Smart questions
Smart answers
Smart people
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Member Login




Remember Me
Forgot Password?
Join Us!

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips now!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

Join Eng-Tips
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.
Jobs from Indeed

Link To This Forum!

Partner Button
Add Stickiness To Your Site By Linking To This Professionally Managed Technical Forum.
Just copy and paste the
code below into your site.

windseaker1 (Mechanical) (OP)
29 Jan 09 18:25
I ran across this formula, but it is only good up to 180Degrees?
(.01743xrad)x degree of circle

And I beleive this is not true as well: given
Roll-out flat pattern:
OD = 6.375      material .375 steel   
     Cir.  6.375 x 3.1415  =  20.027
                                 
Formula: (.01745xR) (180 Degrees)x2 =
         (.01745x3.1875) x (180)x2  =
         (.055621875) x 180      x2 =
          10.11937 x2               =
                     20.023875, which is the same as cir.??


A better formula appears to be: but for alum. only??
   (I dont know where the .0078 factor cam from)

(.01745xR)-(.0078xT)x(180 Degrees)x2=
(.055621875)-(.002925)x180x2  =
(.052696875)x180x2            =
9.4854375x2                   =
18.970875

 But evern better "I hope" is AutoCad's factor formula:
     (for mild steel: A36)
By AutoCAD: using .407 factor Times thickness
             = .0763 of the 3/8
       Then offset from the insideat this factor,
           you get: Length was a total of 19.329"

This seems closer to a real stretch-out pattern!

Can anyone confirm??









 
cloa (Petroleum)
29 Jan 09 19:39
Good for you to supply some specific numbers but what is your situation that you want help with?
Helpful Member!(2)  berkshire (Aeronautics)
30 Jan 09 4:44
the second formula you gave will work with steel if you modify the the (.0078xt)in your formula,This is the neutral line, the point where the metal neither stretches nor shrinks.
For a large radius this point, sometimes called the K factor is closer to the middle of the metal thickness. not the inside edge.
Here is a link to a bend program that can be downloaded
http://www.ciri.org.nz/bendworks/bending.pdf

B.E.
windseaker1 (Mechanical) (OP)
30 Jan 09 11:10
I understand the bending formula quite well, except rolling. Are you say that the bend formula is the same for rolling as well??
This the neutral axis of bending the same as rolling??
TheTick (Mechanical)
30 Jan 09 11:13
(.01743xrad)x degree of circle = ???

It's not a formula until there's something on both sides of the equal sign.
Helpful Member!  SnTMan (Mechanical)
30 Jan 09 12:33
windseaker1, what is mostly used for rolling a cylinder from flat plate is the finished mean diameter, pi*(OD-t), or pi*(ID+t). Some add allowance for weld seam shrinkage (1/8" typical), some don't.

Regards

Mike
berkshire (Aeronautics)
31 Jan 09 3:42
windseaker1
Sorry for being late getting back, yes the bend formula works for rolling as well, when you roll a plate you are bending it on a large radius, the metal still has to shrink on the inside of the neutral line and stretch on the outside.To get a finished diameter that you want, you have to compensate by adding or subtracting part of the metal thickness  from the neutral line.
B.E.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close