Functional tolerancing: Virtual material condition on complex junctions

Tolérancement fonctionnel : Etat virtuel au maximum et au minimum de matière pour les jonctions complexes

Robin Chavanne (1) , Bernard Anselmetti (1)

1 LURPA - Laboratoire Universitaire de Recherche en Production Automatisée

In industry, functional tolerancing of mechanisms is today more and more based on ISO GPS (Geometrical Product Specification) and ASME standards. In this context, the CLIC method (french acronym for " Cotation en Localisation avec Influence des Contacts ") has been developed in our laboratory since 1998. The current standards are incomplete to specify complex shapes, for example to define a datum reference frame on these surfaces. Using specific examples, the present paper outlines six proposals as possible extension of standards of tolerancing to describe the functional need for these links. Two main propositions are developed, the material conditions on complex surfaces and the definition of a new association criterion. Tolerance analysis models are presented; they must be consistent with respect to proposed functional specifications. The CLIC method [1] enables to elaborate a functional tolerancing based on notion of virtual boundary and a three dimensional tolerance analysis. Junctions between parts are described according to precedence order with primary, secondary and tertiary links. Geometrical functional requirements of the mechanism are imposed by the functional analysis. Intern requirements can be automatically detected by feature recognition (requirement synthesis) or imposed by the designer. Functional tolerancing relative to a given requirement is generated for each requirement (specification synthesis). Next, an equation is established to determine the effect of these tolerances on each functional characteristic (tolerance analysis). The set of equations allows then optimizing the tolerances and nominal dimensions parts in order to decrease the manufacturing cost (tolerance synthesis).

Mots clés: Functional dimensioning and tolerancing; tolerance analysis; GPS standards; complex links; virtual boundary 1 Scientifical context

Domaines: Sciences de l'ingénieur [physics]

Robin Chavanne, Bernard Anselmetti. Functional tolerancing: Virtual material condition on complex junctions. Computers in Industry, 2012, ⟨10.1016/j.compind.2011.10.004⟩. ⟨hal-01239318⟩