Traction bending

Traction bending apparatus for bending workpieces, comprising:

• a stationary die support for mounting a die adjacent a first end thereof and having a second end remote from said first end, and an intermediate section between said first and second ends;
• at least a first control arm pivotally mounted at a first pivot axis to said die support at a first portion thereof, adjacent said die support second end;
• at least a first linear actuator pivotally connected to said first control arm at a second pivot axis and pivotally connected to said die support adjacent said die support second end at a third pivot axis, said first linear actuator providing powered pivoting of said control arm about said first pivot axis;
• at least a first traction arm pivotally mounted at a fourth pivot axis to said first control arm at a second portion of said first control arm, remote from said first portion of said first control arm, said fourth pivot axis adjacent but spaced from said second pivot axis;
• a workpiece engaging member associated with said first traction arm remote from said fourth pivot axis;
• and
• at least a second linear actuator pivotally connected to said first traction arm at a fifth pivot axis adjacent but spaced from said fourth pivot axis, and pivotally connected to said intermediate section of said die support at a sixth pivot axis, said second linear actuator providing powered pivoting of said first traction arm about said fourth pivot axis.

A method of effecting bending of a workpiece using a stationary die, clamping flanges at the stationary die, and powered workpiece engaging elements, comprising the steps of substantially sequentially:

• (a) bringing a workpiece into contact with the stationary die;
• (b) effecting direct linear movement of the clamping flanges to provide constant pressure clamping of the workpiece at the die to control thickness and wrinkling of the workpiece;
• (c) swinging the workpiece engaging elements into operative abutting contact with the workpiece at the points on the workpiece where bending will occur, and applying pressure to the workpiece with the workpiece engaging elements;
• (d) while continuing to maintain pressure on the workpiece with the workpiece engaging elements, moving at least one of the workpiece engaging elements with respect to the stationary die to effect smooth bending of the workpiece while continuing operative abutting contact with the workpiece;
• and
• (e) after desired bending of the workpiece, swinging the workpiece engaging elements out of abutting contact with the workpiece, and releasing clamping of the workpiece.

A method of effecting bending of a workpiece using a stationary die, clamping flanges at the stationary die, and powered workpiece engaging elements, comprising the steps of substantially sequentially:

• (a) bringing a workpiece into contact with the stationary die;
• (b) effecting direct linear movement of the clamping flanges to provide constant pressure clamping of the workpiece at the die to control thickness and wrinkling of the workpiece;
• (c) swinging the workpiece engaging elements into operative abutting contact with the workpiece, and applying pressure to the workpiece with the workpiece engaging elements;
• (d) while continuing to maintain pressure on the workpiece with the workpiece engaging elements, moving at least one of the workpiece enraging elements with respect to the stationary die to effect smooth bending of the workpiece while continuing operative abutting contact with the workpiece;
• (e) after desired bending of the workpiece, swinging the workpiece engaging elements out of abutting contact with the workpiece, and releasing clamping of the workpiece;
• and
• after step (e), effecting powered linear movement of the workpiece away from the die.