Simulation of Hobbing for Analysis of Cutting Edge Failure Due to Chip Crush

Abstract

There are great advantages in dry hobbing not only for friendliness on the environment, but also for increasing productivity and for decreasing manufacturing cost. Dry hobbing, however, often causes failures of cutting edge of hob or problems about the surface quality of tooth flank of manufactured gear, which have not been of problem in case of hobbing with cutting oil. Pinching and crushing of generated chips between cutting edge of hob and tooth flank of work gear is considered to be a major cause for those problems. In this report, a calculating method of trace of each cutting edge of hob relative to work gear is compiled to simulate the clearance between cutting edge of hob and tooth flank of work gear. The thickness and form of generated chip and its movement on rake surface of hob tooth during hobbing process can be clarified by consulting the result of this simulation. Probability of pinching of chips between cutting edges of hob and tooth flank can be evaluated by dealing with the relation among the position and width of clearance, chip thickness and direction of chip movement, which contributes to successful dry hobbing.