Sheet metal elbow for drainage of rainwater to gutter is made of sheet metal and is made from longitudinal section of continuous pipe material whereby one side of sheet is coated and by mechanically connecting edges of sheet elbow is formed

摘要

The sheet metal elbow is the longitudinal section of continuous pipe material (2). Metal sheet is cut and at least one side is aluminum zinc coated. Then by mechanical connecting two opposite longitudinal edges, the sheet is converted into tube. After formation of pipe, pipe material is pulled. Thickness of sheet must be uniform and sheet is double grooved.