Numerical Analysis of the Deformation of a Shearing Machine Tool under Excessive Blade Clearance

Guillotine shearing machines for metal sheet may be inadvertently operated at increased blade clearance. Typical cases were studied using commercially available finite element software with an explicit solver. Loads causing elastic deformation to the machine structure arise from plastic deformation of the sheet metal being processed, its behavior being modelled by modified Johnson-Cook law. Excessive clearance was found to overload the machine considerably compared to normal clearance, owing to considerable lateral forces. As a result, the guillotine and much less so the base of the machine, undergo oscillatory deformation and the sheet is partly sheared and mostly bent. Such analysis helps the designer understand structural issues of the machine tool in extreme situations and modify the design appropriately.