The Principle and Introduction of CNC Machine Center

With the development of science and technology, the society's requirements for product diversification are becoming stronger and stronger, and the cycle of product replacement is required to be shorter and shorter, so that the proportion of multi-variety and small-batch production has increased significantly. At the same time, with the aerospace , Shipbuilding, military industry, automobile, agricultural machinery and other industries have continuously improved product performance requirements, and there are more and more parts with complex shapes in the products, and the processing quality requirements have also been continuously improved. It is difficult to adapt to this diversification by using traditional ordinary processing equipment. , high-efficiency and high-quality requirements for flexibility and complex shape parts. In order to solve the above problems. A high-precision, high-efficiency "flexible" automated production equipment - CNC machine came into being.

1. Composition of CNC machine

CNC machine are typical mechatronic products, which are high-efficiency, high-precision, high-flexibility and high-automation modern machining equipment that integrates modern machinery manufacturing technology, automatic control technology, detection technology, and computer information technology. Like other mechatronics products, it also consists of a mechanical body, a power source, an electronic control unit, a detection sensing part and an execution machine. Servo system, composition.

①Mechanical body

It is the body of the CNC machine and is the mechanical part used for various cutting processes.

②Power source

The part that provides power for CNC machine mainly uses electric energy.

③Electronic control unit

Its core is computer numerical control, referred to as CNC device, which decodes, calculates and logically processes various digital information received, generates various instruction information and outputs it to the servo system, so that the machine tool can be processed according to the specified operation. This part also includes corresponding peripherals, such as monitors, printers, etc.

④ Detection and sensing part

It mainly detects the linear displacement of the worktable and the angular displacement of the rotary worktable. The detection results are sent to the computer, or used in the position display or used for feedback control.

⑤Actuator, servo system

It is used to drive the shifting parts on the machine tool to make corresponding movements and control its positioning accuracy. For example, the tool movement of many CNC machine tools is completed by using the servo motor to drive the ball screw.

2. Classification of CNC machine

① Classification according to the technological use of CNC machine

General CNC machine tools. It is a variety of CNC machine tools that are similar in process feasibility to ordinary machine tools. The types are the same as ordinary machine tools, (such as CNC lathes, CNC milling machines, CNC grinding machines, CNC drilling machines, etc.)

The machining center is a CNC machine tool with a reverse library and an automatic tool changer.

Special CNC machine tools are special processing machine tools equipped with CNC devices (such as CNC wire cutting machine tools, CNC laser processing machine tools, etc.)

②. Classified according to the movement trajectory of CNC machine

(1) Point-to-point control of CNC machine tools. Its numerical control device only controls the moving parts of the machine tool from one position point to another position point, but does not control the motion trajectory between points. The tool does not perform cutting processing during the movement. (such as CNC drilling machine, CNC punching machine, etc.)

(2) Linear control CNC machine tools. In addition to controlling the exact position of the starting point and end point of the machine tool's moving parts, its numerical control device also controls the moving parts to perform linear cutting in a direction parallel to the machine tool coordinate axis or at an angle of 450 to the machine tool coordinate axis at an appropriate speed. (such as simple CNC lathe, simple CNC grinder, etc.)

(3) Contour controlled CNC machine tools. Its numerical control device can carry out linkage control on two or more coordinates at the same time, so as to realize the processing of curved contours and curved surfaces. (such as CNC milling machines, CNC lathes, etc.)

③. Classified by servo system control mode

(1) Open-loop control system.

(2) Semi-closed-loop control system.

(3) Closed-loop control system.

④. Classified by the number of coordinate axes controlled

(1) Two-coordinate CNC machine refers to a machine tool that can control the linkage of two coordinate axes at the same time and can process curved contour parts, (such as CNC lathe)

(2) Three-coordinate CNC machine refers to a three-axis CNC machine tool whose coordinate axes can be linked and controlled, and can be used to process less complex spatial surfaces, (such as three-coordinate CNC milling machine)

(3) Two half-coordinate CNC machine tools, (such as economical CNC milling machines)

(4) Multi-coordinate CNC machine tools, which have complex machine structure, high control precision, and complex processing procedures, are mainly used for processing parts with complex shapes (such as non-coordinate CNC milling machines)

3. Processing characteristics of CNC machine

① Strong applicability to parts processing

Different parts can be processed by changing the processing program, especially suitable for the current characteristics of various varieties, small batches, and fast product updates.

② High degree of automation

Under normal circumstances, in addition to loading and unloading workpieces. Most of the other processing processes are automatically completed by machine tools, which greatly reduces the labor intensity of workers.

③Processing quality is stable

During the processing, the machine tool works under the specified control instructions from the beginning to the end, which eliminates the influence of the operator's technical level and emotional changes on the processing quality, so the processing quality is stable and the dimensional consistency of a batch of parts is good.

④ High productivity

The range of spindle speed and feed rate of CNC machine tools is large, which allows the machine tool to perform powerful cutting for large cuts. Also on the machining center. Due to the use of the tool magazine. It can realize continuous processing of multiple processes on one machine tool, which greatly reduces the processing time and auxiliary time of parts, so the productivity is high.

⑤ Conducive to the modernization of production management

CNC machine tools use digital signals and standard codes as control information, which is easy to realize the standardization of processing information. At present, it has been organically combined with computer-aided design and manufacturing CNC/CAM, which is the basis of modern integrated manufacturing technology.

5. The basic working principle of CNC machine

In the processing of parts on ordinary machine tools, the operator constantly changes the relative motion trajectory between the tool and the workpiece according to the requirements of the part drawing, and the required parts are processed due to the cutting of the tool. And when machining parts on CNC machine tools. It is the processing sequence of the parts to be processed, the process parameters and the movement requirements of the machine tool to compile the processing program in the CNC language, and then input it to the CNC device. After the CNC device performs a series of processing on the processing program, it sends an execution command to the servo system. The servo system The system drives the movement of the moving parts of the machine tool to automatically complete the processing of the parts.