Note: Descriptions are shown in the official language in which they were submitted.
212~34~
HOCXEY STICK SHAFT
BACRGROUND OF THE INVENTION
This invention relates to hockey sticks and more
particularly to an improved hockey stick shaft for replaceable
hockey blades and handles.
The expanding popularity of hockey at the amateur and
professional levels has been fueled by increasing spectator
interest in the sport. As a result, there has been a growing
demand for hockey equipment, especially hockey sticks.
Hockey sticks have traditionally been a one-piece
wooden structure. During a typical hockey game, a hockey stick
can impact the ice hundreds of times at force levels that often
result in fracture or breakage of the stick. Breakage of a
hockey stick occurs most frequently at the blade portion or at
the lower part of the shaft that extends from the blade
portion. It is thus fairly common for many hockey players to
replace a broken stick at least once during each hockey game.
In an attempt to improve the durability of a hockey
stick without sacrificing the characteristics of weight, feel,
and flexibility that are desirable in a hockey stick, materials
other than wood have been resorted to in constructing hockey
sticks. Thus, although a wooden hockey stick has set the
standard for weight, feel and propulsion of a puck, a new
generation of sticks have been formed of plastic and aluminum,
as well as laminates of fibrous, plastic and resinous
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21253 13
materials. Generally, plastic and aluminum provide good
strength characteristics for a hockey stick, but the weight,
wear and feel of these materials do not command universal
acceptance by hockey players.
Since most hockey players prefer a wooden hockey
blade, much attention has been directed to the development of
a durable, non-wooden hockey stick shaft that can be used with
a wooden blade but is less likely to break than a wooden shaft.
One result of such development effort is a hollow aluminum or
fibrous hockey stick shaft capable of receiving a replaceable
blade that can be formed of wood or plastic.
For example, U.S. Patent 4,086,11S to Sweet, et al.
shows a hollow hockey stick shaft made from graphite fiber and
resin. The hockey stick includes a wooden blade with a tongue
lS that engages one end of the hollow shaft and is bonded therein
with a polyester resin mixture. It has been found that hollow
shafts formed of graphite fiber and resin as disclosed in this
patent, are more durable than wooden shafts but are still prone
to fracture under the usual forces that a stick is subject to
in a hockey game.
Thus the problem of shaft breakage or fracture in a
hockey stick that includes a hollow shaft, such as disclosed in
U.S. Patents 4,591,155; 4,600,192; 5,050,878; 4,553,753;
4,361,325; 3,961,790; 4,358,113; 3,934,875 and 4,968,032, has
been alleviated but not solved since breakage and fracture are
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.,_
still common occurrences even in aluminum or fibrous material
hockey stick shafts.
It is thus desirable to provide a hockey stick shaft
that is relatively indestructible during a hockey game, permits
replaceable use of blades and an end handle, and retains the
flexibility and feel commonly associated with a wooden stick.
OBJECTS AND SUMMARY OF THE lNv~NllON
Among the several objects of the invention may be
noted the provision of a novel hockey stick shaft, a novel
hockey stick shaft having a greater resistance to breakage and
distortion than aluminum or wood shafts, a novel hockey stick
shaft which, if broken, does not splinter or produce shards, a
novel hockey stick shaft which has the feel of wood, is shock
absorbing and flexes but does not bend permanently, and a novel
method of improving the torsional strength and fatigue strength
of a tubular hockey stick shaft.
Other objects and features of the invention will be in
part apparent and in part pointed out hereinafter.
In accordance with the invention, the hockey stick
shaft is an elongated tubular member formed as a plurality of
discrete layers of bondable material, preferably bonded
together by epoxy resin.
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In a preferred embodiment of the invention, the hockey
stick shaft has a layer sequence from the outside surface to
the inside surface of the shaft of,
a) a layer of random strand mat glass fibers,
b) a layer of 0/90 balanced plain weave glass
fiber fabric or 0/90 aramid fiber fabric,
c) a layer of 0 unidirectional glass fiber roving
or 0 unidirectional aramid fiber roving,
d) two layers of +45 balanced stitched layered
aramid or +45 balanced stitched layered glass
fiber fabric, or a combination thereof,
e) a layer of 0~ unidirectional carbon fiber roving
or 0 unidirectional aramid fiber roving, and
f) a layer of 0/90 balanced plain weave glass
fiber fabric.
The hockey stick shaft is preferably formed by
pultrusion and is of substantially uniform wall thickness with
opposite open ends adapted to receive a replaceable handle and
a replaceable hockey blade.
Under this arrangement, the hockey stick shaft is
endowed with torque and twisting strength characteristics that
provide good resistance against breakage and distortion, and if
broken, the shaft does not produce splinters or shards. The
hockey stick shaft is thus non-hazardous in the event of
breakage.
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-
The invention accordingly comprises the constructions
and method hereinafter described, the scope of the invention
being indicated in the claims.
DESCRIPTION OF THE DRAWINGS
In the accompanying drawings,
FIG. 1 is a simplified schematic elevation of a hockey
stick, partly shown in section, incorporating the shaft of the
present invention;
FIG. 2 is a simplified sectional view taken on the
line 2-2 of FIG. 1;
FIG. 3 is an enlarged fragmentary detail of section 3
of FIG. 2, showing the laminate structure of the hockey stick
shaft;
FIG. 4 is a simplified schematic of the hockey stick
shaft showing the angular direction of the layup materials that
constitute the hockey stick shaft.
Corresponding reference characters indicate
corresponding parts throughout the several views of the
drawings.
DETAILED DESCRIPTION OF THE INVENTION
A hockey stick incorporating the present invention is
generally indicated by the reference number 10 in Fig. 1.
The hockey stick 10 includes an elongated tubular
shaft member 12 of generally rectangular cross section that is
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approximately 48 inches long with openings 14 and 16 at
opposite ends. The shaft 12, in cross section, has a side 30
approximately 1.2 inches wide and a side 32 approximately 0.8
inches wide. The wall thickness of the shaft 12 is
substantially uniform and can vary from about 0.070 to 0.1
inches, preferably about 0.075 to 0.095 inches, and most
preferably about 0.080 to 0.085 inches. When aramid fiber
materials are used, the wall thickness can be reduced to a
lower range of about 0.060 to about 0.070 inches.
A replaceable handle 18 includes a reduced neck
portion 22 adapted to fit into the opening 14 of the shaft 12,
and a replaceable hockey blade 20 includes a similar reduced
neck portion 24 adapted to fit in the opening 16. Preferably,
the handle 18 and the blade 20 are made of wood.
The reduced neck portions 22 and 24 of the handle 18
and the blade 20 are coated with a conventional hot melt
adhesive, which liquifies when heated and solidifies when
cooled and can easily be activated from a convenient source
such as a conventional portable hand-held hair dryer. The heat
is applied to the shaft 12 at the area of the engaged neck
portions 22 and 24, and melts the adhesive to activate the
bonding action between the adhesive, the neck portions 22 and
24 and the inside surface 34 of the shaft 12.
Referring to Fig. 3, the shaft 12 includes a layup of
discrete layers 42, 44, 46, 48, 50, 52 and 54, which can
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include unidirectional glass fiber roving, unidirectional
carbon fiber roving, unidirectional aramid fiber roving,
continuous strand random fiber mat and/or balanced plain weave
fiber fabric, and/or stitched layered fabric.
The layup sequence is the stacking sequence of the
various fiber orientations in an angular direction that is
parallel to the longitudinal axis of the hockey stick shaft.
In a pultrusion process, the fiber orientation would be
axisymmetric. The layers 42-54, in the layup sequence of Fig.
3 from the outside surface 36 of the shaft 12 to the inside
surface 34 are preferably constituted as follows:
1) Layer 42 consists of a single wrapping of a
continuous strand glass fiber mat having a
random pattern, and whose weight can vary from
about 0.5 to 2 ounces per square foot. A
suitable continuous strand glass fiber mat is
sold under the designation "8641" by Owens
Corning Fiberglass Co. The thickness of this
layer can vary from about 0.006 to about 0.010
inches, and is preferably about 0.008 inches.
2) Layer 44 consists of a single wrapping of
balanced 0/90 plain weave glass fiber fabric,
such as that sold by Mutual Industries,
Philadelphia, Pennsylvania under the brand name
"Style 2964." The thickness of this layer can
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vary from about 0.010 to about 0.014 inches, and
is preferably about 0.012 inches. When
equivalent oo/soo aramid fiber fabric is used in
place of the glass fiber fabric, the thickness
range of the layer can vary from about 0.006 to
0.014 inches, with a preferred thickness of
about 0.010 inches;
3) Layer 46 consists of 0 unidirectional glass
fiber roving, known as "continuous roving", such
as that sold by Owens Corning Fiberglass Co.,
Toledo, Ohio. The thickness of this layer can
vary from about 0.010 to about 0.014 inches, and
is preferably about 0.012 inches;
4) Layers 48 and 50 are identical and consist of a
single wrapping of balanced +45 stitched
layered glass fiber fabric, such as that sold
under the brand name KnytexT~ by Hexcel Co.,
Minneapolis, Minnesota. The thickness of each
layer 50 and 48 can vary from about 0.013 to
about 0.017 inches, and is preferably about
0.015 inches. When equivalent +45 aramid fiber
fabric is used in place of the glass fiber
fabric, the thickness range of the layer can
vary from about o.009 to 0.017 inches, with a
preferred thickness of about 0.013 inches:
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5) Layer 52 consists of 0 unidirectional carbon
fiber roving, such as that sold under the brand
name Grafil~ Grade 34-700 by Mitsubishi Grafil
Co., Sacramento, California. The thickness of
this layer can vary from about 0.010 to about
0.014 inches, and is preferably about 0.012
inches;
6) Layer 54 is identical to layer 44 and consists
of a single wrapping of balanced 0/90 plain
weave glass fiber fabric. The thickness of this
layer can vary from about o.olo to 0.014 inches,
and is preferably about 0.012 inches. When
equivalent 0/90 aramid fiber fabric is used in
place of the glass fiber fabric, the thickness
range of the layer can vary from about 0.006 to
0.014 inches, with a preferred thickness of
about 0.010 inches.
Layers 44 and 54 can also each comprise a single
wrapping of a balanced 0/90 stitched layered glass fiber
fabric, such as that sold under the brand name Knytex~ by
Hexcel Co.
In many situations it is desired to reduce the weight
or to reinforce the strength of the hockey stick shaft by the
substitution of some or all of the aforementioned layer
materials with aramid fiber materials.
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Aramid fibers are distinguished by low density, high
tensile strength, a range of tensile stiffnesses, notable
toughness characteristics, and non-linear, low-strength
compressive behavior. Fiber density is about 40% lower than
glass and about 20% lower than carbon. Tensile strength ranges
from about 500 to 600 X 103 p.s.i. Tensile modulus ranges from
about 12 to 25 X 106 p.s.i. Fiber toughness contributes to
damage tolerance. Aramid composites exhibit ductile behavior
when loaded in compression and flex and ultimate strength is
lower than either glass or carbon composites.
Aramid fiber materials are widely available under the
trademark Kevlar~ from DuPont Co., Wilmington, Delaware.
Aramid fibers, roving and fabrics in the same or equivalent
form and configuration as the corresponding glass fiber and
carbon fiber materials used in the present invention are
available from the corresponding sources of glass fiber and
carbon fiber materials.
The particular advantage of incorporating aramid fiber
materials in the inventive hockey stick shaft is reduction in
weight, and increased tensile strength, toughness and impact
resistance.
A thin outside surfacing veil (not shown) made of a
thermoplastic polyester, such as Nexus~ manufactured by
Precision Fabrics Group, Greensboro, North Carolina, is used to
provide the outer surface of the shaft with a smooth uniform
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surface. The surfacing veil is about 0.002 to 0.003 inches
thick.
The wall thickness of the hockey stick shaft without
aramid fiber materials can vary from about 0.07 to 0.1 inches,
preferably about .075 to .095 inches and most preferably about
0.080 to 0.085 inches. When aramid fiber materials are used,
the wall thickness can be reduced on the order of about 0.020
inches. The shaft 12 is preferably made using the technique of
pultrusion.
The non-0 materials are fed from rolls of about 3.5
to 4.25 inches wide. The 0 unidirectional carbon fiber
rovings can contain about 6000-48000 filaments per roving, and
preferably about 24,000 filaments per roving, which are evenly
distributed around the entire cross-section of the shaft. The
0 unidirectional glass fiber roving can vary from about 64
yards per pound yield to about 417 yards per pound yield, and
most preferably about 247 yards per pound yield. Equivalent 0
unidirectional aramid fiber roving can also be used.
In the pultrusion production line, the innermost two
layers, that is, the 0/90 glass fiber fabric and the 0
unidirectional carbon fiber roving are fed into a preforming
section and impregnated at a first impregnating zone with an
epoxy resin, such as Glastic Grade 5227789, Glastic
Corporation, Glastic, Ohio, or Shell Epon~ 828, Shell Chemical
_ 2125343
Company. Equivalent 0/90 aramid fiber fabric and 0
unidirectional aramid fiber roving can also be used.
The resins of choice for impregnating and bonding the
layup materials are epoxy resins, which have very low shrinkage
during polymerization or curing and also have high strength to
failure. Thus, epoxy resins are ideally suited for the
preparation of the composite carbon fiber hockey stick shaft.
As the innermost two layers proceed along the
production line, the two layers of +45 stitch layered glass
fiber fabric and the 0 glass fiber roving are added and
impregnated with the epoxy resin at a second impregnating zone.
Equivalent +45 stitch layered aramid fiber fabric and 0 aramid
fiber roving can also be used.
The final 0/90 glass fiber fabric, the 8641
continuous strand glass fiber mat and the surfacing veil are
then added to the production line and fed into a final
impregnating zone that surrounds the entire layup production
line. The final outside layers are then impregnated with the
epoxy resin. On a weight basis, the epoxy resin comprises
about 20% to 40%, and preferably about 30 weight % of the
hockey stick shaft. As already indicated, equivalent aramid
fiber fabric and mat can also be used to replace the glass
fiber mat and the glass fiber fabric, in whole or in part.
The layup production line is then continuously pulled
through a shaped orifice in a heated steel die to give the
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layup the geometry of the rectangular hockey stick shaft, as
seen in Fig. 2. As the materials pass through the die, the
epoxy resin and a suitable curing agent, such as methylene
diamine or a mixed amine curing agent well known in the art,
cures continuously to form a rigid cured profile corresponding
to the hollow rectangular longitudinal shape of the hockey
stick shaft.
The layup sequence in the production line is typically
pulled through a die that can preferably vary from about 2 to
3 feet in length. The processing temperatures can vary from
about 300 to 400F, preferably about 300 to 320F, and most
preferably about 310F along the first half of the die, and
preferably about 340 to 360F, and most preferably about 350F
along the second half of the die. Typical production line
speed can vary from about 6 to 14 inches per minute and
preferably about 10 inches per minute.
When the hockey stick 10 is used to hit a puck (not
shown), the shaft 12 in reaction has a tendency to twist or be
in torsion. The +45 orientation of the two layers 46 and 48
of +45 balanced stitched layered glass fiber fabric or
equivalent aramid fiber fabric is believed to provide improved
torque and twisting strength to the shaft 12. The additional
torque and twisting strength of the shaft 12 provides improved
resistance against breakage and distortion.
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.
Another important aspect of the invention is that the
0 unidirectional carbon fiber roving should not be located in
the central portion of the layup sequence. It has been found
that improved physical properties occur when the 0 carbon
fiber roving is located away from the central layer, and is
preferably located adjacent to the inside surface or the
outside surface of the hockey stick shaft.
The improvement in properties appears due to the fact
that when the 0 carbon fiber roving is located in the central
portion of the layup sequence, it does not significantly
contribute to the overall physical properties of the hockey
stick shaft. However, when it is located closer to the outer
surface of the layup sequence, improved physical properties
occur, particularly in terms of the flexural strength.
Thus, the closer the layer of 0 carbon fiber roving
is to the inner or outer surface of the shaft, the more
significant will be its contribution to enhanced physical
properties, apparently because there is not a uniform stress
state in the material. In the central portion there is almost
no stress at all because the size of the carbon fiber is not
significantly changing when there is bending. Thus, on one
side (the outer side), the carbon fiber will stretch, and on
the other side (the inner side) the carbon fiber will compress
and there is a gradient across from the center line of the
roving to the surface.
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The closer the carbon fiber roving is to the surface,
the greater effect it has in contributing to improved physical
properties. The closer it is to the center, the less it will
contribute. In a like manner, equivalent 0 unidirectional
aramid fiber roving can also be used.
Although pultrusion is the preferred method for
producing the improved carbon fiber hockey stick shaft, other
methods can also be used, such as matched die molding or hand
lamination of the multiple layers. The typical improved carbon
fiber hockey stick shaft of the present invention has a length
of about four feet. However, length can vary in accordance
with individual preference. In addition, the layup sequence of
materials can also vary.
The following examples are illustrative of the present
invention:
Example 1
In this example, A, B, C, D and E are each 8 inch wide by
12 inch long flat laminates of separate layup sequences. The
materials in each layup sequence are tabulated in Table 1. The
physical properties for each layup laminate are tabulated in
Table 2. Each line item in the layup sequence is a single
discrete layer of material. Each of the 0/90FG, 0FG, 0CF
layers were 0.012 inches thick. The 8641 layer was 0.008
inches thick and the +45FG layer was 0.015 inches thick.
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The layup was formed by placing one half of the layers
(the first four layers in the 8 layer laminates of A, D and E
and the first five layers in the 9 layer laminates of B and C)
in a mold preheated to 300F. 135 grams of Glastic 5227789
epoxy resin were poured into the center of the uppermost layer
in the mold. The remaining plies were laid on top and 1400 psi
pressure from an hydraulic press was then applied for five
minutes.
TABLE 1
A B C D E
8641 8641 8641 8641 8641
0/90FG 0CF 0/90FG 0CF 0FG
0FG +45FG +45FG +45FG +45FG
+45FG 0/90FG 0FG 0/90FG 0/90FG
+45FG 0FG 0CF 0/90FG 0/90FG
0CF 0/90FG 0FG +45FG +45FG
0/90FG +45FG +45FG 0CF 0FG
8641 0CF 0/90FG 8641 8641
8641 8641
16
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TABLE 2
Layup Sequence A B C D E
Tensile 84,060 101,000 64,740 100,200 44,430
Strength (psi)
Tensile 9.76 11.5 6.9 10.3 2.65
Modulus (psi x
lo-6)
Flex Strength 66,410 78,890 54,260 78,060 71,890
(psi)
Flex Modulus 3.89 10.21 3.16 9.68 2.66
(psi x 10-6)
Notched Izod 33.8 38.9 33.1 30.8 43.6
(ft.-lb./in.)
As seen from Table 1 and Table 2, the various
configurations in the layup sequence can be changed to achieve
the balance of properties desired by the user to achieve
desired flexibility, stiffness (flex modulus) and strength
(tensile strength).
It was observed that carbon fibers closer to the
surface gave better physical properties. The highest impact
strength (notched Izod) resulted with an all-glass fiber layup
(E). There was a higher modulus with carbon than with glass
fiber.
Example 2
A fifteen year old Canadian hockey player used a
number of different hockey sticks over a two-day period,
including two prototypes of the inventive hockey stick shaft.
The sticks were used to hit a standard National Hockey League
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hockey puck several times over a smooth ice surface on a day
when the temperature was about 55. The average speed of the
puck was measured by a Sports-Star SL-300 hand held radar gun
manufactured by Sports-Star Co. of Portland Oregon. There
were appropriate rest intervals and stick rotation.
The average speed was calculated on the basis of 10
shots per day with each hockey stick, eliminating the highest
and lowest speeds. The test results are tabulated in Table 3.
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TABLE 3
AVERAGE SPEED (M.P.H.)
HOCKEY STICK MODEL DAY 1 DAY 2
1. EASTON STIFF FLEXa
HXP 4900 GOLD 67.37 68.25
2. EASTON W/ CARBON FIBERa
HX A/C 7100 EXTRA STIFF 66.38 68.00
3. EASTON GRETZKYa
EXTRA STIFF HXP 5100 70.38 70.50
4. SHERWOOD PMP 7000b
AL MACINNIS MODEL 70.50 70.75
5. CAMAXX EXTRA STIFFC
SCR 2000 72.37 71.87
6. CAMAXX STIFF FLEXC
SCR 1000 74.25 74.62
a. Easton Sports, Inc., Burlingame, California
b. Sherwood Drolet Ltd., Sherbrooke, Canada
c. Prototype of the invention. The layup sequence is as
described in the aforesaid description of Fig. 3, with each
layer having the preferred thickness. There were 10% more
carbon fiber filaments in the SCR 2000 than the SCR 1000
hockey stick shaft. Additional resin replaced the reduced
amount of carbon fiber roving in the SCR 1000 hockey stick
shaft.
Some advantages of the inventive carbon fiber hockey
stick shaft are as follows:
1) 20~ lighter than aluminum;
2) Stronger than aluminum and wood;
3) Flexes well but does not bend permanently;
4) Feels like wood as compared to aluminum;
5) Has a much better gripping surface than
aluminum;
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6) No vibrations - aluminum has tremendous
vibrations and needs styrofoam for
stabilization;
7) The blade can be installed and removed with a
heat gun rather than a blow torch and is thus
safer to use and more convenient;
8) There is efficient removal of the blade or
handle;
9) Cost is comparable to aluminum;
10) Has high capacity manufacturing capability
without production problems;
11) The stick shoots harder and faster than either
wood or aluminum;
12) Color will not chip;
13) There is a minimal fatigue factor in comparison
with aluminum. Thus the stick retains accuracy
throughout its life;
14) It is more durable and economical because there
is minimal fatigue or breakage;
15) It is safer than wood or aluminum and there are
no splinters or shards. If the stick breaks,
there is a benign fracture;
16) Blades last longer because the shaft absorbs
the impact.
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Additional advantages of reduced weight, increased
tensile strength, toughness and impact resistance are attained
when aramid fiber materials are used to replace, in whole or in
part, the carbon and glass fiber materials that form the
5discrete layers of layup material used to form the composite
hockey stick shaft.
In view of the above, it will be seen that the
several objects of the invention are achieved and other
advantageous results attained.
10As various changes can be made in the above
constructions and method without departing from the scope of
the invention, it is intended that all matter contained in the
above description or shown in the accompanying drawings shall
be interpreted as illustrative and not in a limiting sense.
