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3D Geometry Detection by Sparse Ultrasonic Transducer Arrays for Sheet Metal Hydroforming
Author(s) -
Meier Horst,
Knoll Patrick,
Ermert Helmut,
KeitmannCurdes Oliver
Publication year - 2005
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.200506109
Subject(s) - hydroforming , transducer , ultrasonic sensor , acoustics , sheet metal , materials science , process (computing) , pressure sensor , transmitter , mechanical engineering , computer science , engineering , tube (container) , composite material , electrical engineering , physics , channel (broadcasting) , operating system
While most of the research on fluid forming processes and especially on sheet metal hydroforming is based on numerical analysis, an experimental approach is presented to measure the geometrical form of a sheet metal during the hydroforming process. The ambient conditions inside the pressure chamber like high pressurized liquid media inside a steel surrounding led to the usage of an acoustical based system. The whole system comprises just a small number of ultrasonic transducers, used alternating as transmitter or receiver. Every transducer operates as a transmitter after each other while the remaining ones are receiving simultaneously. The main part of this work concentrates on different strategies for the reconstruction of the sheet metal contour out of the ultrasonic data. Therefore, two different strategies are discussed and compared. The pixel driven SAFT‐algorithm (synthetic aperture focusing technique) has been chosen and solutions for major improvements are given. The technical system and also the algorithms were tested with a specially designed test rig under normal ambient conditions with various geometrical sheet forms. The results show that geometries of about 200 by 200 mm 2 can be detected by only 10 by 10 transducers. Especially for simple geometries with slight slopes the reconstruction accuracy is already quite good. Finally the influence of the pressure and the temperature of the working media on the accuracy of the reconstructed data is explained.