Simulation and development of an active damper with robust μ-control for a machine tool with a gantry portal

Machine tools are generally used with process parameters that are as productive as possible yet stable. One way to raise productivity is to increase the process parameters like cutting speed or depth of cut (DOC). However, this approach will lead to process instabilities sooner or later. An increased rotational speed of the spindle will excite higher eigenfrequencies depending on the tools teeth count. In combination with higher cutting forces resulting from a deeper DOC, the process can become instable because of chatter or other oscillations and vibrations of the machine tool. This paper describes the identification of a critical eigenfrequency and corresponding eigenmode. An active damper was then developed to mitigate the negative effect this critical eigenfrequency has including a robust controller which protects the process from instabilities through changing eigenfrequencies caused by changing machine positions. It will also enable increased process parameters for a higher productivity of the machine tool. A simulation environment of the active damping system with a classic control and a robust \(\mu\)-control was developed. The damper was applied to the machine tool and tested.