Drill point for one-shot drilling of sandwich panels and similar

1. A drill point ( 1 ) for drilling sandwich panels ( 100 ), composite materials and similar, comprising:

a shank ( 2 ) for coupling into the chuck a tool apt to drive said point ( 1 ) in rotation;

a drilling member, integral to said shank, comprising:

a substantially cylindrical working portion ( 3 ),

a cutting head ( 4 ), located at the end of said working portion ( 3 ), having cutting edges (C);

wherein onto the surface of said working portion ( 3 ) there are obtained helical flutes ( 5 ), spirally arranged about a substantially central longitudinal axis (A-A) of said working portion ( 3 ), said flutes ( 5 ) ending on a top face ( 4 ′) of said cutting head ( 4 ),

characterized in that the constructive geometry thereof provides:

a helix angle (ε) with respect to said longitudinal axis (A-A), along which there develop said helical flutes ( 5 ), substantially comprised in a range of 30° to 35°;

a chisel edge angle (η) substantially comprised in a range of 1° to 5°;

a first radial relief angle (γ r ) substantially of 7°;

a second external relief angle (α) substantially comprised in a range of 22° to 26°;

an inferior relief angle (δ) of said helical flutes ( 5 ) on said cutting head ( 4 ) with respect to said longitudinal axis (A-A) substantially of about 25°;

a section of said cutting head ( 4 ), commonly known as face ( 6 ), for raising and letting flow a chip deriving from the drilling action, having length (L 6 ) substantially comprised in a range of 0.3 to 0.5 mm;

an angle (θ) included between said face ( 6 ) and the relief ( 7 ) of said flutes ( 5 ) on said head ( 4 ) substantially comprised in a range of 70° to 80°;

a central core ( 8 ) of said point ( 1 ) with diameter (D 8 ) substantially comprised in a range of 1.5 mm to 2.7 mm;

a sharpening angle (β) of the head ( 4 ) of said point ( 1 ) substantially comprised in a range of 110° to 150°;

so as to carry out a one-shot drilling of said sandwich panels ( 100 ), composite materials and similar.

2. A drill point ( 1 ) according to claim 1 , wherein said sharpening angle (β) is of 130°.

3. A drill point ( 1 ) according to claim 1 , further comprising lubrication-cooling channels, defining paths extending along at least part of said substantially cylindrical working portion ( 3 ) and having outlet ( 20 ) in correspondence of said cutting head ( 4 ).

4. A drill point ( 1 ) according to claim 1 , wherein said drilling member comprises a countersink portion ( 12 ), in a position substantially opposite to said cutting head ( 4 ).

5. A drill point according to claim 4 , wherein said countersink portion ( 12 ) has a countersink angle (λ) substantially of 100°.

6. A drill point ( 1 ) according to claim 1 , of micrograin-submicrograin hard metal.

7. A drill point according to claim 1 , wherein:

said shank ( 2 ) has diameter (D 2 ) comprised in a range of 6 to 20 mm and length (L 2 ) comprised in a range of 25 to 100 mm; and

said substantially cylindrical working portion ( 3 ) comprises a first structural reinforcement part ( 3 R ) onto which said helical flutes ( 5 ) relieve topwise, optionally apt to make said countersink ( 12 ), having a diameter (D 3R ) comprised in a range of 11-20 mm and a length (L 3R ) comprised in a range of 15 to 25 mm; and a second penetrating part ( 3 P ) having a diameter (D 3P ) comprised in a range of 3 to 10 mm and a length (L 3P ) comprised in a range of 8 to 47 mm.

8. A drilling tool comprising a drill point ( 1 ) such as introduced in claim 1 .