Compact Design of High-Contact-Ratio Spur Gears

This study presents a computer simulation for the dynamic design of compact high-contact-ratio spur gear transmissions. High contact ratio gears have the potential to produce lower dynamic tooth loads and minimum root stress but they can be sensitive to tooth profile errors. The analysis presented in this work was performed by using the NASA gear dynamics code DANST (Dynamic Analysis of Spur Gear Transmissions). In the analysis, the addendum ratio (addendum/diametral pitch) was varied over the range 1.30 to 1.40 to obtain a contact ratio of 2.00 or higher. The constraints of bending stress limit and involute interference provide the main criteria for this investigation. Compact design of high-contact-ratio gears with different gear ratios and pressure angles was investigated. Comparison of compact design between low-contact-ratio and high-contact-ratio gears was conducted. With the same operating parameters, high-contact-ratio gears appear to have much more compact design than low-contact-ratio gears. For compact design of high-contact-ratio gears, a diametral pitch of 6.00 appears to be the best choice for an optimal gear set.

Research on Efficiency and Load Sharing Characteristics of High-Speed-Ratio Planetary Gear Transmissions

Wolfrom planetary gear (WPG), James Ferguson planetary gear (JFPG) and plus-planetary gear (PPG), feature high speed ratios and a low number of gears, but their efficiency is low and their performance is sensitive to manufacturing errors. In this paper, low-loss gears are used to improve the efficiency of these high-speed-ratio planetary gear transmissions. The methods to achieve the low-loss gears are optimizing modification coefficients and addendum coefficients simultaneously in order to equalize approach-contact ratio and recess-contact ratio. Besides, the sensitivity of the load sharing performance to manufacturing errors is analyzed in the view of load sharing characteristics. A load sharing model, which includes position errors of planet bearings and tooth profile errors of planets, is built up to obtain the load sharing characteristics of WPG, JFPG and PPG. Load sharing performance of WPG, JFPG and PPG with manufacturing errors are analyzed. And effects of load sharing measures are compared.

On-Machine Measurement of Tooth Profile Errors of Spiral Bevel Gears and its Simulation

Precise measurement of tooth profile errors is the key technology for realizing close-loop manufacturing of spiral bevel gears. The measuring principle of tooth profile errors and the processing method of measuring datum is the key technology for realizing precise measuring. Based on the generating principle of spiral bevel gears and the model of CNC machine tool, the on-machine measuring principle and the measuring datum processing method were established. In order to verify the correctness of on-machine measuring principle, the on-machine measuring simulation system was established based on AutoCAD development platform. According to the spatial coordinates and normal vector of the discrete points of theoretical tooth profile, the on-machine measurement of tooth profile errors was simulated by intersection Boolean operation and the values of errors were calculated. The correctness of simulation algorithm is validated by comparing simulation result with the practical measuring result.

Research on Meshing Theory and Simulation of Noninvolute Beveloid Gears with Crossed Axes

Crossed axes noninvolute beveloid gears meshing with line contact has been studied in this paper. The engagement equation and tooth profile equation have been presented by applying the theory of gearing. Meanwhile the tooth profile errors and axial errors have been calculated by means of numerical analysis and provided a theoretical way to calculate the induced normal curvature along the normal direction of the contact line in this paper.