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US 4,121,865 AGranted
Pickup method and apparatus
OwnerRobert L. Littwin, Sr.inventor
Life of this patent
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OwnerRobert L. Littwin, Sr.inventor
Estimating the term…
A multipurpose lifting device with variable holding power to both electromagnet and vacuum cup pickup structure to eliminate any physical damage either external or internal to the workpiece by distortion, with a permanent magnet feature to be used as a standby safety, or used in conjunction with the electromagnet and vacuum cup structure to triple the lifting power per square inch of surface area when attached to the workpiece. This structure is a perfected device for picking up a plate or sheet of ferrous or non-ferrous material individually from a stack of same. The power to the unit can be variably controlled to eliminate distortion to the sheet or plate for transport with an independent self-regulating permanent magnet safety for ferrous metal. If all power to the apparatus fails, it will automatically retain the ferrous metal sheet indefinitely until it can be brought to rest in a safe position.
A lifting device for sheet material, comprising a vertically suspended body, a suction cup depending from said body having a fixed sealing surface engageable with said sheet material, flexible means for cushioning engagement of the sealing surface with the sheet material and suction chamber means rendered effective in response to said engagement of the sealing surface for holding the sheet material on the body with a predetermined holding force, a permanent magnet, means mounting the permanent magnet in the body for exerting a magnetic holding force on the sheet material while in contact with the sealing surface and movable mechanical means connected to the permanent magnet for rendering the same ineffective in a standby condition by reducing the magnetic holding force applied to the sheet material.
A lifting device for sheet material, comprising a body, a suction cup fixedly mounted on the body having flexible means engageable with the sheet material for holding the same on the body under a predetermined suction pressure, a permanent magnet having at least one relatively movable section, means mounting said permanent magnet on the body for exerting a magnetic holding force on the sheet material while in engagement with the flexible means of the suction cup, and means connected to the permanent magnet for varying the magnetic holding force applied to the sheet material in response to displacement of the movable section relative to the body.
Dependencies are inferred from the claim text.