In many applications, crowned profile geometries are employed to optimize load carrying and durability. As an example, crowned profiles are used in roller bearings to control local contact stresses. As the image below shows, the shape of the roller bearing surface relates to the stress pattern that develops when the bearing is pressed into its mating surface.
The challenges of assessing crowned profiles
The specification, measurement, and analysis of the crowned profile shape poses four challenges:
- The geometry is not necessarily a simple equation. This shape is generally defined by a lookup table of diameters at various axial positions, such as the one below:
- The crowned shape does not always have a uniform tolerance zone along its length. Typically, the tolerance zone is much tighter in the center of the profile then relaxes near the edges.
- The roller bearing has a length tolerance that can be much wider than the profile will allow. However, the curvature of the crown must be maintained at the edges despite variations in length.
- Along with the profile “shape” or geometry, the surface texture (roughness and waviness) is critical to the function of the surface.
CrownView addresses the unique challenges of analyzing crowns
While some surface analysis software packages have been able to address limited aspects of crowned profiles, none were really designed to overcome all of the complications listed above. The result has been that manufacturers needing to control crowned profiles have had to generate their own application-specific solutions.
Digital Metrology’s CrownView software was developed specifically to fill this void by analyzing crowned geometries. The image below shows the CrownView interface. It shows, at a glance, the profile within its tolerance band, the roughness and waviness profiles, and the error plot, along with key statistics.
CrownView accommodates non-uniform tolerance zones. It allows for “dilation” at the profile center to accommodate the surface’s length tolerance.
The software also helps manufacturers target highly stressed areas of the surface. “Morphological filtering” is used to detect sharp waviness peaks, which can then be identified and controlled using the Wcvx parameter.
CrownView can accept data from most commercial profiling instruments. Contact Digital Metrology today to see how CrownView can help you better understand and control your complex geometries.