Abstract:
A rotating cutting head includes multiple, separate, spaced-apart, parallel loops of chainsaw chains positioned around a central hub. The hub is attached to a spindle of a lawn edger. A safety shield is provided adjacent to the rotating cutting head. As the cutting head rotates, the chainsaw chains cut the tree roots. The rotating cutting head is used for resurfacing exposed tree roots to avoid tripping hazards and tree root strike damage to residential and commercial lawn maintenance equipment.

Description:
RELATED APPLICATION 
     This application is a continuation in part and claims the benefit of priority of U.S. Nonprovisional application Ser. No. 13/068,568 filed on May 16, 2011, which is a nonprovisional and claims the benefit of priority of U.S. Provisional Patent Application No. 61/396,594 filed on Jun. 1, 2010, the entire contents of which are incorporated herein by this reference and made a part hereof. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to landscaping, and, more particularly, to root resurfacing attachment for gasoline powered edgers. 
     BACKGROUND 
     When professionals such as landscapers; golf course maintenance crews; lawn maintenance and property managers, as well as individual homeowners attempt to cut the grass and maintain their lawns; they often encounter tree roots and even cypress knees that protrude above of soil level. If a homeowner or professional attempts to use lawn mowing equipment over the exposed root, the chances are great that the spinning blade of the equipment will end up striking the protruding root and sustain substantial damage to one or more of the mower blade, spindle shaft, deck housing or even the motor. Tree root strike damage could render the equipment totally inoperable. The cost of repairs and or replacement could be substantial. 
     Managers of golf course greens, public parks and recreational areas are able to resurface exposed tree roots that have become tripping hazards to prevent or avoid possible lawsuits from injured parties. However, most homeowners and small commercial landscapers lack an appropriate tool for conveniently resurfacing a root. Many who encounter roots are tempted to inappropriately use the tip of a chain saw for resurfacing. However, this is highly inappropriate chain saw use and risks kickback damage to the saw and injury to the user. 
     Several types of gas powered edging devices are currently available for residential and profession use. Unfortunately, these devices are not well suited for grinding down (i.e., resurfacing) protruding tree roots. When such devices are used to resurface a root, surrounding soil severely dulls and eventually destroys the cutting edges of the blade. 
     U.S. Pat. No. 4,924,571 to Albertson describes a cutting tool suitable for girdling a tree and cutting through tree branches and small tree trunks. The cutting tool is frustoconical in shape and has a single length of chainsaw chain wrapped in a spiral groove around the outside face of frustoconical body. A steel pin secures the one end of the chain to the body. The opposite end is maintained using an adjustment screw and an adjustment cylinder. The frustoconical shape results in different cutting speeds at different axial locations. 
     Additionally, to achieve cutting throughout the axial length, the Albertson device must be tilted. However, because of the different speeds, such a device has a strong tendency to travel in a circular path, making stabilization extremely difficult. Another problem is inevitable loosening of the chain. The pin and screw in Albertson are prone to failure, as they are subjected to considerable impacts and stresses during operation. If either end becomes free, the device is extremely dangerous and self-destructive. If both ends become free, the chain becomes a dangerous projectile. 
     Another problem is that the Albertson device does not allow adjacent rows of saw teeth to be positioned in a preferred arrangement. The chain configuration and geometry of the frustoconical body determine the arrangement of adjacent rows of saw teeth. Thus two right angled teeth may be adjacent to one another resulting in an uneven cutting path. Moreover, the saw teeth are traveling at a less than optimal angled path, rather than a straight path. Chain saw blades are designed to cut when moving in a straight path. The angled path exaggerates or diminishes cutting angles of the toothed blades relative the cutting surface. The angled arrangement also tends to urge the chain laterally off the sprocket. 
     Yet another problem with the Albertson device is that one damaged tooth may require replacement of the entire length of chain. Frequently one tooth is damaged upon encountering a small stone. 
     The invention is directed to overcoming one or more of the problems and solving one or more of the needs as set forth above. 
     SUMMARY OF THE INVENTION 
     To solve one or more of the problems set forth above, in an exemplary implementation of the invention, a root resurfacing attachment for a landscaping edger has a rotating threaded spindle, the root resurfacing attachment includes a rotating hub. The rotating hub includes an axial core with an inboard end and an opposite outboard end, an inboard flange with a first outer diameter at the inboard end, a plurality of evenly spaced ribs extending radially from the axial core, a central bushing channel with a noncircular cross section extending from the inboard flange into the axial core, and a central flange channel extending from the outboard end of the axial core to the central bushing channel. The ribs define a second outer diameter. A removable outboard flange assembly attaches to the outboard end of the rotating hub. The outboard flange assembly has a third outer diameter. An outboard flange attachment such as a threaded bolt or screw attaches the removable outboard flange assembly to the outboard end of the rotating hub. An inboard spindle bushing has a noncircular cross section sleeve configured to fit snugly in the central bushing channel, and a central threaded channel extending axially through the inboard spindle bushing and being threaded to threadedly engage the rotating threaded spindle of the landscaping edger. A plurality of parallel spaced-apart endless cutting chain loops are provided on the hub. Each cutting chain loop has an inner periphery and inner diameter, an outer periphery and outer diameter. Each cutting chain loop comprises an endless loop of connected chainsaw chain links, including a plurality of cutting links, drive links, and tie straps. Each cutting link includes a cutting surface at the outer periphery. Each drive link includes a rib engaging fin at the inner periphery. A plurality of spaced-apart spacer rings keep the adjacent cutting chain loops separated without interfering with cutting. Each spacer ring has an inner periphery and inner diameter, an outer periphery and outer diameter, and a width. Each spacer ring is disposed between adjacent cutting chain loops. The outer diameter of the spacer rings is less than the outer diameter of the cutting chain loops, so that the spacer rings do not interfere with cutting. The inner diameter of the spacer rings allows the spacer rings to slide onto the rotating hub. The first outer diameter is greater than the second outer diameter and the third outer diameter is greater than the second outer diameter. 
     The outboard flange attachment may comprise a bolt with a threaded shank configured to extend through the central flange channel and threadedly into the inboard spindle bushing within the central bushing channel. 
     The plurality of evenly spaced ribs extending radially from the axial core of the hub define a plurality of grooves, including one groove between each adjacent pair of evenly spaced ribs. The rib engaging fin of each drive link is shaped and sized to extend into one of the grooves between each adjacent pair of evenly spaced ribs. The grooves may be curved and include features such as protuberances, which mates with and corresponds to complementary features in the fins. Thus the drive links may be configured to be driven in one rotational direction for cutting. 
     Each cutting surface of each cutting link may comprise a top plate, cutting corner, heel, gullet, side plate, depth gauge, toe, and rivet holes. The plurality of cutting links includes right-hand cutters and left-hand cutters. Each of the cutting links has a cantilevered top plate with a free end. Cutting links on adjacent cutting chain loops may be aligned. In such case, the width of spacer ring is sufficient to prevent cutting links from contacting an adjacent cutting chain loop. 
     A shield assembly may be disposed between the rotating hub and a user. A connecting arm assembly attaches the shield assembly to a shaft of the landscaping edger. The shield assembly may include a base to which the connecting arm assembly attaches and a skirt extending downwardly from the base. The connecting arm assembly may be a one-piece arm or a multi-piece jointed arm. A forked end clamps the shaft of the landscaping edger. 
     A landscaping tool equipped with such a root resurfacing attachment may be used to efficiently grind exposed roots. The grinding occurs substantially evenly along the axial length of hub. A single chain loop may be replaced as needed. There chain loops have no free ends that may come loose. A shield protects a user from flying debris. The action of the chainsaw teeth of the cutting head, rotating clockwise at about 1000 to 4000 rpm, cuts, grinds down or resurfaces the protruding tree roots to the soil level very efficiently. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other aspects, objects, features and advantages of the invention will become better understood with reference to the following description, appended claims, and accompanying drawings, where: 
         FIG. 1  is a perspective view of an exemplary assembled root resurfacing attachment according to principles of the invention; and 
         FIG. 2  is another perspective view of an exemplary assembled root resurfacing attachment according to principles of the invention; and 
         FIG. 3  is an exploded perspective view of an exemplary root resurfacing attachment according to principles of the invention; and 
         FIG. 4  is another perspective view of an exemplary assembled root resurfacing attachment according to principles of the invention; and 
         FIG. 5  is profile view of an exemplary endless chainsaw chain for a root resurfacing attachment according to principles of the invention; and 
         FIG. 6  is perspective view of an exemplary link for a chainsaw chain for a root resurfacing attachment according to principles of the invention; and 
         FIG. 7  is perspective view of a plurality of exemplary links for a chainsaw chain for a root resurfacing attachment according to principles of the invention; and 
         FIG. 8  is an outboard view of an exemplary drive hub for a root resurfacing attachment according to principles of the invention; and 
         FIG. 9  is section view of an exemplary drive hub for a root resurfacing attachment according to principles of the invention; and 
         FIG. 10  is a side view of an exemplary drive hub for a root resurfacing attachment according to principles of the invention; and 
         FIG. 11  is a perspective view of an exemplary drive hub for a root resurfacing attachment according to principles of the invention; and 
         FIG. 12  is an inboard view of an exemplary drive hub for a root resurfacing attachment according to principles of the invention; and 
         FIG. 13  is a perspective view of an exemplary chain spacer washer for a root resurfacing attachment according to principles of the invention; and 
         FIG. 14  is a perspective view of an exemplary drive shaft adapter for a root resurfacing attachment according to principles of the invention; and 
         FIG. 15  is a perspective view of an exemplary outboard washer for a root resurfacing attachment according to principles of the invention; and 
         FIG. 16  is a perspective view of an exemplary shield for a root resurfacing attachment according to principles of the invention; and 
         FIG. 17  is a perspective view of an exemplary support arm for a shield for a root resurfacing attachment according to principles of the invention; and 
         FIG. 18  is a perspective view of an exemplary shaft clamp for a shield for a root resurfacing attachment according to principles of the invention; and 
         FIG. 19  is a perspective view of an exemplary shaft clamp and support arm assembly for a shield for a root resurfacing attachment according to principles of the invention; and 
         FIG. 20  is a perspective view of another exemplary drive hub for a root resurfacing attachment according to principles of the invention; and 
         FIG. 21  is an outboard end view of the other exemplary drive hub for a root resurfacing attachment according to principles of the invention; and 
         FIG. 22  is a perspective view of an exemplary resurfacing attachment according to principles of the invention attached to a gasoline powered edger and being used by a worker; and 
         FIG. 23  is a schematic illustrating a plurality of parallel cutting chains for a root resurfacing attachment according to principles of the invention; and 
         FIG. 24  is a view of an exemplary shield attached to a gasoline powered edger. 
     
    
    
     Those skilled in the art will appreciate that the figures are not intended to be drawn to any particular scale; nor are the figures intended to illustrate every embodiment of the invention. The invention is not limited to the exemplary embodiments depicted in the figures or the specific components, configurations, shapes, relative sizes, ornamental aspects or proportions as shown in the figures. 
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a perspective view of an exemplary assembled root resurfacing attachment according to principles of the invention is provided. Shaft  145  comprises a part of a gasoline powered landscaping edger, such as, for example, the exemplary edger shown in  FIG. 22 . An engine  710  causes a cable or drive shaft that extends through the shaft  145  to rotate. Rotation of the cable or drive shaft powers a gear box or transmission  101 , which causes a spindle  102  ( FIG. 3 ) to rotate. Rotation of the spindle  102  typically drives a rotating blade used to edge a lawn. However, in accordance with the invention, the blade is removed from the spindle  102 . A root resurfacing attachment according to principles of the invention is attached to the spindle  102 , as discussed below. 
     A root resurfacing attachment  100  according to principles of the invention comprises a plurality of parallel spaced apart chainsaw chains  107 - 113  (hereinafter “cutting chains” or “chains”) mounted on a unidirectional rotating hub  105 . The hub  105  and chains  107 - 113  are discussed in greater detail below. An end cap  120 , retaining washer  115 , bolt  117  and bushing  175  secure the hub and chain assembly to the spindle  102 . 
     A debris shield assembly comprises a shroud  130  that partially surrounds the top and side of the hub  105  and chains  107 - 113  facing the user to block debris. The shield assembly includes a flexible skirt  125  extends from the bottom of the shield assembly  130 . The skirt  125  helps prevent debris from passing beneath the shroud  130 . A plurality of attachments, such as screws, rivets, or nuts and bolts  126 - 128  secure the skirt  125  to the shroud  130 . An arm  140  attaches the shroud to the shaft  145 . 
       FIG. 2  is another perspective view of an exemplary assembled root resurfacing attachment according to principles of the invention. In  FIG. 2 , the side of the exemplary debris shield assembly that faces the user is clearly shown. Additionally, a one-piece arm  140  clamps onto shaft  145  and attaches to a collar  150  on the shroud  130 . The attachment at the collar  150  may be mechanical, such as a screw, rivet, weld, nut and bolt, or a snap-fit connection, or chemical, such as epoxy or other cement or bonding agent. The clamp at the shaft  145  comprises a forked end with a channel sized to receive the shaft  145 . The prongs of the forked end are urged together for clamping by tightening a wing bolt  155  and nut  156  ( FIG. 3 ). 
       FIG. 3  is an exploded perspective view of an exemplary root resurfacing attachment according to principles of the invention. The gearbox or transmission  101  and spindle  102  of the edger are shown. The spindle  102  is a male threaded spindle. A washer  180  or goes between the spindle and bushing  175 . The bushing  175  is a noncircular cross-section (e.g., hexagonal) sleeve with a female threaded central channel. The threads mate with the threads of the spindle  102 . The bushing  175  fits into a correspondingly shaped central channel in the inboard end of the hub  165 . A flange  160  defines the inboard end of the hub  165 . 
     A plurality of parallel endless cutting chains  107 - 113  are slid onto the hub  165  from the outboard end  170 . Each chain is separated from an adjacent chain by a spacer  161 - 172 . The inner diameter of each spacer  161 - 172  is about the outer diameter of the hub  165  so that each spacer  161 - 172  may slide onto the hub  165 . The outer diameter of each spacer  161 - 172  is less than the outer diameter of each circular chain loop  107 - 113  so that the spacers  161 - 172  do not interfere with cutting. The width of each spacer  161 - 172  is greater than the width of the horizontal cutting edge of the cutting surfaces of cutting teeth of each circular chain loop  107 - 113 . Thus, the spacers  161 - 172  prevent interference between adjacent cutting chains. 
     An end cap  120 , retaining washer  115 , bolt  117  and bushing  175  secure the hub and chain assembly to the spindle  102 . The bolt  117  extends through the central channel of the hub  165  and threads into the central channel of the bushing  175 . The retaining washer  115  and bushing  175  secure the chains  107 - 113  and spacers  161 - 172  on the hub  165 . 
     Referring now to  FIG. 4  another perspective view of an exemplary assembled root resurfacing attachment according to principles of the invention is provided. The spaced apart, parallel, equal diameter cutting chains separated by spacers are visible in this view. Referring to  FIG. 23 , the parallel cutting chains  107 - 113  may be positioned with opposed cutting surfaces  230 ,  231  being aligned but separated. 
       FIG. 5  provides a profile view of an exemplary endless chainsaw chain  107  (i.e., a cutting chain) for a root resurfacing attachment according to principles of the invention. An exemplary link  200  and a plurality of exemplary links are shown in  FIGS. 6 and 7 . Referring to  FIG. 6 , a link, particularly, a right hand cutter is shown. The cutting chain has left- and right-hand cutters so that the chain will cut evenly through the wood. The right hand cutter  200  includes a top plate  230  (i.e., a cutting surface), cutting corner  235 , heel  245 , gullet  220 , side plate  225 , depth gauge  215 , toe  240 , and rivet holes  205 ,  210 . The depth gauge  215 , also referred to as a raker, determines the depth of the cut. With reference to  FIG. 7 , mating preset tie straps  325 ,  330 ,  340 ,  345 , mate with tie straps  335 ,  350  or right or left cutters  200 ,  300 . A plurality of drive links  305 ,  308 ,  310 ,  315 ,  320  are disposed between the mated links. The tie straps hold the parts of the saw chain together. The fin  308  of each drive link fits in a groove in the hub  165  so the hub  165  can drive the chain  107 - 113 . 
     Any of various chain cutter sequences may be used, such as, but not limited to, left-hand cutter, tie strap, right-hand cutter, tie strap, left-hand cutter, tie strap, right-hand cutter, for the length of the chain. Alternatively the sequence may be left-hand cutter, two tie straps, right-hand cutter, one tie strap, left-hand cutter, two tie straps, right-hand cutter, one tie strap, and left-hand cutter, for the length of the chain. Another non-limiting example is a cutter sequence of left-hand cutter, two tie straps, right-hand cutter, two tie straps, for the length of the chain. 
       FIG. 8  is an outboard view of an exemplary drive hub  165  for a root resurfacing attachment according to principles of the invention.  FIGS. 10 and 11  provide side and perspective views of an exemplary drive hub for a root resurfacing attachment according to principles of the invention. The drive hub  165  includes a flange  160 . A central channel  415  extends through the outboard end of the hub  165  to a central aperture (i.e., bushing aperture)  420  shaped to receive the noncircular bushing  175 , as shown in the section view of  FIG. 9 . The noncircular (i.e., hexagonal) configuration of the bushing aperture is also shown in  FIG. 12 . A plurality of ribs  410  extend radially. The fin  308  of each drive link  305 ,  308 ,  310 ,  315 ,  320  fits in a groove in the hub  165  so the hub  165  can drive the chain  107 - 113 . As the fin  308  and v-groove  412  are correspondingly curved, the fin  308  mates with the v-groove  412  in one direction only. This arrangement makes the hub and chain unidirectional so that the cutting links lead with their cutting edges in the direction of rotation. This unidirectional configuration prevents mounting the chain backwards. 
     Referring now to  FIG. 13 , a perspective view of an exemplary chain spacer washer for a root resurfacing attachment according to principles of the invention is shown. The inner diameter d i  of the spacer  161  is about the outer diameter of the hub  165  so that the spacer  161  may slide onto the hub  165 . The outer diameter d o  of the spacer  161  is less than the outer diameter of each circular chain loop  107 - 113  so that the spacer  161  does not interfere with cutting. The width w of the spacer  161  is greater than the width of the horizontal cutting edge of the cutting surfaces of cutting teeth of each circular chain loop  107 - 113 . Thus, the spacer  161  prevents interference between adjacent cutting chains. 
       FIG. 14  is a perspective view of an exemplary drive shaft adapter (i.e., bushing)  175  for a root resurfacing attachment according to principles of the invention. The bushing  175  is a noncircular cross-section (e.g., hexagonal) sleeve with a female threaded central channel  178 . The threads mate with the threads of the spindle  102 . The bushing  175  fits into a correspondingly shaped central channel  420  in the flanged inboard end  160  of the hub  165  ( FIGS. 9 and 12 ). The end cap  120 , retaining washer  115  ( FIG. 15 ), bolt  117  and bushing  175  secure the hub and chain assembly to the spindle  102 . The bolt  117  extends through the central channel of the hub  165  and threads into the central channel of the bushing  175 . The retaining washer  115  and bushing  175  secure the chains  107 - 113  and spacers  161 - 172  on the hub  165 , by preventing them from sliding off the outboard end. Together, the retaining washer  115  and end cap  120  provide a removable outboard flange assembly that has an outer diameter greater than that of the hub  165 , but less than the outer diameter of the chains, and prevents removal or dislodgment of the chains and spacers retained on the hub  165 , without interfering with cutting action. 
       FIG. 16  provides a perspective view of an exemplary shield assembly  500  for a root resurfacing attachment according to principles of the invention. This shield includes a base  505  and a flexible cover  520 , which covers the downwardly curved portion of the shield assembly  500 . A pair of spaced apart mounting holes are provided. The shield  500  is shown mounted to a weed trimmer in  FIG. 24 . 
     A mounting arm assembly as shown in  FIG. 19 , is comprised of a clamp  540  ( FIG. 18 ) and a pivoting extension arm  525  ( FIG. 17 ) that attaches the shield assembly  500  to the shaft  145 , as also shown in  FIG. 24 . The clamp  540  grabs onto shaft  145 . The clamp  540  comprises opposed forked ends, each with a pair of prongs  550 ,  552  defining a channel sized to receive the shaft  145  at one end and a pair of prongs  544 ,  546  defining a channel sized to receive a tenon  536  extending from the arm  525 . A wing bolt  155  extends through holes  554 ,  556  in the shaft fork and a nut  156  allows tightening for clamping, as illustrated in ( FIG. 3 ). A screw extends through the holes  534 ,  546 ,  548  in the tenon  536  and arm fork  542 ,  544 . A nut tightens the screw in place and resists pivoting. The joint thus created, when loose, pivots about the axis defined by the screw. The arm attaches to the base  505  of the shield  500  using screws that extend through the elongated slot and the holes  510 ,  515  in the base of the shield  500 . 
       FIGS. 20 and 21  provide perspective and outboard views of another exemplary drive hub  600  for a root resurfacing attachment according to principles of the invention. The drive hub  600  includes an inboard flange  615 . A central channel  605  extends through the outboard end of the hub  600  to a central aperture (i.e., bushing aperture)  635  shaped to receive the noncircular bushing  175 , as shown in the section view of  FIG. 9 . A plurality of ribs  630  extend radially. The fin  308  of each drive link  305 ,  308 ,  310 ,  315 ,  320  fits in a groove  620  in the hub  600  so the hub  600  can drive the chain  107 - 113 . A rounded protuberance  625  has a radius of curvature that corresponds to the radius of curvature of the fin  308  of each drive link  305 ,  308 ,  310 ,  315 ,  320 . As the fin  308  and v-groove  620  and protuberance  625  are correspondingly curved, the fin  308  mates with the v-groove  620  and protuberance  625  in one direction only. This arrangement makes the hub and chain unidirectional so that the cutting links lead with their cutting edges in the direction of rotation. This unidirectional configuration prevents mounting the chain backwards. 
       FIG. 22  is a perspective view of an exemplary resurfacing attachment according to principles of the invention attached to a gasoline powered edger and being used by a worker  700 . Shaft  145  comprises a part of a gasoline powered landscaping edge. An engine  710  causes a cable or drive shaft that extends through the shaft  145  to rotate. Rotation of the cable or drive shaft powers a gear box or transmission  101 , which causes a spindle  102  ( FIG. 3 ) to rotate. Rotation of the spindle  102  typically drives a rotating blade used to edge a lawn. However, in accordance with the invention, the blade is removed from the spindle  102 . A root resurfacing attachment  100  according to principles of the invention is attached to the spindle  102 , as discussed below. 
     While an exemplary embodiment of the invention has been described, it should be apparent that modifications and variations thereto are possible, all of which fall within the true spirit and scope of the invention. With respect to the above description then, it is to be realized that the optimum relationships for the components and steps of the invention, including variations in order, form, content, function and manner of operation, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. The above description and drawings are illustrative of modifications that can be made without departing from the present invention, the scope of which is to be limited only by the following claims. Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents are intended to fall within the scope of the invention as claimed.