Contents of Journal of Mechanical Engineering 55, 1 (2004) 


 

DEEPAK, K. P., NIBEDITA, D., RAJAT, K. B.: Predicting material 
removal in electro-discharge machining                                      1 

HAMMAD, M. M. S.: A study on possibility of using reversed heat 
treated steel with little carbon for manufacturing functional 
parts of agricultural machines                                             23 

ADAMCZAK, S., MAKIELA, W.: Influence of work centre displacements 
on the estimation of roundness profiles measured with reference 
methods                                                                    33 

BAHLAOUI, A., RAJI, A., HASNAOUI, M.: Coupling between mixed 
convection and radiation in an inclined channel locally heated             45

Abstracts



Predicting material removal in electro-discharge machining

KUMAR PANDA DEEPAK, DASH NIBEDITA, KUMAR BHOI RAJAT

Various researchers have predicted the crater under single spark by considering the thermal erosion theory. Theoretical models have been developed by solving the transient heat conduction equation considering suitable assumptions with appropriate initial and boundary conditions. For the sake of close-form solution, too many assumptions and simplified initial conditions resulted in solution, which is far from reality. In actual machining, the growth of plasma channel, energy sharing between electrodes, vaporization of workpiece, formation of recast layer, temperature sensitivity of thermal properties of material are few physical phenomena encountered which have not yet been considered mathematically. Therefore, direct correlation of theoretical prediction of material removal with the experimental results has not yet been done. In such circumstances an attempt has been made to apply the factorial design in conjunction with multiple regression to develop response equation to predict the material removal rate.

A study on possibility of using reversed heat treated steel with little carbon for manufacturing functional parts of agricultural machines

MOH'D M. S. HAMMAD

Through using reversed heat treatment, possibility to improve the mechanical characteristics of steel with little carbon and using thereof in field of manufacturing functional parts of agricultural machines, which have direct contact with soil, was studied.

Experiments proved that reversed heat treatment helps to increase hardness of a little carbon steel as well as its wear resistance against abrasive wear in the soil through depending on hardening temperature and how its internal structure is distributed.

Upon reversed heat treatment of a little carbon steel, the best results of hardening were obtained from 780oC, where increase of hardness presented 35 % and increase of resistance against abrasive wear in the soil represented more than five doubles compared with ferrite - pearlite steel, which is used for manufacturing of agricultural machines parts. This fact affirms possibility of improvement of mechanical characteristics of a little carbon steel and possibility of using thereof in agricultural mechanism field.

Influence of work centre displacements on the estimation of roundness profiles measured with reference methods

STANIS\LAW ADAMCZAK, WLODZIMIERZ MAKIELA

Studies concerning estimation of roundness profiles by means of reference methods show that constant displacements of the centre of a measured work are observed during measurements. The displacement is caused by errors of determination of method parameters (angles \alpha and \beta ), tolerance of the measured work and the mating of the work irregular profile with the fixed points of the support. This paper deals with the influence of the above mentioned factors on the accuracy of estimation of a roundness deviation. The theoretical analysis supported by computer-aided tests leads to some practical conclusions.

Coupling between mixed convection and radiation in an inclined channel locally heated

AHMED BAHLAOUI, ABDELGHANI RAJI, MOHAMMED HASNAOUI

In this work, we present a numerical study of mixed convection coupled with radiation in an inclined channel with an aspect ratio B = L'/H' = 10, and discreetly heated from one side. Convective, radiative and total Nusselt numbers, evaluated on the heated wall of the channel, are presented for different combinations of the governing parameters, namely, the surface emissivity (0 < \varepsilon < 1), the Reynolds number (10 < Re < 50), the inclination of the channel with respect to the horizontal surface (0o< \theta < 90o) and the Rayleigh number (Ra = 105). Flow and temperature fields are produced for various combinations of the governing parameters. The results obtained show that the flow structure is significantly altered by radiation which contributes to reduce or enhance the number of the solutions obtained.