Performance optimization of jaw-type rock crushing machine through shaft eccentricity redesign

Abstract

The recurrent failure of jaw-type crushing machine was traced to an inappropriate external shaft ratio and frequent wear of the jaw of the machine. Current jaw-type crushing machines are designed and constructed with spring steel was improvised with spring steel because of the scarcity of the required material to cast the jaw, which has to be imported whenever there is a failure. The analysis of the relationship between the life span of the jaw of the rock crushing machine to the shaft eccentricity was carried out to determine the external shaft ratio of the machine. The eccentric lobe to impact motion at various positions were analyzed and plotted out for both angular and linear displacements. The analysis and evaluation involved data collection from existing quarries. The results show that an external diameter/offset ratio within the average of 10:1 can be considered for the offset calculation of a jaw-type crusher shaft. The outcome of the result was used to redesign and develop a prototype crushing machine with better output crushing pressure of 13.1×10⁵ kN/m² and capable of crushing 425–569 kg of rock per hour, depending on the type of rock to be crushed. The machine performed exceptionally well with an efficiency of 95% and is relatively durable compared to high grade imported rock crushing machine.