[COLOR=black][/COLOR]Greetings to all,I am trying to know whether there is a simple method or command to get development of a transition piece (one side of which is a square or a rectangle and other side is round). If anyone have any suggestion about this topic please revert back.

A simple method using AutoCAD?  No, not without an add-on program or a custom lisp routine.  You would have better luck using Inventor.

See : uploads/175428/RIZZA_01.dwg
 
Hello cadolcolic and John, I use 3D to modelize the frame at the neutral fiber and the command EDGESURF between 2 arcs ( 1 verry little and 1 of the big radius ).
Then I explode the result and use ALIGN with 3 + 3 points to put it flat.
The result gives also the dimensions of the sheets to buy.
AutoCAD won't do smooth surfaces between 2 arcs and the result is with facets but it's OK as this is going to be the real way to fabricate it by bending and not rolling.
I also use this method for non cylindrical cones.
I have a lisp file to open a cylindrical tube with a slash cut that will give me a final result.
 

Like I said, it is not a simple method.  There is no "magic" button.  Interesting approach none-the-less.
John Connor2015-04-17 13:31:08