Impregnated rotary bit with high density monoblock center structure
A drill bit includes a bit body having an end face for engaging a rock formation. The end face is defined by a HIP pressed center structure formed of a metal matrix impregnated with super abrasive particles. The HIP pressed center structure includes a central region located at a center axis of said drill bit and finger regions extending radially from the central region. The end face is further defined by infiltrated ribs formed of a metal matrix impregnated with super abrasive particles. Certain ones of the infiltrated ribs are configured to form radial extensions from the finger regions of the HIP pressed center structure.
1. A drill bit, comprising:
an outer gage;
a bit body having an end with a conical inner region and a shoulder disposed between the conical inner region and the outer gage;
a cutting face attached to the end of the bit body and comprising:
a monoblock insert contained within the conical inner region, formed of a first metal matrix impregnated with super abrasive particles, and having a central region occupying a center of the cutting face and a plurality of finger regions extending from the central region;
a plurality of ribs extending outwardly from the monoblock insert to the outer gage and formed of a second metal matrix impregnated with super abrasive particles; and
a plurality of fluid channels formed between adjacent ribs,
wherein:
the monoblock insert has a density and a hardness greater than a density and a hardness of the ribs, and
some of the ribs correspond to the finger portions such that each corresponding rib is aligned with and has an end located adjacent to the respective finger region.
2. The drill bit of claim 1 , further including a plenum formed in the bit body, the central region of the monoblock insert including a center opening in fluid communication with the plenum via a central passage formed in the bit body.
3. The drill bit of claim 2 , further including a fluid channel formed in the monoblock insert and extending outwardly from the center opening.
4. The drill bit of claim 3 , wherein the fluid channel of the monoblock insert is in fluid communication with one of the fluid channels formed between the ribs.
5. The drill bit of claim 4 , further including a plurality of exit passages formed in the cutting face between the monoblock insert and the ribs, the exit passages in fluid communication with the plenum via offset passages formed in the bit body.
6. The drill bit of claim 1 , wherein the finger regions and the ribs are each radially extending.
7. The drill bit of claim 1 , wherein the finger regions and the ribs are each spirally extending.
8. The drill bit of claim 1 , wherein the density of the monoblock insert ranges between 1.13-1.19 times the density of the ribs.
9. The drill bit of claim 1 , wherein the hardness of the monoblock insert ranges between 1.18-1.35 times the hardness of the ribs.
10. The drill bit of claim 1 , further comprising a plurality of cutting inserts mounted along each of the ribs, wherein each of the inserts is impregnated with super abrasive particles.
11. The drill bit of claim 10 , wherein a height of the monoblock insert at a distal end of each finger portion corresponds to an exposure height of a respective adjacent one of the cutting inserts.
12. The drill bit of claim 1 , wherein a width of each finger portion at a distal end thereof matches a width of the respective corresponding rib.
13. The drill bit of claim 1 , further comprising a plurality of rib extensions extending along the outer gage.
14. The drill bit of claim 13 , wherein a number of the rib extensions is less than a number of the ribs such that a gap is formed along the outer gage.