CNC milling machine

The CNC milling machine, also known as the Computer Numerical Control milling machine, is an automatic processing equipment developed on the basis of the general milling machine. The processing technology of the two is basically the same, and their structures are also similar. Generally speaking, CNC milling machines do not have automatic tool changing devices. CNC milling machines with tool magazines are often referred to as CNC machining centers.

According to the shape of the processed object, from simple to complex, it can be divided into two types: ordinary number milling machines and CNC milling machining centers. According to the difference in the number of control axes, they can be classified into three-axis CNC milling machines, four-axis CNC milling machines, and five-axis CNC milling machines. Among them, those with more than three axes are collectively referred to as multi-axis CNC milling machines. Considering the characteristics of processing technology, multi-axis CNC milling machines are generally suitable for processing parts with complex shapes. They need to complete multiple processes in one clamping and are often equipped with tool magazines for convenient automatic tool changing. Therefore, they are also called multi-axis CNC machining centers.

The CNC milling machine is mainly composed of mechanical body modules, which determine the performance of the machine tool, affect the processing function, and control the processing accuracy. A CNC milling machine is mainly composed of an electrical control system, a hydraulic cooling system and a mechanical system. Among them, the mechanical system supports various moving functional components, maintains the spatial position of each module structure, and keeps the dynamic and static accuracy of the machine tool. It is an important basic component of a CNC milling machine and generally includes the bed, column, spindle box, cross slide table and other auxiliary modules (such as bench vise fixtures, tailstock, etc.).

Unlike CNC lathes, the worktable of a CNC milling machine carries the blank and can achieve linear movement of two axes. A milling cutter installed on the spindle can achieve axial movement. Therefore, it is suitable for processing parts with three-dimensional spatial shapes and has a wider range of applications compared to CNC lathes. In addition, the increasingly advanced control system drives each feed axis, and even can achieve linkage. It can process complex parts with complex curved surfaces and freeform surfaces. Currently, it has been widely applied in important equipment manufacturing fields related to the national economy and people's livelihood, such as automobiles, molds, aerospace, etc.

CNC milling machine processing

The shape of the machined surface of a milling machine is generally composed of straight lines, arcs or other curves. The operator of a common milling machine follows the requirements of the drawing. By constantly changing the relative position between the tool and the workpiece and then coordinating it with the selected milling cutter speed, the tool can perform cutting operations on the workpiece, thus enabling the production of workpieces of various shapes.

CNC machine tool processing is to divide the motion coordinates of the tool and the workpiece into the smallest unit quantity, that is, the minimum displacement quantity. According to the requirements of the workpiece program, the numerical control system moves each coordinate by several minimum displacement amounts, thereby achieving the relative motion between the tool and the workpiece to complete the processing of the part.

In addition to the characteristics of ordinary milling machine processing, CNC milling processing also has the following features:

1. It has strong adaptability and good flexibility in parts processing, capable of processing parts with particularly complex contour shapes or difficult-to-control dimensions, such as mold parts and shell parts, etc.

2. It can process parts that are difficult or impossible to be processed by ordinary machine tools, such as complex curve parts described by mathematical models and three-dimensional curved surface parts.

3. It can process parts that require multiple processing procedures after being clamped and positioned once.

4. It features high processing accuracy and stable and reliable processing quality. The pulse equivalent of the numerical control device is generally 0.001mm, and for high-precision numerical control systems, it can reach 0.1μm. Additionally, numerical control processing also avoids operational errors by operators.

5. The degree of production automation is high, which can reduce the labor intensity of operators. It is conducive to the automation of production management.

6. High production efficiency: CNC milling machines generally do not require the use of dedicated fixtures or other specialized process equipment. When changing workpieces, it is only necessary to call up the processing program, clamping tools and adjust the tool data stored in the CNC device, thus significantly shortening the production cycle. Secondly, CNC milling machines have the functions of milling machines, boring machines and drilling machines, which highly concentrate the processes and greatly improve production efficiency. In addition, the spindle speed and feed rate of the CNC milling machine are both steplessly variable, which is conducive to choosing the optimal cutting parameters.

Milling cutter type selection: According to the geometric shape of the part to be processed, the types of tools to be selected include:

When processing curved surface parts, to ensure that the cutting edge of the tool is tangent to the processing contour at the cutting point and to avoid interference between the cutting edge and the workpiece contour, ball-end cutters are generally used. Two-edge milling cutters are used for rough machining, and four-edge milling cutters are used for semi-finish and finish machining.

2) When milling large planes: To enhance production efficiency and improve the surface roughness of the machined surface, insert type disc milling cutters are generally adopted.

3) When milling small planes or step surfaces, general-purpose milling cutters are generally used.

4) When milling keyways, to ensure the dimensional accuracy of the keyways, two-edge keyway milling cutters are generally used.

5) When performing hole processing, drill bits, boring tools and other hole processing tools can be used.