Automatic fault detection system for a machine tool
First Claim
1. A fault detection system for use with a machine and operable through a cycle of operation upon receipt of a start check signal from the machine;
- comprising a combination pneumatic-mechanical cylinder limit valve forming a sensor which includes a movable rod provided with a spool portion;
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Accused Products
Abstract
An automatic fault detection system for use with machine tools to detect the breakage or absence of the tool, the presence and/or absence of a portion of the workpiece, and to prevent the normal cycle of operation of the machine when such condition exists, includes a sensor having a rod, a power port and a pair of pressure sensing ports. First and second pressure sensing switches are connected to the sensing ports wherein the failure of the sensor rod to fully retract or to advance before or beyond good check stroke position respectively exhausts the pressure sensing switches preventing operation of the machine cycle.
24 Citations
9 Claims
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1. A fault detection system for use with a machine and operable through a cycle of operation upon receipt of a start check signal from the machine;
comprising a combination pneumatic-mechanical cylinder limit valve forming a sensor which includes a movable rod provided with a spool portion; - View Dependent Claims (3, 4, 5, 6, 7, 8, 9)
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2. said sensor further including a power port and first and second pressure sensing ports;
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means biasing said rod to an extended position into engagement with a target such as a tool or a workpiece, the presence of which is necessary for proper operation of the machine; a control unit including a source of air under pressure; first means operable upon supplying air under pressure to said control unit which then allows air to reach said first pressure sensing port and said power port to move said rod towards a retracted position; said first pressure sensing port being normally vented to atmosphere but blocked by said spool portion and rod when said rod is fully retracted; a first pressure sensing switch responsive to and actuated by a pressure build up at said first pressure sensing port when said rod is fully retracted; second means connected to said first means and effective when energized by receipt of the start check signal after said first pressure sensing switch is actuated to shift said first means to thereby block the flow of air to said power port and to said first pressure sensing port, and successively supply air under pressure to said second pressure sensing port; means venting said second pressure sensing port to atmosphere except when said rod is extended by its biasing means and thereby moved to a good check stroke position engaging the target and blocking said second pressure sensing port; and a second pressure sensing switch responsive to and actuated by a build up of pressure at said second pressure sensing port due to said blockage to activate the machine for a cycle of operation.
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Specification