Vector VFD => motor => clutch => gearbox => encoder??
Vector VFD => motor => clutch => gearbox => encoder??
(OP)
We have a large planing mill which is in need of some upgrades. It originally had a DC motor driving a multi-speed gearbox. Overall gearbox transfer ratio is selected by a series of multiple-plate clutches built into the gearbox.
Originally I was hoping to eliminate the gearbox entirely, but duplicating its max torque AND speed range is really tough :( The gear ratios vary from 9:1 to 360:1!
Instead, I am now thinking about using a vector-grade motor with vector VFD to drive the gearbox, and keeping the gearbox (with new shift actuators).
The catch is, we'd like to have simple positioning ability (really just a programmable stop/reverse point). Because of the clutches in the gearbox and the possibility of them slipping a bit, it would seem desirable to have a feedback encoder on the OUTPUT of the gearbox. But that means the motor's feedback device is going to turn anywhere from 1/9 to 1/360th the motor rpm! Worse yet, that ratio will vary when you change gears.
Anyway know of a vector VFD that will cope with this situation? I have not used vector mode much, and never with encoder feedback.
Or do I just put a PLC reading the gearbox output encoder, and delivering commands to the drive?
Useful suggestions appreciated.
Originally I was hoping to eliminate the gearbox entirely, but duplicating its max torque AND speed range is really tough :( The gear ratios vary from 9:1 to 360:1!
Instead, I am now thinking about using a vector-grade motor with vector VFD to drive the gearbox, and keeping the gearbox (with new shift actuators).
The catch is, we'd like to have simple positioning ability (really just a programmable stop/reverse point). Because of the clutches in the gearbox and the possibility of them slipping a bit, it would seem desirable to have a feedback encoder on the OUTPUT of the gearbox. But that means the motor's feedback device is going to turn anywhere from 1/9 to 1/360th the motor rpm! Worse yet, that ratio will vary when you change gears.
Anyway know of a vector VFD that will cope with this situation? I have not used vector mode much, and never with encoder feedback.
Or do I just put a PLC reading the gearbox output encoder, and delivering commands to the drive?
Useful suggestions appreciated.





RE: Vector VFD => motor => clutch => gearbox => encoder??
RE: Vector VFD => motor => clutch => gearbox => encoder??
Have look at the ABB ASC800. ABB does a version of this drive that does positioning via encoder feedback, and with the adaptive programming feature could control the clutch selection. However, if all you want is reverse /stop a simple limit switch will do that for you.
RE: Vector VFD => motor => clutch => gearbox => encoder??
What I envision is a _programmable_ reverse/stop point. The operator could put the machine in lowest speed, manually control it to the desired point, press a button to set the reverse/stop point, then switch to a higher speed range to work and have the machine stop close (not necessarily within thousandths) of the original point.
Regards!
RE: Vector VFD => motor => clutch => gearbox => encoder??
RE: Vector VFD => motor => clutch => gearbox => encoder??
Anybody needs keyways cut in 30 foot long shafts, give us a yell ;)
Thanks!
RE: Vector VFD => motor => clutch => gearbox => encoder??
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include mini PLC functions including a second encoder input.