Magnetic sheet fanner

Details Magnetic sheet fanner Magnetic sheet fanner

2000-02-23

2001-09-25

Skaggs, H. Grant (Department: 3651)

Sheet feeding or delivering

Feeding

Separators

C271S105000, C271S901000

Reexamination Certificate

active

06293538

ABSTRACT:

This invention relates to a magnetic fanner of the kind adapted to provide separation between magnetically permeable sheets arranged in a stack to facilitate the removal of the uppermost sheet from the stack.
BACKGROUND OF THE INVENTION
In the reforming of metal sheets arranged in a vertically extending stack it is common to remove the uppermost sheet from the stack and transfer it from the stack to another position where the sheet may undergo reforming procedures. If the confronting surfaces of the stacked sheets are smooth or have a film of lubricant thereon it sometimes is difficult to separate the upper-most sheet from the stack. This problem can be overcome by providing a magnetic field adjacent the upper end of the stack of sheets so as to provide a gap between the upper sheets, thereby facilitating the separation of the uppermost sheet from the remainder of the stack. Apparatus for accomplishing this objective is illustrated in a number of prior patents, of which U.S. Pat. No. 5,651,541 is illustrative and the disclosure of which is incorporated herein by reference.
It is preferred to use permanent magnets, rather than electromagnets, for the creation of the magnetic field because permanent magnets are less expensive and require less maintenance. In those instances in which the permanent magnets are very powerful, however, it sometimes is difficult to effect movement of the magnets in a direction away from the stacked sheets because the magnetic attraction is so great. Because of the power of the magnets the force which must be applied to move the magnets in a direction away from the stack of sheets may be greater than that which can be provided without risking damage to the fanner construction, or to the edges of stacked sheets, or both.
It is the object of this invention, therefore, to provide apparatus which can generate adequate force to effect controlled movements of very powerful magnets and in such manner as to minimize the possibility of damage resulting from such movements.
SUMMARY OF THE INVENTION
Magnetic fanner apparatus constructed in accordance with the preferred embodiment of the invention comprises a housing within which a piston of large surface area is reciprocable between a projected position in which the piston is adjacent a stack of sheets to a retracted position in which the piston is remote from the stack of sheets. On that face of the piston which confronts the stacked sheets are secured one or more powerful, rare earth permanent magnets. In the projected position of the piston the magnets are closely adjacent the stacked sheets, whereas in the retracted position the magnets are spaced sufficiently far from the stacked sheets as to exert relatively little attractive force on such sheets.
The piston is a double acting piston and has a seal between itself and the interior walls of the housing so that unequal pressures may exist on opposite sides of the piston for the purpose of effecting movement of the piston in a selected one of two opposite positions.
A source of pressurized fluid is coupled to rods which extend fore and aft of the housing and through the piston to provide support and guides for the piston during its movements. The rods are provided with fluid passages and appropriately placed ports through which pressurized fluid may pass into and out of the housing in such manner as to effect movements of the piston and the magnets supported thereby.
In the preferred embodiment the movements and positions of the piston and the magnet are controlled solely by the pressurized fluid, thereby dispensing with the need for springs. The rate of movement of the piston can be controlled by regulating the flow of pressurized fluid to and from opposite sides of the piston thereby avoiding such rapid movement of the piston as to cause damage.


REFERENCES:
patent: 1716602 (1929-06-01), Ross
patent: 2847212 (1958-08-01), Stem
patent: 2848227 (1958-08-01), Gulick
patent: 4743006 (1988-05-01), Belle et al.
patent: 5651541 (1997-07-01), Prime

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