Rotating machine tool and process for cutting gearwheels with asymmetrical teeth

A rotary cutting tool for generating asymmetrical teeth in a gear wheel, each tooth of the gear wheel having an active side (A) with a convex profile conjugated with the profile of a tooth of a counter gear wheel meshing with the gear wheel and a secondary concave side (S), the rotary cutting tool comprising:

• a cylindrical body extending along an axial direction of the tool;
• a helical toothing extending outward from the cylindrical body along the axial direction of the tool;
• wherein the helical toothing extends on a first side of a median section of the tool and a second side of the median section (M-M) of the tool, the median section (M-M) being defined as a cross-section perpendicular to the axial direction of the tool and configured to be intersected by a radius Rp of the gear wheel, said radius Rp being orthogonal to the rotation axis of the tool operating on the gear wheel to generate the teeth thereof;
• wherein each tooth of the helical toothing has a first side (CA) defining a first side cutting edge configured to generate said active side (A) of said gear wheel teeth, a second side (CS) defining a second side cutting edge configured to generate the secondary concave side (S), and a maximum height measured from a tip of the tooth to a base of the tooth at the cylindrical body;
• wherein a first pitch (P1) between the first side cutting edge of consecutive teeth of the helical toothing is constant;
• wherein a second pitch (P2) between the second side cutting edge of the consecutive teeth of the helical toothing is greater than the first pitch (P1) and variable along the axial direction of the tool;
• wherein, nearest to the median section (M-M) on the first side of the median section (M-M), the second pitch (P2) is greatest on the first side of the median section (M-M);
• wherein, on the second side of the median section (M-M), the second pitch (P2) is not greater than the second pitch (P2) nearest to the median section (M-M) on the first side of the median section (M-M);
• wherein, on the first side of the median section (M-M) of the tool, the second pitch (P2) decreases, and as the second pitch (P2) decreases a thickness of the helical toothing increases, respectively, the thickness of the helical toothing measured in a direction parallel to the axial direction;
• wherein, on the first side of the median section (M-M) of the tool, the maximum height between the consecutive teeth of the helical toothing in the axial direction is substantially constant over a first portion of said helical toothing between a first end of the helical toothing and the median section (M-M);
• and
• wherein, on the second side of the median section (M-M) of the tool, the maximum height between the consecutive teeth of the helical toothing in the axial direction decreases over a second portion of said helical toothing between the median section (M-M) and a second end of the helical toothing, the second end being opposite the first end.