An Investigation on Temperature Measurements for Machining of Titanium Alloy using IR Imager with Physics-based Reconstruction

In general, the physical field in a domain can be uniquely determined from appropriate physical laws by its field conditions on its boundary surfaces. In machining, the ability to measure the tool surface temperature distribution is highly desirable as it provides an essential basis to reconstruct the thermal model for monitoring tool and workpiece conditions, particularly when machining hard to machine materials (such as titanium alloy that exhibits excellent mechanical properties and corrosion resistance). Because of the extremely high temperature gradient within a very small area, the need for developing an effective non-contact measurement technique has been a well-recognized problem. In the context of dry lathe-turning of titanium alloy, this paper presents a method based on non-contact infrared images to reconstruct the temperature field of the tool insert. Unlike traditional methods that base on limited thermocouple measurements or direct reading of absolute temperature from infrared images, the method presented here utilizes physical laws and heat transfer properties (temperature contours and their gradients) to identify thermal discontinuities, separate chips from the tool insert and reconstruct the obtruded tool temperature field.