Apparatus for straightening metal by stretching

Claim 1

A drive means for an apparatus for straightening a running metal band by bending and stretching, said apparatus being of the known type that has (a) a hold-back roll assembly formed of at least one pair of rolls about which said band is trained in an Sshaped path, (b) a drawing roll assembly disposed downstream of said hold-back roll assembly and formed of at least one pair of rolls about which said band is trained in an S-shaped path, (c) a gearing for setting the degree of stretch between said roll assemblies, comprising a gearing group, one associated with each roll pair and having A. a gearing group input shaft, B. a first differential gearing having 1. a compensating gear carrier forming an input and driven by said gearing group input shaft, 2. a first output connected with a 1:1 transmission ratio with one roll of the roll pair, 3. a second output, C. a second differential gearing having 1. a first input connected with a 1:1 transmission ratio to said second output of said first differential gearing, 2. a second input formed of the compensating gear carrier of said second differential gearing, 3. an output connected with a 1:1 transmission ratio to the other roll of the roll pair and D. a regulator gearing having 1. an input connected with a 1:1 transmission ratio to said seconD output of said first differential gearing, 2. an output connected at least indirectly with said second input of said second differential gearing, said regulator gearing adapted to vary the transmission ratio between its input and its output for altering the transmission ratio between the second output of said first differential gearing and the output of said second differential gearing to change the rpm relationship between the two rolls forming a roll pair.