Machine vision in Double Vision coil winders from Engineering by Design, San Jose, www.ebdesign.com detects wind angles, without physical contact, to 0.02°. Previous measurement techniques used a mechanical arm fitted with an angle sensor. But as wires get smaller, contact with the mechanical sensor arm changes the wind angle and introduces errors up to 2°.
"Machine vision eliminates the error and boosts control accuracy by a factor of 100, which equates to more consistent product and less waste," says EBD President, Dale Henson. "Maintaining a steady tension of 0.2 gm and a wind angle of 0.1° makes it possible to produce coils from 0.0004-in.-diameter platinum wire."
Automatic mandrel and filament tensioning and variablepitch control let the machine wind coils with multiple and repeating combinations of pitch, direction, and length. Closed-loopfilament tension and slack control maintain programmed tension at speeds to 6,000-mandrel rpm and faster. Brushless servomotors drive the traverse mechanism and both mandrel ends, eliminating a back shaft. The control system records statistical data for each wind including the mean and standard deviation of all measured variables to verify product quality and refine the process.