Study on System Stiffness Enhancement of Zero-drive Gear Hobbing Machine

In high speed and high precision zero-drive hobbing machine,the hob-spindle and the work-table are directly linked to the motors.This structure has ability to avoid bad influence on rotational accuracy and dynamic stiffness caused by rotational error and backlash error of gears.Since equivalent moment of inertia of both the hob-spindle and the worktable are very small,rotating vibration caused by load torque fluctuation becomes large.A variable inertial damper,whose viscous damping coefficient could be adjusted by changing the gap between inertia wheel and motor spindle,was designed in servomechanism and was directly attached on the motor spindle.The structure of variable inertial damper was proposed,and the mathematical model of servo system with inertial damper was built.By using theoretical analysis and system simulation,it is demonstrated the validity of variable inertial damper on the aspect of increasing the system stiffness of zero-drive hobbing machine.