Casing Roller Operations & PDF Download
Use a casing roller when the casing is slightly collapsed. Casing rollers are light-duty tools. We recommend for you these article to read:

Tool Description 

The CASING ROLLER is specifically designed for repairing casing and differs from any other repair tool intended for this application in that it does not include any small parts to be worn, broken, or lost in the well. We shall take the BOWEN Type as an example.

The Bowen Casing Roller rolls the casing out to its original ID dimension.
https://www.drillingmanual.com/casing-roller/