Determination of Geometrical Deviations of Large-Size Crankshafts with Limited Detection Possibilities Resulting from the Assumed Measuring Conditions

This article deals with the geometrical deviation measurements of crankshafts of large marine engines fuelled with conventional or alternative fuels, taking into account the problem of their deformability. Since the detectability of geometrical deviations of a crankshaft supported by prisms depends largely on the support conditions assumed and the parameters of the method, the study was carried out for two cases of crankshaft support. The first case concerned measurements of the main journals of a crankshaft seated on a set of supports pre-positioned at an equal height. In contrast, the second case involved measurements of the main journals of a crankshaft seated on supports pre-positioned at various heights. In particular, the research focused on evaluating the effect of sensor location angle on the results of measurements of deviations and contour profiles of the crankshaft main journal system. The results of the research are the developed procedures, the application of which in practical measurements under workshop conditions, where there is no access to coordinate measuring machines, enables correct interpretation of the measurement results and evaluation of the geometrical state of the measured crankshaft.