In order to further improve the damping characteristics of boring bar, the structure of built-in damping boring bar with dual absorbers was considered. Establishing the simplified dynamic model of shunt-wound dual boring bar,the function expressions of the boring bar’s relative amplitudes of the master system and external excitation frequency can be concluded. In order to get the minimum relative amplitude,this function needs to be minimized. Then the optimized parameters can be obtained. As to 3-DOF system of medium complexity,the global optimization search numerical method which suitable for 2-DOF is no longer applicable. To resolve this problem,using branch and bound algorithm after considering various factors, a theory minimal relative amplitude value and a set of optimum parameters were got. For the broadband damping effect,the amplitude-frequency response curve area minimization method is also required to check the parameters value. Drawing the amplitude-frequency response curves of the optimal dual damping boring bar and the same size single damping boring bar,it can be seen that amplitude of the optimization boring bar is smaller than the latter. It illuminates that this is a more effective way.
