes the base, column, worktable, and other basic components, as well as tools, fixtures, and other auxiliary components.

4. **Auxiliary Devices**: These are necessary supporting components of CNC machine tools used to ensure the operation of the CNC machine tool, such as cooling, chip removal, lubrication, lighting, and monitoring. This includes hydraulic and pneumatic devices, chip removal devices, interchangeable worktables, CNC turntables and indexing heads, as well as tools and monitoring and detection devices.

### IV. Characteristics and Advantages

CNC machine tools have the following characteristics and advantages:

1. **Strong Adaptability**: Strong adaptability to the workpiece, suitable for the characteristics of single-piece production of products such as molds, providing a suitable machining method for mold manufacturing.

2. **High Machining Accuracy**: Machining accuracy generally reaches 0.05~0.1mm, with high positioning accuracy and stable machining quality.

3. **Multi-Coordinate Linkage**: Can perform multi-coordinate linkage, capable of machining parts with complex shapes.

4. **High Production Efficiency**: Can effectively reduce workpiece machining time and auxiliary time, improving productivity.

5. **High Degree of Automation**: Can reduce labor intensity and is conducive to the modernization of production management.

### V. Development History

The development history of CNC machine tools has gone through several stages, from the initial CNC devices with electron tube components, to CNC devices with transistor components and printed circuit boards, to integrated circuit CNC devices, direct CNC systems and computer CNC systems, and finally to today's microcomputer CNC devices. The functions of CNC machine tools have continuously expanded, their size has continuously shrunk, their prices have gradually decreased, and their reliability has been greatly improved.

In summary, CNC machine tools are highly efficient, precise, and automated machining equipment widely used in various mechanical manufacturing industries.