The Rangers transferred Corniell (elbow) from the 15-day injured list to the 60-day IL on Wednesday.
A right flexor strain sent Corniell to the IL on July 21, and he'll now be ineligible to pitch until Sept. 19 after moving to the 60-day IL. The move will free up a spot on the 40-man roster for right-hander Chase Silseth, whom the Rangers acquired in a trade with the Angels on Wednesday.