bike tubing-how do they do that?
Jim Papadopoulos
Whittle) wrote:
> So how do they make bike tubing? I assume it is cold drawn, but then how
> do they make butted tubing? Is it a variable die, or is it drawn at a
different
> rate, or what?
>
> A collegue is intending to include this in a talk on friday so any replies
> would be met with much sickly sweet gratitude!!
>
1. Call up directory assistance for Birmingham
2. Ask for TI..... Oh never mind.
Here's my speculation, if I'm wrong I'd love to know why.
The tube is drawn with variable diameter mandrel inside (short piece only?
or a long one destined to make many top tubes???)
To get out the tightly stuck mandrel, they need to thin the metal which was
drawn over it, by tangential strain. Obviously, if you can roll the tube wall
thinner, its diameter will grow. Then the mandrel will fall out.....
JP
Jeff Bernhard
[Deletia]
:
: A solid, hot log of steel is pierced by a sharp poker to make it a thick
: walled tube. The thick-walled tube is then pulled through
: dies to make it smaller in OD, but longer. A series of operations like
: this follow: a mandrel that tapers like the evetual butted inside shape
: of the tube is placed inside the tube, and the tube is drawn through a
: circular die that squeezed down the OD of the tube, squishing the ID against
: the mandrel.
:
: The tube is then bent a wee bit and the mandrel pops out.
: This process is repeated several times with deeper butting each time,
: with the OD decreasing each time, and the butt getting more extreme each
: time. Only small changes are made with each step. Too big a change in
: a given step, and the material would fail, or the mandrel wouldn't pop
: out.
[Deletia]
:
: Olsen
I'm missing something. How is double butting done? Once one side is butted
as above, how can the other side be butted with a mandrel and the mandrel
extracted?
--
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Curt Austin
> dwh...@liverpool.ac.uk (Mr D.M.Whittle) wrote:
> > So how do they make bike tubing?
> To get out the tightly stuck mandrel, they need to thin the metal which was
> drawn over it, by tangential strain. Obviously, if you can roll the tube wall
> thinner, its diameter will grow. Then the mandrel will fall out.....
>
> JP
I was once told by a metallurgist that it does involve a mandrel with a
tapered shape. The mandrel is removed by twisting the tube. I don't know
if the twisting must plastically deform the tube, or if elastic
deformation is sufficient to increase the diameter and let the mandrel
fall out.
--
Curt Austin
Gary Helfrich
: I'm missing something. How is double butting done? Once one side is butted
: as above, how can the other side be butted with a mandrel and the mandrel
: extracted?
: --
Well, this is one way that it is done. (This is from watching the machine
work at the mill) A tube that is slightly larger than the tube you are
intending to end up with is slipped over an inside mandrel, which is
shaped the same as the inside diameter of the tube you want to end up
with. The tube, along with the mandrel are drawn through a sinking die,
reducing the tube to the finished diameter in the process. O.K., you ask,
how do you get this chunk 'o steel out of the tube? Well, in the old
days, (Except for a certain British company, where tommorrow is the past)
you would just yank the mandrel out. As long as this did not push the
other end of the tube past its yield point, it worked fine. Looks like a
snake puking up its dinner.
This method has some severe limitations as to final sizes and
differentials that can be achieved. Higher performance tubing is drawn
twice. The first step is the same as described above, but the end of the
tube where the mandrel is extracted ends up fishmouthed, due to the more
radical shape of the internal mandrel. This tube is then run through
another sinking operation, but with nothing inside, which squashes the
flared end back down.
There are also continous methods like the one that True Temper uses. In
this process, the tubing is butted as it is drawn. There are also
methods used in butting titanium, where the tube is machined, and then
redrawn, or etched and forged. Lots of ways to skin a cat, as they say.
Gary Helfrich
Arctos Machine
Jim Papadopoulos
> you would just yank the mandrel out. As long as this did not push the
> other end of the tube past its yield point, it worked fine.
In search of wisdom here..... If a material has a yield strength of 90 ksi
(note, in a drawn tube transverse yield stress might be fairly low) then
it can be stretched elastically by 0.3 percent, without yielding.
In a butted 1" tube, this means an expansion of 0.003".
Isn't the differential between butts and center section greater than that?
(I don't have any books handy...)
Well, either the tube is already pretty loose on the mandrel after drawing
(unexpected but plausible)
Or it gets enlarged by withdrawing mandrel but then is re-sized (never
heard of this)
OR another method is used, the Top Tubes brochure spoke of
'passing between rotating tapered rollers' or some such imperial stuff.
In this last case the only interpretation that makes sense to me
is the one I posted -- the whole tube is enlarged in diameter by (say) 2%
through plastic deformation......
Any further thoughts??
JP
Ericdw
and you have to yank out the mandrel and turn it at the same time which is
really cool.
Eric
Dominic Richens
In article <jjp8-20029...@128.84.141.164>, jj...@cornell.edu (Jim Papadopoulos) writes:
! In search of wisdom here..... If a material has a yield strength of 90 ksi
! (note, in a drawn tube transverse yield stress might be fairly low) then
! it can be stretched elastically by 0.3 percent, without yielding.
!
! In a butted 1" tube, this means an expansion of 0.003".
!
! Isn't the differential between butts and center section greater than that?
Doesn't all this forming take place while the metal is heated to like a
gazillion degrees, when the tubing as malliable as lead?
BTW: I know nothing about metallurgy.
--
!@$^&*)($#$@!@#$^&*()_+_)(*&^$#@!$^&*()_+)(*&^$#@$^&*+_(*&^$#@#^&*()&*$#@(*&+_$
Dominic Richens : dom...@sce.carleton.ca : Tel. (613) 788 2600 ext. 4382
http://www.dgp.utoronto.ca/people/DominicRichens/richens.html
"There are 70 billion people in the world, where are they hiding?"
James W Gourgoutis
thread, there is an article in the 1992 Bridgestone catalog (I think--it
could be the '94) describing how butted tubes are made.
Regards,
Jim
. . . .
james gourgoutis [sko...@pitt.edu] (bob#3068) ~~ ,o "why am I so late?
graduate school of mechanical engineering ~~ -\<, --couldn't decide
university of pittsburgh / pittsburgh, pa ~~ ( )/( ) which bike to ride!"
Gary Helfrich
: In search of wisdom here..... If a material has a yield strength of 90 ksi
: (note, in a drawn tube transverse yield stress might be fairly low) then
: it can be stretched elastically by 0.3 percent, without yielding.
: In a butted 1" tube, this means an expansion of 0.003".
: Isn't the differential between butts and center section greater than that?
: (I don't have any books handy...)
There is significant springback in most metal forming operations. Sure,
the tube is pressing tightly against the mandrel while it is in the
machine, but the tube will expand slightly as it leaves the die.
I'm sure that your figures are correct, but try something a bit more
empirical: Take a rod that is, say, .008 bigger than the id of the tube,
and press it into the tube. Yank it out, and measure the tube, and you
will find that the dimensions of the tube are unchanged.
Remember that butt differentials seem to be like mass measurements taken
close to Morgan Hill, CA. (Where some gravity anomaly causes parts to
actually be as light as they are in the catalog) Tubes seem to never
have butt differentials as large as those published.
Gary Helfrich
Arctos Machine
Ericdw
least cool enough to touch.
I played with some figures and came up with this (metallurgy students, all
six of you, this will be on the final)
With the assumption of a 90ksi steel we can get 0.03% (strain at the
elastic limit. With a SL tube of 25.4mm OD and 23.4mm ID (1mm wall) that
gives an internal circumference of 73.5mm. Applying the 0.03% strain means
2.2mm of allowable deformation. The largest diameter the tube ID can be is
(79mm/pi) 24.1mm. This means a wall thickness of ((24.1-23.4)/2) 0.35mm.
So there we have it, elastic deformation rules since most tubes are butted
only 0.2mm.
Please check my math and flame me if I screwed up. I did this kind of
late.
Eric
Big enough for the
Cyberride
twisting is not typically how it is removed. The material is drawn over
the mandrel at a high temperature and the segments are cut off the mandrel
when the length is sufficient. This process does affect all structural
properties of the materials.
Doug Shelton
Jim Papadopoulos
> With the assumption of a 90ksi steel we can get 0.03% (strain at the
> elastic limit.
0.3%
With a SL tube of 25.4mm OD and 23.4mm ID (1mm wall) that
> gives an internal circumference of 73.5mm. Applying the 0.03% strain means
> 2.2mm of allowable deformation. The largest diameter the tube ID can be is
> (79mm/pi) 24.1mm. This means a wall thickness of ((24.1-23.4)/2) 0.35mm.
0.3% strain on a diameter of 23.4 mm is 0.07 mm. A butt of 0.2 mm implies
a stress of about 270 ksi if the tube fit tightly.
>
> So there we have it, elastic deformation rules since most tubes are butted
> only 0.2mm.
JP
Gary Helfrich
: I would like to vouch for the correctness of the reply by Curt. However,
Doug: What is the source for your information? What do you mean by
"high tempuratures". I have never seen material heated to remove the
mandrel. Generally, an effort is made to keep the material cool with
lubricants.
Gary Helfrich
Arctos Machine
Ericdw
late. The elastic modulus of steel is generally taken as 3E7 or 30,000,000
psi. From that we can only get 0.003% engineering strain from the tube
while still being elastic. I guess the tube must deform plastically. My
appologies to Curt.
Also, cold work can occur at any temperature below which recovery and
recrystalliztion can occur (figure about 900 degrees F, taken from Steels
by George Krauss, ASM books). I t is very easy to keep a tube of any size
that cool during drawing.
And one more uselsess factoid, the rotating drums used to roll a tube to
size are called a Senzer Mill I think.
Again major oops.
Eric
Chris Pastore
>Gerty) wrote:
>
>>
>> I don't need to remove weight from my bike, I need to remove weight from me.
>> So why should I pay extra for the light frame, when I can loose more than the
>> total weight of the bike for free?
Because there is a limit to the amount of weight you can remove from
yourself. After that minimum value, you need to remove weight elsewhere.
--
Chris Pastore |When space doesn't exist, having somebody
NC State Univ. |unpleasant like Mr. Pber^t Pber^d underfoot all
919 515 6572 |the time is the most irritating thing.
chris_...@ncsu.edu | -- Italo Calvino
David R Gerty
>From: dge...@draper.com (David R Gerty)
>Subject: Re: bike tubing-how do they do that?
>Date: Wed, 1 Mar 1995 18:07:44 GMT
>In article <3ih3nn$2...@newsbf02.news.aol.com> eri...@aol.com (Ericdw) writes:
>>From: eri...@aol.com (Ericdw)
>>Subject: Re: bike tubing-how do they do that?
>>Date: 22 Feb 1995 23:42:31 -0500
>>Ok Sorry. I blew it. I warned everyone that I did my calculation very
>>late. The elastic modulus of steel is generally taken as 3E7 or 30,000,000
>>psi. From that we can only get 0.003% engineering strain from the tube
>>Again major oops.
>>Eric
>1% = 0.01
>0.003% = 0.00003
>0.000,03 x 30,000,000 = 9000
I meant 900.
(Oops, wrong time to bump the mouse. Posted by accident.)
Well, if you're looking at 90,000 psi, as I think you intended, that comes to
a strain of 0.003 in/in, or 0.3%. It still isn't much.
Your point, if not your arithmetic, was valid. The tube will distort when the
mandrel is removed. The tube will have to be sized after the mandrel is
removed.
Jim Papadopoulos
>
> I don't need to remove weight from my bike, I need to remove weight from me.
> So why should I pay extra for the light frame, when I can loose more than the
> total weight of the bike for free?
Shhh! Don't say that, you'll be thrown out of the temple!
JP
Matt Bushore
It depends on what kind of riding you are doing. If you can lose more
weight off your body than you can by buying a new frame, then great.
I don't think that I can. [Jim's seen me, he knows I'm but a wisp]
I _can_ tell a difference in weights of bikes, and I would have to
give the nod to lighter bikes.
I am also going to claim that the entire weight of the frame is
unsprung mass, whereas the typical potbelly is sprung mass. Good vehicle
design usually seeks to minimize the unsprung mass.....
Chris Stepanian
>
>>In article <dgerty.81...@draper.com>, dge...@draper.com (David R
>>Gerty) wrote:
>>
>>>
>>> I don't need to remove weight from my bike, I need to remove weight from me.
>>> So why should I pay extra for the light frame, when I can loose more than the
>>> total weight of the bike for free?
>
>Because there is a limit to the amount of weight you can remove from
>yourself. After that minimum value, you need to remove weight elsewhere.
>
to they hype generated for a very small portion of the bike owning population.
A lot of people spend a lot of money to drop a few grams. I remember seeing
a guy at a ride in Pittsburgh who had the most tricked out GREP frame and spokes
that I have ever seen. He also had to weigh about 275lbs.
The important thing, though, is that he was out there.
(at least his wallet lost weight)
cheers,
c.
>
>--
>Chris Pastore |When space doesn't exist, having somebody
>NC State Univ. |unpleasant like Mr. Pber^t Pber^d underfoot all
>919 515 6572 |the time is the most irritating thing.
>chris_...@ncsu.edu | -- Italo Calvino
-------------------------------------------------------
pp00...@interramp.com (Chris Stepanian)
The Lorien Group -- "... feels good to exercise your
rights, doesn't it." - Front Line Assembly/Falling Down
Composite Structure Design/Analysis/Manufacture
-------------------------------------------------------
M Dolenga
(Chris Stepanian) wrote:
> A large (very) portion of the bike owning population seems to fall prey
> to they hype generated for a very small portion of the bike owning population.
> A lot of people spend a lot of money to drop a few grams. I remember seeing
> a guy at a ride in Pittsburgh who had the most tricked out GREP frame and spokes
> that I have ever seen. He also had to weigh about 275lbs.
What is worse - gaining 5 pounds fat, or 5 pounds more on your bike? I
would certainly notice it if my bike became 5 pounds heavier, whereas most
of us wouldn't change all that much if we gained 5 pounds. Any
physics/engineering types out there with a definitive answer (as if there
are any)?
Mike
Jim Papadopoulos
mp...@cornell.edu (M Dolenga) wrote:
> What is worse - gaining 5 pounds fat, or 5 pounds more on your bike? I
> would certainly notice it if my bike became 5 pounds heavier, whereas most
> of us wouldn't change all that much if we gained 5 pounds. Any
> physics/engineering types out there with a definitive answer (as if there
> are any)?
>
That's an excellent question, in my opinion.
I DON'T HAVE A CLUE.
JP
Marco Anglesio
: >In article <dgerty.81...@draper.com>, dge...@draper.com (David R
: >Gerty) wrote:
: >>
: >> I don't need to remove weight from my bike, I need to remove weight from me.
: >> So why should I pay extra for the light frame, when I can loose more than the
: >> total weight of the bike for free?
: Because there is a limit to the amount of weight you can remove from
: yourself. After that minimum value, you need to remove weight elsewhere.
And most people are at that minimum weight?
Of course, if you can lose weight anywhere on the bike, get light rims.
This, however, is a course of action not recommended for the heavier ones
among us (I'm 200lbs, and I doughnut-ed two new Al-alloy rims over the
summer, mountain biking around Vancouver).
marco
--------------------------------------------------------------------------
| Marco Anglesio, Materials and Metallurgical Engineering, Queen's U |
--------------------------------------------------------------------------
| <3m...@jeff-lab.queensu.ca> | Caught between the bright lights/ and |
| <3m...@qlink.queensu.ca> | the far unlit unknown/ nowhere is the |
| <angl...@unixg.ubc.ca> | dreamer/ or the misfit so alone |
--------------------------------------------------------------------------
M.J.Davis
>And most people are at that minimum weight?
Probably not. At ~145lb and 6ft and a bit, I reckon I am :-). Anything
to justify expenditure on components. Having said that, my bike weighs
a porky ~27lb, but it ain't gonna break.
>Of course, if you can lose weight anywhere on the bike, get light rims.
>This, however, is a course of action not recommended for the heavier ones
>among us (I'm 200lbs, and I doughnut-ed two new Al-alloy rims over the
>summer, mountain biking around Vancouver).
Doughnut-ed them? What, you deep-fat-fried them and coated them in
sugar? Interesting approach. Does it improve braking?
:-)
Later,
Mike.
--
Mike Davis _ o
Exeter University, UK ,\<.
cs9...@cen.ex.ac.uk ( )/( )
http://www.dcs.ex.ac.uk/ug/cs92/cs92mjd/mikes_home.html