Multiple rotary knife for longitudinal splitting of webs

A multiple rotary knife for longitudinal splitting of webs, comprising:

• a generally cylindrical annular body bearing a plurality of circumferential blades spaced apart, wherein said circumferential blades are formed by continuous hard-metal rings mechanically fixed axially to said annular body;
• wherein each hard-metal ring has at least one cutting flank, said at least one cutting flank having an oblique portion inclined by an angle comprising between 1° and 10° relative to a longitudinal axis of the knife;
• an outermost radial surface of said ring being parallel to the longitudinal axis of the knife, said oblique portion being oblique relative to said outermost surface;
• said at least one cutting flank having an initial stretch orthogonal to the longitudinal axis of the knife and said initial stretch having a longitudinal dimension shorter than said oblique portion of said at least one cutting flank, said initial stretch being immediately adjacent to said outermost radial surface of said hard-metal ring opposite said annular body;
• said initial stretch perpendicular to said outermost surface;
• said oblique portion extending from said initial stretch obliquely relative to said initial stretch.