Abstract:
A wood fragmenting rotor assembly has a drive shaft driving a series of radially projecting hammers. Replaceable fragmenting knives are removably secured to the leading portions of said hammers and have generally axially extending fragmenting edges. An impaling tool having a generally conical leading end is carried on the hammers radially inwardly of the edges to project a generally tangentially predetermined distance forwardly and provide an initial rigid work contacting portion ahead of and cooperating with the knife edges.

Description:
The present application claims the priority of U.S. provisional application, Serial No. 60/159,174 filed Oct. 13, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to machinery for reducing waste wood, such as demolition debris, pallets, ties, large timbers, old lumber, stumps, brush, dead trees, and the like to particulates which are useful, for example, as mulch ground cover. 
     The machines widely used today for reducing such waste wood and like waste products are the tub grinder with its hammer mill underlying the floor opening in the tub, and the so-called force feed horizontal machines frequently referenced as “wood hogs” in which a swingably mounted feed roll cooperates with an underlying chain conveyor to feed waste wood to a rotary drum having reducing comminuters or hammers on its periphery. 
     In the past, hammer blocks, having forwardly projecting, spaced apart radially inner and outer elongate, carbide coated tooth edges have been used to fragment waste wood. The blocks can be rotated 180° to reposition the less rapidly wearing radially inner edge as the outer tooth edge, after the appearance of a certain amount of wear on the original outer edge. Such hammer blocks require quite frequent replacement, with the machines expensively in a “down” condition while the replacement is taking place. Moreover, the fragments produced by such toothed hammer blocks are of a somewhat bulky character. Also, on the market are conical tooth comminuting members mounted on support members which have no tooth edges. While such conical tooth members operate well to fragment wood products, they also tend to produce a relatively coarse or bulky product. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a new concept involving marrying the conical tooth to a hammer knife block having at least one forwardly protruding axially extending tooth edge which cooperates with the conical tooth to produce a better product for use as a mulching agent. The hammer assembly of the invention produces more completely shredded, thinner, feathery looking fragments in a consistent manner. The conical or generally bullet-shaped projecting tooth of the new assembly first engages the wood piece to tend to impale it, and then tear it, and the torn piece is then immediately reduced further by the tooth edge or edges which follow closely behind the conical tooth. The forwardly projecting conical tooth further protects the hammer assembly in the sense that the edge or edges of the tooth or teeth wear less rapidly then previously. Moreover the conical tooth or teeth involved in the invention may incorporate a bolt-like member which secures the knife assembly in position on its hammer shoe. 
     One of the prime objects of the invention is to provide a hammer assembly which will operate to shred a more desirable mulching product in a very efficient and rapid manner. 
     Another object of the invention is to provide a hammer assembly having an extended effective service life, and which, when required, can be readily and rapidly adjusted or replaced. 
     A further object of the invention is to provide a hammer assembly which operates extremely effectively in tub grinders and wood hogs, particularly, and greatly improves the overall operation of these machines. 
     Other objects and advantages of the invention will become apparent with reference to the accompanying drawings and the accompanying descriptive matter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The presently preferred embodiment of the invention is disclosed in the following description and in the accompanying drawings, wherein: 
     FIG. 1 is a somewhat schematic side elevational view of a tub grinder, which utilizes the invention; 
     FIG. 2 is a schematic side elevational view of the rotor assembly which is used in the hammer mill employed in the tub grinder; 
     FIG. 3 is an end elevational view thereof; 
     FIG. 4 is a greatly enlarged, schematic side elevational view of the new hammer assembly; 
     FIG. 5 is a greatly enlarged, side elevational view of the conical tool used in the hammer assembly; 
     FIG. 6 is an end elevational view thereof; 
     FIG. 7 is a side elevational view of a typical wood hog machine; 
     FIG. 8 is a greatly enlarged side elevational view of the drum assembly used on the wood hog; 
     FIG. 9 is an end elevational view thereof; 
     FIG. 10 is a greatly enlarged side elevational view of the hammer assembly of the invention; as used on the wood hog; and 
     FIG. 11 is an end elevational view thereof. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now more particularly in the first instance to FIGS. 1-6, in the first instance, the tub grinder, generally indicated at TG, includes a mobile chassis frame  10 , mounted on wheels  11  which have axles  12  supporting the frame  10  via a suitable suspension system (not shown). The tub grinder depicted is of the type disclosed in the present assignee&#39;s U.S. Pat. No. 5,419,502, which is incorporated herein by reference. 
     The tub  18  is annular in configuration and includes a rotatably mounted side wall  19 , and a bottom wall  20 , which is fixed to the frame  10 . The wall  20  includes a generally radially extending opening or slot, as usual, and below the slot is the comminuting hammer mill assembly, generally designated  23 , which is mounted on the frame  10 . 
     Support framing  24  mounts the hammer mill assembly on the frame and bearings  25  are provided for journaling the shaft  26  of the comminuting rotor assembly shown more particularly in FIG.  2 . The shaft  26  is coupled as at  27  to a shaft  28  driven by the diesel engine DE, which drives the otherwise fixed shaft  26  in rotation. Fixed on the shaft  26  between fixed end plate members  26   a  as shown in FIG. 2, is a helical array of side-by-side circumferentially staggered rotors R. Surrounding the lower portion of the hammer mill rotor assembly, is the usual screen grate  29 , through which particles are delivered to a conveyor  46 - 46   a  and on to a discharge conveyor  47 . 
     Affixed to rotor members or discs R, as with bolts  48  extending through bolt openings  49 , as shown in FIG. 4, is the support or shoe  50  which supports the hammer assembly. Each of the shoes  50  has a generally radially extending and projecting integral head or hammer portion  51  provided with a flat front face  52 . Each of the shoe heads  51 , also, is provided with a pair of through openings  53  and  54 . It is on the front face  52 , in terms of the direction of rotation of the rotors R, that a hammer knife block or plate  55  is received and it will be seen that the plate  55  portrayed has openings  56  and  56   a , which align with the openings  53  and  54 . 
     Hammer knife plate  55  is provided with radially inner and outer tooth or knife edges  57  and  58  on forwardly projecting teeth  57   a  and  58   a . While the double edge construction is greatly preferred, some knife constructions could utilize only radially outer edges  57 . As FIGS. 2 and 4 indicate, the cutter edges  57  and  58  are coated with a hard, more wear resistant material than the steel of plate  55  along their edges as at  57   b  and  58   b , and along their forwardly facing side edges as at  59 . Also carbide, or otherwise, coated are the radially inner and outer edge relief surfaces  57   c  and  58   c . The coating material can be welded or brazed to the surfaces in the well known manner. The plate  55  has radially inner and outer openings, each generally designated O, with rear portions  60  and  61  aligning respectively with the openings  56  and  56   a , and with enlarged front portions  62  and  63  bolt-head-configured to receive bolt hex heads. 
     As previously, a bolt member B may extend through the openings  61 ,  57 , and  54 , with the bolt head  65  snugly received in the opening  63 . Nuts  66  may then be employed to clamp the blocks or plates  55  to the shoe head portions  51 . 
     Provided to extend through the openings  62 ,  56 , and  53  is the shank portion  68  of a special impaling or work piercing tool member, generally designated T, which is particularly well shown in FIGS. 5 and 6. The tool member T includes a bullet-shaped frontal portion, generally designated BT, fronted by a preferably carbide conical tip  70 , which is indented relative to a preferably carbide frustoconical portion  69 , as shown at  71 . Rearwardly of the portion  69  is a cylindrical portion  69   a , connecting with a hex head  72 , which matches and snugly fits into the opening  62  provided in the member  55 . As FIG. 4 shows, the cylindrical portion  69   a  joins to the conical or frustoconical portion  69  at  69   b.    
     In the embodiment disclosed in FIG. 4, it is the conical portion  69 , carrying the tip  70 , which projects forwardly of the edges  57  and  58 , and this general orientation provides a very rigid construction. The special tool T performs a dual function in the sense that it also functions to assist the bolt B in securing the member  55  in position, the shank  68  of the tool T being threaded as at  73  so that the clamping can be accomplished using a nut  74 . 
     FIG. 7 shows a typical horizontal wood processing machine or wood hog, which is shown mounted on a trailer frame F, which may be readily towed to the site of use. The machine frame F is supported by rear wheels  75  and by suitable, vertically adjustable columns at the front end of the machine. Side walls  76  define a top open bin on the floor of which a wood receiving conveyor system, generally designated CS, is provided. The conveyor CS includes motor driven, longitudinally extending endless chains  77  traveling around suitable sprockets  78 , and a driven material feed wheel, generally designated  79 , rotatably mounted on a frame  80  which is pivoted at  81  for vertical movement, operates with the conveyor CS to constitute a feed works for feeding material to be comminuted to a comminuting drum, generally designated  82 . Drum  82  travels in a direction of rotation with respect to an anvil A indicated by the arrow in FIG.  7 . Provided beneath the drum  82  is a grate  83  which delivers properly fragmented chips to an underneath conveyor  84 , leading rearwardly to a discharge conveyor section  85 . 
     FIGS. 8 and 9 show the comminuting drum  82  fixed on a shaft  86  and it will be seen that the hammer assemblies of the present invention are fixed on the periphery of the drum  82 . As FIGS. 10 and 11 illustrate, fixed in openings  82   a  on the drum surface  82  are generally radially projecting heads, or hammers, or supports  87 , corresponding to the shoe or hammer heads  51 . 
     The hammer assembly is virtually identical to the hammer assembly previously described and its component parts are similarly identified with the same numerals as used previously. In FIG. 10, it will be noted that the rear end of radial support  87  is recessed as at  87   a  to better shield nuts  74 . In this version, block  58  is provided forwardly of recess  87   a  with a series of spaced inversely U-shaped carbide beads  89 , which extend along the top wall of the member  87  and down the sides thereof. 
     In operation, the wood product is first initially contacted by the leading ends  70  of the tool T and then impaled on the portions  69 , which tend to rip or tear the material. This torn material is then immediately engaged by the carbide coated tooth edges  57 , or  57  and  58 , which further assist the fragmenting or comminuting action of the hammer assembly. This occurs in many instances while the front ends of the tools T, in effect, hold the work to greatly assist the fragmenting action. After initial fragmenting impact, the fragments are subjected to shearing action at the anvil A in FIG.  7  and finally to the reducing action of the grate as illustrated in the present assignees U.S. Pat. No. 5,713,525, also incorporated herein by reference. 
     While generally speaking, conical type tools have been used previously, as have the toothed members  55 , the conical type tools T, as illustrated particularly in FIGS. 4-6 and  7 - 10 , to our knowledge, have not been used in conjunction with a block having a tooth edge  57  or tooth edges  57  and  58 . Here the tooth edges  57  and  58  are greatly protected by the conical tool head BT, which projects forwardly of the edges  57  and  58  and first impacts the material. With the edges  57  and  58  almost immediately thereafter contacting the material, an improved fragmenting action is achieved by the composite hammer assembly. 
     Hammer assemblies already in the field can be refitted with the tool members T by simply removing the bolt B which is used in the radially outer opening, and replacing it with the special tool T. In some instances, it may be desirable to use two tool members T in place of the two bolts B presently used in the field in openings  56  and  56   a.    
     The disclosed embodiment is representative of a presently preferred form of the invention, but is intended to be illustrative rather than definitive thereof. The invention is defined in the claims.