Influence of rotational speed on the collision of mechanically plated galvanized layers based on discrete element method

Abstract

A discrete-element numerical simulation method was used to investigate the effect of plating barrel speed on the density of the galvanized layer during mechanical galvanizing. The motion behavior between the impact medium and the substrate in the plating barrel at five rotational speeds (20, 30, 40, 50, 60 rpm) was investigated. Laws of collision and contact force variation between the substrate and the impact medium were obtained. The average thickness, relative density, and average deviation of thickness of the galvanized layer specimens were obtained at the same rotational speed. The results were compared with those obtained from the simulation. The increase in barrel rotational speed decreased the number of contacts between the impact medium and the substrate, but made the change in the number of collisions more regular. This was conducive to a regular force on the zinc powder particles and made the galvanized layer more uniform and dense. The contact force between the impact medium and the substrate increased with an increase in barrel speed. At 20 rpm, the impact medium could not provide enough contact force to melt the zinc powder particles into the substrate surface. Contact force increased abnormally at 60 rpm, which caused some of the zinc powder particles that were attached to the surface of the substrate to fall off, which affected the plating thickening. The average thickness, relative density, and average deviation of the galvanized layer in the comparison test were consistent with the simulation results. From 30 to 50 rpm, the relative density of the galvanized layer increased with an increase in speed. The average thickness and relative density of the obtained galvanized layer were highest and the average deviation of the thickness was lowest at a barrel speed of 50 rpm. The relative density and uniformity of the galvanized layers were optimized.