Realization of multi-axis machining difficulties in multi-axis NC machining technology

People have long recognized the superiority and importance of multi-axis NC machining technology, but so far, the application of multi-axis NC machining technology is still limited to a few well-funded departments, and there are still unresolved problems. Because of the interference of machining space and the control of tool position, the NC programming, NC system and machine tool structure of multi-axis NC machining are much more complicated than those of three-axis machine tools. At present, the multi-axis NC machining technology has the following problems:

(1) Multi-axis NC programming is abstract and difficult to operate.

This is a headache for every traditional NC programmer. 3-axis machine tools only have linear coordinate axes, and 5-axis CNC machine tools have various structural forms; The same NC code can achieve the same machining effect on different 3-axis NC machine tools, but the NC code of a 5-axis machine tool cannot be applied to all types of 5-axis machine tools. In addition to linear motion, NC programming should also coordinate the calculation of rotary motion, such as rotation angle and stroke inspection, nonlinear error inspection, tool rotary motion calculation and so on. It deals with a lot of information and is very abstract. The operation of multi-axis NC machining is closely related to programming skills. If users add special functions to machine tools, programming and operation will be more complicated. Only through repeated practice can programmers and operators master the necessary knowledge and skills. The lack of experienced programmers and operators is a big obstacle to the popularization of multi-axis NC machining technology.

(2) It is difficult to compensate the cutter radius.

In the 5-axis NC program, the tool length compensation function is still valid, but the tool radius compensation is invalid. When using cylindrical milling cutter for contact forming milling, it is necessary to compile different programs for tools with different diameters. At present, the popular CNC system can't complete the tool radius compensation, because the ISO file doesn't provide enough data to recalculate the tool position. In the process of NC machining, users need to change tools frequently or adjust the precise dimensions of tools. According to the normal machining procedure, the tool path should be sent back to CAM system for recalculation, which leads to the inefficiency of the whole machining process. The final solution of this problem depends on a new generation of CNC control system, which can identify workpiece model files (such as STEP, etc. ) or CAD system files in common format.

(3) Buying machine tools requires a lot of investment.

There is a big price gap between multi-axis CNC machine tools and 3-axis CNC machine tools. In addition to the input of the machine tool itself, the CAD/CAM system software and post-processor must be upgraded to meet the requirements of multi-axis NC machining, and the calibration program must be upgraded to simulate the whole machine tool.