it 
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Godding, Robert 
  
PHOTOGRAMMETRIC MEASUREMENT TECHNIQUES 
FOR QUALITY CONTROL IN SHEET METAL FORMING 
Werner BOESEMANN', Robert GODDING', Holger HUETTE 
" Aicon 3D Systems, Germany 
info@aicon.de 
"University of Hanover, Germany 
Institute for Metal Forming and Metal Forming Machine Tools (IFUM) 
huette@ifum.uni-hannover.de 
Working Group 5.1 
KEY WORDS: Sheet metal forming; Quality; Springback; Visioplasticity; Optical 3D measurement; Online-System. 
ABSTRACT 
Within the Brite/EuRam project “DIGIMAN” a new optical measuring system for the assessment of sheet metal 
components in terms of shape accuracy and strain distribution has been developed. Based on the photogrammetrically 
measured geometric parameters of the object the system detects deviations from the desired geometry caused by 
springback and allows the strain analysis within critical stamping part areas. Such a system was installed at the Institute 
for Metal Forming and Metal Forming Machine Tools (IFUM) of the University of Hanover. Further systems will be 
implemented at different car manufactures and producers of sheet metal stamping parts. Typical applications of 
photogrammetric measurement techniques in sheet metal forming are described in the following paper. 
1 INTRODUCTION 
Sheet metal forming is one of the most efficient and most economic production processes for mass production of 
automotive components as well as household articles. Forced by the progressive automation and consistent 
rationalization, the use of new sheet materials as well as innovations in the press and tool technologies a considerable 
increase of productivity was obtained in the press shops within the last decades. The intensifying global economical 
competition as well as the growing consumer demands concerning product quality and costs will accelerate this trend. 
The demands of car customers are mainly the car design, safety, comfort, engine performance, fuel consumption and 
especially the aesthetic appearance of the visible parts. Many sheet metal components, as example outer body panels, 
have an aesthetic function, so that deviations from the desired geometry cannot be accepted. These components require 
an even curvature of the surface to achieve smooth light reflection and any surface defects are of essential significance 
and quality control has to focus on them. Assembled outer body panels should have close tolerances. The historical 
development of the tolerances demanded by the automotive industry is illustrated in Figure 1. 
tolerances 
stamping subassembly body-in-white 
  
  
  
  
  
  
  
  
  
  
  
component 
+0.75 210 
past | +05 7 9 
x 
«0.5 «0.65 :g 
$ 
2 
40.2 40.25 40.33 8 
   
future 
  
Figure 1: Development of the tolerances in the automotive industry 
The growing quality standards especially require optimized processes and efficient methods of quality control. The 
main objective is a 100%-in-process quality control in press shops. 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000. 291