Method to manufacture box sealed at base and side walls from bent sheet metal section, for solar cooking box; involves perforating bend lines with small slits or holes filled with coating material

摘要

The method involves perforating the lines where the sheet metal section is to be bent with narrow slits or holes, which are so small that they are filled with inner or outer coating material, used to coat the box after its assembly. The filled slits or holes are sealed closed. Preferably the perforations are generated using a laser beam with a width less than 0.2 mm. The perforated lines are preferably separated along 75%-90% of their length. An Independent claim is included for a sheet metal section for making the box.