Sharp bending of Sheet Metal with Indentation of V- Shaped Punch

摘要

Recently bent parts of sheet metal generallyrequire sharp bend corners from the point of view of presentinga fine appearance. For sharp bending, there is a method ofcutting the part of the sheet in question into a V-groove formbefore bending. However, this method is problematic in that thestrength of the bent part is reduced and V-groove cuttingrequires much time. To resolve such problems, the present studyexamined the method of first forming the V-groove by pressinga V-shaped punch onto the sheet before bending. The features ofthis method are that the strength is improved through workhardening by punch indentation, that a press machine is used forgroove formation so that the work time is reduced, and that noexclusive cutting machine is required. Sharpness of the bentcorner is nearly the' same as that of the groove cut material, andthe strength of the bent part is improved to about 1.2~1.4 timesthat of the groove cut sheet. For groove formation, a CNC turretpunch press can also be used, and the bending radius of theobtained product is nearly equal to that of the groove indentationsheet by means of a usual punch.