Research Of Design Theory And Experiments On Spiral Bevel Gears With High Contact Ratio

The spiral bevel gears are widely utilized in the intersecting axis transmission with its transmitting smoothly and higher strengthen,such the machinery as transports,machine tool,helicopter,mining and so on. With the development of machine manufacturing industry and acute competition of the international market,the spiral bevel gears,as the important basic parts in machine transmission,are required with higher and higher behavior in vibration,noise control and dynamic strength. This problem has long been paid attention by domestic and overseas many experts,and become a crux and top goal. It is well known that the gear contact ratio has a close relation with the gears transmission error,contact pattern,load distribution,influences the gears meshing smooth,noise,dynamic strength and stiffness. Based on development of the meshing theory,using TCA,LTCA and experiments,spiral bevel gears with high contact ratio are researched systematically. The influence of the high contact ratio design to the spiral bevel gears on contact performance,load distribution,strength and noise is analyzed,and design with high contact ratio and manufacturing method are presented. In terms of the developed software,we can design spiral bevel gears with the excellent meshing behavior,powerful bearing capacity and lower noise by the dialog between the operator and the computer.Li the thesis,the research achievements and creative contents include:1) In the tooth surface geometric design,the traditional conception that the contact path is perpendicular to the root cone is broken. In terms of the generating freedom-degree of the tooth surface,the sloping angle of the contact path is enlarged. Using the general machine-tool and cutter,the spiral bevel gears with the high contact ratio are designed and generated successfully.2) The spiral bevel gears design method based on the transmission error is proposed. The thesis analyzes deeply the inner relations of between the transmission error and themeshing behaviors,and the valuable information that the transmission error reflects,and investigates further influences of the manufacturing and installing errors,the various loads on the contact behavior of the spiral bevel gears with the high contact ratio. After that,the approach is presented,which assure that the spiral bevel gears have the high real contact ratio and the lower sensitivity to error.3) The method of geometrical and mechanical analysis is represented on the tooth edge contact in the gears transmission. Firstly,a simple and practical representing method of the tooth edge tangential vector is applied to replace the traditional differential formula,the simple solving technique of edge contact problem makes the geometric edge contact analysis of the complex curve surface realize. Secondly,using numerical searching and mathematical programming method solves the contact directions and loaded contact problem. Finally,whole numerical simulation method is provided for loaded tooth contact analysis of high contact ratio spiral bevel gears.4) Combining the local synthesis method for the machine-tool setting parameters,TCA and LTCA,and the numerical simulation of stress procedure constructs the optimal design circle with feedback. The developed software system provides an efficient design tool for the spiral bevel gears with excellent transmission behavior,high strength and lower noise.5) Using the practical products,we have done experiments and comparisons on designing and generating tooth,testing the contact ratio,tooth root stress,vibration and noise for the high contact ratio spiral bevel gears. These results prove that the high contact ratio transmission has some advantages on dynamic behavior and strength. The noise of the high contact ratio gears with the medial sloping contact path is reduced lower than 1-2 dB,and the noise of the gears with the large sloping contact path is lower ed more.