Choosing motor and servo drive


Thread Starter

Gabriel Preliasco

I have a flexographic machine whit 6 print stations synchronized with a line shaft, gears, gearboxes and clutchesand. I want to go
shaftless. On a shaftless press, each print station is individually controlled by servo drives, and all printing operations are
electronically synchronized by a master motion controller.
I have used the motion book of rockwell but I couldn't find a solution. The inertia of the roller is 0,03 Kg-m2 or less and the velocity is
320 rpm or less. The roller and the drum hardly touch each other so I suppose the torque is minimum.
I would like to know:
Which servo motor of Allen Bradley family is more suitable?

Davis Gentry

What is your controller? I do not know of any
Rockwell product which will give you accurate control in an application like this.

Davis Gentry
Applications Engineer
Delta Tau Data Systems

Thompson, Tommy

I have worked on several Press applications using Servo Driven flexographic tools along with Die Cutter, Glue Applicator, Perforator tools, etc..

We have used Indramat SERCOS Drives and PacSci SERCOS Drives driven from either an Indramat CLC master controller or an Automation Intelligence/Sanyo Denki SERCOS master controller. Check this Website for additional

What about the 1394 multiaxis drives? I have not used them myself, but they look pretty capable. They may be limited to four axis however.

Bill Sturm

Davis Gentry

My last direct experience with synchronized motion using Rockwell products was almost two years ago, and they seemed at that time to work best at low resolution requirements such as a loosely synchronized conveyor line or suchlike. A multistation printing application will have generally very high requirements. My latest experience was six months ago on a pick and place line - the A-B factory guys spent two months on site trying to get a fairly simple application going (12 axes, but requirements not too tight). We were brought in to replace them. But my recent experience with them is pretty scant - anyone out there have a better feeling for them?

Davis Gentry
Delta Tau Data Systems
Check out mitsubishi's Motion Controler either in the Q-series or the A1S series. They will allow you to lay out the press in a virtual machanical
system, just as it runs now. Then it will write and control the SFC code for you and allow you to inteface the machine functions in a ladder format.
This is clean and very fast.

Good luck

Trevor Ousey

I would have thought a 1394 GMC could handle the application, possibly using 'axislink' to give up to eight axis. I would also look at a ControlLogix with some MO2 motion modules going to some analogue servo drives. This could expand further to sync the Rewind and Unwind to the print station master, if your using draw control.

I would suggest talking to your Rockwell product manager.

Trevor Ousey

First you need to characterize your application performance requirements (max accel/decel/speed, max angle error allowed etc.)and load parameters. Then CONSULT with MFG's app specialists. Electronic synchronization apps can be tricky so shouldn't select components yourself with "cookbook" selection programs that don't consider app/dynamic response suitability.

Depending on your performance requirements, high accel-speed/high dynamic accuracy synchronization can be very demanding for a drive system. If all your slaves are to follow a virtual master, the closed-loop response (current/vel loop) of the drive is critical. Do you need just very tight speed ratio control or actual angular synch control i.e. pulse by pulse following?

The highest performance method I've worked with actually compares the master pulses with the slave pulses (electronic gearbox ratio optional)
pulse-by-pulse and adjusts the slave accordingly. A "feedforward" control feature helps reduce the following error by pre-matching the slave ratio.
Any speed ratio method alone can't guarantee high dynamic angle following.

Tom Gianni