Tooth Modification Design And Optimization Of Involute Straight Bevel Gear

Because of involute gears have good transmission performances, which are easy tomanufacture, installation, measurement, used interchangeably and so on, so they are widelyused in various transmissions. Involute straight bevel gears are commonly used in parts ofintersecting shaft drive such as automobile differential mechanism, the transmission qualitywill directly affect the performance of the entire gear system. With the development of industry,the characters of transmission accuracy of movement, drive stability and carrying uniform arerequired improved, therefore, it is necessary to do in-depth research on the dynamiccharacteristics of involute straight bevel gear.Because of the impact of manufacturing errors, installation errors, elastic thermaldeformations and thermal deformations and so on, the straight bevel gear pair will appearserious phenomenon of meshing interference and impact, uneven load in meshing process and“end contact”. Nevertheless, through modification can improve above phenomenonseffectively, widen the range of application of gears and improve the quality of thetransmission at the same time. Therefore, this paper take precision forging involute straightbevel gears as research object, based on the principle of gear meshing, gear modificationtheory and finite element theory, using3-D solid modeling techniques and numericalsimulation techniques to research the characters of gear pair, for the purpose to improve thedrive stationarity and homogenize tooth loads in meshing process of gear pair, throughin-depth research on the elastic deformations and stresses distribution so as to obtain themodification influence on dynamic meshing performances, and then get the excellentmodification tooth. Then we adopt target variable curvature crowning according to thespecific conditions of bevel gear in order to achieve the desired modification effect, and thenperfect the modification theory of involute straight bevel gear.Firstly, according to the bevel gear space spherical involute equations and structuralparameters, establishes accurate3-D solid bevel gear models based on SolidWorks, thismethod can solve the problem of lack of precision because of back cone involute instead ofthe space spherical involute. Deformations and stresses of gear are analyzed based on theHertz theory and the theory of mechanics of materials. Subsequently, describes the contact finite element theory, establishes finite element model of bevel gear pair based on theANSYS/LS-DYNA, and then calculates the results of dynamic contact finite element model.These results provide the basis for solid modeling, finite element modeling and simulating ofmodification bevel gear.Although our research group have done in-depth research on isometric modificationdesign and technology of involute straight bevel gear, they has not concluded the optimalisometric modification parameters on specific working conditions, which are determinationreasonable of isometric modification position, amount of modification and modificationheight. Therefore, this article select parameters within a reasonable range using empiricalmethod, using orthogonal design to optimize isometric modification parameters, and gettingthe importance of each modification factor for influence on the dynamic characteristics of thebevel gear and the optimal isometric modification parameters, and obtaining the optimalmodification tooth on specific conditions through contrast the comprehensive modificationeffect of symmetric crowned gear and the isometric modification gear. These conclusions canprovide some references for perfecting isometric modification theory of straight bevel gear.Due to the gear pair is affected by various installed errors, manufacturing errors andcomplex loads in working process, these affections will lead to the tooth loads distributionvery complex, meanwhile, the errors are not completely in accordance with the symmetricdrum-shaped distribution. Therefore, although the symmetrical crowned bevel gear canimprove the state of shock and load distribution to a certain extent, it can not obtain theoptimal modification effect on specific working conditions. In this paper, we consider theelastic deformations of the axle effect on the modification, then adopt target variablecurvature crowning according to specific working conditions of bevel gears in order toachieve the desired modification effect, and perfect the modification theory of involutestraight bevel gear.Because of the complexity of the variable curvature crowning, the conventional methodof using space spherical involute stretch and sweep standard gear model to remove toothsurface materials has been unable to meet the accurate requirements of the variable curvaturecrowned model, at the same time, this method can not realize parametric modeling ofmodification bevel gear. Therefore, this paper deduces the tooth surface equation of variable curvature crowned and puts forward an easy to realize parametric modeling method of targetaccurate variable curvature crowning for involute straight bevel gear in accordance withspecific working conditions based on ANSYS/LS-DYNA, Imageware, Matlab andSolidWorks. This method can realize the accurate modeling for variable curvature crownedinvolute straight bevel gear and ensure the accuracy of modification gears and follow-up finiteelement simulation, meanwhile, it provides theoretical basis for parametric modeling ofvariable curvature crowned involute straight bevel gear. Finally, the validity and superiorityof variable curvature crowning is verified through research on the results of dynamic contactfinite element analysis under specific working conditions.