Getting motion from a stepper motor?

I have been tasked with a small project for the day-job, we need a feed/rewind system for a foil printing machine.

Its a simple task - the device needs to take a start signal from the machine, accelerate a motor, run for a preset time, decelerate and stop.

Now, we can either go with a timed duration and adjustable speed or a fixed duration taken from the machine as a start & stop signal with adjustable speed.

The speed needs to be adjustable as the machine is variable speed and also the amount of foil to feed will vary depending on the job design.

So, my question is - how simple can we make this?

I would go straight for a Nema23, 4NM motor i think with a step/dir drive and simple PSU - these I have proven to be tough little cookies on my other machines.

But the control side - how would i look to achieve the speed ramping and velocity in the simplest way?

User input would just need to be a simple pot for the overall speed - this would set the amount of foil fed in the window provided by the start/stop signals.

Dave You could use something like this
http://www.ebay.co.uk/itm/Stepper-mo...-/191228844298


How about a simple timer relay for the delay bit.

A stepper with a PSU, driver and frequency generator will give you instant start at the set speed, to get ramp up and ramp down you'll need a little more complexity in your control system.
This one is crying out for a PLC, with PIC chips, Arduino etc. the world is the molusc of your choice where it comes to small control systems.
An Arduino with a few switches plus a stepper, stepper driver and PSU would give you what you need, with a little programming, you could even have a 3rd party write the software for you,
Regards,
Nick

Thanks CliveS that looks great but with the scant info listed does not look like it does acceleration. Yes a timer relay would work here.

Magicniner - thanks thats the second suggestion for the Arduino :( trouble is i have never seen one let alone programmed or used one.

Would there be any off-the-shelf products?

PLC would be my choice but going on past experience will likely blow the budget. I will pursue this option though to find out.

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Originally Posted by Davek0974

Thanks CliveS that looks great but with the scant info listed does not look like it does acceleration.

Magicniner - thanks thats the second suggestion for the Arduino :( trouble is i have never seen one let alone programmed or used one.

Would there be any off-the-shelf products?

PLC would be my choice but going on past experience will likely blow the budget. I will pursue this option though to find out.

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Dave,
An Arduino is to all intents and purposes a little PLC, it's worth a Google and have a look at what they can do and how easy the programming package is to learn, I've only dabbled to the morse code message from the on board LED stage,
Regards,
Nick

If it were my task, I would go for an arduino base solution as you could have more precise control of the variables. As I have 4 Parker Digiplan drivers (integrated power supply type) I would use one to step the motor. The question was 'How simple' though and this would be another solution http://www.ebay.co.uk/itm/Adjustable...3D191228844298

I will stick the Arduino on the list for looking at, i have been looking at those simple drivers but none have any ramp control and this will certainly need that.

Quote:

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Originally Posted by Davek0974

I will stick the Arduino on the list for looking at, i have been looking at those simple drivers but none have any ramp control and this will certainly need that.

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You might be able to use it with the speed pot connected to the arduino to ramp the speed up and down

The Arduino is well supported at www.arduino.cc There is a library of prebuilt code for stepper motor applications. If I get the time and enthusiasm I need to get down and do a stepper controller for various jobs. John S, some time ago, indicated to me the desirability of a rotary divider with programmable angles. The application in this thread is another good idea that could be programmed in a day (if I were up to speed, which I am not at the moment). I have got a raft of other projects on the list and probably not enough lifespan left to do them (based on current list !).

Cheers,

Rob

Thanks, looking now.

It seems what i want is not a stepper controller but a ramp pulse generator - the stepper controllers seem to want to run the motor themselves but i have a bigger drive to do that, this just needs to generate the step pulses in a trapezoidal ramp form.

This is a typical PLC application and is quite simple and inexpensive.

Quote:

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Originally Posted by Davek0974

I have been tasked with a small project for the day-job, we need a feed/rewind system for a foil printing machine.

Its a simple task - the device needs to take a start signal from the machine, accelerate a motor, run for a preset time, decelerate and stop.

Now, we can either go with a timed duration and adjustable speed or a fixed duration taken from the machine as a start & stop signal with adjustable speed.

The speed needs to be adjustable as the machine is variable speed and also the amount of foil to feed will vary depending on the job design.

So, my question is - how simple can we make this?

I would go straight for a Nema23, 4NM motor i think with a step/dir drive and simple PSU - these I have proven to be tough little cookies on my other machines.

But the control side - how would i look to achieve the speed ramping and velocity in the simplest way?

User input would just need to be a simple pot for the overall speed - this would set the amount of foil fed in the window provided by the start/stop signals.

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Yes but inexpensive until it comes to finding a plc capable of stepper control, although i must admit i have only used the larger more expensive units in the past - do you know of a cheaper PLC?

http://www.zappautomation.co.uk/elec...nit-23609.html
Its the last one, so once gone the price goes up.
if you want to set the speed from a 0-10V, you will need another plc, but you can set the speed in the program.
If you have not programmed plcs before you are best getting someone who has to commission the system.
I know an engineer who can do this, but he will charge you.

Also if you want to add a HMI so you can set the speed and move distance from a touch screen you can also do that with one of the HMI we sell.

Thanks Gary that looks a nice little unit but yes we will need to vary the speed somehow. The HMI is a good thought but is really not needed here, a simple pot will do the job, especially as the HMI really pushes the cost up.

Ok good luck, but if you are using a simple speed control. then you may have issues with it stalling if you set the speed too high and just enable it.
We also have a stepper driver that can run with a +/-10V or 0-10V and has limit inputs and a number of other features as well.

http://www.zappautomation.co.uk/elec...60-aa-000.html


or if you want closed loop and +/-10V like a servo.

http://www.zappautomation.co.uk/elec...or-driver.html

Quote:

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Originally Posted by Davek0974

Thanks Gary that looks a nice little unit but yes we will need to vary the speed somehow. The HMI is a good thought but is really not needed here, a simple pot will do the job, especially as the HMI really pushes the cost up.

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Thanks, i'll keep looking for the right solution. A simple speed control won't work - it needs to ramp up and down, this is the bit that makes it more complicated.

+1 for Cropwell's suggestion: An Arduino coupled with a stepper driver would walk all over this.

Yes i would agree but having seen the code, i have not got much inclination to start learning a new language now, it would need to be written and programmed for me and i feel that would push the cost up.

I can handle visual basic but it looks more like C++ or similar and makes no sense at all to me i'm afraid.

Quote:

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Originally Posted by Davek0974

Yes i would agree but having seen the code, i have not got much inclination to start learning a new language now

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The members of this forum have given you the best options and you're not happy with those options.
So pay lots more money for someone else to be bothered, it really is that simple!
Your VFD option on another forum will work great, with the required sensor and some really expensive control kit :-)

- Nick

Did i say i was not happy with the suggestions? No.

I admitted to a personal fault of not being able to start learning another programming language, i am not 19 after all and it does not get any easier. In the last few months i have started on cnc machining, 3d design, 3d CAM and a few other bits, studying a new language does not grasp my attention at all.

If that makes it sound like i am ungrateful then i apologise but we all have limitations and i have admitted this one, 10 or 20 years ago i would have jumped on it but they didn't exist then did they. Its got nothing at all to do with "being bothered" as you put it, clearly you have no limitations at all.

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Originally Posted by Davek0974

clearly you have no limitations at all.

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Not so, but I have, because I was bothered, put in the effort over the last 2 years or so to learn CAD/CAM/CNC from no level of experience at all.
Prior to that I have in my professional life learned Allen Bradley Ladder Logic in a weekend because a friend and colleague needed me to, admittedly I was already an experienced Z80 assembler programmer (All Hail Rodney Zacks!) but that had no direct bearing other than logical thinking.
Get a company in for this one, you are clearly not interested in the logical suggestions given, even though with an Arduino there is obviously something close to a solution available and having it professionally tweaked would probably cost you less than your 3 phase motor, gerabox and VFD (which would not furnish a complete solution),

- Nick

Nick your being a bit harsh here what's wrong with looking for simpler solutions, which is all daves talking about.?
Just because some half decent suggestions have been made doesn't mean there isn't better ones out there.

Dave look at Pokeys 57E. They can be run stand alone controller with it's own PLC ladder logic and have Stepper motors to match.

Looking at the process more today, I think we can simplify by orders of magnitude.

Steppers stop better than they start, especially with a load on them - I am fairly confident that we can get away with just a ramp up and run signal, no ramp down so its just ramp-up, run, stop. Don't forget - this is not CNC, an accuracy of a few mm's is fine here.

This means we can possibly look at a simple circuit based on a 555 ic with a few components to give the ramp and adjustable speed, i have seen something like that on the 'net, will try and find it again.

That, with a suitable drive and PSU will be it, nothing more needed apart from a run / stop trigger.

Hi Dave

Before I'd suggest a solution I'd question your requirements.

You say at the end of your first post:

Quote:

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Originally Posted by Davek0974

User input would just need to be a simple pot for the overall speed - this would set the amount of foil fed in the window provided by the start/stop signals.

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No it wouldn't - well not accurately anyway. Consider your mill for a moment. If you want to cut from x=0mm to x=100mm on your mill at a feed of 10mm/s you wouldn't say cut for 10s at 10mm/s. You'd say cut from x=0 to x=100 at 10. If you did the former, you'd be dissapointed. Why? Because it wouldn't actually get to x=100mm. Why? because it's not ALWAYS moving at 10mm/s because of the accel and decel ramps.

If you want to feed a specific amount of foil between the start/stop signal then that is what you should be specifying - plus of course a desired feedrate (which will be maintained during the constant speed period between the accel and decel ramps).

Dave,

It could be that a DC motor and a 555 timer circuit with a pot to set the time and a button to trigger the process would do the job. Some of the timer circuits on eBay have on board pots, so all you would need then is a trigger and a latching relay. The latch would switch the motor on and after a preset time it all drops out waiting for the next trigger.

As you say, accuracy to CNC standards is not the issue.

I use a similar circuit to hold off a pump for 7 seconds, otherwise the relay would be switching the pump on and off all the time as soon as the reservoir fluid level drops below the float switch.

Cheers,

Rob

Quote:

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Originally Posted by stirling

Hi Dave

Before I'd suggest a solution I'd question your requirements.

You say at the end of your first post:



No it wouldn't - well not accurately anyway. Consider your mill for a moment. If you want to cut from x=0mm to x=100mm on your mill at a feed of 10mm/s you wouldn't say cut for 10s at 10mm/s. You'd say cut from x=0 to x=100 at 10. If you did the former, you'd be dissapointed. Why? Because it wouldn't actually get to x=100mm. Why? because it's not ALWAYS moving at 10mm/s because of the accel and decel ramps.

If you want to feed a specific amount of foil between the start/stop signal then that is what you should be specifying - plus of course a desired feedrate (which will be maintained during the constant speed period between the accel and decel ramps).

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Yes but its not that complex - the operator set the machine up, sets the foil feed where he thinks it needs to be, runs a few sheets - not enough? just increase the speed a little, too much? then back it off when running.

Its a simple process, not CNC. :)

OK - looks like I posted at the same time as your #24 so I didn't see that accuracy was not important.

In this case I agree with Rob - a DC motor would be a better fit. A stepper is not appropriate for this. It just introduces unnecessary complexity for no gain.

Hmm, ok maybe :)

Simple pwm control would work, Will have a look at some motors, will still need a gearbox reduction though i think.

Just wrapping this up, going for a stepper motor at present cheap, cheerful and plenty powerful.

If anyone is interested in moving a stepper without a PC, take a look at the Leadshine DM805-AI drive, it has a built in oscillator and ramp controls, speed input etc, exactly what the doctor ordered, price was £106 inc Vat.