Research On The Effects Of Spiral Bevel Gears' Tooth Surface Modification On Contact Characteristics

Spiral bevel gears are widely used in various transmission systems due to their brilliant performance in terms of transmission ratio,loading capability and so on.In this fast-changing era,spiral bevel gears,as the major parts of transmission systems,are considered to be the critical components in mechanical machines.With the high-speed advancement of modern technology,more and more mechanical machines are required to present better work performance.As the major components of these machines,the performance of spiral bevel gears plays a significant role in machines' comprehensive performance,as a result,optimizing spiral bevel gears' work performance is becoming practically necessary and meaningful.Spiral bevel gears' contact characteristics are mainly decided by their tooth surfaces,their contact characteristics can be optimized by tooth surface modification,which consequently leads to lower vibration and noise.Based on spiral bevel gears' manufacturing theory and modern free-from gear generator,this dissertation studied the effects of machine settings high-order modification and tool modification on spiral bevel gears' contact characteristics,providing reliable theoretical references to the better optimization of spiral bevel gears in practice.The major completed contents of this dissertation can be summarized as follows:1.In the light of gear meshing theory and spiral bevel gears universal generator model,the relative position of machine,tool and workpiece in the generating process was analyzed under the basic analysis model,then,the relative velocity with the consideration of machine settings dynamic polynomials was deduced,finally,spiral bevel gears' tooth surface equations were established,furnishing theoretical basis to the research on tooth surfaces modification,contact analysis and 3D-modeling.2.High-order modification were applied to radial setting,machine center to back,sliding base setting and blank offset individually,serving the purpose of changing generating relative motion.The effects of machine settings high-order modification on tooth flank were investigated by computing tooth flank nominal deviation and constructing error surfaces.With the application of contact theory,tooth contact area,transmission error and VH adjusting figure were solved,as a consequence,the effects of machine settings high-order modification on contact characteristics were discussed,providing relative scholars with some supporting materials about applying machine settings high-order modification correctly in practice.3.With the intention of altering 1st surface in gears manufacturing process,toprem tool and circular tool were introduced and tool equations founded consequently.The accurate grid planning were realized by computing tooth surfaces boundary lines,further,the complete tooth surface model were built.The FE models were constructed through single-tooth meshing approach,then,FE analysis setting and the contact characteristics computing methods were also given.At last,the corresponding conclusion was drew after thoroughly analyzing the effects of tool modification on spiral bevel gears' contact characteristics.4.Considering the research accomplishments of machine settings high-order modification and tool modification,Spiral bevel gears' machine-tool setting were numerically optimized through the least squares method and high-order modification method,then,the contact characteristics after machine-tool setting optimization were checked by FE analysis,the final results shown the entire work performance was enhanced,verifying the validity and effectiveness of the demonstrated achievements.