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Drake Manufacturing Services Co. LLC delivered a so-called "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. Stig Mowatt-Larssen, Drake's Director of Research and Development said, "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. 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 350mm diameter and 750mm of thread length. It is capable of producing crowns with radii from 1.9m to 999m with lead angles to 5° RH/LH.
Like all Drake machines, the Crown Grinder comes with a simple to use menu system for programming thread forms, part descriptions, as well as grind and dress process parameters. The machine is equipped with linear motors on the work and wheel axes for years of maintenance free operation and high dynamic stiffness for chatter-free finishes.
Related Glossary Terms
- computer numerical control ( CNC)
computer numerical control ( CNC)
Microprocessor-based controller dedicated to a machine tool that permits the creation or modification of parts. Programmed numerical control activates the machine’s servos and spindle drives and controls the various machining operations. See DNC, direct numerical control; NC, numerical control.
- dynamic stiffness
dynamic stiffness
Measure of a machining system’s ability to dampen vibration from a forced input. If the dynamic stiffness of a system is not sufficient to dampen vibration, chatter occurs. See static stiffness; stiffness.
- feed
feed
Rate of change of position of the tool as a whole, relative to the workpiece while cutting.
- fixture
fixture
Device, often made in-house, that holds a specific workpiece. See jig; modular fixturing.
- grinding
grinding
Machining operation in which material is removed from the workpiece by a powered abrasive wheel, stone, belt, paste, sheet, compound, slurry, etc. Takes various forms: surface grinding (creates flat and/or squared surfaces); cylindrical grinding (for external cylindrical and tapered shapes, fillets, undercuts, etc.); centerless grinding; chamfering; thread and form grinding; tool and cutter grinding; offhand grinding; lapping and polishing (grinding with extremely fine grits to create ultrasmooth surfaces); honing; and disc grinding.
- grinding wheel
grinding wheel
Wheel formed from abrasive material mixed in a suitable matrix. Takes a variety of shapes but falls into two basic categories: one that cuts on its periphery, as in reciprocating grinding, and one that cuts on its side or face, as in tool and cutter grinding.
- stiffness
stiffness
1. Ability of a material or part to resist elastic deflection. 2. The rate of stress with respect to strain; the greater the stress required to produce a given strain, the stiffer the material is said to be. See dynamic stiffness; static stiffness.
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