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US 5,295,770 AGranted
Air feed peck drill with pneumatic safety system
AssigneeIndresco Inc.
InventorsRobert A. Pennison, Richard E. Eckman
Life of this patent
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AssigneeIndresco Inc.
InventorsRobert A. Pennison, Richard E. Eckman
Estimating the term…
A pneumatic air feed peck drill adapted to drill in repetitive cycles including a rapid advance phase, a slower drilling phase, and a rapid retract phase. The rapid advance phase ends and the drilling phase begins at a set back position, an adjustable distance from the workpiece, to minimize a drill bit and workpiece damage. The drill includes a drill motor and feed cylinder powered by air to rotate and advance and retract the drill motor. The drill motor and feed cylinder is coupled with an air and mechanical control system including a hydraulic feed control unit having a piston rod coupled with the drill motor to dampen the advance of the drill motor during the drilling phase and to release for rapid retract and advance phases. A brake is mounted for control of the feed control unit piston rod to releasably engage the piston rod during the retract phase to limit the movement of the rod to an adjustable set back distance controlled by a set back nut limiting the distance the brake may move relative to the feed control unit when the brake engages the piston rod. A pneumatic system including a volume chamber is coupled with the air system to control the peck cycle rate. One embodiment of the drill includes an auxiliary thrust and retract piston assembly while another embodiment has only the primary drill motor and feed cylinder. A further embodiment includes an interrupt valve in the pneumatic system to disable the drill when a safety shield is removed. The safety shield may be transparent plastic with incremental markings to aid in making adjustments.
A pneumatic peck drill operable in repetitive cycles including a rapid advance phase to a set back distance from a workpiece, a drilling phase, and a retract phase, comprising:
A pneumatic peck drill operable in repetitive peck cycles including a rapid advance phase, a drilling phase, and a retract phase comprising:
In a pneumatic peck drill having a drill motor and feed cylinder assembly, a yoke secured with the drill motor for advancing and retracing said drill motor, a thrust arm connected with a yoke, a hydraulic feed control unit mounted for operation with the thrust arm for controlling movement of the thrust arm, and apparatus for controlling a rapid advance phase, drilling phase, and a retract phase of said peck drill including a pneumatic master valve, and a safety shroud covering exposed movable parts of said peck drill, the improvement comprising a safety system to disable said peck drill when said shroud is removed including an interrupt valve in an air supply line to said master valve, said interrupt valve being engageable by said shroud to hold said interrupt closed when said shroud is in operating position on said peck drill, and means biasing said interrupt valve toward an open position for opening said interrupt valve upon removal of said shroud from said peck drill.
Dependencies are inferred from the claim text.