Efficient characterization of surface topography in cylinder bores

Abstract

Internal combustion engine cylinder bores are used here to study methods of minimizing the effort required to obtain three-dimensional (3-D) surface descriptions. After a brief experimental study to confirm that parameterization is not unduly sensitive to the geometry of various instrument configurations, two main issues are considered. Because true mapping is expensive, it would be desirable, at least for routine work, if it could be avoided. We show that very often a set of profiles, short of a true map, will supply an adequate description. Efficient processing requires that the sampled data spacing be as large as possible so as to minimize the size of datasets, which tend to be large for measurements over an area. Two algorithmic approaches to predicting a best sampling are investigated. One is a modification of a previously proposed approach based on cummulative power spectra and the other is a novel exploitation of “deep valley analysis.” Both are shown to be useful in practice, although the fomer is somewhat preferable because it is less application-specific.