Evaluation of thermo-energetic behavior for demand-oriented operating of machine tool cooling systems

In state of the art machine tools, structural thermal displacement is commonly reduced by cooling and tempering measures. The application of these measures frequently counteracts the original goal of energy efficiency. To design demand-oriented cooling systems, this paper presents a method to evaluate cooling measures and control parameters by means of a variance-based sensitivity analysis regarding the thermo-energetic efficiency. The evaluation is carried out by using the example of a machine bed made of high performance concrete. The integrated fluid-air cooling system with fan speed control and the bed structure are modelled by lumped elements. In addition to the PID-control of the cooling fluid temperature, the evaluation considers a two-position control of separately controllable cooling circuits and the influence of ambient temperature. The criteria to evaluate are temperature differences within the machine structure, the dissipated heat and their proportions to deployed electrical energy.