O/T - multiple electric machine drive?

[Bricol]

Just in-case anyone's done it, a slightly different Friday question . . .

 

I have a multi stage machine, currently 3 stages, driven by a single electric motor, the three stages linked by a gear train. Motor is around 20kW. The stages have to be in perfect time with each other to facilitate compoonent transfer at high speed from one to another.

 

Large versions of the machine simply add modules together, up to 16 stages. This of course requires more power. The simple option is a larger motor - but the thought of the extra power required being stuffed through the existing gear train is not good. Beefing the system up add unwanted costs. Plus in a jam or emergency stop/braking situation, I'm not sure whether the loads imposed would still be too high for the system.

 

So an alternative suggestion is multiple drives down the machine. But, as the load flutuates down the machine as components pass down it, what happens to the gear train? Do the torque changes lead to damaging oscillations in the backlash of the geartrain as the load is taken up, or not, by the other drives?

 

Any suggestions as to similar existing drives on machines or any other suggestions as to the behaviour of the geartrain welcomed!

 

Bri

[Colin Mill]

A friend of mine was involved in developing a printing machine that maintained the registration between the different colours electronically - each colour stage was driven by a separate motor. The registration accuracy was, I believe a fraction of a mm at a paper speed of several metres/s. He has moved on from that occupation but I'm sure can point you at some useful suppliers. If you like I can blatmail you his contact details.

 

Colin

[Richard Price]

Bri,

Electronic gearing of multiple drives is available from most inverter manufactures these days at reasonable cost (in comparison to a few years ago!).

If there a significant speed changes where the gearing need to be maintained, then servo drives would do the job, if not, then simple three phase drives with encoder feedback will certainly do the job with appropriate inverters.

We use all Rockwell Automation stuff, where the integration of servo's drives, inverters, PLC's and HMI's is all quite straight forward, and Rockwell offer system integration, or good support.

 

Edited by - Richard Price on 29 Jun 2007 09:25:04

[Bricol]

Thanks guys.

 

I'm avoiding servo drives (although I know synchronised drives are possible with them as we looked at it for a smaller machine and rejected it on cost) and sticking with conventional motors - just worried about the backlash problem as the modules will still have to be physically geared together to allow manual inching of the machine. I wasn't aware control was at a level for this not to be too much of a problem.

 

I'll talk to Rockwell.

 

Ta!

 

Bri

[Sheds Moderator]

Modern PLCs and asynchronous motors (fixed speed independent of load) are your friend here. Honeywell/other company will advise.