Re: cnc tube bender

Hello,

Adding to what Doug already posted:

There is a feeder, like the barfeed of a lathe. The pipe/tube is
advanced and/or rotated towards the bender at one end of the machine.
There is a MINIMUM radius bending support wheel of the correct size
for the tubing being formed, (It has a coved edge to match the
tubing). The bender itself is much like a manual type used in many
shops, but is usually hydraulic.(some are electric.) It clamps the
tube between the radius wheel and a "shoe" (which is similarly coved
on its edge, but is straight otherwise.)

After clamping, the shoe rotates around the wheel bending the tube
(it's at the end of an arm,with its pivot point at the center of the
wheel). How far is determined by the cnc. As the bend is made the
feeder advances in sync with the "used up" length. The clamp shoe
releases, and the stock is advanced and rotated (if need be) to the
next bend point, and the process repeats...

The machines I've seen at trade shows were in the $135K range. The
software was pretty nice, it kinda looked like that "pipes"
screensaver; you told it distance and rotations, and angles, and
it "grew" the part on screen. Very simple programming.

And any bend of larger radius than the minimum set by the wheel, is
done the same way we sometime do arcs and ellipses; by a series of
short bends which combine for the desired curve radius.

The feeder DOES have different internal "collets" to hold the various
sizes of tube for the forming process. Every machine I saw in
operation was hand loaded one "stick" at a time; but I know that
automatic multi tube feeders are available, just like lathe barfeeds.

Hope this helps,

Ballendo

P.S. About a year ago, I was looking into making an inexpensive one
of these for the model train and jewelry market. It's a VERY "do-
able" thing on this small scale. Automating a shop size bender
wouldn't be much tougher; the hardest part is having enough force to
bend the large stock, accurately controlled enough to not over or
under bend. My approach was gonna be to use a stepper to set a STOP,
and just use hydraulic up TO the stop, like a limit switch. Change
the switch location, and you change the bend angle. The other two
axes are easy. One is just a long linear feed; and the other is
rotation around the feed axis. As I said, pretty do-able...




--- In CAD_CAM_EDM_DRO@yahoogroups.com, penn king <pennkingN@n...>
wrote:

> Does anybody here have any experience with or knowledge of cnc

tube/pipe

> benders? Besides a plasma machine, a cnc tube bender would really

be the

> ticket. can anyone describe the basic system?
> Thanks to all.
> Cordially,
> Penn King
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