Cutlery – Cutting tools – Plural cooperating blades
Reexamination Certificate
2003-01-31
2004-11-09
Payer, Hwei-Siu (Department: 3724)
Cutlery
Cutting tools
Plural cooperating blades
C030S357000
Reexamination Certificate
active
06813835
ABSTRACT:
The present invention relates to pruning “shears” or “secateurs” comprising in conventional known manner, a cutting blade mounted to pivot about a pin so as to pivot beside a counter-cutting blade, the cutting blade presenting a plane face beside the counter-cutting blade and a beveled face on its other side extending longitudinally from a shoulder situated close to the pin to the tip of the cutting blade, the beveled face of the cutting blade presenting, in cross-section and going away from its cutting edge, a first zone making a first angle with the plane face of the cutting blade, and a second zone making a second angle with the plane face of the cutting blade, the second angle being smaller than the first angle.
BACKGROUND OF THE INVENTION
In conventional manner, the beveled face is made by machining a plane blank. The first angle and the second angle have values that are constant.
Secateurs of that type generally give satisfaction to their users.
Nevertheless, it is found that the tip of the cutting blade is somewhat fragile and can break when said tip is subjected to excessive twisting forces.
Furthermore, the muscular force that needs to be exerted in order to cut a branch increases very greatly with increasing diameter of said branch since it is necessary to cause the portion of the cutting blade close to the shoulder to penetrate under force into the inside of said branch over its entire section, and the thickness of the cutting blade increases regularly from its cutting edge.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the present invention is to remedy the drawbacks of known secateurs and to propose secateurs of the above-specified type that facilitate cutting branches of large diameter while presenting a tip that presents smaller risk of breakage.
In accordance with the present invention, in secateurs of the above-specified type, the value of the second angle has a minimum value in the region of the cutting blade close to the shoulder and a maximum value in a region of the cutting blade close to the tip of the cutting blade.
Thus, the region of the cutting blade close to the shoulder, which presents a second angle of minimum value and thus a minimum thickness, penetrates more easily into the wood, particularly into the wood of relatively stout branches. In contrast, the region of the cutting blade close to the tip of the cutting blade, in which the second angle has a maximum value, is of maximum thickness, and presents reduced risk of breakage.
In an advantageous version of the invention, the value of the second angle increases, e.g. in substantially regular manner, between the shoulder and the tip of the cutting blade.
In another variant of the invention, the value of the second angle B varies from about 6° close to the shoulder to about 18° close to the tip, and advantageously from about 7° to about 17°, and preferably from about 8° to about 15°.
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patent: WO 91/02453 (1991-03-01), None
Bachman & LaPointe P.C.
Deville SA
Payer Hwei-Siu
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