Metal strip handling apparatus and method

In the operation of a continuous strip handling apparatus in which there are uncoiling means for withdrawing strip from a coil of the strip at desired strip speeds, coiling meand for coiling the strip, strip treating means having an entry end and an exit end between the uncoiling means and the coiling means for carrying out a treatment of the strip which requires tension on the strip controlled independently of the tension on the strip in the remainder of the strip handling apparatus, loop forming means for forming a free hanging loop in the strip of varying length of strip on the uncoiling means side of the strip treating means, the loop forming means comprising drag strip tensioning roll means on the strip exit side of the free hanging loop for withdrawing strip from the free hanging loop, drag generator control means for placing controlled back tension on the strip being withdrawn from the loop as the strip moves toward the entry end of the strip treatment means, and in which there are second loop forming means for forming a second free hanging loop in the strip of varying length on the coiling side of the strip treating means, the second loop-forming means comprising drive strip tensioning roll means on the strip entry side of the free-hanging loop for pulling strip through the strip treating means and feeding strip into the free-hanging loop while controlling the speed at which the strip is pulled through the strip treating means, the method comprising

• a. providing a first auxiliary roll means interposed between the free-hanging loop and the drag strip tensioning roll means,
• b. cause the strip to make continuous surface contact with an appreciable circumferential surface area of the first auxiliary roll means,
• c. exerting a drag force on the first auxiliary roll means for placing back tension on the strip entering the drag strip tensioning roll means,
• d. independently controlling the drag force on the first auxiliary roll means to maintain by means of the first auxiliary roll means a desired, constant back tension on the strip entering the drag strip tensioning roll means, which back tension is independent of the weight of the strip in the loop,
• e. providing a second auxiliary roll means interposed between the second free-hanging loop and the drive strip tensioning roll means,
• f. causing the strip to make continuous surface contact with an appreciable circumferential surface area of the second auxiliary roll means,
• g. exerting a driving force on the second auxiliary roll means for placing pulling tension on the strip leaving the drive strip tensioning roll means, and
• h. independently controlling the driving force on the second auxiliary roll means to maintain by means of the second auxiliary roll means a desired constant pulling tension on the strip leaving the drive strip tension roll means, which pulling tension is independent of the weight of the strip in the loop.