(19) |
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(11) |
EP 0 452 999 A3 |
(12) |
EUROPEAN PATENT APPLICATION |
(88) |
Date of publication A3: |
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11.03.1992 Bulletin 1992/11 |
(43) |
Date of publication A2: |
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23.10.1991 Bulletin 1991/43 |
(22) |
Date of filing: 10.09.1987 |
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(84) |
Designated Contracting States: |
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BE DE FR GB NL |
(30) |
Priority: |
11.09.1986 US 906169
|
(62) |
Application number of the earlier application in accordance with Art. 76 EPC: |
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87113231.2 / 0259872 |
(71) |
Applicant: Eastman Teleco Company |
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Houston, Texas 77032-1925 (US) |
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(72) |
Inventor: |
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- Trujillo, William R.
West Jordan,
Utah 84084 (US)
|
(74) |
Representative: Busse & Busse
Patentanwälte |
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Postfach 12 26 49002 Osnabrück 49002 Osnabrück (DE) |
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|
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Remarks: |
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This application was filed on 12 - 07 - 1991 as a divisional application to the application
mentioned under INID code 60. |
|
(54) |
A rotating bit with junk slots in its gage |
(57) An improved rotating drag bit for cutting plastic, sticky, water reactive and shale
formations is devised by providing a plurality of large diamond cutters having a circular
cutting face in excess of a three quarter inch in diameter. Each large cutter is provided
with at least one hydraulic nozzle which in turn provides a directed hydraulic flow
at the corresponding cutter face. The directed hydraulic flow is positioned to apply
a force to the chip which tends to peel the chip away frog the cutter face. In addition,
the hydraulic flow is positioned with respect to the chip so as to apply an off-center
torque to the chip which is used to peel the chip away from the cutter face and toward
the gage of the bit. In particular, the nozzle defines a jet which is characterized
by a direction and velocity of hydraulic fluid determined by the jet characteristics.
The core is generally symmetric about its longitudinal axis and has a length along
the longitudinal axis and width perpendicular thereto. The point of the jet most distant
from the nozzle defines an impact point of the jet against the chip and cutter face.
The longitudinal axis of the jet is chosen so that at least a portion of the jet axis
lies between the cutter face and the chip as it is being peeled from the cutter. Hydraulic
removal of the chips is further facilitated by a plurality of junk slots having a
contained compound surface. The jug slot is characterized by having at least two distinct
cross-sectional profiles, namely an asymmetric profile at its lower portion nearest
the bit face and a symmetric profile along its upper portion. The asymmetric and symmetric
profiles are connected by a surface providing a smooth hydrodynamic transition.
