Safety device for power-operated presses and the like
AssigneeThe Positive Safety Manufacturing Company
InventorJohn K. Loeser
Life of this patent
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Abstract
A safety device is provided for the operation of small presses, spot welding machines, etc. The device is characterized by the use of a probe or sensor whose movement, if obstructed, prevents closing of an electrical circuit which activates the punch or ram of the press. Means are provided for minimizing or eliminating bounce or vibration of the sensor to avoid erratic operation of the device and the press. Provision is also made for rendering the device "fail-safe" under certain conditions, including failure of internal parts of the device or improper usage of the device by the operator. Economies in manufacture of the device are effected by the improvement of certain parts and elimination of other parts of previously used devices of a similar nature and construction.
Claims6
In a safety device of the character described, a housing, a probe shaft mounted in said housing for vertical reciprocal sliding movement, a sensor or probe supported by said probe shaft, a solenoid mounted on said housing and having an armature movable along an axis parallel with said probe shaft, a beam mounted for pivotal movement in said housing, and operatively connected at one end with said probe shaft, said beam movable in response to energization of said armature to permit said probe shaft and sensor or probe to fall by gravity, spring-actuated means operative in opposition to said armature for moving said beam to cause said probe shaft to be moved to a raised inoperative position, and means including an electrical circuit for controlling operation of a press or machine in response to said gravity fall, said circuit including a limit switch having a switch closing arm provided with a roller, and a switch actuator arm supported by said probe shaft and having a terminal inclined portion adapted to engage said roller, and to have a combined rolling and wedging engagement with the roller during said gravity fall, whereby bounce or vibration of the probe shaft and sensor is eliminated and positive operation of the limit switch and probe or sensor is assured.
Dependencies are inferred from the claim text.