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 machining, since the cutting speed of the end of the ball-end tool is zero, in order to ensure the machining accuracy, the cutting line spacing is generally very dense, 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 mount the standard tool for drilling, boring, expanding, milling, etc. on 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 kinds of handles: straight handle (three specifications) and taper shank (four specifications), including 16 different handles.

In the economical NC machining, since the sharpening, measuring and replacing of the tool are mostly manual and manual, the occupation time is long. Therefore, the order of the tools must be arranged reasonably. Generally, the following principles should be followed: 1 Minimize the number of tools; 2 After a tool is clamped, all the machining parts that can be carried out should be completed; 3 The rough-finished tools should be used separately, even for tools of the same size; 4 First milling and drilling; 5 first surface finishing, then 2D contour finishing; 6 When possible, the automatic tool change function of CNC machine tools should be used as much as possible to improve production efficiency.

Semi-finishing and finishing; Third, the amount of NC machining <br> <br> determine a reasonable choice of cutting parameters principle is that when roughing, mainly to increase productivity in general, but should also consider the economic and processing costs Under the premise of ensuring the processing quality, the cutting efficiency, economy and processing cost should be taken into account. The specific values ​​should be based on the machine manual, the cutting amount manual, and the experience.

Previous page