Patent ID: 7516585
Filing Date: 2009-04-14
Classification: E04B,E04C,Y10T

Abstract:
1. A roll-formed grid member for a suspended ceiling made from a single metal strip, the member being generally symmetrical about an imaginary central vertical plane and having a cross-section that includes a lower horizontal flange extending laterally on both sides of the central plane, the flange being formed of a double layer of said metal strip folded back on itself at each of its lateral extremities, a generally vertical stem formed of two layers of said metal strip, one stem forming layer on each side of said imaginary plane, said stem forming layers being fixed together to prevent relative longitudinal sliding movement therebetween and thereby increasing the torsional stiffness of the grid member from what would occur where said layers are free to slide relative to one another, said stem forming layers being in abutting contact in a zone, said contact zone being above any zone where said stem forming layers are substantially laterally separated, said stem forming layers being separated in a zone extending vertically from said flange to said contact zone to form a reinforcing bulb, said stem forming layers forming said reinforcing bulb being formed with laterally inward depressions in abutting contact with one another at regularly spaced locations, and said layers have aligned slots at said depressions to receive connectors of cross tees.