Manufacturing method for upper die tool bit of U-shaped workpiece bending die

The invention discloses a manufacturing method for an upper die tool bit of a U-shaped workpiece bending die, belongs to the field of bending machines and solves the problem that high-quality U-shaped workpieces with different arc-end radiuses cannot be produced quickly by the conventional bending die. The die provided by the invention comprises an upper die and a lower die, wherein the upper die comprises an upper die clamping part, an upper die body and an upper die tool bit; the lower die comprises a lower die base and two lower die forming blocks; the upper die tool bit is connected with the upper die body through a bolt; a groove is formed in the upper surface of the lower die base; the two lower die forming blocks are symmetrically mounted on two sides of the groove in the upper surface of the lower die base respectively; adjusting cushion blocks are arranged between the inner wall of the groove and the lower die forming blocks; an arc-shaped groove is formed in the inner side of the upper surface of each lower die forming block; and a workpiece movement assisting column is arranged in each arc-shaped groove. The die provided by the invention is safe and reliable, can be adapted to production of U-shaped workpieces with different arc-end radiuses and is high in production speed and product quality.