Are manufactured from thin sheet materials.
Lobster back bend sheet metal.
One type of industrial component i have been involved with the design and manufacture of is lobster back bends.
Ducts have circular cross sectional shape.
With all segments connected final bend will have everything line up properly.
As with all standard lobster back bends the start and finish segments are basically a normal segment cut in half.
Calculation flat pattern used as a template for cutting the pipe producing with wall thickness s 0.
Calculator will calculate the necessary dimensions for the construction flat pattern segments lobsterback bend elbow tee piece frustum cone and truncated pipe truncated cone with an accessible vertex and triangulation method.
Many articles such as cans pipes elbows boxes ducting hoppers etc.
Duct size remains constant between inlet and outlet.
This type of duct bend is made up of segments cut from flat sheets or plates rolled into cylindrical parts then assembled.
The location of the segment seam see image of finished bend assists the fabricator in lining up the parts to assemble the bend.
Technical description lobster provides a multi gored bend between two ducts.
It depends how much material frame cut forming welding cost in your shop.
From 2 to 10 gores permitted.
We start off by modeling sheet metal cylinder diameter same as required duct diameter.
Generally a template is produced from an orthographic drawing when small quantities are required larger quantities may justify the use of press tools and the template will include allowances for bending and seams bearing in mind the thickness of material used.
On light gauge sheet metal you could bend by hand after rolling.
These can be light sheet metal or manufactured from thick plate.