The Investigation of cutting tool behaviour in tool life and the development of a real time tool breakage system


Thesis Type: Doctorate

Institution Of The Thesis: Bursa Uludağ University, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2001

Thesis Language: Turkish

Student: YAHYA IŞIK

Supervisor: Mustafa Cemal Çakır

Abstract:

The purpose of this research is to develop a tool condition monitoring and a real- time tool breakage detection system to be used in cutting processes. Tool behaviour was studied in four sections. Firstly an optimum experimental design to determine the coefficients of the extended Taylor’s Equation in machining is proposed. This technique allows the best set of machining parameters to be determined in order to estimate the coefficients of Taylor’s equation. Secondly the relationship betvveen cutting forces and tool wear rate has been investigated experimentally. The surface roughness has been identified as one of the most undesirable characteristic of the machining operations. Experiments were carried out to study how the surface roughness is affected from these cutting parameters in turning. The developed softvvare enables to determine the changes on the cutting forces and the tool wear and the surface roughness on the conditions of during the tool life. These changes were represented graphically. The performance of the system has been tested experimentally for certain machining conditions for a particular vvorkpiece and cutting tool material combination. The display allovvs the user to check the validity of the cutting force measurements and also gives a visual feed back on the current status of wear. HSS, WC, TiC+TıCN+TiN and TiC+AI2O3+TiN and TiAlN coated Carbide tools were used in the experiments as tool material. The tool breakage based on the characteristic variation of the cutting force and tool wear. The change of cutting force and tool wear can itself be a good indicator to detect the tool breakage. The tool breakage features were extracted from the decomposed signals. The predicting values are decided for the cutting conditions. The experimental results shovved that the system was succesful in predicting wear components and the tool breakage. Either an alarm is sent to the operatör or tool is changed automatically when the cutting tool edge is broken or the wear reaches a threshold limit. When the tool breakage and condition monitoring systems can used be effectively in the ındustriy, İt reduces the cost of production, increases qualıty and quantity of the production, stabılıty of machine tool and helps to analyse the cutting conditions.