Abstract:
A reel mower assembly including at least one magnetized backing plate mounted to a frame of a greensmower, a bedknife retainer magnetically retained in proximity to the backing in an operating position, and a bedknife interposed between the backing and the bedknife retainer such that the bedknife is oriented in cutting relationship with the reel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/568,124, filed on May 4, 2004. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to a reel mower, and more particularly, to a disposable magnetic bedknife for a reel mower.  
       BACKGROUND OF THE INVENTION  
       [0003]     Reel mowers use a scissoring action, rather than a tearing action, to shear grass and like foliage. Such reel mowers typically provide a high quality cut, but require more maintenance than rotary mowers. Golf course superintendents prefer such mowers where appearance and healthy grass are important, such as on golf greens.  
         [0004]     In a typical reel mower assembly, an attachment member, commonly called a bed bar or backer, attaches to the apparatus in rigid relationship to the reel, and a replaceable bedknife attaches to the bed bar. The bedknife is maintained parallel to the reel axis and in close proximity to the reel knives so that the reel and the bedknives achieve a quality sheering action. Typically, an adjustment mechanism allows movement of the bed bar relative to the reel so that the bedknife can be moved into proper relationship with the rotating reel.  
         [0005]     Conventionally, the bedknife attaches to the bed bar with a plurality of screws placed through holes in the bedknife, and by further engaging threaded holes in the bed bar. Such conventional arrangements typically use ten or more screws to attach the bedknife to the bed bar. Thus, replacing the bedknife requires removing the screws, changing the bedknife, and screwing the new bedknife to the bed bar. Typically, the bedknife attaches to the underside of the bed bar so that the mower must be sufficiently raised or partially disassembled to access the underside of the reel mower assembly to remove the screws and the bedknife. A reel mower unit used in a typical golf course application may use multiple reel mower assemblies. Changing bedknives on a reel mower, especially a mower with multiple reels, requires significant manual labor time and corresponding downtime.  
         [0006]     When the bedknife is screwed to the bed bar, stones or similar debris entering the mower can jam between the fixed bedknife and the reel, damaging one or more portions of the reel mower assembly. Bedknives may also sustain damage when contacting a substantially buried obstruction. Damage to the bedknife can be quite costly and problematic, given the close tolerances required for proper operation. Furthermore, a bedknife tends to dull the more often it is used. Grinding a new cutting edge onto a bedknife also requires time and expertise, thereby increasing maintenance costs.  
       SUMMARY OF THE INVENTION  
       [0007]     This application relates to a reel mower assembly comprising a reel mower rotatably mounted to a frame, a drive operative to rotate the reel about a reel axis, at least one magnetized backing mounted to the frame, a bedknife retainer magnetically retained in proximity to the backing in an operating position, and a bedknife interposed between the backing and the bedknife retainer such that he bedknife is oriented in cutting relationship with the reel. Alternatively, this application also relates to a bedknife retainer magnetically retained in proximity to the backing in an operating position, and the bedknife retainer carrying at least one bedknife. The reel mower assembly further includes an engagement device operative to prevent sliding movement of the bedknife with respect to the backing while allowing the retainer to move away from the backing when a separating force is exerted on the retainer in a direction away from the backing that is greater than an attractive force exerted on the retainer by the backing when the retainer is in the operating position.  
         [0008]     This application also relates to a reel mower assembly comprising a frame, a primary mover attached to the frame for displacing the mower, a power source supported by the frame for operating the primary mover, a reel mower rotatably mounted to the frame, a drive operative to rotate the reel about a reel axis, and at least one magnetized backing mounted to the frame. The reel mower assembly further includes a bedknife retainer magnetically retained in proximity to the backing in an operating position, and a bedknife interposed between the backing and the bedknife retainer such that the bedknife is oriented in cutting relationship with the reel. Alternatively, the reel mower assembly includes at least one bedknife carried by the bedknife retainer. The reel mower assembly further includes an engagement device operative to prevent sliding movement of the retainer with respect to the backing while allowing the backing to move away from the magnet when a separating force is exerted on the retainer in a direction away from the retainer that is greater than an attractive force exerted on the retainer by the backing when the retainer is in the operating position.  
         [0009]     Further areas of applicability will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the various embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     This application will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0011]      FIG. 1  is an exploded perspective view of a walk-behind reel mower arranged in accordance with various embodiments;  
         [0012]      FIG. 2  is an exploded perspective view of a reel mower assembly constructed in accordance with various embodiments;  
         [0013]      FIG. 3  is a perspective view of the top of a magnetic bed bar in accordance with some embodiments;  
         [0014]      FIG. 4  is a perspective view of the underside of the bed bar in  FIG. 3 ;  
         [0015]      FIG. 5  is a perspective view of a bedknife for attachment to the magnetic bed bar of  FIG. 3 ;  
         [0016]      FIG. 6  is a schematic view of the bedknife of  FIG. 5  in the operating position on the magnetic bed bar of  FIG. 3 ;  
         [0017]      FIG. 7  is a schematic view of an alternative bedknife in the operating position on the magnetic bed bar of  FIG. 3 ;  
         [0018]      FIG. 8  is a plan view of a bed knife according to a first method of manufacture;  
         [0019]      FIG. 9  is a cross sectional view of the bed knife of  FIG. 8 ;  
         [0020]      FIG. 10  is a plan view of the blank used in forming the bed knife of  FIG. 8 ;  
         [0021]      FIG. 11  is a plan view of the bed knife of  FIG. 8  following multiple grinding operations;  
         [0022]      FIG. 12  is a cross sectional view of the bed knife of  FIG. 11 ;  
         [0023]      FIG. 13  is a plan view of the bed knife of  FIG. 11  following the final grinding operation;  
         [0024]      FIG. 14  is a cross sectional view of the bed knife of  FIG. 13   
         [0025]      FIG. 15  is a plan view of a bed knife according to a second method of manufacture; and  
         [0026]      FIG. 16  is a cross sectional view of the bed knife of  FIG. 15 .  
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0027]     The following description of the embodiments is merely exemplary in nature and is in no way intended to limit the embodiment(s), application, or uses described herein.  
         [0028]      FIG. 1  shows the basic components of a mower  10  constructed in accordance with the various embodiments. Mower  10  is shown as a walk-behind mower; however, mower  10  can be any variety of reel-type greensmower, including single and multiple reel-type mowing devices. Mower  10  includes cutting unit  12 , which comprises a power source or engine  15  coupled to a frame  16 , and a handle  14  coupled to frame  16 . A traction roller  18  is rotatably coupled to frame  16  and drivingly connected to engine  15 . Cutting unit  12  further includes a reel mower assembly  20 , described in detail with respect to  FIGS. 2-5 . A transmission  24  includes a plurality of sprockets  25  selectively transferring rotational output torque of engine  15  to traction roller  18 . Transmission  24  includes a clutch  26  positioned intermediate engine  15  and transmission  24 . Clutch  26  operates in an engaged and disengaged mode for selectively transferring power from engine  15  to traction roller  18 . Wheels  28  are coupled to traction roller  18  and are also selectively driven by engine  15  to provide motive force for translating walk-behind greensmower  10 , typically during a transportation mode of operation.  
         [0029]      FIG. 2  schematically illustrates the major parts of reel mower assembly  20 . Reel mower assembly  20  comprising a mower reel  30  mounted to frame  16  to enable relative rotational movement. Reel mower assembly  20  is commonly found on various types of mowers, including riding mowers and walk-behind mowers. A drive rotates reel  30  about a reel axis A. A magnetic bed bar  32  attaches to frame  16 , and bedknife  34  magnetically attaches to magnetic bed bar  32 . Typically, reel  30  further includes an adjustment mechanism to vary the position of magnetic bed bar  32  with respect to reel  30  in order to provide the proper cutting relationship between bedknife  34  and reel  30 .  
         [0030]      FIGS. 3 and 4  show some embodiments of magnetic bed bar  32  in accordance with some embodiments. Magnetic bed bar  32  includes a plurality of magnets  36 . Magnets  36  are embedded into magnetic bed bar  32  providing a substantially flush surface  38  for connecting bedknife  34 . Bedknife  34  is magnetically maintained against magnets  36  in an operating position through the use of locating pins  40 .  
         [0031]      FIG. 5  illustrates a bedknife  34  constructed in accordance with some embodiments. Bedknife  34  includes a first cutting edge  34 A and a second cutting edge  34 B. Cutting edges  34 A and  34 B are formed on opposite sides of bedknife  34 , allowing only one cutting edge  34 A to be in operation at any time. As cutting edge  34 A dulls, bedknife  34  can be reversed operationally orient the other cutting edge  34 B. After both cutting edges  34 A and  34 B are dulled, bedknife  34  may be removed, discarded, and replaced. Bedknife  34  also includes notches  42  for engaging locating pins  40  of magnetic bed bar  32 . While locating pins  40  and notches  42  are properly aligned, bedknife  34  is not able to slide out of position relative to magnetic bed bar  32 .  
         [0032]      FIG. 6  shows some embodiments of the magnetic bedknife assembly. Bedknife  34  magnetically attaches to magnetic bed bar  32 . Locating pins  40  of bed bar  32  engage notches  42  of bedknife  34  and magnetic backing plate  44  to ensure the proper cutting relationship between bedknife  34  and reel  30 . Magnetic backing plate  44  provides additional magnetic attraction between magnetic bed bar  32  and bedknife  34  to prevent bedknife  34  from disconnecting from bed bar  32 .  
         [0033]     In certain applications, selection of the magnetic backing plate  44  may impact the operation of reel mower assembly  20 . Depending on the length and thickness of the grass, different strength magnetic backing plates  44  may be needed. For example, a weaker magnetic backing plate  44  could be used for cutting the green on a golf course when the grass is shorter and damage to reel mower assembly  20  is less likely. Cutting thick grass may require extra magnetic force to prevent bedknife  34  from disconnecting from magnetic bed bar  32 . This requires a stronger magnetic backing plate  44 . Although additional magnetic force is provided by magnetic backing plate  44 , the magnetic force still allows bedknife  34  to disconnect from magnetic bed bar  32  to prevent damage to reel mower assembly  20 . Magnetic backing plate  44  may be formed from steel, and bedknife  34  is formed from a more flexible material, such as tempered spring steel.  
         [0034]     As depicted in  FIG. 6 , bedknife  34  may be formed from one piece of a material. Alternatively,  FIG. 7  shows a second configuration of the bedknife assembly in accordance with some embodiments.  FIG. 7  includes a magnetic bed bar  32  magnetically attached to magnetic backing plate  44 . Locating pins  40  of magnetic bed bar  32  engage notches  42  formed on magnetic backing plate  44 . This engagement ensures that bedknives  46 A and  46 B are in proper cutting relationship to reel  30 . In the second configuration, a pair of bedknives  46 A and  46 B are bonded to opposite ends of backing plate  44 . Securing bedknives  46 A and  46 B to the magnetic backing plate  44  could be any bonding method, such as gluing or staking.  
         [0035]     As previously stated, first and second bedknives  46 A and  46 B are bonded to magnetic backing plate  44 . Only one bedknife  46 A is necessary, however, if first bedknife  46 A dulls, magnetic backing plate  44  can be reversed to operationally orient second bedknife  46 B to provide a cutting edge. Magnetic backing plate  44  may be formed from steel, and first and second bedknives  46 A and  46 B are formed from a more flexible material, such as tempered spring steel.  
         [0036]     The embodiments described herein could be practiced in a number of fashions including by manufacturing new reel cutting assemblies in accordance with some embodiments, or alternatively, by producing a retrofit bed bar or support frame kit which would allow the magnetic blade attachment of various embodiments to be implemented on an existing mower.  
         [0037]     Additionally, magnetic bed knife  18  of various embodiments could be manufactured according to various manufacturing processes. More particularly, as seen in  FIGS. 8-14 , bed knife  18  may be made of carbon steel, specifically AISI 1566 Hot Rolled Pickled and Oiled steel or other suitable material, which is generally referenced at numeral  100 . Carbon steel bed knife  100 , like bed knife  18 , is adapted to be magnetically held against magnets  20  in an operating position on bed bar  16  as illustrated in  FIG. 6  such that bed knife  100  is oriented in cutting relationship with reel  2  in the same fashion as bed knife  18 .  
         [0038]     With particular reference to  FIGS. 8-14 , the manufacturing steps of carbon steel bed knife  100  will now be discussed in detail. A generally planar blank  101  is first cut to length. Planar blank  101  is then fed through a stamping or pressing machine that first flattens and straightens planar blank  101  and then imparts a bending force upon the blank. Although this shape can vary among reel mowers, the present shape of bed knife  100  includes a generally planar mounting portion  102  and an upturned cutting portion  104 . As best seen in  FIG. 9 , upturned cutting portion  104  initially includes a radius portion  106  interconnecting a distal end  108  with mounting portion  102 . Specifically, as a result of the stamping process used to form carbon steel, radius portion  106  includes an outer surface  110  that, as seen in  FIG. 9 , extends below a lower surface  112  of mounting portion  102 . As should be appreciated by one skilled in the art, this condition of outer surface  110  extending below lower surface  112  is undesirable as it may impede proper turf cutting and/or may contact the ground surface. Furthermore, this condition may further limit the reel mower&#39;s minimum cutting height. Accordingly, it is preferable to grind off this outer surface  110  to define a generally unobstructed lower surface.  
         [0039]     As best seen in  FIGS. 11 and 12 , bed knife  100  is illustrated following completion of a series of grinding operations sufficient to remove outer surface  110  and define a plurality of faces to create a final desired shape. Specifically, as seen in  FIG. 12 , bed knife  100  includes a tournament cut face  114  extending upwardly from lower surface  112  of mounting portion  102 . Preferably, tournament cut face  114  extends upwardly from lower surface  112  at a relative angle of about between 3 degrees and 8 degrees, such as 5 degrees. Tournament cut face  114  transitions into a super tournament cut face  116  that extends further upwardly at a greater inclination of about 8 degrees relative to lower surface  112 . Bed knife  100  includes a front face  118 , which is at generally perpendicular, such as at about 90 degrees relative to lower surface  112 , and a top face  120 , which is at about between about 5 degrees to 15 degrees, such as 8 to 10 degrees relative to lower surface  112 . Front face  118  and top face  120  intersecting at an edge  121 . Tournament cut face  114 , super tournament cut face  116 , front face  118 , and top face  120  are each formed through various grinding operations that requires bed knife  100  to be fed through a milling machine. Following these grinding operations, bed knife  100  is then heat-treated to provide sufficient hardness to reduce the wear of bed knife  100  during operation.  
         [0040]     Referring now to  FIG. 11 , following heat treatment, bed knife  100  further includes a pair of apertures  122  formed through mounting portion  102 . This pair of apertures  122  is used during manufacturing to position bed knife  100  during subsequent grinding operations. Additionally, a second pair of apertures  124  is formed through mounting portion  102 . This second pair of apertures  124  is sized, similar to holes  28 , to receive pegs  26  of bed bar  16 .  
         [0041]     Finally, as seen in  FIGS. 13 and 14 , a final grind of bed knife  100  is completed. Specifically, through a subsequent grinding operation, following heat treatment, top face  120  is finish ground down such that it is about in the range of 3 degrees to 8 degrees, such as at about 5.5 degrees inclined relative to lower surface  112 . Similarly, front face  118  is ground down to create a cutting edge  126  in place of edge  121 . The particular inclination of cutting edge  126  is dependent upon the desired cutting configuration relative to reel  2 .  
         [0042]     Although bed knife  100  provides a number of beneficial cutting properties and prolonged wear, the manufacturing thereof may lead to undesirably high costs and complexity. Therefore, some embodiments provide a method of manufacturing the bed knife which is capable of eliminating many of the grinding steps, heat treatment, and complexity of construction.  
         [0043]     With particular reference to  FIGS. 15 and 16 , a bed knife  200  is illustrated being manufactured from a simplified process. More particularly, bed knife  200  is made of spring steel, specifically C1095 Scaleless Blue-Tempered Spring Steel, ASTM A682, which is hardened to a minimum Rockwell number of about 47 C. Spring steel bed knife  200 , like bed knifes  18  and  100 , is adapted to be magnetically held against magnets  20  in an operating position on bed bar  16  as illustrated in  FIG. 6  such that bed knife  200  is oriented in cutting relationship with reel  2  in the same fashion as bed knife  18 .  
         [0044]     Still referring to  FIGS. 15 and 16 , the manufacturing steps of spring steel bed knife  200  will now be discussed in detail. As will be appreciated, the manufacturing steps of spring steel bed knife  200  are dramatically simplified relative to bed knife  100 , thereby leading to reduced manufacturing complexity and cost. A generally planar blank (not shown) is fed into a cold roll-forming machine that imparts a bending force upon the blank. Preferably, the planar blank is a roll of spring steel that can quickly and easily be shaped in a continuous, uninterrupted process. As best seen in  FIGS. 15 and 16 , the blank is shaped through a series of rollers into a desired shape. Due to the nature of spring steel, this shaping process may require one or more bending and over bending operations to produce the desired final shape.  
         [0045]     Although the final shape can vary among reel mower designs, the present shape of bed knife  200  includes a generally planar mounting portion  202  and an upturned cutting portion  204 . As best seen in  FIG. 16 , upturned cutting portion  204  extends upwardly from mounting portion  202  at a relative angle of about 9 degrees. As can be appreciated from the figures, unlike bed knife  100  that includes downwardly protruding outer surface  110  of radius portion  106  caused during the stamping process, the cold roll forming process of some embodiments does not create such effect, thereby eliminating the need to grind tournament cut face  114  and super tournament cut face  116 . Therefore, the use of spring steel permits the use of roll forming rather than stamping, which eliminates a number of grinding operations, but for a final grind of front face  218  to define a cutting surface.  
         [0046]     As seen in  FIG. 15 , bed knife  200  further includes a pair of apertures  224  are formed through mounting portion  202 . This pair of apertures  224  is sized, similar to holes  28 , to receive pegs  26  of bed bar  16 .  
         [0047]     Spring steel bed knife  200  provides a number of advantages over conventional screw-on bed knives and, even, bed knife  100 . Specifically, bed knife  200 , being made of spring steel, enables it to be made according to a simple cold roll forming technique. This technique, which has not been used before to form magnetic bed knives, dramatically simplifies the manufacturing process, thereby eliminating the need for complex flattening, straightening, forming, grinding, and heat-treating operations.  
         [0048]     The description of the embodiment(s) is merely exemplary in nature and, thus, variations that do not depart from the gist of the various embodiments are intended to be within the scope of the various embodiments. Such variations are not to be regarded as a departure from the spirit and scope of the invention.