Method for machining edges of steel sheet hole section of e.g. damaged hoppers of brass instrument, in plumber area, involves tapping steel sheet with counterpart, where edge of hole section is flanged and/or bent upward and widened

摘要

The method involves threading a hole section that is machined on a conical counterpart, where a steel sheet is wedged and completely filled out by the conical counterpart. A ring is pulled over the conical counterpart, where ring is made of steel. The steel sheet is tapped with the counterpart. An edge of the hole section is flanged and/or drawn up and/or bent upward and widened. The ring is held at its outer side with both hands by a person in charge and pulled from above over the conical counterpart. An upper end of the conical counterpart is provided in an opening of the ring. Independent claims are also included for the following: (1) a conical counterpart consisting of cast steel (2) a ring is made of steel.