CAUSAL ANALYSIS AND SOLUTION OF THE FAILURE OF SPROCKET DRIVERS IN A CLINKER SCRAPER CONVEYOR

Abstract

This study discusses the causal analysis and solution of the teeth failure in sprocket drivers in a clinker scraper conveyor of a cement plant. The failure consisted of the progressive surfacing shape loss of the teeth, progressively deteriorated to the operating conditions of the system, causing dynamic loads, which affected the mechanical transmission and the conveyor general performance. The assessment includes an analysis of the sprocket material and calculations of the stress fields in the teeth surface. The results show the failure is the result of using a sprocket material with high-abrasive resistance, but with yield strength lower than required for operating conditions. This failure can be addressed by replacing the entire sprocket that results in significant downtime and economic losses. The main contribution of this study is developing a solution based on the local quality principle to repair and prevent the failure without removing the sprocket. Furthermore, the analysis considers the surface forces resulting from the high friction coefficient caused by the lack of lubrication, resulting in stress values higher than the fluence limit of the teeth material. Therefore, the solution proposed is manufacturing the teeth with a different material with higher strength and abrasion resistance to prevent failures by deformation. The proposed solution takes advantage of the damaged sprocket wheels available in the plant. The teeth manufactured are welded in a plate that is later bolted to the sprocket wheel, which was previously machined to remove the damaged teeth and prepare the surface to assemble the new teeth.