Eddy current separation of blanks for the automated destacking of aluminum sheet

Abstract

A method of separating blanks from a stack includes positioning a magnetic field generator in a fixed location proximate a peripheral edge of an upper portion of the stack, activating the magnetic field generator such that eddy currents are generated and result in a force vector in a direction away from a top-most blank of the stack, and pushing a blank, or multiple blanks, immediately below the top-most blank away from the top-most blank by the eddy currents.

What is claimed is: 
     
         1 . A method of separating a blank from a stack of blanks comprising:
 positioning a magnetic field generator in a fixed location proximate a peripheral edge of an upper portion of the stack;   activating the magnetic field generator such that eddy currents are generated and result in a force vector in a direction away from a top-most blank; and   pushing, by the magnetic field generator, at least one blank immediately below the top-most blank away from the top-most blank after the top-most blank is lifted by an external device,   wherein the magnetic field generator is disposed relative to the stack in a way such that the force vector is applied on the at least one blank to separate the at least one blank from the top-most blank before the top-most blank and the at least one blank are completely separated from remaining blanks of the stack.   
     
     
         2 . The method according to  claim 1 , wherein the blanks are an aluminum alloy material. 
     
     
         3 . The method according to  claim 1 , wherein the magnetic field generator is an electromagnet. 
     
     
         4 . The method according to  claim 1 , wherein the magnetic field generator is a rotating assembly of permanent magnets having alternating north and south poles. 
     
     
         5 . The method according to  claim 1  further comprising injecting air into a side of the stack as the individual blanks are separated by the eddy currents. 
     
     
         6 . The method according to  claim 1 , wherein a width of the blanks is between about 25 mm to about 3000 mm, a length of the blanks is between about 25 mm to about 3000 mm, a thickness of each blank is between about 0.5 mm to about 6.0 mm, and a height of the stack of blanks is between about 1 mm to about 2000 mm. 
     
     
         7 . The method according to  claim 1  further comprising a step of moving the top-most blank to a subsequent manufacturing operation. 
     
     
         8 . The method according to  claim 1 , wherein only one sheet at a time is displaced by the magnetic field generator. 
     
     
         9 . The method according to  claim 1 , wherein the gravitational direction is between 90 degrees and 75 degrees as measured from a normal face of a blank. 
     
     
         10 . An apparatus for separating blanks from a stack comprising:
 a fixed magnetic field generator;   a jig configured to hold and translate the stack of blanks past the fixed magnetic generator such that a peripheral edge of an upper portion of the stack is continually positioned proximate the fixed magnetic field generator; and   a position sensor for detecting a position of the jig,   wherein eddy currents from the fixed magnetic field generator force an unwanted blank immediately below a top-most blank of the stack to be separated from the top-most blank of the stack and to fall with gravity after the top-most blank is lifted by an external device, and   wherein the fixed magnetic field generator is disposed relative to the stack in a way such that the eddy currents separate the unwanted blank from the top-most blank before the top-most blank and the unwanted blank are completely separated from remaining blanks of the stack.   
     
     
         11 . The apparatus according to  claim 10 , wherein the magnetic field generator includes a polyphase winding. 
     
     
         12 . The apparatus according to  claim 10 , wherein the magnetic field generator is a rotating assembly of permanent magnets having alternating north and south poles. 
     
     
         13 . The apparatus according to  claim 10  further comprising an air knife configured to inject air into the stack as the unwanted blank is separated by the eddy currents. 
     
     
         14 . The apparatus according to  claim 10  further comprising a transport mechanism configured to move the top-most blank to a subsequent manufacturing operation. 
     
     
         15 . The apparatus according to  claim 14 , wherein the transport mechanism comprises a plurality of suction cups configured to hold the top-most blank of the stack. 
     
     
         16 . The apparatus according to  claim 14 , wherein the transport mechanism comprises a robot with an end effector to hold the stack of blanks. 
     
     
         17 . The apparatus according to  claim 10  further comprising a controller configured to transmit signals to the jig for translational movement. 
     
     
         18 . The apparatus according to  claim 17 , wherein the position sensor is in communication with the controller to transmit the position of the jig to the controller. 
     
     
         19 . The apparatus according to  claim 10 , wherein the stack of blanks is not injected with any current by way of physical contact. 
     
     
         20 . The apparatus according to  claim 10  wherein the eddy currents result in a force vector in a direction between 90 degrees and 75 degrees as measured from a normal face of a blank.