Spectral selective and difference imaging laser triangulation measurement system for on line measurement of large hot workpieces in precision open die forging

This paper presents the development of a measuring system for on line measurement of large hot workpieces in precision open die forging. The major advantage of the system is in achieving more accurate final dimensions of workpieces, reduction of finish allowance and reduced losses of workpiece material due to additional milling. Workpiece cross section is measured based on laser triangulation principle. A novelty in the developed measuring system is in avoiding light interferences from a hot glowing workpiece and workshop environment based on operation in green light spectrum and the use of difference imaging principle supported by laser switching. Workpiece dimensions are determined from the geometry primitives interpolated to the measured cross section. Measuring uncertainty, spatial resolution and environmental disturbances are analysed.