Automated U-Bolt Inspection System

Consolidated Metal Products has a unique cold-forming process to create U-bolts that makes themthe industry leader in U-bolt production. This process has a tendency to create cracks due to high residualstresses. The senior design team researched several methods of crack detection including ultrasonic, dyepenetrant, and visual camera inspection. The conventional ultrasonic method was tested by NDT systems inhouse and was shown to work with the curvature of the U-bolt. Fluorescent dye penetrant was tested byapplying the dye to the bolts with, and without cracks in them and then observed the difference in light valuesin and out of the cracks. Camera inspection was tested statistically by comparing light intensity values insideand out of crack areas on gathered images without the application of dye. After testing these methods, camerainspection was chosen through the use of a selection matrix. In The senior design, the team began withconstruction of a controlled lighting environment box for taking photographs of U-bolts. A Matlab code wasformed to compare light intensity values of bolt images and to work in unison with an Arduino to outputseparate signals for normal and defective U-Bolts. The Matlab code also automatically analyzed images takenby the camera. The Matlab code was then tested with sample bolts. Threshold light values were obtained tooptimize the system’s ability to detect cracks