Method and apparatus for bending steel rule

A method of manufacture of steel rule dies wherein a steel strip is fed into a machine by strip feeding means, whose operation comprises, in the following order:

• (a) inputting elasticity information describing the steel rule being used into a computation and control unit;
• (b) inputting information representing the shape desired to be fabricated into the computation and control unit;
• (c) calculating the location of the next bend to be made, the angle of said next bend, and the direction of said next bend, in the computation and control unit by use of a program which takes into account in its calculations the steel elasticity information and the shape information;
• (d) advancing said steel strip by driving means through a linear displacement encoding means which provides a linear encoding displacement signal which accurately locates a point on said steel strip throughout the travel of said steel strip;
• (e) gripping said steel strip firmly by gripping means, which has an input side, where said steel strip enters said gripping means, and an exit side, where said steel strip exits said gripping means, whereby said steel strip is gripped at said next bend location;
• (f) bending said steel strip, by bending means, at said exit side of said gripping means in the amount, and in the direction, calculated by said computation and control unit;
• (g) viewing the steel rule at the exit side of the gripping means by use of optical measuring means, thereby producing an electrical signal representative of the shape of the steel rule;
• (h) feeding said electrical signal back to the computation and control unit;
• (i) calculating the position, displacement, and direction of the next bend to be made, in the computation and control unit, taking into account said electrical signal, said steel elasticity information and said shape information;
• (j) repeating said operation at clause (d) of this claim, until the die has been completely formed;
• (k) withdrawing the bending means and gripping means from the steel rule;
• (m) moving the steel rule to the cutting location;
• and
• (l) cutting the steel rule by die cutting means at the last position calculated by the computation and control unit.

An apparatus for forming steel rule into a predetermined shape through a series of bending operations, comprising:

• control means for controlling operation of said apparatus, said control means including a memory for storing data for forming a predetermined shape including at least a table containing a desired deflection amount for each bending operation and a distance between bending operation;
• gripping means for gripping said steel rule under control of said control means so that a portion of said steel rule protrudes from an exit end of said gripping means;
• means for deflecting said protruding portion relative to the exit end of the gripping means by a calculated amount under control of said control means;
• means for feeding said steel rule to said gripper means in a longitudinal feed direction in amount determined by said control means;
• and
• optical means arranged to view said protruding portion and produce and supply to said control means a signal indicative of an actual shape of said protruding portion for each current bending operation;
• wherein said control means includes means for determining an actual deflection of said protruding portion from said signal and comparing aid actual deflection to the stored desired deflection for the current bending operation, and determining said calculated amount for a bending operation immediately subsequent to the current bending operation, said calculated amount being based on a stored desired deflection for said subsequent bending operation and a deviation in the current bending operation between the actual deflection and the desired deflection of the current bending operation.