Sensor suggestion

We have an issue where we cut copper tubing which is pulled off of a free floating decoiler that hold the coil of copper. t has a hyand brake to keep resistance on the roll so it doesnt bind up. The issue is 80% of our scrap is related to this machine and 50% of that is related to this coiler brake adjustment.

What happens is as the copper roll gets lower the roll tightens on its self and the brake must be re adjusted as this happens.Other wise the copper either pulls against itself, the coiler's hub, or it drags across the hub flattening the copper.

I want to put an air brake on it instead with some kind of way to adjust the air break pressure when it gets low.

I havent looked into a analog type air regulator valve but I imagine one is out there.

What Im having issueswith and need advice on is what type of analog sensor to implement to run to the PLC inorder to adjust the air break pressure. What would be the best approach here?

By the way the machine feeds the copper in by clamping it and pulling it in Pneumatically so there is not data there to tap into.

Skiroy said:

We have an issue where we cut copper tubing which is pulled off of a free floating decoiler that hold the coil of copper. t has a hyand brake to keep resistance on the roll so it doesnt bind up. The issue is 80% of our scrap is related to this machine and 50% of that is related to this coiler brake adjustment.

What happens is as the copper roll gets lower the roll tightens on its self and the brake must be re adjusted as this happens.Other wise the copper either pulls against itself, the coiler's hub, or it drags across the hub flattening the copper.

I want to put an air brake on it instead with some kind of way to adjust the air break pressure when it gets low.

I havent looked into a analog type air regulator valve but I imagine one is out there.

What Im having issueswith and need advice on is what type of analog sensor to implement to run to the PLC inorder to adjust the air break pressure. What would be the best approach here?

By the way the machine feeds the copper in by clamping it and pulling it in Pneumatically so there is not data there to tap into.

Click to expand...

This is a typical "decoiler" application, and I would imagine there's a much better way than you have suggested - some of our more experienced members will be along I'm sure.

I'm certain that the pneumatic methods you are using currently can be improved upon, albeit at a cost. It's all about keeping a constant tension on the tube as it is de-coiled in the start/stop fashion you described. Anyway, it is always best to keep the largest inertial load (the drum) moving at a speed that has low acceleration, so perhaps a dancer is needed....

Over to the experts...

You could mount a weight cell on the brake measuring the brake torque and then using a pid loop to keep the torque constant. I guess it all depends on how the brake looks and how you could mount the weight cell.

Kim Andre

I've dealt with web and product unwinders and many winders, and I have three that I really liked the best for braking.

1) MagPowr magnetic particle clutches/brakes and power supplies. No wear parts, sensitive to severe impact. They can supply load cells to measure tension and all you have to do is turn a knob or send an analog tension or torque command value.

2) EDIT: Nexen air brake controller. It was a I to P controller/valve to a simple disc/caliper brake. Mechanical wear was not too bad, but the control was precise following our analog setpoint command from the PLC. We could do tapered tension, and had switch points for line stops/starts all done with one analog signal. The controller we used would probably be able to autotune to any air brake and servo valve...

With either and a PLC, you can implement automatic braking offsets to help smooth the stopping when the demand suddenly changes in either direction. As already pointed out, both of the really good solutions require loadcell feedback. Open loop brake control can be decent too, though, if the operation follows pretty repeatable patterns and you have a lot of time to tinker with it.

3) Leather strap and a weight. If you decoiler has a hub with a large outer diameter you can do surprisingly well with an adjustable weight (large nuts work nice) and a leather strap attached to the frame, but wrapped 180 degrees around a large diameter smooth round braking surface (which may already exist). Once you get enough weight to get smooth braking, replace the strap every few weeks, months, sometimes they can last years depending on duty cycle. I doubt the strap and weight/wing nut would cut it for high inertia demands but they worked great on light stuff and even the operators understood what the wing nut did...

I still think that stop/start on the drum of copper tube should be avoided if possible

daba said:

I still think that stop/start on the drum of copper tube should be avoided if possible

Click to expand...

Yes, if possible. Sometimes you have to stop a winding or unwinding operation really quickly at the worst possible inertia (full or nearly full) to prevent waste, but for normal operations a minor change to a drive accel/decel value may be the answer to a huge waste problem.

OkiePC said:

Yes, if possible. Sometimes you have to stop a winding or unwinding operation really quickly at the worst possible inertia (full or nearly full) to prevent waste, but for normal operations a minor change to a drive accel/decel value may be the answer to a huge waste problem.

Click to expand...

I didn't read it that the drum of tubing has a drive on it...

Skiroy said:

... is pulled off of a free floating decoiler that hold the coil of copper....

Click to expand...

daba said:

I didn't read it that the drum of tubing has a drive on it...

Click to expand...

Yeah, there is plenty left to the active imagination like mine.

I more pictured the copper being on a "dumb" let-off stand, but the accel and decel being controlled by the machine pulling from it.

Skiroy said:

We have an issue where we cut copper tubing which is pulled off of a free floating decoiler that hold the coil of copper. t has a hyand brake to keep resistance on the roll so it doesnt bind up. The issue is 80% of our scrap is related to this machine and 50% of that is related to this coiler brake adjustment.

What happens is as the copper roll gets lower the roll tightens on its self and the brake must be re adjusted as this happens.Other wise the copper either pulls against itself, the coiler's hub, or it drags across the hub flattening the copper.

I want to put an air brake on it instead with some kind of way to adjust the air break pressure when it gets low.

I havent looked into a analog type air regulator valve but I imagine one is out there.

What Im having issueswith and need advice on is what type of analog sensor to implement to run to the PLC inorder to adjust the air break pressure. What would be the best approach here?

By the way the machine feeds the copper in by clamping it and pulling it in Pneumatically so there is not data there to tap into.

Click to expand...

What size copper tubing and what is the velocity of the tubing as it goes to the machine? What is copper tubing roll diameter at the beginning and at the end of the roll? What does a full roll of tubing weigh??

In other words where I am going with this is what is the momentum at the beginning of the roll and near the end?

Dan Bentler

Ip

My two cents:

If you could use proportional valve from proportionair.com which is analog control 0-10V (0-100 PSI), it would be great. I have these valves very reliable installed on our robots controlling sander rpms. If you get the feedback about the coil position, you may adjust the analog voltage via PLC to this valve. It will work as a close loop control. You may have to see first which voltage window work for you to adjust brake pressure.



Yasir

http://www.proportionair.com/index....re-Control-Valves/View-all-products?TreeId=11

I have used some of these http://magpowr.maxcessintl.com/tension-control/magpowr-b-7v-b-20v-vertical-magnetic-particle-brakes in the past just like OkiePC said. We used a laserto sense the OD of the material to do a taper tension on the reel stand. It worked out great.

I used a stupid air brake on a SMC proportioning valve feed from the same style laser to do taper as well. The air brake always squealed and was just loud and annoying.

On slow application I would use a magnetic particle. On a fast application where the inertia could get up there I would use a magnet for slow speed decel and an air for rapid decel (E-STOP).

Montalvo also makes a nice unwind control like the MagPowr

I thought Montalvo was closing the doors. It has been a few years since I used them.

JeffKiper said:

I thought Montalvo was closing the doors. It has been a few years since I used them.

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Bought some things from them last year. I wouldn't know anything about their financial situation.

Their website says they are celebrating their 65 anniversary.

Rumors of their demise have been slightly exaggerated maybe?

Maybe it has been a few years since I did any web handling.