Patent Publication Number: US-11638975-B2

Title: Mower reel grinding system with rotating rear brackets

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a non-provisional of U.S. Application Ser. No. 62/627,002 filed Feb. 6, 2018, which is incorporated herein by reference. 
     BACKGROUND 
     Commercial mowers, such as those often used for maintaining golf courses, for example, typically use reel-type mowing units which employ cylindrical cutting reels having a number of helical blades disposed about a central shaft. To maintain optimal cutting performance, the helical blades of the cutting reels must be regularly sharpened. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain principles of embodiments. Other embodiments and many of the intended advantages of embodiments will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts. 
         FIG.  1 A  is a perspective view of an example of a reel-type mower unit. 
         FIG.  1 B  is a schematic diagram generally illustrating a cross-sectional view of an example of a reel-type mower unit. 
         FIG.  2 A  is a schematic diagram generally illustrating a cross-sectional view of an example of a flat-ground helical blade. 
         FIG.  2 B  is a schematic diagram generally illustrating a cross-sectional view of an example of a helical blade having a relief or chamfer. 
         FIG.  3    is a perspective view of an example of a grinding system according to the present disclosure. 
         FIGS.  4 A- 4 D  illustrate examples of a traverse base assembly including spin-grinding and relief grinding assemblies according to one example 
         FIGS.  5 - 7    are perspective views of a grinding system according to examples of the present disclosure. 
         FIGS.  8 - 11    are block and schematic diagrams generally illustrating a grinding system and process according to examples of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following Detailed Description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. 
     It is to be understood that the features of the various exemplary embodiments described herein may be combined with each other, unless specifically noted otherwise. 
     Commercial mowers, such as those often used for maintaining golf courses, for example, typically use reel-type mowing units which employ cylindrical cutting reels having a number of helical blades disposed about a central shaft. To maintain optimal cutting performance, the helical blades of the cutting reels must be regularly sharpened, preferably as close as possible to OEM (original equipment manufacturer) specifications. In view of the above, grinding systems have been developed to sharpen helical cutting blades of such mowing units. 
       FIG.  1 A  is a bottom perspective view generally illustrating an example of a reel-type mower unit  10  for sharpening by a grinding system in accordance with the present disclosure. Reel-type mowing units, such as mower unit  10  typically include a frame structure  12  to which a rear roller  14 , a front roller  16 , a bedknife  18 , and a cylindrical cutting reel  20  are mounted, wherein cutting reel  20  includes a number of helical blades  22  disposed about a shaft  24 . 
       FIG.  1 B  is a simplified schematic diagram illustrating a cross-sectional view showing portions of a typical mower unit, such as mower unit  10 . For ease of illustration, frame  12  is not shown in  FIG.  1 B . As reel  20  rotates, as indicated by rotational arrow  26 , a perimeter surface  21  of reel  20  is defined by helical blades  22 . It is noted that the so-called perimeter surface  21  is not a continuous surface, but is defined by the outer edges of surfaces of helical blades  22 . While mowing, grass is cut at a sheer point  28  formed between the helical blades  22  and a leading edge of bedknife  18 . A height of cut, cic, of the mower unit is typically adjusted by adjusting the vertical height (z-axis) of front roller  16  relative to central shaft  24  of cutting reel  20 . A horizontal distance (y-axis) between a centerline of rear roller  14  and a centerline (i.e. axis of rotation) of cutting reel  20  is indicated as d R , and a horizontal distance between a centerline of front roller  16  and the centerline of cutting reel  20  is indicated at d F . 
     Because of the helical design of blades  22 , while mowing, grass clippings are pushed toward one end of the cylindrical cutting reel such that blade wear is uneven, with the wear increasing from one end the other such that, over time, the perimeter surface  21  of cutting reel  20  may assume a conical shape rather than a cylindrical shape. 
     One type of grinding process is referred to as a “touch-off” grinding process. Typically, during “touch-off” grinding, a shaft of a grinding wheel used to sharpen cutting reel  20  is adjusted to be parallel with perimeter surface  21  of cutting reel  20 . According to such process, the grinding wheel is first positioned at a first end of cutting reel  21 , and grinding wheel shaft is adjusted until the grinding wheel touches the perimeter surface  21  of cutting reel  21 . The grinding wheel is then positioned at a second end of cutting reel  20 , opposite the first end, and adjusted until the grinding wheel touches perimeter surface  21 . The grinding wheel is then moved back and forth in a reciprocating fashion along perimeter surface  21  of cutting reel  21  in the direction of shaft  24  of cutting reel  20 , while cutting reel  20  is being about spun about shaft  24  counter to the direction of spin of the grinding wheel in order to grind or “square off” the edges of the helical blades  22 . 
     While “touch off” grinding squares the edges of each helical blade  22 , because the shaft of the grinding wheel is paralleled with perimeter surface  21  of the cutting reel  20 , a “touch off” process does not “square” or “true” the overall shape of cutting reel  20  (i.e., it does not remove the conical shape). Since the grinding wheel is parallel to perimeter surface  21  of cutting reel  20 , if the perimeter surface  21  of cutting reel  21  had a conical shape before touch-off grinding, the perimeter surface  21  of cutting reel  20  will maintain the conical shape after completion of the touch-off grinding process. If the conical shape of the cutting real is severe enough, performance of the cutting reel can be adversely affected. Also, if the grinding wheel shaft does not align closely enough with the direction of the rotational shaft  24  of cutting reel  20 , the entirety of the edges of each of the helical blade  22   s  may not be sharpened. Users sometimes carry out the “touch off” grinding or sharpening process in order to save time (due to simplicity of the process) and/or when wear on a cutting reel is minimal. 
     Another type of grinding process, sometimes referred to herein as a “squaring process” or “trueing process” is carried out to return the perimeter surface  21  of cutting reel  20  to a true cylindrical shape. According to such a process, rather than paralleling the shaft grinding wheel to perimeter surface  21  of cutting reel  20 , the grinding wheel shaft is paralleled with the rotational shaft  24  of cutting reel  20  in both a vertical direction (x-z plane) and a horizontal direction (x-y plane). The grinding wheel is then moved back and forth in a reciprocating fashion in the direction of shaft  24  of cutting reel  20  as cutting reel  20  is spun counter to the grinding wheel to thereby square-off each helical blade and, thereby square or true to cutting reel to a true cylindrical shape (i.e., removes the coning). 
     A third type of grinding process, sometimes referred to as a “relief grinding process”, or simply “relief grinding” involves grinding a relief chamfer onto a back of each helical blade. According to one example, such process comprises a two-part process. In a first part, a “trueing” or “squaring” grinding process is carried out to ensure that the cutting reel has a true cylindrical shape. In a second part, a grinding wheel is successively guided along a back edge of each individual helical blade to create a relief or chamfer on the back edge which thereby forms a finer and more efficient cutting edge on each helical blade. 
       FIG.  2 A  is a schematic diagram generally illustrating portions of a blade  22  after a spin grinding process, which includes positioning a grinding wheel of the grinding system and the cutting reel relative to one another so that the ends of all blades  22  of reel  20  are ground as cutting reel  20  is spun to “true” cutting reel  20  to a cylindrical shape.  FIG.  2 B  is a schematic diagram generally illustrating blade  22  after a relief grinding process, where a grinding wheel is positioned to grind a relief bevel  25  having a relief angle θ onto a backside (or trailing edge) of blade  22  to form a cutting edge  27  that interacts with bedknife  18  to form sheer point  28 . 
     In order to ensure that the grinding process returns reel  20  and blades  22  to OEM specifications, reel  20 , and thus, helical blades  22 , must be properly positioned and aligned relative to the grinding wheel(s) used during the grinding process. Some grinding systems secure to the front roller of the mower unit, such as front roller  16  of mower unit  10  illustrated above by  FIGS.  1 A and  2 A , with some type of clamping/support structure. The support structure and grinding wheel are then adjusted relative to one another to achieve proper positioning of reel  20  relative to the grinding wheel. Such an adjustment process may be difficult, as the distance d F  between the centerline of front roller  16  and the centerline of shaft  24  of cutting reel  20  is often different between mower units  10  from different manufactures, and is often different between models of mower units  10  from the same manufacturer. Furthermore, the front roller  16  can be positioned at different horizontal locations relative to shaft  24  for various purposes (e.g. for the installation of accessories such as groomers and brushes) so that distance dF can be different even between the same models of cutting units from the same manufacturer. As such, it is often necessary to adjust the positioning of the grinding system to achieve proper alignment each time a different mower unit  10  is to be sharpened, even when mowers units of the same model from the same manufacturer are being consecutively sharpened. Such alignments are time consuming and can result in inconsistent and undesirable grinding results. 
     In contrast to the distance d F  between the centerlines of the front roller  16  and reel  20 , while the vertical position of rear roller  14  may vary, the horizontal distance d R  between the centerlines of the rear roller  14  and shaft  24  of cutting reel  20  of a given model of mowing unit is typically at a constant distance, or at least within a tight range of distances. Additionally, attachments and accessories, such as brushes, groomer, and thatchers, for example, are not typically mounted on the rear of the mowing units. 
       FIG.  3    is a perspective view illustrating portions of a grinding system  50 , according to the present disclosure, which enables each of the above described grinding processes (“touch-off”, “squaring/trueing” and “relief” grinding) to be quickly and accurately performed. As will be described in greater detail below, to provide quicker, more accurate, and consistent horizontal positioning (in an x-y plane) of cutting reel  20  relative to a shaft of a grinding reel, and thereby provide accurate and consistent “squaring/trueing” and relief grinding processes, grinding system  50  includes moveable mounting brackets that releasably secure to the rear roller  14  of mower unit  10  (or to another predefined point on mower unit  10  that is at a known, fixed distance from shaft  24  of cutting reel  20 ). The mounting brackets are moveable linearly in the horizontal plane (x-y plane) to one of a number of predetermined positions along a positioning axis based on characteristics of the mower reel unit  10  (where such characteristics include the manufacturer of mower unit  10  and the size of cutting reel  20 , for example) so as to place the cutting reel  20  at a desired horizontal position relative to the shaft/axis of the grinding wheel, which is at fixed horizontal position (i.e., in the x-y plane). 
     As described below, the rear mounting brackets are linearly moveable in the horizontal plane (x-y plane) to preselected positions corresponding to different types of mower units (e.g., different models and manufacturers), and are rotatable together as a unit about a pivot axis so as to provide quick and accurate horizontal alignment of reel  20  (i.e., in a horizontal x-y plane) relative to a grinding wheel axis that is at a fixed horizontal position to thereby enable accurate and reproducible spin grinding and relief grinding processes. Additionally, each end of the grinding axis of the grinding wheel is independently adjustable in the vertical direction (i.e., in the x-z plane) to enable touch-off grinding of reel  20 . In other examples, grinding system  50  further includes a controller that provides automated paralleling of rotational axis  24  of reel  20  with the grinding wheel axis in at least the vertical plane based on inputs from one or more alignment gauges. As such, according to examples which will be described in greater detail herein, grinding system  50  enables accurate spin and relief grinding processes while also enabling touch-off grinding. 
     With reference to  FIG.  3   , in one example, grinding system  50  includes a mounting platform  60  including a plurality of sets of predetermined positions (e.g., holes)  62  at which mounting brackets  64  can be positioned, where each set of predetermined positions corresponds to at least one type of mower unit, such as a particular model from a particular manufacturer (including different reel diameters and widths, for example. For example, see U.S. Pat. No. 9,776,297, which is incorporated herein by reference. In one example, mounting platform  60  and, thus, mounting brackets  64 , is rotatable in the horizontal plane (x-y plane) about a pivot point/axis  66 , as indicated by rotational arrow  68 , via a horizontal adjustment mechanism  65  (such as wheel  65 ). Locking mechanisms  69  are operable to secure mounting platform (and mounting brackets  64 ), at a desired position in the horizontal plane (such as parallel to a grinding wheel axis, for example), after mounting platform  60  has been rotated about pivot axis  66  to a desired position via operation of hand-wheel  65 . 
     A clamping assembly  70  includes a flange  72  to secure a rear roller  14  to mounting brackets  64  (v-brackets) via a locking mechanism  74  (e.g., a cam mechanism). 
     A front mounting assembly  80  includes a vertically adjustable support pedestal  82  and a clamping mechanism  84  to secure to a front roller  16  of a mower unit  10 . 
     A spin drive motor  90  is employed to couple to shaft  24  and to drive/spin a reel  20  of a mower unit  10  mounted to grinding system  50 . In one example, spin drive motor  90  is mounted to an articulating arm system  92 . 
     A traverse base assembly  100  includes end plates  102   a  and  102   b  between which a guide system  104 , such as guide rods  104   a  and  104   b , and a grinding shaft  106  (having a grinding axis  108 ) extend. In one example, grinding shaft  106  is driven by a grinder drive motor  107  via a belt  109  (see  FIG.  4 C ). 
     In one example, a spin-grinding assembly  120 , including a spin-grinding carriage  122  and a spin-grinding wheel  124 , is mounted to traverse base assembly  100 , with carriage  122  slideably coupled to guide rods  104   a / 104   b , and spin-grinding wheel  124  coupled to grinding shaft  106 . In one example, spin-grinding assembly  120  is driven back and forth along guide rods  104   a / 104   b  and grinding shaft  106  by drive motor  130  via drive belt  132 . 
     With reference to  FIGS.  4 A- 4 D , which respectively illustrate perspective, top, front, and side views of traverse base assembly  100 , according to one example, a relief-grinding assembly  140  is also mounted to traverse base assembly  100 . In one example, a relief-grinding assembly  140  includes a relief-grinding carriage  142 , a relief-grinding wheel  144 , and a relief grinding index/guide assembly  146  (see U.S. Pat. Nos. 6,290,581 and 9,776,297, each of which are incorporated herein by reference), with relief-grinding carriage  142  slideably coupled to guide rods  104   a / 104   b , and relief-grinding wheel  144  coupled to grinding shaft  106 . In one example, relief-grinding assembly  140  is driven back and forth along guide rods  104   a / 104   b  and grinding shaft  106  by a drive motor  130  via a drive belt  132 . 
     In one example, spin-grinding assembly  120  and relief-grinding assembly  140  are separately coupled to guide system  104  via engagement mechanisms  128  and  148 . 
     In one example, traverse base assembly  100 , including guide system  104 , grinding shaft  106 , spin-grinding system  120 , relief-grinding system  140 , and drive motors  107  and  130 , is vertically adjustable at each end (such as right end  101   a  and left end  101   b ) via respective vertical adjustment systems  150  and  160 . In one example, vertical adjustment systems  150  and  160  each include respective hand wheels  152  and  162  for vertically adjusting (i.e., in the z-direction) the right and left ends  101   a  and  101   b  of traverse base assembly  100  (see arrows  103   a / 103   b  in  FIG.  4 C ). In one example, adjustment systems  150  and  160  each include and adjustment motor  154  and  164  for vertically adjusting the right and left ends  101   a  and  101   b  of traverse base assembly  100 , based on inputs from one or more measurement gauges (which will be described in greater detail below). In one example, adjustment system  150  includes both wheel  152  and motor  154 , and adjustment system  160  includes both wheel  162  and motor  164 . 
       FIG.  5    is another perspective view of grinding system  50 , and illustrates a controller  170 . 
       FIGS.  6  and  7    are perspective views of grinding system  50  with a mower unit  10  having a rear roller  14  mounted to rear brackets  64  and a front roller  16  secured to support pedestal  82  of front mounting assembly  80  via clamp  84 . 
       FIGS.  8 - 11    generally illustrate a system and method of carrying out a trueing/squaring grinding process, according to one example. In one example, to begin the grinding process, a user sets the left end  101   b  of traverse assembly  100  to a zero position so that grinding shaft  106  is at a known vertical position at left end  101   b . In one example, a user sets the left end  101   b  to the zero position via wheel  162 . In one example, a user sets the left end  101   b  to the zero position by initiating a spin-grinding process via controller  170 , whereby controller  170  sets left end  101   b  to the zero position by controlling drive motor  164  via a control line  171 . 
     In one example, after the left end  101   b  is set to the zero position, spin-grinding carriage  122  is moved to location D 2  (which is at a known distance D 2  from left end  101   b  of traverse base assembly  100 ). With reference to  FIG.  10   , after spin-grinding carriage  122  has been moved to location D 2 , an electronic linear distance gauge  180  is mounted on a first mounting element  172  so as to be positioned vertically with the rotational shaft  24  of reel  20  and provides, via an extendable shaft  182  (e.g., spring loaded shaft), a measurement of the distance to the perimeter of reel  20  (i.e., an edge of a helical blade at its lowest point) to controller  170 . In one example, a user then adjusts the height of support pedestal  82  until controller  170  indicates that the lowest perimeter edge of reel  20  is at a desired height d BR  from spin-grinding carriage  122 . 
     After the desired height d BR  has been achieved, as illustrated by  FIG.  10   , while still mounted on first mounting element  172  and at the first location D 2 , reel  20  is rotated until electronic liner distance gauge  180  provides a measurement of the distance d V2  to rotational shaft  24  of reel  20  to controller  170 . 
     Spin grinding carriage  122  is then moved to location D 1  (which is at a known distance D 2  from left end  101   b  of traverse base assembly  100 ). When at position D 1 , similar to that illustrated by  FIG.  10   , electronic liner distance gauge  180  provides a measurement of the distance d V1  to rotational shaft  24  of reel  20  to controller  170 . 
     Based on the known distances D 2  and D 1  from the left end  101   b  of traverse base assembly  100  at which vertical distance measurements d V2  and d V1  were taken, controller  170  determines a distance d ADJ  by which to adjust right end  101   a  of traverse base assembly  100  so that grinding shaft  106  is vertically paralleled with rotational axis  24  of cutting reel  20 . In one example, controller  170  adjusts the height of right end  101   a  of traverse assembly  100  by the distance d ADJ  by operating drive motor  154  via control line  173 . In one example, a user may adjust the height of right end  101   a  by the distance d ADJ  via wheel  152  (with controller  170  providing indication of proper adjustment via a set of indicating lights, e.g., raise, lower, stop lights). 
     In one example, after vertical alignment has been achieved between grinding shaft  106  and rotational shaft  24 , horizontal alignment is made between grinding shaft  106  and rotational shaft  24  of reel  20 . Similar to that described above with regard to vertical alignment, during horizontal alignment, measurements d H2  and d H1  of the distance to the rotational shaft  24  of reel  20  are again taken at locations D 2  and D 1 , except with the electronic linear distance gauge  180  mounted on pin  174  in instead of on pin  172  (see  FIG.  11   ). In a similar fashion to that described above with respect to the vertical adjustment, controller  170 , based on measurements d H2  and d H1 , determines a rotational adjustment, R ADJ , which is required to be made to mounting platform  60  about pivot  66  so that grinding shaft  106  is horizontally paralleled with rotational shaft  24  of reel  20 . In one example, the adjustment can be made by a user via wheel  65  with indication provided controller  170  via a set of indicating lights, or made automatically via a motor (not shown) controlled by controller  170 . In one example, is noted that when at the second mounting position  172 , measuring gauge  180  must be at an angle of 20 degrees or greater from vertical, as measured from a vertical line extending through rotational shaft  24 . 
       FIG.  9    is a block and schematic illustrating a simplified top view of a mower unit  14  mounted on brackets  64  of rotating mounting plate  60  via rear roller  14 , where the dashed lines indicate and initial position of mounting plate  60 , and the solid lines indicate a position of mounting plate  60  about pivot axis  66  by the amount R ADJ  so that axis  24  of cutting reel  20  is paralleled with grinding axis  106  in the x-y plane. It is noted that grinding axis  106  is fixed in the x-y plane, while mounting plate  60  is fixed in the x-z plane. 
     After grinding shaft  106  has been both vertically and horizontally aligned with rotational shaft  24  of reel  20 , a trueing/squaring grinding process is carried out to square or true reel  20  to a cylinder. In one example a relief grinding process may carried out thereafter using relief grinding assembly  140 . It is noted that spin grinding assembly  120  and relief grinding assembly  140  are separately and independently coupled to grinding shaft  106  and guide assembly  104  during the spin and relief grinding processes. 
     Although illustrated as a mechanical gauge, any suitable type of measuring gauge may be employed for gauge  180 , such as a laser gauge, for example. In one example, two laser gauges may be mounted to carriage  122 , one at each location  172  and  174 . 
     In another mode, grinding system  50  enables touch-off grinding via manual vertical adjustment of grinding shaft  106  via wheels  152  and  154 , wherein such touch-off grinding is improved based on use of rear brackets  64  being moveable to horizontal positions corresponding to the type of mower unit being sharpened and to grinding shaft  106  being fixed in the horizontal plane. Such touch-off grinding is performed by independently moving the opposing ends  101   a  and  101   b  in the z-direction to parallel grinding shaft  106  with the perimeter surface  21  of cutting reel  20 . 
     In a trueing/squaring grinding process, grinding system  50  provides accurate trueing or squaring of cutting reels to cylinder shapes based on the use of rear mounting brackets  64  and the paralleling of grinding shaft  106  with rotational shaft  24  of reel  20  via the gauging and alignment system described herein. In another mode, grinding system  50 , in addition to providing spin-grinding for trueing the reels to their desired cylindrical shape, further provides relief grinding via relief grinding assembly  140 . 
     Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.