Cutting blades

Details Cutting blades Cutting blades

1999-06-10

2001-01-30

Pezzuto, Robert E. (Department: 3671)

Earth working

Lawn edger

With wheel or roller

C056S256000

Reexamination Certificate

active

06179059

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to cutting blades and, in particular, to a dual blade assembly for a motorised lawn edging implement.
BACKGROUND OF THE INVENTION
The maintenance of a tidy natural outdoor landscape includes the regular edging or cutting of the growth of grass, plants and other vegetation along the edges of paths, curbs and gutters, garden plots, walls, fences, etc. Various methods have been used to perform these and similar tasks, using manual and motor-assisted equipment. The latter are tenned “edgers” and are increasing in popularity.
It is known for edgers to use a flat rectangular blade with at least one fixing hole in the blade. If only one hole is used, it is at the centre of the blade. Alternatively, a cutting disc with teeth disposed around its circumference is used.
During the edging or cutting process, and particularly with professional garden maintenance, it is desirable to minimise the overall time required to complete the task. It is also desirable to minimise the quantity of energy consumed, to increase the overall efficiency of the task.
It is also desirable to maximise the operator's comfort, which can be adversely affected when motor assisted equipment creates excessive movement and/or vibration, due to the inpact of the rotating blade on dirt, rocks and the like.
It is also desirable to minimise the storage space required by large quantities of cutting blades in the manufacturing and distribution stages of production.
Finally, it is desirable in some situations for an operator to have the ability to vary the width of the cut that the blade makes.
SUMMARY OF THE INVENTION
In the first aspect, the present invention discloses a dual blade assembly for a lawn edger, the assembly comprising first and second generally rectangular blades arranged in a substantially cross shaped configuration for rotation about a substantially central axis, each of the first and second blades having: a central region between two end cutting regions; at least one protuberance in the central region; and at least one recess in the central region, wherein the protuberance(s) of one of the first and second blades is adapted to engage with the recess(es) of the other of the first and second blades to counteract relative movement between the first and second blades about the rotational axis.
In the second aspect, the present invention discloses a dual blade assembly for a lawn edger, the assembly comprising first and second generally rectangular blades arranged in a substantially cross shaped configuration for rotation about a substantially central axis, each of the first and second blades being of substantially constant thickness prior to any deformation and having a central region between two end cutting regions, at least one of the first or second blades being deformed by having its end regions displaced axially from its central region, the axial distance between the opposed outermost surfaces of each of the first and second blades defining a cutting width, and wherein the first and second blades are arranged with the displaced end regions being disposed axially inwardly such that the cutting width of the blade assembly is less than or equal to twice the blade thickness of the first and second blade.
In the third aspect, the present invention discloses a dual blade assembly for a lawn edger, the assembly comprising:
first and second generally rectangular blades arranged in a substantially cross-shaped configuration for rotation about a substantially central axis, each of the first and second blades being of substantially constant thickness prior to any deformation and having a central region between two end cutting regions; and
means for maintaining said first and second blades in a fixed rotational relationship with respect to each other, said means comprising at least one of the first and second blades being deformed by having its end regions displaced axially from its central region forming a central deformation shaped to receive the other of the first and second blades,
wherein the axial distance between the opposed outermost surfaces of terminal cutting edges of the end regions of the first and second blades defines a cutting width and the first and second blades are arranged with the displaced end regions being disposed axially inwardly such that the cutting width as defined by the terminal cutting edges of the end regions of the first and second blades is less than or equal to twice the blade thickness.


REFERENCES:
patent: Re. 32266 (1986-10-01), Toggle et al.
patent: 2976666 (1961-03-01), Machovec
patent: 3006421 (1961-10-01), Feilbach
patent: 4653590 (1987-03-01), Shank
patent: 5209052 (1993-05-01), Carroll
patent: 5267429 (1993-12-01), Kettler et al.

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