applied sciences Article Method to Increase the Accuracy of Large Crankshaft Geometry Measurements Using Counterweights to Minimize Elastic Deformations Leszek Chybowski * , Krzysztof Nozdrzykowski, Zenon Grz ˛adziel , Andrzej Jakubowski and Wojciech Przetakiewicz Faculty of Marine Engineering, Maritime University of Szczecin, ul. Willowa 2-4, 71-650 Szczecin, Poland;
[email protected] (K.N.);
[email protected] (Z.G.);
[email protected] (A.J.);
[email protected] (W.P.) * Correspondence:
[email protected]; Tel.: +48-914-809-412 Received: 26 May 2020; Accepted: 7 July 2020; Published: 9 July 2020 Abstract: Large crankshafts are highly susceptible to flexural deformation that causes them to undergo elastic deformation as they revolve, resulting in incorrect geometric measurements. Additional structural elements (counterweights) are used to stabilize the forces at the supports that fix the shaft during measurements. This article describes the use of temporary counterweights during measurements and presents the specifications of the measurement system and method. The effect of the proposed solution on the elastic deflection of a shaft was simulated with FEA, which showed that the solution provides constant reaction forces and ensures nearly zero deflection at the supported main journals of a shaft during its rotation (during its geometry measurement). The article also presents an example of a design solution for a single counterweight. Keywords: large crankshafts; minimization of elastic deformation; increasing measurement precision; device stabilizing reaction forces; measurement procedures 1. Introduction The geometries of small machine components are easily measured because they are very common in mechanical engineering, and the relevant measurement instruments are available [1,2].