Abstract:
A mulching unit for a mulching apparatus includes at least one cutting assembly having a rotatable support element and at least one cutting element releasably mounted and movable or rotatable with respect to the support element. With this structure, it is possible to easily replace cutting elements without also replacing the corresponding support structure as well. In addition, the mulching unit may include a tubular assembly including inner and outer tube members connected using bracing members. A plurality of support elements of associated cutting assemblies may be fixedly attached to an outer surface of the outer tube member. This structure has improved resistance to impact with obstacles during the mulching operation that would otherwise cause misalignment.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates to an industrial mulching apparatus for use in mulching vegetation such as brush, trees, etc., or stump grinding. In particular, this invention relates to improvements to a mulching unit including a plurality of cutting assemblies that serially engage and mulch the intended vegetation in rapid fashion. 
     2. Description of Related Art 
     FIGS. 1-4C show a related art mulching apparatus  10 . The mulching apparatus  10  includes a tractor  12  supported on a set of wheels  14 . The tractor driver can sit within a protected cage  16  positioned on a frame of the mulching apparatus  10 . A hydraulic unit  18  connected to the tractor  12  provides a means by which a mulching unit  20  is positioned, e.g., laterally shifted, raised and lowered. The tractor  12  is commercially available from Barco, a manufacturer of tractors. Also, many details of the mulching apparatus  10  shown in FIG. 1 are described in U.S. Pat. No. 5,813,792 herein incorporated by reference in its entirety. 
     The tractor  12  is provided with one or more power sources, e.g., motors, sufficient to drive the tractor at a desired speed and to rotate the mulching unit  20  in the direction of arrow A. The mulching unit  20  can rotate at a speed of about 1,700 rpm, for example. The mulching unit  20  includes a plurality of cutting hammers  26  that are axially spaced along the length of the mulching unit  20 . A plurality of spacers  27  are provided between each of the cutting hammers  26 . The spacers  27  define sector shaped portions in which each of the hammers  26  pivots over a limited range. Movement within the sector shaped portion is in addition to the overall rotation of the mulching unit  20  in the direction of arrow A shown in FIG.  1 . Centrifugal force causes each of the cutting hammers  26  to pivot radially beyond the limits of each spacer  27  to thereby engage brush, trees or other vegetation. 
     FIG. 2 is an enlarged view of the mulching unit  20 . The cutting hammers  26  alternate with the spacers  27 , and the hammers  26  pivot within each sector shaped portion defined by the spacers  27 . The hammers  26  in one row are staggered with respect to the hammers  26  in adjacent rows to obtain a substantially continuous cutting profile. 
     FIG. 3 schematically shows the mulching unit  20  to include a pair of end plates  22  and a plurality of support rods  24 . Each support rod  24  includes a plurality of cutting hammers  26 . For example, each support rod  24  holds 10 to 12 cutting hammers  26 . The cutting hammers  26  are freely rotatable about the support rods  24 , and are sometimes referred to as “flail” mulchers or mowers. 
     FIG. 4A shows an enlarged view of the cutting hammer  26 . In FIG. 4A, the cutting hammer  26  includes a through hole  28  defining an inner support surface that is slidably and rotatably mounted on one of the support rods  24  shown in FIG.  3 . The through hole  28  is partly defined by a collar  30  on which a cutting clement  32  is formed. In operation, a distal end portion of the cutting element  32  wears away or erodes due to repetitive high speed impact with vegetation, the ground, etc. As such, it is necessary to replace the cutting element  32 , which also requires replacement of the collar  30  since it is formed in one piece with the cutting element  32 . Generally, this is done by disassembling one or both of the end plates  22  from the support rods  24 , as shown in FIG. 3, and then sliding the collar  30  until the cutting hammer  26  disengages with the support rod  24 . In this manner, one or more of the spent cutting hammers  26  can be replaced with new cutting hammers  26 . 
     FIG. 4B shows another example of a related art cutting hammer  26 ′ that is similar to the cutting hammer  26  shown in FIG.  4 A. The main difference is that the cutting hammer  26 ′ is double-ended and includes first and second cutting elements  32 A and  32 B. Thus, when one of the cutting elements  32 A is spent, one or both of the end plates  22  (FIG. 3) can be detached from the support rods  24 , and the cutting hammer  26 ′ can be removed from the support rod  24  and reassembled in an opposite orientation such that the fresh or unspent cutting element  32 A, rather than the spent cutting element  32 B, engages with the intended vegetation. Otherwise, the cutting hammers  26  and  26 ′ are identical in operation. 
     FIG. 4C is representative of a right side elevation view of either of the cutting hammers  26  or  26 ′. The cutting elements  32  and  32 B (as well as the cutting element  32 A) are generally flat and blade-like and are roughly equal in width to the width of the collars  30 ,  30 ′. This is disadvantageous because the flat and blade-like shape of the cutting elements  32  and  32 B results in excessive frictional contact with the intended vegetation or the ground during the mulching operation. In particular, any dirt or other debris that comes in contact with the blade member must be directed completely around each cutting element  30  or  32 ′, which causes undue strain on the motor or power source of the tractor  12 . 
     Another disadvantage with the related art structure shown in FIG. 1 is that the mulching unit can become misaligned if the mulching unit impacts various obstacles during operation. For example, the assembly of the end plates  22  and support rods  24  may not sufficiently resist deformation when impacting obstacles during the mulching operation. 
     Another related art mulching apparatus includes a rotatable drum having bullet-like cutting elements fixedly attached to the outer surface of the drum. These cutting elements are made from tungsten or carbide and are commonly used in asphalt grinding machines. However, deformation of the drum unit is problematic because it has a relatively fragile structure not well suited to resisting impact. 
     SUMMARY OF THE INVENTION 
     One aspect of the invention relates to providing a mulching apparatus including a mulching unit and/or cutting assembly with improved cutting efficiency and cost-effectiveness for labor and/or replacement parts. Another aspect of the invention relates to retrofitting mulching units of the related art with a new and improved cutting assembly that improves cutting efficiency and cost-effectiveness for labor and/or replacement parts. Another aspect of the invention concerns reducing the amount of labor required to replace spent parts. Yet another aspect of the invention relates to improving resistance to misalignment due to impact with obstacles during the mulching operation. 
     According to one preferred embodiment of the present invention, a mulching apparatus comprises a tractor and a mulching unit coupled to and receiving power from the tractor. The mulching unit includes at least one cutting assembly having a rotatable support element and at least one cutting element releasably mounted to the support element. 
     In other preferred embodiments, each support element may include a base member and a cutting element holder member integrally formed with the base member. The base member may be a collar slidable over a support rod of the mulching unit. Furthermore, the at least one cutting element may comprise two cutting elements, and the holder member may include at least two through holes, each of the at least two through holes rotatably supporting one of the two cutting elements. The at least two cutting elements may be offset from one another so that they impact the intended vegetation in stepwise fashion. 
     Preferred embodiments of the invention include several different mulching units. One version of the mulching unit may include a plurality of rows of support rods, and the cutting element on one of the support rods may be offset or staggered from the cutting element on another one of the support rods. Another version of the mulching unit includes a rotating tube assembly having an outer tube member and an inner tube member. The inner tube member is coupled to a drive shaft of the mulching unit, and the outer tube member fixedly mounts the support element of the cutting assembly on an outer surface of the outer tube member. A plurality of bracing rings axially spaced along the drive shaft may connect the inner and outer tube members. 
     The cutting element may also take on a number of different configurations according to preferred embodiments of the present invention. In one embodiment, the cutting element may include a shank having a first end having a shaped cutting tip and second end opposite the first end having a fastener. The shaped cutting tip may have many different shapes configured according to the particular cutting needs. For example, the shaped cutting tip may be tapered, symmetrical, square or triangular in cross-section. In preferred embodiments, the shaped cutting tip may be made from tungsten, carbide or another suitably hard material that is resistant to wear and abrasion. In preferred embodiments, the first and second ends of the cutting element may include first and second shaped cutting tips, which may or may not have the same shape. In this connection, the invention also contemplates the use of a quick release mechanism so that each cutting element can be quickly replaced with a new cutting element or reversed to utilize the unused end of the cutting element. Of course, regardless of what version of mulching unit is utilized, it is not necessary to remove, replace or discard the support element from the mulching unit in order to replace or reverse the orientation of the cutting element. 
     According to yet another aspect of the present invention, a mulching apparatus comprises a tractor having a power source, and a mulching unit connected to the power source. The mulching unit includes a rotating tube assembly having inner and outer tube members, the inner tube member being coupled to a drive shaft of the power source and the outer tube including at least one cutting assembly. The cutting assembly includes a support element fixedly connected to the outer tube and at least one cutting element freely supported on and removable from the support element. In preferred embodiments, the at least one cutting element comprises at least two cutting elements that are spaced apart to define a predetermined gap therebetween. This gap allows dirt and other debris to freely flow between the two cutting elements during the mulching operation, which reduces the frictional resistance from each cutting assembly applied to the power source. In addition, each of the cutting elements may be made rotatable within the support element to further reduce frictional losses. 
     These and other aspects of the invention will be described in or apparent from the following detailed description of preferred embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention will be described in conjunction with the following drawings, in which like reference numbers refer to like parts, and wherein: 
     FIG. 1 illustrates a mulching apparatus according to the related art; 
     FIG. 2 is an enlarged view of the mulching unit shown in FIG. 1; 
     FIG. 3 is a schematic view of the mulching unit shown in FIG. 1 and 2; 
     FIG. 4A shows a first embodiment of a cutting hammer according to the related art; 
     FIG. 4B shows a second embodiment of a cutting hammer according to the related art; 
     FIG. 4C shows a right side elevation view of the cutting hammer shown in FIGS. 4A or  4 B; 
     FIG. 5 shows a cutting assembly according to a preferred embodiment of the present invention; 
     FIG. 6 is a left side elevation view of the cutting assembly shown in FIG. 5; 
     FIG. 7 illustrates the support element shown in FIG. 5, without the cutting element; 
     FIG. 8 is a top elevation view of the support element shown in FIG. 7; 
     FIG. 8A illustrates an alternative preferred embodiment of a support element according to the present invention; 
     FIG. 9A illustrates a cutting element and fastener according to a preferred embodiment of the present invention; 
     FIG. 9B illustrates a cutting element and fastener according to another preferred embodiment of the present invention; 
     FIG. 9C illustrates yet another preferred embodiment of a cutting element and fastener according to the present invention; and 
     FIGS. 10-12 illustrate yet another preferred embodiment of a mulching unit according to the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIGS. 5 and 6 illustrate a cutting assembly  50  including a support element  100  and a cutting element  200 . FIGS. 7,  8  and  8 A illustrate the support element  100  without the cutting element, and FIGS. 9A-9C illustrate various embodiments of the cutting element  200 ,  200 ′,  200 ″ without the support element. 
     With reference to FIG. 5, the support element  100  includes a base member in the form of a collar  102  that defines a through hole having an inner support surface  104 . The inner support surface  104  is slidably and rotatably mounted one of a plurality of support rods  24  (shown in FIG.  3 ). Approximately 10 to 12 support elements  100  (weighing 8-10 lbs. each) are provided on each support rod  24 . The collar  102  is integrally coupled to a cutting element holder member  106 . The collar  102  and holder member  106  may be welded together, or they may be cast of molten metal in a single mold and formed as a single piece. The holder member  106  includes at least one through hole  108 . 
     As shown in FIG. 6, for example, the holder member  106  includes two through holes  108 . Each through hole  108  is intended to releasably and/or rotatably receive one of the cutting elements  200 . A gap G is formed between two cutting members  204  of the cutting elements  200 . Each cutting member  204  includes a shaped cutting tip  207 . The gap G is beneficial because it allows dirt and other debris to flow between the cutting elements  200 , as distinguished from the blade like cutting hammer  26  shown in related art FIGS. 4A-4C. It is also beneficial to allow the cutting elements  200  to rotate within the through holes  108  to further facilitate movement of the debris past and between the cutting members  204 . The cutting assembly  50  allows a 30% reduction in the amount of time required for mulching vegetation, e.g., large trees having a diameter of 24″-36″ or larger, as compared to the cutting blades  26  of the related art. 
     Each cutting element  200  includes a shaft  202  defining first and second ends. The first end of the shaft  202  includes the shaped cutting tip  207 , which is preferably made of a hard material such as tungsten and/or carbide which is resistant to abrasion and frictional contact. The shaped cutting tip  207  should also be resistant to impact as well. A second end of the shaft  200  includes a fastening element, such as a nut  206 , that is threaded onto a threaded portion  202 A of the shaft  202  (FIG.  9 A). It is not necessary to thread the entire length of the shaft  202 —a portion  202 B of the shaft  202  may remain smooth and unthreaded, as shown in FIG.  9 A. The cutting element  200  is releasably mounted to the support element and therefore can be easily replaced without requiring replacement of the support element  100  or undue labor. 
     FIG. 7 illustrates the support element  100  shown in FIG. 5, but the cutting element has been removed for clarity of illustration. FIG. 8 is a top elevation view of the support clement  100  shown in FIG. 6 with the cutting element removed. 
     FIG. 8A is an alternative preferred embodiment of a support element  100 ′ according to another preferred embodiment of the invention. In FIG. 8A, the support element  100 ′ includes first and second through holes  108 A and  108 B. The through hole  108 A is offset from the through hole  108 B such that the a cutting element positioned within the through hole  108 A contacts the vegetation slightly before the cutting element positioned within the through hole  108 B contacts the same vegetation. In this manner, energy drain to the power source of the tractor can be stepwise applied, which reduces shock to the energy source. Thus, the mulching unit  20  can run smoothly and with less interruption required to power up to the proper rpm. 
     FIG. 9A shows the cutting element  200  shown in FIGS. 5 and 6. In FIG. 9A, the nut  206  is threadably attached to the threaded portion  202 A of the shaft  202  of the cutting element  200 . In an arrangement not shown, a standard bolt can be used if the cutting member  204  is suitably threaded. To reduce the possibility of the nut  206  becoming detached from the threaded portion  202  during high speed operation, it is also possible to additionally tack weld the nut  206  onto the shaft  202 . Alternatively, the nut  206  can be replaced with a locking nut or a locking pin arrangement, so that the cutting elements  200  can be easily replaced. The cutting element  200  shown in FIG. 9A is the type commercially available for use in an asphalt grinding machine. 
     FIG. 9B shows an alternative embodiment of a cutting element  200 ′ according to the present invention. The cutting element  200 ′shown in FIG. 9B is similar to the cutting element shown in FIG. 9A, but includes a square ended shaped cutting tip  207 ′ that is particularly useful for cutting vegetation. The cutting tip could also have other polygonal or symmetrical cross sections, such as triangles, hexagons, etc. 
     FIG. 9C shows yet another embodiment of the present invention. The cutting element  200 ″ includes first and second shaped cutting tips  207 A and  207 B. The first shaped cutting tip  207 A may be similar to the shaped cutting tip  207  shown in FIG. 9A, while the second shaped cutting tip  207 B may be similar to the shaped cutting tip  207 ′ shown in FIG.  9 B. The second shaped cutting tip  207 B may include a threaded assembly (not shown) which is threaded onto the shank  202 ″, like the nut  206  or  206 ′ in FIGS. 9A and 9B, respectively, or an alternative fastening mechanism can be used, such as a quick release mechanism that facilitates removal or reversal of the cutting element  200 ″. For example, the second shaped cutting tip  207 B may include a blind bore  205  that can receive the shaft  202 ″. When a hole  206 A on the shaped cutting tip  207 BA aligns with a hole  206 B formed on the shank  202 ″, a separate pin member  209  can be inserted into both holes  206 A and  206 B, thus forming a mechanical lock. Additionally, the holes  206 A and  206 B can also coincide with another hole (not shown) formed in the holder member  106 ,  106 ′ of the support element  100 ,  100 ′. Also, although different shaped cutting tips are shown in FIG. 9C, the shaped cutting tips  207 A and  207 B may also be identical. 
     The use of the cutting elements  200 ,  200 ′ or  200 ″, especially if used in conjunction with the support element  100 ′ of FIG. 8A, can enable significant improvements in cutting speed as well as the ability to cut large trees up to 24″-36″ in diameter or larger. 
     FIGS. 10-12 show an alternative embodiment of a mulching unit  20 ′. The mulching unit  20 ′ includes a rotating tube assembly  40  including an inner tube member  42  and an outer tube member  44 . The inner tube member  42  passes through a series of bracing rings  46  connecting the inner and outer tube members  42  and  44 . The bracing rings  46  help improve the structural integrity of the mulching unit  20 ′. The relationship between the inner and outer tube members  42  and  44  and the bracing rings  46  is shown in FIG. 11, which is a cross-sectional view along section XI—XI of FIG. 10. A shaft  48  is supplied with power from a power source for the mulching unit  20 ′. A bushing  54  is interposed between the shaft  48  and at least the outermost bracing rings  46 . 
     The outer tube member  44  includes a plurality of rows of cutting assemblies  50 ′. In the example shown, each row includes about  12  cutting assemblies  50 ′. In addition, although not shown in FIG. 10, the cutting elements in one row are staggered from the cutting elements in the adjacent rows so that a substantially continuous cutting profile can be formed as the mulching unit  20 ′ is rotated. 
     Each cutting assembly  50 ′ is fixedly mounted on an outer surface of the outer tube member  44 . As such, each cutting assembly  50 ′ is not mounted on a support rod  24 , as shown in FIG.  3 . Rather, the support element  100 ′ includes a base member in the form of a substantially flat or slightly curved plate member  101  that is fixedly mounted onto the outer surface of the outer tube member  44 . The plate member  101  can be welded or otherwise bolted to the outer tube member  44 . In FIG. 12, the cutting elements are not shown for clarity, but can be similar to those shown in FIGS. 9A-9C. Although the through holes  108 ″ are shown as being uniformly spaced from the outer surface of the outer tube member  44 , they also may be offset in the manner shown in FIG.  8 A. 
     The structure shown in FIGS. 10-12 is advantageous since there is no requirement to form a collar or to assemble the collar onto the support rod  24 , as in the embodiments of FIGS. 5-8A. Also, like the earlier described embodiments, it is not necessary to remove the base member (plate member  101 ) from the mulching unit  20 ′ to replace the cutting elements. The double walled tube assembly  40  also improves resistance to warping or bending when the mulching unit  20 ′ encounters obstacles that tend to bend or otherwise warp the mulching unit  20 ′. 
     While the invention has been described in conjunction with preferred embodiments thereof, it is evident that many alternatives, modifications and variations may be apparent to those skilled in the art. For example, while the cutting assemblies according to the preferred embodiments described are shown to include two cutting elements, the present invention also contemplates cutting assemblies including a single removable cutting element. In addition, while the shafts of the cutting elements preferably include a circular cross section, which allows rotation of the cutting elements within the holder members of the support elements, the shafts may also be of a non-circular cross section that allows the cutting elements to reciprocate but not rotate. Accordingly, preferred embodiments of the invention as set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the preferred illustrated embodiments.