Drake Manufacturing Services Co., LLC recently delivered a “drum” or “crown” grinder to an Asian manufacturer of tapered roller bearings. The drum is a threaded steel drive roll used in a centerless grinder to move the tapered rollers across the face of the grinding wheel. The rollers start on one end as rough blanks and emerge on the other as round rollers. The drums wear over time so the Drake grinder not only grinds threads on new drive rolls, but also re-grinds the threads after they are worn.

This 8-axis precision CNC drum/roll grinder is also called a crown grinder because the outside diameter of the drive roll is actually shaped like a barrel. The B-axis of the Drake machine pivots during the grind to keep the grinding wheel tangent to the radius surface of the roll. 

“It was rewarding to see another customer’s eyes light up when cycle times on four different drums ground during runoff at Drake were reduced from 4 hours to just 30 minutes,” said Stig Mowatt-Larssen, Drake’s director of research and development. “Our machine design and hydrostatic spindle combination make aggressive grinding possible — even of hardened D2.”

The Drake GS:CG, Grinding System:Crown Grinder, is used by tapered roller bearing manufacturers in the USA and Asia to regrind drums/rolls used in their manufacturing process. The part holding fixture will accommodate most drive, feed, support and back-up rolls used in tapered roller bearing manufacturing including Cincinnati #2 and #3, Koyo, Nissin, Seibu, and others up to 350 mm diameter and 750 mm of thread length. It is capable of producing crowns with radii from 1.9 m to 999 m with lead angles to 5° RH/LH.