Measuring Strip Width

If the accuracy is only 0.25" and the strip is a fixed width you will not need to scan the whole width, all you would need is two short range lasers to monitor the edges, one on each side...

Then with the lasers at a fixed width you can monitor the strip width much more accurately and cheaply...

Even if the strip is different widths the lasers could be preset etc...

In fact why use lasers? with an accuracy of 0.25" all you would need is some simple opto sensing device to detect the edges?

John.

You can use 2 laser 8 one fix and one mobile) so you have a wider measuring range and a much better preciosion with lower prices.

If you need more detail you can contact me

I think also there no need al laser equipment for your .25" accurancy. just optic equipjment enough. if you really like laser measurement. I can offer you one.

Thats a prety good question, First of all what are you slitting, paper,etc....lot of variables there. You can run spring loaded paddle wheels to give you a 4 to 20ma signal for your HMI interface as well as a time reference histogram, if you go outside of your tolerances. That makes a really bad roll on the winder when you do that. So you go outside the tolerances do you have a doctor roll that will compensate for the out of tolerance strip or do you just recycle it at a cost and start over which can be quite expensive. I have worked with quite of bit of slitters and as you said you want the strip within tolenrance, but you didnt memtion if all the strips are be cutting in the slitters at the same width (we set our slitters at variouse widths) to get the most out of our rolls as per customer need.I may could help you or put you on to someone who can if there was a little more information out there. It can be done and sometimes at a cost. Q&A allways wins out though but usualy they do not want to pick up the budget to get what they want so there has to be a compromise...good luck

A lot of good feedback here, thanks all.

It is a pickle line, no slitting just edge trimming and winding. Pretty simple really. The width measurement is being performed immediately after the side trimmer as one of its purposes is to aid the operator in setting up the blade gaps. This is a 1964 GE Acid tower pickle line. Should be in a museum really. Most of the functions are manual. Setups and speeds are manual and done with field rheostats. I've been fighting like mad to get some intelligence here and have managed to get an AB DCS and a level 1 ethernet network. Our workers union has opposed the use of lasers as they fear it will harm them. We couldn't use laser pointers during seminars/presentations. This attitude is changing as we've been able to show them how modern laser distance meters etc are much more efficient with low power and therefore much safer.

This environment is very harsh so we typically avoid using mobile scanners. The drives (splines/worm gears) get damaged and cause line stops. Scanning lasers are terribly expensive so I agree with the low cost optical sensors as they are cheap and perform well within the tolerances we need.

Have you seen the Scan-A-Line product by Harris Instrument Corp? They use scanned light emitting diodes to measure width and strip position to .005 inch. There are many installed on pickle lines.