Highly Integrated High Precision Fluidic Feed Axis

Current machine tools for micro manufacturing feature unfavorable ratios of installation space to work space as well as moving masses compared to the work piece mass. Therefore, these machines show potential for optimization [1]. Machine tool components leading to these drawbacks are the currently used feed axes. The required features of such feed axes for micro manufacturing comprise high functional integration, high damping and high precision. Compared to electromechanically build up feed axes incorporating high installation space as well as small damping ratios due to linear guide rails, hydraulic feed axes feature the potential of a high force density and high damping ratios. However, a drawback is the poor precision. At the wbk Institute of Production Science Karlsruhe a novel approach has been realized: A highly integrated hydraulic feed axis with high compactness due to the hydraulic force density. Additionally, it features high functional integration by piezoelectric seat valves built into the piston rod and an integrated hydrostatic guidance system. Within this paper, the approach as well as the measurement results of the prototype of the feed axis by the Institute of Production Science are shown. Furthermore, it addresses the feed axis's properties such as positioning errors, performance and inaccuracies. In the end, an outlook will be given on further ongoing research activities regarding an upgrade enabling an intelligent, active manipulation within the hydrostatic guidance system to compensate the errors of the feed axis.