J
Hi all,
I have a problem here that I could use a little help with.... I have a overhead monorail chain conveyor project that I am working on. I am attempting to retrofit the 3 HP eddy current drives on this conveyor with 3 phase motors and AB 1305 VFDs. I just got done re-installing the eddy current drives after a failed attempt to make the motor/VFD combination work. The conveyor has two identical cat drive units, with appproximately 600/1 reduction from the motor to the output shaft of the drive.
The trouble that I am having is I can't seem to balance the two drives out. One gets ahead of the other and I end up with too much tension on one side of the chain loop or the other. There is a chain take up on one side of the loop which provides a little forgiveness, but the other side of the loop is a direct chain connection between the two drives. I have tried a number of different configurations in the VFDs, but after the conveyor runs for a while it gets out of whack and needs human intervention to get balanced out again. The conveyor layout is relatively flat, so the parts won't present a large load.
I am thinking about finding some kind of a load cell to allow me to monitor the tension on the side of the loop without the take up and vary the speed of one drive based on the chain tension. That way I can balance the chain tension evenly between the two drives. I was hoping to be able to simulate this by monitoring the drive current and varying the speed of the drive to keep the tension constant, but the gear reduction is so high that the motor doesn't even seem to notice that a conveyor is connected to it! I did go a little wild on the motor size, 5 HP that we had on the shelf from a scrapped machine, but I essentially derated them to about 2-3 HP by limiting the current with the VFDs.
If anyone out there has experience with a problem like this I would sure appreciate your comments. At the start of this project this didn't look like it was going to be a big deal, but I spent all July 4th weekend fighting with it and I couldn't figure out a way to make it work.
Thanks in advance for the help.... I'm not an engineer so go easy on me with the PID loops and all that stuff... If anyone knows of a device that will measure the tension on the chain and get me 4-20 ma back to the PLC I would appreciate that also!
Jeff
I have a problem here that I could use a little help with.... I have a overhead monorail chain conveyor project that I am working on. I am attempting to retrofit the 3 HP eddy current drives on this conveyor with 3 phase motors and AB 1305 VFDs. I just got done re-installing the eddy current drives after a failed attempt to make the motor/VFD combination work. The conveyor has two identical cat drive units, with appproximately 600/1 reduction from the motor to the output shaft of the drive.
The trouble that I am having is I can't seem to balance the two drives out. One gets ahead of the other and I end up with too much tension on one side of the chain loop or the other. There is a chain take up on one side of the loop which provides a little forgiveness, but the other side of the loop is a direct chain connection between the two drives. I have tried a number of different configurations in the VFDs, but after the conveyor runs for a while it gets out of whack and needs human intervention to get balanced out again. The conveyor layout is relatively flat, so the parts won't present a large load.
I am thinking about finding some kind of a load cell to allow me to monitor the tension on the side of the loop without the take up and vary the speed of one drive based on the chain tension. That way I can balance the chain tension evenly between the two drives. I was hoping to be able to simulate this by monitoring the drive current and varying the speed of the drive to keep the tension constant, but the gear reduction is so high that the motor doesn't even seem to notice that a conveyor is connected to it! I did go a little wild on the motor size, 5 HP that we had on the shelf from a scrapped machine, but I essentially derated them to about 2-3 HP by limiting the current with the VFDs.
If anyone out there has experience with a problem like this I would sure appreciate your comments. At the start of this project this didn't look like it was going to be a big deal, but I spent all July 4th weekend fighting with it and I couldn't figure out a way to make it work.
Thanks in advance for the help.... I'm not an engineer so go easy on me with the PID loops and all that stuff... If anyone knows of a device that will measure the tension on the chain and get me 4-20 ma back to the PLC I would appreciate that also!
Jeff