Cutting by use of rotating axially moving tool – With work-infeed means
Reexamination Certificate
1998-12-23
2001-01-30
Howell, Daniel W. (Department: 3722)
Cutting by use of rotating axially moving tool
With work-infeed means
C408S104000, C082S131000
Reexamination Certificate
active
06179529
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a centering and drilling method and machine, in which the drill bit and the component to be bored rotate in opposite directions. The present invention allows an exact concentric passage to be drilled that has greater accuracy than prior art techniques.
2. Background Art
With prior art devices, the drilled bore is not perfectly concentric, particularly for longer components. A minute offset or angle existing between the centerline of the drill and the centerline of the component at the starting position will result in the center of the passage not being co-linear with the centerline of the component along the length thereof. Such variation or offset in the position of the passage is undesired, particularly in components requiring exacting tolerances.
Prior art methods traditionally encompass a system in which the component is stationarily positioned and the drill bit rotates. The rotating drill bit is then moved toward and longitudinally through the component to bore a passage therein. Since minute offsets between the axis of the drill bit and the longitudinal axis of the component cause the passage to be non-concentric, many attempts have been made in the prior art to overcome this problem. One approach is using guides for the drill or component, which is disclosed for example in U.S. Pat. Nos. 3,371,560 to K{umlaut over (a)}ser, 4,470,116 to Wellach, and 1,376,791 to Baker et al. Furthermore, U.S. Pat. Nos. 3,674,375, 2,330,577, 800,599, 1,529,557, 787,893, and 766,748 relate generally to work holders and centering devices.
U.S. Pat. No. Re 24,289 to Farnsworth discloses a different drilling device, in which the component is rotated about its longitudinal axis and the drill bit is stationary. However, these disclosed prior art techniques fail to bore a perfectly concentric passage in the component consistently, particularly for longer components. A problem is that the operator's ability to align exactly the axis of the drill bit with the longitudinal axis of the component is limited.
Therefore, a need exists in the art for a system that consistently allows concentric passages to be bored through a component. The system should be self-correcting so that a very slight misalignment by the operator is continually corrected as the system bores the passage. It is also desired that the system be inexpensive and easy to use.
SUMMARY OF THE INVENTION
The present invention, which comprises an apparatus and method for drilling an exactly concentric passage through a component, satisfies the above-discussed needs in the art. The component is rotated about its longitudinal axis, which is disposed along a centerline of the apparatus. In conjunction, the drill bit turns (or rotates) about its axis of rotation, which is also oriented along and co-linearly with the centerline of the apparatus. The drill bit, however, turns in the opposite direction as the component is rotated. The turning drill bit and rotating component are moved longitudinally toward each other so that the drill bit bores through component substantially along its longitudinal axis to form a passage therein.
The counter-rotational motion between the drill bit and the component moves the drill bit or component toward the centerline of the apparatus on every rotation as a result of centripetal force. That is, the opposed rotation of the drill bit and component acts to position the drill bit at the longitudinal axis of the component, thereby self-centering the drill bit.
Other aspects of the present invention include a variable speed motor controller that maintains constant torque between the component and the drill bit for optimum surface footage control. In addition, gundrill alignment bushings rotate with the component, which maintains an oil seal between the component and the drill bushing, further improving concentricity of the passage.
REFERENCES:
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McClure Richard
McClure Robert
Howell Daniel W.
Needle & Rosenberg P.C.
UFF Machine Company
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