Originally Posted by mohandes

Dears,

I have tested a vibrating screen last week and had abnormal vibration which I can not explain how happened.

So I would like to explain you what I have seen and I would be pleased if inform me about your idea or experience for similar cases:

1- the vibrating screen designed to work with linear force excitation from two vibrating motors which you can see in attached file motor installation on screen. Stroke angle is 45 degree and screen inclination about 10 degree.

But:

when we turn on motors:

vibration angle on side walls about 90 degree, approximately we didn't have any longitudinal vibration, why?! I don't know

high lateral vibration

as you can find in photo, motors has not synchronzed, why?! I don't know

2- I thought that the lateral vibration happened because of motors arrangement. so I tested it with other motors arrangement with circular excitation according to attached picture.

motors are not synchronized, why?! I don't know

lateral vibration exist but more lower than previous case

no material movement

thanks in advance for your guidance

Mohandes

You can get this problem if your mechanisms rotate in the same direction - they should be running in opposite directions.

Regards

Ziggy Gregory

www.vibfem.com.au ■

Namaskar,

Greetings and salutations Mohandes,

Seeing the excellent photos you provided Mohandes

I think all your problem is the position of the weights

as they are not positioned correctly and identically.

If your weights are not positioned identically you will

have one motor and its wieght opposing the other motor

and wieght while working and essentially stalling the

screens ability to screen aggregate.

If either of the wieghts is advanced past the locked position

of the other wieght this motor and wieght will always advance

the throw of the screen on this side farther countering and

canceling the the other motor and wieght.

When you turned the motors you effectively eliminated

any screening ability as the frame could not move. ■

Originally Posted by ziggy

Mohandes

You can get this problem if your mechanisms rotate in the same direction - they should be running in opposite directions.

Regards

Ziggy Gregory

www.vibfem.com.au

Mohandes

I have noticed that you have two different positions for the mechanisms - you can't change the position as you want, the postion and rotation of the mechanisms then is dependend on the screen design and location of your mechanisms versus the centre of gravity.

Regards

Ziggy Gregory ■

Mohandes

If you have the case of natural frequency you have following options:

- Impact test done to determine the natural frequencies and then stiffeners on the screen added/removed/changed

- install a frequency controller and find the correct operating frequency

- have FEA done to determine natural frequencies and feasible modifications to the screen - that should be actually done before screen design and that would most likely save you the trouble and cost now.

Regards

Ziggy Gregory ■

CHECK OUT THIS LINK for helpful info:

http://www.jvivibratoryequipment.com...flowchart.html

Basically: Linear motion vibrators mean linear motion.....stroking plus minus 45 degree angle in a straight line stroke...to actually move the material up into the air and advance it down the screen from feed end to discharge end.

If too steep of angle, only defined in actual fact by a STROKE CHECK while running....material will NOT ADVANCE but, basically go up and down at say 90 degrees or even 60 degrees off ZERO degrees flat or horizontal plane and the material GOES NO WHERE...just humps up and down.

..................

LINEAR MOTION: weight setup as shown in pics......all weights on all rotating weighted wheels MUST MUST be exactly the same position or all heck will break loose. All we are in fact doing with those weights are loading up a STRONGER lift or eccentric STROKE or if subtracting the weight offsets, a lighter less agressive linear stroke and that is all.

.................

There are NO plug type weights that are pulled out of or added into that weigted wheel setup....hence no circular or elliptical stroke pattern could or would be added to the setup.

hoping that helps.

George Baker MODERATOR ■

I have read your reports on forum.

It looks like you are a OEM for vibrating equipment or you use vibrating equipment for your works.

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Our company is a Italian company having 40 years of experience in manufacturing and supplying vibrating motors for vibrating equipment worldwide for various applications.

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We are already supplying to some major OEM's for Mining equipments, Rice Milling, Foundry Equipments, Construction Equipments etc.

We are presently having foot mounted electric vibrating motos, ATEX compliant Foot mounted Vibrating Motors, Single phase 3000 rpm vibrating motors, Flange motors, Pneumatic Ball type Vibrator Motors, Intermittent duty vibrator motors and High frequency vibrator motors ( 3000, 6000,9000 rpm).

I request you to please send us your requirements of vibrating motors enabling us to send you our best prices along with any help required from us.

Kind Regards

Amit Jain

Indian Sales Manager

O.M.B. Srl

Email: amit.jain@ombvibrators.com

Ph: +91-9999676665. ■