Note: Descriptions are shown in the official language in which they were submitted.
CA 02390929 2002-06-19
PATENT
Attorney Docket No. 030157.0053
SNOW REMOVAL TOOL HAVING AN INSERT-MOLDED WEARSTRIP
AND METHOD OF FORMING SAME
' 1. Field of the Invention
The invention relates to snow tools; in particular, it relates to a snow
removal tool
having an insert-molded wearstrip.
2. Description of the Related Art
Many snow tools, such as snow shovels and snow pushers, on the market today
are
made of molded plastic. Some of these tools feature a metal wearstrip attached
to the front edge of
the tool. The function of this metal wearstrip is to reduce the wear on the
front edge of the tool as
it is used on abrasive surfaces such as asphalt and concrete. In addition, the
metal wearstrip can
provide a sharper cutting edge which allows snow and ice to be removed more
cleanly and
completely.
In general, these metal wearstrips are attached using metal rivets. Riveting
requires
that holes be formed in the plastic snowtool by drilling or molding, and
carefully aligning the
wearstrip and snowtool while rivets are inserted and clinched. A disadvantage
of riveting is that
riveting equipment is expensive and the act of riveting is costly and labor
intensive.
SLIwIMARY OF THE INVENTION
Therefore, a need has arisen for a snow removal tool having an insert molded
wearstrip that overcomes these and other shortcomings of the related art.
It is an object of the present invention to provide a snow tool having a
wearstrip
attached without using rivets or any secondary operation performed after
molding, e.g., crimping.
According to one embodiment of the present invention, a snow tool comprises a
blade portion and a wearstrip attached to each other by insert molding. Insert
molding is performed
by placing the wearstrip, which has one or more openings therethrough, in a
recess of a mold cavity.
A polymer material is injected into the mold cavity and flows through the
openings in the wearstrip.
Upon solidification of the polymer, the final molded product has a cutting
edge of the wearstrip
protruding from a front edge of said snowtool. Preferably, the wearstrip is
galvanized steel and has
a fold or ridge across it to increase stiffness of the snowtool in bending.
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CA 02390929 2002-06-19
PATENT
Attorney Dockct No. 030157.0053
It is a technical advantage of the present invention that rivets are not
required, thereby
eliminating the costly and labor intensive process of riveting. Moreover, the
present invention does
not require any secondary attachment operation performed after molding, e.g.,
crimping.
The foregoing, and other features and advantages of the invention, will be
apparent
from the following, more particular description of the preferred embodiments
of the invention, the
accompanying drawings, and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present invention, the objects and
advantages thereof, reference is now made to the following descriptions taken
in connection with
the accompanying drawings in which:
Fig. l depicts a snow tool comprising an insert molded metal wearstrip
according to
an embodiment of the invention;
Figs. 2(a), 2(b), and 2(c) depict, respectively, a top view, a cross-sectional
view, and
an expanded cross-sectional view of the snow tool shown in Fig. 1;
Fig. 3 illustrates a metal wearstrip according to an embodiment of the
invention; and
Fig. 4 depicts a method for forming a tool having a metal wearstrip according
to one
embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Preferred embodiments of the present invention and their advantages may be
understood by referring to Figs. 1-4, like numerals being used for like
corresponding parts in the
various drawings.
Although the present invention is described in the context of snow removal
tools, the
present invention is not so limited. The inventive concept can be employed in
any type of tool
comprising a wearstrip attached to moldable material.
In the preferred embodiment of the invention, a snow tool features a wearstrip
attached to the digging or pushing end (herein referred to as the blade
element) of the snow tool by
means of insert molding. Referring to Fig. 1, snow tool 100 is shown
comprising blade 110,
wearstrip 120, and connector 130 for connecting blade 110 to a shaft and
handle (not shown). Blade
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CA 02390929 2002-06-19
PATENT
Attorney Docket No. 030157.0053
110 is manufactured from a material suitable for molding, such as, but not
limited to, plastic,
preferably, polypropylene, high density polyethylene ("HDPE"), acrylonitrile
butadiene styrene
("ABS"), nylon, reinforced plastic, e.g., graphite-impregnated plastic, and
the like. Wearstrip 120
is preferably metal, e.~,, galvanized steel, but can also be fashioned from
any type of solid material,
e.g:,, ceramic, high strength polymer, or a composite material, that will
remain rigid during injection
molding and has suitable hardness for snow or ice removal.
Fig. 2(b) depicts a cross-sectional view of snow tool 100 taken along axis A-
A,
shown in Fig. 2(a). Fig. 2(c) portrays an expanded view of snow tool 100 at a
location where
wearstrip 120 and blade 110 are joined together. Wearstrip 120 comprises one
or more openings,
e.g" holes, as shown in Fig. 3, to allow blade material to flow through during
molding. Axis A-A
dissects one of these openings as shown in Figure 2(c).
Wearstrip 120 is attached by the process commonly referred and known in. the
art as
insert molding. Fig. 4 depicts method 400 for forming a tool having a metal
wearstrip according to
one embodiment of the present invention. Wearstrip 120 is placed (step 410) in
a proper recess in
an open mold cavity. The mold is closed (step 420) and the blade material,
e.g_, plastic, is injected
(step 430) and allowed to flow (step 440) through the openings in wearstrip
120 and then solidify.
Upon solidification of the blade material, the molded tool is removed (step
450) from the cavity.
After molding, the cutting edge of wearstrip 120 protrudes from the front edge
of the snowtool, while
a portion of wearstrip 120 remains within the snowtool at a sufficient depth
to provide firm
anchoring. After molding, wearstrip 120 may be shaped, if desired.
Whereas the wearstrip illustrated in Figs. 1-3 is flat and has openings, in
other
embodiments, wearstrip 120 may include a fold or ridge in order to increase
tool stiffness in bending.
In other embodiments, wearstrip 120 may be L-shaped, scalloped, notched along
one or more
surface ends, serrated, or any combination thereof, with or without
perforations, in order to improve
anchoring within the snowtool or to assist in snow or ice removal.
Other embodiments and uses of the invention will be apparent to those skilled
in the
art from consideration of the specification and practice of the invention
disclosed herein. It is
intended that the specification and examples be considered exemplary only,
with the true scope and
spirit of the invention indicated by the following claims.
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