Well, according to these guys, it was Lewis Heim. Cincinnati Milling Machine, to whom he apparently sold the patents, certainly used to be one of the the big names in centerless in the mid twentieth century. Note that they have mis-spelled Cincinnati Milicron (Sic) - it should be Milacron (company was renamed around 1970).
Some of your responses thus far mention 'Cincinnati Milacron'....I live in the town that housed the grinding division of Cincinnati Milacron. Although I can't pinoint any centerless grinding info, this area seems to have been a hotbed of engineering technology with regard to grinding for the automotive industry.
Cincinatti Milacron bought 'Heald Machine Co.' (of Worcester MA) sometime before 1980 from the Heald Family.
Heald Machine Company made many (internal?) grinding machines and much of their success was tied directly to the emergence and continued growth of the American automobile industry.
Here is a short biography of the gentlemen that started 'Heald Machine' written by the university (WPI) he attended in Worcester.
Heald Machine is (was) located right across the street from 'Norton Company' (now St. Gaubain), a maunfacturer of grinding wheels, many of which undoubtably ended up in Heald Machines.
A company that I know less about that may have implications was 'Warner Swasey'. Warner Swasey was located in the north end of Worcester and was also in the machine tool industry with some sort of grinding interest (crankshafts??). Warner Swasey may have been orphaned back and forth between Norton and Heald, and I have heard it jokingly said that Warner Swasey was in business mainly to create a market for Nortons grinding wheels (Warner Swasey may have been by the late 70s owned by Norton Company). Warner Swasey was located about 1/2 mile from both Heald and Nortons.
Here is a link to the 'Worcester Historical Society'. They may be of help researching the inventor of the centerless grinding machine.
