Abstract:
The invention is a magnet for facilitating separation of individual sheets from a stack of ferro-magnetic sheets; the invention is in the form of an elongate housing containing an elongate array of magnets which may be selectively positioned in relation to the housing so as to bring the array in proximity to the edge of the stack of ferro-magnetic sheets, thereby inducing a magnetic field in said sheets and causing the sheets to separate, thereby facilitating manipulation of the uppermost sheet from the stack.

Description:
PRIORITY 
     This application claims priority of the provisional application #60/225,975, filed Aug. 17, 2000. 
    
    
     FIELD OF THE INVENTION 
     The invention pertains to permanent magnet devices for separating stacks of sheets of ferrous steel. 
     BACKGROUND OF THE INVENTION 
     The use of fanner magnets is well known in the manufacturing arts. Fanner magnets serve to fan out or separate sheets in a stack of metal sheets, thereby facilitating the movement or transfer of sheets utilizing handling devices, such as pickups, suction cups, or other lifting or moving devices. Such magnets operate on the principle of creating repelling polarities among the individual sheets. 
     There are a wide variety of methods used for separating magnetic sheets. One example is found in U.S. Pat. No. 4,815,916, issued to James A. Beck, and teaching a plurality of magnetic elevator devices disposed along the sides of a vertical stack of magnetizable steel objects, such as sheets. Another type of device is found in U.S. Pat. No. 4,743,006, issued to Fred Bole, Jr., et al., and discloses a fanner magnet assembly including a power-actuated carriage for movement relative to a stack of sheets. 
     However, prior sheet separators are limited in their operation, and are not particularly well adapted to separating palletized sheets of metal. When placed in pallets, a stack of steel sheets (or sheets of other ferro-magnetic composition) is typically aligned and positioned between pins on a pallet to restrain the lateral movement of the stack of sheets while the pallet is being transported and processed. Typical pallets are equipped with a large number of pallet pins located around the perimeter of the pallet which surround the sheets. These pins are placed in cavities, thereby creating a “fence” of pallet pins surrounding the sheets of ferrous material. Pallet pins may be threaded into corresponding threaded cavities in a pallet, or may be mounted using “bayonet” type locking whereby the pallet pin is engaged and disengaged relatively quickly from the cavity in a pallet by placing a plurality of pallet pins completely surrounds the steel sheets, the sheets are effectively restrained from movement in relation to the pallet. 
     In the manufacturing environment, pallets equipped with pallet pins surrounding a stack of metal sheets are transported to the vicinity of an industrial processing machine. Typically, an external-type sheet fanner, which may be magnetic, is positioned close to the pallet to facilitate separation of the upper sheets from the stack. The uppermost sheet is then engaged by either a magnetic or suction-type gripper which will lift the uppermost sheet vertically from the stack, and free from the pallet and associated pins. 
     Improvements to this process can be realized by utilizing specialized magnetic pallet pins of the type described herein. 
     SUMMARY OF THE INVENTION 
     The invention is a new type of pallet pin which contains an integral rotating magnet assembly. The integral magnet assembly is mounted within an inner cylindrical cavity of the pin and is attached to an axially extending member which is coaxial with the pin&#39;s circumference. Although the magnet is of approximately the same length as the pin&#39;s cylindrical length, it occupies only a portion of the circumference defined by the interior of the cylinder. 
     Magnetic pallet pins of this description are substituted for traditional non-magnetic pallet pins in one or more locations around the perimeter of the pallet. The internal magnet assemblies are rotatable within the cylinder, and thereby positioned either away from or adjacent to the sheets of metal carried by the pallet. When the magnets are rotated into a position in proximity to the sheets in the stack, the sheets are temporarily magnetized such that identical magnetic polarity exists at the edges of the sheet proximate to the pallet pin. This causes the sheets to repel one another and separate, thereby facilitating their removal from the stack. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cutaway side view of the invention showing the pallet pin and its internal magnet. 
     FIG. 2 is an elevation view of the invention. 
     FIG. 2A is a close-up view of the bottom portion of the invention. 
     FIG. 3 is a top view of the invention. 
     FIG. 4 is a top view of the invention, minus the upper components, revealing the placement and orientation of the internal magnets. 
     FIG. 5 is a bottom view of the invention. 
     FIG. 6 is a perspective view of the internal components of the invention. 
     FIG. 7 is a perspective view, showing a typical application of the invention in relation to a pallet and associated workpieces. 
     FIG. 8 is a perspective view of the invention showing a hexagonal locating pin. 
     FIG. 9 is a perspective view of the invention showing a T-shaped locating pin. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention and its objects will be best understood first by reference to FIG.  1  and FIG. 4, showing the magnetic pallet pin assembly  10  consisting of a preferably stainless steel cylindrical housing  12  having a bottom plug  14 , a top bushing  16  and upper housing element  23 . All of the foregoing housing elements serve to house rotating center element  30  to which are affixed one or more magnetic elements  20  and  22  positioned along the longitudinal axis of element  30  and affixed to it by suitable means. A portion of the interior cavity  18  of housing  12  defines a space opposite the magnetic elements. Rotatable center element  30  is affixed through bushing  16  to a lifting element  24 . Center element  30 , with attached magnets  20  and  22  is rotatable relative to housing  12  by manually rotating element  24  around the central longitudinal axis of housing  12 . Such rotation of element  24  serves to reposition magnets  20  and  22  in relation to the circumference of housing  12 , permitting the operator to selectively position magnets  20  and  22  in relation to housing  12 . 
     Housing  12  is further provided, as shown in FIG. 2, with a fastening surface  40  and locating pin  42  adapted to engage with a cavity ( 70 ) on a corresponding pallet ( 64 ). 
     Rotation of the center element  30  and its associated magnets, accordingly, serves to move the magnetic elements  20  and  22  of the invention nearer or further from the metal sheets which a plurality of the pallet pins surrounds, when placed in position on a typical sheet-carrying pallet. Rotation of the center element  30  to a position in proximity to the sheets thereby serves to separate the upper sheets from the stack as the sheets become magnetized. The number of pallet pins utilized for this purpose on any pallet is regulated by the size and weight of the sheets to be separated, and the degree of separation required. It will be appreciated by those skilled in the art, however, that it is necessary to use pairs of pallet pins for each application, one such pallet pin providing a north polarity and one such pallet pin providing a south polarity. 
     The details of the operation of the invention can be further understood by reference to FIG. 6, which shows in perspective, element  30 , a plurality of magnetic elements  20  and secondary magnetic elements  22 . Magnetic elements  20  and  22  can be seen in top view in FIG.  4 . By utilizing progressively smaller cross sections for magnetic elements  20  and  22 , it can be seen that it is possible to place magnetic elements  22  in relatively close proximity to the side wall of cylindrical housing  12 , thereby bringing magnetic elements  22  in proximity to the sheets which will be fanned by operation of the invention. As is depicted in FIG. 6, there are preferably a plurality of primary magnetic elements  20  arrayed from the top to the bottom of rotating element  30 . A plurality of secondary magnetic elements  22  are then affixed to magnetic elements  20 . The magnetic elements  20  and  22  are oriented so as to place the north pole of magnetic elements  22  outermost, in certain assemblies  10 , while orienting all of the south poles outermost in others. This will insure that the sheet fanners, when operated in pairs, will suitably magnetize sheets to create the desired fanning affect. 
     The assemblies  10  formed of rotating element  30  and magnetic elements  20  and  22  is placed within the interior cavity  18  of housing  12 . Rotating element  30  is attached to upper housing element  23 , which in turn, is attached to pivot channel  25 . Rotating handle  24 , preferably circular in cross-section, is fitted into channel  25 , and is permitted to rotate within channel  25  to permit handle  24  to be folded downward out of the way during storage or operation of the system. 
     Typically, each pin fanner magnet assembly  10  is provided with a locating pin  42  which may be hexagonal, round or T-shaped in cross-section. As shown in FIG.  2  and FIG. 2A, the locating pin  42  is provided to engage each pin fanner assembly  10  with a cavity on a corresponding pallet. In this fashion, each assembly  10  remains securely positioned in relation to said pallet, ideally proximate to a station for the placement of sheets to be fanned. 
     Hexagonal and T-shaped locating pins, as shown in FIGS. 8 and 9, provide the additional advantage of being able to secure the housing of assembly  10  from rotation once the assembly  10  has been placed in position on the pallet. As shown in FIG. 5, by placing the locating pin  42  off the center axis of the assembly  10 , the assembly  10  may be rotated to a position closer to or more remote from the edge of a sheet of workpieces placed on the pallet. 
     To facilitate lifting, carrying and positioning of the assembly  10 , each assembly  10  is provided with a lifting handle  50  which is secured to the exterior of the cylindrical housing  12  by fasteners, welding, adhesives or other acceptable fastening means. 
     Also in this embodiment, upper housing element  23  is provided with a marker  48 , indicating the active position of the array of magnets  20  and  22  contained within the housing  12 . This visual indicator permits the operator to readily ascertain the position of the magnetic array in relation to both the housing  12  and the workpieces being formed. 
     In operation, as shown in FIG. 7, a stack  60  containing a plurality of workpieces  62  is positioned on a non-magnetic pallet  64 . A pair of magnetic pallet pin assemblies  10  are secured in cavities  70  provided on such pallet, by engagement of locating pins  42 . The internal magnetic elements and rotating element are oriented by rotating handles  24  to position the magnetic elements adjacent the edge of the workpieces  62 . The magnetic field induced in the workpieces  62  creates like polarity at the edges of said workpieces  62  adjacent to each assembly  10 , causing the workpieces to repel one another and separate. Once separated, the workpieces may be easily grasped and separated from the stack of workpieces  62  by gripping arms, suction cups, or comparable lifting devices. Further rotation of handle  24  and upper housing element  23  through an arc of 180 degrees locates the internal magnetic elements on the side of the assembly  10  opposite the workpieces  62 , resulting in the loss of the effective magnetic field affecting the workpieces  62 , and allowing the workpieces  62  to again collapse to an unseparated stack. 
     It will also be appreciated from examining FIG. 7, that the positioning of the stack  60  of workpieces  62  in relation to the pallet  64  is aided by one or more non-magnetic pallet pins  68  which engage cavities  70 , thereby limiting the horizontal movement of workpieces  60  in relation to stack  64 . And, although cavities  70  are depicted in FIG. 7 as cylindrical, such cavities may, in alternative embodiments, be hexagonal, T-shaped, or otherwise configured so as to perform the function of locating desired points on the outer circumference of assemblies  10  and pins  68  in relation to the edges of the stacks  60 . By providing assemblies  10  and pins  68  with locating pins  42  which are offset from the central axis of assemblies  10  and pins  68 , as shown in detail in FIG. 2A, the central longitudinal axes of assemblies  10  and pins  68  may be positioned closer to or further away from the edges of stack  60 . In this fashion, stack  60  may be restrained from horizontal movement in relationship to pallet  64 , but still be provided sufficient clearance from pins  68  and assemblies  10  to permit effective fanning action, and allow workpieces  62  to be lifted from the stack  60 .