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This application claims priority from U.S. Provisional Application Ser. No. 61/490,262, filed May 26, 2011. 
    
    
     BACKGROUND 
     The present invention relates to a device and method for trimming off the high spots in the pebble of the ice in a curling rink. 
     Curling is a sport in which players slide stones across a sheet of ice towards a target area. The condition of the ice is very important. The surface of the ice is treated both to obtain a specified degree of flatness and to obtain a surface texture referred to as pebbling. 
     The ice flatness specification for curling ice is +/−0.001″/5 ft. When pebble is applied to the ice sheet, the water droplets (pebble) do not freeze to a uniform height. Due to the contact area of the stone, the pebble that is higher will get crushed or smashed by the stone passing over top, causing the stone to run slower on the ice sheet. Trimming off the high spots of the pebble results in a uniform pebble with a clean surface, causing the stone to run at a uniform and constant speed. Adjustment of the angle of the blade on the trimming device determines how much of the pebble is trimmed off. A typical specification requires that two ounces of ice be removed from the pebble in treating a ten-foot-wide swath along the 145 foot length of the curling rink. 
     SUMMARY 
     An embodiment of the present invention provides a device for trimming off the high points of the pebble of the ice using a single, long blade. A single blade facilitates the uniform adjustment of the angle of the blade compared to adjusting the three or four shorter blades present in prior art devices. However, the use of a single blade creates problems in maintaining the flatness of the blade over such a long length without requiring a much thicker and heavier blade, which has to be machined to very tight tolerances. 
     One embodiment of the present invention uses a plurality of paired sets of setscrews to adjust the flatness of the blade. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a device for trimming off the high spots of a curling rink; 
         FIG. 2  is a perspective view of the frame, mounting block, and blade of the device of  FIG. 1 , with the front and side covers of the frame removed for clarity; 
         FIG. 3  is a rear, perspective view of the mounting block and blade of  FIG. 2 , including the pivot blocks; 
         FIG. 4  is an enlarged, broken away, perspective view of the mounting block, blade, and pivot block of  FIG. 3 ; 
         FIG. 5  is an end view of the blade, with the mounting block shown in a section taken along the line  5 - 5  of  FIG. 4 ; 
         FIG. 6  is another end view of the blade, with the mounting block shown in section taken along line  6 - 6  of  FIG. 5 ; 
         FIG. 7  is an enlarged, broken away, perspective view of the mounting block and angle adjustment mechanism of  FIG. 3 ; 
         FIG. 8  is an enlarged, broken away perspective view of the angle adjustment mechanism of  FIG. 7 , but with the frame installed (essentially a rear view of  FIG. 2 ); and 
         FIG. 9  is a perspective view of the blade, mounting block, and pivot block of  FIG. 3 , but shown with the blade and mounting block pitched forward relative to the pivot block. 
     
    
    
     DESCRIPTION 
       FIGS. 1-9  show a device  10  for trimming the high spots off of a sheet of ice. The device  10  includes a substantially rectangular frame  12  which houses a blade  14 , a mounting block  16 , and pivot angle blocks  18  at the left and right ends of the mounting block  16 , as described in more detail later. The frame  12  includes a top cover  17 , a front cover  20 , a rear cover  21 , and left and right end covers  22 . A handle  19  is attached to the rear cover  21  of the frame  12  and extends rearwardly and upwardly from the frame  12 , for use by the operator to push the device  10  across the ice rink. 
       FIG. 2  shows the blade  14  and the mounting block  16  in their relative positions inside the frame  12 . The front cover  20  and the left and right side covers  22  of the frame, as well as the pivot angle blocks  18 , have been removed for clarity in this view. The front cover  20  typically is hinged to the top cover  17 , so it may be flipped upwardly and rearwardly to gain access to the blade area to inspect the condition of the blade and to enable the user to collect and weigh the shaved ice resting on the blade  28  to determine whether the blade angle needs to be adjusted. 
       FIG. 3  shows the floating blade assembly  24 , which includes the blade  14 , the mounting block  16 , the pivot angle blocks  18 , and the blade angle adjustment mechanism  26 , described in more detail later. The blade  14  is a substantially flat, rectangular cross-section member with flat, horizontal top and bottom surfaces and a beveled edge  28  for scraping the ice. As explained later, in this embodiment, the blade  14  is five feet long and is bolted onto the bottom of the mounting block  16  via half-inch diameter bolts  30  (See  FIGS. 4-6 ) spaced at approximately 6-inch intervals along the length of the blade  14 . 
     Referring to  FIGS. 4-6 , the mounting block  16  is a 2 inch×2 inch square cross-section metal block, approximately five feet long, which supports the blade  14 . The mounting block  16  has flat, horizontal top and bottom surfaces and defines a plurality of vertically-oriented, half-inch diameter through bolt holes  32  (See  FIG. 6 ) for securing the blade  14  to the bottom of the mounting block  16  via bolts  30  and corresponding threaded openings  31  in the blade  14 . The bolt holes  32  are aligned substantially along the longitudinal centerline  34  of the mounting block  16 . As explained later with respect to the flatness adjustment of the blade  14 , this centerline  34  (when projected along the plane where the mounting block  16  meets the blade  14 ) acts as a pivot axis for the blade  14  relative to the mounting block  16 . 
     Referring to  FIG. 5 , the mounting block  16  defines a plurality of ¼ inch diameter, vertically-oriented, internally threaded set-screw holes  40 . Each set-screw hole  40  receives an externally threaded set screw  42 . Note that there are no corresponding openings in the blade  14  to match up with the set-screw holes  40  in the mounting block  16 . Therefore, the set screws  42  impinge directly upon the top surface  44  of the blade  14  when they are threaded beyond the bottom surface of the mounting block  16 . 
     The set-screw holes  40  (and thus also the set screws  42 ) are substantially paired up opposite each other, with the forward set screw of each pair centered on a forward set screw centerline  36  (See  FIG. 5 ) and the rear set screw of each pair centered on a rear set screw centerline  38 . The vertical axes of the forward set screws lie along a forward vertical plane which is perpendicular to the centerline  36 , and the vertical axes of the rear set screws lie along a rear vertical plane which is perpendicular to the centerline  38 . The centerlines  34 ,  36 ,  38  are parallel to each other, and the first set screw centerline  36  is the same distance forward of the bolt hole centerline  34  (toward the beveled edge  28  of the blade  14 ) as the second set screw centerline  38  is rearward of the bolt hole centerline  34 . The vertical axes of each pair of forward and rear set screw holes  40  preferably lie on a vertical plane that is perpendicular to the forward and rear vertical planes. 
     In this embodiment, the set screws  42  are located at approximately one inch intervals along their respective centerlines  36 ,  38 . It should be noted that, while the arrangement shown in this embodiment is preferred, the set screws  42  could be arranged differently, such as diagonally across from each other in a triangular pitch arrangement, for instance. 
     To adjust the blade  14  for flatness, the blade  14  is first mounted to the mounting block  16  via the ½ inch bolts  30 , with the flat top surface  44  of the blade  14  abutting the flat bottom surface of the mounting block  16 . The set screws  42  are then threaded into the set-screw holes  40  until they just bottom out on the top surface  44  of the blade  14 . The blade and mounting block assembly is then placed atop a master straight-edge, which is a block having a very flat top surface, and a light is placed behind the back of the assembly directing its light toward the front. A person standing in front of the blade  14  then can look for light shining through between the front of the blade  14  and the master straight edge to detect any gaps between the blade  14  and the master straight-edge, indicating that the blade  14  is not flat. To close a gap between the blade  14  and the master straight-edge (which brings the blade into flat condition), the front set screw  42  lying closest to the location where the gap is found is threaded against the top surface  44  of the blade  14 , pushing downwardly against the top surface  44  of the blade  14  forward of the bolt centerline  34  and causing that portion of the blade  14  to pivot downwardly about the bolt centerline  34  relative to the mounting block  16 . Since there is approximately a four (4) inch distance between the beveled edge  28  and the bolt centerline  34 , a very small downward movement of the top surface  44  of the blade  14  caused by the forward set screw  42  results in a significant downward movement of the beveled edge  28  to close the gap and bring the blade  14  to a flat condition at the longitudinal position corresponding to that particular set screw  42 . 
     If, during the flatness adjustment, the blade  14  is actually pushed too far down, then the person making the adjustment backs off the front set screw  42  at the longitudinal position corresponding to the location where the blade  14  is too far down. The opposing rear set screw  42  lying along the rear centerline  38  then may be threaded further down to push downwardly on the blade  14  rearward of the bolt centerline  34  in order to correct the problem and bring the blade  14  back to the desired flatness. 
     Essentially, the blade  14  is pivoted very slightly about the bolt centerline  34  by threading in one or more set screws  42  along the front set-screw centerline  36  (and backing off the corresponding set screws  42  along the rear set-screw centerline  38 ) to lower the beveled edge  28  of the blade  14  to bring the blade  14  into the desired degree of flatness. If the blade  14  is already too low (or if the above adjustment over-corrected the problem), the procedure is reversed; that is, the blade  14  is pivoted very slightly about the bolt centerline  34  by threading in one or more set screws  42  along the rear set-screw centerline  38  (and backing off the corresponding set screws  42  along the front set-screw centerline  36 ) to raise the beveled edge  28  of the blade  14 . 
     This flatness adjustment is intended to move the beveled edge  28  of the blade  14  just a few thousandths of an inch and to do so at very localized points along the length of the blade  14  to bring the blade  14  to the desired degree of flatness. A different adjustment for setting the angle of blade  14  will be described later. 
     Referring now to  FIGS. 3 and 4 , the floating blade assembly  24  includes pivot angle blocks  18  at each end of the mounting block  16 . These pivot angle blocks  18  are mounted to the mounting block  16  by means of circular cross-section pins  47 , which permit pivotal rotation of the mounting block  16  relative to the pivot angle blocks  18  about an axis of rotation  46 , as best shown in  FIG. 9 . The pivot angle blocks  18  are mounted to the frame  12  via bolts  48  (See  FIG. 1 ) which are threaded into bolt holes  50  in the pivot angle blocks  18 , so the pivot angle blocks  18  are stationary relative to the frame  12 . 
     The frame  12  rests on top of the ice, and the pivot angle blocks  18  are securely attached to the frame  12 , so they are not allowed to move relative to the frame  12 . However, the floating blade assembly  24  is pivotably mounted to the pivot angle blocks  18  such that the blade  14  may be moved from a first position in which its bottom surface is substantially coplanar with the surface of the ice  52  (See  FIG. 3 ), to a second position (See  FIG. 9 ) wherein the bottom surface of the blade  14  is at an angle α relative to the surface of the ice  52 . This angle α is shown exaggerated in  FIG. 9 . In the usual practice, the angle α would likely be adjusted to a maximum angle on the order of two to four degrees. The blade angle adjustment mechanism  26  is used to obtain and retain this relatively small angle α, as described below. 
     Referring to  FIGS. 7 and 8 , the blade angle adjustment mechanism  26  includes two spaced-apart brackets  54  which are secured to the rear face  56  of the mounting block  16 . In this embodiment, the brackets  54  are welded to the mounting block  16 , but other known mounting means, such as bolting, could be used. A piece of bar stock  58  is pivotably mounted between the ends of these two brackets  54  by means of pins  61 , such that the bar stock  58  may pivot about the pivot axis  63  as shown by the arrow  60 . The bar stock  58  is releasably secured to the brackets  54  so that the frame  12  may be mounted over the floating blade assembly  24 , with the brackets  54  projecting through slots  62  in the rear cover  21  of the frame  12 , as best shown in  FIG. 8 , prior to full assembly of the blade angle adjustment mechanism  26 . 
     The bar stock  58  defines a threaded vertical opening  64  which receives the threaded shaft  66  of the hand crank  68 . The threads in the threaded opening  64  and in the matching shaft  66  of the hand crank  68  are fine threads such that one complete turn of the hand crank  68  results in a very small amount of thread advance. This allows very fine adjustment of the angle of the blade  14  as explained below. 
     Referring to  FIGS. 1 and 8 , a bracket  70  is secured to the frame  12 . In this embodiment, the bracket  70  is welded to the top cover  17  of the frame  12 . This bracket  70  defines a top opening  72  adapted to receive and rotationally support the hand crank  68 . The threaded shaft  66  of the hand crank  68  passes through the top opening  72 , but the head  74  of the hand crank  68  is too large to go through the top opening  72 . The weight of the bar stock  60  causes the head  74  of the hand crank to rest on the top surface of the bracket  70 , so that the hand crank  68  and the threaded shaft  66  are fixed-height supported on the frame  12  by the bracket  70 . Therefore, as the hand crank  68  is rotated by the operator, the threaded shaft  66  also rotates and threads into the threaded opening  64  of the bar stock  58 , pulling the bar stock  58  upwardly toward the bracket  70 . The bar stock  58  pivots slightly in the direction of the arrow  60  as it is drawn up towards the bracket  70  in order to keep the shaft  66  aligned with the threaded opening in the bar stock  58  to prevent it from locking up as the blade angle is being adjusted. 
     Since the lower brackets  54  are secured to the rear surface  56  of the mounting block  16 , as the bar stock  58  and the lower brackets  54  are drawn up toward the upper bracket  70 , the floating blade assembly  24  is tipped forward, pivoting on the pivot angle blocks  18 , as shown in  FIG. 9 . System friction prevents the hand crank  68  from moving and holds the blade  14  at the desired angle α once the operator has set the angle. 
     To adjust the angle α, the operator turns the hand crank  68  to a first setting. He then pushes the device  10  along the full 145 foot length of the curling ice rink. In this embodiment, the blade  14  is approximately 5 feet long, so a 5 foot swath of ice is trimmed by the device  10  in a single pass. The operator then takes a second pass along the length of the ice rink to make a total swath width of 10 feet. He then opens up the front cover  20  of the frame  12  and collects any ice which has accumulated on the blade  14 . 
     The operator weighs the amount of ice collected and compares this weight to the desired weight of two ounces. If more than two ounces were collected, he turns the hand crank  68  in a counter-clockwise direction to reduce the angle α of the blade  14 . If less than two ounces were collected, he turns the hand crank  68  in a clockwise direction to increase the angle α of the blade  14 . This process is repeated until the amount of ice collected is within the desired tolerance of the two ounce goal. The ice rink may then be re-pebbled and the entire ice surface trimmed to the specification. 
     It will be obvious to those skilled in the art that modifications may be made to the embodiment described above without departing from the scope of the present invention.

Summary:
A device for trimming the high points off of the ice of a curling rink includes an elongated blade mounted to an elongated mounting block, and a plurality of setscrews threaded into threaded openings in the mounting block for adjusting the flatness of the blade, enabling a long blade to be used that is both accurate and relatively inexpensive.