Concrete reinforcement rods

Claim 1

Apparatus for rolling a rod into a reinforcing rod for concrete and for forming laterally spaced cold rolled serpentine ribs on the outer surface of the rod which ribs extend generally in the axial direction of the rod, comprising a plurality of rolls each mounted for rotation about an axis and each said roll having a calibrating surface formed on and extending around the outer circumference thereof and said calibrating surface arranged to contact the outer surface of the rod, said rolls positioned angularly apart forming a pass therebetween for the rod with the calibrating surfaces of said rolls defining the pass, each said calibrating surface having a pair of spaced circumferentially extending edges along each of the opposite sides of the calibrating surface, each said roll having a pair of cheeks extending transversely of the axis of said roll and a flank extending between each said cheek and the adjacent edge of said calibrating surface, said flanks extending outwardly from the pass formed by said rolls and adjacent said flanks on the adjacent surfaces of said rolls being disposed in spaced relation forming an open gap between adjacent rolls extending outwardly from said pass wherein the ribs are formed on the rod, said calibrating surface on each said roll having a circumferential center line spaced equidistantly from its edges and the edges of said calibrating surface having a continuously varying dimension from said circumferential center line alternating periodically in a regular repetitive manner between a maximum and a minimum spacing.