Title

Embedded Sensing and Characterization of Contact Pressure Distributions for Advanced Stamping Processing Monitoring

Date of Completion

January 2011

Keywords

Engineering, Mechanical

Degree

Ph.D.

Abstract

This research proposes a new sensing methodology for measuring the contact pressure distribution (CPD) on tool-workpiece interfaces in sheet metal stamping processes. Stamping refers to the forming of sheet metal parts through material flow and strain induced by mechanical loading. Conventional tool and sensor configurations used in the stamping process monitor and control the process only through secondary observable parameters such as net tool force. It is hypothesized that knowledge of the contact pressure distribution across the interface between the tool and workpiece will provide insight into stamping process and improve the observability and controllability of this manufacturing process by accessing the previously untapped potential of spatio-temporal domain information for describing the primary interaction. ^ This research presents an online sensing method that measures the in-process contact pressure distribution at the tool-workpiece interface through an array of dynamic force sensors embedded in the stamping tool. This provides a spatio-temporal record of the tool-workpiece interaction during the sheet metal deformation process which is valuable for die design optimization and tool wear monitoring. More importantly the proposed sensing method will enable process designers to better control the stamping process by providing feedback on the tool-workpiece interaction.^ There are several fundamental scientific and engineering issues that have been addressed in this work for realizing a robust measurement technique. These issues are classified as follows.^ Scientific Issues: Optimal sensor location selection through geometric and model based techniques, numeric reconstruction of spatially sparse measurements, formulation of data fusion techniques for model augmented pressure reconstruction, modeling of piezo-electric transducers under generalized electro-mechanical loading, and construction of stamping pressure and draw-in maps for the representation of stamping process dynamics.^ Engineering Issues: Characterization of tooling integrated sensors and contact interactions through experiments and empirical models, large scale experimental evaluation of tooling integrated sensing technology, design and characterization of a self energized wireless sensor.^ It is envisioned that the technology and methods presented in this work will add to the fundamental understanding of the stamping process dynamics and advance the state-of-art in sensing and data analysis for intelligent manufacturing. ^