A computer implemented method for positioning of a blank A and a blank B in a flat strip having a rectangular shape and extending generally in a longitudinal direction L and over a limited width in a transverse direction T, the lowest point of blank B being offset in the transverse direction by an offset dy compared to the lowest point of blank A, the method comprising of the following steps:
- providing a X, Y coordinate system parallel to L, T, where blank A is positioned in the X, Y coordinate system, wherein a furthest left point of blank A is located at X=0, wherein a lowest point of blank A is located at Y=0 and blank B is positioned, wherein a furthest left point of blank B is located at X=0 and a lowest point of blank B is located at Y=dy;
- providing a numerical representation of a contour of blank A and blank B in the X, Y coordinate system comprising discrete sets of vertices {A1, . . . , AP} and {B1, . . . , Bq}, p and q being integers greater than or equal to 3, the vertices being joined by straight edges;
- computing for each vertex Ai a distance dAiA being defined as a difference between a largest X value taken by the contour of blank A and a smallest X value taken by the contour of blank A at the Y value of vertex Ai and calculating a largest inner transverse distance dAA defined as the maximum value of all dAiA;
- computing for each vertex Bi a distance dBiB being defined as a difference between a largest X value taken by the contour of blank B and a smallest X value taken by the contour of blank B at the Y value of vertex Bi and calculating a largest inner transverse distance dBB defined as the maximum value of all dBiB;
- computing for each vertex Ai located at a Y value wherein at least one point of the contour of blank B is present oriented distances dAiB and dBAi defined respectively as a difference between a the X value taken by the contour of blank B and the X value taken by the contour of blank A at the Y value of vertex Ai and as a difference between the smallest X value taken by the contour of blank A and the smallest X value taken by the contour of blank B at the Y value of vertex Ai;
- computing for each vertex Bi located at a Y value for which at least one point of the contour of blank A is present oriented distances dABi and dBiA defined respectively as a difference between the largest X value taken by the contour of blank B and the smallest X value taken by the contour of blank A at the Y value of vertex Bi and as a difference between the largest X value taken by the contour of blank A and the smallest X value taken by the contour of blank B at the Y value of vertex Bi;
- computing an oriented distance dAB defined as a maximum value of all dAiB and dABI values, and computing an oriented distance dBA defined as a maximum value of all dBiA and dBAI values;
- Δ1 being defined as a pitch in the longitudinal direction between a left extremity of the A blank and the left extremity of its right-hand neighboring B blank, setting Δ1 to a value dBA;
- Δ2 being defined as a pitch between the left extremity of the B blank and a left extremity of its right-hand neighboring A blank, setting Δ2 to dBA if dAB+dBA≥dAA and dAB+dBA≥dBB, setting Δ2 to dAA−dBA if dAB+dBA<dAA and dAA≥dBB, setting Δ2 to dBB−dBA if dAB+dBA<dBB and dBB>dAA;
- and
- positioning a first blank A in the strip, positioning a first blank B with a transverse offset of dy and a longitudinal offset of Δ1 compared to the first blank A, positioning a following blank A in transversal alignment with the first blank A and with a longitudinal offset of Δ2 towards the first blank B and repeating the pattern along the strip as far as the strip extends longitudinally.