Straight tube piece for manufacturing gutter drain bend for gutter pipe, has overlapping area bent in fold portion, so that portion of overlapping area is covered by metal sheet material layers in outer and inner sides of hollow cylinder

摘要

The tube piece (1) has a welded or adhesive bond (4) provided in an overlapping area of opposite bent longitudinal edge portions (2, 3) of planar metal sheet material from which the tube piece is manufactured. The tube piece is made in a closed hollow cylindrical shape such that opposite bent longitudinal edge portions overlap each other in a longitudinal direction of the tube piece. The overlapping area is bent in a fold portion, so that a portion of the overlapping area is covered by metal sheet material layers in an outer side and an inner side of the hollow cylinder. The metal sheet material is coated with a thermosensitive material such as zinc or paint. The metal sheet material is a steel sheet material. Independent claims are also included for the following: (1) a method for manufacturing a tube piece from a metal sheet (2) a stretching bending apparatus for manufacturing a tube bend from a tube piece made of a metal sheet material (3) a method for manufacturing a tube bend from a straight tube piece made of a metal sheet material.