Multi-step drill with asymmetric step profiles
The present drill point arrangement includes a first and second land defined by a first and second flute, with a first cutting tip and a second cutting tip formed on the first and second lands respectively. The first cutting tip being positioned a first radial distance and the second cutting tip being positioned a second radial distance, each measured from the axis of rotation. The second cutting tip is positioned next in cutting tip sequence to the first cutting tip, and the second radial distance of the second cutting tip is greater than the first radial distance of the first cutting tip. Optionally, the first cutting tip is positioned a first axial distance and the second cutting tip is positioned a second axial distance, each measured from the front tip, and the second axial distance is greater than the first axial distance.
1 . A drill point arrangement comprising:
a drill point body comprising an acute geometry that is conical from a front tip to a base and having an axis of rotation;
a first flute extending from the front tip to at least the base;
a second flute extending from the front tip to at least the base;
a first land and a second land, the first land at least partially defined by the first flute and the second land at least partially defined by the second flute;
a first step is formed into the first land and comprises a first transverse step segment adjoining a first parallel step segment;
a first cutting tip at least partially defined by the first transverse step segment, the first parallel step segment, and the first flute, the first cutting tip being positioned a first radial distance measured from the axis of rotation, the first cutting tip being positioned a first axial distance measured from the front tip;
a second step is formed into the second land and comprises a second transverse step segment adjoining a second parallel step segment; and
a second cutting tip at least partially defined by the second transverse step segment, the second parallel step segment, and the second flute, the second cutting tip being positioned a second radial distance measured from the axis of rotation and a second axial distance measured from the front tip;
wherein the second cutting tip is positioned next in cutting tip sequence to the first cutting tip, and the second radial distance of the second cutting tip is greater than the first radial distance of the first cutting tip;
wherein the second axial distance of the second cutting tip is greater than the first axial distance of the first cutting tip; and
wherein the first cutting tip and the second cutting tip are arranged diametrically opposite and rotationally asymmetric to one another.
2 . The drill point arrangement of claim 1 wherein:
a first major cutting edge of the first step is defined by an intersection of the first transverse step segment and the first flute;
a first minor cutting edge of the first step is defined by an intersection of the first parallel step segment and the first flute;
the first cutting tip is further defined by an intersection of the first major cutting edge and the first minor cutting edge;
a second major cutting edge of the second step is defined by an intersection of the second transverse step segment and the second flute;
a second minor cutting edge of the second step is defined by an intersection of the second parallel step segment and the second flute; and
the second cutting tip is further defined by an intersection of the second major cutting edge and the second minor cutting edge.
3 . The drill point arrangement of claim 1 wherein:
a drill tip point is situated at the front tip of the drill point body and comprises a first primary cutting edge similar to and opposing a second primary cutting edge;
a first drill tip minor cutting edge extending rearward from the first primary cutting edge to the first major cutting edge, the first drill tip minor cutting edge being at least partially defined by the first land and the first flute; and
a second drill tip minor cutting edge extending rearward from the second primary cutting edge to the second major cutting edge, the second drill tip minor cutting edge being at least partially defined by the second land and the second flute, the second drill tip minor cutting edge being longer than the first drill tip minor cutting edge.
4 . The drill point arrangement of claim 3 wherein the first drill tip minor cutting edge is adjoining the first transverse step segment of the first step, and the second drill tip minor cutting edge is adjoining the second transverse step segment of the second step.
5 . The drill point arrangement of claim 1 wherein the first flute and the second flute are spirally arranged.
6 . The drill point arrangement of claim 1 wherein:
a first prior minor cutting edge is prior in cutting sequence to and adjoining the first major cutting edge;
a second prior minor cutting edge is prior in cutting sequence to and adjoining the second major cutting edge;
wherein the second axial distance of the second cutting tip is greater than the first axial distance of the first cutting tip due to at least one of the first major cutting edge being shorter than the second major cutting edge or the first prior minor cutting edge being shorter than the second prior minor cutting edge.
7 . The drill point arrangement of claim 1 wherein the second radial distance of the second cutting tip is greater than the first radial distance of the first cutting tip due to the first major cutting edge being shorter than the second major cutting edge.
8 . The drill point arrangement of claim 1 wherein:
a third cutting tip is at least partially defined by the first flute and the first land and is positioned next in cutting tip sequence to the second cutting tip, the third cutting tip being positioned a third radial distance measured from the axis of rotation, the third radial distance of the third cutting tip is greater than the second radial distance of the second cutting tip; and
a fourth cutting tip is at least partially defined by the second flute and the second land and is positioned next in cutting tip sequence to the third cutting tip, the fourth cutting tip being positioned a fourth radial distance measured from the axis of rotation, the fourth radial distance of the fourth cutting tip is greater than the third radial distance of the third cutting tip.
9 . The drill point arrangement of claim 8 wherein the third cutting tip is positioned a third axial distance measured from the front tip and the fourth cutting tip is positioned a fourth axial distance measured from the front tip, the fourth axial distance of the fourth cutting tip is greater than the third axial distance of the third cutting tip.
10 . The drill point arrangement of claim 8 wherein:
a fifth cutting tip is at least partially defined by the first flute and the first land and is positioned next in cutting tip sequence to the fourth cutting tip, the fifth cutting tip being positioned a fifth radial distance measured from the axis of rotation, the fifth radial distance of the fifth cutting tip is greater than the fourth radial distance of the fourth cutting tip; and
a sixth cutting tip is at least partially defined by the second flute and the second land and is in simultaneous cutting tip sequence with the fifth cutting tip, the sixth cutting tip being positioned a sixth radial distance measured from the axis of rotation, the sixth radial distance of the sixth cutting tip is equal to the fifth radial distance of the fifth cutting tip.
11 . The drill point arrangement of claim 10 wherein the fifth cutting tip is positioned a fifth axial distance measured from the front tip and the sixth cutting tip is positioned a sixth axial distance measured from the front tip, the sixth axial distance of the sixth cutting tip is equal to the fifth axial distance of the fifth cutting tip.
12 . The drill point arrangement of claim 1 wherein:
the first transverse step segment comprises a first truncated cone section and the first parallel step segment comprises a first cylindrical section, with the first truncated cone section adjoining the first cylindrical section; and
the second transverse step segment comprises a second truncated cone section and the second parallel step segment comprises a second cylindrical section, with the second truncated cone section adjoining the second cylindrical section.