Using noncircular gears for the unloading door kinematics modification

Abstract

The paper introduces a new kinematics of the billet reheating furnace unloading door, by using a noncircular gear train in the drive mechanism. The main objective of the kinematics modification is to reduce the heat loss by increasing the unloading door speed, during the stroke, while kept it at the conventional value at the beginning and end of stroke. In order to modify the door kinematics, the drive mechanism output motion is controlled by noncircular gears whose transmission ratio is defined as a hybrid multiparameters function. A study is developed to analyse the influence of the defining parameters on the variation of the gears transmission ratio and on the discharging door speed, respectively. Based on the analytical study, a certain law of variation was chosen to describe the mechanism kinematics; in accordance to the kinematics variation, the mating noncircular centrodes/pitch curves were modelled and the gears teeth are generated, considering constant circular pitch and constant pressure angle, respectively.