The tool selection of metal parts processing is one of the important contents in the numerical control processing technology. It not only affects the efficiency of CNC machining, but also directly affects the processing quality of parts. Because the spindle speed and range of CNC machine tools are much higher than that of ordinary machine tools, and the spindle output power is relatively large, compared with the traditional processing methods, higher requirements are put forward for CNC machining tools, including high precision, high strength and rigidity. Good, high durability, and requires dimensional stability, easy installation and adjustment, the characteristics of CNC drive spindle drive system. This requires a reasonable tool structure, standardization of geometric parameters, and serialization. CNC tooling is one of the prerequisites for improving the machining efficiency. Its choice depends on the geometry of the part being machined, the state of the material, the fixture and the rigidity of the tool selected by the machine tool. The following should be considered:

 

(1) Select the tool according to the cutting performance of the part material. Such as car or milling high-strength steel, titanium alloy, stainless steel parts, it is recommended to choose a good wear-resistant indexable carbide cutting tools.

 

(2) Select the tool according to the processing stage of hardware parts. That is to say, the roughing stage is mainly based on removing the margin, and the tool with better rigidity and lower precision should be selected. The semi-finishing and finishing stages are mainly used to ensure the machining accuracy and product quality of the part, and high durability and accuracy should be selected. For high cutting tools, the accuracy of the tools used in the roughing stage is the lowest, and the accuracy of the tools used in the finishing stage is the highest. If the same tool is used for rough and finish machining, it is recommended to use the tools that are eliminated from the finishing process when the rough machining is performed. The wear of the tools that are eliminated during the finish machining is mostly due to the slight wear of the blades, the wear of the coating is lighted, and the continued use will affect the finish machining. Processing quality, but less impact on roughing.

 

(3) Select the tool and geometric parameters according to the characteristics of the CNC lathe machining area. When the part structure allows, a tool with a large diameter and a small aspect ratio should be selected; the center-end angle of the over-center milling cutter for cutting thin-walled and ultra-thin-wall parts should have enough tangential angle to reduce the cutting of the tool and the cutting part. force. When processing aluminum, copper and other softer material parts, choose an end mill with a slightly larger front rake and do not use more than 4 teeth.

 

When selecting a tool, the dimensions of the tool must be adapted to the surface dimensions of the workpiece being machined. In production, the peripheral contours of plane parts are often machined with end mills; when milling planes, hard alloy insert cutters are selected; when machining bosses or grooves, high speed steel end mills are selected; When machining holes, corn milling inserts with carbide inserts can be selected; for the machining of some three-dimensional profiles and variable bevel profiles, ball-end cutters, ring cutters, taper cutters and disk cutters are often used. .

 

When performing free-form surface machining, since the cutting speed of the end of the ball-end cutting tool is zero, in order to ensure the precision of the numerical control machining, the cutting line spacing is generally very small, so the ball-end milling cutter is suitable for surface finishing. The end mill is far superior to the ball end mill both in terms of surface machining quality and machining efficiency. Therefore, in the premise of ensuring that the part is not over-cut, the rough end and semi-finishing work surface should be selected as much as possible. Milling cutter. In addition, the tool's durability and precision are highly related to the tool's price. It must be noticed that, in most cases, selecting a good tool increases the tool cost, but the resulting increase in machining quality and machining efficiency. , you can greatly reduce the cost of the entire process.

 

In the machining center, all the tools are pre-installed in the magazine, and the corresponding tool change actions are performed through the NC program's tool selection and tool change commands. The corresponding standard tool holders suitable for the machine tool system specifications must be selected so that the tools for CNC machining can be quickly and accurately mounted on the machine tool spindle or returned to the tool magazine. The programmer should be able to understand the structure of the shank used in the machine tool, adjust the method and adjust the scope of the content, to ensure that the radial and axial dimensions of the tool is determined when programming, and arrange the order of the tool.