dear all

I'm going to create a ring with special criteria
some pictures of it can be seen he

http://www.comfx.com/v.php?d=965320
http://www.comfx.com/v.php?d=915997
http://www.comfx.com/v.php?d=917818
http://www.comfx.com/v.php?d=415042

in fact its a half ring with an outer diameter of about 1900 mm, its
shape is some how difficult in some aspects :
- as shown in attached pictures a portion of structure is just an easy
cylinder form but the other portion is conical shaped
- it must be seamless, coldworked and made from stainless steel sheet
- thickness of the sheet is 15 mm
- it must be produced with a good telorance ( the bend shape must b
axact)

my questions are :
which forming process is the best for it?(rolling , spinning , any
other forming process? these are just my guesses )
can it be formed in a full ring and then splited into two halves? or
residual stresses would not let me do something like this even if I
anneal it , and I should form it in a half ring from the begining?

can anybody provide me some information?
any kind of information or sugestion would be precious.
thanks in advance for your care
best regards,
Shantia

The easiest way to do this is in a good sized roll bender with special
dies. Roll a full ring, weld the end together, continue rolling to get
the thing round and the angle fully formed. Cut it apart into 2
completed units.

Most any good structural steel fabrication facility should have the
roller. Dies would be extra.

shantia wrote:
dear all

I'm going to create a ring with special criteria
some pictures of it can be seen he

http://www.comfx.com/v.php?d=965320
http://www.comfx.com/v.php?d=915997
http://www.comfx.com/v.php?d=917818
http://www.comfx.com/v.php?d=415042

in fact its a half ring with an outer diameter of about 1900 mm, its
shape is some how difficult in some aspects :
- as shown in attached pictures a portion of structure is just an easy
cylinder form but the other portion is conical shaped
- it must be seamless, coldworked and made from stainless steel sheet
- thickness of the sheet is 15 mm
- it must be produced with a good telorance ( the bend shape must b
axact)

my questions are :
which forming process is the best for it?(rolling , spinning , any
other forming process? these are just my guesses )
can it be formed in a full ring and then splited into two halves? or
residual stresses would not let me do something like this even if I
anneal it , and I should form it in a half ring from the begining?

can anybody provide me some information?
any kind of information or sugestion would be precious.
thanks in advance for your care
best regards,
Shantia

"shantia" wrote in message
...
dear all

I'm going to create a ring with special criteria
some pictures of it can be seen he

http://www.comfx.com/v.php?d=965320
http://www.comfx.com/v.php?d=915997
http://www.comfx.com/v.php?d=917818
http://www.comfx.com/v.php?d=415042

in fact its a half ring with an outer diameter of about 1900 mm, its
shape is some how difficult in some aspects :
- as shown in attached pictures a portion of structure is just an easy
cylinder form but the other portion is conical shaped
- it must be seamless, coldworked and made from stainless steel sheet
- thickness of the sheet is 15 mm
- it must be produced with a good telorance ( the bend shape must b
axact)

my questions are :
which forming process is the best for it?(rolling , spinning , any
other forming process? these are just my guesses )
can it be formed in a full ring and then splited into two halves? or
residual stresses would not let me do something like this even if I
anneal it , and I should form it in a half ring from the begining?

can anybody provide me some information?
any kind of information or sugestion would be precious.

How much money do you have? You're going to need a bundle.

--
Ed Huntress

"RoyJ" wrote in message
...
The easiest way to do this is in a good sized roll bender...

"Good sized"? Roy, 15mm material thickness is over 0.59". The cone is
attached to the straight cylinder, so one edge is going to have to be
stretched or the other is going to have to be shrunk -- or a little bit of
both -- while you keep that blend radius intact.. And this is stainless! You
can't just roll it. you have to iron it at the same time, and ironing it out
so it doesn't twist is going to be an extreme metalworking job.

Unless you have access to the machines used for making Saturn V rocket
nozzles, I think there is a problem here. d8-) The forces involved are
astronomical.

--
Ed Huntress

"Ed Huntress" wrote in message
...

"RoyJ" wrote in message
...
The easiest way to do this is in a good sized roll bender...

"Good sized"? Roy, 15mm material thickness is over 0.59". The cone is
attached to the straight cylinder, so one edge is going to have to be
stretched or the other is going to have to be shrunk -- or a little bit of
both -- while you keep that blend radius intact.. And this is stainless!
You can't just roll it. you have to iron it at the same time, and ironing
it out so it doesn't twist is going to be an extreme metalworking job.

Unless you have access to the machines used for making Saturn V rocket
nozzles, I think there is a problem here. d8-) The forces involved are
astronomical.

--
Ed Huntress


That 15mm must a typo. If the ring is truly that thick, a blank ring could
be rolled and welded, then turned on a lathe.

"Chas Hurst" wrote in message
. ..

"Ed Huntress" wrote in message
...

"RoyJ" wrote in message
...
The easiest way to do this is in a good sized roll bender...

"Good sized"? Roy, 15mm material thickness is over 0.59". The cone is
attached to the straight cylinder, so one edge is going to have to be
stretched or the other is going to have to be shrunk -- or a little bit
of both -- while you keep that blend radius intact.. And this is
stainless! You can't just roll it. you have to iron it at the same time,
and ironing it out so it doesn't twist is going to be an extreme
metalworking job.

Unless you have access to the machines used for making Saturn V rocket
nozzles, I think there is a problem here. d8-) The forces involved are
astronomical.

--
Ed Huntress


That 15mm must a typo. If the ring is truly that thick, a blank ring could
be rolled and welded, then turned on a lathe.

With a 1900 mm diameter? Even for a VTL, that's a big piece of work, and it
isn't going to be cheap to get it done. The material cost alone --
especially if you roll the cone section, which would have to be cut out of a
pretty large plate of 15 mm stock (assuming it's not a typo) -- would be a
hefty chunk of change -- over $3,000 for that one piece of plate. The stock
for the cylindrical ring will be on the same order. Then there's rolling,
and welding, and turning. That assumes it was done by someone who is really
expert and that it doesn't wind up being all distorted out of shape. With
1/2" - plus stainless, that's more than a little problematic, matching a
cone to a cylinder.

As I said, it's all a matter of how much money one has. The total job is
going to run into five figures. This is extreme stuff. I think the first
point here is to see if the OP is aware of what the cost is likely to be.

--
Ed Huntress

"Ed Huntress" wrote in message
...

"Chas Hurst" wrote in message
. ..

"Ed Huntress" wrote in message
...

"RoyJ" wrote in message
...
The easiest way to do this is in a good sized roll bender...

"Good sized"? Roy, 15mm material thickness is over 0.59". The cone is
attached to the straight cylinder, so one edge is going to have to be
stretched or the other is going to have to be shrunk -- or a little bit
of both -- while you keep that blend radius intact.. And this is
stainless! You can't just roll it. you have to iron it at the same time,
and ironing it out so it doesn't twist is going to be an extreme
metalworking job.

Unless you have access to the machines used for making Saturn V rocket
nozzles, I think there is a problem here. d8-) The forces involved are
astronomical.

--
Ed Huntress


That 15mm must a typo. If the ring is truly that thick, a blank ring
could be rolled and welded, then turned on a lathe.

With a 1900 mm diameter? Even for a VTL, that's a big piece of work, and
it isn't going to be cheap to get it done. The material cost alone --
especially if you roll the cone section, which would have to be cut out of
a pretty large plate of 15 mm stock (assuming it's not a typo) -- would be
a hefty chunk of change -- over $3,000 for that one piece of plate. The
stock for the cylindrical ring will be on the same order. Then there's
rolling, and welding, and turning. That assumes it was done by someone who
is really expert and that it doesn't wind up being all distorted out of
shape. With 1/2" - plus stainless, that's more than a little problematic,
matching a cone to a cylinder.

As I said, it's all a matter of how much money one has. The total job is
going to run into five figures. This is extreme stuff. I think the first
point here is to see if the OP is aware of what the cost is likely to be.

--
Ed Huntress

I'd didn't say it would be cheap.
There are companies that specialize in rings and one this size is would be
no problem at all. I think the whole ring could be made from one piece and
turned on a vertical lathe, eliminating welding.

These guys are somewhat local to me. IIRC, they have a suitable roller.
http://www.bendtec.com/architec.html

I'm inclined to believe the OP is real on the thickness, the drawings
show a pretty hefty thickness in relation to the width. The blank would
be a 20' piece of 5/8"x 8"(?) 304. Calculated weight would be 336
pounds. I haven't priced stainless lately, not calibrated on that one.
I'd certainly hope to get it for less that $5 a pound, that would put
the piece under $2000.

My biggest concern is the OP may think that a fabricated piece will hold
the same tolerances as a machined piece. BTDT, had a very unhappy customer.


Ed Huntress wrote:
"RoyJ" wrote in message
...
The easiest way to do this is in a good sized roll bender...

"Good sized"? Roy, 15mm material thickness is over 0.59". The cone is
attached to the straight cylinder, so one edge is going to have to be
stretched or the other is going to have to be shrunk -- or a little bit of
both -- while you keep that blend radius intact.. And this is stainless! You
can't just roll it. you have to iron it at the same time, and ironing it out
so it doesn't twist is going to be an extreme metalworking job.

Unless you have access to the machines used for making Saturn V rocket
nozzles, I think there is a problem here. d8-) The forces involved are
astronomical.

--
Ed Huntress

"RoyJ" wrote in message
...
These guys are somewhat local to me. IIRC, they have a suitable roller.
http://www.bendtec.com/architec.html

I'm inclined to believe the OP is real on the thickness, the drawings show
a pretty hefty thickness in relation to the width. The blank would be a
20' piece of 5/8"x 8"(?) 304. Calculated weight would be 336 pounds. I
haven't priced stainless lately, not calibrated on that one. I'd certainly
hope to get it for less that $5 a pound, that would put the piece under
$2000.

My biggest concern is the OP may think that a fabricated piece will hold
the same tolerances as a machined piece. BTDT, had a very unhappy
customer.

I agree a fabrication would present problems.
It's possible a casting could be made. A quick search just dug up a few
companies that have the capability.

Ed Huntress wrote:
"RoyJ" wrote in message
...
The easiest way to do this is in a good sized roll bender...

"Good sized"? Roy, 15mm material thickness is over 0.59". The cone is
attached to the straight cylinder, so one edge is going to have to be
stretched or the other is going to have to be shrunk -- or a little bit
of both -- while you keep that blend radius intact.. And this is
stainless! You can't just roll it. you have to iron it at the same time,
and ironing it out so it doesn't twist is going to be an extreme
metalworking job.

Unless you have access to the machines used for making Saturn V rocket
nozzles, I think there is a problem here. d8-) The forces involved are
astronomical.

--
Ed Huntress

"RoyJ" wrote in message
...
These guys are somewhat local to me. IIRC, they have a suitable roller.
http://www.bendtec.com/architec.html

I'm inclined to believe the OP is real on the thickness, the drawings show
a pretty hefty thickness in relation to the width. The blank would be a
20' piece of 5/8"x 8"(?) 304. Calculated weight would be 336 pounds. I
haven't priced stainless lately, not calibrated on that one. I'd certainly
hope to get it for less that $5 a pound, that would put the piece under
$2000.

My biggest concern is the OP may think that a fabricated piece will hold
the same tolerances as a machined piece. BTDT, had a very unhappy
customer.

I can't see how you'd do the angle (cone) and the cylinder (flat) on a pipe
bender, Roy, but I'll be interested to hear if they'll give a quote, and
what it is.

--
Ed Huntress

On Jan 5, 5:12*pm, "Ed Huntress" wrote:


As I said, it's all a matter of how much money one has. The total job is
going to run into five figures. This is extreme stuff. I think the first
point here is to see if the OP is aware of what the cost is likely to be.

--
Ed Huntress

It's especially inspiring that the OP doesn't seem to know how to make
such a part, nor does he have any actual tolerance.

A part like this would be *very* difficult to measure without the use
of a CMM. Application-based gauging would be important, especially
when the customer says "no" and the builder says "yes". A good
description of the part's function would be nearly a requirement to
avoid shenanigans.

Regards,

Robin

Operative word is 'roller'

A quick google brought up this mfg: The largest unit on this page
http://www.wikco.com/rbndr.html
will easily handle this cross section. Most of these roll benders will
operate in either the vertical position (shown) or horizontal position
(better for this project) There is a max size calculator at the bottom
of the page.

You would need to make one male roller and two female rollers. These
would be some pretty massive chunks of tool steel, probably 8" in
diameter by 9" long (1/2" flanges to contain the 8" material on each
side). The rollers are easy to make: turn on a lathe, bore the center
hole, broach the keyway, heat treat.

The OP's shape would require that one side would need to shrink, hard to
do in a roller. In real life, multiple passes through the roller will
likely stretch the outside some. That makes the final diameter a bit of
a guess.

Final process would probably be: roll with flat roller (or in a big slip
roll), weld the ends together, start forming the angle leg of the
ring. I'd expect that you would need to cut out a section and reweld to
get the diameter just right. This is not an easy part to make but I'd
hope to get one finished ring out per 8 hour shift with a team of two.

BTW: the equipment in the shop that I interned in (just down the block
from BendTec) had an 8'x1" shear and an 8' slip roll that was quite
happy with 8' x26' of 3/8" plate, used to make tanks and industrial
furnace duct work. Lots of similar places around the country.

Ed Huntress wrote:
"RoyJ" wrote in message
...
These guys are somewhat local to me. IIRC, they have a suitable roller.
http://www.bendtec.com/architec.html

I'm inclined to believe the OP is real on the thickness, the drawings show
a pretty hefty thickness in relation to the width. The blank would be a
20' piece of 5/8"x 8"(?) 304. Calculated weight would be 336 pounds. I
haven't priced stainless lately, not calibrated on that one. I'd certainly
hope to get it for less that $5 a pound, that would put the piece under
$2000.

My biggest concern is the OP may think that a fabricated piece will hold
the same tolerances as a machined piece. BTDT, had a very unhappy
customer.

I can't see how you'd do the angle (cone) and the cylinder (flat) on a pipe
bender, Roy, but I'll be interested to hear if they'll give a quote, and
what it is.

--
Ed Huntress

"RoyJ" wrote in message
...
Operative word is 'roller'

A quick google brought up this mfg: The largest unit on this page
http://www.wikco.com/rbndr.html
will easily handle this cross section. Most of these roll benders will
operate in either the vertical position (shown) or horizontal position
(better for this project) There is a max size calculator at the bottom of
the page.

snip

OK, but I don't see it, Roy. The angled flange, or cone section if you
prefer, is going to wrinkle like crazy if you try to do this on a roll
former. Custom roller profiles won't help, IMO. Rolling a perpendicular
angle is a lot easier, because the leg is not trying to spring to the
outside -- they just constrain it like the walls on a piece of rectangular
tube.

There just is no way I can see to apply the force necessary to compress an
angled flange progressively, so that it doesn't wrinkle, with a normal roll
former. The forces required would be huge.

But maybe the OP will want to call a roller manufacturer or a jobber and see
what they say.

--
Ed Huntress

If you read up on the roller mfg, they do ANGLE IRON rolls with the leg
***IN***. Sure, they have limitations on how long the leg is but it can
and is done every day. For the angle iron, the roller die has to have a
suitable slot so the inward leg is constrained while bending. It is
being compressed so it will expand (the web will get thicker).

For the OP's profile, the main web needs to expand, leaving the inward
flange at close to the original diameter.

Ed Huntress wrote:
"RoyJ" wrote in message
...
Operative word is 'roller'

A quick google brought up this mfg: The largest unit on this page
http://www.wikco.com/rbndr.html
will easily handle this cross section. Most of these roll benders will
operate in either the vertical position (shown) or horizontal position
(better for this project) There is a max size calculator at the bottom of
the page.

snip

OK, but I don't see it, Roy. The angled flange, or cone section if you
prefer, is going to wrinkle like crazy if you try to do this on a roll
former. Custom roller profiles won't help, IMO. Rolling a perpendicular
angle is a lot easier, because the leg is not trying to spring to the
outside -- they just constrain it like the walls on a piece of rectangular
tube.

There just is no way I can see to apply the force necessary to compress an
angled flange progressively, so that it doesn't wrinkle, with a normal roll
former. The forces required would be huge.

But maybe the OP will want to call a roller manufacturer or a jobber and see
what they say.

--
Ed Huntress

"RoyJ" wrote in message
...
If you read up on the roller mfg, they do ANGLE IRON rolls with the leg
***IN***. Sure, they have limitations on how long the leg is but it can
and is done every day. For the angle iron, the roller die has to have a
suitable slot so the inward leg is constrained while bending. It is being
compressed so it will expand (the web will get thicker).

Yeah, I read it, and I visited a number of roll-forming operations when I
was writing for fabricating magazines. Again, the thing to do here is to
talk to a jobber or equipment manufacturer. I don't think the dynamics will
work out, Roy.

Without making a long story out of it, the forces involved in bending angle
iron or channel apply the stretching (outside leg) or shrinking (inside leg)
to the web (the leg) in such a way that there is no lateral load on the web.
Yes, it needs constraint, because it will seek relief by moving in or out,
but there is no *resisting force* encouraging it one way or the other. If
you can keep it from starting to wrinkle with a lateral guide roller, you
can overcome that tendency of the web to move sideways to seek relief, and
you'll get it to shrink, if you apply enough force.

With the angled web (the flange, or the cone shape) the resisting force is
trying to flatten the web back into its original plane all the time. It's
always pushing against the outside restraining roller, assuming you're using
an outside restraining roller. And the force trying to press that web flat
is considerable. In this case there is not only a tendency for the web to
resist compression (shrinking) but there also is a force trying to *relieve*
it: the resisting force that's trying to flatten the web back to its
original plane.

This is going to produce a lot of wrinkling. I'd bet on it. But I would talk
to an equipment manufacturer before betting money on anything here one way
or the other.


For the OP's profile, the main web needs to expand, leaving the inward
flange at close to the original diameter.

Ed Huntress wrote:
"RoyJ" wrote in message
...
Operative word is 'roller'

A quick google brought up this mfg: The largest unit on this page
http://www.wikco.com/rbndr.html
will easily handle this cross section. Most of these roll benders will
operate in either the vertical position (shown) or horizontal position
(better for this project) There is a max size calculator at the bottom
of the page.

snip

OK, but I don't see it, Roy. The angled flange, or cone section if you
prefer, is going to wrinkle like crazy if you try to do this on a roll
former. Custom roller profiles won't help, IMO. Rolling a perpendicular
angle is a lot easier, because the leg is not trying to spring to the
outside -- they just constrain it like the walls on a piece of
rectangular tube.

There just is no way I can see to apply the force necessary to compress
an angled flange progressively, so that it doesn't wrinkle, with a normal
roll former. The forces required would be huge.

But maybe the OP will want to call a roller manufacturer or a jobber and
see what they say.

--
Ed Huntress

well I think Ed is right , the conical part will wrinkle without any
doubt if I just use a simple roll forming.

but no one had seen how such part is created? I myself think of spin
forming , maybe shear spin forming or flow forming

the fact is we don't concern about the money , even about 16000 $ is
just fine , but we don't know investing in which way would be better.

as I mentioned before , casting is not allowed , it should be formed
from sheet.

once someone mentioned of machines used for making Saturn V rocket
nozzles , anybody know what machines do they use for that forming
process , I'm sure theire material is much more stronger than
stainless steel.

On further reflection, I'd run the two outside rollers as flat
cylinders, run the center (movable one) with the correct profile. Make
multiple passes. That will force the flat section to stretch, leaves the
flanged area untouched until the end.

Ed Huntress wrote:
"RoyJ" wrote in message
...
If you read up on the roller mfg, they do ANGLE IRON rolls with the leg
***IN***. Sure, they have limitations on how long the leg is but it can
and is done every day. For the angle iron, the roller die has to have a
suitable slot so the inward leg is constrained while bending. It is being
compressed so it will expand (the web will get thicker).

Yeah, I read it, and I visited a number of roll-forming operations when I
was writing for fabricating magazines. Again, the thing to do here is to
talk to a jobber or equipment manufacturer. I don't think the dynamics will
work out, Roy.

Without making a long story out of it, the forces involved in bending angle
iron or channel apply the stretching (outside leg) or shrinking (inside leg)
to the web (the leg) in such a way that there is no lateral load on the web.
Yes, it needs constraint, because it will seek relief by moving in or out,
but there is no *resisting force* encouraging it one way or the other. If
you can keep it from starting to wrinkle with a lateral guide roller, you
can overcome that tendency of the web to move sideways to seek relief, and
you'll get it to shrink, if you apply enough force.

With the angled web (the flange, or the cone shape) the resisting force is
trying to flatten the web back into its original plane all the time. It's
always pushing against the outside restraining roller, assuming you're using
an outside restraining roller. And the force trying to press that web flat
is considerable. In this case there is not only a tendency for the web to
resist compression (shrinking) but there also is a force trying to *relieve*
it: the resisting force that's trying to flatten the web back to its
original plane.

This is going to produce a lot of wrinkling. I'd bet on it. But I would talk
to an equipment manufacturer before betting money on anything here one way
or the other.

For the OP's profile, the main web needs to expand, leaving the inward
flange at close to the original diameter.

Ed Huntress wrote:
"RoyJ" wrote in message
...
Operative word is 'roller'

A quick google brought up this mfg: The largest unit on this page
http://www.wikco.com/rbndr.html
will easily handle this cross section. Most of these roll benders will
operate in either the vertical position (shown) or horizontal position
(better for this project) There is a max size calculator at the bottom
of the page.
snip

OK, but I don't see it, Roy. The angled flange, or cone section if you
prefer, is going to wrinkle like crazy if you try to do this on a roll
former. Custom roller profiles won't help, IMO. Rolling a perpendicular
angle is a lot easier, because the leg is not trying to spring to the
outside -- they just constrain it like the walls on a piece of
rectangular tube.

There just is no way I can see to apply the force necessary to compress
an angled flange progressively, so that it doesn't wrinkle, with a normal
roll former. The forces required would be huge.

But maybe the OP will want to call a roller manufacturer or a jobber and
see what they say.

--
Ed Huntress

"shantia" wrote in message
...
well I think Ed is right , the conical part will wrinkle without any
doubt if I just use a simple roll forming.

but no one had seen how such part is created? I myself think of spin
forming , maybe shear spin forming or flow forming

the fact is we don't concern about the money , even about 16000 $ is
just fine , but we don't know investing in which way would be better.

as I mentioned before , casting is not allowed , it should be formed
from sheet.

once someone mentioned of machines used for making Saturn V rocket
nozzles , anybody know what machines do they use for that forming
process , I'm sure theire material is much more stronger than
stainless steel.

I was joking about the Saturn V. The engine (Rocketdyne F-1) has several
sections of curved shapes and most of them are double-walled, so I don't now
how relevant it would be.

Have you called any fabricators who specialize in thick metal, to see what
they say?

--
Ed Huntress

in fact we have called some , but no one accept the risk of it.

they just suggest to thinking on roll forming , spin forming ,
stretching or a mixed up of them!

On Sun, 6 Jan 2008 11:09:27 -0800 (PST), shantia
wrote:

in fact we have called some , but no one accept the risk of it.

they just suggest to thinking on roll forming , spin forming ,
stretching or a mixed up of them!

I spent a couple years off and on designing equipment and tooling for
GE's medium steam turbine division while they were in the process of
consolidating several plants. I saw plenty of parts not so different
from what you've got. They were generally fabricated, welded, stress
relieved, and machined. Most internal parts were 400 series stainless
steel. I'm sure the more complicated parts bounced back and forth
between those processes several times.

Which is my long winded way of getting around to the suggestion that
you check with companies that rebuild and repair turbines, for
example:
http://www.turbocare.com/page1498.html

--
Ned Simmons

"shantia" wrote in message
...
in fact we have called some , but no one accept the risk of it.

they just suggest to thinking on roll forming , spin forming ,
stretching or a mixed up of them!

Too bad. Roll forming is a very tricky thing when you depart from a few
standard shapes, as we've discussed. Ram-forming or some kind of
mandrel-stretching probably would be the way to go if you were making a lot
of them, but I can see the tooling costing $100,000 or more because of all
the constraints that would be required to prevent twisting and wrinkling.

Conceptually, it could be spun, but it would require an enormous specialized
lathe (probably a custom-built VTL) and I've never heard of such a thing,
except, in photos only, some machines built for the rocket-engine business.
Even there, I have no idea if they could handle making a bell-type expansion
in 15 mm stainless. The superalloys used in some rocket parts really aren't
that much different in terms of properties, at room temperatures, than some
grades of stainless. They're generally high-nickel, high-temperature
"superalloys." And I don't know where those machines would be today. Pratt &
Whitney Aircraft probably would know.

Can you tell us what the application is, or is it a secret?

--
Ed Huntress

well Mr Simmons' recognition is nice, in fact its one of parts of an
industrial turbine.(somehow its a secret , so keep it just secret
here ;-) )

Mr Simmons , can you please help me just a bit more , I just want to
know how GE make such parts , even if you yourself don't know much ,
maybe you can introduce someone else to me who has experience in this
area.

And I could see about $3000 in tooling with a piece part price of $1500
for labor as long as the process would produce parts to the OP's
requirements.

It is totally unclear whether there are strict tolerances on this item
or if it might be a one off archway for an office building.

Ed Huntress wrote:
"shantia" wrote in message
...
in fact we have called some , but no one accept the risk of it.

they just suggest to thinking on roll forming , spin forming ,
stretching or a mixed up of them!

Too bad. Roll forming is a very tricky thing when you depart from a few
standard shapes, as we've discussed. Ram-forming or some kind of
mandrel-stretching probably would be the way to go if you were making a lot
of them, but I can see the tooling costing $100,000 or more because of all
the constraints that would be required to prevent twisting and wrinkling.

Conceptually, it could be spun, but it would require an enormous specialized
lathe (probably a custom-built VTL) and I've never heard of such a thing,
except, in photos only, some machines built for the rocket-engine business.
Even there, I have no idea if they could handle making a bell-type expansion
in 15 mm stainless. The superalloys used in some rocket parts really aren't
that much different in terms of properties, at room temperatures, than some
grades of stainless. They're generally high-nickel, high-temperature
"superalloys." And I don't know where those machines would be today. Pratt &
Whitney Aircraft probably would know.

Can you tell us what the application is, or is it a secret?

--
Ed Huntress

what is unclear?!
as I said , its a turbine part , so tolerances are strict , if you
need it , the deviation in diameter is not more than 0.15 mm in 1860
mm , in inch :0.006 inch in 73 inch
is it clear now?

"shantia" wrote in message
...
what is unclear?!
as I said , its a turbine part , so tolerances are strict , if you
need it , the deviation in diameter is not more than 0.15 mm in 1860
mm , in inch :0.006 inch in 73 inch
is it clear now?

Holy cow. Forget rolling, then. In fact, forget any kind of forming, unless
it's followed by machining. And as for machining, you're pushing beyond the
limits for machining a weldment that's going to move around as the weld is
machined off and it relieves the stresses. Because a stainless steel
weldment of that size is going to be loaded with stresses, unless it's
thoroughly annealed first.

In other words, this is a multi-step job no matter how you look at it. I
think you're looking at roll-forming two pieces (the flange, if it's
attached to the cylindrical section at 45 deg., as it appears to be, will
have to be a quarter-circle cut out of a large plate, which is why I pegged
the material price for that piece at over $3,000); welding them; annealing
the whole works to relieve all stresses; and then turning it to final shape.
And after you unclamp it from the VTL faceplate, I'll bet it will still move
more than 0.15 mm in 1860 mm. It will have to be re-clamped and
finish-machined in a separate operation. All of which means that if you
truly need 15 mm thickness you're going to have to start with something
thicker than that.

If these are the specs you've given to possible vendors, I'm not surprised
they won't bid on it. The final tolerance is a killer. It would be easier if
you left it as a complete ring, because the springing from stress relief
would be better constrained.

--
Ed Huntress

On Sun, 6 Jan 2008 13:59:42 -0800 (PST), shantia
wrote:

well Mr Simmons' recognition is nice, in fact its one of parts of an
industrial turbine.(somehow its a secret , so keep it just secret
here ;-) )

Mr Simmons , can you please help me just a bit more , I just want to
know how GE make such parts , even if you yourself don't know much ,
maybe you can introduce someone else to me who has experience in this
area.

My contact there has long since retired, so the best I can do is
speculate based on what I saw while working on various projects and
extrapolating to your part. The processes are not unusual or unique -
I presume the value here is the confirmation that I saw parts similar
to yours fabricated in this manner.

-Roll the cylindrical segment from a rectangular piece of plate
-Roll the conical segment from a semicircular piece of plate
-Weld the segments together
-Stress relieve
-Finish machine

The black art in this sequence is the practical, hands-on knowledge
required to control welding distortion, and to predict how much the
rough weldment must be oversized to allow machining to size to
accommodate the distortion that can't be controlled.

--
Ned Simmons

"shantia" wrote in message
...
what is unclear?!
as I said , its a turbine part , so tolerances are strict , if you
need it , the deviation in diameter is not more than 0.15 mm in 1860
mm , in inch :0.006 inch in 73 inch
is it clear now?

I re-thought this because something has been nagging at me. Because you said
"sheet" I've been thinking in terms of plate. This isn't a plate-rolling
job. It's a ring-forging job.

It could be ring-forged and then machined. You'd have to start with a
complete ring but you'd have a fairly low-stress part after machining. Then
you might be able to achieve your tolerances.

Search on "ring forging." I think you'll find what you're looking for. You
might even make your projected cost.

Sorry I floundered around on this. I usually can identify the process needed
for doing odd jobs, after decades of reporting on practically the whole
metalworking field, but sometimes we trap ourselves into one line of
thinking when we should be looking at another. Once I thought of it as a
complete ring, it jarred my thinking.

This job is right up the alley for ring-forging.

--
Ed Huntress

On Mon, 7 Jan 2008 11:24:27 -0500, "Ed Huntress"
wrote:


Search on "ring forging." I think you'll find what you're looking for. You
might even make your projected cost.

I like it.
http://www.scotforge.com/equipment/s...p_ringmill.htm
http://www.scotforge.com/sf_facts_rollring.htm
http://www.scotforge.com/videos/sf_rings320_240.mpg

--
Ned Simmons

I think a part like this would cost a LOT more than $1500 per part.

The way it would probably be done in industry these days is to get
somebody like Scot Forge
http://www.scotforge.com/
to roll forge you a blank.
This would give you an oversize ring, without welds, that had the
grain forged continuosly around the circumference for strength.

Then, you send it to a machine shop that has a good sized VTL or VBM.

I was in a factory in Italy a couple of years ago that built big
machines, and they were making similar sized and shaped parts in this
way- a roll forged ring, machined on a vertical lathe about the size
of a two car garage. They had a whole row of these machines at work.

The material cost is one thing- but the real cost is in the equipment
capable of doing this size of work to these tolerances, and the
experience and infrastructure to support these machines.

This aint no garage job.

Like I said- If I seriously needed one of these, I would pick the
brains of companies that do it everyday, as job shops, and I would
start with Scot.

"Ries" wrote in message
...

I think a part like this would cost a LOT more than $1500 per part.

Shantia said "$16,000 is just fine," so it should be OK, if he's making more
than one. He did mention that making a full ring and splitting it would be
OK, too. However, he said at one early point that it had to be cold-formed,
while this process is hot-forming. But he may have been thinking only about
casting as the alternative.


The way it would probably be done in industry these days is to get
somebody like Scot Forge
http://www.scotforge.com/
to roll forge you a blank.

I agree -- especially if he's going to make more than a couple of them. The
first one will cost a bundle.

This would give you an oversize ring, without welds, that had the
grain forged continuosly around the circumference for strength.

Then, you send it to a machine shop that has a good sized VTL or VBM.

I was in a factory in Italy a couple of years ago that built big
machines, and they were making similar sized and shaped parts in this
way- a roll forged ring, machined on a vertical lathe about the size
of a two car garage. They had a whole row of these machines at work.

The material cost is one thing- but the real cost is in the equipment
capable of doing this size of work to these tolerances, and the
experience and infrastructure to support these machines.

This aint no garage job.

Like I said- If I seriously needed one of these, I would pick the
brains of companies that do it everyday, as job shops, and I would
start with Scot.

shantia wrote:

the deviation in diameter is not more than 0.15 mm in 1860
mm , in inch :0.006 inch in 73 inch is it clear now?

Hahaha! And you want to roll-form that or spin it!? Forget it. Simply forget
it. As soon as you cut it, it will spring in *any* direction.
You just can start with a forged part or a ticker rolled part, stress-relief
it. Pre-machine it, stress-relief it again and then finish it.


Nick
--
The lowcost-DRO:
http://www.yadro.de