Cutting by use of rotating axially moving tool – Processes – Bit detachable
Reexamination Certificate
2000-03-15
2002-04-09
Howell, Daniel W. (Department: 3722)
Cutting by use of rotating axially moving tool
Processes
Bit detachable
C408S014000, C408S130000, C408S24100G
Reexamination Certificate
active
06368031
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to drilling apparatuses and, more particularly, to an axial feed apparatus having an adjustable feed stop and associated method.
BACKGROUND OF THE INVENTION
The production of components of an assembly, for example, airplane structural components, often requires that holes be drilled in the components to accommodate the fasteners that secure the assembly together. In some instances, the drilled holes may also need to be countersunk. Typically, the countersink has a preferred depth where the diameter of the countersink is matched to the fastener being used. If the countersink is not deep enough, the fastener may protrude outwardly of the component surface. If the countersink is too deep, particularly in a thin-section component, the hole associated with the countersink may be unacceptably large, the structural strength of the component may be adversely affected, and the fastener may not be able to securely fasten the component. In addition, the excess countersink depth, after the fastener has been installed, will define a cavity which may undesirably collect debris or disrupt airflow about the component. Further, since these components are generally fabricated in a manufacturing operation, where multiple holes must be drilled and countersunk in one or more components, consistency of the countersink depth is also typically required. In some instances, it is also desirable that a drill/countersink operation be performed in a single pass of the drilling/countersinking device in order to reduce the time and additional costs associated with rework or multi-pass procedures.
Drilling and countersinking are related processes which may be accomplished using two or more separate cutters or a single cutter capable of performing both functions. However, the countersinking operation is often the most sensitive to the depth of the cut than the drilling operation. Thus, the term “countersinking” will be used herein for the sake of simplicity, but it is understood that any description of a countersinking operation is equally applicable to a drilling operation.
In some manufacturing operations, countersinking processes are manually performed using a handheld drill motor. Where the operation includes a countersinking process, a mechanism for controlling the depth of the countersink may be secured in the chuck of the drill motor, to the drill motor, or to the cutter itself. However, a manual countersinking operation may be unacceptable for some manufacturing operations due to inconsistency caused by the operator(s). In addition, the depth control mechanism may require frequent adjustments to maintain a consistent countersink, particularly in the event that, for example, the cutter is changed or adjusted or a different drill motor is used for the process. Thus, there exists a need for a countersinking device capable of operating automatically with minimal operator involvement. In addition, there exists a need for a device capable of consistently, accurately and repeatably controlling the depth of a countersink. Such a device should require minimal adjustments to obtain and/or maintain the desired countersink depth, even if the cutter is changed or a different drill motor is used for the operation.
In some situations, countersinking processes may be performed with, for example, pneumatic power feed equipment, wherein a pneumatic drill motor is used to turn a cutter while an integral feed mechanism feeds and retracts the cutter over a predetermined distance. The relative positioning of the component or workpiece with respect to the travel of the cutter generally determines the depth of the countersink. In practice, the depth of the countersink may be controlled by a mechanism interacting with the chuck, the cutter, and/or the drill motor. However, such a device, much like the manual drill motor previously described, may require frequent adjustments to maintain a consistent countersink, particularly in the event that, for example, the cutter is changed or adjusted or a different drill motor is used for the process. In some instances, adjusting the device may be a complicated procedure requiring at least partial disassembly of the countersinking apparatus.
Alternatively, a dead stop may be used in conjunction with the feed mechanism, wherein the dead stop stops the feed mechanism, and thus the cutter, at a predetermined limit. However, the feed mechanism may not necessarily be aligned with or securely fixed to the drill motor, thereby possibly causing unacceptable deviations from the desired countersink depth since the feed mechanism may not be able to sense and/or respond to the actual forces experienced by the cutter. Further, the feed mechanism may form an integral assembly with the drill motor, thereby limiting the applicability of depth control mechanism if, for example, a different drill motor must be used for the operation due to size or accessibility constraints in the countersinking process. Thus, there exists a further need for a device capable of consistently, accurately and repeatably controlling the depth of a countersink cutter that is driven by a drill motor and fed by pneumatic power feed equipment. Such a device should be in communication with the cutter such that the position of the cutter and/or the forces experienced by the cutter can be included in the determination of the desired countersink depth. The device should also be able to obtain and/or maintain the desired countersink depth if the cutter is changed or a different drill motor is used for the operation and preferably accomplishes this consistency without requiring excessive and/or complicated adjustments.
Thus, there exists a need for pneumatic power feed equipment, particularly equipment used in countersinking processes in a manufacturing operation, having a device capable of consistently, accurately and repeatably controlling the depth of the countersink. Such a device should also be able to obtain and/or maintain the desired countersink depth, even if the cutter is changed or a different drill motor is used for the operation, and preferably accomplishes this consistency without requiring excessive and/or complicated adjustment. The device should also be in communication with the cutter such that the position of the cutter and/or the forces experienced by the cutter can be included in the determination of the desired countersink depth.
SUMMARY OF THE INVENTION
The above and other needs are met by the present invention which, in one embodiment, provides an axial feed apparatus having an adjustable feed stop. The apparatus generally comprises a hydraulically-actuated device, a sleeve, a spindle, and a collar. The hydraulically-actuated device comprises a feed member slidably disposed within a housing. The sleeve has a first end engaging the housing and a second end extending outwardly therefrom, wherein the second end defines a series of graduations thereabout. The spindle has a feed stop extending into the housing through the sleeve such that the feed stop is capable of engaging the feed member and providing a feed limit. The collar surrounds the spindle outwardly of the housing and is rotationally fixed with respect to the spindle. The collar further defines a series of graduations thereabout corresponding to, and engageable with, the sleeve graduations. The spindle is thereby prevented from rotating when the collar graduations engage the sleeve graduations. The collar is firther slidably engaged with the spindle to allow disengagement of the graduations and rotation of the spindle. Preferably, the graduations and the spindle are configured such that a rotational change of the collar graduations with respect to the sleeve graduations moves the feed stop by a corresponding axial distance.
In some instances, the hydraulically-actuated device comprises a pneumatic drill motor having a power feed module and, in other instances, a hydraulic power feed module. The apparatus may further comprise a mechanical bias member operably connected between the spindle and the collar i
Blankenship Thomas O.
Fritsche David L.
King Daniel C.
Martinek Brian J.
Morrison James L.
Howell Daniel W.
The Boeing Company
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