cut to length application

[david90]

Not much for diagrams....

You need to have a signal on the blade that its in the top position then you will enable the operator to jog and have a manual switch, then you can have that sub-routine run when in manual also have an auto position and run the auto sub when true

The best way I have found to write this type of program is to talk it out.... and make every 'state'ment one paragraph then you can move the paragraphs where needed

You know that in your first cycle the machine needs to be in home position, so the first would be check to see that all safeties are in place and the blade is in the upper pos

Next feed the material... {insert code} .... Stop feed

Cycle blade ( more code} .... verify blade

Rev material {more code}....

Cycle blade ( more code} .... verify blade is up


This is something like I would start with, that said Peter is the pro so anything he says read it...

Do you have some sample plc code of the structure you mentioned above? It doesn't have to be for cut to length.

 

[geniusintraining]

What brand of PLC are you going to use or are using?

I should have both... what not to do and what I think are good

 

[david90]

What brand of PLC are you going to use or are using?

I should have both... what not to do and what I think are good

I'm using an eaton/durant FUSION controller. Look at my first post to see a pic of it. It has limited ladder logic capability but for my application I think it's good enough.

I'm having a problem reversing the motor with this controller. The controller analog output is from 0-10V but the DC drive needs a -10V to reverse the motor. What can I do about this problem? Is there a module that I can buy to translate 0-10V to -10V - 10V ? For example, 0V input would output -10V, 5V input would output a 0V and 10V input would output 10V. I don't care about the lost of resolution.

Thanks for your help

 

[david90]

bump for help

 

[geniusintraining]

bump for help

I am not going to be much with them... I have just about every PLC program, but not Eaton

If I were you I would think about switching to to a brand where I could get more support or check with them and see what kind of local support they have to offer

Its an easy enough program but you need to get the basics then I am sure you can fill in the blanks

 

[david90]

Do you know of any device that could translate 0 - 10V to -10V to 10V?

 

[Peter Nachtwey]

My Cut to Length Program

I didn't bother with the 1 second delay. I would not waste the time and using the in position bit on the motion controller. I would also have inputs that tell me when the shear is up and down instead of using delays. This way the machine can go as fast as possible.

http://www.deltamotion.com/peter/RMC/Cut2Length.zip
I spent about 1 hour on this. I figured what the heck I didn't have a demo so now I will.

I am assuming that all the user programs will run on the same task so there is no chance of activating a jog while in run mode. Now that I think about it I should have a better check before going into run mode. I should have IxRun and not ( IxJogFwd or IxJogRev ). I will update that tomorrow.
The program is really pretty simple otherwise.

If anyone is interested I can get the simulator working tomorrow.

 

[geniusintraining]

... that said Peter is the pro so anything he says read it...

Thats what I was talking about... very cool Peter

One thing... I have always seen a cam switch on the knife/assy. cycle that was the signal to the cutter for the stop and then another that it was in top dead center and did not see this on yours, with yours is it just one cycle and always stops at top? then just a switch to verify? all the cutters I have made/worked on have been older technology so just wondering how you are doing/recommending them

 

[Peter Nachtwey]

One thing... I have always seen a cam switch on the knife/assy. cycle that was the signal to the cutter for the stop and then another that it was in top dead center and did not see this on yours, with yours is it just one cycle and always stops at top? then just a switch to verify?

I am assuming the knife simply goes down and then back up and there is an input that indicates the knife is down and another input that indicates the knife is up. This is a very simple cut to length system. We haven't been told otherwise.

all the cutters I have made/worked on have been older technology so just wondering how you are doing/recommending them

It depends on the need. I have customers that cut steel from big rolls into sheets for making dish washers, dryers, washing machines, refrigerators and cars. The big rolls of steel weigh far too much to start and stop for each cut like in david90's project. In this case one must cut on-the-fly. When cutting on-the-fly the shear may move back and forth like a flying shear or the shear may be rotary. Rotary shears are the trickiest as the math is complex because there isn't any linear motion or even a time where the gear ratio is one to one for more than an instant while making the cut. Here is an example of a flying shear
http://www.deltamotion.com/peter/Videos/FlyingShear/FlyingShear.mp4
You can see a flying shear requires a few calculations that david90's simple cut to length doesn't. Normally on a flying shear we control the shear too so we can move it down, wait for the shear to go past a position where we know the shear has cut the material and then immediately back the shear up. Since we know the position of the shear we know when the shear is just clear of the material so the move back to the beginning of the cycle.

The rotary shear is complex because as the shear gets within 30 degrees of the bottom the shear must match the horizontal speed of the material so the material is not disturbed when the cut is made. When the shear is 30 degrees past the bottom it must rotate so that it gets to the point 30 degrees before the cut at the right position relative to the material being cut so the next cut is the proper length. I believe I have a video for that too but I must not have reposted that one.

 

[david90]

I am assuming the knife simply goes down and then back up and there is an input that indicates the knife is down and another input that indicates the knife is up. This is a very simple cut to length system. We haven't been told otherwise.


It depends on the need. I have customers that cut steel from big rolls into sheets for making dish washers, dryers, washing machines, refrigerators and cars. The big rolls of steel weigh far too much to start and stop for each cut like in david90's project. In this case one must cut on-the-fly. When cutting on-the-fly the shear may move back and forth like a flying shear or the shear may be rotary. Rotary shears are the trickiest as the math is complex because there isn't any linear motion or even a time where the gear ratio is one to one for more than an instant while making the cut. Here is an example of a flying shear
http://www.deltamotion.com/peter/Videos/FlyingShear/FlyingShear.mp4
You can see a flying shear requires a few calculations that david90's simple cut to length doesn't. Normally on a flying shear we control the shear too so we can move it down, wait for the shear to go past a position where we know the shear has cut the material and then immediately back the shear up. Since we know the position of the shear we know when the shear is just clear of the material so the move back to the beginning of the cycle.

The rotary shear is complex because as the shear gets within 30 degrees of the bottom the shear must match the horizontal speed of the material so the material is not disturbed when the cut is made. When the shear is 30 degrees past the bottom it must rotate so that it gets to the point 30 degrees before the cut at the right position relative to the material being cut so the next cut is the proper length. I believe I have a video for that too but I must not have reposted that one.

My application is cutting a roll of steel of into small pieces too. The shear does not go back and forward like your customer's shear. It just goes up and down. Because of this, cutting on the fly will cause the steel to catch on to the shear upon retraction.

 

[Peter Nachtwey]

My application is cutting a roll of steel of into small pieces too. The shear does not go back and forward like your customer's shear. It just goes up and down. Because of this, cutting on the fly will cause the steel to catch on to the shear upon retraction.

The Cut2Length program would work then. If you look at my program it backs up using the RevDist and waiting for the move to complete before raising the shear. Then makes a relative move forward the CutLength+RevDist in on move. Notice that I removed the 1 second delay since that wastes time and doesn't guarantee anything except one second has past. I think it is better to actually check events using feedback devices or inputs rather than timers. The cost of the extra inputs will pay for themselves in increased production.

Now that I think about it there needs to be another improvement in my program.
I think I can simplify things and remove at step or two.

 

[geniusintraining]

I reverse the motor prior to retracting the shear to prevent the shear from catching on to the material on its way up.

Have you made the machine yet? everyone that I have made (not a lot but a few) have two blades.... one stationary on the bottom and the top goes up and down, both have to have a 'relief' and this is what makes the material not catch, this would simplify your program


Peter, I forgot about my paper days... I did work on fly cutters in the printing industry, I worked for IP for about 7 years in the printing division before they sold it, they are very fast in comparison to the guillotine style, we called them 'rotary cutters'