This paper systematically investigated canning issues at different stages of converter manufacturing processes and operations. Commonly used converter canning processes, which include tratditional clamshell style and torniquet wrap, are included in the study. Manufacturing processes were simulated, and the effect of shell closing speed and substrate tolerances were studied. Using a previously developed mat material model, viscoelastic behaviour, as well as the unique expansion characteristic of the intumescent mat under high temperature, are included in the simulations. Lab testing of the mat material at different loading speeds was conducted to obtain the visco-elastic properties. These will allow the studies of the effect of closing speed on the peak pressures during canning processes, as well as the pressures during heating and cooling. The uneven distribution of pressure and gap on the converters are investigated, and the results compared with Tekscan and gap measurements from the production line. Good correlations between simulation and test/production results are observed. The following conclusions can be made from this study. 1. The analysis procedure successfully simulates the clamshell and torniquet wrapping processes; uneven pressures and gap distributions can be predicted from simulations; simulations correlate well with the test/production results. 2. Uneven pressure distributions will cause shear stresses in the substrate. The maximum shear stress in the converter should be examined and compared with the substrate shear strength. The tolerances on the substrate have significant effect on the canning pressure and substrate shear stress in clamshell converters. 3. The converter shell closing speed during the clamshell canning process affects the canning pressure and substrate shear stress; the peak pressure and shear stress increase as the closing speed increases. However, the relaxed pressure does not change very much as the closing speed changes. 4. The simulation predicts the effect of torniquet pulling forces on the gap and canning pressures, which have a direct benefit in helping manufacturing set-ups. 5. The current minimum isostatic strength is measured at very low loading speed. For clamshell canning, higher loading speed may be more appropriate.
Catalyst converter canning simulation studies
2003
13 Seiten, 19 Bilder, 2 Tabellen, 6 Quellen
Aufsatz (Konferenz)
Englisch
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