Abstract
Very high quality standards need to be guaranteed for the manufacturing of cylindrical journal bearings due to their sensitive lubrication gap geometry as Iwamoto and Tanaka [1] have shown years ago. Even geometric deviations of a few micrometers can lead to considerable functional impairments. However, the designer’s actual geometric specification (technical drawing) mainly serves as information for the nominal geometry and important fits.
Within this research project, the main aim was to find out how permissible deviations on nominal operating parameters can be translated into permissible geometric shape deviations and their specifications as described in ASME Y14.5 [7]. The outcome was the development of a tolerance evaluation matrix which quantifies the relation between geometric and operating parameter deviations.
For this, existing references and standards dealing with geometric defects of journal bearings were analyzed as in [1], [2] and [3]. Firstly, to investigate the roundness deviation, we focused on the form of equal thickness because this occurs most often in the manufacturing process of cylindrical journal bearings. Later on, the shape deviation of parallelism (cone) and its combination with the roundness (equal thickness) were also investigated. After simulating the parameter variation of about 200,000 operating points with a hydrodynamic simulation program, called ALP3T, we synthesized a tolerance evaluation matrix for the application during the engineering and design process of cylindrical journal bearings.
