Claims
- 1. A roof drill bit comprising:
- a tool body having a cutting insert affixed thereto, said cutting insert having one face, an opposite face, and a side surface joining said one face and said opposite face;
- said side surface having a leading side relief portion adjacent to the one face and a trailing side relief portion adjacent to the opposite face, said leading side relief portion being relieved at an angle so that the interior angle between the one face and the leading side relief portion is less than 90 degrees, said trailing side relief portion being relieved to a greater degree than said leading side relief portion; and
- said leading side relief portion extending from the one face a distance of between about one-third to about two-thirds the thickness of the cutting insert, and said trailing side relief portion extending from the opposite face a distance of between about one-third to about two-thirds the thickness of the cutting insert.
- 2. The roof drill bit of claim 1 wherein the leading side relief portion extends from the one face a distance of about one-half the thickness of the cutting insert.
- 3. The roof drill bit of claim 1 wherein the trailing side relief portion is relieved at an angle of between about 10 degrees to about 30 degrees.
- 4. The roof drill bit of claim 1 wherein the leading side relief portion is relieved at an angle of about 5 degrees, and the trailing side relief portion is relieved at an angle of about 22 degrees.
- 5. The roof drill bit of claim 1 wherein a layer of polycrystalline diamond covers one of said faces.
- 6. A roof drill bit comprising:
- a tool body having a cutting insert affixed thereto, said cutting insert having one face, an opposite face, and a side surface joining said one face and said opposite face;
- said side surface having a leading side relief portion adjacent to the one face and a trailing side relief portion adjacent to the opposite face, said trailing side relief portion being relieved to a greater degree than said leading side relief portion; and
- said leading side relief portion extending from the one face a distance of between about one-third to about two-thirds the thickness of the cutting insert, and said trailing side relief portion extending from the opposite face a distance of between about one-third to about two-thirds the thickness of the cutting insert, wherein the side surface further includes a mediate side relief portion between the leading side relief portion and the trailing side relief portion, and said mediate side relief portion being relieved at an angle that is greater than the angle of relief of the leading side relief portion and less than the angle of relief of the trailing side relief portion.
- 7. A cutting insert for a roof drill bit, the insert comprising:
- one face, an opposite face, and a side surface joining said one face and said opposite face;
- said side surface portion having a leading side relief portion adjacent to the one face and a trailing side relief portion adjacent to the opposite face, said leading side relief portion being relieved at an angle so that the interior angle between the one face and the leading side relief portion is less than 90 degrees, said trailing side relief portion having a relief angle that is greater than the relief angle of said leading side relief portion; and
- said leading side relief portion extending from the one face a distance of between about one-third to about two-thirds the thickness of the cutting insert, and said trailing side portion extending from the opposite face a distance of between about one-third to about two-thirds the thickness of the cutting insert.
- 8. The cutting insert of claim 7 wherein the relief angle of the trailing side relief portion is between about 10 degrees and about 30 degrees.
- 9. The cutting insert of claim 7 wherein a layer of polycrystalline diamond covers one of said faces.
- 10. A cutting insert for a roof drill bit, the insert comprising:
- one face, an opposite face, and a side surface joining said one face and said opposite face;
- said side surface portion having a leading side relief portion adjacent to the one face and a trailing side relief portion adjacent to the opposite face, said trailing side relief portion having a relief angle that is greater than the relief angle of said leading side relief portion; and
- said leading side relief portion extending from the one face a distance of between about one-third to about two-thirds the thickness of the cutting insert and said trailing side portion extending from the opposite face a distance of between about one-third to about two-thirds the thickness of the cutting insert, wherein the side surface further includes a mediate side relief portion between the leading side relief portion and the trailing side relief portion, and said mediate side relief portion being relieved at an angle that is greater than the relief of the leading side relief portion and less than the angle of relief of the trailing side relief portion.
- 11. An excavating tool comprising:
- a tool body having a cutting insert affixed to the axially forward end thereof;
- said cutting insert having one face, an opposite face, and a pair of side surfaces joining said faces;
- each one of said side surface portions having a leading side relief portion and a trailing side relief portion, said leading side relief portion being relieved at an angle so that the interior angle between the one face and the leading side relief portion is less than 90 degrees, said trailing side relief portion having a relief angle greater than the relief angle of said leading side relief portion; and
- said leading side relief portion extending from the one face a distance of between about one-third to about two-thirds the thickness of the cutting insert, and said trailing side portion extending from the opposite face a distance of between about one-third to about two-thirds the thickness of the cutting insert.
- 12. The excavating tool of claim 11 wherein the leading side relief portion extends from the one face a distance of about one-half the thickness of the cutting insert.
- 13. The excavating tool of claim 4 wherein the leading side relief portion has a relief angle of about 5 degrees, and the trailing side relief portion has a relief angle of about 22 degrees.
- 14. An excavating tool comprising:
- a tool body having a cutting insert affixed to the axially forward end thereof;
- said cutting insert having one face, an opposite face, and a pair of side surfaces joining said faces;
- each one of said side surface portions having a leading side relief portion and a trailing side relief portion, said trailing side relief portion having a relief angle greater than the relief angle of said leading side relief portion; and
- said leading side relief portion extending from the one face a distance of between about one-third to about two-thirds the thickness of the cutting insert, and said trailing side portion extending from the opposite face a distance of between about one-third to about two-thirds the thickness of the cutting insert wherein the side surface further includes a mediate relief portion between the leading side relief portion and the trailing side relief portion, and said mediate relief portion having a relief angle that is greater than the relief angle of the leading relief portion and less than the relief angle of the trailing relief portion.
- 15. A method of drilling a hole in earth strata comprising the steps of:
- positioning a tool including a rotary drill bit having a cutting insert against the earth strata, the cutting insert having one face, an opposite face and a pair of side surfaces joining said faces; each one of said side surface portions having a leading side relief portion and a trailing side relief portion, said leading side relief portion being relieved at an angle so that the interior angle between the one face and the leading side relief portion is less than 90 degrees, said trailing side relief portion being relieved to a greater degree than said leading side relief portion; and said leading side relief portion extending from the one face a distance of between about one-third to about two-thirds the thickness of the cutting insert, and said trailing side portion extending from the opposite face a distance of between about one-third to about two-thirds the thickness of the cutting insert; and
- rotating the rotary drill bit at a speed between about 250 to 600 rpm and at a thrust of between about 100 to about 10,000 pounds for a time sufficient to drill the hole in the earth strata.
- 16. A cutting insert for a rotary drill bit, the insert comprising:
- one face, an opposite face, and a pair of side surfaces joining said faces;
- said one side surface portion having a leading side relief portion adjacent to the leading face portion and a trailing side relief portion adjacent to the trailing face portion, said leading side relief portion being relieved at an angle so that the interior angle between the one face and the leading side relief portion is less than 90 degrees, said trailing side relief portion having a relief angle that is greater than the relief angle of said leading side relief portion; and
- said leading side relief portion extending from the one face a distance of between about one-third to about two-thirds the thickness of the cutting insert, and said trailing side portion extending from the opposite face a distance of between about one-third to about two-thirds the thickness of the cutting insert.
- 17. The cutting insert of claim 16 wherein said other side surface portion is approximately perpendicular to said leading face portion.
- 18. The cutting insert of claim 16 wherein a layer of polycrystalline diamond covers said one face.
- 19. The cutting insert of claim 16 wherein said one side surface trailing side relief portion has an arcuate shape.
- 20. A roof drill bit comprising:
- a tool body having a cutting insert affixed thereto, said cutting insert having one face, an opposite face, and a side surface joining said one face and said opposite face;
- said side surface having a leading side relief portion adjacent to the one face and a trailing side relief portion adjacent to the opposite face, said trailing side relief portion being of an arcuate shape; and
- said leading side relief portion extending from the one face a distance of between about one-third to about two-thirds the thickness of the cutting insert, and said trailing side relief portion extending from the opposite face a distance of between about one-third to about two-thirds the thickness of the cutting insert.
- 21. The roof drill bit of claim 20 wherein the trailing relief portion is of a convex shape.
- 22. The roof drill bit of claim 20 wherein the trailing relief portion is of a concave shape.
- 23. A cutting insert for a roof drill bit, the insert comprising:
- one face, an opposite face, and a side surface joining said one face and said opposite face;
- said side surface portion having a leading side relief portion adjacent to the one face and a trailing side relief portion adjacent to the opposite face, said trailing side relief portion being of an arcuate shape; and
- said leading side relief portion extending from the one face a distance of between about one-third to about two-thirds the thickness of the cutting insert, and said trailing side portion extending from the opposite face a distance of between about one-third to about two-thirds the thickness of the cutting insert.
- 24. The cutting insert of claim 23 wherein the trailing relief portion is of a convex shape.
- 25. The cutting insert of claim 23 wherein the trailing relief portion is of a concave shape.
- 26. An excavating tool comprising:
- a tool body having a cutting insert affixed to the axially forward end thereof;
- said cutting insert having one face, an opposite face, and a pair of side surfaces joining said faces;
- each one of said side surface portions having a leading side relief portion and a trailing side relief portion, said trailing side relief portion being of an arcuate shape; and
- said leading side relief portion extending from the one face a distance of between about one-third to about two-thirds the thickness of the cutting insert, and said trailing side portion extending from the opposite face a distance of between about one-third to about two-thirds the thickness of the cutting insert.
- 27. The excavating tool of claim 26 wherein the trailing relief portion is of a convex shape.
- 28. The excavating tool of claim 27 wherein said convex trailing relief portion is defined by a constant radius.
- 29. The excavating tool of claim 26 wherein the trailing relief portion is of a concave shape.
- 30. The excavating tool of claim 29 wherein the concave trailing relief portion is defined by a constant radius.
Parent Case Info
This is a continuation of application Ser. No. 08/115,381 filed on Sep. 1, 1995, now abandoned.
US Referenced Citations (19)
Foreign Referenced Citations (2)
Number |
Date |
Country |
516813 |
Sep 1976 |
SUX |
1087649 |
Apr 1984 |
SUX |
Non-Patent Literature Citations (1)
Entry |
Fairhurst, "The Design of Rotary Drilling Bits" (undated). |
Continuations (1)
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Number |
Date |
Country |
Parent |
115381 |
Sep 1993 |
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