Cutlery – Carton openers
Reexamination Certificate
1999-06-09
2001-03-06
Watts, Douglas D. (Department: 3724)
Cutlery
Carton openers
C030S294000
Reexamination Certificate
active
06195896
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to safety knives of the kind comprising a handle, a main blade mounted on the handle with at least a portion of the cutting edge of the blade projecting from the handle, and a guard mounted on the handle to shield the projecting portion of the blade.
SUMMARY OF THE INVENTION
According to the present invention, in a safety knife of this kind, the guard comprises a further blade which is mounted on the handle in generally the same plane as the main blade and has a cutting edge at least a part of which is directed towards said projecting portion of the main blade.
Preferably at least a portion of the cutting edge of the further blade is concavely curved and extends around a part of the cutting edge of the main blade.
Preferably the concavely curved portion of the further blade extends around a junction between the cutting edge of the main blade and an adjacent edge of the main blade. The adjacent edge of the main blade may be sharpened or unsharpened.
The portion of the concave edge of the further blade which extends around a part of the cutting edge of the main blade preferably extends at an acute angle to the cutting edge of the main blade. For example, said portion of the curved edge may extend generally parallel to an edge surface of the handle from which the main blade projects, or at a small angle to the parallel direction.
The further blade may be formed at one end with a tang having an inner edge, which forms part of said concave edge around part of the cutting edge of the main blade, and an outer edge. Preferably the free end of the tang is at least partly rounded.
Preferably also the distance of the tang from said edge surface of the knife handle is such as to engage the finger of a user should it move towards the exposed cutting edge of the main blade, thereby to prevent, or reduce the risk of, the finger coming into cutting contact with the exposed portion of the main blade.
In any of the above arrangement a portion of the cutting edge of the main blade may project at an obtuse angle beyond an edge surface of the handle of the knife.
The main blade may have an angle between the exposed portion of its cutting edge and the blade edge which is adjacent said exposed portion which is about 90°. Alternatively the angle between said edges may be less than 90°. The main blade may be trapezium shaped so that, by reversing the blade longitudinally, opposite pointed ends of the blade may project beyond the edge surface of the knife handle.
The further blade may be a cutting blade of the kind comprising a central portion having front and back unsharpened edges and two similar hook-shaped portions at opposite ends thereof, each hook portion comprising an inner concave sharpened cutting edge and an outer unsharpened edge. In this case the knife may include two main blades, cooperating with the two hook portions respectively. Alternatively, each hook portion may cooperate with a different portion of a single main blade.
In the case where the main blade is trapezium shaped an unsharpened end edge of the main blade may extend along or substantially parallel to the unsharpened inner edge of the hooked blade with the point between said end edge of the main blade and the cutting edge of the main blade projecting into the concavely curved cutting edge of the hooked blade so that the point of the main blade lies adjacent the cutting edge of the hooked blade.
REFERENCES:
patent: 1562429 (1925-11-01), Unsinger
patent: 2686360 (1954-08-01), Fisher
Watts Douglas D.
Young & Thompson
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