| Gears are very impoint element for motion and power transmission in mechanicalsystems. The gear dynamics performance have great influence on entire transmissionsystem, with the increasing of performance such as fast, efficient, precise, reliable, lowvibration, low noise and lightweight. With the development of aerospace, machinery,electronics and ship industries, the performance of gear look forward to high-speed,overloaded. The study of dynamic characteristics was extensive concerned by theresearchers. Noise, vibration and dynamic characteristics of the gear are more seriousthan the performance of foreign. So transmission system, especially gear dynamiccharacteristics are an urgent engineering problem to be solved. But, most researchneglect the influence of tooth friction, with the further studies the researcher realize theimportance of tooth friction and can not be ignored in recent years. This paper focuseson the helical gear pair and analyzes the dynamics performance considering the toothfriction. The results have theoretical and practical significance for complex helical geardynamic performance, and also provide a theoretical basis for dynamic performance oftransmission system and technical support in order to reduce vibrations and noise.An improved numerical algorithm is proposed in order to calculate time-varyingcontact line according to gear meshing theory. The algorithm has broken through thecalculation restrictions of numerical from literature published abroad in recent years andexpands numerical calculation application range of the conference. The algorithm has somany advantages such as accurate, fast, convenient and practical. Analyze the changelaw of time-varying and reveal the minimum fluctuation conditions of the time-varyingcontact line. The results show the fluctuation of contact line is the smallest when thelength of L1(the smallest distance from the top of contact line to the right end surface)is a transverse pitch and L2(the smallest distance from the top of contact line to the leftend surface) equal L4(the shortest distance from the bottle of contact line to the rightend surface). The gear runs stably when the change law satisfies with the minimumfluctuation conditions. An algorithm is given about the calculation of tooth frictionforce and tooth friction torque condiering the friction coefficient of elastohydrodynamiclubrication. The change laws are obtained about tooth friction force and friction torque.The results shown that the fluctuation of time-varying contact line is very importantfactor for the fluctuation of tooth friction force and tooth torque. Within the selectedparameters scope of this article the fluctuation of tooth friction force and friction torqueare small when helix angle is20°. The conclusions will provide theoretical basis todesign gears and dynamic analysis of future work of this paper. The load distribution model of involute gear was constructed along thetime-varying contact line based on the energy minimization principle. The model wasused to calculate the load distribution along the contact line. The distribution rate is0.33~0.67when spur gear run at double contact zone. The load distribution of helicalgear is smoothly then spur gear. There is no load mutation of helical gear. The contactdeformation was calculated considering the tooth friction force. The analysis resultsshow the bending effect become larger with the increasing profile parameter. There is adeformation motion at pitch point, because the direction is changed of tooth frictionforce at pitch point. According to the above work the time-varying stiffness is calculatedand analyzed considering the tooth friction force. The calculation results providetheorial basis for frequency spectrum analysis and foundation for transmission error anddynamics analysis.The dynamic function of helical gear was built considering the tooth friction force.Main frequency resonance response,1/2order frequency resonance response and2orderfrequency resonance response were analyzed. The results show the tooth friction canreduce the resonance amplitude. The resonance amplitude will decrease with increasingof friction coefficient, but the resonance frequency will become large. The resonanceamplitude of static load obviously reduces when considering the tooth friction force. Thedynamic load and damping factor can reduce effectively the resonance amplitude, but theinfluence on resonance frequency is not obvious.In this paper, the integrate error and tooth friction are considered to constructdynamic equation of helical gear pair. The results about the maximum dynamictransmission error, maximum meshing force and maximum dynamic factor are obtainedwith the different speeds. The results show that error excitations are not important forheavy-duty gear. But, error excitations are important element for heavy-duty gear. Thedamping has obviously effect for reducing the dynamic response. Finally, the noise wasanalyzed considering different tooth base error、individual circular pitch error、pitchcumulative error and gear precision when the meshing impact was caused bytransmission error. |
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