Abstracts Category : Other

Experimental investigation and numerical analysis of heat transfer in multi-layer CVD coated carbide tools

by Philip Joseph

Earlier work done on the thermal constriction phenomenon that assumed constant material thermal conductivities has been improved upon by incorporating temperature dependent conductivities. When temperature dependent thermal conductivities were used in the model it was observed that maximum conductance is not necessarily achieved at the maximum contact pressure. Furthermore, a Matlab program that generates thermal constriction data of any given coated tool (3 coating layers + 1 substrate layer) for quick and easy input into a FEbased simulation of the machining process was created.Cutting tests and thermal experiments were carried out on nine different multilayered coated tools and their results are presented and discussed. Measurements were made of the effects of the composition of the coating material (AL2O3, Ti(C,N), TiN) as well as its thickness, texture, crystal orientation and coating architecture. To complement the experimental data, FE Simulations were carried out using DEFORM 3D to validate the thermal constriction model. The results of this exercise is presented and discussed as well.A novel method for determining the convective heat transfer from a rotating workpiece in dry turning processes without the need for thermocouple insertion or slip rings was developed. An attempt has been made to develop a similar methodology for determining the convective heat transfer of a rotating workpiece under coolant flow from nozzle. Des travaux antrieurs effectus sur le phnomne de constriction thermique qui suppose une conductivit thermique matrielle constante a t amlior en incorporant conductivits dpendant de la temprature. Quand la conductivit thermique dpendant de la temprature ont t utilises dans le modle, il a t observ que la conductance maximale ne soit pas ncessairement ralise la pression de contact maximale. En outre, un programme Matlab qui gnre des donnes de rtrcissement thermique de tout outil donn revtu (couche 3 couches de revtement de substrat + 1) pour la saisie rapide et facile dans une simulation du procd dusinage base de fer a t ralis.Essais de coupe et des expriences thermiques ont t raliss sur neuf outils revtus multicouches diffrents et leurs rsultats sont prsents et discuts. Les mesures ont t faites sur les effets de la composition du matriau de revtement (Al2O3, Ti (C, N), TiN), ainsi que son paisseur, la texture, lorientation cristalline et de larchitecture de revtement. Pour complter les donnes exprimentales, FE Des simulations ont t effectues en utilisant DEFORM 3D pour valider le modle de constriction thermique. Les rsultats de cet exercice sont prsents et discutes.Une nouvelle mthode pour la dtermination du transfert de chaleur par convection partir dune pice en rotation dans les procds de retournement sec sans quil soit ncessaire pour linsertion dun thermocouple ou danneaux de glissement a t dvelopp. Une tentative a t faite pour dvelopper une mthodologie similaire pour dterminer leAdvisors/Committee Members: Mahmoud Helmi Attia (Supervisor1), Peter Henry Radziszewski (Supervisor2).