Knowledge Bank

This thesis presents results from experiments involving novel sensing of the process, and numerical simulations of process mechanics to enable improved understanding of the mechanics of radial indentation during incremental profile forming (IPF). IPF allows the flexible manufacture of metallic tubular structures with cross-sectional profiles that vary along their length, but its geometric accuracy is limited by exclusive reliance upon machine control of the process. Precision of the resulting part geometry in IPF requires improved understanding of process mechanics, along with on-line sensing of the process, for improved process control. In this thesis, novel procedures for on-line sensing of part geometry during radial indentation and axial grooving, using laser triangulation sensors, are developed.
To address the aforementioned subjects, the first part of the research involved measurements that provided insights into the working mechanism and limitations of the sensors used to capture the profiles during or after indentation and grooving. As a tube was subjected to one of the two processes, two sensors measured its circumferential profile at the indentation point while the third sensor captured its longitudinal profile. The analysis of the sensor generated profiles yielded results that indicate that the sensors have limited optical access in regions where the geometry of the tube experiences big changes and in regions near the edge of the sensors' measuring range. Even so, the sensors have offered crucial information regarding the process of axial grooving. The processed data indicates that the process reaches a steady state starting in the middle of its run. Since the sensors can capture a section of the indenter geometry, which is known, the measured data also provided a way to measure sensor accuracy. This thesis will aim to gain an improved understanding of the geometry of deformation during radial indentation through finite element analysis. Simulations of single-indenter and multi-indenter radial indentation processes were done on ANSYS Workbench by using quarter-model symmetry. The analysis of the simulated profiles indicated that the current model needs to be improved because a comparison of flow curves between the current model and a previous model showed insufficiencies. The simulated and the experimental profiles were compared, and they showed general agreement, except in regions near the indent. Understanding of process attributes will aid improved understanding of other components of the IPF process such as axial grooving, thereby proving useful in designing the overall sensing strategy for effective part control in IPF.