Subject: A Methodology for In-process Quality Monitoring of Manufacturing Processes
Abstract: Mechanical impedance detected at the input port (Zmi) of a mechanical system contains rich information characterizing the health condition and output quality of the system. Although useful for accurate monitoring, Zmi was hardly utilizable as monitoring signature because its detection 1) required both force and motion sensors be installed in limited space and/or unfriendly environment for being in-situ, and 2) demanded straight-forward and speedy digital signal processing for being real-time.
A manufacturing system normally contains a few subsystems in-series driven by an electro-mechanical actuator at the upstream terminal to do work on the work-piece at the downstream terminal. When health problems occur in these subsystems and lead to poor manufacturing quality, the Zmi at the output port of the actuator (which is also the input port of the processing system) changes. This change naturally leads to variation of the electrical impedance at the input port (Zei) of the actuator. If the dynamic system behavior between Zmi and Zei, or, “transduction matrix” as introduced in this work, of the given actuator is made known, the aimed quality monitoring function can be achieved by detecting Zei without involving force and motion sensors.
In this talk, the definition and calibration techniques of transduction matrix of actuators is introduced. To make the quality monitoring simple, real-time and automated, proper selection of techniques for evaluating impedance from signals and recognizing patterns is also briefly discussed. A few examples are presented to demonstrate the usefulness and simplicity of the proposed method in in-process monitoring of processing quality. It is also noted that, by curve fitting the obtained Zmi, the method turns out to be a useful tool to investigate and model the working mechanism of certain manufacturing processes.
TIME: At 3:30pm, August 22nd, 2011
PLACE: The meeting room on the fourth floor of the Mechanical and Electrical Building in Yuquan campus
CONTACTER: Professor Ju Bingfeng
Phone: 87951730