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