Although vibratory finishing has been in commercial use for over 40 years, relatively little fundamental information is known about the process, and industrial practice remains largely based on empiricism and trial and error. An experimental investigation into the vibratory bowl finishing process was conducted using material removal rate and surface roughness as the dependent variables. Bowl performance can best be described in terms of acceleration and depends primarily on the feed weights used, while bowl loading has a relatively minor effect. Furthermore, small changes in bowl loading resulting from normal media wear can be neglected. Results showed that material removal rates were constant over time for aluminium, brass and steel and were sensitive to hardness and bowl acceleration. Surface roughness saturated after a fixed period and was primarily a function of material composition. Surface roughness did not appear to be sensitive to bowl acceleration.
In the present study, the DEFORM computer code was used to develop two-dimensional and three-dimensional ®nite element models for simulating external thread rolling. To simulate rolling in two dimensions, a plane strain model was used where the thread is assumed to form through progressive penetration of the blank surface using a parallel set of wedge-shaped indenters. To develop the three-dimensional model, a¯at-die rolling process was simulated which incorporated blank rotation, die movement and pitch angle on the die faces. Based on a comparison of thread form and microhardness with as-rolled threads, the plane strain model was found to provide a reasonable approximation of thread-rolling behaviour. Results obtained from the initial pass of the three-dimensional model are promising although progress is currently limited by the excessive computational time needed, frequency of remeshing and sliding at the die±blank interface.
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