Steel Tube Bending: Gai Abraham's LEV Automotive Engineering Question

  • Thread starter Thread starter ga5aq
  • Start date Start date
  • Tags Tags
    Bending Steel
AI Thread Summary
Gai Abraham is seeking advice on bending steel tubes for a low emission vehicle chassis, specifically regarding the definition of the original length during bending. He questions whether the original length should be considered as the midline of the tube or the inside radius, given the compression and tension experienced during the bending process. Suggestions include using sand to fill the tube for added support during bending and exploring resources on tubing fabrication. Gai has modeled a 90-degree bending radius in AutoCAD and is concerned about exceeding elongation limits, which could lead to cracking. He aims to finalize his material choice before proceeding with production.
ga5aq
Messages
3
Reaction score
0
My name is Gai Abraham, an automotive engineer trying to build a little LEV (low emission vehicle)

I have contacted you previously and I wish to ask further help on the bending of steel tubes.

Namely I have designed a chassis from bent steel tube, the technical sheet on S.S. astm 301 allows, depending on the hardness of the tube, to have elongations ranging from 40% (for annealed) up to 9% (for full hard) from original length.

The issue I am trying to solve is whether the original length is the midline of the tube, giving during bending, compression on the inlay and tension on the outlay for final plastic bending

or the original length is the inside radius of the curved tube and gradually all the tube stands deformation up to a maximum value on the outer side?

I think that if the tube is held in position and supported on the inside while curving it, the original length is the inside radius since it was not able to compress.

thank you
Gai
ga5aq@yahoo.com
 
Engineering news on Phys.org
I got to ask: How would you support the inside of the tube? If you could do that, you are correct in saying the inner radius would be the length. But, I've never seen anything even close to that.
 
Uhm
that's the real question, I don't really know how the bending machine works, I guess that there is a concave roller on either side of the tube and the roller turns on a radious predefined supporting the inner tube while the outer roller goes on bending it on the outside.

what's your e-mail add?

Cheers
Gai
 
An old trick to consider, is to fill the tube with sand, pack it as tight as possible, plug both ends,( you might need to have a pair of plugs machined, kind of like thermos bottle stoppers) this will make the tube almost as solid as a rod. After bending the end plugs are removed and the sand will pour out.
 
Probably for your application, I'd suggest you go to the Pirate4X4 website and find tubing fabrication hints.
 
thank you all
as I will try to take this Lev to production I am hoping to use the Stainless steel ASTM 301 in its 1/2 or 3/4 hard modes.

the limit of bending of these two is bound by the percentage of longation so if I use a too small a radius I might crack it.

on the autocad program I have modeled the bending radius of 90 deg. and I have found that if I take the values of the inner radius and th outermost radius of the bent I am out of the elongation percentage stated but if I use the midline, then I pretty close.

as such I was wondering if the tube is being supported from the inside, then the midline stretches and the outer line stretches even more, on the other hand I might just as well take the midline as being stable i.e. original lebngth, and on either side I have got a compression and an extension.
but as I don't want to buy a stock load of steell tubes of one grade to then find out it doesn't cope with bending I thought to hear some views about it.

BTW I like it the PIRATE 4X4 stuff, Thanks TVP45
 

Thread 'Query on Isentropic relationships (such as PV^gamma = constant)'

Hi all, I have a question. So from the derivation of the Isentropic process relationship PV^gamma = constant, there is a step dW = PdV, which can only be said for quasi-equilibrium (or reversible) processes. As such I believe PV^gamma = constant (and the family of equations) should not be applicable to just adiabatic processes? Ie, it should be applicable only for adiabatic + reversible = isentropic processes? However, I've seen couple of online notes/books, and...
View full post »
Thread 'How can I find the cleanout for my building drain?'

Thread 'How can I find the cleanout for my building drain?'

I am a long distance truck driver, but I recently completed a plumbing program with Stratford Career Institute. In the chapter of my textbook Repairing DWV Systems, the author says that if there is a clog in the building drain, one can clear out the clog by using a snake augur or maybe some other type of tool into the cleanout for the building drain. The author said that the cleanout for the building drain is usually near the stack. I live in a duplex townhouse. Just out of curiosity, I...
View full post »

Thread 'Dry sump pump issue'

I have an engine that uses a dry sump oiling system. The oil collection pan has three AN fittings to use for scavenging. Two of the fittings are approximately on the same level, the third is about 1/2 to 3/4 inch higher than the other two. The system ran for years with no problem using a three stage pump (one pressure and two scavenge stages). The two scavenge stages were connected at times to any two of the three AN fittings on the tank. Recently I tried an upgrade to a four stage pump...
View full post »

Hot Threads

Recent Insights

Back
Top