Bottenbockning

Bottenbockning is a term used in sheet metal forming to describe the forming of the bottom portion of a hollow or closed metal component by bending operations. The process aims to produce a bottom with a defined shape, such as a flat, domed, or flanged bottom, that can stand, seal, or contain contents. The term is commonly used in Swedish manufacturing literature and industry.

The method typically involves bending operations performed on a press brake or similar forming equipment using dedicated dies and punches. In some designs, the bottom is formed in conjunction with drawing or ironing stages to create a closed or semi-closed bottom. The exact geometry depends on the product requirements and may include a bottom edge that is flange-formed to join with side walls or a fully rounded bottom achieved through stepped bending sequences.

Materials and design considerations include material type (such as steel, stainless steel, or aluminum), thickness, and the required bend radii relative to thickness. Ductility and grain direction influence formability, and springback can affect final geometry. Proper lubrication, tool design, and controlled forming speed are important to minimize wrinkling, cracking, or thinning at the bottom.

Quality and inspection focus on bottom geometry accuracy, including roundness, flatness, and concentricity with the component, as well as integrity tests for leaks or seam strength in assembled parts. Bottenbockning is a specialized operation often integrated with the broader sheet metal fabrication process, including bending, drawing, and assembly, depending on the product design.

See also: sheet metal forming, bending, flanging, deep drawing.