Abrading – Rigid tool – Rotary cylinder
Reexamination Certificate
2000-06-02
2002-06-04
Morgan, Eileen P. (Department: 3723)
Abrading
Rigid tool
Rotary cylinder
C451S349000, C451S541000, C451S557000, C451S558000
Reexamination Certificate
active
06398633
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a knife sharpener that has a plurality of at least three circular periphery stones held in a mounting block with the axes of the stones lying on a common plane so the stones are in a line. The peripheries of the outer or end stones overlap the center stone. Different spacings of the outer stone axes from the center stone axis form different sharpening angles on opposite sides of the center stone to provide one sharpening angle which is efficient for forming an edge, and another angle for polishing and refining the edge of a knife drawn across the stones.
Sharpening stones that are mounted in a housing that has separate guide surfaces on the housing for guiding a knife along or across sharpening stones at two different angles are known. One or more sharpening stones are provided on such prior art devices and are used individually. The separate guide surfaces for the side surface of a knife are positioned on the sharpener housing so that when a knife is placed on one housing guide surface and drawn across the stone, one side of the knife is sharpened at a set angle. This is repeated for forming an edge on a second side of the knife. The first sharpening is followed by drawing the knife across the same stone or a second stone while guided on a second housing surface that forms a different sharpening angle, in the prior art units.
The use of at least three stones for achieving a two stage sharpening process where both sides of the knife blade edge are engaged and sharpened or polished simultaneously is not shown.
SUMMARY OF THE INVENTION
The present invention relates to a compact knife sharpener that has at least three aligned stones that have outer surfaces parallel to parallel central axes. The stones are positioned side by side with the periphery of each outer or end stone overlapping the periphery of the center stone. The outer surfaces of each outer stone and the center stone taper relative to each other where they overlap to form a “bight” or notch across which the knife can be drawn.
The stones are preferably cylindrical and of the same diameter. The peripheries of the outer or end stones overlap the periphery of the center stone on opposite sides of the center stone. The spacing of the axis of a stone on one side of the center stone is different from the spacing of the axis of the stone on the other side of the center stone. The angle that is formed at the bight portion is thus different on one side of the center stone from the other side. The knife is sharpened on both sides of the blade in one pass of the knife as it is drawn across two of the stones in the overlapping or bight portion and then finished and polished as it is drawn across the bight portion on the other side of the center stone.
The peripheral surfaces need only be tapered or partially circular or cylindrical so that the surfaces are at the proper angle where they overlap and form the bight portion. The preferred, cylindrical peripheries form the proper angles when the radius of each stone is properly selected and the spacing of the axes is also properly selected.
The stones are mounted in a sharpener housing so that the cylindrical stones are placed with the axes of their peripheries defining a plane. The sharpener housing has a handle cross-section sized to fit into the square opening used for sharpening steels in a kitchen knife block. The sharpener housing of the present invention is elongated, and is relatively small in cross-section, but can be firmly gripped for sharpening knives.
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McGowan Manufacturing Co.
Morgan Eileen P.
Westman Champlin & Kelly P.A.
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