Screen Lateral Vibration
Dear Sandeep
It is very interesting that I have the same problem as yours right now.
would you please inform if you have solve it and how.
I have changed vibratory motors but it doesn't have any effect. ■
Re: Screen Vibrating All Directions
Having General assembly drawing or photos may be more helpful.
Requesting feedbacks if the problems are solved. This would be more beneficial to all.
Thanks & regards, ■
Some Suggestions From Afar......
1. is there more then one vibrating screen on the structure?
2. do a REED METER check on the structure for errant vibrations
3. you must have 200 percent safety factor built into the structure to handle the G's of the screen, if not enough structure....you will get fluctuating actions back into the screen box
4. proper sized coil springs on the screen box?
5. TRY slowing down or speeding up the RPM by say 50 RPM and see what happens.
GEORGE BAKER, MODERATOR ■
Screen Vibrating In All Directions
The most likely problem is the structure is resonating as its natural frequency is matched by screen vibrations.
This type of problem occures when screens are mounted on steel structures at considerable heights.
You can get the vibration analysis done. The person doing this analysis will suggest modifications / alterations tostructure to eleminate this wayward resonant vibrations.
Vinayak Sathe +91 832 2538294 vinayak.sathe@gmail.com ■
Re: Screen Vibrating All Directions
Vinayak,
Will adding additional mass to the screen solve the problem. ■
Re: Screen Vibrating All Directions
Resonance occurs when the driving frequency (usually 60 Hz) is equal to the natural frequency of the screen. By adding mass you will be changing the frequency of your machine. To solve the resonance problem you must stiffen the machine to lower its natural frequency.
Other possibilites of your problem:
1. Motors are not synchronized. You can confirm this by removing the covers and applying a strobe light when the motors are running. If this is a problem your mounting surface/structure is weak or you have a bad motor.
2. The support structure is flexing or has resonance reaction. Reinforce the support stand.
Hope this helps.
Danny Guerra,
Project Engineer
JVI Vibratory Equipment Inc.
Houston TX ■
Screen Vibrating In All Directions
The solution may be stiffening stucture to change its natural frequency.
If the screen ismounted on RCC or masonary, such problemis not encountered.
The person carrying out vibration analysis will recommend solution. ■
Re: Screen Vibrating All Directions
Please refer to the problems i was facing with the trials of one of our 2 x 4 m screen.
Today i added additional stiffening angles along the line of action of the vibrator and the result is that the screen works absuluely fine for the first 1 min and then start fluttering.
Istill have space for more stiffeners but im afraid i'll be very soon left with no space on the side walls to put stiffeners.
Is this the correct method to correct such a problem. Am i heading towards a solution for the problem or am i landing into more problems.
Regards
Sandeep ■
Re: Screen Vibrating All Directions
Shoot me if you wish, but it sounds like you have your motors running in the same direction. ■
Re: Screen Vibrating All Directions
hii dave.... you are shot.
hehehe ........ the motors are proper. We had 7 screens designed on the same line. 2 of them are giving me trouble. rest run like mercedes benz.
I have tried everything possible i could.......... added stiffeners, did a bracing of the support structure. checked of any weldment on the mechanism beam or the sub frame has crcked.
no improvement. I even crosschecked the CG of the screen.
Changed springs but no improvement.
ALl your suggestions are invited. ■
Screen vibrating all directions
Hii all...... just finished testing a 2000 x 4000mm horizontal vibrating screen. we are driving it using 2 x 5.5 Kw unbalanced motors.
My screen is mounted on 8 identical coil springs. the springs compressed by 55-56mm on loading the screen on them. The machine is in level ( left right and front back also )
The support structures look ok, the screen construction is ok and the whole machine is huck bolted and stiffeners at the right places to keep the machine in shape.
Now the problem is peculiar, While the motors are switched on the screen for a few seconds vibrates fine and then it gets fluttering sidewalls, and unwanted vibrations in all direction. The stroke card cannot be made as its tough to hold a pen against it.
the material on the deck moves 10 steps to the sides of the screen each forward move it makes.
I tried puttin two handful of sand on both corners of the screen feed end and surprisingly the materil moved towards the center of the deck and then scattered here and there.
All i can now make out with the motion is that there is no linear motion atall.
I have checked the direction of rotation of the motors, they are fine. The current cunsumed differs by just 0.1 amps. While the motors stop though i can see that one motor makes atleast 1 rotation after the other one stops completely. I guess the one that stops earlier should be slightly jammed.
I hope i have provided required information.......... i would like to know what could be the possible reasons for such a failure and the corrective actions.
Regards
Sandeep ■