DEVELOPMENT OF A PROTOTYPE JAW- TYPE ROCK CRUSHING MACHINE

Abstract

Surface rocks are abundant in the country and can be readily employed to meet the nation’s vast construction needs if the appropriate machinery is in place. Rock crushing machinery is presently imported, making it to be out of reach for low and medium scale investors. Maintenance cost is very high because critical components must be imported and local capacity for their fabrication does not yet exist. Therefore there is need to develop locally, a rock crushing machine at affordable rate to convert the abundance surface rock to a useful engineering materials. In this project, a prototype rock crushing machine has been designed and constructed with output crushing pressure (C.P) of about 13.1 x 105 kN/m2 and capable of crushing 425 to 570 kg of rock per hour, depending on the type of rock to be crushed. All the components of the machine were designed and constructed from locally sourced materials. The jaws of the crusher is normally made from manganese steel which is scarce locally, The jaws in this work has been made based on improvisation of spring steel materials from scrap yards to reduce cost. The degree of eccentricity of the shaft (that is, the deviation from a circular shape or pattern) was adjusted as part of the redesigning process to enhance effective crushing and durability of the shaft. The power rating of the machine is 4.0 kW and its alternate current (AC) electric motor requirement is 240 volts and should be supplied within a frequency range of 50 - 60 Hz. This design equally made room for alternative drive (i.e. the use of manual drive) in case of power outage, capable of delivering Crushing Pressure (C.P) of about 6.1 x 105 kN/m2. The total cost for constructing this jaw type rock crushing machine was about N146,686:27.