Forming roll for rolling cylindrical bodies from cylindrical rod stock, and a method of making the same

A forming roll for forming cylindrical metal slugs from cylindrical rod stock, comprising a helical groove having a cylindrical base portion of constant radius and substantially constant axial length, said groove being defined by a helical rib of progressively increasing height for parting said rod stock into slugs, said helical rib having leading and trailing flanks of which the pitch is changed progressively along the axial length of the roll in stages including a first stage occupying an arc of not more than 360.degree. wherein the pitch of the trailing flank of the rib is smaller than the pitch of the remainder of said trailing flank, and a second stage wherein the pitch of the leading flank has a smaller pitch than that of the trailing flank whereby the axial length of the helical rib is increased along the axis of the roll, and wherein the said pitch of the trailing flank in the first stage and the said pitch of the leading flank in the second stage are approximately the same and the respective portions of said flanks are axially opposed to one another, whereby the increase in axial length of the said rib is accommodated substantially without reduction in the axial length of the helical groove.