Effect of Cross Modification on the Quasi-Static and Dynamic Characteristics of Helical Gear System

A nonlinear excitation model coupling mesh stiffness and tooth modification is established based on loaded tooth contact analysis method. The effects of cross modification on load distribution, mesh stiffness and loaded transmission error of helical gear are investigated. Considering shaft deflection, a generalized finite element model of helical-rotor-bearing system is developed based on Timoshenko beam theory. By separating transmission error exciting force, the differential equation with variable coefficients is transformed into ordinary differential equation, so the equation is solved fast. The best cross modification parameters are obtained based on graphical method with the objective of minimum of fluctuation of transmission error exciting force. The results show that mesh stiffness fluctuation is not the dominant factor affecting the vibration of gear transmission with modification, the system vibration is determined by the fluctuation of transmission error exciting force, and the cross modification not only weakens the gear mesh stiffness less, but also decreases the mean square error of dynamic transmission error and the fluctuation of dynamic bearing load significantly, thereby reduces gear transmission vibration and noise.