Product and process modeling : simulation of a manufacturing process for tolerance analysis and synthesis
Résumé
The choice of a manufacturing process (machine-tools, cutting tools, part-holders,
process plan) which allows the production of parts conform to the objective in term of
quality and price depends on many criteria. One of these criteria is the respect of the
functional tolerances of the part. To check this point the manufacturing process is simulated
(positioning and machining operations). The result of this simulation is a Model of
Manufactured Part (MMP). The deviations of all the surfaces of the MMP are described
with regards to their nominal position (nominal part) using a small displacement torsor.
Then, for all the functional tolerances to be verified, a virtual gauge is created and
assembled with the MMP and the gap between the tolerance zone and the toleranced
surface is calculated. The verification of each tolerance is provided by a system of
inequalities representing the non-contact conditions between the toleranced surface and the
tolerance zone limits. The ability to machine a series of parts closed to the functional
tolerances being verified, the ISO or non-ISO manufacturing tolerances to define the
workpiece at each set-up is determined. These tolerances are useful to follow the
conformity of the workpiece at each step of the machining process.