The profile cut into the outer ring of a straightening roll is called the straightening roll groove. Its purpose is to accommodate and guide the product to be straightened.
Angular grooves of 90°, 100° or 110° are normal for round, solid material. They are particularly advantageous for straightening ranges, i.e. wire of different diameters.
Profiled, soft or tubular material, on the other hand, is straightened in grooves which are adapted to the material to be straightened to produce a non-slip fit. Smooth, unprofiled rolls are used to flatten strip material.
See Also
Adapted from “"We do it straight" — Wire Straightening”, p. 173 (ISBN 3-00-005897-4).