Evaluation of sphericity error from form data using computational geometric techniques

✍ Scribed by G.L. Samuel; M.S. Shunmugam

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 260 KB
• Volume: 42
• Category: Article
• ISSN: 0890-6955
• DOI: 10.1016/s0890-6955(01)00124-9

✦ Synopsis

The measurement data for evaluation of sphericity error can be obtained from inspection devices such as form measuring instruments/set-ups. Due to misalignment and size-suppression inherent in these measurements, sphericity data obtained will be distorted. Hence, the sphericity error is evaluated with reference to an assessment feature, referred to as a limacoid. Appropriate methods based on the computational geometry have been developed to establish Minimum Circumscribed, Maximum Inscribed and Minimum Zone Limacoids. The present methods start with the construction of 3-D hulls. A 3-D convex outer hull is established using computational geometric concepts presently available. A heuristic method is followed in this paper to establish a 3-D inner hull. Based on a new concept of 3-D equi-angular line, 3-D farthest or nearest equi-angular diagrams are constructed for establishing the assessment limacoids. Algorithms proposed in the present work are implemented and validated with the simulated data and the data available in the literature.