Of all the features of a drive system, the most popular by far is stop-to-diameter. A few weeks ago I wrote about stopping to length. Stopping to diameter is a bit more complicated than stopping to length. In fact, the control should be able to stop to length before attempting stop-to-diameter.
The earliest stop-to-diameter methods involved sliding a limit switch to initiate a stop that would result in stopping close to the desired diameter. The switch setting had to anticipate the amount of web that would be added in stopping the line at diameter.
Several parameters are required to calculate the diameter at which to stop to finish the roll at the desired diameter. These are:
- actual measured diameter
- line speed
- deceleration rate
- S Ramp rounding time
- web thickness or caliper
The actual measured diameter and web caliper are new parameters required for stop-to-diameter, but not needed for stop-to-length. The actual measured diameter is already part of the drive system as it is required for controlling tension and inertia compensation for the winding rolls. The caliper may be entered or actually calculated from measurements of length wound for a certain change in diameter.
Your drive supplier can perform the required calculations to stop to diameter. These calculations are based on the cross-sectional area of a cylinder is equal to the length wound during stopping times the web caliper.