The selection of cutting tools and the determination of cutting parameters in CNC machining are completed in the state of human-computer interaction, which is in sharp contrast with ordinary machine tool machining. At the same time, programmers are required to master the basic principles of tool selection and cutting parameter determination, fully consider the characteristics of CNC machining in programming, and be able to select tools correctly. Tools and cutting parameters. CNC tools must adapt to the characteristics of high speed, high efficiency and high automation of CNC machine tools. Generally, it should include general tools, universal connection tool holders and a small number of special tool holders. The tool holder is connected with the tool and installed on the power head of the machine tool, gradually realizing standardization and serialization. There are many ways to classify CNC tools.
1. CNC machine tool structure
2. Inlaid type, using welding or clamping connection, can be divided into two types: non-transposition and transposition.
three. Special types, such as composite tools, shock-absorbing tools, etc.
Tool manufacturing materials
1. High-speed steel tools;
2. Tungsten carbide tools;
three. Diamond tool
4. Cutting tools of other materials, such as cubic boron nitride cutting tools, ceramic cutting tools, etc.
Cutting technology classification
1. Turning tools, including cylinders, inner holes, threads, tools, etc.
2. Drilling tools, including drill bits, reamers, taps, etc.
3. Boring tool
4. Milling cutter etc.
4. In order to meet the requirements of CNC machine tools for tool durability, stability, adjustability and replaceability, in recent years, machine tool clamping indexing tools have been widely used, reaching 30%-40% of the total number of CNC tools, and the total metal removal 80%-90% of the amount.
1. Good rigidity (especially for rough machining tools), high precision, anti-vibration, and small thermal deformation;
2. Good interchangeability, convenient and quick tool change.
3. Long service life, stable and reliable cutting performance;
4. Tool size is easy to adjust, reducing tool change adjustment time.
5. The cutter should be able to reliably break the chips or chips to facilitate the removal of chips.
6. Serialization and standardization to facilitate programming and tool management.
5. Choice of tools
The tool selection in CNC programming is carried out in the state of human-computer interaction. According to the relevant factors such as the machining capacity of the machine tool, the properties of the workpiece material, the processing procedure, and the cutting parameters, the correct tool and tool holder are selected. The general principles of tool selection are: easy installation and adjustment, good rigidity, durability and high precision. On the premise of meeting the processing requirements, a shorter tool holder should be used as much as possible to improve the rigidity of tool processing.
When selecting a tool, the size of the tool should match the surface size of the workpiece to be processed. In production, end milling cutters are often used to machine the peripheral contours of plane parts; carbide blade milling cutters should be used when milling plane parts; high-speed steel end milling cutters should be used when processing convex and grooves; corn milling cutters with carbide blades When processing rough surfaces or coarse holes, you can choose cemented carbide inserts; the corn milling cutter with cemented carbide inserts can process some solid surfaces and oblique contours. Tools commonly used in shape processing include ball end milling cutters, ring milling cutters, conical milling cutters and disc milling cutters.
In the free-form surface (mold) processing, since the cutting speed of the end of the ball nose tool is zero, in order to ensure the machining accuracy, the cutting distance is generally close to the top, so the ball nose is usually used for surface finishing. Flat-end tools are superior to ball-end tools in terms of surface quality and cutting efficiency. Therefore, as long as the surface is not cut, whether it is roughing or finishing, flat end milling cutters should be the first choice. In addition, tool durability and accuracy have a lot to do with the price of the tool. It must be pointed out that in most cases, although the selection of a good tool will increase the cost of the tool, the improvement of processing quality and efficiency will greatly reduce the overall processing cost.
In the machining center, various tools are installed on the tool library, and the tool selection and replacement actions are carried out at any time according to the program. Therefore, it is necessary to adopt a standard tool holder so that the standard tools used in the process of drilling, boring, expanding, and milling can be quickly and accurately installed on the machine tool spindle or tool magazine. The programmer should understand the structure size