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Tool wear monitoring in face milling

University of British Columbia

The purpose of this thesis is to investigate tool wear monitoring using Fourier Series simulation of steady state cutting forces. These simulations show that mean and fundamental values are all that is required to accurately predict immersion and tool wear (high frequency terms are ignored). It is found that the ratio of the magnitude of the fundamental values of force over the quasi-mean resultant force are insensitive to wear, while the same ratio is found to change markedly with immersion. Due to the nature of wear and different cutting conditions, two different wear identification methods are proposed. The first type of wear is chipping of the primary edge; the ratio of quasi-mean resultant force over mean torque gives the necessary indication without being affected by normal wear. The second type of wear studied is the normal wear band, where the axial force, F[formula omitted], (which was modelled using equivalent chip thickness, h[formula omitted], and equivalent approach angle,[formula omitted]) is found to be useful in the identification of this type of wear. The mean value of F[formula omitted] over the mean value of torque gives information about the state of normal wear while being insensitive to chipping. Work on an insitu sensor is also reported. Preliminary investigation shows that a deposit comprising a hybrid resistor on the flank face of a throw-away insert has the potential to monitor wear due to the permanent increase in resistance of the deposit as cutting proceeds. A U.S. patent has been obtained for this idea.

Text

2010-11-16

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http://hdl.handle.net/2429/29973

Mechanical Engineering

University of British Columbia

Graduate