抄録
A large improvement in gear cutting productivity is needed to reduce CO_2 emissions. A substantial improvement in productivity can be expected for face-hobbed hypoid gears by changing from the conventional wet cutting process to a high-speed dry cutting process. To facilitate the switch to a dry cutting method, changes are needed in materials, tools, cutting conditions, and cutting machines. Highly accurate synchronization between the cutter axis and the work axis and a system for high-speed dry cutting are necessary for the cutting machines. However, conventional face milling machines do not have such a synchronizing system. The aim of this study is to achieve high-speed dry cutting of face-hobbed hypoid gears on conventional face milling machines. A prototype of a hypoid cutting machine using the face milling method and equipped with a synchronizing system was developed. This machine is able to cut face-hobbed hypoid gears at high speed in a dry cutting process. Concretely, the rotary encoder arrangement, spindle stiffness and the machine's drivetrain system were optimized. Machining accuracy was improved by adopting measures based on an analysis of vibration from intermittent cutting and the drivetrain. Management of heat generated by dry cutting was optimized and a chip evacuation device was added. With these measures, the target machining accuracy and tool life were achieved after conducting several cutting trials. As a result, cutting conditions were found that facilitate high-speed dry cutting of face-hobbed hypoid gears.
