Abstract:
A sports shaft having an elongated body having a perimeter defined by a plurality of main walls with adjacent ones of the main walls being interconnected through a corresponding one of a plurality of edge walls, the edge walls being spaced apart around the perimeter. A respective bumper extends along at least part of length of at least one of the edge walls. The main and edge walls without the respective bumper have a first stiffness along a longitudinal direction of the shaft, and a combination of the respective bumper with the at least one of the edge walls has a stiffness along the longitudinal direction greater than the first stiffness. A method of making a sports shaft is also discussed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from U.S. provisional application No. 62/322,342 filed Apr. 14, 2016, the entire contents of which are incorporated by reference herein. 
     
    
     TECHNICAL FIELD 
       [0002]    The application relates generally to sports equipment and, more particularly, to sports shaft for elongated sports equipment such as hockey sticks. 
       BACKGROUND OF THE ART 
       [0003]    Sports equipment having an elongated shaft, such as hockey sticks, must typically be able to withstand a large number of impacts, particularly along the edges of the shaft which are typically more susceptible to damage during play. 
         [0004]    The shaft is additionally subjected to significant stresses due to manipulation during play, including bending stresses, which can lead to damage of some known edge protectors. 
       SUMMARY 
       [0005]    In one aspect, there is provided a sports shaft comprising: an elongated body having a perimeter defined by a plurality of main walls with adjacent ones of the main walls being interconnected through a corresponding one of a plurality of edge walls, the edge walls being spaced apart around the perimeter; a respective bumper extending along at least part of length of at least one of the edge walls; wherein the main and edge walls without the respective bumper have a first stiffness along a longitudinal direction of the shaft; and wherein a combination of the respective bumper with the at least one of the edge walls has a second stiffness along the longitudinal direction which is greater than the first stiffness. 
         [0006]    In another aspect, there is provided a method of making a sports shaft, the method comprising: forming at least one elongated bumper in a cured state; surrounding an expandable mandrel with layers of uncured material; placing the surrounded mandrel in a female mold with the at least one elongated bumper extending along a respective edge wall of the shaft; and curing the uncured material by heating and pressing the uncured material against mold surfaces of the female mold with the mandrel to produce the sports shaft. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0007]    Reference is now made to the accompanying figures in which: 
           [0008]      FIG. 1  is a schematic side view of part of a hockey stick according to a particular embodiment; 
           [0009]      FIG. 2  is a schematic cross-sectional view of a shaft of the hockey stick of  FIG. 1 , according to a particular embodiment; 
           [0010]      FIG. 3  is a schematic, broken side view of a bumper of the shaft of the hockey stick of  FIG. 1 , according to another particular embodiment; 
           [0011]      FIG. 4  is a schematic cross-sectional view of the bumper of  FIG. 3 , taken along lines  4 - 4 ; 
           [0012]      FIG. 5  is a schematic cross-sectional view of the bumper of  FIG. 3 , taken along lines  5 - 5 ; 
           [0013]      FIG. 6  is a schematic cross-sectional view of the bumper of  FIG. 3 , taken along lines  6 - 6 ; 
           [0014]      FIG. 7  is a schematic cross-sectional view of a shaft of the hockey stick of  FIG. 1 , according to another particular embodiment; 
           [0015]      FIG. 8  is a schematic tridimensional view of a part of the shaft of the hockey stick of  FIG. 1 , according to another particular embodiment; 
           [0016]      FIG. 9  is a schematic tridimensional view of part of the shaft of the hockey stick of  FIG. 1 , showing bumpers according to various particular embodiments; and 
           [0017]      FIG. 10  is a tridimensional view of a step of a molding process of the shaft of the hockey stick of  FIG. 1 , according to a particular embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Referring to  FIG. 1 , part of an elongated sports equipment including a shaft is shown, which in this embodiment is a hockey stick  10  generally including a blade  12  having the shaft  14  extending from one end thereof. It is understood that alternately the elongated sports equipment may be any suitable type of equipment having a shaft, including, but not limited to, ice hockey stick, field hockey stick, floor, dek or street hockey stick, lacrosse stick, ringuette stick, etc. 
         [0019]    Referring to  FIG. 2 , the shaft  14  is generally defined by a plurality of interconnected elongated main walls  16 ; in the particular embodiments shown and described therein, two pairs of parallel or substantially parallel main walls  16  are provided, with the two pairs extending perpendicularly or substantially perpendicularly from each other, so that the shaft  14  has a rectangular cross-sectional shape. 
         [0020]    The shaft  14  is generally hollow, and the adjacent main walls  16  are interconnected by elongated edge walls  20 , which may have a smaller width than the main walls  16 , and are spaced around the perimeter of the shaft  14 . In the embodiment shown, the edge walls  20  each define a flat or slightly convex outer surface  22  extending at approximately 45 degrees from each of the two interconnected main walls  16 , and connected to each main wall  16  by a respective elongated shoulder  24 , such that each edge wall  20  defines a recess or groove in the outer perimeter of the shaft  14 ; other configurations are possible, some of which will be further described below. 
         [0021]    Each edge wall  20  includes a respective elongated stiffening bumper  26  which extends along at least part of the length of the edge wall  20  and of the shaft  14  (only one bumper  26  being shown in  FIG. 1 ). In the embodiment shown, each edge wall  20  is covered, in whole or in part, by the respective bumper  26 , and an outer surface  28  of the bumpers  26  extends continuously with the outer surface  18  of the adjacent main walls  16 . It is understood that alternately, the bumper  26  may extend within the edge wall  20 , whether completely embedded therein so that the edge wall  20  defines outer and inner surfaces with the bumper  26  extending therebetween, or located such that an inner surface of the bumper  26  is exposed in the internal cavity of the hollow shaft  14 . 
         [0022]    Referring to  FIGS. 1 and 3-6 , in a particular embodiment, the cross-section of each bumper  26  varies along the longitudinal direction L, i.e. along the length of the shaft  14 . In the embodiment shown, the cross-section of the bumper  26  varies both in width w and in thickness t, which are both greater along an intermediate longitudinal portion  30  ( FIG. 5 ) of the bumper  26  than at its extremities  32  ( FIG. 6 ). Alternately, the bumper  26  may have a constant width w and/or thickness t along its length. 
         [0023]    Although the main walls  16  are shown with a flat outer surface  18 , and with a clear transition between the main walls  16  and the edge walls  20 , it is understood that alternately the main walls  16  and/or edge walls  20  may have a concave or convex outer surface  18 . It is understood that other cross-sectional shapes and/or a different number of main walls are also possible, including, but not limited to, non-parallel and non-perpendicular walls, and/or semi-circular, hexagonal and octagonal cross-sectional shapes. 
         [0024]    Although not shown, one or more additional layers of material may be applied over the main walls  16  and bumpers  26 , for example a cosmetic layer of paint and/or decals providing a desired visual aspect for the shaft  14 , which may be overlaid by a transparent coating, for example to provide wear protection. Accordingly, the bumpers  26  may not be visible in use even when they are engaged to an outer surface of the edge walls  20 . 
         [0025]    The combination of each bumper  26  with its associated edge wall  20  has a stiffness along the longitudinal direction L of the shaft  14  which is greater than that of the main and edge walls  16 ,  20  of the shaft  14 . Although the bumper  26  may be made of material less stiff than that of the main and edge walls  16 ,  20 , in a particular embodiment, each bumper  26  alone has a stiffness along the longitudinal direction L of the shaft  14  which is greater than that of the main and edge walls  16 ,  20  of the shaft  14 . 
         [0026]    The bumpers  26  form a reinforcement structure (e.g. external reinforcement structure in the embodiment shown) for the shaft  14 , providing reinforcement at least along the longitudinal direction L. Accordingly, the bumpers  26  add protection to the edge walls  20  of the shaft  14 , while also contributing to adding stiffness to the shaft  14  along these edge walls  20 , which in particular embodiment allows to improve the performance of the stick  10 . 
         [0027]    In a particular embodiment, the presence of the bumpers  26  provides for an increased resistance in bending of the shaft  14 , as compared with a similar shaft without bumpers. In a particular embodiment, the bumpers  26  have a higher impact toughness than the main and edge walls  16 ,  20  of the shaft  14 . 
         [0028]    In a particular embodiment, the difference in stiffness between the bumpers  26  and the main and edge walls  16 ,  20  is obtained by having the bumpers  26  made from a different material than that of the main and edge walls  16 ,  20 . The material of the bumpers  26  may also have a greater hardness than that of the material of the main and edge walls  16 ,  20 . 
         [0029]    In a particular embodiment, the bumpers  26  and walls  16 ,  20  are all made of composite material including reinforcing fibers, with the bumpers  26  including a greater proportion of fibers oriented along the longitudinal direction L than the walls  16 ,  20 . In one example of shaft configuration, the walls  16 ,  20  are made from laminated layers of pre-preg materials having reinforcing fibers extending in multiple directions, for example non-woven fibers, or woven fibers extending non-parallel to the longitudinal direction L, with optionally having some of the fibers extending along the longitudinal direction L, and the bumpers  26  are made from fiber-reinforced material where all of the fibers extend along the longitudinal direction L. Other configurations are also possible. 
         [0030]    The bumpers  26  and walls  16 ,  20  made of composite material with differently oriented fibers may be made of the same composite material, or of different composite materials. For example, in a particular embodiment, the walls  16 ,  20  are made of a carbon fiber/epoxy composite material, while the bumpers  26  are made of an aramid fiber/epoxy composite material. Any other suitable types of fibers may be used in the bumpers  26  including, but not limited to, carbon and glass fibers, in combination with walls  16 ,  20  including reinforcing fibers or with walls  16 ,  20  made of any other suitable type of material. 
         [0031]    In a particular embodiment, applicable but not limited to carbon fibers in the walls  16 ,  20  and aramid fibers in the bumpers  26 , the fibers of the bumper  26  have a higher elongation at failure than the fibers of the walls  16 ,  20 ; the fibers of the bumper  26  are more ductile and accordingly have a higher impact toughness than the fibers of the walls  16 ,  20 . When fibers made of different materials are used in the bumpers  26  and walls  16 ,  20 , the fibers in the bumpers  26  and walls  16 ,  20  may have a similar orientation, providing the difference in material provides sufficient increased stiffness for the edge walls  20  containing the bumpers  26 . 
         [0032]    Other suitable materials for the bumpers  26  include any appropriate material sufficiently rigid such as to be amorphous and not flow under impact suffered during normal use of the shaft  14 . Examples of suitable materials include, but are not limited to, metal such as aluminium, bamboo or other suitable wood, suitable plastics, suitable thermoplastic fibers such as polypropylene fiber (e.g. Innegra™) and polyethylene fiber (e.g. Dyneema™). In a particular embodiment, the bumpers  26  are made of non-elastomeric material. 
         [0033]    Referring to  FIG. 7 , an alternate configuration for the shaft  14  is shown. In this embodiment, the main walls  116  and edge walls  120  are connected in a continuous manner so as to cooperate to define a continuous cross-sectional shape, such as the oval cross-sectional shape shown. In this embodiment, bumpers  126  are received on the outer surface of the edge walls  120 , and the outer surface  128  of the bumpers  126  extends continuously or substantially continuously with the outer surface  118  of the adjacent main walls  116 , so as to form a rectangular or substantially rectangular outer cross-sectional shape for the shaft  14 . The walls  116 ,  120  and bumpers  126  may have similar materials and properties as the respective walls  16 ,  20  and bumpers  26  described above. 
         [0034]    Referring to  FIG. 8 , another alternate configuration for the shaft  14  is shown. In this embodiment, the outer surface of the bumpers  226  is non-continuous with the outer surface  218  of the adjacent main walls  216 ; the bumpers  226  protrude outwardly from the outer surface  218  of the adjacent main walls  216 , such that each bumper  226  forms an outward bulge with respect to a cross-sectional shaft area defined by the outer surface  218  of the main walls  216 . The shoulders are omitted from the edge wall  220 , such that the outer surface  222  of the edge wall  220  is directly connected to the outer surface  218  of the main wall  216 . The walls  216 ,  220  and bumpers  226  may have similar materials and properties as the respective walls  16 ,  20  and bumpers  26  described above. 
         [0035]    It is understood that any configuration of edge walls  20 ,  120 ,  220  of  FIGS. 2, 7 and 8  may be combined with any configuration of bumper  26 ,  126 ,  226  of  FIGS. 2, 7 and 8 . 
         [0036]    In the embodiments shown above, the bumper  26 ,  126 ,  226  has a crescent-shaped cross-section; however, it is understood that any other suitable cross-section shape may be used.  FIG. 9  shows examples of suitable cross-sectional shapes. The different bumper shapes are shown as applied to a same shaft; it is understood that all the bumpers of the shaft may have a similar shape, and that alternately, two or more of the bumpers of the same shaft may have different shapes from one another (for example, the shaft may include two pairs of similar bumpers with the bumpers of different pairs having different shapes). 
         [0037]    In one embodiment, the edge wall  320   a  is defined as a concave arc extending around an included angle of more than 180 degrees. The bumper  326   a  has a circular, hollow cross-section and is received in the groove defined by the concave edge wall  320   a . Alternately, the bumper  326   a  may be a solid bumper, i.e. without the hollow center shown. 
         [0038]    In another embodiment, the edge wall  320   b  is defined as a convex arc connected to each adjacent main wall  316  by a shoulder  324   b . The bumper  326   b  has a c-shaped cross-section of constant thickness and is received against the convex arc of the edge wall  320   b , in abutment with and between the shoulders  324   b.    
         [0039]    In another embodiment, the edge wall  320   c  is defined as a convex arc directly connected to the adjacent main walls  316  to form a continuous surface therewith, i.e. without shoulders therebetween. The bumper  326   c  has a c-shaped cross-section and is received against the convex arc of the edge wall  320   c . The bumper  326   c  has tapered ends at the junction with the adjacent main walls  316  such that the outer surface of the bumper  326   c  is continuous with the outer surface of the main walls  316 . 
         [0040]    In another embodiment, the edge wall  320   d  is defined as a concave arc extending around an included angle of less than 180 degrees. The bumper  326   d  has a hollow, leaf-shaped cross-section (elliptical shape with pointed ends) and is received in the groove defined by the concave edge wall  320   d . Alternately, the bumper  326   d  may be a solid bumper, i.e. without the hollow center shown. 
         [0041]    All the bumpers  326   a - d  of  FIG. 9  are shown as having an outer surface which extends continuously with the outer surface  318  of the adjacent main walls  316 . Alternately, any of the bumpers  326   a - d  shown may have an outer surface which is non-continuous with the outer surface  318  of the adjacent main walls  316 ; the bumper  326   a - d  may protrude outwardly from the outer surface  318  of the adjacent main walls  316  such as to form an outward bulge with respect to the cross-sectional shaft area defined by the outer surface  318  of the main walls  316 . The walls  316 ,  320  and bumpers  326   a - d  may have similar materials and properties as the respective walls  16 ,  20  and bumpers  26  described above. 
         [0042]    It is understood that any other suitable solid or hollow cross-sectional shape can alternately be used for the bumpers. Each edge wall may have an outer surface defined by a single planar or curved surface, or by a plurality of interconnected planar or curved surfaces. 
         [0043]    Although the shaft  14  has been shown with a bumper covering each of its edge walls, it is understood that alternately, only one or some of the edge walls may be provided with (e.g. covered with) a respective bumper. 
         [0044]    In a particular embodiment, the bumpers  26 ,  126 ,  226 ,  326   a - d  are formed separately from the main and edge walls of the shaft  14  and, if made from a material necessitating curing, cured before being assembled to the walls of the shaft. In a particular embodiment where the walls of the shaft are made from a material necessitating curing, the cured bumpers are positioned on the uncured walls, and the walls are cured and bonded to the bumpers during curing, in a co-curing operation. Alternately, the walls of the shaft and the bumpers may be separately cured, and then bonded together in a subsequent operation. 
         [0045]    In a particular embodiment where the bumpers are in composite material, the bumpers are made by pultrusion with the reinforcing fibers all oriented longitudinally, and optionally machined after pultrusion if a variable width and/or thickness is required along the length of the bumpers, such as shown for example in  FIGS. 3-6 . Alternately, the bumpers may be molded, directly to the desired shape or into an intermediate shape which may be machined as required. 
         [0046]    Referring to  FIG. 10 , in a particular embodiment the shaft  14  is formed by a compression or bladder molding method. Layers of uncured pre-preg material  34  are assembled around an expandable mandrel  36  to define the shaft  14 . The mandrel  36  is placed in a female mold  38  (only part of which is shown), with the cured bumpers  26 ,  126 ,  226 ,  326   a - d  being each disposed over the location of the respective edge wall. Adhesive may be provided between the bumpers and uncured material  34  of the shaft, and/or lightweight scrim may be used to hold the number in place on the shaft pre-form defined by the uncured material. Alternately, the bumpers could be disposed over their respective location by being retained in the mold cavities. 
         [0047]    If the bumpers are intended to be contained within the edge wall, one or more additional layer(s) of pre-preg material  34  may be wrapped around the bumpers and shaft after the bumpers are disposed over the location of the respective edge wall. 
         [0048]    The mold  38  is closed, and the expandable mandrel  36  is expanded while heating the assembly to press the uncured material  34  against the mold surfaces  40  (only partially shown) of the female mold  38  to cure the material of the walls of the shaft  14 . The pressure of the uncured material against the mold surfaces  40  forms a close contact between the bumpers  26 ,  126 ,  226 ,  326   a - d  and the material of the walls; in some embodiments, the bumpers are partially or completely embedded in the walls. The bumpers, for example located intermediate the mold surface  40  and the material of the shaft  14 , shape the edge walls, with the pressure of the expandable mandrel  36  pressing the material  34  against and around the bumpers. 
         [0049]    In a particular embodiment, the expandable mandrel  36  is a bladder, which is expanded to press the material  34  against the mold surfaces  40  by inflation. In another embodiment, the expandable mandrel  36  is made of thermally expandable material, which is thermally expanded to press the material  34  against the mold surfaces  40 . Suitable thermally expandable materials include, but are not limited to, silicone. 
         [0050]    In a particular embodiment, the presence of the bumper(s) advantageously allows to modify the stiffness properties of the overall shaft by changing the way the material is distributed around the perimeter of the shaft. The added stiffness in the “corners” (edge walls) provide for a rigidity adjustment, increase of impact toughness and/or increase in bending strength as compared to a similar shaft without bumpers. 
         [0051]    The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.