Need a signal to start a motor on a specific position of another rotating rod by another motor once machine is started not everytime of that postion of the roating rod.

Rod is spining by a simple AC motor from turning ON the machine to turning OFF of the machine.

So we want to syncronize other motor with that rod position once this motor is turned ON too.

Any idea and suggustion please. Thank you

 

It is not really clear what you are trying to achieve, but similar events are typically done with an encoder control motor.
More info needed.!

 

Is this a new machine, or an existing machine that has been repaired but not correctly, or maybe a modified machine, changed to increase capacity or power?? These are fairly important questions.
If there are two rods, like some sort of mixer arrangement, and they must rotate at exactly the same speed, positioned so that they do not contact, then I suggest a toothed belt to keep them correctly positioned.

 

Is this a new machine, or an existing machine that has been repaired but not correctly, or maybe a modified machine, changed to increase capacity or power?? These are fairly important questions.
If there are two rods, like some sort of mixer arrangement, and they must rotate at exactly the same speed, positioned so that they do not contact, then I suggest a toothed belt to keep them correctly positioned.

Actually it is a packing machine I am designing with some advanced automation. It mechanics is something like this:

One motor is to pull wrapper plastic paper/sheet and other motor is for sealing that wrapper so pulling motor needs to be syncronized with sealer motor. Both motors are geared mean slow rotating simple motors not servo. Sealer motor is rotating with a speed from start to end and there is mechanical system that changing circular motion to linear motion two move sealer in linear motion to seal wrapper.

Second motor is for pulling wrapper. It needs to be syncronized with the position/angle of the other motor, i.e., we want to start pulling motor to start when other motor position angle is 90 degree for example. so when machine starts sealer motor starts rotating continously and other pulling motor will start when other motor angle reach to 90 degree and then stop after some small time and then start again when next time angle is 90 degree.

I think we need some kind of detector to detect angle some electromechanical detector.

 

As mentioned by Max, you would require feedback from some sort of position encoder which could be either optical or hall-cell based.

 

Welcome to AAC.

The right way to do this is using a closed loop system. That is, not counting on timing or some other aspect of operation that could result in phase problems among components.

If you are designing it now, why is the motor type a constraint? There are a few options that would make “advanced automation” much simpler. For example closed loop stepper motors are very easy to use and provide certainty of positioning. Since the control electronics are on-board, all you need to do is feed them power and control signals.

While it is not a good idea to depend on timing—as mentioned above—one thing you could do is to implement a start-up sequence that did calibration. You could put limit switches on solenoids that would move them into known positions.

The calibration routine could put a limit switch into the path of an actuating tab on each shaft, and then rotate the shaft until the limit is reached. The limit switch could them be withdrawn, and the second one calibrated in the same way.

I would make the solenoid spring return so power would be required to keep the with in place. This would be a fail safe.

In any case, actually knowing the position of the motors is much better and can account for unexpected mechanical issues interfering with the expected timing.

 

OK, This is a machine that operates within typical limit switch capabilities. Interestingly I salvaged some parts off of that one, including a gearmotor with an integral brake. So just as "Y" states, you need feedback for adequate control. An adequate brake on the motor will assure a rapid stop at the required position. But with multiple stops and starts you certainly will need multiple limit switches. At that point it will make more sense to use a small PLC to provide the timed delays and the logic. And the PLC from an inexpensive supplier will cost less than those accurate stable timers. Cheap timers will result in grief shortly after the machine is put in operation. Be sure to buy a PLC that comes with free programming software, otherwise you will go broke!!

 

The right way to do this is using a closed loop system.

That was my implication in #2 , With the such as PC based Galil motion controllers, they have the ability to electronically gear one motor off another, via each of their encoders.

 

An actual servo system is far more than what it takes. Certainly the GALIL products are incredibly accurate, vastly more than is required for this application. This is not a CNC system but a package wrapping machine. A PLC from Automation Direct will cost much less than a Galil module, and program in easy to understand ladder logic.

 

An actual servo system is far more than what it takes.

So far there have been three responses supporting feedback or closed loop, to the requirements of the system outlined in Post #4.
" It needs to be syncronized with the position/angle of the other motor, "

 

Certainly it does need closed loop control, that is not the issue that I am addressing. It does not need the accuracy needed for CNC machining or even close. It does need to be repeatable but not to the 0.001 inch, or even 0.010 inch resolution. THAT is my point. Repeatable limit switches will do the job,a servo is overkill. And there are certainly closed loop systems that do not use servos. I have designed quite a few of them.
Iif an application does not require that very tight accuracy why pay for it???

 

Thank for your great technical replies. Let me read them again with more focus later and finalize some design.

 

Some types of limit switches are far more repeatable than others. For the gearmotors, the electrically released brakes allow fairly accurate stops, depending on the reduction ratio, because the greater the step-down in speed, the less effect any brake slipping during a stop . But that is quite repeatable for a given load.
Certainly an actual servo-motor would work but every servo motor needs an amplifier and controller, and that is a lot more money than a good gear-motor with a brake.
Using an inexpensive PLC will allow yo to add timers and counters to keep track of things, and the ones from Automation Direct are what I have found to be a good deal.

 

As per my post #2, deeper mechanical details would also help with the suggestions offered.

 

Just saw a post:Automation direct is offering free training for their low cost PLCs. And I am familiar enough with the packaging sort of machines to understand the accuracy requirements.