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Bias-Ply tire failure in non-automotive industrial application
5

Bias-Ply tire failure in non-automotive industrial application

Bias-Ply tire failure in non-automotive industrial application

(OP)
I have a "High Spin" rolling system that spins pipe to compact cement lining.  We are using tandem 7-14.5LT D/8 bias-ply tires on each end of the axles with the pipe riding in the saddle between two sets of tires.  The tires are running approx. 70 MPH for just over a min.  The maximum weight of the pipe is 3500 lb. and it is held down with two sets of metal rollers that straddle the pipe with approx. 800 lb of downward force on each set.  
My problem is that we keep separating the tread from the tire.  The pipe thrust one way or another without issue so I am not sure that bias is the proper tire for this application.  Any help would be appreciated.

RE: Bias-Ply tire failure in non-automotive industrial application

Since the radius of the pipe is much smaller than the radius of a road, I'm >>guessing<< that radial ply tires would sustain the abuse of repeated extreme flexing better than do bias-ply tires.

Mike Halloran
Pembroke Pines, FL, USA

RE: Bias-Ply tire failure in non-automotive industrial application

Tyre pressure might also be a very significant factor, like they might need somewhat more than automotive application pressures to cope with the extra distortion at the same load.

Regards

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RE: Bias-Ply tire failure in non-automotive industrial application

You are also running at a speed rather close to wheelhop, I suspect, so you may be exacerbating heat buildup in the tread.

Small rollers at high speed are a good way to wreck tires as Mike said.



Cheers

Greg Locock

SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

RE: Bias-Ply tire failure in non-automotive industrial application

2
Mr. Reliablity,

Did I understand this right, that the combined load on the tires is 4100 pounds?

Also, you didn't tell us the diameter of the pipe.  Maybe I can find a diameter vs deflection graph, so we can estimate what the flat plate equivalent load would be.

And lastly - I tend to think that radials would be worse rather than better.  But just to be on the same page:  The casing is intact, right?  Only the tread is chunking off?

RE: Bias-Ply tire failure in non-automotive industrial application

5100 lbs / 4  No ?

RE: Bias-Ply tire failure in non-automotive industrial application

(OP)
Thanks everyone for your input.  I've had some local "experts" come and look and what they have said is that with higher air pressures there is no 'give' in the sidewalls and so the tread is taking all of the flex, they also said that the tire is slightly narrower than what the rim is made for.  With the small diameter of the tire and the fact that the tandems are tight together I believe that the options are very limited.

CapriRacer,
Yes the combined weight on 8 tires, 4 sets of tandems, is as high as 4100 lbs.
The diameter of the pipe range from 6" to 30" with weights of 30" pipe being around 4100 lbs and 6" pipe being around 500 lbs.
The casing is intact it is just the tread chunking off, on inspection of blown tires you can feel that the tread has seperated completly around the crown of the tire.

RE: Bias-Ply tire failure in non-automotive industrial application

(OP)
Sorry I screwed up. The max weight for 30" pipe and the hold downs is 5100 lbs not 4100 lbs as earlier stated.

RE: Bias-Ply tire failure in non-automotive industrial application

How many of the tandem assemblies are drive wheels?

How is the rotating pipe braked to a stop?

Is there any particular set of tires within which you're experiencing a greater failure rate?  Any one tire position in particular?

Does the end of a tire's life tend to occur at a particular point in a 'spin cycle' or is it random?

The summation of forces applied to any given tire isn't quite as simple as 5100 รท 4 (and likely not quite equally divided in each pair).

I wonder if you're starting to generate standing waves in the treads.


Norm

RE: Bias-Ply tire failure in non-automotive industrial application

Higher air pressure will be distributed evenly and will reduce flex in both the tread and sidewall. Large trucks use 100 psi on their tyres which are heavily loaded. This does not cause their treads to chunk off.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.

RE: Bias-Ply tire failure in non-automotive industrial application

(OP)
Norm
There are 4 axles with the two inside axles being drivers and the outside two are idlers.  I agree that the load will not be the same for all of the tires.  The pipe has a bell on it that is considerably larger, thicker and heavier.  There seems to be no pattern to the chunking.  I am thinking that the small footprint of the pipe and the cengrifugal(tangential) force from the pipe spinning might be a factor.  On one side of the tire there is a footprint and on the other side (30-45 degrees apart) there is another footprint, except for the outside tires.  I thought that the idlers would either go more or less frequently because of this but that is not the case.
As far as standing waves, I don't even know how I could conferm this or not, but the pipe spin according to speeds that were found to better compact the cement and remove the water.  Standing waves could be a contributing factor in this compaction.

Would anyone know how this might be confermed?

I would like to find out about having a 'tire engineer' come out as a consultant.  Does anyone have any information on how to go about getting someone?

Again thanks for everyones comments and help!

RE: Bias-Ply tire failure in non-automotive industrial application


"Would anyone know how this might be confermed?"

Video?  (guessing that you'd want it at a higher speed than consumer camcorders are good to, though)


Norm

RE: Bias-Ply tire failure in non-automotive industrial application

A strobe light might work and would be simpler and cheaper than high speed video.

RE: Bias-Ply tire failure in non-automotive industrial application

I agree with Compoitepro.

An adjustable strobe light is the way to go. You adjust them to get a slow rotation effect similar to the stage coach wheels in old movies.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.

RE: Bias-Ply tire failure in non-automotive industrial application

Mr. Reliability,

First, sorry for the math error - I caught it after I posted - and apparently so did everyone else.  That's what I get for doing this in my head!!!

OK, so 8 tires carrying a total load of 5100 = 638# per tire.

The tire is rated for dualed tires is 1650# at 70 psi.  BTW, what pressure are you running?

I still haven't found a flat plate to curved surface chart, but I do know that a 67" diameter road surface needs to be run at 88% of the load to get the same deflection - and there are some who think that even getting the same deflection generates stresses in excess of the flat plate.

I also don't know if the worst case is the 3500# 30" diameter or the 500# 6" diameter.

Plus I think we need to factor in that the loading on the tire isn't strictly radial.  The net force on the tire is producing a tangential load above and beyond the torque needed to spin the pipe.

If I had to hazard a guess, I think the radial load needs to be half of the rated load.  That would be 825# tire rating vs 638# pipe load.  Still sounds OK, but is the load the same on all 8 tires?  (I think you said the load is unlikely to be the same)

"Too much pressure?" - I totally disagree.  These are bias tires and the fact that you are getting tread separations says there is a shear force that is exceeding the bonding strength between the cords and the rubber.  Lowering the pressure is either going to cause the separation to occur sooner or the separation will occur in the sidewall.

Oh, and how old are these tires?  Is it possible that what you are seeing is just tire age?  Maybe a bit of history would help.  Which tires failed?  Have there been repeats?

BTW, I would hope you are at least replacing tires in pairs.

How about a photo?  It is hard to visualize what the set up is and those of us who know tires and what is important to them are going to look for certain things - and those things will be different that what a machinery guy would be interested in.

One last thought.  I'll bet the shop has an infared pyrometer.  You could measure the tread surface of the tire.  That will tell you lots about the actual loading.

RE: Bias-Ply tire failure in non-automotive industrial application

Post Script:

Where is my head this morning????  I forgot the simplest test of all - pressure build up!!!!

Measure the inflation pressure cold - the machine has to be idle for at least and hour and a half - longer would be better.

Then measure the pressure after an hour of operation - and every hour until the pressure stabilizes.

This is a little out of my league (I'm a passenger tire guy), but I think you shouldn't see more than a 5 psi build up.  If more than you need to add pressure.

RE: Bias-Ply tire failure in non-automotive industrial application

(OP)
CapriRacer,
To answer a couple of your questions:
We were running unloaded pressure of 70psi we have since changed it to 45psi.
All of the tires are within 6 wks old when they blow, and we are changing at least both tires in a tandem, most of the time we are changing all 4 tires on an axle as we have to pull the axle to change a tire due to clearance issues.
There seems to be no rhyme nor reason to the blow-outs. They are spread out.
I have attached a picture of the high spin rolls in action.  This is an 8" pipe.

RE: Bias-Ply tire failure in non-automotive industrial application

If the radii of the tyres on a car differ slightly it causes the car to turn (then corrected by steering) or for the play to be taken up by a differential.

If your tyres had different sizes due to different starting pressures, different heating, a recently shreaded worn tyre being replaced by a larger intact new one, or whatever, is there anything like turning or a differential that absorbs the speed difference [same shaft angular velocity times different radius gives a different desired speed], or does it result in a torque between the contact patch and the wheel that almost literally has nowhere else to go apart from slip and eventual damage?

I hope I'm making sense. I understand what I'm trying to say, but I haven't written it very eloquently!

RE: Bias-Ply tire failure in non-automotive industrial application

Is that three pipes loaded into the gaps in four tyres, so tht the inner wheels support two pipes and the outer wheels support just one.

If so, can the outer shafts and wheels that support one bar spin at a different rate to the inner ones that support two?
Or are all the shafts driven from the same source 'with no play in the system'.

I'm coming back to my previous posting. I should have looked at the picture first, but I have a slow modem where am I now.

RE: Bias-Ply tire failure in non-automotive industrial application

Mr. Reliability,

I think I now see why the lower pressure was recommended.

It looks like there would be an incredible amount of shear stress in the tread area - and there are opposing shear forces - something a tire would not ordinarily experience.

I am curious.  Is this an old machine?  If so, what changed? (unless you were having trouble before and this is just a continuation.)

RE: Bias-Ply tire failure in non-automotive industrial application

(OP)
crystal1clear,
Yes there is 3 pipe, on smaller sizes, on 4 axles.  The outside axles are idlers so they are independant.  We do not have any problem with the tires slipping.  The tires are replaced as a tandem or an entire axle.
CapriRacer,
This is a brand-new piece of equipment.  The old equipment had steel wheels on the bottom and radial tires that came down from the top.  The large steel wheels caused millions of dollars worth of damage, due to high-spin fractures that could only be found after installation.  This is an engineered piece of equipment and the only one in the world so nobody knows anything about it.  A ME designed and built it but he has little to no experience in tires.  Just by calculating the load is how he determined the tire.

RE: Bias-Ply tire failure in non-automotive industrial application

Mr. Reliability,

Thanks for the info.  On the previous piece of equipment, what size were the radial tires and how much load was applied to them?  In other words, I am wondering if there is enough load carring capacity.

RE: Bias-Ply tire failure in non-automotive industrial application

Could you replace the wheel tyre combination with solid rubber or solid polyurethane tyres on heavy steel wheels. This would still give some, but much reduced compliance under load.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.

RE: Bias-Ply tire failure in non-automotive industrial application

Pat mentioned 100 psi on trucks.

If I've got this right, failure is occurring often enough and without damage (other than the tyres), so experimenting to find a better setup seems reasonable to me. My paragliding teacher used to design his own shutes and there failure is critical - so his approach was to make marginal changes in design and to keep them if they made an improvement. If you can't make bold changes as a test, you could make incremental changes and look at the effect statistically to see if there are improvements.

Tyres are convex. Where they meet the road the road forces the shape to be flat: the inner and outer radius of curvature at the contact patch is effectively infinite. It seems to me that what the pipes are trying to do is make the tyres buckle inwards at the contact patch.

I assume that inward buckling is beyond what the tyres are designed for. CapriRacer seems to be the man in the know - the tyre expert.

The inward buckling would be reduced by higher tyre pressures. On the other hand there is the driving force at the contact patch which is trying to shear the tread off tyre. The purpose of dropping the pressure from 70 psi to 45 psi might have been to increase the size of the contact patch and therefore reduce this shearing force on any square inch of the contact patch.

On a safety note, are workers well clear of the machine when it is in operation? If tyre failure was considered unlikely when the machine was designed and is now a common occurence in operation ... ugh.

We haven't mentioned horsepower. Are the pipes brutally brought up to speed to get the job done as fast as possible, or gently spun up to speed? If the spin-up time is short, ie the motor is very powerful, can this be done slower, as a test.

The same for stopping. Is the motor turned off or gently brought back down from running power to zero?

On Pat's point about solid rubber tyres, I believe the reason we have air in tyres is passenger comfort on undulating surfaces. You have neither passengers nor undulating surfaces. I'm no tyre expert; these are just my thoughts.

If increasing tyre pressure causes failure due to more shearing on a smaller contact patch, and lowering pressures causes failure due to the tyres buckling inwards, then I'd be tempted to say the curvature of the pipes (compared to the flatness of a road) is the cause of the problem and I'd wonder if using more wheels would be a solution.

There are no strange chemicals coming into contact with the tyres are there? THey aren't getting covered with cement dust or whatever. [Not that I would expect cement dust to influence tyres. I just ask so that we can eliminate chemical attack as a possible cause.]

Sorry for the disjointed nature of this posting - I am being pestered to go an eat!

RE: Bias-Ply tire failure in non-automotive industrial application

I am entirely onboard with Chrystal's analysis.

A pnuematic tire has more ability to absorb shock loads than a solid rubber tire - and I think this was the point of going this direction.

I wasn't considering the horsepower - and I think that may be significant particularly in view of the shear forces at the tread face.

I also think a radial tire might be worse.  I can imagine that a radial would be more compliant for rotational shock loads - starting and stopping the spinning.  But I don't think that is the issue here. But a very real side issue would be when a failure occurs.  A bias tire will throw chunks off the tread, but a radial generally throws the entire tread as more or less a unit - and while it is coming off, it will flap around damaging anything within distance.  

One last thought:

It is common for there to be tire chunking problems when new cars are tested on dynamometers - mostly during the braking portion at the end of the test. Coasting basically eliminates the problem.

My gut tells me Chrystal hit the nail on the head mentioning this.  Go there first!  

RE: Bias-Ply tire failure in non-automotive industrial application

My 2 cents,
 Have you ever operated this unit for an extended time with no pipe smaller than say 20"-24" ?  looking at the picture i can see where it may have trouble with smaller diameters.
   I am on the high side of the air pressure debate.
 Unfortunately the issues i see and every  factor discussed  so far would seem to argue for at least some increased failure rate of the center tires ?
      Good luck

RE: Bias-Ply tire failure in non-automotive industrial application

Measuring the peak and typical operating temperature of each tyre might yield useful information.

Is the mould in balance before the spin up, or is the purpose of the spin up to distribute the concrete evenly. I imagine that the concrete is all on the bottom at the start and the spin distributes it. In this case, initial acceleration rate will be critical to reduce dynamic load from imbalance.

If it is only the small dia pipes that cause the problem, maybe the outside of the mould could be made larger with some sort of wheel that slides over the mould, or like one pipe inside another, held concentric with spacers.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.

RE: Bias-Ply tire failure in non-automotive industrial application

You probably have two or three issues that are working together to cause the problem.
1. The steel mold tends to act as a wedge between two opposing tires. If you write the statics equations for this situation, you will find that the vertical component of the load is transmitted to the tire as a radial load. This essentially amplifies the load. I estimate the amplification factor is about 1.6 for the 8 inch mold.
2. 70 mph sounds high for this type of application. At these speeds, you probably have a good bit of dynamic load that adds to the situation.
3. You may also be overloading the tire from a torque perspective.



www.forsytheandlong.com

RE: Bias-Ply tire failure in non-automotive industrial application

Shout out for Mr. Reliability!!!

What's going on?  What's happened!!  

I see this as a learning opportunity and would be really interested in a progress report.

BTW, on the TV show "Modern Marvels", they showed a similar machine that was used to build the support columns for the trestle part of the Chesapeake Bay Bridge /Tunnel.  They claimed the pipes were spinning at 60 mph and it sounded like they spun for 45 minutes at that speed.

RE: Bias-Ply tire failure in non-automotive industrial application

(OP)
Sorry for disapearing.  My plant had a major explosion and I have spent the last month and a half helping to rebuild it.  We have just made our first pipe today so things, hopefully, will slowly return to normal.  Needless to say this suddenly became a low priority for the plant.  I have also talked with a PhD.'s at one of the local universities and he thought that contact sresses sound like it might be one of the root causes.  I started calculations on the tangential forces applied and thought I was on the right track but he thinks that I might be spinning my wheels, pun intended.  It turns out that the Dean of Mechanical Engineering at the University of Utah is an expert in tire failure analysis, go figure there would be someone in my own back yard.  Apparently he has worked with a number of the tire manufacturers.  I am going to try to contract him as a consultant, but your feedback is still appreciated and I intend to provide him with all of your helpful information.  Please don't stop your recommendations if you have any other ideas, I still find them to be extremely helpful.

RE: Bias-Ply tire failure in non-automotive industrial application

(OP)
Well it turns out that the Expert that I thought I found thinks that it is out of his area of expertise. I am really needing help here so if anyone is interested or knows someone who might want to consult on this I would really like to find someone.
I am going to go back to crunching numbers, unfortunatly this is not my best area I am more of a design/concept idea engineer.  Any help would still be greatly appreciated.

If I have forgotton to answer any questions that were posed please remind me as I have been pretty preoccupied with the plant explosion lately.

RE: Bias-Ply tire failure in non-automotive industrial application

I just looked at the picture you posted again and I find it interesting that one can see wear marks on the pipe where it contacts the tires but no marks where they contact the steel rollers. That seems strange. Also the wear marks seem to be much narrower than the tire tread and at center of the tread which is where you say separation starts.

Have you tried any radial belted tires? Bias ply tires have a round pressure carcass with a cap on top to provide a relatively flat tread. The radial belts in radials might provide more uniforn contact pressure and distribute the shear load between the pipe and the belt over a larger contact area.

However, if the failures are due to excessive flexing of the tread then radials might be worse.

Are you sure the tires are aligned properly? I see there are rollers at the ends of the pipe to keep them from walking-off axially. That's okay as long as that is not concealing an misalignment problem. The load on the end rollers should be quite small.

RE: Bias-Ply tire failure in non-automotive industrial application

Mr. Reliability,

I just read over all the posts, and where I think we left it was the speed and cycle time.

Can you give us a primer on the actual operation cycle?

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