| 摘要 |
520,333. Marking bars. LUKACS, E.. and STERN, S. Sept. 19, 1938, No. 27315. Convention date, Oct. 9, 1937. [Class 20 (iv)] [Also in Group XXII] In raising the yield point and tensile strength of rods for reinforced concrete by cold working by applied torsion, the strength is indicated by the pitch of small intermittent depression or colour on a line parallel to the axis of the bar which has been distorted to helical form by the applied torsion. In the Figure, gripping jaws 5 apply a straight pull to draw a rod g through a pair of skew rolls 6, 7 provided with a surface to make grooves on the rod such groove &c. emerging as a helical pattern &c., the pitch of which is proportional to the torsion applied by the rolls. In a modification, the roll pair may be parallel, the torsion being applied by rotating the roll pair round the axis of the bar or by turning the gripping jaws round in addition to their pull. An automatic disconnector may cut off the applied torsion when the required strength is attained as indicated by the helical pitch on the rod. The torsion may be varied along different lengths of a rod to vary the strength longitudinally. |
