I am having trouble figuring out what tension I have at the finish of my wind. I have a starting rewind tension of 80 N and my taper tension set is 35%. I had the idea that then we should end with a final tension of .35 X 80 N = 28 N, but is not that way, we have a final tension of 53 N. How can I figure it out?
Join the club. The concept and execution of winding taper should have long ago been buried. It was designed as a convenience for the lazy electrical engineer; not for any of the customers (operator or wound roll). With ubiquitous availability of PLC’s and computers, there is no reason to continue this taper nonsense. However, for those of you with old machines and lazy electrical engineers, let me offer a brief discussion of how to figure out finishing tension. From this you will see clearly why taper does not serve the customers (operator or wound roll) nearly as well as the straightforward four-point method that defines starting and ending tensions directly. This discussion is needed because these lazy electrical engineers at the winder machine builders not only gave you taper (gain) because it was easy for them, they also offered no instruction, no calibration, and no insight and what to do to maintain or use the taper controls.
On most machines, the percent taper is the amount the tension is reduced at the maximum diameter roll diameter of the machine. So, you need to know the wound roll size you are currently making and the capacity of the machine. So, let us assume 0.4m and 0.5 meters respectively. Then the tension would taper 0.35 x 80 = 28. However, you are winding only (for this example) a 0.4m roll and the tension tapers across the entire diameter range so for your roll that would be (0.4/0.5) x 28 or tapering down 22. This is subtracted from the original 80N for a final tension at the end of the roll of 80-22 = 58. Or, it is possible that the calculation for taper started at a zero diameter instead of core diameter. Why did you measure 53 N on the load cell? Simple, something is not in calibration. See rant above.