An ultrasonic testing plant is described that is intended for the inspection of heavy plate to detect internal defects and, additionally, surface defects in the plate head and tail regions. The plant is installed within the flow of production, i. e. upstream of the trimming shears above the roller table at a portal. With its special-design probe holders with running-water gap coupling, the plant is able to inspect hot plates with a temperature of upto 300°C, the plate thickness inspected ranging between 5 and maximally 150 mm. The overall plant is of completely modular design. For plate widths of at least 1.10 m upto 4.40 m, upto 4 inspection carriages with 8 oscillating TR probes each are applied for one complete ultrasonic inspection, with the probes in a two-row staggered arrangement. Each inspection carriage inspects a longitudinal plate strip of 1 m width with a transport speed of maximally 1 m/s. The surface inspection plant is complemented by an edge zone testing plant consisting of three inspection carriages arranged in front of and behind the surface inspection plant. This edge zone testing plant allows to acquire the longitudinal plate edges as well as the head and tail regions of the plate. The inspection of the head and tail regions includes, the addition to an internal defect detection, the detection of surface defects on the plate top and bottom surface performed by angle beam probes which are moved along the plate width. Each edge zone inspection carriage covers a width of 100 mm with 9 TR probes each. The overall plant is controlled fully automatically by means of corresponding sensors. Each inspection carriage for surface and edge zone inspection is equipped with an 8 (16)-channel ultrasonic electronics unit called AMUS using the modern ALOK technology as well as with an electronics unit to process ultrasonic data. The processed data are transmitted to a higher ranking analysis computer where they are sorted and processed further in compliance with the preset inspection specification. The resulting plate analysis is printed in an inspection protocol and submitted as summarized inspection output to the central computer of the rolling mill. In addition to the defects protocol for the plate inspected, an averaged plate thickness protocol of all test shots is generated.
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