US2847212A - Method and apparatus for separating magnetic sheets - Google Patents

Description

Aug. 12, 1958 D. E. STEM 2,847,212

METHOD AND-APPARATUS FOR SEPARATING MAGNETIC SHEETS Filed Sepia. 15. 1954 INVEN 0 I E. 2 DOA/14155 57 'E BY z METHOD AND APPARATUS FOR SEPARATIN G MAGNETIC SHEETS This invention relates to a device for separating sheets of magnetic material.

Magnets were used in the past for separating sheets of magnetic materials such as sheets of metal for the purpose of facilitating the picking up and feeding of individual sheets of metal to machines or operations. In these previous devices usually a plurality of magnets are arranged on a perpendicular surface or wall to a certain height so that the upper magnets are attracted to the sheets from the top of a stack upwardly and thereby separate them. These devices were expensive, heavy to set up, top heavy and subject to breakage.

The primary object of the invention is to provide for the separation of magnetic sheets of material, a single magnet which is self-adjustable along a vertical surface so as to adjust itself to the best position for separating the top sheets of a stack of magnetic sheets.

Particularly it is an object of the invention to provide a separator for magnetic sheets which travels on a polished perpendicular surface in accordance with the balance of the horizontal components of magnetic attraction to the sheets to be separated and its gravity, as modified by a certain friction on the polished surface, so that the magnet slides down on said polished surface until such time that the horizontal component of magnetic attraction to the sheets and the vertical component gravity forces, and downward magnetic pull or component, are balanced to hold the magnet in position. As sheets are separated and removed from a stack the magnet automatically lowers itself to separate further sheets from the stack, and when these latter are removed the magnet automatically shifts downwardly again to separate the top sheets of the remaining stack until all the sheets in the stack are so separated.

I am aware that some changes may be made in the general arrangements and combinations of the several devices and parts, as well as in the details of the construc tion thereof without departing from the scope of the present invention as set forth in the following specification, and as defined in the following claims; hence, I do not limit my invention to the exact arrangements and combinations of the said device and parts as described in the said specification, nor do I confine myself to the exact details of the construction of the said parts as illustrated in the accompanying drawings.

With the foregoing and other objects in view, which will be made manifest in the following detailed description, reference is bad to the accompanying drawings for the illustrative embodiment of the invention, wherein:

Fig. 1 is a perspective view of a magnetic separating device constructed in accordance with my invention in operation.

Fig. 2 is a cross-sectional view of the device, the section being taken on lines 2-2 of Fig. 1.

Fig. 3 is a somewhat diagrammatic side view of my device in operation on a high stack of sheets.

Fig. 4 is a somewhat diagrammatic side view of my 2,847,212 Patented Aug. 12, 1958 device showing the relative position after a number of sheets are removed, and

Fig. 5 is a somewhat diagrammatic side view showing the magnet lowered to follow the reduction of the height of the stack of sheets.

In carrying out my invention, I make use of a vertical plate 1 of non-magnetic material, which covers the open side of a vertical hollow guide housing 2. A permanent magnet 3 is held in the housing 2 so that its poles 4 are held in vertically slidable contact with the inner surface 6 of the plate 1. Said inner plate surface 6 is highly polished to reduce to a minimum frictional resistance to the sliding of the magnet 3 along said surface.

The magnet 3 has a threaded stud 7 extended from its back through a vertical slot 8 of the back 9 of the housing 2. The stud 7 and slot 8 guide the magnet 3 vertically. A knurled nut 11 on the outside end of the stud '7 can be suitably engaged with the back 9 of the housing to hold magnet at top while sheets are stacked, when ready it is loosened and allowed to drop to automatic separating position.

The housing 2 has a suitable base 12 with suitable braces 13 to support the unit in vertical position. The vertical plate 1 is detachably held on the opening of the housing 2 by suitable securing elements such as set screws 14.

The intensity of magnetic field or attraction and relative weight of said permanent magnet 3 are predetermined so that the gravitational pull is counteracted by the attraction on the magnetic field at any height or level of the plate 2 generally when the resultant magnetic force is above the center of gravity of said permanent magnet. But when the resultant force of magnetic attraction by the object such as the sheets 16 approaches the center of gravity of the magnet 3, then the downward component force prevails and the permanent magnet 3 slides along said surface 6 until the horizontal magnetic attraction forces by the sheets 16 have a resultant force above the center of gravity sufiicient to overcome the gravity force and thus hold the magnetic plate 3 in position.

The aforesaid balancing of the magnetic forces occurs automatically during the separation and removal of the magnetic sheets 16. A stack of magnetic sheets 16 is placed in the usual position for operation where it is necessary to remove them from the stack, one by one. Then the magnetic separator as heretofore described is placed along the edge of said stack of sheets 16 and the magnet 3 is pulled up to its top position as shown in Fig. 3. This magnetic pull separates several of the sheets 16 at the top of the stack and pulls the ends of said sheets 16 adjacent to said plate 1 upwardly as shown in Fig. 3.

Thus the force of magnetic attraction by the sheets 16 horizontally upon the entire magnet 3 is divided over the entire surface of the magnet 3 and its magnetic field in its upper as well as in its lower area, respectively above and below the center of gravity of the magnet 3. The mag net 3 is thus held in position by the sheets 16 and vice versa. When the top separated sheet 16 is removed, then the horizontal magnetic force is lessened and the resultant horizontal component is lowered. After the removal of several top sheets 16, vertical gravity components are sufficient to overcome the horizontal component and to slide the magnet down on the surface 6 to a position where the next raised sheets 16 exert suflicient horizontal magnetic attraction to hold the magnet 3. As the magnet 3 is lowered, its lower area raises the inner edges of additional sheets 16 from the stack. Thus in sequence the top magnetic sheets 16 are removed from the stack and the magnet 3 gradually slides down in proportion to the sheets 2 removed to a position where the magnet holds the previously raised magnetic sheets 16 and is held thereby in raised position and also separates additional sheets 16 from the stack until all the sheets 16 on the stack are separated and removed and the magnet 3 reaches the bottom of the housing 2.

While the exact equation of forces as between the attraction and the gravity and the frictional systems are not exactly known, nevertheless in actual operation of the model constructed in accordance with this invention, this self adjustment of the magnet during the separation and removal of magnetic sheets from stack is accomplished by a single slidable magnet.

Fig. 3 illustrates the position of the magnet 5 where the upper area of the magnetic field is occupied or attracted by a number of raised sheets 16. Fig. 4 illustrates the position where a number of sheets 16 were removed and the relative magnetic attraction was lessened to a degree incapable of resisting gravity forces on the magnet 3, hence the magnet 3 slides down to the position shown in Fig. 5 where again a sufiicient number of sheets 16 are raised into the upper area magnetic field to resist gravity action on the magnet 3.

Iclaim:

l. A magnetic device for separating the top sheets from a stack of sheets of magnetic material comprising a generally vertical non magnetic guide element beside the stack, one side of-said element being adapted to guide the edges of said sheets at the adjacent side of said stack, a magnet slidable along the other side of said element and being adapted to hold adjacent edges of several top sheets raised from said stack, the magnetic field between said raised sheets and said magnet and the force of gravity on said magnet interacting to lower said magnet and raise further sheets from said stack 4 substantially in proportion to the removal of top sheets from the stack.

2. A magnetic device for separating the top sheets from a stack of sheets of magnetic material, comprising a generally vertical non-magnetic plate, a first face of said plate contacting the edges of the sheets on a side of said stack, a magnet freely slidable along the other face of said plate, the said magnet being so proportioned relatively to said stack of sheets as to raise sheets at the top of the stack and be held stationary by the magnetic forces between said raised sheets and the magnet and to be permitted to slide downwardly in substantial proportion to the removal of said raised sheets from the stack.

The method of magnetic separation of sheets of magnetic material from stacks, comprising the steps of 1 reely positioning a permanent magnet on a non-magnetic plate opposite the top of said stack so as to raise sheets from said stack so that magnetic attraction by said raised sheets overcomes the action of gravity, and removing raised sheets from the stack in sequence until said gravity overcomes said magnetic attraction and lowers the magnet on said plate relatively to said stack so as to raise more adjacent sheets from the stack.

References Cited in the file of this patent UNITED STATES PATENTS 1,716,602 Ross June 11, 1929 2,341,639 Mathiesen Feb. 15, 1944 2,474,141 Chatterton June 2, 1949 2,650,092 Wall Aug. 25, 1953 2,667,394 Goetz et a1. Jan. 26, 1954

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