Check out US patent #6901782, "Method and Apparatus for Forming a Modified Cross-Section Wire Material". I'd also go back to any patents referenced as prior art. That should get you started. I used "wire cross-section roll" (without quotation marks) in Google; you may want to look at some of the other 828,000 items it found [this was the very first].
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" Ignorance and arrogance have more in common than their last four letters. "