Re: Square Tube bending

Are you trying to bend thin wall or structural tubing? Generally,
the thinner the wall, the more rippling and collapse you will have
when not using a mandrel. As others have stated, the inside is in
compression, so rippling can occur, and the outside in tension, so
stretching and outside wall collapse occurs. Another effect is the
top to bottom dimension of the tube will grow, but only in the inner
half of the tube section. This can cause wedging of the part in the
die, so a release mechanism may be required. If using a Pines type
hydraulic bender, the clamp bar will have a lip extending from it's
face that slides on top of the tube, and under the top lip of the
die, defining the top to bottom dimension of the final shape. When
the bend is complete, the clamp pulls back, and the lip pulls out of
engagment, releasing the part. Another methode is to have the top
lip of the die separate, and let it loose to remove the part.
The key to good square/rectangular tube bending is controlling the
shape in the bend zone, and not forcing the radius too tight that the
tube rips. We generally use 3X tube dimension in the plane of bend
for cold/hydraulic bending (ex. 2 x 4 x 1/4 tube will have a 6"R die
in the Easy plane).

Allan

--- In CAD_CAM_EDM_DRO@y..., jvicars@c... wrote:
> Is there anything special about dies for bending Square tubing?
> There seems to be very few people who know anything about bending
> square tubing.
> Anyone know where I can find info on this? I want to build a set
of
> my own dies for one specific project.
>
> Thanks.