振動ホブ切り加工法の開発

抄録

Dry hobbing, which is a gear processing method without cutting oils, is useful for cutting cost and reducing environmental pollution. However, the dry hobbing has problems, for example, increase of the cutting temperature, cutting surface damage by the chips, and so on. This study proposes a new dry hobbing method "vibration hobbing" for the purpose of reducing the cutting temperature mainly. The method gives axial micro vibration to a rotating hob by a vibration generator. This paper explains the structure of the vibration hobbing machine which we developed, and shows the effectiveness of the machine by experimental results. We carried out the vibration hobbing as finish machining on the following conditions : the cutting depth is 0.34 mm, the hob frequency is 740 Hz, the hob amplitude is about 2μm, the cutting speed is 40.8m/min, the hob feed is 1.0mm/rev, the module is 1.75, and work hardness is HRC50. As the result, the black chips were changed into the white chips by the vibration. This result shows that the vibration hobbing reduces the cutting temperature. Moreover, when the work hardness is HRC55 and the hob amplitude is 1.2 μm, the height of feed marks on the gear tooth surface are reduced by the vibration hobbing. Thus, the effect of vibration hobbing is reducing the cutting temperature and the height of feed marks on the gear tooth surface for high hardness materials.