Abstract:
A self-centering skate holder for clamping a skate blade from above and below which maintains the blade at a predetermined height and parallelism. A handle is connected with a cable which is taut and extends around the circumference of the upstanding vertical member. The movements of the cable activate cam levers which rotate cams that move a pair of jaws towards or away from each other. The simultaneous movements of the cams ensure that the jaws move in unison and through a similar distance allowing a skate blade of any thickness to be clamped along the desired centerline. In an alternative mechanism, a tie bar extends between the jaws and is operated by a cam to induce equal and opposite movement of the jaws.

Description:
[0001]     This application is a continuation-in-part of U.S. patent application Ser. No. 10/735,896 filed on Dec. 16, 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to skate holders for use with skate sharpening machines.  
       DESCRIPTION OF THE PRIOR ART  
       [0003]     Skates used in activities such as hockey, figure skating, speed skating and for leisure include a boot and a blade. The blade is attached to the bottom of the boot and is used to ‘dig into’ an ice surface allowing the skater to glide along the ice due to the opposing force imparted on the skater when pushing against the ice surface. To effectively grip the ice surface, the blade includes a concave surface at its lowermost edge. This concave surface, commonly known as a ‘hollow ground’, produces two parallel edges opposed about the centreline of the hollow ground. Through repeated contact with the ice surface, the edges are worn down due to friction with the ice surface and periodically need to be sharpened.  
         [0004]     Sharpening a skate blade involves restoring the sharp edges of the skate blade by bringing the dull edges into engagement with the convex radius of the face of a grinding wheel and applying pressure. This allows the grinding wheel to grind the blade in a manner that restores the previously achieved sharp edges with two parallel edges. A proper sharpening requires that the centreline of the hollow grind be in a similar plane as the centreline of the convex radius of the grinding wheel. This is achieved by maintaining the skate blade in the proper orientation and at the proper height.  
         [0005]     Typically, a skate sharpening grinding wheel is horizontally oriented so that its axis of rotation is perpendicular to the table on which it is mounted. With the grinding wheel parallel to the table, the skate blade must be held with its outwardly facing edges parallel to the grinding table and the concave surface of the blade held at an identical level as the convex radius of the grinding wheel. To maintain this orientation, a holder is required which typically includes a clamping mechanism to maintain the skate in the proper position for the duration of the sharpening procedure.  
         [0006]     A skate holder with a clamping mechanism is shown in a U.S. Pat. No. 4,078,337 to Chiasson et al. The skate blade is placed with one outwardly facing surface against a stationary jaw. The opposing jaw is lowered against the other outwardly facing surface and tightened to secure the skate in place. The stationary jaw is positioned so that a particular blade in the proper alignment with the convex radius of the grinding wheel. By securing the skate blade between a clamping jaw and a stationary jaw, any blade that is clamped would be held at a similar level. Since the thickness of a skate blade may vary between different skate models and different skate types, this type of clamping mechanism does not ensure that the centrelines of the hollow ground and convex outer radius of the grinding wheel are aligned properly. A misaligned blade will of course impart an uneven sharpening due to the off-center grinding from the grinding wheel.  
         [0007]     To ensure the centrelines of the hollow grind and convex outer radius of the grinding wheel are properly aligned, self-centering skate holders have been developed. To achieve self-centering, the clamping mechanism allows both jaws to approach the blade from their respective sides. By moving identical distances during the clamping operation, no matter the thickness of the blade, the centerline will be properly aligned. A self-centering skate holder is shown in a U.S. Pat. No. 4,055,026 to Zwicker and similarly a U.S. Pat. No. 6,422,934 to Blach et al. The clamping arms in these designs are pivoted about an axis located a distance behind the point of clamping and consequently behind the boot and the blade. This arrangement creates a large area for the skate to be placed. While this design achieves self-centering, the location of the pivot axis renders a large and bulky apparatus. To achieve a proficient sharpening, it is beneficial for the user to have full control of the skate holder. The user must guide the holder towards the grinding wheel, therefore a large and bulky design is not desired.  
         [0008]     It is therefore an object of the present invention to obviate or mitigate at least one of the above mentioned disadvantages.  
       SUMMARY OF THE INVENTION  
       [0009]     In one aspect a self-centering skate holder is provided comprising a base, a mounting plate secured to said base and having an elongated slot therein to receive a blade of a skate, a pair of jaws located on said mounting plate on opposite sides of said slot and moveable relative to one another to engage opposite sides of said blades, and an operating mechanism connected to each of said jaws and operable to move said jaws conjointly from an open position to a closed position whereby said jaws remain equally spaced to opposite sides of a datum during such movement.  
         [0010]     Preferably the operating mechanism is supported on the plate and includes a flexible tensile member to transfer movement of one jaw to the other. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     These and other features of the preferred embodiments of the invention will become more apparent in the following detailed description in which reference is made to the appended drawings wherein:  
         [0012]      FIG. 1  is a perspective view of a skate sharpener and skate holder;  
         [0013]      FIG. 2  is a perspective view of the skate holder of  FIG. 1 .  
         [0014]      FIG. 3  is a front view of the skate holder shown in  FIG. 1 ;  
         [0015]      FIG. 4  is a rear view of the skate holder shown in  FIG. 1 ;  
         [0016]      FIG. 5  is an end view of the skate holder shown in  FIG. 1 ;  
         [0017]      FIG. 6  is a section on the line VI-VI of  FIG. 3 ;  
         [0018]      FIG. 7  is an exploded view of a portion of the holder of  FIG. 2 ;  
         [0019]      FIG. 8  is a partial view of the upper and lower clamping jaws moving between open end closed positions with a skate blade disposed between.  
         [0020]      FIG. 9  is a front view of a further embodiment of a component used in the skate holder of  FIG. 1 .  
         [0021]      FIG. 10  is a perspective view of an alternative embodiment of a skate holder.  
         [0022]      FIG. 11  is a view on the line XI-XI of  FIG. 10 .  
         [0023]      FIG. 12  is a perspective view of a further embodiment of a skate holder.  
         [0024]      FIG. 13  is a front elevation of the skate holder of  FIG. 12 .  
         [0025]      FIG. 14  is a view on the line XIV-XIV of  FIG. 13 .  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]     Referring therefore to  FIG. 1 , a skate sharpening apparatus  10  includes a skate holder  12  that supports a skate  14  having a skate blade  15 . The holder  12  is slideable on a work surface  18  so as to be manoeuvrable past a grinder  16  having a grinding wheel  20 . The grinding wheel  20  is positioned to rotate about a vertical axis in a horizontal plane and, upon engagement with the blade  15 , to grind the requisite profile.  
         [0027]     The details of the holder  15  can be seen in more detail in  FIGS. 2 through 7 . The holder  12  has a base  22 . A pair of handles  26  are provided on the base  22  to facilitate manipulation of the holder  12  on the worktop  18 . A mounting block  28  is secured to an upturned lip  24  of the base  22  by bolts  30 . The position of the mounting block  28  relative to the base is adjusted by means of set screws  32  which are threaded into the base  22  and bear against the underside of the mounting block  28 . The set screws  32  provide a nominal or coarse adjustment for the disposition of the mounting block  28  relative to the base  22  to ensure alignment between the holder  12  and the base  22 .  
         [0028]     The mounting block  28 , has an open ended slot  34  at each end in which a pair of cam members  42  are mounted. Each of the cam members  42  are mounted on threaded pivot bolts  44  secured to the lower edge of a mounting plate  40 . The cam members  42  provide an outer surface that is eccentric to the bolts  44  and have a radial handle  46 . The cam member  42  is dimension to be a close fit within the slot  34  such that rotation of the cam member  42  on the bolts  44  provides relative vertical adjustment between the plate  40  and the mounting block  28 . This arrangement provides a fine alignment of the plate  40  relative to the base  22  with the locking bolts  30  clamping plate  40  to the mounting block  28  after the required alignment has been achieved,  
         [0029]     The plate  40  has a planar central portion  50  and curved end portions  52 . An elongate slot  54  extends through the central portion  50  into each of the end portions  52  and is dimensioned to receive the blade  15  of a skate with adequate clearance to accommodate different sizes and thicknesses. A pair of jaws  56 ,  58  are slideably mounted on the central portion  50  and are moveable by an operating mechanism  60  between an open position in which the slot  54  is relatively unencumbered and a closed potion in which the jaws  56 ,  58  engage the skate blade  15 . Referring again to FIGS.  4  to  7 , the jaws  56 ,  58  each have a pair of slots  62  that receive a guide pin  64  secured to the mounting plate  40 . The guide pin  64  is a sliding fit within the slot  62  and therefore constrains the jaws  56 , 58  for movement in a direction perpendicular to the axis of the slot  54 .  
         [0030]     The upper jaw  56  has a follower recess  66  formed between the slots  62  to receive a cam  68 . The cam  68  is a close fit within the recess  66  and is secured by a retainer  70  to an actuator spindle  72  for rotation with the spindle  72 . The spindle  72  is rotatably mounted in the support plate  40  and is secured at its opposite end to a lever  74 .  
         [0031]     The lever  74 , which forms part of the operating mechanism  60 , has a cable  76  secured to it by a fastener  78  at a location spaced from the spindle  72 . The cable  76  is entrained within a recess  77  extending around the periphery of the plate  40  by a set of guide pulleys  80  each of which is rotatably secured to one of the end portions  52  adjacent to corners of the guide plate  40 . The cable  76  also runs through slides  82  positioned between the pulleys  80  and jaws  56 ,  58  to cause the cable  76  to conform generally to the curvature of the end portions  52 . The length of cable  76  may be adjusted by a threaded connector  79  so that the cable is taut around the pulleys  80 .  
         [0032]     The cable  76  is attached on its lower run to a pair of actuating arms  84 , each of which is secured to respective spindles  86 . The spindles  86  extend through the mounting plate  40  and are connected to respective ones of a pair of cams  88 . The cams  88  are located within respective follower recesses  90  in the lower jaw  58 , similar to the recess  66 , and the jaw  58  is retained by a retainer  92  secured to the spindle  86  to ensure the cams  88  rotate with the spindles  86 .  
         [0033]     In operation, the mounting plate  40  is adjusted relative to the base  22  using the mounting block  28  such that the longitudinal axis of the slot  54 , which acts as a datum, is aligned with the plane of the grinding wheel  20  and is positioned on the center line of the wheel  20 . The skate blade  15  is then inserted into the slot  54  and the handle  74  rotated to move the jaws  56 ,  58  into engagement with the blade  15 . As the handle  74  is rotated, the cam  66  is likewise rotated and causes the jaw  56  to move inwardly toward the blade  15 . The movement of the handle  74  is also transmitted through the cable  76  to each of the actuating arms  84 . The spindles  86  are thus rotated causing the cam  88  to cause a corresponding displacement of the jaw  58  toward the blade  15 . The jaws  56 ,  58  are thus brought into engagement with the blade  15  so that the blade  15  is held securely between the jaws and in alignment with the wheel  20 .  
         [0034]     It will be apparent that the attachment points of the cable  76  to the handle  74  and the actuating arms  84  are chosen such that an equal and opposite displacement of the jaws  56 ,  58  is obtained. This ensures that the blade  15  is maintained on the center line of the slot  54  in alignment with the wheel  20  as the jaws are moved into the clamping position. Accordingly, different thicknesses of blade can be accommodated without adjusting the disposition of the slot relative to the plane of the wheel  20 .  
         [0035]     With the blade  15  secured, the base  22  can be manipulated to bring the blade into engagement with the wheel  20  and grind the required profile onto the edge of the blade  15 . After the grinding is complete, the handle  74  is simply rotated in the opposite direction to release the jaws  56 ,  58  and permit removal of the blade. It will be noted that the operating system  60  is contained on the plate  40  and thus allows unencumbered access to the skate during sharpening.  
         [0036]     The eccentricity of the cams is selected such that, over the typical range of blade thicknesses, the engagement between the cams and the respective recesses is essentially self locking. Thus, after the handle  74  is moved to bring the jaws into the clamping position, the handle may be released and the jaws will remain engaged with the blade.  
         [0037]     It is found that the entrainment of the cable  76  over the pullies ensures a free movement of the cable to ensure that conjoint movement of the cam members is obtained. Whilst the routing of the wire within a sheath might also be used, it is believed that the entrainment around the pullies inhibits potential binding with the sheath.  
         [0038]     It will of course be appreciated that the handle  74  may be separated from the actuation of the cam so that the handle may be at either end of the support plate  40  and operate the cam through an arm similar to that used on the lower jaw  58 .  
         [0039]     In certain circumstances the forces applied to the jaws  56 ,  58  through the operating mechanism  60  may be sufficient to deflect the upper portion of the mounting plate  50  which in turn could result in the blade not being exactly centered. A further embodiment of mounting plate is shown in  FIG. 9  in which like components will be shown with like reference numerals with a suffix a added for clarity.  
         [0040]     Referring therefore to  FIG. 9 , a mounting plate  50   a  has a central slot  54   a  and a peripheral groove  77   a . It will be understood that the operating mechanism and jaw are mounted on the mounting plate  50   a  in a manner similar to that described above. Similarly, the plate  50   a  may be secured to a mounting block  28   a  by bolts  44   a  located on the lower edge of the plate  54   a.    
         [0041]     An elongate slit  100  is formed on the opposite side of the recess  77   a  to the slot  54   a . The slit  100  is placed above the block  28   a  and extends parallel to and over substantially the same length as the slot  54   a . The slit  100  is spaced from the lower edge of the slot  54   a  by a distance (indicated ‘x’) corresponding to the spacing of the upper edge of the slot  54   a  from the top edge of plate  54   a.    
         [0042]     The provision of the slit  100  and its placement relative to the lower edge of the slot  54   a  provides a pair of beams  102 ,  104  of substantially similar dimensions that support the operating mechanism  60 . The forces induced by the engagement of the jaws  56   a ,  58   a  with the blade are thus reacted by a similarly dimensioned support and the deflection of each of the supports is similar. Thus, the blade remains centered within the slot and variations in the load supplied through the cam mechanism to the jaws will cause equal and opposite displacement of the support portions of the plate  50   a  to maintain the required alignment.  
         [0043]     In the above embodiments shown in  FIGS. 1 through 9 , the skate holder  12  may accommodate blades of different configurations but may be either solid or with cut outs. However, a substantial number of blades intended for ice hockey use are provided with the central portion of the blade removed which provides the opportunity for a simpler clamping mechanism as shown in  FIGS. 10 and 11 . In the embodiment of  FIGS. 10 and 11 , like components will be identified with like reference numerals with a suffix b added for clarity.  
         [0044]     Referring therefore to  FIG. 10 , the skate holder  12   b  has a mounting block  28   b  on which is supported a mounting plate  50   b . The mounting plate  50   b  has an elongate slot  54   b  and a parallel spaced slit  100   b  as described above with respect to  FIG. 9 . Adjustment of the mounting plate  54   b  relative to the base  22   b  is accomplished as described above with respect to  FIGS. 1 through 8  so that the slot  54   b  is aligned with the datum as required.  
         [0045]     The jaws  56   b ,  58   b  are secured to the upper and lower beams  102   b ,  104   b  by set screws  106 . The jaws  56   b ,  58   b  are thus fixed to the beams for movement with them  
         [0046]     The operating mechanism  60   b  includes a yolk  106  secured to the upper beam  102   b . The yolk has a channel  108  with a cam  66   b  mounted within the channel  108  for rotation on the pivot  72   b . A handle  74   b  is secured to the pivot  72   b  to effect rotation of the cam within the channel  108  and the cam  66   b  is aligned with the beam  102   b.    
         [0047]     A follower  110  engages the surface of the cam  66   b  and is supported in a bar  112 . The bar  112  is slidably supported in the yolk  106  with the terminal portion extending across the channel  108 . The follower  110  is threaded into the terminal portion  114  so that it may be adjusted relative to the cam  66   b.    
         [0048]     The lower end  115  of the bar  112  is secured to a block  116  mounted on the beam  104   b . In operation, the blade is inserted between the jaws  56   b ,  58   b  with the bar  112  removed. The bar is then inserted into the blocks  116  and yolk  106  and secured to the block  116 . The follower  110  is then adjusted so as to be slightly clear of the cam  66   b  and the handle  74   b  used to rotate the cam  66   b  within the channel  108 . The eccentricity of the cam  66   b  causes the bar  112  to be displaced and apply a force between the beams  102   b ,  104   b . As the beams have substantially identical cross section, the deflection of each of the beams is the same and the jaws  56   b ,  58   b  move into engagement with the blade to maintain it on the datum. After sharpening of the blade, the cam  66   b  is released, the bar  112  removed and the skate removed from the slot  54   b.    
         [0049]     The arrangement shown in  FIGS. 10 and 11  maintains the jaws  56   b ,  58   b  equally spaced from a datum. The mechanism  60   b  is relatively robust and may readily be used where the configuration of the blade permits the passage of the bar  112 . It will also be appreciated that the mounting plates  50   b  can readily be removed and replaced with the alternative configuration of mounting plate such as that shown in  FIGS. 1 through 8  or  FIG. 9  to allow a full range of blades to be sharpened.  
         [0050]     A further embodiment of the skate holder is shown in FIGS.  12  to  14 . The skate holder is a modification of that shown in  FIGS. 10 and 11  and like reference numerals will be used to denote like components with a suffix ‘c’ added for clarity. Referring therefore to FIGS.  12  to  14 , the skate holder  12   c  has a mounting block  28   c  with a mounting plate SOc secured to it. Jaws  56   c ,  58   c  are secured to the beams  102   c ,  104   c  and an operating mechanism  60   c  similar to that shown in  FIGS. 10 and 11  operates on a bar  112   c  to close the jaws  56   c ,  58   c . The bar  112   c  has a terminal portion  114   c  with follower  110   c  engaging the cam  66   c.    
         [0051]     The lower end  115   c  of the bar  112   c  projects inwardly to be received beneath the beam  104   c . The loads applied by the operating mechanism are thus applied in the same plane as jaws  56   c ,  58   c  to inhibit twisting of the beams  102   c ,  104   c.    
         [0052]     It will also be noted from  FIG. 14  that the mounting plate  50   c  is relieved to provide an inclined notch  120  in the vicinity of the lower end  115   c . The notch  120  permits the bar  112   c  to pivot relative to the mounting plate  50   c , as shown in ghosted outline and in  FIG. 12  to facilitate placement and removal of the skate blade.  
         [0053]     With the bar  112   c  pivoted to the open position, the blade can be fed over the bar  112   c  and between the jaws  56   c ,  58   c . The bar  112   c  is then pivoted to the closed position and the follower  110   c  engaged with the cam  66   c . The cam  66   c  is rotated to draw the jaws  56   c ,  58   c  toward one another and clamp the blade at the required height. When sharpening is complete, the bar  112   c  is again released and the blade removed.