Hydraulic Pipe Bending Machine

There are simple shareware programs that will give you a reference that I tend to use.

BeamBoy is one, just establish you pipe size, Material Properties, supports, force and force location, and look at the bend or deflect results. This will give you a good reference and force required.

You also have to realize the quality of your product, such as are you going to use an internal mandrel to limit deformation.

There are other actual forces may be difficult to calculate, such as pushing the mandrel through. but not impossible.

You can look up the yield stress for the pipe material, use that value for σ, and then calculate W.

Then maybe multiply by say 1.25 as a service factor.

The equation is valid ONLY for elastic deformations. When you bend a pipe most of the section is loaded in the plastic domain and a small section in the elasto-plastic domain. For both the equation is NOT valid. I have also the feeling that suggested soft is limited to the ealstic domain.

However it is possible to define a relationship based on the material properties, on the tube dimensions and the ratio between the mean tube diameter and the mean radius after bending. The results depend on several factors as material behavior in the transelastic domain, the temperature (value is not same at -20°C and +30°C for instance), the tube guide profile (because of lateral friction since the tube becomes oval and presses on the guide) and so on.

I know this because years ago I worked with a company which had as product also pipe benders and participated at different discutions when results were not corresponding to expectations.

Even if you make good calculations you will be obliged to make several tests and correct the theory according to empirical results.

For the start you could consider that after the yield point the stress in the tube stays constant. It is not true but the equivalent of the Young modulus in the plastic range is small and it will be a good approximation.

We have many types and makes of hydraulic pipe benders on the market. From simple manual sets to CNC automatic production devices.

Is your pipe that special, so existing machines cannot handle the job?

If yes, better specify the pipe: diameter(s), material, wall thickness and more specifics, so that our guess has some window to think in. Or are you a machine builder?

I thought it may be school work, considering we just has something similar.

Hydraulic Tubing Bender and Fittings

HI to all ... thanx for all ur valuable suggestions .. i'l go through all my errors.... hope i could arrive to correct conclusions ...