Web201.43c – Taper – Two Point Method
***201.43c – Taper – Two Point Method
05 Slides Duration 04.55 v 15.08.07
201.43c.01 – Title Slide
Welcome to web handling. My name is Dave Roisum. In this clip we do the reveal. The far simpler and far more intuitive way to accomplish taper. Ta Da two point method.
201.43c.02 – Programming Curves
As we explained in great detail in my winding course, the first thing the control system must do is compensate for known upsets such as changing weights and angles and geometries. This mostly applies to nip, but tension also may need treatment. Those compensations are baked into the controls and are inaide the computer cabinet and are not accessible by the operator. Of course, the service manual should describe what is being done in great detail and in particular how the service engineer or process engineer can check the calibration of the tension, nip and torque controls.
Also in the winding course we showed the three major types of curves that might run on top of the above compensations when a simple constant setting is not enough. The most common is, unfortunately as we described in the last clips, taper expressed as a percent. In this video we show an alternative that does everything that taper does, but does it much better and is much simpler, namely, the two point method. We also show how we can easily teach the operator to change settings based on which winding defects are seen and what part of the roll they are seen on.
It is very rare that a true curve or multi segment line would be needed or even helpful. Also we must consider that almost no operator or even engineer would know which rare case would benefit from this complication and how to make use of it.
201.43c.03 – The Two Point Method
The two-point method is consistent and super easy to work with. Let me illustrate by giving you a heuristic that can be taught to anyone facing winding defects. All they need to know first is where the defect is found, such as near the core or near the OD. Second is whether the defect is a tight, loose, taper or other defect.
If the defect favors the core, adjust the starting tension accordingly.
If the defect favors the outside, adjust the finish tension accordingly.
What could be simpler?
201.43c.04 – Taper Defects
Of course, the ‘other’ category of defects, which is the largest by simple count, is not sensitive at all to winder TNT settings. These defects might be caused by poor design, maintenance or operation for example.
The smallest category by far is taper related defects. This includes one or two of the types of starring. This clearly also include Type 1a and 1b telescoping where taper is the first treatment that everyone should pursue aggressively. However, even then taper is but one of a half dozen factors that can be considered as we teach in Web101. For these few defects, maximum taper is the strategy. However, now that we no longer use % taper we must accomplish it in a different way; a simple way. Merely start at maximum tightness and finish with minimum tension.
201.43c.05 – Questions?
I close with an observation that while the two-point method is somewhat new to converting, it has been the standard in the paper industry ever since the introduction of PLC and computer controls. In other words, this is not theoretical or abstract. The two-point method has been field proven over the course of a quarter century in the most demanding web industry of all.
Thank you so very much for watching this module in my plant practical video clips. If you have questions, you may want to replay this clip series. If the material still doesn’t make sense then perhaps my web or winding school might help give you the required background.