Iron sheet building roofing - is made by feeding sheet edges into cooperating beams and subjecting them to longitudinal tension

摘要

The iron sheeting for use as roofing is made by unrolling a predetermined length of iron sheet and forming projections at regular intervals on the two opposite edges. The edges are threaded and secured into two pairs of longitudinally spaced beams (9-12) on either side of the sheet which locate behind the projections. Two rams (14,15) act on the ends of adjacent beams, placing the sheet under longitudinal tension and compressing them down onto the edges of the sheet. When the rams are released, the sheet is cut transversely to form two sections of prestressed sheeting.