Types and selection of commonly used cutting tools in CNC machining centers

1. Types and characteristics of cutting tools commonly used in digital animal processing

CNC machining tools must adapt to the characteristics of high speed, high efficiency and high degree of automation of CNC machine tools. Generally, they should include general tools, universal connection tool holders and a small number of special tool holders. The tool handle is to be connected to the tool and installed on the power head of the machine tool, so it has been gradually standardized and serialized.

1.1 There are many ways to classify CNC tools
a. According to the structure of the tool, it can be divided into
1) integral type;
2) embedded type, which is connected by welding or machine clip type, and the machine clip type can be divided into non-reversible and indexable; 3) Special types, such as composite knives, shock-absorbing knives, etc.

b. According to the materials used in the manufacture of tools can be divided into:
1) high-speed steel tools;
2) carbide tools;
3) diamond tools;
4) other material tools, such as cubic nitriding Boron cutting tools, ceramic cutting tools, etc.

c. From the cutting process, it can be divided into:
1) Turning tools, including outer circle, inner hole, thread, cutting tools, etc.;
2) Drilling tools, including drills, reamers, taps, etc.; BR> 3) Boring tools;
4) Milling tools, etc.

In order to meet the requirements of CNC machine tools for tool durability, stability, easy adjustment, and changeability, machine-clip indexable tools have been widely used in recent years, reaching 30% to 40% of the entire CNC tool in quantity , The amount of metal removal accounts for 80% to 90% of the total.

1.2 Compared with the tools used in ordinary machine tools, CNC tools have many different requirements, mainly with the following characteristics:

1) Good rigidity (especially for rough machining tools), high precision, small vibration resistance and thermal deformation; good interchangeability, easy to change tools quickly;
2) Long life, stable and reliable cutting performance;
3) The size of the tool is easy to adjust to reduce the time of tool change adjustment;
4) The tool should be able to reliably break or roll chips to facilitate the removal of chips;
5) Serialization and standardization to facilitate programming and tool management.

2. Selection of CNC machining tools

The selection of the tool is carried out in the state of human-computer interaction of NC programming. The tool and tool holder should be correctly selected according to the processing capacity of the machine tool, the performance of the workpiece material, the cutting amount of the processing process, and other related factors. The general principle of tool selection is: easy installation and adjustment, good rigidity, high durability and precision. Under the premise of meeting the processing requirements, try to choose a shorter tool holder to improve the rigidity of tool processing.
1) When selecting a tool, the size of the tool should be adapted to the surface size of the workpiece to be processed. In production, end mills are often used to process the peripheral contours of plane parts; when milling planes, carbide insert milling cutters should be selected, and high-speed steel end mills should be selected when machining bosses and grooves; When processing the rough surface or rough machining holes, you can choose the corn milling cutter with cemented carbide blades; Knives and disc milling cutters.

2) When processing free-form surfaces (moulds), since the cutting speed of the end of the ball head tool is zero, in order to ensure the machining accuracy, the cutting line spacing generally adopts the top-end close distance, so the ball head is often used for precision machining of curved surfaces. processing. The flat-end cutter is superior to the ball-end cutter in terms of surface processing quality and cutting efficiency. Therefore, as long as the non-cutting is guaranteed, the flat-end cutter should be preferred for rough machining or finishing of curved surfaces. In addition, the durability and precision of the tool have a great relationship with the price of the tool. It must be noted that in most cases, although the choice of a good tool increases the cost of the tool, the resulting improvement in processing quality and processing efficiency , the overall processing cost can be greatly reduced.

3) On the machining center, various tools are respectively installed on the tool magazine, and the tool selection and tool pressing actions are performed at any time according to the program. Therefore, standard tool holders must be used so that standard tools used in drilling, boring, expanding, milling and other processes can be quickly and accurately installed on the machine tool spindle or tool magazine. Programmers should understand the structural size, adjustment method and adjustment range of the tool holder used on the machine tool, so as to determine the radial and axial dimensions of the tool when programming. At present, my country’s machining centers use the TSG tool system, and its handles are divided into two types: straight handles (3 specifications) and tapered handles (4 specifications), including 16 types of handles for different purposes.

4) During the processing of economical CNC machine tools, since the sharpening, measurement and replacement of tools are mostly carried out manually, it takes a long time to assist, so the order of the tools must be arranged reasonably. Generally, the following principles should be followed: ①Reduce the number of tools as much as possible; ②After a tool is clamped, all the processing steps it can perform should be completed; the tools for rough and fine machining should be used separately, even if they are of the same size and specification; Drilling after milling; ⑤ Surface finishing first, followed by two-dimensional contour finishing; ⑥ Whenever possible, the automatic tool change function of CNC machine tools should be used as much as possible to improve production efficiency.

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