Bending apparatus and method of bending a metal object

A method of manufacturing bent metal tubes comprising:

• placing a first metal tube in a rotary draw bender;
• bending a first portion of the first metal tube to a first predetermined bend coordinate using a first applied force;
• wherein the first predetermined bend coordinate is based at least in part on expected springback of the first metal tube to a final bend position of the first portion;
• releasing the first applied force on the first metal tube to allow actual springback thereof;
• after said releasing, without moving the first metal tube relative to the rotary draw bender except movement due to the actual springback, measuring an actual bend coordinate of the first portion resulting from the first applied force and actual springback of the first metal tube;
• calculating a bend correction factor based at least in part on the measured actual bend coordinate;
• rebending the first portion of the first metal tube to a revised bend coordinate using a second applied force;
• wherein the revised bend coordinate is based at least in part on the calculated bend correction factor;
• releasing the second applied force to allow actual springback of the first metal tube again;
• after said releasing the second applied force, measuring a new actual bend coordinate of the first portion resulting from the second applied force and actual springback of the first metal tube after the releasing of the second applied force;
• and
• bending a second portion of the first metal tube to another bend coordinate based at least in part on the calculated bend correction factor.

An apparatus for bending metal objects, comprising:

• a stationary base;
• a measuring device secured to the stationary base;
• a plurality of dies configured to bend metal objects including a rotatable bend die, and a clamp die rigidly securable to the rotatable bend die, and a pressure die movable with respect to the rotatable bend die;
• wherein the measuring device is operable to measure actual bend coordinates of metal objects bent by the dies without movement of the measuring device relative to the stationary base and without post-bending movement of the metal objects relative to the rotary draw bender except movement due to springback;
• and
• a controller operatively connected to the dies, the base and the measuring device and configured to control the dies to bend the metal objects at least partly based on the measured bend coordinates provided by the measuring device.