Análise experimental em um cilindro de varetas de uma colhedora de café para diagnóstico de falha

Abstract

Coffee harvesters work with vibration system in order to promote the breaking of the grains peduncle. The vibration system is usually coupled to the end of an axis, called a rod vibrating cylinder. This cylinder can present failures on duty, which usually occurs due to fracture failure in the weld region between the cylinder and its flange. It is observed that this type of failure occurs in a short time, before 12 months of constant work, which requires a failure diagnosis. The main objective of this work is to perform failure diagnosis in the vibrating rod cylinder of a coffee harvester. To this end, a the fracture mapping was performed and samples were made specimens for destructive and non-destructive mechanical tests, such as tensile testing, chemical analysis of the pipe and flange materials, metallography of the welded joints and hardness testing Vickens and Brinell. Through these tests, it was observed problems due to the welding process applied between the rod cylinder and the flange, and to manufacturing defects of the axle (arising from the casting process). As a result, it was observed a probable fatigue failure process leading to a short service life in the cylinder-flange assembly. To solve this problem, a welding procedure (EPs) is proposed to improve the fabrication process of the rod cylinder.