Precise model of HSC Machining Centre for aerospace parts machining

This article shows the aspects of precise modelling of precise High-speed Machining Centres for High-Speed Cutting (HSC) of parts used in the aerospace industry. The main focus was made on the thermal errors having a dominant influence on the precision of machining. Main assumptions for a hybrid thermal model of a centre thermal behaviour have been stated, taking into account the characteristics of heat sources. On the example of a 3-axis machining centre, measured runs of heating up and heat displacements have been shown, compared to these determined with the use of simulations of a behaviour in assumed working conditions. A special attention was drawn to the phenomena taking place in motorspindles, as well as to the displacements of a spindle face during high rotational speeds of spindles and step changes of rotational speeds. The significance and influence of the bearing preload and centrifugal forces on the spindle axial displacements was shown, which is decisive on the precision of part machining. Additionally, it was shown that the important component of a machining error is an error of spindle position identification by means of a linear encoder, resulting from the thermal deformation of a centre body, to which a quartz linear encoder is fixed