conveyor/bag stitcher problem.

BillyH · Mar 9, 2013

I have been asked to take a look at an industrial conveyor/ stitcher which has an intermitent fault. The process involves bags being loaded then, placed onto the conveyor where, they are then driven through the stitcher mech to close the bag. All is fine mostly but, on occasion, the conveyor will stop and the stitcher will carry on as usual. We have had issues with vibration on this machine previously, where a cable, connected to the drive had broken but would remain in contact with the terminal, this cable would disconnect momentarily (enough to stop the conveyor) when the stitcher was activated. The conveyor would run all day without the stitcher working but would stop occasionally when activated. There is no electrical relationship between the stitcher and the conveyor, by this i mean either can run with or without the other. Could excess vibration on a contactor/drive etc be the problem? I should add, the control panel shakes like hell when the stitcher is working
I'll try and post some pics later

stef · Mar 9, 2013

Hi Billyhas,

Check whether it is driven by an ac or dc motor, if dc then there could be a problem with brush gear. Like you said, it could be a loose connection in the control circuit, a dodgy contactor, faulty supply cable, slipping drive belt, loose pulley, anything, really. Are there any limit switches or photo switches involved? If so one may be mis-triggering.

malcoa · Mar 11, 2013

I think that the vibration is the cause as you suggest and it is exasperating a fault on the conveyor that exists and lies dormant until the vibration occurrs, possibly originally caused by vibration, copper cable (especially solid) work hardens and can crack beneath the insulation when under large amounts of vibration.
You should try to isolate the vibration in anycase, plenty of anti vibration mounts about.

plugsandsparks · Mar 11, 2013

Assuming the conveyor contactor has dropped out, i would start by tracing all cables and components in the stop cct and checking for bad connections and the like. A diagram would be helpful for you to logically go through it cable by cable and component by component.
If the contactor is still in and the conveyor has stopped have a look at the cable to the motor or the motor itself.
Also is it dropping out due to overload, or is the overload faulty.
Theres a few to keep you going