The analysis of bottom forming process for hybrid heating device

The author presents an unusual method of bottom forming for various purposes including water heaters or pressure equipment. This method allowed to manufacture the bottom of stainless steel for a shape according to the DIN standard which determines the most advantageous bottom cross section in terms of working pressure loading. The author checked validity of the method in a numerical and experimental way generating a tool designed to produce bottoms of specified geometry. Many problems were encountered during design and production of parts, especially concerning excessive sheet wrinkling in a large area of the part. The experiment showed that lack of experience and numerical analysis in design of such elements would cause obtaining high wrinkled parts. As a result, it would make it impossible to assemble them with the cylindrical part. The author presented and compared two forming methods for spherical and parabolic objects, experimentally confirming the validity of selection of the sheet reversing method with adequate pressure force. The applied method produces parts in one drawing operation and in the following operation that is based on laser or water cutting to obtain round blank.