One-piece shaft construction and a method of construction using bladder molding

Abstract

The present invention discloses a method of fabricating a composite material hockey stick shaft using internal bladder pressure molding technology. The bladder is inserted over a mandrel and composite materials are disposed on the bladder forming a soft, uncured piece. The mandrel is removed and the piece is disposed in a mold following which air pressure is applied to the bladder which deforms the piece to conform to the shape of the cavity. The addition of pressure and heat cures the composite materials and produces a finished hockey stick shaft.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to sporting equipment shafts and in particular to shafts suitable for use in high-impact, high-velocity, and high wear and tear sports such as ice hockey, street hockey, in-line skate hockey, ringuette, field hockey, lacrosse and other such sports. The present invention, by way of example only, will be described hereinafter in relation to ice hockey sticks, but it is understood that the invention herein described and claimed may be suitably adapted to other shaft applications and in particular to other sports.

[0002] At present, hockey sticks may be generally broken down into two broad categories, namely wooden hockey sticks, which shafts are generally made of wood such as any suitable hardwood, for example hickory, maple, etc., and composite sticks, which shafts are made of composite materials, such as carbon fibre, Kevlar™, fibreglass, and other such materials or combination of materials. The present invention relates to composite hockey sticks.

[0003] Composite hockey sticks generally consist of two basic components, namely an elongated, narrow shaft and a blade secured to the lower end of the shaft. Composite hockey sticks may be generally constructed by gluing, assembling or otherwise bonding together the two separately fabricated components, namely the shaft and the blade. In particular, in accordance with known methods of construction of composite hockey sticks, a tenon may protrude from the blade component, which tenon may be inserted into and secured to a hollow end of the shaft. Thus, after the shaft component is constructed, and after the blade component is constructed, the two components are mated by introducing the tenon into a hollow portion at one end of the shaft, which hollow portion is sized and configured to receive the tenon therein. Presently, adhesives, glues and other bonding agents are used to securely fasten the two components together so as to form a composite hockey stick. Thus, composite hockey sticks presently on the market may comprise a shaft and a blade which are independently fabricated, and which are then subsequently bonded together in a secondary operation. The bonded assembly, and in particular the joint, may then be camouflaged under layers of paint, fillers or other materials, in order that the consumer views the composite hockey stick as being continuous, i.e. made of one piece.

[0004] The independent fabrication of a composite shaft and blade, and their subsequent secondary bonding through the use of adhesives or other bonding agents, causes a structural stress riser or weak spot at, or in the vicinity of, the bonded joint. This stress riser may cause the shaft to become weak at or near the joint, and may often cause premature failure in the shaft when the composite hockey stick is in use. In particular, slapshots, wrist shots and other hard shots which transfer tremendous forces and stresses onto the shaft of the hockey stick, may often result in a composite hockey stick breaking at or near the joint of traditional composite hockey sticks presently on the market. The presence of a weak point is understandably not desirable in a shaft used for high-impact, contact sports such as hockey, lacrosse, etc . . . In addition, a weak point may, in some circumstances, be dangerous to other players on the ice, or to bystanders, and in any event is unacceptable to consumers who may view unfavourably expensive composite sticks which break prematurely.

[0005] It is thus an object of the present invention to provide for a composite hockey stick wherein the secondary, subsequent bonding operation of the shaft to the blade is eliminated so as to provide a one-piece shaft construction.

[0006] It is a further objective of the present invention to reduce or eliminate the stress riser or weak spot which is normally found along the shaft at the position of the joint, so as to increase the longevity, strength and serviceability, of a composite hockey stick.

[0007] It is a further advantage of the present invention to provide for a composite hockey stick having increased strength and durability in particular along the shaft thereof.

[0008] It is a further object of the present invention to provide an improved composite hockey stick, and an improved method of construction of a composite hockey stick.

[0009] It is a further object of the present invention to provide a method of construction for a composite hockey stick using bladder molding technology.

SUMMARY OF THE INVENTION

[0010] The present invention generally provides for a composite hockey stick shaft wherein the bonded joint as known today in the prior art (of the shaft component with the tenon of the blade component) may be eliminated or substantially eliminated. In particular, known composite hockey stick shaft technology, which uses a method through which two pieces of composite sticks, namely the composite shaft and the composite tenon are subsequently bonded together in a secondary step through the use of glue or another bonding agent may be eliminated.

[0011] It has been found that conventional composite hockey sticks wherein the tenon is secondarily mated to the shaft, i.e. at the lower end of the shaft, for example at 15 to 20 inches above the bottom of the blade, may have a structural riser or a weak spot at or near the bonded joint. Since it is well known that a tremendous level of stress and force is applied to the shaft of a stick during play, and in particular, during a slapshot, wrist shot or during checking, it is important to reduce or eliminate the presence of any weak point(s) on a shaft. In particular, the forces applied during play may be concentrated on the lower end of the shaft. Thus, eliminating or reducing a weak point in the shaft, and in particular, on the lower end of the shaft, may be of primary importance for the longevity and for the serviceability (performance) of the stick, in particular for professional or high caliber play. Thus, the elimination or reduction of this stress riser through a one-piece shaft may significantly improve the life and the performance of a composite hockey stick.

[0012] The present invention is directed at providing a unitary, or one-piece composite hockey stick shaft, wherein the composite shaft and the composite tenon may be mated, before the application of any or substantially any pressure to the shaft and to the tenon for curing of the composite materials. Thus, in accordance with the present invention, the curing of the shaft and of the tenon and the bonding of the shaft and of the tenon together may occur at the same time, once the tenon is mated to the shaft. In this manner, the resulting composite hockey stick may be made as much as possible as a true, unitary or one pieces stick.

[0013] Conventional composite hockey sticks may be manufactured in several steps. In accordance with one embodiment, the present invention departs from that approach in some ways, namely in that the curing, i.e. final curing, of the composite materials of the shaft and of the tenon is delayed, or at least partially delayed, until the previously constructed tenon is mated to the previously constructed shaft. Thus, because an uncured, or partially uncured, composite tenon is introduced into an uncured or partially uncured shaft (or vice versa), the curing of the shaft and tenon or the final curing or the completion of the curing of one or both of the shaft or tenon occurs after the mating of the two. The resulting shaft/tenon combination may therefore result in a single continuous piece wherein the curing, or the final curing of the material, will occur after mating. In this manner, the material of the tenon, and the material of the shaft may be bonded together and cured in a single step/operation occurring at the same time, which may result in said materials being of a unified single bond.

[0014] Traditional composite hockey stick shaft construction may be accomplished in a number of ways. Manufacturers may begin with what are known as prepregs, i.e. composite materials which may be pre-impregnated with resins, such as epoxy resins or any other resins, composite materials having any number of properties. Any number or combination of composite materials may be used in the construction of composite shafts, such as carbon fibres, Kevlar™, fibreglass, viscoelastic film adhesives, and so on. In particular, fibres, such as carbon fibres, may be disposed so at to be unidirectional or may be woven in any number of orientations, for example, orientation of ±90 degrees to the longitudinal axis of the shaft. The prepregs may also be braided, or incorporate therein any number of other materials or combination of materials. The prepregs may be purchased frozen from a manufacturer, and kept in a freezer prior to their use (application), in order to reduce or retard the curing of the resin(s).

[0015] The fabrication of the shaft and of the tenon may occur in a variety of ways. A form, known as a mandrel, made of steel, aluminum or other material may be used around which the composite materials may be wrapped, woven or applied, or any combination thereof. The core may then be removed following the application of pressure. Some manufacturers may use a foam core which is left inside the finished, i.e. cured, shaft. The subject matter of the present invention may be used with composite shafts and tenons which are constructed in any number of ways, using any number or combinations of materials, so long as they utilize the method of mating the shaft and the tenon.

[0016] In addition, the present invention may eliminate or reduce the need for body fillers, some known as Bondo™, to cover the manufacturing joint of some composite hockey sticks presently sold on the market. This body filler may often be used to mask the joint and to give the impression that the shaft-tenon combination is a seamless one. Naturally, the use of additional material whose use is only cosmetic and therefore not structural, adds only weight, without any resulting increase in performance, such as strength or resilience. This results in a heavier stick without any compensating advantage and is therefore to be avoided.

[0017] In accordance with a further particular aspect of the present invention, there is provided for a method of manufacture wherein bladder pressure technology is utilized to apply internal pressure to the composite materials which are used in the construction of a composite shaft so as to cure the resins impregnating the composite materials. Further, the present invention provides for a hockey stick shaft which is constructed using said method of manufacturing. In accordance with this embodiment, the pressure which may often be applied to cure the resin soaking composite material may be accomplished through the application of internal pressure against a stationary outside object which may resist the application of internal pressure.

[0018] In accordance with a particular aspect of the present invention, the method of construction of a composite hockey stick provides for the use of a mandrel, i.e. a form, which have a generally round or circular constant cross-section and which has an elongated length, namely slightly longer (for example 5%, longer) than the finished shaft of the hockey stick to be assembled. The cross-sectional shape of the mandrel may be other than circular, i.e. it may be oval or rectangular, and may not be constant throughout the length of the mandrel, although difficulties in applying, i.e. rolling the composite material thereto may have to be overcome. The mandrel may also combine several different shapes and sizes. The mandrel may be sized so as to have substantially the same size (circumference) as the size, i.e. outside diameter of a finished hockey stick shaft. For example, the circular mandrel may have a circumference which is approximately 95% of the total outside linear dimension of the finished rectangular cross-sectioned hockey stick shaft. Alternatively, the mandrel circumference may be anywhere from 80% to 99% of the outside dimension of the finished shaft.

[0019] Prior to assembling the hockey stick shaft on the mandrel, the mandrel is first fitted with a bladder thereon, which is inserted over one end and pulled over the mandrel to the other end thereof. The bladder may be shaped like a sheath or sleeve and is closed off (or may be closed of after insertion) at one end so as to be air (i.e. fluid)-tight. Generally, the bladder may be tight fitting on the mandrel, although it is understood that it may be somewhat loose about the mandrel so as to facilitate the subsequent removal of the mandrel. Although a variety of materials may be used as a bladder, such as nylon, rubber, silicon and latex, it is in any event preferred that the bladder may be as thin as possible, yet strong enough to withstand the rigors of inflation, as well as heat and pressure application which are to be applied during the construction of the hockey stick shaft. In addition, the bladder may be of sturdy construction so that more than one inflation and heat/pressure application may be applied to the construction of a shaft, and such that the bladder may be re-used in the construction of more shafts. In accordance with a particular embodiment, the thickness of the bladder may be {fraction (2/1000)} of an inch thick. In any event, the bladder must be suitable for its intended purposes, and in accordance with a particular application, be able to withstand pressure in the range of 0 to 200 pounds per square inch, and temperatures of over 290° F.

[0020] The mandrel having been sheathed with a bladder, the prepregs as previously described are applied thereon in any variety or combination of manners, using one or more combinations of several composite materials. In accordance with one particular embodiment, the prepregs may be rolled on the mandrel, either manually or mechanically. During the application of the prepregs, a slight pressure may be applied thereon, typically of the order of 10 to 20 pounds per square inch. This pressure, known as ‘bulking pressure’, may be used to remove entrapped air which may be found in the prepregs, or between layers of prepregs, as a result of their application, as well as to consolidate the layers of composite materials together on the mandrel. Although a small amount of curing of the composite material may occur during the application of bulking pressure, this may not the curing necessary to solidify the composite material to their final and desired form and strength. As may be understood to one versed in the art, the prepregs may be applied in any manner or combination of manners, and for example, may be applied so as to be disposed at a particular angle or combination of angles in relation to the longitudinal axis of the shaft. Further, the prepregs may also be applied on the bladder in a pre-assembled manner.

[0021] Once the prepregs have been applied as desired or required, the mandrel may be removed, leaving behind the bladder and the prepregs which are disposed thereon. The mandrel may be removed through the application of manual or automated mechanical pressure, through, for example, the use of a fixture affixed thereon, and/or through the use of a twisting motion so as to disengage and pull out the mandrel. At this point, the prepregs may have the consistency of putty, or other soft, deformable materials, and may, for example, be (slightly) deformable through the application of gentle, manual pressure. As may be understood, once the mandrel is removed, there is left a hollow, cylinder-shaped, thin-walled combination of soft prepregs applied to the outside of the bladder. The whole combination may then be ready for further processing.

[0022] Once the mandrel is removed, the prepreg-bladder combination, known as the piece, may be inserted inside a hollow mold or cavity, which may be known as a tool. The tool may be cut, made or constructed from a suitable material, such as steel, aluminum, brass or other material and may, for example, be substantially elongated, and U-shaped in depth. The purpose of the mold may be to help impart the final shape of the shaft to the piece, both longitudinally and cross-sectionally. Thus, in accordance with a particular embodiment, the tool may be made with a computer numeric cutter (CNC) machine, which may make one or more cuts or incision into a die, which may be roughly the shape of a finished hockey stick shaft, i.e. it has substantially the length of a hockey stick shaft and (a portion of) its cross-sectional depth.

[0023] It is understood that the tool may need two or more components in order to be able to function as a mold for imparting the final shape to the shaft. For example, the tool may comprise a lower cavity and an upper cavity, each having substantially the same size, configuration and shape so as to simply be the mirror image of the other, i.e. inverted. In this embodiment, the depth (i.e. the depth of the hole) of each of the lower cavity and upper cavity may be substantially the same. Alternatively, the tool may have an upper and a lower cavity which are not identical in size, one being deeper than the other. In a further embodiment, the tool may only have a lower cavity, into which the piece is to be disposed, and an upper cavity which is only to act as a lid therefor. In this manner, substantially all of the shape of the shaft is imparted by the cavity, with the lid acting to keep the piece in the tool. As may be understood, the tool may be configured and disposed in a number of manners.

[0024] In any event, the cavity of the tool, namely the upper cavity and the lower cavity may be configured and disposed so as to mirror the outside shape, size and configuration of a finished hockey stick shaft. For example, the tool may be elongated (up to 60 or 70 inches long), and may have two major surfaces which are spaced-apart by two minor surfaces. In accordance with a further embodiment, the major surfaces may be parallel to each other, and the minor surfaces may be parallel to each other, the whole forming a regular parallelogram. In addition, the major surfaces and the minor surfaces may each be planar. Further, the corners where the major and minor surfaces meet may be curved, rounded or beveled.

[0025] It is understood, however, that the internal shape of the tool may be so as to produce any desired or required outside shape of a hockey stick shaft. Further, while the above-described procedure has been described as encasing the piece within two equally-sized tools, it is understood that the upper and lower cavity of the tool may not be of the same size, and one may be deeper than the other. In accordance with a further embodiment, the tool may be straight, or may impart a curve to the shaft onto one or more surfaces of the shaft. Further, the curve to be imparted may be in the direction of the longitudinal axis of the shaft, or may, for example, give a convex or concave curvature to one of the surfaces, in a transverse direction to the longitudinal axis of the shaft.

[0026] As discussed above, the piece is to be placed inside the tool for further processing and shaping. However, as the piece may be round when the mandrel is removed therefrom, and it is to be placed in an elongated, U-shaped cavity, the piece may need to be slightly deformed, i.e. pushed, so as to fit therein. This deformation may be made by hand. Once the piece is disposed inside the tool, i.e. inside the lower cavity, the upper cavity is placed over the piece so as to encase the piece on all four sides. Once the piece is encased inside both upper and lower cavity, the bladder may be fitted with an attachment which may allow for it to be filled with fluid, i.e. for example, air. The order of the steps of affixing an attachment to the bladder and placing the upper cavity on the piece may be inverted. In addition, the bladder may be fitted with the attachment before the piece is inserted into the tool.

[0027] Once the piece is enclosed in the tool and the attachment affixed to the bladder, the tool may be placed into a press. Alternatively, the tool may simply be clamped or held in such a manner that it does not open up when pressure is applied to the bladder. One skilled in the art will recognize that the tool may comprise more than one cavity, for example up to four or more cavities so that the molding process may be accomplished so as to produce more than one shaft at a time. Once this tool is disposed within the press, the bladders are inflated through the application of fluid pressure, i.e. air pressure.

[0028] The pressure which may be applied may be anywhere in the range of 0 to 200 pounds per square inch. The pressure may be applied in a variety of manners, for example in a steady, even increase to a desired level, and then maintained at that level for a specific period of time, i.e. for example the duration of the curing cycle. Alternatively, the pressure may be applied quickly, almost explosively, i.e. for a rapid deformation of the piece, and maintained for a required period. In a further alternative, the pressure may be applied in peaks or cycles, or may be applied so that successively higher plateaus are achieved and maintained for a period of time. The curing cycle may vary and may last anywhere from 8 to 20 minutes or even longer, depending on the materials, i.e. composite materials to be used, the combination thereof and the desired characteristics of the hockey stick shaft. In addition to the application of pressure, the press and/or the tool may be heated or heat may otherwise be applied to the press and/or piece for the duration or for a part of the curing cycle. For example, the applied temperature may be increased up to and over 290° F., and maintained at that temperature for all or part of the curing cycle. One skilled in the art will recognize that the combination of air pressure, applied temperature and length of curing cycle may vary in order to achieve the required or desired result, or in accordance with the starting materials used or in accordance to both.

[0029] It will be understood that the application of pressure to the bladder will cause said bladder to expand outwardly, i.e. to deform somewhat, as the material to be used for the bladder may have some elasticity. The bladder, which through the application of air pressure, is made to expand outwardly (i.e. radially) pushes the prepregs outwardly against the walls (i.e. inside the cavity) of the tool. As may be understood, if sufficient pressure is applied to the bladder, the bladder may push the prepregs fully and completely outwardly against the walls of the tool, such that the prepregs may take on the inside shape of the tool, i.e. the outside dimensions of a finished hockey stick shaft will mirror the shape of the tool. The combination of sufficient air pressure, heat and time, may cause the prepregs to cure, i.e. to cause the resin impregnating the composite materials to cure, and to solidify in the shape of the tool. As may be understood, the inside of the shaft may remain, hollow. Thus, the resulting hockey stick shaft may have a cross-sectional shape which is thin-walled, hollow and has outside dimensions which are similar if not identical to the inside dimensions of the tool, i.e. the U-shaped cavities cut into the lower mold and the upper mold. It will be understood that the pressure that is applied, the length of time said pressure is applied and the temperature which the tool is subjected to will be sufficient to ensure that the hockey stick shaft is fully formed and results in a solid shaft suitable for its intended use.

[0030] Once the curing is complete, the tool is removed from the press, the top tool removed and the piece, now shaped like a hockey stick shaft is removed. Excess resin present may be removed from the-parting line, and the bladder may be removed from the inside of the shaft. Alternatively, the bladder may remain permanently inside the finished shaft. The shaft may then be trimmed to size.

[0031] It is understood that the present invention discloses a method of construction of a shaft, as well as the shaft itself constructed in accordance with said method. Thus, in accordance with a particular embodiment of the present invention, there is provided with a:

[0032] A method of construction of a shaft made of composite materials comprising the steps of: assembling a shaft portion from composite materials, wherein said composite materials are not cured, said shaft portion having opposed first and second extremities, said shaft portion comprising a hollow cavity disposed adjacent said first extremity, said hollow cavity being in fluid communication with said first extremity; assembling a tenon made of composite materials, wherein said composite materials are not cured, said tenon having a hollow first end sized and configured to be mated with said first extremity of said shaft portion; mating said hollow first end of said tenon with said first extremity of said shaft portion to form a joint; applying internal pressure to said joint so as to bond said tenon to said shaft portion through the co-curing of said composite materials so as to form a unitary joint.

[0033] In accordance with a further embodiment, there is provided for a:

[0034] method of construction of a shaft comprising the steps of: selecting a mandrel sized to correspond to the desired shape of the shaft, disposing a bladder over the outside of said mandrel, applying composite materials to the outside of said bladder, removing said mandrel from the inside of said bladder, leaving behind said bladder and said composite materials applied therearound, disposing said bladder and said composite materials in a mold, applying air pressure to said bladder such that said bladder expands, forcing said composite materials to conform to the shape of said mold, keeping said air pressure applied for a sufficient time so as to allow the curing of said composite materials to a rigid form.

DETAILED DESCRIPTION OF THE DRAWINGS

[0035] Other applications and advantages of the present invention may be made clear by the following detailed description of several embodiments of the invention. The description makes reference to the accompanying drawings in which:

[0036] FIG. 1 is an illustration of a composite hockey stick construction presently known in the prior art.

[0037] FIG. 2 is an illustration of an actual composite hockey stick construction presently known in the prior art.

[0038] FIG. 3 is a close-up of a tenon disposed inside a shaft showing the excess adhesive of prior art composite stick construction.

[0039] FIG. 4 illustrates the stress riser of known composite hockey stick construction in the prior art.

[0040] FIG. 5 is a section of a scarf joint under construction.

[0041] FIG. 6 is a section of a scarf joint under construction showing the mating of the tenon with the shaft.

[0042] FIG. 7 is a cross-section of a scarf joint being constructed showing the application of internal bladder pressure.

[0043] FIG. 8 is a perspective view of a mandrel having a bladder being fitted thereon.

[0044] FIG. 9 is a perspective view of a bladder fitted on a mandrel.

[0045] FIG. 10 is a perspective view of a strip of composite material applied on the outside of a bladder.

[0046] FIG. 11 is a perspective view of a mold with a piece about to be fitted therein.

[0047] FIG. 12 is a front elevation view of the mold having a piece disposed therein with an upper mold about to be disposed thereon.

[0048] FIG. 13 is a front and elevation view of the mold encasing the piece showing the application of internal pressure and the deformation of the piece to fit inside the mold cavity.

[0049] FIG. 14 is a top plan elevation view of the bottom cavity of the mold showing an alternative form of the cavity.

DESCRIPTION OF THE EMBODIMENTS

[0050] FIG. 1 is an illustration of a composite hockey stick construction presently known in the prior art. In particular, there is illustrated a blade 1 which is configured and disposed to be fitted into the hollow lower end 9 of a hockey stick shaft 3. The blade 1 comprises a palette 5 from which projects a hosel portion 6 which hosel portion has a narrower upper tenon 7. A shoulder portion 8 transitions the hosel 6 portion to the tenon 7. The hockey shaft 3, having a lower hollow portion 9, comprises thin-walled members 11, and the hollow portion 9 is configured and disposed to receive the tenon 7 therein. The thickness of the thin-walled portions 11 may be substantially the same as the size of the shoulder portion 8 such that once the tenon 7 is disposed inside the hollow portion 9, the outside surface 10 of hosel 6 may be flush with the outside wall 12 of shaft 3. As indicated by motion arrows 13 and 15, the blade 1 is to be displaced such that tenon 7 snugly fits inside hollow portion 9. An adhesive 14 such as a glue or other type of adhesive is disposed at the mouth end of hollow portion 9 such that the tenon 7 is firmly glued to the inside of the hollow portion once the blade 1 is moved therein. It is understood that the blade 1 and shaft 3 may each be moved in the direction of motion arrows 13 and 15 respectively, or that alternatively, only one of blade 1 or shaft 3 can be moved. Further, it is understood that adhesive 14, rather than being disposed at the mouth of hollow portion 9, may instead be coated to the surfaces of tenon 7 directly.

[0051] FIG. 2 illustrates an actual photo of the secondary bonding of a blade 1 to a shaft 3 as presently known in the prior art. As may be seen, the tenon is covered with adhesive and is shown as having been inserted inside the hollow cavity of the shaft.

[0052] FIG. 3 is a close-up of the end of the tenon as inserted inside the shaft and it shows the excess adhesive which may frequently be found in this type of joint. Said excess adhesive of course adds nothing but weight and therefore decreases the serviceability of the stick.

[0053] FIG. 4 illustrates a graph showing the location of a stress riser along the shaft constructed according to the teachings of the prior art, and shows where the weakness in a shaft may occur.

[0054] FIG. 5 illustrates an embodiment of the present invention, wherein there is shown the construction of a composite shaft and blade wherein there is no secondary bonding thereof. FIG. 5 therefore illustrates a lower portion of a hockey stick shaft 25 under construction, comprising a hosel 26 and a shaft 27. Hosel 26 is illustrated as coming to a point 35 for further incorporation into a blade (not shown). Hosel 26 is illustrated as comprising a hollow core 28 and exterior thin walls 30 surrounding hollow core 28. Further, hosel 26 is shown as having an open mouth 37 disposed at the top end thereof. Shaft 27 is illustrated as having a hollow portion 32 at its lower end, which hollow portion 32 is defined by thin walls 39.

[0055] Thin walls 39 of shaft 27 and thin walls 30 of hosel 26 are made of prepregs, which may be strips of composite materials which are pre-impregnated with resins such as epoxy resins, thermosetting resins or any other resins. The composite materials themselves may be carbon fibres, Kevlar™, fibreglass, viscoelastic film adhesives and so on. Thus, thin walls 30 and 39 are constructed from a series of layers of prepregs which have been previously applied (not shown). Subsequent to the application of the prepregs, the curing thereof is not completed, such that the thin walls 30 and 39 are still malleable, while at the same time retaining some structural shape. Thus, as may be understood, thin walls 30 and 39 are still soft, yet firm enough for handling and displacement.

[0056] Subsequent to the initial construction of hosel 26 and shaft 27, the open mouth 37 of hosel 26 and open mouth 41 of shaft 27 are disposed in close proximity 29 as illustrated in FIG. 5. A bladder 35 is disposed within hollow portion 28 and hollow portion 32 through any known means, such as, for example, through manual or mechanical application, or through the blowing of air therein such that it fills the cavities of hollow portions 28 and 32. As illustrated, bladder 38 is closed at one end and open for the introduction therein of fluids such as air at the other end (not shown). As illustrated, bladder 35 is shown as being spaced apart from the walls of hollow portions 28 and 32 for illustrative purposes only but it is understood that either through its introduction therein, or through the blowing of air inside bladder 35, the walls of bladder 35 may abut and push against the walls of cavities 28 and 32.

[0057] FIG. 6 illustrates the next step in the construction of the one-piece shaft construction. As shown, hosel 26 and shaft 27 are being displaced towards each other in the direction of motion arrows 31 and 33, causing a portion 43 of thin wall 30 of hosel 26 to collapse inwardly such that the thin wall 39 of shaft 27 can be disposed on the outside thereof. Such a joint may be known as a scarf joint. The collapse of portion 43 of thin wall 30 of hosel 26 is made possible by the fact that the prepregs used to construct thin wall 30 are not fully cured and therefore are soft and malleable to the extent necessary to allow sufficient deformation thereof.

[0058] FIG. 7 illustrates the next step in the construction of the one-piece shaft construction. As illustrated, hosel 26 and shaft 27 have been mated by the overlap of portion 43 of thin wall 30 of hosel 26 with thin wall 39 of shaft 27 which has produced an enlarged portion 47 at the intersection 29 of the hosel 26 and shaft 27. As may be seen, due to the increase of the thickness of the wall at section 29, walls 47 portions are thicker than thin walls 30 and 39 immediately adjacent thereto. Once the mating is complete, air or other fluid can be introduced inside bladder 35, causing bladder 35 to expand outwardly in the direction of motion arrows 45. As illustrated, bladder 35 is shown as being spaced apart from the walls of the hosel and of the shaft for illustration purposes only. It is understood that once a sufficient amount of air is introduced inside bladder 35, same will expand to push up and out against the inside walls of hosel 26 and shaft 35.

[0059] It is understood that the expansion of bladder 35 need be done in such a manner that the outside walls 47 and 49 of hosel 26 and shaft 27 respectively are made to push out against a form, mold or die. It will be understood that the absence of this form will simply mean that the bladder will expand until it bursts. Although not shown, the hosel 26/shaft 27 combination as illustrated in FIG. 7 may be, prior to the expansion of bladder 35 (complete expansion) to be placed in a mold, cavity or other form which will enable the inner pressure applied by bladder 35 to create the final form of the hosel 26 and shaft 27. In particular, overlap of portion 29 is subjected to the outward pressure 45 of bladder 35 so as to create the co-curing of the prepregs of the thin wall 30 of hosel 26 with the prepregs of thin wall 39 of shaft 27. Heat may also be applied to cure, or assist in the curing of the prepregs.

[0060] FIG. 8 illustrates a further embodiment of the present invention, wherein a mandrel 50 is illustrated immediately prior to the fitting thereon of a bladder 52 in the direction of motion arrows 54. As may be seen, mandrel 50 is generally cylindrical in shape, having an elongated form which may be sized so as to be longer (i.e. slightly longer) than the desired length of the finished shaft. Mandrel 50 is shown as being solid but it is understood that it can, if required or desired, be thin-walled and/or hollow. Bladder 52 is illustrated as being constructed of a thin-walled material, such as nylon, rubber, silicon or latex, sized and configured to fit over mandrel 50 from one end thereof to the other.

[0061] FIG. 9 illustrates a mandrel 50 having the bladder 52 disposed thereon. As may be seen, bladder 52 comprises a closed end 56 and an open end 58. Open end 58 may be fitted with an adapter (not shown) for the introduction of air therein.

[0062] FIG. 10 illustrates a further step in the construction of a composite shaft. As may be seen, mandrel 50 has been fitted thereon with a bladder 52. A strip of prepreg 60 is shown as having been applied on the outside of bladder 52, from one end of the mandrel 50 to the other end thereof. As illustrated, prepreg 60 is shown as being a relatively thin elongated strip of composite material which has been wound about at an angle vis-à-vis the longitudinal axis of mandrel 50. For illustration purposes, it will be understood that a number of further strips of prepregs 60 will be necessary to fully cover the outside of the bladder. It will be further understood that further prepregs 60 may be applied in a similar manner to that shown in FIG. 10, i.e. at the same angle in relation to the longitudinal axis, or alternatively, at a different angle. For example, one or more additional layer of prepregs might be added so that the orientation of the prepregs may be disposed at 90° to the orientation of the prepreg 60 illustrated in FIG. 10. In addition, prepreg strips may be applied longitudinally, i.e. from one extremity of mandrel 50 to the other without any twisting thereabout. Further, prepregs can be applied in small strips which simply circle once about the mandrel 50. It is further understood that prepregs can be applied in any number of combinations or variations as described above and that a number of layers of prepregs can be applied, each layer being similar and/or different in its application than that illustrated in FIG. 10.

[0063] The prepregs 60 may be applied either manually or mechanically or a combination of both. As they are applied, a small amount of pressure is applied thereon such that the prepregs adhere to the underlying surface, however this pressure may not be sufficient to cure, i.e. completely cure the prepregs to their final form.

[0064] Once the prepregs 60 have been applied to the outside of the bladder 52, mandrel 50 is removed in the direction of motion arrow 62. As may be understood, mandrel 50 may be tightly disposed within bladder 52 and may require some twisting and/or pulling to dislodge same from within bladder 52.

[0065] FIG. 11 is a perspective view of the piece 64 about to be inserted into a tool 69. Tool 69 is illustrated as comprising a body 70 which may be made of any suitable material, for tool or dies, such as steel, brass, aluminum or ceramic. The tool comprises a cavity 71 which is shown for illustration purposes only as being short. It is understood, however, that said cavity 71 is to be used to shape the shaft of a hockey stick, and can therefore be up to 60 or 72 inches long. Cavity 71 comprises four surfaces, namely bottom surface 72, opposed-side surfaces 74 and rear surface 76. It is understood that the configuration and disposition of cavity 71 is to be similar to the outside final shape of the desired hockey stick shaft. Thus, if it is required or desired that the outside surfaces of the finished hockey stick be flat (i.e. without a curve), bottom surface 72, opposed-side surfaces 74 and rear surface 76 will be of a correspondingly flat shape (i.e. without any or substantially any curve). It is also understood that opposed-side surfaces 74 may be parallel to each other, but if the final shape of the hockey stick shaft is to be other than having parallel-side surfaces, opposed-side surfaces 74 may not be parallel to each other but may instead converge to a point, either throughout the length of the cavity 71 or alternatively, the convergence may begin at or near one extremity of cavity 71. Further, cavity 71 may comprise round and/or beveled corners where, for example, bottom surface 72 intersects side surface 74. In addition, surfaces 72, 74 and 76 may be concave or convex.

[0066] Piece 60 comprises, as described above, a bladder 52 onto which have been rolled or applied prepregs 60 such that the outside surface of bladder 52 is completely covered therewith.

[0067] The dimension (i.e. cross-sectional dimension of cavity 71) is related to the cross-sectional dimension of piece 64. As may be understood, piece 64 is to fit inside cavity 71, and once the application of air pressure to the inside of the bladder is effected, the deformation of piece 64 will occur such that all (substantially all of the volume of cavity 71) is to be filled with the(a?) piece. Thus, since the prepregs have a limited linear elasticity, but can however be deformed to fit a shape, the circumference of the piece 64 is to be similar, i.e. slightly smaller than the circumference of the cross-sectional area of cavity 71 as illustrated in FIG. 12. As may be understood, a slight amount of deformation will be required in order to fit piece 64 inside cavity 71, however said deformation may be accomplished due to the fact that the prepregs are not fully cured and are therefore still malleable while retaining some stiffness.

[0068] FIG. 12 illustrates a front end elevation view of the tool 69 of FIG. 11. As may be seen, piece 64 has been inserted inside cavity 71 of tool 69. As illustrated, parts of the outside surface of prepregs 60 may be in contact with bottom surface 72, opposed-side surfaces 74 and rear surface 76 (not shown). As may be seen, cavity 71 is configured and disposed so that approximately half of piece 64 fits therein. Further, top piece 80, a substantial mirror image of piece 69, is shown as being displaced downwardly so as to meet tool 69 and so as to encase piece 64 therein. Although top tool 80 and tool 69 are shown as being substantially similar, it is understood that cavity 71 may, for example, be configured and disposed such that it fits more or less than half of piece 64 therein. In a further embodiment, it is understood that cavity 71 may, for example, be able to fit the whole of piece 64 therein, and upper tool 80 would in this case simply be a flat lid which serves to provide a top surface without any side surfaces.

[0069] FIG. 13 illustrates the next step in the construction of the one-piece shaft, wherein the upper tool 80 has closed down on top of tool 69, fully encasing piece 64 within cavities 71 and 79. As illustrated, piece 64 is shown as being in the process of being inflated outwardly by the air pressure being applied inside bladder 52 such that it is deforming in the direction of motion arrows 82. Although shown not fully occupying the whole of the volume of cavities 71 and 79, through the sufficient application of air pressure, piece 64 will eventually deform fully so that it takes the shape of opposed-side surfaces 74 and 75, as well as bottom surface 72 and top surface 73.

[0070] FIG. 14 illustrates a top plan view of an alternative tool 80 similar to that shown in FIG. 11. Cavity 84 is shown as having substantially the shape of a hockey stick shaft, wherein the surfaces of bottom-most portion 86 are shown as being angled towards each other.

Claims

1. A method of construction of a shaft made of composite materials comprising the steps of:

a. assembling a shaft portion from composite materials, wherein said composite materials are not cured, said shaft portion having opposed first and second extremities, said shaft portion comprising a hollow cavity disposed adjacent said first extremity, said hollow cavity being in fluid communication with said first extremity;

b. assembling a tenon made of composite materials, wherein said composite materials are not cured, said tenon having a hollow first end sized and configured to be mated with said first extremity of said shaft portion;

c. mating said hollow first end of said tenon with said first extremity of said shaft portion to form a joint;

d. applying internal pressure to said joint so as to bond said tenon to said shaft portion through the co-curing of said composite materials so as to form a unitary joint.

2. The method of construction of claim 1 wherein the application of pressure is effected through the introduction of a bladder inside said hollow cavity and said hollow first end prior to the mating thereof, said bladder being inflated such that it pressures the curing together of the composite material of said tenon and of said shaft portion.

3. The method of construction of claim 2 wherein prior to the application of said internal pressure to said bladder, said mated shaft portion and tenon are disposed inside a mold.

4. The method of construction of claim 1 wherein the composite materials of said shaft portion and of said tenon are not subjected to pressure prior to said mating.

5. The method of construction of claim 1 wherein said composite materials of said shaft portion and of said tenon are uncured prior to said mating.

6. The method of construction of claim 1 wherein said composite materials of said shaft portion and of said tenon are subjected to some pressure prior to mating.

7. The method of construction of claim 1 wherein the mating occurs through the insertion of said hollow first end of said tenon inside said first extremity of said shaft portion.

8. The method of construction of claim 1 wherein the mating occurs through the insertion of said first extremity of said shaft portion inside said first end of said tenon.

9. The method of construction of claim 2 wherein said bladder is internally disposed substantially along the whole length of said shaft and of said tenon.

10. The method of construction of claim 1 wherein said shaft is a shaft suitable for use with sporting equipment.

11. The method of construction of claim 10 wherein said shaft is a hockey stick shaft.

12. A method of construction of a shaft comprising the steps of:

a. selecting a mandrel sized to correspond to the desired shape of the shaft;

b. disposing a bladder over the outside of said mandrel;

c. applying composite materials to the outside of said bladder;

d. removing said mandrel from the inside of said bladder, leaving behind said bladder and said composite materials applied therearound;

e. disposing said bladder and said composite materials in a mold;

f. applying air pressure to said bladder such that said bladder expands, forcing said composite materials to conform to the shape of said mold;

g. keeping said air pressure applied for a sufficient time so as to allow the curing of said composite materials to a rigid form.

13. The method of construction of claim 12 wherein said mold comprises a lower mold portion and an upper mold portion, wherein said bladder and said composite materials are disposed in said lower mold portion prior to the application of said air pressure, said upper mold portion being disposed over said lower mold portion so as to encase said bladder in said composite materials prior to the application of said air pressure to said bladder.

14. The method of construction of claim 12 wherein said mold is configured and sized so as to impart to said composite materials the shape of a hockey stick shaft.

15. A method of construction of claim 12 wherein the air pressure applied is in the range of 0 to 200 P.S.I.

16. The method of construction of claim 15 wherein the air pressure is applied in a smooth, continuous gradient up to its required pressure.

17. The method of construction of claim 15 wherein the air pressure is applied in an initial rapid burst up to the desired pressure and then maintained for the duration of the curing.

18. The method of construction of claim 15 wherein heat is applied to the mold during the curing of said composite materials.

19. The method of construction of claim 15 wherein the mold is heated prior to the introduction of said bladder and said composite materials and wherein the heat of the mold is increased during said curing.

20. The method of construction of claim 15 wherein said bladder is made from a group of materials comprising nylon, silicone, rubber and latex.

21. The method of construction of claim 15 wherein said composite materials are selected from a group comprising carbon fibers, fiberglass, Kevlar™ and viscoelastic films.

22. The method of construction of claim 15 wherein the mold comprises a mold cavity which cavity comprises opposed, spaced apart, top and bottom surfaces, and opposed left and right surfaces spacing apart said top and bottom surfaces.

23. The method of construction of claim 22 wherein said top and bottom surfaces are flat.

24. The method of construction of claim 22 wherein said top and bottom surfaces are parallel to each other.

25. The method of construction of claim 22 wherein one or more of said top surface, bottom surface, left surface and right surface is curved.

26. The method of construction of claim 15 wherein said left and right surfaces are parallel to each other for a portion of the mold cavity and converge to a narrower point adjacent to one extremity thereof.

27. A shaft constructed using the method of construction of claim 15.

28. The shaft of claim 27 wherein said shaft is a hockey stick shaft.