Drill bit

Claim 2

A roller cutter, comprising a body, at least one substantially chisel-shaped circumferential web on said body, and a plurality of hardened, wear-resistant cylindrical inserts, said inserts having a chisel-shaped end and being positioned in recesses defined in said web and extending into said body with their chisel-shaped end being in substantial alignment and conformity with the chisel-shape of said web to provide a substantially continuous formation engaging crest, the recesses defiNed in said web and body being of a size in relation to said inserts to support said inserts by engagement with substantially the entire cylindrical surfaces of said inserts.

Claim 3

A roller cutter, comprising a body, at least one web extending circumferentially around said body, and a plurality of hardened, wear-resistant generally cylindrically shaped inserts, said inserts having a formation engaging end with a chisel-shape defined by two outwardly converging faces, the cylindrical surface of said inserts at each side of said faces extending substantially to the formation engaging crests of said inserts, said inserts being mounted in recesses in said web with the web in supporting relationship to substantially all of the cylindrical surfaces of said inserts at the sides of said faces, said web being chisel-shaped in section and the crest of said web and the crests of said inserts defining a substantially continuous formation engaging crest around said body.

Claim 4

A roller cutter, comprising a body, at least one web extending circumferentially around said body, and a plurality of hardened, wear-resistant generally cylindrically shaped inserts, said inserts having a formation engaging end with a chisel-shape defined by two outwardly converging faces, the cylindrical surface of said inserts at each side of said faces extending substantially to the formation engaging crests of said inserts, said inserts being mounted in recesses in said web with the web in supporting relationship to substantially all of the cylindrical surfaces of said inserts at the sides of said faces, said web being chisel-shaped in section and the crest of said web and the crests of said inserts defining a substantially continuous formation engaging crest around said body.

Claim 5

A drill bit, comprising a head, a plurality of roller cutters rotatably mounted on said head, at least one of said roller cutters having a body, at least one substantially chisel-shaped circumferential web on said body, and a plurality of hardened, wear-resistant, cylindrical inserts, one end of which is chisel-shaped, each of said inserts being secured in said web with said web being in supporting engagement with substantially all of the cylindrical surfaces of said inserts, and the crests of said web and said inserts defining a substantially continuous formation engaging crest around said body.

Claim 6

A drill bit, comprising a head, a plurality of roller cutters rotatably mounted on said head, at least one of said roller cutters having a body, at least one substantially chisel-shaped circumferential web on said body, and a plurality of hardened, wear-resistant, cylindrical inserts, one end of which is chisel-shaped, each of said inserts being secured in said web with said web being in supporting engagement with substantially all of the cylindrical surfaces of said inserts, and the crests of said web and said inserts defining a substantially continuous formation engaging crest around said body.

Claim 7

A roller cutter, comprising a body, at least one web extending circumferentially around said body, and a plurality of hardened, wear-resistant generally cylindrically shaped inserts, said inserts having a formation engaging end with a chisel-shape defined by two outwardly converging faces, the cylindrical surface of said inserts at each side of said faces extending substantially to the formation engaging crests of said inserts, said inserts being mounted in recesses in said web with the web in supporting relationship to substantially all of the cylindrical surfaces of said inserts at the sides of said faces, the crest of said inserts being in substantial alignment with the circumferential crest defined by said web.

Claim 8

A roller cutter, comprising a body, at least one web extending circumferentially around said body, and a plurality of hardened, wear-resistant generally cylindrically shaped inserts, said inserts having a formation engaging end with a chisel-shape defined by two outwardly converging faces, the cylindrical surface of said inserts at each side of said faces extending substantially to the formation engaging crests of said inserts, said inserts being mounted in recesses in said web with the web in supporting relationship to substantially all of the cylindrical surfaces of said inserts at the sides of said faces, the crest of said inserts being in substantial alignment with the circumferential crest defined by said web.

Claim 9

A roller cutter according to claim 4, wherein said recesses extend through said web and substantially into said body.

Claim 10

A drill bit according to claim 4, wherein said body and said web are steel and all of said body and said web is carburized except the fillet existing between said body and said web, and said inserts are tungsten carbide.

Claim 11

A roller cutter, comprising a body, at least one substantially chisel-shaped circumferential web on said body, and a plurality of hardened, wear-resistant, cylindrical inserts, one end of which is chisel-shaped, each of said inserts being secured in said web with said web being in supporting engagement with a substantial portion of the cylindrical surfaces of the chisel portion of said inserts, the crest of said inserts being in substantial alignment with the circumferential crest defined by said web.

Claim 12

A roller cutter, comprising a body, at least one substantially chisel-shaped circumferential web on said body, and a plurality of hardened, wear-resistant, cylindrical inserts, one end of which is chisel-shaped, each of said inserts being secured in said web with said web being in supporting engagement with a substantial portion of the cylindrical surfaces of the chisel portion of said inserts, the crest of said inserts being in substantial alignment with the circumferential crest defined by said web.

Claim 13

A roller cutter, comprising a body, at least one web extending circumferentially around said body, a plurality of hardened, wear-resistant generally cylindrically shaped inserts, said inserts having a chisel-shaped end and being positioned in recesses defined in said web and extending into said body, the sectional shape and size of the chisel portion of said insert being substantially the same as the sectional shape and size of said web, the recesses defined in said web and body being of a size in relation to said inserts to support said inserts by engagement with substantially the entire cylindrical surfaces of said inserts, said supporting engagement of said web extending to a substantial portion of the cylindrical Surfaces on the chisel portion of said insert to provide such mutual supporting relationship between said inserts and said web, the crest of said inserts being in substantial alignment with the tract of the crest of said web.

Claim 14

A roller cutter, comprising a body, at least one web extending circumferentially around said body, a plurality of hardened, wear-resistant generally cylindrically shaped inserts, said inserts having a chisel-shaped end and being positioned in recesses defined in said web and extending into said body, the sectional shape and size of the chisel portion of said insert being substantially the same as the sectional shape and size of said web, the recesses defined in said web and body being of a size in relation to said inserts to support said inserts by engagement with substantially the entire cylindrical surfaces of said inserts, said supporting engagement of said web extending to a substantial portion of the cylindrical Surfaces on the chisel portion of said insert to provide such mutual supporting relationship between said inserts and said web, the crest of said inserts being in substantial alignment with the tract of the crest of said web.

Claim 15

A drill bit, comprising a head, a plurality of roller cutters rotatably mounted on said head, at least one of said roller cutters having a body, at least one circumferential web on said body, and a plurality of hardened, wear-resistant, cylindrical inserts, one end of which is chisel-shaped, each of said inserts being secured in said web with said web being in supporting engagement with substantially all of the cylindrical surfaces of said inserts which lie along the axial length of the chisel portion of said inserts, the crest of said inserts being in substantial alignment with the circumferential crest defined by said web.

Claim 16

A drill bit, comprising a head, a plurality of roller cutters rotatably mounted on said head, at least one of said roller cutters having a body, at least one circumferential web on said body, and a plurality of hardened, wear-resistant, cylindrical inserts, one end of which is chisel-shaped, each of said inserts being secured in said web with said web being in supporting engagement with substantially all of the cylindrical surfaces of said inserts which lie along the axial length of the chisel portion of said inserts, the crest of said inserts being in substantial alignment with the circumferential crest defined by said web.

Claim 17

A drill bit roller cutter, comprising a body, at least one row of cutting elements on said body comprising, substantially chisel-shaped spaced steel teeth having circumferentially extending crests, cylindrical wear-resistant inserts mounted in said row between said steel teeth, said teeth being in engagement to a sufficient portion of the cylindrical surfaces on said inserts to provide mutual support for said teeth and said inserts to assure a long useful life thereof, said wear-resistant inserts having circumferentially extending cutting crests forming a substantially continuous formation engaging crest with the crests of said steel teeth.

Claim 18

A drill bit roller cutter, comprising a body, at least one row of cutting elements on said body comprising, substantially chisel-shaped spaced steel teeth having circumferentially extending crests, cylindrical wear-resistant inserts mounted in said row between said steel teeth, said teeth being in engagement to a sufficient portion of the cylindrical surfaces on said inserts to provide mutual support for said teeth and said inserts to assure a long useful life thereof, said wear-resistant inserts having circumferentially extending cutting crests forming a substantially continuous formation engaging crest with the crests of said steel teeth.