An investigation of the measurement, fixturing, and trimming of large sheet metal parts

Abstract

Stretchformed sheet metal part production offers many challenges in process improvement such as increasing flexibility and part accuracy while decreasing cost and cycle time. The Reconfigurable Tooling for Flexible Fabrication (RTFF) project addresses these issues. This thesis investigates the measurement, fixturing, and trimming of large sheet metal parts. The objective of the thesis is to first present the current and alternative methods of three-dimensional measurement, fixturing, and trimming, especially for the RTFF project. Then, recommendations on the appropriate technology depending on the desired outcome can be made. Research show there are many potential technological changes that can be made to improve these current operations that encompass the sheet metal forming process. Three-dimensional shape measurement is investigated in detail. The current technologies are able to measure large sheet metal parts but have many disadvantages. A promising method of three-dimensional shape measurement is being researched and developed using laser speckle wavelength decorrelation. This method is still in development but initial results show that this method will decrease measurement time, decrease the amount of precision hardware needed, and decouple accuracy with the range of the object. Many of these factors are disadvantages of current measurement systems. A critical component of the promising measurement system is a precision linear actuator. A proposed design, consisting of cascaded solenoids and mechanical stops, is evaluated and shown to be unacceptable since commercial linear actuators perform the function more accurately and for lower cost.