| At present, the arithmetic of minimal orientation-distance which is gained by combining minimal orientation-distance principle with optimizing method of five points is a way for programming with section envelope principle in NC machining helical surface. Because it can solve constringency in alternate arithmetic, it can also avoid mass calculating for point-group, its speed of calculating is faster, and its principle is not complex. Now, it has become a very effective method for calculating cutter-trace to machine helical surface. However, interference checking to cutter-trace is not done in this method. In fact, in order to guarantee quality and improve precision, we must check interference. In this paper, the question of interference checking is studied with GA in machining helical surface.In this dissertation, firstly, we analyze the principle of section envelope. And with the principle of minimal orientation-distance, the question of cutter-interface checking is converted into global minimum between work piece and cutter in the final motion. So we can set up a model of interference checking. Secondly, the principle and the skill about GA are studied. For different cutting deepness in different place in helical surface, we get the minimum between work piece and cutter in the final motion with GA by three steps: confirming as region, orientating on macro, and searching on local. Then, a new method of interference checking is put forward. Finally, machining helical drilling-tool is used to prove its feasibility and validity.By using this method, the question of interference checking is effectively solved when machining helical surface with big plate milling cutter and section envelope principle. At same time, its fundamental is universal, so it can be employed to check cutter-interference in machining free form. If it is used in programming automatically on NC tools, we can get a CAM software module that can create cutter-trace without interference automatically.
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