Steel is the most important material in vehicle and machinery construction. Large quantities of offcuts and scraps are left over from rolling and milling crude steel into strip steel. New radar from Fraunhofer researchers measures the width of the strip during fabrication to an accuracy of micrometers and helps to minimize scrap. This permits the rolling facility to self-adjust so that less scrap is produced with considerable savings in costs.
Two radar sensors mounted at the side of the rolls measure the distance to the edge of the steel. In principle, the system can be compared with echo-locating by bats. The ultrasound signals that bats emit are reflected back by mice, branches, wires, and mosquitoes like echoes. Bats listen to the echoes from things located in front of them and distinguish prey from obstacles.
"Our radar sends out continuous electromagnetic signals that are reflected by the right and left edges of the strip. The transmitted and received signals are then compared to each other with the help of numeric algorithms. The width of the sheet can be calculated from this comparison," says Prof. Nils Pohl, scientist and head of department at FHR, in explaining the principle of how the system operates. The radar that determines distances of up to several meters with a precision of just a few micrometers, also measures very quickly - 5000 times a second. Silicon chips developed in-house make these values possible.