| Summary: | 碩士 === 國立中正大學 === 機械工程所 === 98 === In mechanical industry, the main stiffness and the transmission efficiency in machine tool are very important for manufacturing performance. In general, the transmission system of machine tool can be classified to two parts, the first part is the geared system in headstock and the second part is the lead screw between castings. Therefore, the influence of the geared system of machine tool can’t be neglected for manufacturing performance.
In geared system research, the effect of designed parameters on dynamic behavior, such as pressure angle and number of tooth, performed popularly in the past. However, the influence of modification coefficient on dynamic behavior still hasn’t any discussion in depth. Besides, many scholars are usually used the Fourier series to simulate the mesh stiffness, so that the error exists between practical experience and mathematical technique always.
In this study, the gear profile with modification coefficient using rack cutter is proposed, and the mesh stiffness at the position on the line of action is calculated. Besides, the nonlinear dynamic behavior with different modification coefficient is analyzed by applying the time-varying stiffness. From the numerical results, the influence of negative modification coefficient on system stability is bigger then the positive modification coefficient for the case where center distance can be changed. Moreover, the positive modification coefficient will be increased the chaotic region when system is run in high speed, and the negative modification coefficient will be decreased the chaotic region of system. For the case where center distance is fixed, the contact ratio and maximum mesh stiffness in a gear pair will be decreased together when the modification coefficient is increasing. Besides, because the variation of maximum mesh stiffness is bigger then the contact ratio, so that the dynamic response of system will be reduced.
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