Structure Supporting Jaw Crusher 3

[zetmech]

I have a new Jaw Crusher and its Grizzler installed in our plant. In trying to run the jaw crusher and the grizzler feeding the jaw crusher I am having a very big problem of vibrations on structures which are very abnormal. I suspect structureal issues supporting the grizzler and the jaw crusher to be the problem associated with these vibrations. Can anyone assist in the the way in which structural issues can cause severe vibration problems when supporting crushers.

 

[bootlegend]

zetmech,

Are you talking about a structure that is already erected that is experiencing vibration problems? Or are you designing the structure and having problems with vibrations in your model?

 

[hokie66]

Those things shake like hell, and require heavy structure. You need an industrial structural engineer to do an analysis. Do you have any kind of vibration isolation installed?

 

[TLHS]

Was your foundation engineered? Ask the engineer what they did. Usually you'd put some significant mass under something like that to reduce vibration.

 

[spieng89]

When I designed foundations for industrial lumber facilities we typically designed the foundations with a mass 5 times the vibrating machinery mass if it rotated and 3 times for lateral movement machinery. Any less and we had history of running into vibration issues. Also as Hokie noted if possible isolate these foundations from other foundations as the vibration will be transmitted through.

 

[3DDave]

I second vibration isolation.

 

[Hoxton]

In the old times large Diesel engines in power stations (5000 kW 600 rpm) were bolted to a concrete base that was separated from the rest of the foundation by rubber slabs.

Now I know why!

 

[WARose]

You may want to get with the structural engineer and ask him what (if anything) he did to account for the unbalanced loads.

There are a few companys that handle this that I can recommend if you want.

 

[hokie66]

Unlike others here, I assumed the crusher and grizzly screen are supported at an upper level in a steel framed preparation plant. The mass solution of providing a big concrete block is not often practical in that situation.

 

[TLHS]

In that situation, some vibration is generally unavoidable, but you should look at isolating the equipment, and look at ensuring that the equipment support steel is separated from the other building steel.

 

[saplanti]

In case the vibration forcing frequencies of the crusher matches the natural frequencies of the structure you will expect resonance, it will results with large uncontrolled displacement, and stresses. it may even see total destruction of the system. You need to employ a specialist structural engineer to go through the natural frequencies and provide adequate stiffness in the structural system not to cause the resonance.

If this is the new process you will need to check above. If this happens on the existing and long time working plant, you need to check the structure against the drawings for the missing members or failed connections. Additionally I would suggest you to check the crusher connections onto the structure.

 

[Tmoose]

Could you spare a few pictures of the installation ?

 

[WARose]

When I designed foundations for industrial lumber facilities we typically designed the foundations with a mass 5 times the vibrating machinery mass if it rotated and 3 times for lateral movement machinery. Any less and we had history of running into vibration issues.

I'll say this for zetmech's benefit: Be careful with this. I've run into a number of situations where this was not adequate. (Several in fact where issues had to be addressed after construction.) It is a good starting point for design......BUT.....it doesn't guarantee the performance you want.

If the guy who did your design addressed the situation only by doing that (in lieu of a dynamic analysis)......that may be where it went wrong.

 

[WARose]

By the way, if you need a consultant zetmech, a few companies I would recommend:

--(If you are in the southeast, and sometimes elsewhere): Southeast Dynamic Loading, LLC (See their website @

http://www.sedynamic.com).

They specifically handle (structural) issues like this.

--A national chain: VACC, Inc (See their website @

http://www.va-consult.com/cat_services.html)

They've got some outstanding equipment. I've worked with them before.