How can fabricate offset cone from a steel plate?
You have to determine what the flattened shape of the unrolled cone will be, then have it rolled into shape. By “offset” cone I presume you mean the large and small diameter holes are non-concentric. This is hard to calculate a flat shape for, much less fabricate. Try contacting suppliers of large-diameter steel pipe and tubing; many of them can roll such shapes or know somebody who can. It will be a lot easier and cheaper if you can make the cone straight. If you aren’t concerned with it being pretty, instead of rolling, it can also be step-formed on a press break. Either way the flat pattern will need some extra material at each end, usually about 4 inches (100mm), for the bottom rollers or die. And the seam will need to be beveled and welded up, then (if you’re worried about smoothness) ground smooth. An option you may consider… Buy an eccentric pipe reducer from somebody like Ladish and chop it up, and/or fabricate adapters for it. My Ladish catalog has eccentric reducers from 24
