Challenge details:

During the cut-to-length process, steel coils are cut into specific lengths. These cut sheets are then conveyed via a belt conveyor to the stacker unit, where they are stacked. The stack is subsequently transferred via chain conveyors to the crane lifting area. During this transfer, dents or scratches often develop on the bottom surface of the sheets (see Fig 1), which is unacceptable to the customer. These dents are detected manually at the packaging station, where the quality assurance inspector checks for them while the sheet stack is suspended by the crane, posing a safety risk.

Identifying the origin of these dents is challenging due to the presence of two chain conveyors. Currently, the issue is addressed by checking for chain looseness along the length of the sheet where dents are present or inspecting for any particle deposition on the chains that could be causing the defects. We are seeking a solution to detect and eliminate the occurrence of dents.