Re: Twin Spring Function For Screen
rfiremam,
Although it is not desirable, screens in some special extra heavy duty applications have to endure occasional very high impact loads of falling material.
To select a spring to withstand these intermittent high loads would mean that it would need to be very stiff (with a high k value) resulting in poor isolation properties when the screen is running normally. A solution to this problem is to fit a set of shorter inner springs (with an air gap).
So now while the screen is running normally the load only acts on the outer springs which provide good isolation. When the occasional heavy impact load is applied the outer springs will compress until the second inner spring share the load, and acting together they provide sufficient stiffness. ■
Re: Twin Spring Function For Screen
John,
Thank you very much for explanation. I will consider outer spring stiffness for normal operations. It will provide better isolation and less forces transmitted to structural steel.
Regards ■
Large Amplitude During Stop
Meanwhile you will have large amplitude during stoppage which may your small springs engage.
So I recommend you check your structure during screen stop which screen pass resonance and loads become 5-6 times. ■
Re: Twin Spring Function For Screen
Hello,
The twin springs mentioned by you are selected for following reasons:
1) To get more stiffness of the spring-unit, within given space.
2) In the event of failure of one spring, the other spring will prevent immediate damage to the equipment (obviously, one has to replace the failed spring immediately, unless equipment design permits operation for some hours / days, etc.).
3) Such twin springs are also used, when requirement of deflection resisting force is greater than proportionate to deflection of combined unit, after certain deflection of the spring-unit. This is achieved by having inner spring of somewhat shorter length.
Regards,
Ishwar G. Mulani
Author of Book: Engineering Science And Application Design For Belt Conveyors (new print November, 2012)
Author of Book: Belt Feeder Design And Hopper Bin Silo
Advisor / Consultant for Bulk Material Handling System & Issues.
Pune, India.
Tel.: 0091 (0)20 25871916
Email: conveyor.ishwar.mulani@gmail.com
Website: www.conveyor.ishwarmulani.com ■
Twin Spring Function for Screen
Hi,
I need some advise on function of twin springs in a screen.
Let me explain my case;
I am a engineer and working on to provide a support steel for a 10x16 ft screen. it is supported on 16 springs (4 at each corner). Each corner has combination of 2 twin springs. combination of twin springs is such that smaller spring is inside of larger spring. smaller spring is 3'' smaller in length and similarly smaller in diameter. I could not understand the function of a smaller spring. In my opinion all LOAD will be taken care of larger spring and smaller spring will not see load. Is smaller spring is for safety.
I need to calculate spring K and natural frequency for mass spring system. Do I need to consider smaller springs in my calculation. There is a 50% difference in K for 8 springs as compared to 16 springs. Please advise and help me in this regard.
Thanks
Added by Moderator:
Example of Vibrating Screen ■