US3970158A
Expired / Lapsed
US
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Tooth loading for earth boring bits
Assignee: Hughes Tool Co
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Filing: 1975-04-28
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Granted: 1976-07-20
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Expires: 1995-04-28
Abstract
Abstract Deformable pads are inserted under the hard metal inserts used to form the earth removing teeth of an earth boring bit. The inserts are typically formed of sintered tungsten carbide, with a cylindrical body beveled at the lower end to facilitate insertion into an interferringly sized drilled hole. The volume of the deformable pad or plate is greater than the remaining voids between the hole, the plate and the assembled insert upon initial assembly. Repetitive loading of the insert during drilling deforms the plate to fill said space to evenly distribute stress between the insert and the wall of its retaining hole. A radius between the corner of the wall and bottom of the hole minimizes stress at this corner.
Inventors
- 👤 Bill Adby Black
- 👤 Johannes Gerardus Leon Eenink
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:43
CPC Classifications
E; E21; E21B; E21B10/00; E21B10/46; E21B10/56; E21B10/50; E21B10/52; F; F16; F16B; F16B2200/00; F16B2200/10
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
108 words
An improved earth boring bit comprising a metal body, teeth formed of hard metal inserts secured interferringly in a circular row or drilled holes in the body to engage the bottom of a borehole, a deformable pad under said inserts and in contact with said inserts and the mating associated interferring holes, the volume of the pad being greater than the remaining voids between the hole, the pad, and assembled insert upon initial assembly, and the hardness of the pad being less than that of the metal defining said holes, whereby the pad during drilling and repetitive loading fills said voids between the insert, the pad, and hole.
Claim 2
Dependent Claim
108 words
An improved earth boring bit comprising a metal body, teeth formed of hard metal inserts secured interferringly in a circular row or drilled holes in the body to engage the bottom of a borehole, a deformable pad under said inserts and in contact with said inserts and the mating associated interferring holes, the volume of the pad being greater than the remaining voids between the hole, the pad, and assembled insert upon initial assembly, and the hardness of the pad being less than that of the metal defining said holes, whereby the pad during drilling and repetitive loading fills said voids between the insert, the pad, and hole.
Claim 3
Dependent Claim
78 words
An improved earth boring bit comprising a body, teeth formed of hard metal inserts, some of which are secured interferringly in a circular row of drilled holes having a radius between wall and bottom, a deformable pad under at least the inserts of said circular row, there being a bevel on the lower end of each insert of said circular row, with the volume between the hole and the assembled insert being filled by the pad upon loading.
Claim 4
Dependent Claim
78 words
An improved earth boring bit comprising a body, teeth formed of hard metal inserts, some of which are secured interferringly in a circular row of drilled holes having a radius between wall and bottom, a deformable pad under at least the inserts of said circular row, there being a bevel on the lower end of each insert of said circular row, with the volume between the hole and the assembled insert being filled by the pad upon loading.
Claim 5
Dependent Claim
125 words
In an earth boring bit comprising a steel body and tungsten carbide inserts secured in drilled holes to form earth cutting teeth, one end of each insert being beveled to assist insertion into a drilled hole and the other end shaped in the form of a tooth to remove earth from the bottom of a borehole, the improvement which comprises a deformable pad under each said insert and in contact with said insert and its mating interferring hole, the hole having a radius between its bottom and sidewall, the volume of the pad being greater than the remaining voids between the hole, the pad, and the assembled insert upon initial asembly whereby upon repetitive loading of the insert during drilling the pad fills said voids.
Claim 6
Dependent Claim
125 words
In an earth boring bit comprising a steel body and tungsten carbide inserts secured in drilled holes to form earth cutting teeth, one end of each insert being beveled to assist insertion into a drilled hole and the other end shaped in the form of a tooth to remove earth from the bottom of a borehole, the improvement which comprises a deformable pad under each said insert and in contact with said insert and its mating interferring hole, the hole having a radius between its bottom and sidewall, the volume of the pad being greater than the remaining voids between the hole, the pad, and the assembled insert upon initial asembly whereby upon repetitive loading of the insert during drilling the pad fills said voids.
Claim 7
Dependent Claim
14 words
The invention defined by claim 3 wherein said pad is constructed of mild steel.
Claim 8
Dependent Claim
144 words
An improved rotary-percussive earth boring bit comprising a metal body, inserts retained by interference-fit in said body in mating holes, some of which form a circular row defining a heel row of inserts which are shaped at one end to assist insertion into said holes and shaped at the other end to define earth removing teeth, a deformable pad under at least said heel row inserts and in contact with said heel row inserts and their interferring holes, each hole having a radius between its bottom and sidewall, the volume of each pad being greater than the remaining voids between the hole, the pad, and the assembled insert upon initial assembly, and the hardness of the pad being less than that of the metal defining said hole such that upon loading the pad fills said voids between the insert, the pad, and the hole.
Claim 9
Dependent Claim
144 words
An improved rotary-percussive earth boring bit comprising a metal body, inserts retained by interference-fit in said body in mating holes, some of which form a circular row defining a heel row of inserts which are shaped at one end to assist insertion into said holes and shaped at the other end to define earth removing teeth, a deformable pad under at least said heel row inserts and in contact with said heel row inserts and their interferring holes, each hole having a radius between its bottom and sidewall, the volume of each pad being greater than the remaining voids between the hole, the pad, and the assembled insert upon initial assembly, and the hardness of the pad being less than that of the metal defining said hole such that upon loading the pad fills said voids between the insert, the pad, and the hole.
Claim 10
Dependent Claim
12 words
The invention defined by claim 5 wherein said pad is mild steel.
Claim 11
Dependent Claim
141 words
An improved rotary cutter earth boring bit comprising at least one rotatable cutter body, inserts retained by interference-fit in said cutter body in mating holes to define earth removing teeth, some of which form a circular row defining a heel row of inserts which are shaped at one end to assist insertion into said holes, a deformable pad under at least said heel row inserts and in contact with said heel row inserts and their interferring holes, which each hole having a radius between its bottom and sidewall, the volume of the pad being greater than the remaining voids between the hole, the pad, and the assembled insert upon initial assembly, and the malleability of the pad being such that upon loading the pad fills said voids between the insert, the pad, and the hole without damage to cutter or insert.
Claim 12
Dependent Claim
141 words
An improved rotary cutter earth boring bit comprising at least one rotatable cutter body, inserts retained by interference-fit in said cutter body in mating holes to define earth removing teeth, some of which form a circular row defining a heel row of inserts which are shaped at one end to assist insertion into said holes, a deformable pad under at least said heel row inserts and in contact with said heel row inserts and their interferring holes, which each hole having a radius between its bottom and sidewall, the volume of the pad being greater than the remaining voids between the hole, the pad, and the assembled insert upon initial assembly, and the malleability of the pad being such that upon loading the pad fills said voids between the insert, the pad, and the hole without damage to cutter or insert.
Claim 13
Dependent Claim
12 words
The invention defined by claim 7 wherein said pad is mild steel.
Claim 14
Dependent Claim
131 words
An improved rotary-percussive earth boring bit comprising a hardened steel body, inserts of sintered tungsten carbide retained by interference-fit in said body in mating holes to define earth removing teeth, some of which for a circular row defining a heel row of inserts which are shaped at one end to assist insertion into said holes, a deformable pad under each said heel row insert and in contact with said insert and its interferring hole, which has a radius between its bottom and sidewall, the volume of each pad being greater than the remaining voids between the hole, the pad, and the assembled insert upon initial assembly, and the malleability and hardness of the pad being such that loading fills said voids between the insert, the pad, and hole with said pad.
Claim 15
Dependent Claim
131 words
An improved rotary-percussive earth boring bit comprising a hardened steel body, inserts of sintered tungsten carbide retained by interference-fit in said body in mating holes to define earth removing teeth, some of which for a circular row defining a heel row of inserts which are shaped at one end to assist insertion into said holes, a deformable pad under each said heel row insert and in contact with said insert and its interferring hole, which has a radius between its bottom and sidewall, the volume of each pad being greater than the remaining voids between the hole, the pad, and the assembled insert upon initial assembly, and the malleability and hardness of the pad being such that loading fills said voids between the insert, the pad, and hole with said pad.
Claim 16
Dependent Claim
13 words
The invention defined by claim 9 wherein said pad is circular mild steel.
Claim 17
Dependent Claim
139 words
An improved rotary cutter earth boring bit comprising plural rotatable hardened steel cutter bodies, inserts of sintered tungsten carbide retained by interference-fit in said cutter bodies in mating holes to define earth removing teeth, each cutter having a circular row of inserts defining a heel row, the inserts being shaped at one end to assist insertion into said holes, a deformable pad under at least said heel row inserts in contact with said heel row inserts and their interferring holes, which each have a radius between its bottom and sidewall, the volume of the pad being greater than the remaining voids between the hole, the pad, and the assembled insert upon initial assembly, and the malleability of the pad being such that upon loading the pad fills said voids between insert and hole without damage to cutter or insert.
Claim 18
Dependent Claim
139 words
An improved rotary cutter earth boring bit comprising plural rotatable hardened steel cutter bodies, inserts of sintered tungsten carbide retained by interference-fit in said cutter bodies in mating holes to define earth removing teeth, each cutter having a circular row of inserts defining a heel row, the inserts being shaped at one end to assist insertion into said holes, a deformable pad under at least said heel row inserts in contact with said heel row inserts and their interferring holes, which each have a radius between its bottom and sidewall, the volume of the pad being greater than the remaining voids between the hole, the pad, and the assembled insert upon initial assembly, and the malleability of the pad being such that upon loading the pad fills said voids between insert and hole without damage to cutter or insert.
Claim 19
Dependent Claim
12 words
The invention defined by claim 11 wherein said pad is mild steel.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-07-20 | 1980-01-19 | 1980-07-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-07-20 | 1984-01-19 | 1984-07-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-07-20 | 1988-01-19 | 1988-07-20 | $7700.00 | Window Closed / Lapsed |