Abstract
The article proposes a new method of calculation of the indicators of the durability of the gear transmission of heavy-loaded roadheading machines, allowing a more accurate assessment of the dynamic loading of the teeth. Within the framework of this technique, the elastic moment amplification factors determined by the amplitude-frequency characteristic of transmission are used instead of the specific circumferential dynamic force in the calculation of the maximum operating voltages. The maximum stresses in the bending of teeth and the probability of failure-free operation of the technical system are determined. A spur transmission used in the drive of the Executive body of roadheader is considered as an example of application of the proposed design technique. The comparison of calculated estimations of gear transmission reliability obtained on the basis of the standard method and using amplitude-frequency characteristics is carried out. In the considered design example durability of transfer for a step cycle of loading is more than 2 times higher in comparison with a continuous cycle of loading. It is shown that using a standard calculated coefficient that takes into account dynamic load, the calculated estimations of the durability of the transmission are significantly overestimated. At the same time, the error of the standard method will depend on the frequency range at which the transmission operates, and this error is most significant when the transmission operates near its own frequencies.
Highlights
The article proposes a new method of calculation of the indicators of the durability of the gear transmission of heavy-loaded roadheading machines, allowing a more accurate assessment of the dynamic loading of the teeth
Within the framework of this technique, the elastic moment amplification factors determined by the amplitude-frequency characteristic of transmission are used instead of the specific circumferential dynamic force in the calculation of the maximum operating voltages
A spur transmission used in the drive of the Executive body of roadheader is considered as an example of application of the proposed design technique
Summary
Если определенная по формуле (13) удельная динамическая сила превысит значение wFvmax, то при расчетах принимается wFv = wFvmax. Предел выносливости s–1д для шестерни связан с величиной s–1, определяемой по кривой усталости соотношением s -1д. Экспериментально определенные значения коэффициентов вариации действующих напряжений и предела выносливости шестерни, необходимые для вычисления среднего квадратичного отклонения логарифма долговечности (3), составляют соответственно us = 0,13 и u–1д = 0,08. 1 представлены значения коэффициентов, необходимых для вычисления амплитудных значений действующих напряжений и предела выносливости шестерни. Коэффициенты для вычисления максимальных действующих напряжений и предела выносливости шестерни. При этом изменение крутящего момента, а следовательно, и амплитуды напряжения обусловлено изменением частоты вращения. Для обоих режимов зададим одинаковое значение максимального крутящего момента MFmax = 6000 Н ⋅ м. Для каждого из режимов рассмотрим два способа изменения частоты и, соответственно, напряжения. Циклограмма для первого способа изменения частоты определяется данными табл.
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