In-situ measurement based on prior calibration with analogist samples for laser cladding

摘要

Based on prior calibration with analogist samples, a system, consisting of a CCD camera, a frame grabber and a computer, is developed to in-situ measure the molten pool parameters during laser cladding. The signals captured by CCD vary with change in substrate or clad material, so that, in order to gain the true data of the molten pool parameters, calibration of the instrument must be performed for every set of substrate and clad materials. In this study, a new strategy for on-line acquisition of molten pool parameters is presented. Before measurement of the objective molten pool, cladding is performed to get some analogist samples of the same materials as those used to generate the objective molten pool. The width of a certain segment of the clad bead on the analogist sample is gauged to calibrate the CCD camera-grabbed image of the molten pool which has solidified to this segment of the clad bead. The pool width in the grabbed image can be confirmed to the gauged bead width times the scaling because the width of the clad bead segment must be equal to the width of the related pool. It is assured which type of area in the grabbed image is located on by the pool, and the CCD is calibrated for this set of substrate and clad materials. After calibration, the CCD system is applied to in-situ measure the molten pool parameters during laser cladding. In the presented experiments, the measured values agree well with the actual ones.