Diaphragm turning chuck

automatic2-jawclamp

Another “High Pressure” challenge for Northfield. Allied Machine Company manufactures a line of spade drill inserts ranging in size from 3/8-inches to 4-inches in diameter. They asked Northfield to provide a workholding device that could accurately hold their drill inserts in position during the finish- grinding operation. Several factors made this a challenging assignment. The small drill inserts offered very little surface to clamp on, yet a very high clamping force was needed to hold them during the grinding operation. And, of course, repeatability was essential. A Z-axis clearance problem caused by the grinding wheel added another problem. And, as if that wasn’t enough, our design had to be able to function reliably in an abusive environment, filled with grinding grit. After much thought, Northfield’s engineering department came up with a solution to Allied’s “High Pressure” challenge. We supplied a special 7-inch diaphragm chuck with two jaws made of air-hardening too-steel (60-63 HrC) that delivers up to 2,500 pounds of clamping force to the drill insert. The entire operation is repeatable to within 1/10,000th of an inch. The chuck is less than 2-inches high. This low profile, combined with the extended cone- shaped jaws, solved the grinding wheel clearance problem. And finally, because it is a diaphragm chuck, it is completely sealed and has no metal-to-metal moving parts – a perfect solution for the grit-filled environment of the grinding room.