Evaluation of form data using computational geometric techniques—Part II: Cylindricity error

The form tester having a straight datum in addition to rotational axis provides the cylindricity data. Due to misalignment between axis of the component and instrument axis, and size-suppression inherent in such measurements, a limacon-cylinder has to be used for cylindricity evaluation. For the first time, an attempt has been made in the present work to establish the limacon-cylinder using computational geometric techniques. Concepts involved in the construction of limacon from 2D control hull as brought out in Part I are further extended in this Part II to establish the limacon-cylinder. The algorithms developed in this paper have been applied for minimum circumscribed, maximum inscribed and minimum zone evaluations of the data available in the literature. The proposed algorithms are fast and yield accurate results, and can be implemented in computer-aided form measuring instruments.