The bending of sheet metal in sheet metal processing should meet the following 5 basic requirements after bending.
(1) no significant elliptical deformation is allowed at the cross section of the bending point.
(2) the angle of bending is accurate.
(3) the outer surface of the bending surface should be smooth, smooth, without wrinkles and cracks.
(4) if the sand is bent, the internal sand should be thoroughly removed.
(5) if the joint of the pipe is along the axis, the joints should be placed in the neutral layer so as to avoid the deformation of the pipe.