Abstract: Monitoring the part quality variation is essential to avoid defects and resource waste for green manufacturing achievement. However, it is difficult to obtain accurate images, vibration, pressure distribution, and other data for the accurate monitoring of the forming quality of stamping parts due to the closed mold and noisy production environment. Existing efforts indicated that the part thickness variation ratio varies quantitatively with process energy, which is the accumulation of punch force over the stamping depth, and it is easy to collect and anti-interference. In this context, a stamping process energy map is proposed to characterize the thickness variation ratio by color and its intensity. The stamping depth and process energy are set as the horizontal and vertical coordinates of the map, respectively. A data interpolation technique is applied to interpolate the measured thickness variation ratio data located in the map. Considering the limitation of finite measurement data on the accuracy of interpolation data, a data spatial blending strategy that weights and blends the interpolated and simulated thickness variation ratio data to fill and color the map followed by the quality zone division according to the threshold curve of thickness variation ratio. To validate the effectiveness, the map was applied to form a downscaling part of a car door. The mean absolute percentage error of the monitored thickness variation ratio was within 5%. The crack and wrinkle identification accuracy is up to 90.63%. The results of applying the map to stamping process control showed a 14.56% reduction in the maximum thinning ratio of the part, which effectively prevents cracking. The proposed stamping process energy map assisted in accurate part quality monitoring and quality improvement in stamping.

Key words: process energy, forming quality, monitoring map, data interpolation, data spatial blending