Characterization of an Eigenfrequency Adaptable Machine Tool Carriage

Current machine tools feature fixed eigenfrequencies which are often excited by high performance cutting operations leading to unfavorable process conditions or poor workpiece quality, for example, due to chatter. Approaches to resolve this problem either constitute in changes of the process conditions, adaptable auxiliary mass dampers or vast and expensive changes within the machine tool structure. All of these approaches are either expensive, lead to a lower cutting ability or do not address the underlying problem.A novel approach to avoid chatter is described in this paper. It deals with a frequency adaptable machine tool carriage made out of hollow carbon fiber reinforced plastic (CFRP) profiles. This light structure enables chambers to be filled separately. This allows a tuning of the eigenfrequencies by pumping fluid into the chambers of the carriage reducing the eigenfrequencies. The CFRP structure has a high “added mass to component mass” ratio due to the high stiffness in relation to the density of the CFRP. Thus shifting the eigenfrequencies on a larger scale in comparison to the carriages of the same kind but made out of steel or cast iron.Within this paper, the approach as well as measurement results of the prototypical realization will be presented. The paper will address measurements of sloshing, the influence of added fluid mass regarding different filling levels and the influence of the control behavior of the feed axis. The paper shall conclude with a comparison of the measurements to a similar machine tool carriage made out of steel. In the end, an outlook on upcoming research topics and activities shall be given.