By Clarence Klassen
Turret winders should index (rotation of the turret) to a level position. How accurate should the level position be? The more accurate the positioning, the better. I will list several concerns that may call for very precise positioning of the turret. I used my drafting program to model a turret winder capable of winding rolls with a 6:1 diameter range. You will have to draft your actual turret with your roller geometry.
Layon Roller Alignment with the winding roll may be important. The layon roll nip point follows an arc or a straight line to the expected centerline of the winding roll. But a 1-degree error in the turret position will result in a 7-degree error in positioning the layon roller on the empty core. This will result in an almost 1% decrease in nip pressure. The error decreases as the roll builds.
Diameter Measurement with laser or ultrasound. The assumption is the laser is directed to the center of the core. A 1-degree error in turret positioning results in a 3.4% error in diameter measurement at the core. This error decreases as the diameter builds.
Gap Mode winding relies on accurate roll diameter information and the layon roller carriage should be directed to the center of the core. The error is the same as for the diameter error described above.
Knife and Enveloper Clearances will probably not be a problem. The incoming core will be positioned within 0.1 in. (2.5 mm).
Underwind and Overwind may result in the turret positioning being different.
Shaft Extractors and roll handling equipment may need this accuracy in positioning the turret.
The Mass of the roll may impact how accurately the turret can be spotted.
How accurate is 1 degree? Assume the turret stops using a 0.3 in. (8 mm) proximity switch and bolt head at a 40 in. (1 meter) radius from the turret center. The 1-degree error corresponds to one bolt head diameter. Hopefully, we are all achieving better than 1-degree accuracy in positioning our turrets. Stopping on a dime is probably not be good enough.