Drill Head for Deep-Hole Drilling

Abstract

Provided is a drill head for deep-hole drilling which does not generate such a disc that clogs a cutting chip discharge port when a head main body of the drill head penetrates a work material. The drill head is mounted with a central cutting blade tip 6 at the head center portion so as for a blade edge 6 a thereof to be inclined downward toward the head center portion, a circumferential cutting blade tip 7 at a circumferential portion so as for a blade edge 7 a thereof to be inclined upward toward the head center portion, and an intermediate cutting blade tip 8 therebetween so as for a blade edge 8 a thereof to be inclined upwardly and inwardly toward the head center portion, while the cutting blade tips face a cutting chip discharge port 4 or 5 . The drill head includes a head main body 2 having an interior hollow portion 3 serving as a cutting chip discharge passage which communicates with the discharge ports 4 and 5 . A disc breaker 12 composed of a surface inclined downwardly and inwardly toward the head center portion is formed at a head center side end portion of a flank 8 b of the intermediate cutting blade tip 8.

1 . A deep-hole drilling drill head comprising:
 a head main body having a forward end and a rotation axis (G) extending through a head center portion thereof;   at least one cutting chip discharge port opened at a distal end surface of the head main body;   a central cutting blade tip mounted at the head center portion so as for a blade edge thereof to be inclined downwardly and inwardly toward the head center portion;   a circumferential cutting blade tip mounted at a circumferential portion so as for a blade edge thereof to be inclined upwardly and inwardly toward the head center portion;   an intermediate cutting blade tip mounted between the central and circumferential cutting blade tips, the intermediate cutting blade tip having a blade edge inclined upwardly and inwardly toward the head center portion, the central cutting blade tip, the circumferential cutting blade tip and the intermediate cutting blade tip each facing the at least one cutting chip discharge port;   an interior of a hollow portion of the head main body serving as a cutting chip discharge passage communicating with the at least one cutting chip discharge port; and   a disc breaker provided at a head center side end portion of a forward facing flank of the intermediate cutting blade tip, the disc breaker extending along at least an overlapping region (OL) where the intermediate cutting blade tip circumferentially overlaps with the central cutting blade tip, the disc breaker comprising a surface that is inclined downwardly and inwardly toward the head center portion.   
     
     
         2 . The deep-hole drilling drill head according to  claim 1 , wherein the disc breaker forms a first angle (θ) with respect to a plane (Q) orthogonal to the rotation axis (G), said first angle (θ) being in the range of 0 to 60 degrees. 
     
     
         3 . The deep-hole drilling drill head according to  claim 2 , wherein said first angle (θ) is about 20 degrees. 
     
     
         4 . The deep-hole drilling drill head according to  claim 2 , wherein the upwardly and inwardly inclined blade edge of the intermediate cutting blade tip forms a second angle (α) with respect to a plane (Q) orthogonal to the rotation axis (G), said second angle (α) being about 20 degrees. 
     
     
         5 . The deep-hole drilling drill head according to  claim 1 , wherein the disc breaker extends along an expanded region (M) which comprises the aforementioned overlapping region (OL) plus an additional region which extends in a direction away from the head center portion and the rotation axis G. 
     
     
         6 . The deep-hole drilling drill head according to  claim 5 , wherein, along the entire expanded region (M), the disc breaker forms a first angle (θ) with respect to a plane (Q) orthogonal to the rotation axis (G), said first angle (θ) being in the range of 0 to 60 degrees. 
     
     
         7 . The deep-hole drilling drill head according to  claim 6 , wherein the upwardly and inwardly inclined blade edge of the intermediate cutting blade tip forms a second angle (α) with respect to a plane (Q) orthogonal to the rotation axis (G), said second angle (α) being about 20 degrees. 
     
     
         8 . The deep-hole drilling drill head according to  claim 1 , wherein:
 the forward facing flank of the intermediate cutting blade tip comprises a major flank surface which is inclined upwardly and inwardly toward the head center portion, and a minor flank surface which is inclined downwardly and inwardly toward the head center portion;   the major flank surface is connected to the minor flank surface at a ridge; and   the minor flank surface constitutes the disc breaker.   
     
     
         9 . The deep-hole drilling drill head according to  claim 8 , wherein:
 the major flank surface is associated with the upwardly and inwardly inclined blade edge;   the minor flank surface forms a first angle (θ) with respect to a plane (Q) orthogonal to the rotation axis (G), said first angle (θ) being in the range of 0 to 60 degrees; and   the major flank surface forms a second angle (α) with respect to a plane (Q) orthogonal to the rotation axis (G), said second angle (α) being about 20 degrees.   
     
     
         10 . A deep-hole drilling drill head comprising:
 a head main body having a forward end and a rotation axis (G) extending through a head center portion thereof;   at least one cutting chip discharge port opened at a distal end surface of the head main body;   a central cutting blade tip mounted at the head center portion so as for a blade edge thereof to be inclined downwardly and inwardly toward the head center portion;   a circumferential cutting blade tip mounted at a circumferential portion so as for a blade edge thereof to be inclined upwardly and inwardly toward the head center portion;   an intermediate cutting blade tip mounted between the central and circumferential cutting blade tips, the intermediate cutting blade tip having a blade edge inclined upwardly and inwardly toward the head center portion, the central cutting blade tip, the circumferential cutting blade tip and the intermediate cutting blade tip each facing the at least one cutting chip discharge port;   an interior of a hollow portion of the head main body serving as a cutting chip discharge passage communicating with the at least one cutting chip discharge port;   wherein:   the intermediate cutting blade tip has a forward facing flank comprising:
 major flank surface associated with the blade edge and inclined upwardly and inwardly toward the head center portion; and 
 a minor flank surface connected to the major flank surface and inclined downwardly and inwardly toward the head center portion, the minor flank surface being closer to the rotation axis than the major flank surface; and 
   the minor flank surface constitutes a disc breaker which extends along at least an overlapping region (OL) where the intermediate cutting blade tip circumferentially overlaps with the central cutting blade tip.   
     
     
         11 . The deep-hole drilling drill head according to  claim 10 , wherein the disc breaker forms a first angle (θ) with respect to a plane (Q) orthogonal to the rotation axis (G), said first angle (θ) being in the range of 0 to 60 degrees. 
     
     
         12 . The deep-hole drilling drill head according to  claim 11 , wherein said first angle (θ) is about 20 degrees. 
     
     
         13 . The deep-hole drilling drill head according to  claim 11 , wherein the upwardly and inwardly inclined blade edge of the intermediate cutting blade tip forms a second angle (α) with respect to a plane (Q) orthogonal to the rotation axis (G), said second angle (α) being about 20 degrees. 
     
     
         14 . The deep-hole drilling drill head according to  claim 10 , wherein the disc breaker extends along an expanded region (M) which comprises the aforementioned overlapping region (OL) plus an additional region which extends in a direction away from the head center portion and the rotation axis G. 
     
     
         15 . The deep-hole drilling drill head according to  claim 14 , wherein, along the entire expanded region (M), the disc breaker forms a first angle (θ) with respect to a plane (Q) orthogonal to the rotation axis (G), said first angle (θ) being in the range of 0 to 60 degrees. 
     
     
         16 . The deep-hole drilling drill head according to  claim 15 , wherein the upwardly and inwardly inclined blade edge of the intermediate cutting blade tip forms a second angle (α) with respect to a plane (Q) orthogonal to the rotation axis (G), said second angle (α) being about 20 degrees. 
     
     
         17 . The deep-hole drilling drill head according to  claim 10 , wherein:
 the major flank surface is connected to the minor flank surface at a ridge.   
     
     
         18 . The deep-hole drilling drill head according to  claim 10 , wherein:
 the minor flank surface forms a first angle (θ) with respect to a plane (Q) orthogonal to the rotation axis (G), said first angle (θ) being in the range of 0 to 60 degrees; and   the major flank surface forms a second angle (α) with respect to a plane (Q) orthogonal to the rotation axis (G), said second angle (α) being about 20 degrees.