Abstract: With regard to the slot process of closed blisk, a 5-axis slot plunge milling method of closed blisk is studied. First, this article analyzes the machinability of blisk channel and proposes the channel region division method. Then, the algorithm to solve the best ruled generatrix of plunging milling channel boundary is presented based on the least area principle. The method is addressed to generate the ruled envelope surfaces in view of blade-offset-surfaces and internal and external ring-offset-surfaces, respectively. 5-axis plunge milling tool path of closed blisk is presented finally. The results show that the channel region division and the ruled envelope surface generating can be solved by this approach, and the slot plunge milling of closed blisk can be achieved effectively.

Key words: closed blisk, milling, boundary line, ruled envelope surface, tool path