Note: Descriptions are shown in the official language in which they were submitted.
CA 02213376 1997-08-19
HAND TOOL WITH RESILIENT GRIP
This invention relates to hand tools, and in particular to a hand tool such
as a wrench (open end, combination, adjustable, pipe, or ratchet driver), having a
5 resilient grip portion.
Traditionally, wrenches have been manufactured by hot drop forging or
casting for example, then trimming as required, broaching for sizing, polishing the
surfaces, stamping/embossing/engraving information as required, and finally plating
with chromium.
In the invention, the wrench has a metal core, with a substantial portion
of its handle portion having a resilient material integrally bonded thereto to provide a
somewhat resilient grip. The resilient material may be a natural rubber or a
thermoplastic. Preferably, the metal core has at least one opening therethrough,
through which the resilient material passes for integral bonding with itself. Alternatively,
the core may have a number of grooves or ribs for the resilient material to extend into,
for better bonding and prevention of slippage relative to the metal core. The wrench is
produced by first producing a metal core, next plating at least operative portions of the
wrench, and then injection molding a thermoplastic material over the core, or laying
natural rubber over the core and then vulcanizing.
The invention will now be described with reference to the accompanying
drawings, by way of example only, in which:
Fig. 1 is a side view of the wrench's core;
Fig. 2 is a plan view of the wrench's core;
- 1 -
CA 02213376 1997-08-19
Fig. 3 is a cross-section of the core;
Fig. 4 is a side view of the finished wrench, with the plastic or rubber grip
portion extending the entire length of the handle portion;
Fig. 5 is a plan view of the finished wrench;
Fig. 6 is a cross-section of the finished wrench;
Fig. 7 is a side view of the core of an alternative embodiment of the
wrench;
Fig. 8 is a plan view of the alternative embodiment's core;
Fig. 9 is a cross-section of the alternative embodiment's core;
Fig. 10 is a side view of the finished alternative embodiment of the
wrench, in which the plastic or rubber grip portion covers only the central portion of the
handle;
Fig. 11 is a plan view of the finished alternative embodiment;
Fig. 12 is a cross-section of the finished alternative embodiment;
Fig. 13 is a side view of the core of a second alternative embodiment of
the wrench;
Fig. 14 is a plan view of the second alternative embodiment's core;
Fig. 15 is a cross-section of the second alternative embodiment's core;
Fig. 16 is a side view of the finished second alternative embodiment of the
wrench, in which the plastic or rubber grip portion covers only the middle of the central
portion of the handle, leaving metal edges exposed;
Fig. 17 is a plan view of the finished second alternative embodiment;
CA 02213376 1997-08-19
Fig. 18 is a cross-section of the finished second alternative embodiment;
and
Fig. 19 is a side view of another very similar embodiment, in which the
plastic or rubber portion has an unribbed outer surface.
Fig. 20 is a top view of an alternative embodiment of the invention;
Fig. 21 is a cross-sectional view of the alternative embodiment of the
invention;
Fig. 22 is a cross-sectional view of the alternative embodiment of the
invention showing the inclined recess;
Fig. 23 is a top view of the connecting member according to an alternative
embodiment of the invention;
Fig. 24 is a top view of two wrenches joined to the connecting member
according to the alternative embodiment of the invention;
Fig. 25 is a cross-sectional view of two wrenches joined to the connecting
member according to the alternative embodiment of the invention;
Fig. 26 is a top view of an alternative embodiment of the invention;
Fig. 27 is a side view of the alternative embodiment of the invention;
Fig. 28 is a bottom view of the alternative embodiment of the invention;
Fig. 29 is a cross-sectional view of the alternative embodiment of the
invention;
Fig. 30 is a cross-sectional view of the alternative embodiment of the
invention showing the magnet;
CA 02213376 1997-08-19
Fig. 31 is a side view of the alternative embodiment of the invention
showing the hanger assembly;
Fig. 32 is a front view of the alternative embodiment of the invention
showing the hanger assembly; and
Fig. 33 is a front view of the alternative embodiment of the invention
showing the hanger assembly securing a number of wrenches.
In the invention, the wrench is first hot drop forged, and then trimmed and
slotted to produce the core 1 shown in Figs. 1 to 3. Broaching is then carried out for
proper sizing, and polishing is carried out. However, only the wrench ends 2 need to
be polished, since only the ends are exposed. This results in a significant cost saving.
Stamping/embossing/engraving is not required at all, which results in further savings.
The next step is plating with zinc or nickel. Only the exposed ends of the
wrench need to be plated, resulting in a cost saving and a substantial environmental
benefit. The environmental benefit is by virtue of less plating being involved, and by
virtue of the fact that either less chromium or no chromium at all can be used in the
plating. Chromium is commonly used in wrenches to avoid rusting resulting from
contact with perspiration, etc.. That is less of a factor in this case since only the ends
are exposed, and they do not come into contact with the hands as much.
The next step is either injection molding of a suitable resilient material 3
20 such as natural rubber or any thermoplastic material such as, but not limited to,
SANTOPRENE (trademark) or ENGAGE (trademark), vinyls, thermoplastic resins,
urethanes, SURLYN (trademark), etc., or laying on of natural rubber which is then
vulcanized. This produces the shape shown in Figs. 4 to 6. Contrasted with merely
CA 02213376 1997-08-19
overlaying a layer of plastic or rubber as may have been done in the past, in the
invention the plastic or rubber becomes an integrally bonded portion of the handle.
Thus the core does not have the shape of a conventional wrench handle, but instead
is configured to allow for a substantial rubber or plastic portion which is an integral part
5 of the handle rather than being essentially an add-on, and which will normally be
designed to give the handle a final shape which is somewhat different from that of the
core alone.
As one example, the ENGAGE (trademark) material mentioned above is
suitable in that it is a polyolefin elastomer produced by DuPont Dow Elastomers,
10 supplied in the form of low density free-flowing pellets. Its hardness (Shore A) is
typically 72, its flexural modulus (tangent) is 3,070 psi, and its flexural modulus (secant)
is 2,560 psi. Other properties are readily available to the public through published
product specifications. These properties represent one example of a suitable material,
but it should be apparent that a wide range of these properties would still achieve the
15 desired result.
There is no need to engrave or otherwise place markings in the metal,
since the brand, size, applicable warnings, part numbers, etc. can be introduced into
the surface of the plastic or rubber during the molding or vulcanizing process, i.e. as
part of the mold. This facilitates, for example, colour-coding for both metric and SAE
20 sizes, to assist in identification and selection of the correct tool.
As examples of the grips, Figs. 1 to 6 illustrate the preferred embodiment
in which the plastic or rubber grip covers substantially all of the wrench except for the
two end portions. Figs. 7 to 12 show an embodiment in which only the central portion
CA 02213376 1997-08-19
of the handle 4 is encased in plastic or rubber 6, the distal ends 5 of the handle portion
being provided with a matte finish or the like, such as by sandblasting.
Figs. 13 to 18 illustrate an alternative embodiment, in which the handle
7 is not fully encased. The plastic or rubber 8 is molded onto the handle as shown,
5 leaving the outer edges 9 of the handle exposed.
Fig. 19 shows a configuration for the outer surface 10 of the plastic or
rubber, which is not ribbed. This may be preferable in terms of being easier to clean
and less prone to dirt or grease accumulation. The surface preferably has a somewhat
textured surface, which may or may not be in bands as illustrated.
In each case, whether with a wrench or with other tools, the handle is
preferably provided with one or several slots or holes, through which the plastic or
rubber can flow to ensure better bonding of the plastic or rubber. In alignment with one
of the slots, an optional hole through the rubber or plastic can be provided to facilitate
hanging the wrench from a nail or peg or the like. Instead of slots or holes, grooves or
ribs could be forged onto the shaft around which the material is molded or vulcanized.
This will prevent slippage of the rubber around the shaft while in use.
The invention thus produces a number of advantages set out below
First of all, it produces a "warm feel" of rubber instead of steel on the grip
area.
It provides a greater comfort factor, by virtue of the handle being rounded
and somewhat resilient instead of straight and rigid.
CA 02213376 1997-08-19
Superior slip resistance is provided by the plastic or rubber, ensuring a
safer more secure grip even with greasy hands. A smootherfinish will facilitate cleanup
of oils and grease after use.
The slightly resilient grip provides better shock and vibration isolation and
5 resistance.
The sizes, brand names, warnings, etc. molded into the rubber handles
are more "user friendly", and offer the possibility of producing color-coordinated
handles, for example blue for SAE sizes and red for metric sizes.
The manufacturing process is more cost effective and more
10 environmentally friendly than previous processes, particularly by virtue of less chromium
or no chromium being used in plating.
The handle design and slight resilience thereof reduces fatigue in the
worker's hand.
A weight reduction of approximately 10 to 17 percent may be achieved
15 with little or no loss in strength.
The handle may provide a degree of electrical insulation.
A number of useful features may be molded to the rubber handles at low
cost. For example, Figs. 20 - 22 show an alternative embodiment of the invention,
where a male T-slot 15 is molded within one side of the resilient handle 3, and a female
20 T-slot 16 is molded to the other side of the handle to accept the male slot of an identical
wrench handle. A number of wrenches can then be attached to each other for easy
storage. In addition, an inclined recess 17 is defined within the handle so that the
wrench may be suspended from a hook or other member (not shown).
CA 02213376 1997-08-19
Figs. 23 - 25 show another alternative embodiment where two male T-
slots 15 are molded to opposing sides of a handle 3 and are secured within a female
T-slot 18 defined within the sides of a connecting member 19.
Figs. 26 - 30 show an alternative embodiment where a pocket 20 is
5 defined within a side of the handle to accommodate a magnet 21 to allow the tool to be
stored against a metal surface. The handle prevents the magnet from coming into
contact with the metal section of the tool, and, accordingly, the magnet does not
magnetize the tool. A rubber cover (not shown) may be pulled over the magnet when
stored in a tool case. Two notches 22 are defined within each side the handle to mate
10 with double hooks 23 protruding outwardly from a hanger assembly 24 adapted to
accommodate any suitable number of wrenches.
As best shown in Figs 31 - 33, the hanger assembly comprises a body 25
of any suitable shape, such as a generally flat rectangular body shown in the drawings,
and an integrally molded handle 26 is secured to the top edge thereof. A plurality of
15 double hooks 23 are aligned vertically along the center of the body, and secured thereto
by any suitable means, such as, for example, the hooks being integrally molded to the
body. A number of hand tools of various sizes manufactured according to this
embodiment of the invention can be stored on the hanger assembly and carried by the
user to the job site.
