Patent ID: 7412865

Claim:
A method of preparing a planar sheet of material for bending along a bend line comprising the steps of: providing a plurality of punch blades, each elongated in cross section, the cross section having a length and width and a die block having a plurality of elongated recesses for cooperating with the elongated punch blades; inserting the punch blades into a punch blade block configured to cooperate with the die block so that the length of each of the elongated punch blade is aligned along a line; forming a plurality of elongated displacement in the thickness direction of the sheet of material corresponding in number to the number and shape of the elongated punch blades, each elongated displacement having a length and width, by engaging the sheet of material between the elongated punch blades and elongated recesses so that each elongated displacement is sheared at least along its length from the planar sheet while leaving a transition zone of non-sheared material connecting a portion of each elongated displacement along its length with the planar sheet of material, each displacements including a planar flat zone, each planar flat zone spaced from the sheet of material and oriented substantially parallel to the planar sheet of material with the sheared portion of the periphery of the flat zone extending along and adjacent to the bend line and the transition zone spaced from the bend line.