Parametric design of boring bars with adaptive tuned mass dampers

Slender single point boring tools are damped with tuned mass dampers (TMD) to increase their resistance against chatter. A TMD with fixed parameters may weaken its effectiveness when it is coupled with spindles or bars with different lengths. This paper presents a tunable and parametric, digital design of boring bars. The large length to diameter boring bar is modeled using Timoshenko beam elements and the effects that the TMD head has on the dynamics of the assembled boring bar-TMD system is modeled using a derived analytical expression. A universal TMD head that consists of a carbide mass, oil pocket, and two rubber O rings with experimentally calibrated stiffness and damping as a function of compression is designed. The boring bar has an internal compression shaft that can be pressed against the O ring to vary its stiffness using an integrated power screw. The complete TMD boring bar system is mathematically modeled to determine the Frequency Response Function (FRF) including the required TMD natural frequency and damping ratio to maximize the chatter-free depth of cut. The digital model is verified by comparing the simulated and experimentally measured FRF of the TMD bars. The bars are also tested in boring experiments successfully.(c) 2022 CIRP.

Automated summary

This paper presents a tunable and parametric digital design of boring bars with tuned mass dampers (TMD) to increase their resistance against chatter. The mathematical model and experimental verification are used to determine the optimal TMD natural frequency and damping ratio for achieving chatter-free depth of cut.