Friday, December 16, 2011

Q&A: Can you tell me more about curving?

We recomend a custom submittal drawing be used for curved diffusers when you have a custom curving need.  The submittal files are used both by a curving vendor and at receiving plants to ensure accuracy.
Custom curving requires that the customer specify the border style, direction of curve (whether plan - ceiling or floor installs or face curves - arches), radius and length.
Custom curving is best performed using precision stretch-forming techniques developed for the aeronautical industry.  They are generally more accurate and faster than roll-forming techniques.
How Exactly Does s Stretch Forming Work?

Stretch forming allows material to be formed along a custom template while eliminating wrinkling along the inside edges of the curve.

Aluminum is the most commonly used, but other metals can be stretch formed. Stretch forming is a process that permanently bends metal into a desired shape using heat to treat it then press it over a die while the metal is held at a tension beyond the yield point.

When the metal is held just beyond the yield point it will permanently retain the desired contour and shape. Some materials may require multiple stretching operations to permanently alter the memory of the metal.
A. Both ends of the work material are inserted in gripper jaws that are mounted on a swing-arm.
B. The material is then stretched outward to its yield point.
C. Then wrapped around the form die while maintaining the stretch force.
D. When the metal has taken shape, the force is released and the finished curved product is removed. The material’s memory has been permanently altered to the desired shape.

Mark Costello - GRD Application Engineering Manager

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