LOW-PROFILE GRINDING MACHINE FOR SHARPENING LAWN MOWER CUTTING REELS

Abstract

One example provides a low-profile grinding machine for sharpening a cylindrical cutting reel of a mower unit. The grinding machine includes a grinding wheel driveable in a reciprocating fashion along a grinding axis, and a grinding platform. The grinding platform houses the grinding wheel and includes a bottom side to sit on a ground surface and an opposing upper side. The upper side includes a ramp portion sloping upwardly from the ground surface to enable the mower unit to be pushed or driven from the ground surface onto the upper surface to position the cylindrical cutting reel over the grinding wheel for sharpening, the lawn mower positioned with a rotational axis of the cylindrical cutting reel extending along the grinding axis.

Description

BACKGROUND

Lawn mowers, particularly commercial lawn mowers, often utilize reel-type mowing units which employ cylindrical cutting reels comprising a number of helical blades disposed about a central shaft. To ensure optimal cutting performance, the helical blades of such cutting reels must be regularly sharpened. Commercial grinders have been developed to perform sharpening of cutting reels, where sharpening typically includes a spin grinding process where the cutting reel is spun counter to a grinding wheel to “square off” the end of each helical blade to form a cutting edge. Some types of lawn mowers, particularly those used for field turf, employ large cutting reels (e.g., 42-inches wide). Placing such large cutting reels onto a grinding machine can be cumbersome and potentially dangerous.

For these and other reasons, a need exists for the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a low-profile grinding machine for sharpening lawn mower cutting reels, according to one example of the present application.

FIG. 2 is an exploded view illustrating a low-profile grinding machine for sharpening lawn mower cutting reels, according to one example of the present application.

FIG. 3 is a perspective view illustrating a low-profile grinding machine for sharpening lawn mower cutting reels, according to one example of the present application.

FIG. 4 is a cross-sectional view generally illustrating a low-profile grinding machine having a walk-behind turf mower with a cylinder cutting reel positioned thereon for sharpening, according to one example of the present application.

FIG. 5 is a flow diagram generally describing a process for a low-profile grinding machine to sharpen a lawn mower cutting reel, according to one example of the present disclosure.

FIG. 6 is a perspective view showing portions of a low-profile grinding machine, including a grinding head assembly, according to one example of the present disclosure.

FIG. 7 is an exploded view illustrating a grinding head assembly suitable for use with a low-profile grinding machine, according to one example of the present disclosure.

FIGS. 8A and 8B are perspective views illustrating a low-profile grinding machine having a cassette-type mower unit positioned thereon for sharpening, according to one example 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 examples in which the disclosure may be practiced. It is to be understood that other examples may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims. It is to be understood that features of the various examples described herein may be combined, in part or whole, with each other, unless specifically noted otherwise.

Lawn mowers, particularly commercial lawn mowers, often utilize reel-type mowing units which employ cylindrical cutting reels comprising a number of helical blades disposed about a central shaft. To ensure optimal cutting performance, the helical blades of such cutting reels must be regularly sharpened. Commercial grinders have been developed to perform sharpening of cutting reels, where sharpening typically includes a spin grinding process where the cutting reel is spun counter to a grinding wheel to “square off” the end of each helical blade to form a cutting edge.

Some types of lawn mowers, particularly those used for field turf, such as walk-behind turf mowers, employ large cutting reels (e.g., 42-inches wide). Removing such cutting reels from a mower for sharpening can be difficult and time-consuming, and placing them onto a grinding machine can be cumbersome and potentially dangerous. As a result, a lift system is typically required, which requires additional floor space and adds cost to the grinding system.

As will be described in greater detail herein, according to examples, the present application provides a low-profile, grinding machine for sharpening cylinder reel mowers. In examples, the grinding machine includes a grinding platform which sits on a ground surface (e.g., a concrete floor) and includes a ramp portion that enables a mower unit (e.g., a walk-behind turf mower or cassette time mower unit) to be pushed or driven onto an upper side of the grinding platform for sharpening of the cylindrical cutting reel. The mower is positioned on the grinding platform so that the cylindrical cutting reel is disposed vertically above a grinding wheel, which is disposed within the grinding platform and exposed to the upper side, such that a rotational axis of the cylindrical cutting reel is positioned along a grinding axis along which the grinding wheel is driven in a reciprocating fashion.

As will be described in greater detail below, in accordance with examples of the present disclosure, with the cylindrical cutting reel positioned over the grinding wheel for sharpening, the grinding axis is able to be vertically adjusted be paralleled with a generally cylindrical perimeter surface of the cutting reel so as to provide uniform contact between the cylindrical cutting reel and grinding wheel over a full width of the cutting reel during a sharpening procedure (e.g., a spin-grinding procedure where the grinding wheel is driven back-and-forth in a reciprocating fashion along the grinding axis while the grinding wheel and cutting reel are rotated counter to one another).

In examples, the mower is held in position by one or more stops disposed on the ramp which engage a rear roller of the mower (e.g., a rear drive roller) to prevent the mower from rolling down the ramp, wherein positions of the stops can be adjusted along the length of the ramp, wherein each position corresponds to one or more mower models and positions corresponding lawn mowers with the cutting reel at a suitable location above the grinding wheel axis for sharpening by the grinding wheel. In examples, when a sharpening procedure is completed, the stops are retracted to enable the mower to be backed down the ramp and removed from the grinding machine.

Providing a low-profile grinding machine, in accordance with examples of the present disclosure, greatly simplifies and reduces the time required for sharpening of cylindrical reel lawn mowers, particularly lawn mowers employing a large cutting reel (sometimes referred to as walk-behind turf mowers). A low-profile grinding machine, in accordance with the present disclosure, eliminates the need to removed a cutting reel from the turf mower as well as the need to lift the cutting reel onto a grinding machine, thereby greatly reducing the chance for injuring and reducing the time required to perform a grinding operation, as well as reducing the overall cost of the grinding system (e.g., eliminating the cost of an equipment lift). Furthermore, when not in use, a lawn mower can be parked/stored on the grinding platform such that a low-profile grinding machine, in accordance with the present disclosure, occupies little space beyond space already required for parking/storage of a lawn mower itself.

Although described primarily herein with respect to sharpening large cylindrical cutting reels of walk-behind turf mowers, as further described herein, a low-profile grinding machine in accordance with the present disclosure can also perform spin grinding operations for sharpening cylindrical cutting reels of cassette-type cutting reel mower units without the need to remove the cylindrical cutting reel from the cassette. In such case, the cassette-type mower unit may be rolled onto, or lifted onto, the grinding platform and positioned with the rotational axis of the cutting reel disposed along the grinding axis of the grinding wheel.

FIGS. 1 and 2 respectively illustrate perspective and exploded views of a low-profile grinding machine 30, according to one example of the present disclosure. Grinding machine 30 includes a grinding platform 32 having a bottom side 34 configured to sit on a ground surface (e.g., a concrete floor) and an upper side 36, with grinding platform 32 housing a grinding wheel 38 which is exposed at upper side 36. In one example, upper side 36 of grinding platform 32 includes a central portion 39 including a ramp portion 40 and a table portion 42, where ramp portion 40 slopes upwardly from the ground surface (e.g., at an angle α) to table portion 42 which is parallel to the ground surface. In one example, as illustrated, one or more ramp extensions 41 are removably attached to a front edge of 43 of ramp portion 40 to extend ramp portion 40 to the ground surface. In other examples (not illustrated), ramp portion 40 itself may fully extend to the ground surface without a need for ramp extensions 41. Employing selectively removable ramp extensions 41 enables a footprint of low-profile grinding machine 30 to be reduced when not in use.

In one example, as illustrated, grinding wheel 38 is disposed within a recessed channel 44 extending into grinding platform 32 from top surface 45 of table portion 42 and extending laterally across a width of table portion 42 (in the y-direction) between opposing lateral sides 48 and 49 of central portion 39 of grinding platform 32. In one example, grinding wheel 38 is coupled about a drive shaft 50 via a hub assembly 52 (described in greater detail below) which enables grinding wheel 38 to being driven in a rotating fashion by drive shaft 50 about its longitudinal axis 54, as indicated by rotational arrow 56, and to be driven back-and-forth in a reciprocating fashion along longitudinal axis 54, as indicated by dual directional arrow 58. According to the illustrated example, longitudinal axis 54 represents a grinding axis 60 about which grinding wheel 38 rotates and along which grinding wheel 38 is driven laterally in a reciprocating fashion during a grinding/sharpening procedure.

In one example, as illustrated, opposing ends 62 and 64 of drive shaft 50 are supported by corresponding bearing assemblies 66 and 68 which, in-turn, are mounted to corresponding adjustment arms 70 and 72 on opposing lateral sides 48 and 49 of central portion 39 of grinding platform 32. In one example, adjustment arms 70 and 72 are pivotally mounted to grinding platform 32 via respective pivot mechanisms 74 and 76 which enable adjustment arms 70 and 72 to pivot in the y-z plane and thereby raise and lower drive shaft 50 and grinding wheel 38 in the y-z dimensions (e.g., to raise and lower drive shaft 50 and grinding wheel 38 relative to top surface 45 of table portion 42.

In one example, a grinding motor 80 drives rotation of drive shaft 50 via a pair of pulleys 82, 84 and a drive belt 86, with pulley 54 being coupled to drive shaft 50 at lateral end 62. In one example, a traverse motor 90 is coupled to hub assembly 52 via a traverse belt 92 extending between a pair of pulleys 94 and 96 on opposing lateral sides 48 and 49 of central portion 39 of grinding platform 32. Traverse motor 90 is controllable to move grinding wheel 42, via hub assembly 52, laterally back-and-forth (i.e., in a reciprocating fashion) along drive shaft 50 during a grinding/sharpening procedure.

In other examples, which are not illustrated, grinding wheel 38 may be mounted to a carriage which may be laterally driven in a reciprocating fashion along a guide shaft, where rotation of the grinding wheel is independent from the guide shaft. In addition to that explicitly illustrated and mentioned herein, it is noted that any number of suitable implementations may be employed for providing lateral movement of grinding wheel 38.

In one example, grinding machine 30 includes a pair of control towers 100 and 102 disposed on opposing lateral sides 48 and 49 of central portion 39 of grinding platform 32 and which include mechanical and electrical controls for controlling the operation of grinding machine 30. In one example, control towers 100 and 102 respectively include handwheels 104 and 106 for adjusting the vertical position (i.e., in the z-direction) of respective opposing lateral ends 62 and 64 of drive shaft 50 via adjustment of corresponding adjustment arms 70 and 72. In one example, handwheels 104 and 106 are in mechanical communication with corresponding adjustment arms 70 and 72 via respective spindles 108 and 110.

In one example, each control tower 100 and 102 includes a corresponding electronic user interface 112 and 114 to control various aspects of the operation of grinding machine 30, via a controller 115, such as turning the power on/off, control of grinding motor 80 and traverse motor 90, and control of spin drive motor 142 (e.g., see FIG. 3). In other examples, grinding machine 30 may include a single control tower 100. In some examples, grinding towers 100 and 102 may be positioned at locations, such as on opposing lateral sides of ramp portion 40 rather than on opposing lateral sides of table portion 42. In other examples, in lieu of handwheels 104 and 106 can corresponding spindles 108 and 110, grinding machine 30 may employ servo motors controlled via electronic user interface(s) 110/112 to control the vertical position of opposing ends 62 and 64 of drive shaft 50 via adjustment arms 70 and 72. It is noted that any number of suitable approaches other than use of adjustment arms 70 and 72 may be employed to adjust the vertical positioning of drive shaft 50, such as servo motors or hydraulic actuators (e.g., pistons) which may vertically adjust the positions of opposing ends 62 and 64 of drive shaft 50.

In one example, grinding machine 30 includes one or more stops 120 which are disposed on ramp portion 40 and a moveable between an extended position above an upper surface 47 of ramp portion 40, and a retracted position where stops 100 are flush with or below upper surface 47. In one example, the positioning of stops 120 between the extended and retracted positions is controllable via a mechanical toggle switch 122 (e.g., a foot switch) disposed on front edge 43 of ramp portion 40. In other examples, toggle switch 122 may be a rotary pivot switch where rotation in a first direction (e.g., clockwise) causes stops 120 to be placed in the extended position, and rotation in a second direction (e.g., counter-clockwise) causes stops 120 to be placed in the retracted position.

In one example, as will be described in greater detail below (e.g., see FIG. 4), when in the extended position, when a force is applied to stops 120 in a loading direction 124, such as when driving a lawn mower onto grinding platform 32, stops 120 pivot downward so as to be flush with upper surface 47 of ramp portion 40 to enable the lawn mower to pass there over. Once the lawn mower has passed over stops 120 in a loading direction 124 (i.e., in the y-direction from front edge 43 toward table portion 42), stops 120 return to the extended position (e.g., stops may be spring loaded) and prevent the lawn mower from rolling down ramp portion 40 in an unloading direction 126 (i.e., in the y-direction from table portion 42 toward front edge 43). In examples, stops 120 contact a driven rear drum of a lawn mower to prevent movement of the lawn down ramp portion 40 in unload direction 126 (e.g., see FIG. 4 below). When toggled to the retracted position, stops 120 pivot upward downward from the extended position above upper surface 47 of ramp portion 40 to the retracted position where stops 120 are flush with or below upper surface 47.

It is noted that when a lawn mower has been loaded (disposed) on grinding platform 32 with the driven rear drum of the lawn mower in contact with stops 120 to prevent movement of the lawn mower in the unload direction 126, if toggle switch 122 is operated (either purposely or by accident) to actuate stops 120 from the extended position to the retracted position, stops 120 are configured to remain in the extended position due to a force applied to stops 120 by the rear drum of the lawn mower. In such case, for stops 120 to pivot from the extended position to the retracted position, the lawn mower must first be moved incrementally in loading direction 124 to so that the driven rear drum of the mower no longer contacts stops 120, at which point stops 120 will pivot to the retracted position and allow the lawn mower to be unloaded from grinding platform 32.

In examples, grinding machine 30 further includes a front clamping assembly 130 which is moveable back-and-forth and loading and unloading directions 124 and 126 within a slot 132 in table portion 42, and is configured to clamp to a front roller of a lawn mower when positioned on grinding platform 32.

FIG. 3 is a perspective view illustrating another example of low-profile grinding machine 30, according to the present disclosure. As illustrated by FIG. 3, grinding machine 30 further includes a spin drive assembly 140 including a spin drive motor 142 connected to an adjustment arm 144 comprising a first arm segment 146, a second arm segment 147, and a third arm segment 148. First arm segment 146 is pivotally coupled to control tower 102 via a pivot bracket 149, second arm segment is fixedly mounted to first arm segment 147, third arm segment 148 is slideably coupled to second arm segment 147, and spin drive motor 146 is slideably coupled to third arm segment 148. Via sliding movement of spin drive motor 146 along second and third arm segments 147 and 147, and rotational movement of first arm segment 146 within pivot bracket 149, a position of drive shaft 150 of spin drive motor 142 can be 3-dimensionally adjusted to enable alignment with, and connection to, a drive shaft of the cylindrical cutting reel of a lawn mower when disposed on grinding platform 32 for sharpening.

During a sharpening procedure, drive shaft 150 of spin drive motor 142 is coupled to and spins the cylindrical cutting reel in a direction counter to that of grinding wheel 38. In examples, as described in greater detail below, spin drive motor 142 is controllable to spin the cylindrical cutting reel at a low-speed and low-torque during an alignment procedure of the cylindrical cutting reel with grinding wheel 38, and to spin the cylindrical cutting reel at a higher-speed and higher torque during a spin-grinding procedure. In one example, as illustrated by FIG. 3, each control tower 100 and 102 includes a pivot bracket 149 so that spin drive assembly 140 can be mounted on either lateral side of grinding platform 132.

FIG. 3 further illustrates another example implementation of stops 120, where stops 120 are positioned between locations of ramp extensions 41 rather than in-line with ramp extensions 41 (see FIGS. 1 and 2). Additionally, the positions of stops 120 in loading and unloading directions 124 and 126 between front edge 43 and recessed channel 44 are adjustable via a number of selectable positions along positioning racks 152. In one example, stops are adjustable at predetermined intervals (e.g., ½ inch intervals) over an adjustment range (e.g., an 8-inch range). Such adjustability enables stops 120 to be moved to different positions for different models of lawn mowers so that when the driven rear roller of a given lawn mower is resting against stops 120 the cylindrical cutting reel is positioned at a suitable location over channel 44 and grinding wheel 38 for sharpening.

FIG. 4 is a cross-sectional view generally illustrating an example of grinding machine 30 having a lawn mower 160 employing a cylinder cutting reel 162 positioned on grinding platform 32 for sharpening on grinding platform 32. In the illustrated example, lawn mower 160 comprises a self-propelled mower having a driven rear drive roller 164 (e.g., driven by a gas engine) to propel lawn mower 160, a front roller 166, with cylindrical cutting reel 162 positioned there between, and a bed knife 168 which forms a sheer point with cylindrical cutting reel 162 for cutting.

To perform a sharpening operation of cylindrical cutting reel 162, lawn mower 160 is driven up ramp portion 40, including ramp extensions 41, in loading direction 124 with stops 120 being in the extended position. As front roller 166, cutting reel 162, and driven rear roller 164, along with other components of lawn mower 160, are driven up ramp portion 40, stops 120 are pressed down to be flush with upper surface 47 to enable lawn mower 60 to be driven in loading direction 124. Upon driven rear roller 164 passing stop 120 in loading direction 124, stop 120 returns to the extended position above surface 47 and lawn mower 160 is allowed to roll slightly down ramp portion 40 in unloading direction 126 until rear roller contacts and is stopped by stop 120.

In one example, as illustrated, stops 120 is disposed at a position along ramp portion 40 so that when stop 120 is contacting rear roller 164 to hold lawn mower 160 in position for sharpening, front roller 166 is resting on top surface 45 of table portion 42, and a leading edge of bed knife 168 is disposed along an edge of recessed channel 44 with cylindrical cutting reel 162 disposed above grinding wheel 38.

Because a distance, D1, between a leading edge of bed knife 168 and contact point of the rear roller 164 with stop 120 may vary between different lawn mowers (e.g., between different makes and models, and variations between a same model having different set-ups), according to examples, a position of stop 120 along ramp portion 40 may be selectively adjusted via positioning racks 152. In one example, positioning racks 152 include a number of positioning notches 153 to which stops 120 can be selectively positioned so that stop 120 can be adjusted to position a leading edge of bed knife 168 along recessed channel 44 and cutting reel 162 at a desired location above grinding wheel 38 for lawn mowers 160 having arrangements (including different distances, D1). Once lawn mower 160 is positioned on grinding platform 32 with cylindrical cutting reel 162 suitably positioned above grinding wheel 38, a grinding/sharpening operation can be performed.

FIG. 5 is a flow diagram generally describing an example sharpening process 200 of grinding machine 30 for sharpening a cylindrical cutting reel of a lawn mower, such as lawn mower 160. In one example, process 200 begins with a loading procedure 201 to position lawn mower 160 on grinding platform 32 for sharpening. At 202, loading procedure 201 includes vertically positioning grinding wheel 38 and drive shaft 50 within recessed channel 44 (e.g., via handwheels 104 and 104) so that grinding wheel 38 is disposed below top surface 45 of table portion 42. At 204, loading procedure 201 includes moving (e.g., driving) a lawn mower, such as lawn mower 160, up ramp portion 40, with stops 120 in the extended position. After rear roller 164 has moved past stops 120 in loading direction 124, lawn mower 160 is allowed to roll down ramp portion 40 in unloading direction 126 until rear roller 164 is engaged by stops 120 which prevent further movement of lawn mower 160 down ramp portion 40 and positions lawn mower 160 with bed knife 168 disposed along a forward edge of recessed channel 44 and cylindrical cutting reel 162 is disposed at suitable grinding location over grinding wheel 38 and drive shaft 50 positioned within recessed channel 44. In one example, at 203, loading procedure 201 further includes positioning stops 120 at a selected position 153 on positioning rack 150 that corresponds to the type and characteristics of the lawn mower 160 (e.g., make/model) to be sharpened.

After lawn mower 160 has been loaded onto grinding platform 32, process 200 includes a setup procedure 206 which is performed to align and parallel grinding wheel 38 and drive shaft 50 with a perimeter surface of cylindrical cutting reel 162. In one example, set-up procedure 206, at 208, includes coupling drive shaft 150 of spin drive motor 142 to a drive shaft of cylindrical cutting reel 162. Subsequently, at 210, set-up procedure 206 includes activating spin drive motor 142, such as via user interface 112/114 and controller 115, to spin cutting reel 162 in a low-rpm, low-torque grinder setup mode.

At 212, setup procedure 206 includes positioning grinding wheel 38 along grinding axis 60 at one end of cutting reel 162 and, at 214, upwardly adjusting a vertical position of grinding wheel 38, such as via hand wheel 104 and adjustment arm 70, until grinding wheel 38 contacts cylindrical cutting reel 162 (at which point cutting reel 162 may stop spinning due to the low torque being applied by spin drive motor 142). At 216, upon contacting the cylindrical cutting reel 162, setup procedure 206 includes lowering grinding wheel 38 by a predetermined amount, such as by a ½ turn of handwheel 104, to space grinding wheel 38 from the cylindrical cutting reel 162 by an incremental distance.

At 218, setup procedure 206 includes positioning grinding wheel 38 along grinding axis 60 at the opposite end of cutting reel 162 and, at 220, upwardly adjusting a vertical position of grinding wheel 38, such as via hand wheel 106 and adjustment arm 70, until grinding wheel 38 contacts cylindrical cutting reel 162 (at which point cutting reel 162 may stop spinning due to the low torque being applied by spin drive motor 142). At 222, upon contacting the cylindrical cutting reel 162, setup procedure 206 includes lowering grinding wheel 38 by the predetermined amount, such as by a ½ turn of handwheel 106, to space grinding wheel 38 from the opposite end of cylindrical cutting reel 162 by the incremental distance. By lowering grinding wheel 38 by a same incremental distance from each end of cylindrical cutting reel 162, such as by a ½ turn of handwheels 104 and 106, drive shaft 50 and, thus, grinding wheel 38 and grinding axis 60 are in parallel with the perimeter surface of cylindrical cutting reel 162.

After completing setup procedure 206, process 200 includes performing a grinding procedure 224. At 226, grinding procedure 224 includes placing grinding machine 30 into a grinding mode via user interface 112/114 and controller 115, wherein grinding mode includes activating grinding motor 80 to spin drive shaft 50 and grinding wheel 38, and to place spin drive motor 142 into a higher rpm and higher torque mode. At 228, grinding procedure 224 includes raising the vertical position of opposing ends of drive shaft 50 by a same incremental amount via handwheels 104 and 106 (e.g., a same number of turns) to make contact between grinding wheel 38 and the perimeter surface of cylindrical cutting reel 162.

At 230, grinding procedure 224, via user interface 112/114 and controller 115, includes activating traverse motor 90 to begin reciprocating movement of grinding wheel 38 back and forth along drive shaft 50 (i.e., along grinding axis 60). Thereafter, at 232, grinding procedure 224 includes adjusting handwheels 104 and 106 to adjust the vertical height of each end of drive shaft 50 to provide uniform contact between grinding wheel 38 and the perimeter surface of cylindrical cutting reel 162 across the full length thereof as grinding wheel 38 traverses back-and-forth along grinding axis 60. Additional vertical adjustments of drive shaft 50 can be made thereafter to grind/sharpen cylindrical cutting reel 162 as desired.

After completion of grinding procedure 224, grinding and traverse motors 80 and 90 are powered down, grinding wheel 38 is lowered (such as via handwheels 104 and 106) to be below upper surface 45 of table portion 42, stops 120 are placed into the retracted position (such a via toggle switch 122), and lawn mower 160 is backed down ramp portion 40 onto the ground surface to be removed from grinding machine 30. Alternatively, lawn mower 160 may remain of base platform 32 for storage with stops 120 remaining in the extended position.

FIGS. 6 and 7 below generally illustrate and describe a grinding head assembly 250, including grinding wheel 38 and hub assembly 52, to slideably connect grinding wheel 38 to drive shaft 50, according to examples of the present disclosure. FIG. 6 is a perspective view showing portions of grinding platform 32 of driven-on grinding machine 30 and illustrating grinding head assembly 250 mounted to drive shaft 50, according to one example. FIG. 7 is an exploded view illustrating grinding head assembly 250, according to one example.

Referring to FIG. 6, hub assembly 52 is rotatably and slideably coupled about drive shaft 50, with grinding wheel 38 being fixedly attached to hub assembly 52. In-turn, hub assembly 52 is rotatably coupled to a traverse mount assembly 252, with traverse mount assembly 252 being fixedly coupled to traverse belt 92 (see also FIG. 2). As described below, according to such arrangement, grinding wheel 32 is configured to rotate with drive shaft 50 while simultaneously being driven along a length of drive shaft 50 via traverse mount assembly 252.

Referring to FIG. 7, hub assembly 52 includes a spin hub 260 having a threaded first end 262, an opposing second end 264, and a wheel flange 266 disposed therebetween about an outer circumference of spin hub 260. Spin hub 260 extends through a central hub opening 270 of grinding wheel 38, with grinding wheel 38 being coupled to spin hub 260 via a spin flange nut 272 which threads onto threaded first end 262 of spin hub 260 to compressively sandwich grinding wheel 38 between spin flange nut 272 and wheel flange 266.

Traverse mount assembly 252 includes a traverse arm 280, a bearing assembly 282, and a traverse bracket 284. Bearing assembly 282 is coupled about second end 264 of spin hub 260, with bearing assembly 280 being retained within a bearing retainer channel 286 of traverse arm 280, such that grinding wheel 38, spin hub 260, and spin flange nut 272 are able to rotate/spin relative to traverse arm 280 and bearing assembly 282. Drive shaft 50 extends through hub assembly 52 (e.g., spin hub 260 and spin flange nut 272), and through traverse arm 280 and bearing assembly 282, with a key tab 290 disposed on an inner circumferential surface of spin hub 260 to slideably insert and ride within a corresponding key slot 292 that extends longitudinally along the length of drive shaft 50 (see FIG. 6). With key tab 290 disposed within key slot 292, grinding wheel 38 and hub assembly 252 can be rotatably driven by drive shaft 50 (via operation of grinding motor 80, see FIG. 2) while being laterally moved along the length of drive shaft 50 via traverse mount assembly 280 (via traverse motor 90 and traverse belt 92, see FIG. 2).

It is noted that grinding head assembly 250, in particular, hub assembly 52 and traverse mount assembly 252 employing bearing assembly 282, eliminates the use of brass pads and/or brass forks for lateral movement of a grinding wheel along a drive shaft, where such pads and forks wear significantly over time and allow the grinding wheel to bounce and vibrate on the drive shaft (which reduces reliability of cutting reel sharpening).

Although described above primarily with respect to sharpening large cylindrical cutting reels of walk-behind turf mowers, a low-profile grinding machine 30, in accordance with the present disclosure, can also perform spin grinding operations for sharpening cylindrical cutting reels of other types of lawn mowers, such as cassette-type mower units employing cylindrical cutting reels.

FIGS. 8A and 8B illustrate perspective views of one example of a low-profile grinding machine 30 having a cassette-type mower unit 360 employing a cylindrical cutting reel positioned on grinding platform 32. In FIGS. 8A and 8B, it is noted that grinding machine 30 is illustrated without ramp extensions 41 (e.g., see FIGS. 1 and 2) being coupled to ramp portion 40 of grinding platform 32.

As illustrated, cassette-type mower unit 360 includes a chassis 362 to which is mounted a rear roller 364 (FIG. 8A), a front roller 366, and a cylindrical cutting reel 368 disposed therebetween and disposed within a housing 370 (FIG. 8B). One or more such cassette-type mower units 360 are configured to be selectively attached to corresponding lawn mowers and to be readily removable to enable sharpening of cylindrical cutting reel 368. As described herein, low-profile grinding machine 30, in accordance with the present disclosure, enables spin-grinding sharpening procedures to be carried out on cylindrical cutting reel 368 without the need to remove cutting reel 368 from cassette 360.

In examples, cassette mower unit 360 may be rolled onto grinding platform 32 via ramp portion 40 and ramp extensions 41 (not illustrated), or be lifted onto grinding platform 32, and positioned with cutting reel 368 disposed over recessed channel 44 and above grinding wheel 38 (see FIG. 1). In examples, as illustrated, cassette mower unit 360 is positioned with rear roller 364 disposed on ramp portion 40, with stops 120 in an extended position to prevent cassette mower unit 360 from rolling down ramp portion 40 and disposed at a location along ramp portion 40 to position cutting reel 368 over recessed channel 44 with front roller 366 disposed on table portion 42 and clamped in place via front clamping assembly 130.

In some examples, if stops 120 are unable to be positioned as a location along ramp portion 40 which disposes cutting reel 368 at a desired location above grinding wheel 38 (e.g., if there is no corresponding positioning notch 153, see FIG. 4), a rear clamping assembly (not shown), similar to front clamping assembly 130, may be disposed within a rear clamping slot 372 to engage and hold rear roller 364 of cassette mower unit 360 at a desired location along ramp portion 40. Once loaded onto grinding platform 32, a grinding process similar to that described above by FIG. 5 may be performed to sharpen cutting reel 360.

Although specific examples have been illustrated and described herein, a variety of alternate and/or equivalent implementations may be substituted for the specific examples shown and described without departing from the scope of the present disclosure. 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. This application is intended to cover any adaptations or variations of the specific examples discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims

1. A low-profile grinding machine for sharpening a cylindrical cutting reel of a mower unit, the grinding machine comprising: a grinding wheel driveable in a reciprocating fashion along a grinding axis; anda grinding platform housing the grinding wheel, the housing including: a bottom side to sit on a ground surface; andan upper side including a ramp portion sloping upwardly from the ground surface to enable the mower unit to be pushed or driven from the ground surface onto the upper surface to position the cylindrical cutting reel over the grinding wheel for sharpening with a rotational axis of the cylindrical cutting reel extending along the grinding axis.

2. The low-profile grinding machine of claim 1, wherein the mower unit comprises a walk-behind turf mower.

3. The low-profile grinding machine of claim 1, wherein the mower unit comprises a cassette-type mower unit.

4. The low-profile grinding machine of claim 1, wherein the grinding wheel and grinding axis are exposed to the upper side of the grinding platform.

5. The low-profile grinding machine of claim 1, including a grinding wheel positioning system to adjust a position of the grinding axis to parallel the grinding wheel with a perimeter surface of the cylindrical cutting reel when the mower unit is positioned on the grinding machine.

6. The low-profile grinding machine of claim 5, further including: a drive shaft driveable about a longitudinal axis of rotation, the grinding wheel coupled about a circumference of the drive shaft such that the longitudinal axis of rotation of the drive shaft is the grinding axis, the grinding wheel coupled about the drive shaft to be rotatable with the drive shaft and to be moveable laterally along the axis of rotation.

7. The low-profile grinding machine of claim 6, the grinding wheel positioning system to adjust the position of the grinding axis by adjusting a position of the drive shaft, the grinding wheel positioning system comprising a pair of handwheels, each handwheel in mechanical communication with a corresponding one of the opposing lateral ends of the drive shaft, wherein each handwheel adjusts the vertical position of the corresponding one of the opposing ends of the drive shaft.

8. The low-profile grinding machine of claim 7, wherein the grinding wheel is coupled to the drive shaft via a hub assembly, the hub assembly comprising: a tubular spin hub extending between a first end and a second end and defining an external circumferential surface and an internal circumferential surface, and including a key tab disposed on the internal circumferential surface, the grinding wheel fixedly coupled about the external circumferential surface between the first end and the second end;a ring-shaped bearing assembly connected about the external circumferential surface at the second end of the spin hub;a traverse arm having a circular bearing retainer disposed about a circular opening through the traverse arm, the bearing assembly retained within the bearing retainer so that the spin hub spins relative to the traverse arm.

9. The low-profile grinding machine of claim 8, the external circumference surface of the spin hub being threaded at the first end, and the spin hub including a flange extending about the external circumferential surface between the first and second end, the hub assembly further including a nut to thread onto the first end and compress the grinding wheel between the nut and the flange to couple the grinding wheel to the spin hub.

10. The low-profile grinding machine of claim 8, wherein the drive shaft includes a linear key slot extending laterally between the opposing lateral ends of the drive shaft, wherein the drive shaft extends through the circular opening of the traverse arm, through the ring-shaped bearing assembly, and through the spin hub with the key tab being slideably disposed within linear key slot such that the spin hub and grinding wheel spin with the drive shaft about the grinding axis, and move together with the traverse arm laterally along the grinding axis between the opposing lateral ends of the drive shaft.

11. The low-profile grinding machine of claim 10, including a traverse drive system to drive the traverse arm laterally along the drive shaft.

12. The low-profile grinding machine of claim 11, the traverse drive system including a drive belt coupled to the traverse arm which is controllably driven to move the traverse arm, together with the spin hub and grinding wheel, in a reciprocating fashion along the grinding axis.

13. The low-profile grinding machine of claim 1, including a spin drive motor to connect to the rotational axis of the cylindrical cutting reel and controllable to spin the cylindrical cutting reel according to a plurality of selectable modes including a low-rpm, low-torque setup mode, and a high-rpm, high-torque grinding mode.

14. The low-profile grinding machine of claim 1, further including: a stop disposed along the ramp portion, the stop operable between an extended position, where the stop is positioned to extend above an upper surface of the ramp portion, and a retracted position, where the stop is flush with or below the upper surface of the ramp portion.

15. The low-profile grinding machine of claim 14, when the stop is in the extended position, the stop to pivot to the retracted position in response to a force being applied in an upward direction of the ramp portion and biased to return to the extended position in response to the force being removed.

16. The low-profile grinding machine of claim 14, when a mower unit is disposed on the grinding platform for sharpening, the stop, when in the extended position, to engage a rear roller of the mower unit to prevent the mower unit from rolling down the ramp, the stop disposed at a location along the ramp portion between a bottom of the ramp portion and top of the ramp portion to position the cylindrical cutting reel over the grinding wheel for sharpening with a rotational axis of the cylindrical cutting reel extending along the grinding axis.

17. The low-profile grinding machine of claim 16, wherein a location of the stop is adjustable along the ramp portion in a direction extending between a bottom of the ramp portion and a top of the ramp portion.

18. A grinding machine for sharpening cylindrical cutting reels of lawn mowers, the grinding machine comprising: a grinding wheel;a drive shaft extending longitudinally between opposing lateral ends, a longitudinal axis of rotation of the drive shaft representing a grinding axis; anda hub assembly coupling the grinding wheel about the drive shaft, the hub assembly comprising: a tubular spin hub extending between a first end and a second end and defining an external circumferential surface and an internal circumferential surface, and including a key tab disposed on the internal circumferential surface, the grinding wheel fixedly coupled about the external circumferential surface between the first end and the second end;a ring-shaped bearing assembly connected about the external circumferential surface at the second end of the spin hub;a traverse arm having a circular bearing retainer disposed about a circular opening through the traverse arm, the bearing assembly retained within the bearing retainer so that the spin hub spins relative to the traverse arm.

19. The grinding machine of claim 18, the external circumference surface of the spin hub being threaded at the first end, and the spin hub including a flange extending about the external circumferential surface between the first and second end, the hub assembly further including a nut to thread onto the first end and compress the grinding wheel between the nut and the flange to couple the grinding wheel to the spin hub.

20. The grinding machine of claim 18, wherein the drive shaft includes a linear key slot extending laterally between the opposing lateral ends of the drive shaft, wherein the drive shaft extends through the circular opening of the traverse arm, through the ring-shaped bearing assembly, and through the spin hub with the key tab being slideably disposed within linear key slot such that the spin hub and grinding wheel spin with the drive shaft about the grinding axis, and move together with the traverse arm laterally along the grinding axis between the opposing lateral ends of the drive shaft.

21. The grinding machine of claim 20, including a traverse drive system including a drive belt coupled to the traverse arm which is controllably driven to move the traverse arm, together with the spin hub and grinding wheel, in a reciprocating fashion along the drive shaft between the opposing first and second ends.

22. A drive-on grinding machine for sharpening a cylindrical cutting reel of a lawn mower, the grinding machine comprising: a grinding platform having a bottom major surface to sit on a ground surface and an opposing upper major surface, the grinding platform housing a grinding wheel exposed from the upper major surface, the upper major surface including a ramp portion to facilitate the lawn mower to be pushed or driven from the ground surface onto the upper major surface to position the cylindrical cutting reel over the grinding wheel for sharpening.