In order to meet the requirements of CNC machine tools for tools that are durable, stable, easy to adjust, and changeable, in recent years, machine-clampable indexable tools have been widely used, reaching 30% to 40% of the entire CNC tool in number, metal removal The amount accounts for 80% to 90% of the total.
2. Features of CNC tools
Compared with the tools used on ordinary machine tools, CNC tools have many different requirements, mainly including the following features:
Good rigidity (especially roughing tools), high precision, anti-vibration and small thermal deformation;
Good interchangeability, easy to change the knife quickly;
High life, stable and reliable cutting performance;
The size of the tool is easy to adjust to reduce the tool change time;
The tool should be able to reliably break chips or crumbs to facilitate the removal of chips;
Serialization and standardization for programming and tool management.
Second, the choice of CNC machining tools
The selection of the tool is carried out in the human-computer interaction state of the NC programming. The tool and tool holder should be selected correctly according to the machining capacity of the machine tool, the performance of the workpiece material, the machining process, the amount of cutting and other relevant factors. The general principle of tool selection is: easy installation and adjustment, good rigidity, durability and high precision. Under the premise of meeting the processing requirements, try to choose a shorter tool holder to improve the rigidity of the tool processing.
When selecting a tool, the size of the tool should be adapted to the surface size of the workpiece being machined. In the production, the peripheral contour of the plane parts is often processed by an end mill; when milling the plane, the cemented carbide insert milling cutter should be selected; when the bosses and grooves are machined, the high-speed steel end mill is selected; the surface of the blank is machined or roughed. For the hole, the corn milling cutter with the carbide insert can be selected; for the machining of some three-dimensional and variable bevel contours, ball-end milling cutters, ring milling cutters, conical milling cutters and disc milling cutters are often used.
In the free-form surface (mold) processing, since the cutting speed of the end of the ball-end tool is zero, in order to ensure the machining accuracy, the cutting distance is generally the tip-tight distance, so the ball head is often used for the finishing of the surface. The flat-blade tool is superior to the ball-end knives in terms of surface quality and cutting efficiency. Therefore, the flat-blade knives should be preferred if the surface is roughed or finished under the premise of ensuring no cutting. In addition, the durability and accuracy of the tool are highly dependent on the tool price. It must be noted that in most cases, the choice of a good tool increases the tool cost, but the resulting processing quality and processing efficiency increase. , can make the entire processing cost greatly reduced.
In the machining center, various tools are mounted on the tool magazine, and the tool selection and tool change operations are performed at any time according to the program. Therefore, a standard tool holder must be used in order to quickly and accurately load the standard tool for drilling, boring, expanding, milling, etc. onto the machine tool spindle or tool magazine. The programmer should be aware of the structural dimensions, adjustment methods, and adjustment range of the tool holder used on the machine to determine the radial and axial dimensions of the tool during programming. At present, China's machining center adopts TSG tool system. Its tool holder has two types: straight handle (3 specifications) and taper shank (4 specifications), including 16 different handles.
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