A Hybrid Method Based on Macro–Micro Modeling and Infrared Imaging for Tool Temperature Reconstruction in Dry Turning

In metal cutting, the ability to model its tool temperature distribution is highly desirable, as it provides an effective means to monitor the tool and workpiece conditions, particularly when machining hard-to-machine materials that have a low heat conductivity. Because of the complex heat generation in the microscale tool-chip interface, the difficulty to infer its temperature distribution is a well-known problem. In the context of dry lathe turning, this paper presents a hybrid method that considers both the macroscale tool heat transfer and microscale machining mechanics to reconstruct the 3-D tool temperature field from nonobstructed infrared (IR) images. The microscale-mechanics model identifies the contact geometry and estimates the frictional heat input to determine the complete boundary conditions to solve the macroscale heat-transfer model for the steady-state 3-D temperature distribution that provides a basis for experimentally fitting the model by comparing the computed surface temperature with actual temperature measurements. Two sets of experimental results validating the reconstructed temperature on a customized orthogonal-cutting testbed with a high-resolution IR imager and evaluating the effectiveness of the hybrid method on a lathe-turning center are presented. The results demonstrate that with the hybrid macro-micro modeling, the 3-D steady-state temperature field of a typical commercial lathe tool insert can be accurately reconstructed from a relatively low-resolution IR image.