Polycrystalline diamond percussion drill bits using low thrust and torque for application with small diameter drill bits

1. A percussion drill bit, said drill bit formed having a body, the body capable of being secured with a drill shaft in preparation for a percussion drilling operation, the body having a center axis and a cutting face, the cutting face having a frontal flat face, and a beveled face extending outwardly radially therefrom, the body and the cutting face being integrally formed;

said drill bit formed of a double chisel design or modified double chisel design configuration;

said drill bit capable of operating at a machine torque pressure of less than 20 bar, and at a machine thrust pressure of less than 20 bar;

said frontal face and said beveled face having a series of openings provided therein, and inserts being press fitted within said openings in preparation for usage of the drill bit in said drilling operation, each of said inserts having a tip comprising a polycrystalline diamond coating;

select of said inserts providing a first set of inserts and others of said inserts forming a second set of inserts;

said first set of inserts having a first approximately linear alignment and offset from the center axis of said bit body, and said second set of inserts having a second approximately linear alignment and also offset from the center axis of said bit body, said first and second sets of inserts forming wings of a double chisel, the first and second alignments being at an angle relative to each other;

each insert provided in the cutting face of the drill bit positioned at a different radius from the center axis of said bit body than all of the other inserts provided upon said cutting face of the drill bit, each insert in the cutting face being non-tracking relative to all of the other inserts provided upon said cutting face of the drill bit;

said drill bit body having a gauge diameter between about 1¼″ inches to 3½″ inches;

each insert being of conical shape; and

each insert having a gripping portion of a diameter between about 0.300 inches to 0.520 inches, each insert having a grip length of between about 0.290 inches and 0.550 inches, and each tip of each insert having a length of between about 0.200 inches to 0.320 inches, and a conical surface of each tip formed at an angle from the insert grip portion of about 15° to 40° with the vertical of said inserts.

2. The percussion drill bit of claim 1 wherein the drill bit operating range for machine torque pressure is between about 8 to 15 bar, and the machine thrust pressure setting for drill bit operation is set between 12 and 20 bar.

3. The percussion drill bit of claim 2 wherein the drill bit operation for optimal percussion drilling provides a machine torque pressure setting at 12 bar, and a machine thrust pressure setting at 15 bar.

4. The percussion drill bit of claim 1 wherein the drill bit is formed of the double chisel design, and the bit body has a gauge diameter between about 1¼″ to 2¼″.

5. The percussion drill bit of claim 4 wherein the drill bit of double chisel design comprises four inserts provided upon the beveled face, and two inserts fitted within the frontal flat.

6. The percussion drill bit of claim 5 wherein the first and second sets of inserts each comprise at least three inserts.

7. The percussion drill bit of claim 1 wherein said drill bit is formed of the modified double chisel design and said drill bit body has a gauge diameter about 2½″ to 3½″.

8. The percussion drill bit of claim 7 wherein the drill bit of modified double chisel design comprises between four to six PCD inserts mounted in the beveled face, and from two to four PCD inserts mounted within the frontal flat face.

9. The percussion drill bit of claim 8 wherein the first and second sets of inserts each comprise at least four inserts.

10. The percussion drill bit of claim 9 wherein said inserts having a tip radius between about 0.100 inch to 0.165 inch.

11. The percussion drill bit of claim 1 wherein the polycrystalline diamond coating on each tip of each insert is 0.010-0.030 inch thick.

12. The percussion drill bit of claim 1 wherein the radius from the center axis of the drill bit for each insert provided within the frontal flat face is as set forth in the following chart:

Number of

frontal

flat face

Radius of each insert

Drill Bit Size

Inserts

from the center axis

1¼″-1⅝″

1

⅛″

1¾

2

3/16″- 5/16″ 

2″

2

⅜″- 7/16″

2¼

2

⅜″- 7/16″

2½

3

⅜″-½″

3.0

4

⅜″-½″- 13/16″-

3½

4

1.0″.

13. The percussion drill bit of claim 1 wherein each insert provided within the drill bit body having dimensions within the ranges as set forth as follows:

Range Claimed for Inserts

Range Dimensions

Overall Length of Insert

.500″-.650″

Diameter of Insert

.3000″-.4200″

Tip Length

.200″-.260″

Tip Angle

15.00°-35.00°

Tip Radius

.100″R-.145″R

Grip Length

.290″-.420″.

14. The percussion drill bit of claim 1 wherein each insert provided within the drill bit body having dimensions within the ranges as set forth as follows:

Range Claimed for Inserts

Range Dimensions

Overall Length of Insert

.600″-.785″

Diameter of Insert

.3900″-.4900″

Tip Length

.250″-.350″

Tip Angle

15.00°-35.00°

Tip Radius

.120″R-.155″R

Grip Length

.300″-.450″.

15. The percussion drill bit of claim 1 wherein each insert provided within the drill bit body having dimensions within the ranges as set forth as follows:

Range Claimed for Inserts

Range Dimensions

Overall Length of Insert

.625″-.785″

Diameter of Insert

.4800″-.5200″

Tip Length

.260″-.335″

Tip Angle

25.00°-40.00°

Tip Radius

.135″R-.170″R

Grip Length

.330″-.500″.