We are in Steel Mill with problem of Rolling Mill Chatter. The arrangement of the drive train is Motor+Gearbox+spindle+Top/Bottom work roll.

The problem is when rolling light gage (1.55 mm) strip we always got high vibration in mill stand and chatter mark 40-50 marks on work roll, the data from Edas Roll Force FT shows frequency band around 40 to 50 with side band 1xwork roll, we called chatter frequency.

We observe that when mill light gate (2mm) there is no chatter frequency in Roll Force FT but the chatter frequency start in HGC Servo Valve FT and then step down to mill light gate 1.55 mm, the chatter frequency start in Roll Force FT after that the roll were marked.

We alredy change new sevo valve by swith with back up the problems still occur.
Did anyone in steel mill facing this problem, please share.

Cheers.
Phoo.

The work roll frequency around 1 Hz.I had checked no frequency of Gear Mesh, Bearing or dive motor exciting.

quote:

We observe that when mill light gate (2mm) there is no chatter frequency in Roll Force FT but the chatter frequency start in HGC Servo Valve FT and then step down to mill light gate 1.55 mm, the chatter frequency start in Roll Force FT after that the roll were marked.

I wish I understood the "steel mill" terminology. Can you explain a little better in layman's language what is happening.

The "HGC"? The "Roll Force FT"? "Stepdown to mill light gate"?

A picture might help.
what drives the rolls? Has this ever happened before?

I'm in a rolling mill myself although different somewhat. You should make a lot of checks. I assume your backup roll is twice the diameter of the work roll and driven by hydraulics. The hydraulics OK? It does this re 1X regardless of running speed and/or reduction? Unable to find bearing frequencies? And, what about chatter marks on the plate? As I understand you're saying, "marks are on the work roll" - is this correct?

Hi Phoo,
You may find the description of various chatter phenomenon in the vibration magazine march 2006, volume 22, number 1 publish by the Vibration Institute.

Best regard, Marcel

Ralph, I am preparing diagram of mill stand drive for you.

Sam,What's minimum thickness you can mill, Did you have this experience in your plant when mill light gage strip. I got chatter both on work roll and the strip, the plate did you mean the plate that support load cell?

Marcel
Could you please share chatter phenomenon paper to me.

Thanks
Phoo

We do plate and rolling stock varying to 0.015" or less with a lot in the 1/8 1/4 range.

Phoo

What is the width of the chatter marks? What is the speed of the mill at the time of chatter?

Please file attached for detail of chatter problem, your input will be appreciated.

Thanks
Phoo

Mill_Stand_Drive.ppt (130 Kb, 35 downloads)

Please see attached file and input your comment.

Thanks
Phoo

Mill_Stand_Drive.ppt (65 Kb, 30 downloads)

Hi Phoo,
Sorry about the quality of the document. I just couldn't do any better. Hope it will help a bit. Personnaly i know notting about rolling mill.

Best regard, Marcel

chatter.pdf (178 Kb, 28 downloads)

quote:

The problem is when rolling light gage (1.55 mm) strip we always got high vibration in mill stand where exactly is the mill stand in the drawing and where is the data taken? and chatter mark 40-50 marks on work roll, On the work roll itself or on the sheet of steel? the data from Edas Roll Force FT shows frequency band around 40 to 50 with side band 1xwork roll, we called chatter frequency.are the work rolls "marked" with "barring" ridges on them?

What are the units the data you posted stored in?

Where was the data actually taken from (position) in relation to the "rolls"?

Are the "work rolls" not supported on the non drive end?

Are the "work rolls" the same diameter? Coming out of the same gearbox might force them to have to be, huh?

What are their diameters?

What are the spacing of the chatter marks?

The data area you have "circled" appears to have 2 different "carrier frequencies" rather than just one.

Only my opinion and I could be totally wrong.

If you are still experiencing issues with chatter at your mill please contact Mr. Bob Miller @ IVC (800) 525-1269. Bob specializes in hot/cold mill chatter and process problems. He may be able to assist you with your problem.

Jim Smith
IVC

Trying to solve the problem as per attached file.

Thanks
Phoo

May_Coordinated_application_of_Roll_Gap_Lubrication_Work_roll_cooling_and_Antipeeling_systems_in_HRM_(2).pdf (19 Kb, 32 downloads)

Hope that you figured things out. If you are still having chatter issues you could bounce over the PDA "dat" file and I'd be happy to take a look and see if I can help. I deal with a lot of chatter on a lot of different hot and cold mills from the vibe and control side so I may be able to figure something out.

Best regards,

Bob Miller