Moses Frank Oduori

Effect of runner design on mechanical properties of permanent mould aluminium castings

Abstract A comparison of the influence of different runner designs on the mechanical properties of aluminium castings has shown that filtered rectangular runners (FRRs) yield aluminium castings with higher and more reliable mechanical properties than the conventional unfiltered rectangular runners. Unfiltered vortex flow runners have also been shown to improve the reliability of the modulus of rupture of cast aluminium alloys over unfiltered rectangular runners. In the present paper, experimental results of a comparative study on the effect of the unfiltered vortex flow and FRR designs on the tensile strength of permanent mould aluminium castings are reported. The results show that an FRR yields castings with higher and more reliable tensile strengths than the unfiltered vortex flow runner. Castings poured into a mould with an FRR had strengths between 269 and 291 MPa and a Weibull modulus of 50·2 while castings poured into the vortex flow runner had strengths between 255 and 280 MPa and a Weibull modulus of 40·3.

Analysis of the single toggle jaw crusher kinematics

Purpose – This paper aims to obtain equations that can be used to describe the motion of any given point in the swing jaw of a single toggle jaw crusher. Design/methodology/approach – The swing jaw drive mechanism of a single toggle jaw crusher is modelled as a planar crank and rocker mechanism with the swing jaw as the coupler link. Starting with the vector loop closure equation for the mechanism, equations of the position, velocity and acceleration of any given point in the swing jaw are obtained. Findings – Application of the kinematical equations that were obtained is demonstrated using the dimensional data of a practical single toggle jaw crusher. Thus, a description of the kinematics of any given point in the swing jaw of a single toggle jaw crusher is realized. Originality/value – The model of the single toggle jaw crusher mechanism as a planar crank and rocker mechanism is a realistic one. The equations obtained in this paper should be useful in further studies on the mechanics and design of the s...

Wire Rope Selection for Manual Winch Application

Purpose – The purpose of this paper is to demonstrate the application of analytical decision making during the selection of engineering entities in an engineering design setting.Design/methodology/approach – The paper develops a quantitative method for wire rope selection and uses handbook data to demonstrate the use of the method in selecting a suitable type and size of wire rope for the hoisting/hauling mechanism of a hypothetical manual winch.Findings – Wire rope data can be processed into forms that are more readily useable in a quantitative selection method. Moreover, computer software such as Microsoft Excel may be used in the selection process, so long as the data are in suitable form.Originality/value – The selection of engineering entities often occurs in engineering design processes. An information processing approach to wire rope selection has been developed and demonstrated. The method demonstrated in this paper should be applicable in other situations in which a need for the selection of engi...

The kinematics and mechanical advantage of the double-toggle jaw crusher:

The purpose of this article is to obtain a comprehensive mathematical description of the kinematics of a double-toggle jaw crusher. The driving mechanism of the crusher is modeled as a planar six bar linkage. Two closed position vector loops that characterize the configuration of the mechanism are used to derive expressions for the angular position, velocity and acceleration of the moveable jaw. Dimensional data of a typical double-toggle jaw crusher are used in the derived mathematical expressions to demonstrate their application. Moreover, starting with the equation for the angular velocity ratio of the moveable jaw, with respect to the input crank, an expression for the ideal mechanical advantage of the crusher is derived. The expressions derived in this paper provide the foundation for further investigations into the mechanics and the design of the double-toggle jaw crusher.

Analysis of the Single Toggle Jaw Crusher Force Transmission Characteristics

This paper sets out to perform a static force analysis of the single toggle jaw crusher mechanism and to obtain the force transmission characteristics of the mechanism. In order to obtain force transmission metrics that are characteristic of the structure of the mechanism, such influences as friction, dead weight, and inertia are considered to be extraneous and neglected. Equations are obtained by considering the balance of forces at the moving joints and appropriately relating these to the input torque and the output torque. A mechanical advantage, the corresponding transmitted torque, and the variations thereof, during the cycle of motion of the mechanism, are obtained. The mechanical advantage that characterizes the mechanism is calculated as the mean value over the active crushing stroke of the mechanism. The force transmission characteristics can be used as criteria for the comparison of different jaw crusher mechanism designs in order to select the most suitable design for a given application. The equations obtained can also be used in estimating the forces sustained by the components of the mechanism.