Numerical Calculation Of Adhesive Wear For Herringbone Gears Under Quasi-static And Dynamic Loads

Herringbone gears with the advantages of stable transmission,large bearing capacity and small axial force,are widely applied in the high speed reducer of the aviation gas turbine,the main propulsion drive system of large ship,and the main drive system of other large-scale equipment or complete equipment.However,adhesive wear has been one of the most prominent problems for heavy-loaded herringbone gears.Few researchers have studied on this project because of the complex tooth profile and operating conditions of herringbone gears.The numerical models of adhesive wear under quasi-static and dynamic loads for herringbone gears with clearance groove which are used in a certain kind of helicopter,are proposed.The main contents of this paper include:(1)Elaboration and analysis of wear mechanism and wear calculation model for gears.The wear process of gears is introduced,and the classification of gear wear mechanism is expounded comprehensively.The factors that affect gear wear are analyzed and three typical wear calculation formulations,including adhesive wear,abrasive wear and line-contact wear,are deduced.Based on the Archard's wear model,the numerical modeling and calculation of the adhesive wear of herringbone gears under quasi-static and dynamic loads are carried out.(2)Derivation of the geometric model for herringbone gears.Based on the generating principle of gear machining,according to the coordinate system transformation rules between tool and the gear blank,the expressions of spur gears profile are obtained,then the parametric model of herringbone gears are establised with the forming principle of herringbone gears.(3)Numerical calculation and analysis of quasi-static wear of herringbone gears.The symmetry error free herringbone gear is treated as one clearance groove and two standard helical gears with opposite tooth direction,and a general method for calculating the length of time-varying contact line is proposed based on the equivalent contact model of tapered rollers in opposite orientation of helical gear pair.The load of a single tooth pair according to the time-varying contact ratio method is calculated,and then the tooth pressure is obtained by the Hertzian contact theory.The sliding distance between two adjacent points in contact is calculated according to the single point observation method.The tooth wear depth of the herringbone gears under quasi-static load is obtained by the Archard's wear model,and the effects of various related parameters on tooth wear are analyzed.The results shown that a larger wear depth is generated at the root and the tip,while the wear depth at the root is larger than that at the tip,and that it trends to zero at the pitch line.Additionally,the wear depth decreases as modules,transmission ratios,face widths or input torques are increased,while the variation of helical angle or pressure angle has little influence on the wear depth reduction.(4)Numerical calculation and analysis of dynamic wear of herringbone gears.Based on the lumped mass method,the three-dimensional twelve-degree dynamic model of the herringbone gears is established according to meshing characteristics of load sharing for herringbone gears.And the dynamic meshing force is obtained by the ode45 function in MATLAB.Then,the dynamic wear depth is calculated using the dynamic meshing force calculated by the dynamic model instead of the quasi-static one.The comparision results shown that the wear depth difference value between dynamic and quasi-static loads decreases as modules,transmission ratios,face widths,helical angle,pressure angle and input torques are increased,while neglecting the effect of temperature,rotational speed has little effect on the wear depth under dynamic load.Based on the Archard's wear formula,the numeric calculation model of adhesive wear for herringbone gears under quasi-static and dynamic loads has been established in this paper.Analysis conclusions of tooth surface wear depth under different gear parameters and operation parameters are valuable for the wear resistance design of herringbone gears.