One question, were the controllers brand new replacements when you had trouble with them?

Have you thoroughly gone through them to check for wear? Are the pans balanced? that may be the broblem to begin with.

Are your feeders cable mounted with springs to absorb the feeders energy? Were the springs broken or damaged from use?

The only way I know of to measure this would be to use a light beam directed across the front of the feeder to allow it-the feeder to break the light beam to obtain the desired result of additional stroke. ■

Mike

Stroke is a function of an unbalanced moment - if you want to increase the stroke you have to increase unbalanced mass. To control it use an accelerometer in the line of action - you know the running speed and the stroke so you know the acceleration - measure continuously acceleration. There are a few guys around they can offer a relatively good, simple systems for a resonable price.

Regards

Ziggy ■

Mick

You can ring Ludowici in Brisbane they shall have a simple system available.

Ziggy ■

Mick those feeders are supposed to be as dumb as the rock they feed, are you sure you have examined all the possibilties?

How often are the operating parts cleaned/had the dust blown off of everything? you would be surprised to see how much dust and dirt will effect shaker arms on an elliptical screen-same theory in your case- any amount of dirt will throw it out if its in the wrong place or caked on from moisture.

Did anyone change the v-belts?, are the weights /eccentrics running true just as a elliptical screen would be-proper orbit-you can check this by painting dots on the rotating parts and if they are not circular in motion you have problems-How long after commisioning were the problems showing up?

Is it possible the motor shafts support bearings are bad? if they are exposed you can check this by lifting up on the pulley by hand and if there is any give at all the motor bearing is bad.

Regarding ball bearing for the control, did anyone take the old ball bearing and dump it in water to see how much displacement there was as compared to a new ball bearing?

How old are the support cables?, have they ever been changed? or did one or more break and was it or were they the only ones replaced?

Steel cables will grow or shrink in relation to temperature.

Do you have a picture of your feeders that you could e-mail me? if so send ir to lzaharis@lightlink.com

How is the upstream loading regulated if any?, If the ore is not uniform it will not work well period, also if loading is not uniform-surges in loading in any circumstance it will effect the operation of same.

Lastly you have not mentioned if the feeders in

question are angled or flat for material delivery. ■

Mick

You getting me confused - ring me on 0405 203 139

Ziggy ■

Hello MICK:

Very common industry tradenames in SAND, STONE, GRAVEL, LIMESTONE, BLAST ROCK, feeding are FMC Syntron and JEFFREY feeders. Typically engineering houses consider these 2 to be the best in the industry and considered to be equal.

1. Typically ELECTRO-magnetic or mechanical feeders.

2. Typically at 10 degree decline install angle, but sometimes 12 or 15 degrees if larger tonnages. Gravity helps with more TPH.

3. Typically always with a VARIABLE SPEED Controller device to have altimate control from ZERO tph to 100% TPH rates.

4. Can be manual Potentiometer knob controlled or a process variable speed control which can automatically increase or decrease flow by imput current variations.

5. HOPPER design is critical and can make even a nice variable speed control look like a COMPLETE USELESS device. Typically always want an "adjustable slidegate" to CONTROL material flow. Without this you have basically NO CONTROL. IE: if we were feeding MARBLES...they would run out uncontrolled and run out very fast with no SLIDEGATE up and down control.

6. WIDTH of feeder ......wider equates to more TPH

7. STROKE CHECK is easy: Mfr's will gladly supply a sticky back STROKE CHECK card which when attached to a magnetic plate and stuck on the sidewalls will indicate the LENGTH of the stroke or GAP.....and the angle of the stroke.

Here is a simple GA of an ELECTRO magnetic feeder ...

Attachments

ef_electromagnetic_feeder ga (ZIP)

■

I am fairly ignorant of the internal workings of vibratory feeders, but here are a few observations from our controlling them:

1. Vibratory feeders are inherently non-linear. Very small changes in speed can greatly affect the rate output. And yes, the input frequency of the AC motor is directly proportional to the "number of hops" regardless of stroke. Additionally, increasing the frequency will impart more energy into the conveyor and may increase the effective amplitude.

2. The nearer you operate to the resonant frequency of the feeder, the higher the effective amplitude and more unstable the control will be. Adjust the counterweights to maintain the feeder turndown within the operating frequency range specified by the manufacturer.

3. Varying the feeder tray loading, by any differences in bulk density and/or bed depth, can affect the amplitude of the feeder.

Here is my question…if your primary goal is to control the throughput, then why are you focusing on the measuring the amplitude? I assume you have a flowmeter, belt scale or other downstream weighing device to accurately measure the output of the feeder. Changing only the frequency will directly and immediately adjust the throughput.

The PowerFlex70 drive has very good resolution for the speed input, much better than the PowerFlex40. The VFD should not be a problem.

Maybe you need to instead focus on the PID tuning algorithms in your ControlLogix PLC. We are continually developing our Melfi Feed© tuning algorithms from decades of field experience. Email me and we can evaluate your application.

Regards, Delmar Schmidt

Melfi Technologies Houston

dschmidt@MelfiTechnologies.com

http://www.melfitechnologies.com ■

Easiest way to measure the stroke is by a simple sticker, posted to the side of the feeder. By looking at it while rshaking, one can see the stroke length and direction.

Automatic stroke control is undesirable, due to danger of resonance. ■

another very important point for flow rate control besides all of the mechanical adjustments.

THE design of the proper hopper opening on the top of this feeder is critical....to controlling volume .

EXAMPLE: Imagine marbles being fed....and a wide open mouth....control would be zero......

Here is a sample of a hopper design on a JEFFREY electro-magnetic feeder just for info.

Attachments

ef_hopper_design1 (ZIP)

■

try again....to attach

Attachments

ef_hopper_design1 (ZIP)

■

hello Mike: If you sent a DIGITAL pic of the feeder it would be extremely helpful speeding up replies to this particular drive method.

Feeders and feeder designs are many and the answers will be much better if we can show a pic with the question.

What is the make or manufacture of yours and what is it that you are feeding and the cubic wgt per foot of the material as these are all very critical. ■

Mick,

These machine were originally supplied in 1982.

They were designed for 1250TPH each and there was 9 units supplied along with their controllers. They were set up at between 7 and 8mm trough stroke at 1160RPM.

The machines are a tuned two mass electro mechanical machine and it looks like the original controls have been replaced with a lot of changes over the years.

We are the suppliers of this type equipment and would be pleased to talk with you to solve your problem.

Please do not hesitate to contact me.

Regards.

Kevin Bagust.

email. bagustk@syntechtron.com ■

Hi Mick

My company should be able to help with this visit http://www.reo-usa.com/ ■

A lot of people use a magnet to check stroke while vibrating screen or feeder is running.

RECOMMENDATION: I used to use a magnet with a peel off sticker on it. Take stroke, date it, comment on it and then file into your mtce book. WHY?

Next time you have a problem....you can pull out old one and figure how long the problem has been happening since the last time the machine was shown to stroke okay.

Sometimes folks, add extra weight, off-balancing machine, speed up or slow down, have material buildup or a support member breakloose and you can really track it by filing the card.

Keep stroking....... ■