Hob Cutting Simulation for Analysis of Chip Crush between Cutting Edge of Hob and Tooth Flank of Gear

Abstract

There are great advantages in dry hobbing not only for friendliness on the environment, but also for increasing processing speed, 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 is considered to be a major cause for those problems. In this report, a simulation method of trace of each cutting edge of hob relative to gear blank is developed. This simulation makes it possible to calculate the clearance between cutting edge of hob and tooth flank of gear blank. The thickness and form of generated chip and its movement on rake surface of hob tooth can be clarified. This achieves easy understanding of those values during bobbing process. Probability of pinching of chips between cutting edges of hob and tooth flank can be evaluated by position and width of clearance, chip thickness and direction of chip movement, which contributes to successful dry hobbing.