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348,183. Making expanded metal. WHITE, A. E., 5, Quality Court, Chancery Lane, London.- (Kalman Steel Co. ; Wrigley Building, Chicago, U.S.A.) Feb. 8, 1930, No. 4332. [Classes 83 (ii) and 83 (iv).] Expanding and stretching dies; shearing ; rolling.-In making joists &c. of expanded metal a blank having side flanges joined by a web is passed between rollers which slit the web by a nipping action, the blank then being passed through a die which separates the flanges and causes the web to be expanded without increasing the length of the flanges and the attached web parts. A blank having flanges F and a web W is formed by rolling in the usual manner at a temperature of about 1600‹ F. and may be passed directly to the slitting rolls 20, 21, or if allowed to cool is reheated in a furnace A before slitting. The slits are formed by ribs 22 on the rolls 20, 21, Fig. 3, which penetrate without displacing the metal from the plane of the web, clearances at the bases of the ribs receiving the metal displaced by their penetration. The expansion is preferably performed by a die 33 having a clearance space 35, Fig. 4, for the web and diverging ribs 37 which act on the inner surfaces of the flanges to progressively spread them apart as the beam is drawn through. Clearances 38 are provided at the outer surfaces of the flanges and are considerable in the tapered portion of the die to reduce friction but become less in the final parallel portion. The ribs 37 extend towards the slitting rolls beyond the remainder of the die and have upper and lower shoes at the forward end for guiding the flanges F. In passing through the parallel portion of the die the flanges are smoothed and set definitely in a parallel relation. On emergence from the die upper and lower finishing rolls 41 act on the expanded web to set the struts accurately in a plane, the rolls 41, 20, 21 being positively driven for feeding. The web may be given more or less than the three rows of slits shown in Fig. 3.
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