Learning by Doing

[pstephens]

Arik and Mike,

I understand what you're saying about the decel lengths, it's just that my goal would be to relieve the operator from making an additional setup entry based on the desired part length. I would prefer he not have to worry about that.

My vision of how it would work is that a standard accel/decel profile would apply to every length entered. So, if the part was 36" long, the accel would be (say) 8", and the decel length would be 8". Same for a 72" long part. But what about a 12" long part? Can the accel and decel "ramps" intersect, such that full running speed is never reached on these shorter parts? Don't yet know enough about the programming aspect to answer this question.

Paula

 

[ArikBY]

Mike
This kind of machine MUST slow down.
With AC drive in max speed you want, you cannot stop at the right point.(That something which came from long time experience and many machines like that.even servo motor is not stopping at once.
Again it is not elevator.

 

[elevmike]

Mike
This kind of machine MUST slow down.
With AC drive in max speed you want, you cannot stop at the right point.(That something which came from long time experience and many machines like that.even servo motor is not stopping at once.
Again it is not elevator.

Well I know it's not an elevator, BUT the decell issue still remains.

Of course the machine will have to slow down before the cut. All Im saying is that how much distance depends on speed and inerita. You can either try to figure it out now, or build the machine and figure it out then.... It's not a diffucult issue to address. But the lenth of slowdown necessary is hard to determine with the info now avaliable.

 

[elevmike]

I have to go right now so I'll make this short.

It is my personal belief that the decell for all lenghts will be the same. The one decel ramp will be setup in the drive.

However if I'm wrong, then altering the decel for differnent legnth cuts will require much MORE programming, and either a stepper setup or and analog drive referance, or maybe a more siphistocated drive. So that the PLC can change the decels on demand.

As far as the operator goes, either way the operator should not have to adjust the decel for each lenght cut. You will provide an equation in the program to do that on the fly. Maybe a table or something like that.

Later..

 

[ArikBY]

I use to let the operator the option to change the slow down point with the limitaion of max and min.
In paper machine I use to let him to chenge the motor Acc and Dec too.
The slow down can help to get the best from the machine.With limitaion you cannot make any harm.
You can avoid intersect if you make your program right.Shot part cam cause problems.That the reason I use to give the operator option to speed control and slow down control with all the necessary interlocks.
If you dont want .You can pre program in a way.
Part until certain length x speed y slow down.above that different prameters.
For your first time do not make the code too complicated.

 

[pstephens]

You can avoid intersect if you make your program right.

I wasn't necessarily trying to avoid the accel and decel ramps intersecting -- I was mainly wondering if it would work that way at all. In other words, If the length desired was 12" (My customer says that's his minimum), then the motor would accelerate up to a point somewhat short of "full speed", and then immediately begin decelerating. I don't see this as a problem, if the program will work that way. For such a short part, you don't need "full speed", like you want on (say) a 60" part.

If you don't want, you can pre-program in a way.
Part until certain length x speed y slow down.above that different prameters.

That would probably work just fine.

 

[elevmike]

Again in my humble opinion....

Since this is intended to be an unattended operation, the production rate doesnt seem all that critical. Do you really care if 50 cuts take 10 mins or 1 hour??

With that in mind, life will be much simpler if you were to adjust the high speed, accel, and decel ramp for the shortest part anticipated. Then you will use the same ramps for all length cuts.

 

[elevmike]

Paula,

I'd do it myself but I'm short on time today, but call AD or check in the manuals to see if you can use counting mode 20 on X0 & X1, and add the H0-CTRIO module, and use mode 30 on that to drive a stepper. The answer may close the book on your motor drive setup.

Additonally, buy an encoder. In my opinion the encoder would be mounted on an idler shaft. You can get an hollow shaft encoer that will slide over and clam on a shoulderd shaft extension, or you can drill out a 1/2" shaft extension and slide a standard shaft encoder into it, and clamp it with a set screw. Either way you'll need an encoder to help you understand better how they work with your program. So add that to your toy box right away..

 

[pstephens]

...call AD or check in the manuals to see if you can use counting mode 20 on X0 & X1, and add the H0-CTRIO module, and use mode 30 on that to drive a stepper.

Will do. I'm going to visit my customer's plant this afternoon, so I hope to come back with a better idea of how to design this thing.

...you'll need an encoder to help you understand better how they work with your program. So add that to your toy box right away..

I agree -- another good idea

 

[Mickey]

Thought you might like these

 

[Mickey]

Or this

 

[elevmike]

Handy conversion tool

Handy unit conversion tool:

http://www.joshmadison.com/software/convert/

 

[pstephens]

Re: Handy conversion tool

Handy unit conversion tool:

Thanks Mike! That looks like a good one.

Regarding the issue of whether the DL06 could use the counter and pulse output modes simultaneously (for closed-loop cotrol of a stepper), your hunch was correct. According to "Jerry" at AD, there is insufficient memory space available to use both modes simultaneously. On the other hand, adding the HO-CTRIO module does enable closed-loop control, though it is not "internally supported". In other words, additional PLC code is required, which makes the application subject to CPU scan time. As slow as we're planning to operate this machine, however, I don't think scan time would be a big factor.

So, a stepper with an encoder is possible, only if the CTRIO module is added.

At the moment, my opinion is that the AC drive w/encoder approach sounds much more promising, and is probably simpler and cheaper to implement.

 

[elevmike]

Back to the Stepper????

Ok so from what I figure the DL06 can handle up to 5 axis control...

Without looking further, that would lead me to presume that you can run mode 20 on one module and mode 30 on another?? However you will require the addition of the H0-CTRIO counter module for the stepper drive.

Now back to the Stepper Motor:

Somewhere Paula, you stated the the required traction drive output is 12" lbs @ 12" per second. So doing a little math (shown below) I think that the AD NEMA 34 stepper might do the trick.

 

[elevmike]

So lets look at the cost of the AD stepping system:

Power supply STP-PWR-3204 $99.00
Stepper Motor STP-MTR-23079 $39.00
Stepper Drive STP-DRV-4035 $149.00
Counter Mod H0-CTRIO.......$189.00

Total = $476.00..

Disclamer: This is not a reccomendation, just a suggestion to look at.

Mike.