I am wanting to design a tube bender capable of bending 2"X4" rectangular tubing.Do anyone knows how to calculate how much force that would be required to bend tubing this size?I was thinking maybe building a cnc mandrel tube bender using a 40 hp electric motor.Input would be greatly appreciated.

Material and wall? Easy way or hard way? Bend radius?

Material and wall? Easy way or hard way? Bend radius?

Mikek10,

Thank you for responding. The material is 2"X4" mild steel and the minimum wall thickness is .25". I will be bending the easy way and the bend radius will be 10 inches up to 13 inches.

The figures I am getting are:

Bend Force = 0.8 Newton Metres
Pressure Die Force = 285.7 Nm
Mandrel Force = 114.3 Nm
Clamp Force = 114.3 Nm
Wiper Die Force 85.7 Nm

I would work on a safety factor of at least 3, probably more on the bend force which looks surprisingly low to be honest

I must have been having an off day when I worked out the figures above - did them in mm rather than inches!

Real figures are:

Bend Force = 9365 Newton Metres
Pressure Die Force = 184335 Nm
Mandrel Force = 36867 Nm
Clamp Force = 36867 Nm
Wiper Die Force 55301 Nm

Mike,
What equations are you using for those calculations? I am interested in being able to calculate various round tubing (steel) sizes and wall thicknesses. Any help would be greatly appreciated!

brodybaker@gmail.com

I work for a company that manufactures tube bending machines.

We have written a program to do these calculations for inhouse use and for doing xyz>ybc conversion etc. Though we have sold copies on occasion

You can't apply force with the wiper die. The mandrel force = clamp force doesn't make any sense either.

Its the force against the wiper

mandrel force always equals clamp force