As a specialty bender roller, we see a lot of domes come to us for estimating. One of the recent projects that came through to us was this dome trellis pictured below. The interesting piece about this project – it was designed using aluminum material. The dome trellis used a variety of rolled, rectangular tubes to create the shape and was likely designed out of aluminum to minimize the weight of the trellis frame.
Rolling aluminum tubes can be challenging due to the material’s physical properties. Bending the straight tubes to create an arc with the specific radius requires several passes through the machine. With each pass, the aluminum material gets harder and more brittle. This may eventually lead to material failure like the aluminum cracking. To prevent this from happening, the correct material thickness is extremely important. Another way to improve the success of aluminum rolling is to send the material out for stress relief.
For this dome trellis, 6” x 3” aluminum tubes were chosen for the rafters and those were to be rolled the hard way. This means bending a section against the strong (x-x) axis. A rectangular bar was also bent the hard way into a circle. Imagine a giant metal washer – that what this piece would look like.
In addition to those sizes, 8” x 4” and 6” x 2” aluminum tubes were chosen for the purlins, the horizontal supports for the trellis dome. Those were to be rolled the easy way, which means bending a section against the weak (y-y) axis. A rectangular bar was bent the easy way into a circle. Imagine this piece would look like a belt.
To create this incredible dome trellis, all the aluminum tubes were rolled to different radii.