Patent US3842942A successfully refreshed from Google Patents.
US3842942A
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US
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Constrained layer damper and noise suppressor for a rock drill steel
Assignee: United States Department of the Interior
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Filing: 1973-10-01
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Granted: 1974-10-22
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Expires: 1993-10-01
Abstract
Abstract A constrained layer damper and noise suppressor which is made an integral part of a rock drill steel shaft. Rearward of the drill bit a viscoelastic layer constituting a damping medium is bonded around the drill steel for a major portion of its length. Coextensive with the outer diameter of this medium a smooth thin walled rigid abrasive resistant tube is bonded. Usually the diameter of the constraint tube is less than the major diameter of the drill bit so the entire invention can penetrate a drilled hole.
Inventors
- 👤 J Jensen
- 👤 A Visnapuu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:54
CPC Classifications
E; E21; E21B; E21B17/00; B; B25; B25D; B25D17/00; B25D17/11; E21B1/00; E21B1/38; Y; Y10; Y10S; Y10S173/00; Y10S173/02
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
95 words
A combined constrained layer damper and noise suppressor for a rock drill steel shaft comprising: an elongated drill steel shaft; a drill bit rigidly fixed at the front end oF said shaft; a viscoelastic layer damping medium bonded around said steel shaft rearward of the drill bit and extending substantially along its entire length; and a smooth, rigid constraint tube bonded to the outer surface of said medium and coextensive therewith along substantially its entire length, said tube having a wall thickness much less than said medium and less than one tenth its outer diameter.
Claim 2
Dependent Claim
95 words
A combined constrained layer damper and noise suppressor for a rock drill steel shaft comprising: an elongated drill steel shaft; a drill bit rigidly fixed at the front end oF said shaft; a viscoelastic layer damping medium bonded around said steel shaft rearward of the drill bit and extending substantially along its entire length; and a smooth, rigid constraint tube bonded to the outer surface of said medium and coextensive therewith along substantially its entire length, said tube having a wall thickness much less than said medium and less than one tenth its outer diameter.
Claim 3
Dependent Claim
18 words
The apparatus of claim 1 wherein said tube is made of a thin walled abrasive resistant metal material.
Claim 4
Dependent Claim
31 words
The apparatus of claim 1 wherein said drill bit has a cross section surface dimension such that it is greater in diameter than the cross sectional diameter of said constraint tube.
Claim 5
Dependent Claim
21 words
The apparatus of claim 1 wherein there are exposed areas of the damping medium at either end of the constraint tube.
Claim 6
Dependent Claim
23 words
The apparatus of claim 2 wherein said viscoelastic layer comprises a butyl rubber composition and said metal tube is made of carbon steel.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-21 | 1978-04-22 | 1978-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-21 | 1982-04-22 | 1982-10-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-21 | 1986-04-22 | 1986-10-22 | $7700.00 | Window Closed / Lapsed |