ON THE MECHANICS OF GUILLOTINING DUCTILE METALS

Guillotining is the cropping of offcuts from plates using an inclined blade and the action is a steady-state composite of the actions occurring progressively in orthogonal bar shearing. Deformation patterns under the blade are discussed and forces, displacements and work inputs are investigated in terms of rigid-plastic fracture mechanics. The major work inputs concern shear and fracture in the plane of the cut face, and bending of the offcut to the inclination of the blade; other work inputs (e. g. for offcut twist and friction) may be neglected. Simple relations for cropping force versus offcut width are derived and confirmed by experiment. The effective fracture toughness (including work of flow) in the plane of cut, and the flow stress of the material may be determined from a simple linear plot of guillotining force versus offcut overhang width.