Latent heat storage with shape memory alloy thermal switch for thermal error compensation on linear direct drive

In machine tool manufacturing, the majority of geometrical errors of machined workpieces are caused by thermal effects. External and internal heat sources within the machine tool induce time variable heat losses that cause thermoelastic deformations in the surrounding machine structure. The resulting unsteady displacement fields lead to decreased position accuracy and hence compensation approaches are needed in order to compensate for the thermally induced error. One approach is to use latent heat storage to increase the thermal inertia in a certain temperature range. However, a permanent connection between heat source and heat storage is not always convenient. The proposed approach therefore considers latent heat storage in combination with a shape memory alloy-actuated switch mechanism controlling the heat flow. For the latent heat storage, paraffin-based phase change materials infiltrated in aluminum foam structures are used. Performance and efficacy of the realized compensation components and the shape memory alloy actuators are experimentally validated.