Cap Welding Guidance and Inspection
3D machine vision guides and inspects cap welds at the assembly stage
During cell assembly, a cap is guided to the battery can’s cover, and the corners where the cap and can meet each other are welded shut. The poles are welded to two terminals on the backside of the cap, and the wound cell sheets are put inside of the can. Though this process can be done manually, a 3D laser displacement sensor and industrial cameras can help locate the welded area and inspect the weld quality using very high-speed geometric pattern-matching. A Cognex 3D laser displacement sensor measures the welds where the positive and negative poles are joined together, as well as where the poles are joined to the caps, and where the corners of the can and cap meet each other.
Pre-Welding Cap Guidance
Cognex’s PatMax software locates the targeted area for 3D inspection. The laser displacement sensor measures the height difference between the top cap and the battery can’s edge to ensure they are close enough. If the parts are level and positioned corrected, the CIC cameras guide the welding machine along a series of selected points for spot- or point-welding. This is a temporary step, before the parts are fully sealed at the next welding station.
At the second station, another 3D sensor inspects the welded edges or corners where the can and the cap meet to make sure they are fully sealed and free of defects, like bumps or sunken or exploded areas. If the edges pass inspection, the battery can is safe to fill with electrolyte fluid through a small hole before being fully welded shut.