as compared to crush/crimp bending process? can someone explain to me how they do that?

 

They bend the pipe, then pull a ball thru it. That's the simple answer, perhaps someone here has a more technical one?

 

they put ball in the pipe while they bend it.

The ***** are the same size as the inner diameter of the pipe, and they are connected to each other by a shank. The shank is flexible, so it can snake around. When they put this in at the point that they are going to bend, and then they bend it. They also use special tools around the bend die to prevent deforming of the pipe.. But that's the jist of it.

Now days, they are moving more to hydroforming, or pressure bending. When a normal bend occurs, it decreases the volume inside the piping. So what they are now doing, is filling the pipes with pressurized water, or sand, or hydraullic fluid, and then bending the pipe. The pressure inside the piping doesn't allow for the pipe to pinch down anywhere, so instead, it stretches.

 

pretty simple actually. here are 3 kinds of bends:


in compression bending, the inside portion of the pipe is compressed, which makes it shorter, curving the pipe. this causes the inside portion to bunch up a bit, and even though it looks smooth, the interior diameter is reduced slightly.

in dimple bending, the inside endge of the pipe folds into little ridges. this is the worst way.

mandrel bend: basically, the outside portion of the piping is stretched, curving the pipe.

compression bendiing is ok for N/A applications under, say, 300 HP


[Modified by JDM LUDE, 5:52 AM 1/24/2002]