Kohei Saiki

Profile Shifted Conical Involute Gear With Deep Tooth Depth

This paper proposes a new design method for profile shifted conical gear with deep tooth depth. This method has two new concepts. First, this method is based on the designed pitch point where the rack shift coefficient is not zero. Second, this method is based on the theory of nonintersecting bevel gear such as hypoid gear, to decide the mounting dimensions of the profile shifted conical involute gears with deep tooth depth. The profile shifted conical involute gears have the designed pitch point that is not the standard pitch point. Limits of the rack shift coefficient and the facewidth, for the undercut and the zero top land, are clarified. Next, the production system is shown, and several typical test gears are manufactured. Paths of contact between tooth surfaces of profile shifted conical gears are obtained by tooth bearing tests. As a result, the measured value of limits of the rack shift coefficient and the facewidth on the manufactured tested gears are in good agreement with the theoretical ones. Moreover, test results of tooth bearing are in good agreement with the theoretical ones.Copyright

Loaded TCA of Measured Tooth Flanks for Lapped Hypoid Gears

Usually, the Loaded Tooth Contact Analysis (i.e. LTCA) of hypoid gears uses the nominal tooth flanks described by the machine setting and the cutter specifications. Only a few studies are performed on the LTCA directly using the measured tooth flanks such as carbonize-hardened and lapped hypoid gears. This paper presents an innovative LTCA method directly using the measured tooth flanks at each manufacturing step including not only the milling or hobbing process but also the troublesome heat-treatment, lapping or grinding processes. The proposed new LTCA method is extremely concise. Firstly, the 3-D shape data of the manufactured tooth flanks, which are the original x-y-z coordinates but not the differences against their nominal tooth flanks as before, are obtained on a coordinate-measuring machine. Another important factors the load deflections are measured on the assembled transmission by applying the static transmitting torque. Secondly, the pinion and gear are localized at the nominal mounting position, and the no load TCA can be obtained by calculating the gap between the original tooth flanks at each roll angle. Lastly, since the load deflections can be considered as the movement of mounting position, the Loaded TCA can be obtained by calculating the gap between the moved tooth flanks at new mounting position. As practical applications, the new LTCA method is used to improve the strength of high-torque hypoid gears for an All-Wheel-Drive transmission. As a result, the tooth contact pattern and pitting position observed in endurance test agreed well to the LTCA predictions and the demanding life is achieved by modifying the loaded contact pattern of lapped hypoid gears.Copyright

Experimental Research on the Vibration and Noise Behavior of Helical Gearing System

Going with interior noise reduction in a vehicle, gear noise that is of pure frequency has been becoming a great influence on the comfortable driving. For decreasing the gear noise, it is important to predict precisely the gear noise behavior at the design stage before manufacturing. Therefore, it is necessary to clarify the physical mechanism of each resonance noise peak by actual measurement in the wide condition range of rotation speed and transmitting torque. In this research, a new 85kw oil-cooled motoring apparatus (Max speed: 6000rpm/135Nm, Max torque 400Nm/2000rpm) is developed for measuring the 3-dimensional (transverse, axial, rotational, and tilting) vibration of rotating gear blank. Also, the 3-directional (X, Y, and Z) vibration of the bearing’s holder, and the radiated gear noise are measured at the same time. As the result, the relationship between exciting vibration of rotating gear blank and the responding vibration of the bearing’s holder is carried out. The different effect upon the radiated gear noise of various vibration resonance modes is also investigated. Especially, some new interesting vibration modes, such as the drive and driven gears vibrate individually or synchronously, are found. Lastly, the mechanism of several resonance peaks which frequently causing the gear noise problems from slow city driving to fast highway operation, is conjectured concisely.Copyright