Patent ID: 7584637

Claim:
A method of bending a metal object comprising: applying force with a rotary draw bender to bend a first portion of a first metal object a first time to a predetermined bend coordinate; wherein the predetermined bend coordinate is based at least in part on expected springback of the first metal object to a final bend position; wherein the first metal object is a tube; releasing the force applied to the first metal object to allow actual springback; after said releasing, without moving the first metal object relative to the rotary draw bender except movement due to the actual springback, measuring a first actual bend coordinate on the first metal object resulting from the applied force and the actual springback; calculating a first bend correction factor based on the predetermined bend coordinate and the first measured actual bend coordinate; reapplying force to bend the first portion of the first metal object a second time to a first revised bend coordinate based at least in part on the calculated first bend correction factor; releasing the reapplied force from the first portion of the first metal object; applying force to bend a first portion of a second metal object a first time to the predetermined bend coordinate based in part on the expected springback; releasing the force applied to the second metal object to allow actual springback of the second metal object; after said releasing the force applied to the second metal object, measuring a second actual bend coordinate resulting from the force applied to the second metal object and the actual springback of the second metal object; calculating a second bend correction factor based on the predetermined bend coordinate and the second actual bend coordinate; reapplying force to bend the first portion of the second metal object a second time to a second revised bend coordinate based at least in part on the second calculated bend correction factor; and releasing the reapplied force from the first portion of the second metal object.