| 摘要 |
<p>1405067 Concrete-reinforcing bars KORF INDUSTRIE UND HANDEL GmbH & CO KG 26 March 1973 [27 March 1972] 14325/73 Heading E1K [Also in Division B3] A concrete reinforcing bar is produced from i steel bar in two cold rolling passes, the first providing the bar with a curved triangular cross section, Figure 1, and the second with inclined ribs 11-13, Figure 2. The ribs blend at their ends into the bar surface and have an outer envelope of circular form, when projected axially of the bar. The second pass is offset 60‹ relative to the first, so that the corners of the triangular cross section provide the ribs. The ratio of the radii r v2 , Fig. 1, of the curved sides of the triangle and r v1 of the inscribed circle is between 1.6 and 2.4, and the radius r v1 is not greater than the dimension K R , Figure 2. The method can produce bars with final diameters of from 4 to 12mm., but when the initial bar stock is not suited to the first pass, an equalizing drawing or rolling pass is made before the first pass. In some cases, two equalizing rolling passes may need to be made. The ribs may be inclined to the bar axis by from 45 to 60‹, have a crest width of 0.15 or 0.20 mm., and a height of 5.6 to 7.5% of the nominal diameter.</p> |
