Monitoring the forming dimensions of components produced by arc-directed energy deposition based on a molten pool’s geometric characteristics

A deposition size monitoring method based on a molten pool’s geometric characteristics, including image calibration, contour extraction, contour coordinate calculation, and deposition size modeling, is established in this study to observe the real-time size of components formed by arc-directed energy deposition (ADED). Image calibration was first performed using the molten pool’s imaging transformation matrix to accurately match the image’s pixels to the actual spatial position. Next, an adaptive threshold segmentation algorithm was applied to extract the contours of the calibrated molten pool’s images. The contour was further completed using breakpoint coordinates and their gradient information. The minimum bounding rectangle algorithm was used to fit the contour coordinates for determining the width and height of a single-pass deposition. A mathematical multi-pass and multi-layer depositional size model was created via the parabolic model and the equal volume algorithm for realizing the deposition size monitoring based on the molten pool images. Finally, the rocket engine shell was manufactured using ADED, and the depositional forming size was observed in real time. The overall average size deviation of the component was within ±2.41 mm, suggesting a high forming accuracy.