Abstract
The quality of a bend is determined by the accuracy and consistency of the angle along the length of the part. This accuracy is directly related to the penetration of the tool in the die. Small variations in tool penetration can cause relatively large changes in bend angle. Such variations are caused by changes in the repeatability of the tool stopping point, by deflections of the press brake beams and by distortions of the tooling. Earlier studies [Int. J. Mech. Sci. 22 (1980) 583; J. Mater. Process. Technol. 35 (1992) 129; Precision bending of sheet metal, Master’s Thesis, University of Twente, 1992; A finite element simulation of free bending, in: Proceedings of the Second International Sheet Metal Conference, SheMet’94, University of Ulster, 1994, pp. 201–211] on finite element modelling of the air bending process assume that the tooling is perfectly rigid. The present 3D finite element model of press brake air bending tools allows calculation of elastic distortions in typical tools and relates the distortion to the accuracy of the formed part. The finite element model has been validated by experiments conducted on a commercial press brake. Some suggestions are made for improvements to the direct and cross stiffness of the tools which should lead to improved alignment of the tool and die and, in turn, to improved product accuracy.
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