New In-Situ Technology for Marine Diesel Engine Crankshaft Renovation and its 3D Surface Texture Model

Abstract

Repairing marine diesel engine crankshafts is a significant part of overall engine repairs and thus is very important for the ship building and ship repair industry. When a ship’s diesel engine is repaired, crankshaft journal surfaces must be renewed according to very precise geometrical and surface roughness requirements. Although current technologies are sufficient to meet these requirements, they are very time consuming and consequently expensive. A comprehensive research into the surface machining of marine diesel engine crankshaft journals allowed to improve technological processes and to identify respective surface roughness parameters, as well as to provide appropriate technological recommendations. It is important to note that crankshaft journal surfaces must be seen as 3D objects, whose micro-topographical surface roughness parameters have to be defined so that they reflect the actual surface. To summarize all available scientific research in this field, we can state that there has been no analysis into the impact of technological regimes on the surface micro-topography of marine engine crankshaft journals. Bearing in mind the aforementioned arguments a study has been launched to develop a novel grinding technology, enabling diesel engine crankshafts with medium-sized crankpin journals to be repaired directly inside the engine housing. This paper covers the following issues: 1) Description of the novel technological equipment for crankshaft journal grinding; 2) 3D roughness model of the crankshaft journal surface; 3) calculation of 3D parameters based on practical metrological and technological characteristics. This technology saves significant financial resources as well as reduces engine repair time. By solving problems related to surface accuracy, it is possible to considerably improve the crankshaft machining process, along with the performance of maintenance operations and consequently the overall quality of repair work. In this paper, the crankshaft journal surfaces will be defined using 3D surface roughness parameters.