Determining geometrical deviations of crankshafts with limited detection possibilities due to support conditions

Abstract This article is a continuation of previous research in which we analysed the effect of deflections and elastic deformations caused by unsupervised support conditions on the measurements of geometrical deviations of large crankshafts. Supporting the shaft using a set of rigid supports at the same height limited the ability to detect deviations in the pin axis position and pin profile. Formula for supporting crankshaft measurements was proposed using the results and metrology fundamentals, which allowed the accurate assessment of the geometric state under such conditions. The results provide solutions for measuring large crankshafts while eliminating the imperfections of current shaft measurement techniques. In result a high correlation (correlation coefficent at level 0.9935) with datum-based method was obtained. Therefore it was stated than proposed formula largely eliminates the disadvantages of shaft measurements using V-blocks with rigid supports.