Abstract:
A method and apparatus for reducing vehicle tires includes a feed mechanism for transferring flattened tire treads into a shearing assembly which includes a rotating shear assembly. The shear assembly is comprised of a rotating arbor supporting a stack of a plurality of cutting plates having cutting inserts extending therefrom in a variable helical pattern. The inserts rotate past an anvil edge, and the sharp edges of the inserts shear the infeeding edge of the tire tread. The inserts are replaceable, and the spacing of the cutting head and anvil edge is variable to optimize the shearing action.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the priority filing date of Provisional Application No. 60/429,961, filed Nov. 26, 2002 
     
    
     
       FEDERALLY SPONSORED RESEARCH  
         [0002]    Not applicable.  
         SEQUENCE LISTING, ETC ON CD  
         [0003]    Not applicable.  
         BACKGROUND OF THE INVENTION  
         [0004]    1. Field of the Invention  
           [0005]    The present invention relates to a system for reducing tires to small particulate material and, more particularly, to an apparatus for reducing tires using a shear technique.  
           [0006]    2. Description of Related Art  
           [0007]    Tires are typically made of rubber or rubber-like material, and when the tire tread is worn, or when the tire has sustained some damage, requiring a discarding of the tire, a serious problem arises as to proper disposal. Millions of tires are discarded annually and because of their bulk and lengthy life, even under extreme weather or burial conditions, they create an unsightly and massive eye-sore, and a need for extremely large storage areas. On some occasions, the collection of tires will catch on fire and burn for many months or even longer, further contributing to environmental concerns.  
           [0008]    Tire components (rubber, rubber-like substances, reinforcing fiber, steel wire, etc.) have been engineered to exhibit durability and longevity in extremely hostile environments, such as severe temperature changes, exposure to salt and other corrosive chemicals, continuous flexure, abrasion and ablation, UV exposure, countless cycles of wetting and drying, and the like. The very factors that have created reliable and tough tires have, ironically, mitigated against any easy method for disposing of worn or damaged tires.  
           [0009]    Many attempts have been made to solve this problem, including the use of shredders, cutters, etc., but none of these prior art devices have proven satisfactory for a number of reasons. These include the large required size of the apparatus, the power requirements, and the inability to economically and reliably produce small particulate fragments at a reasonable cost. Typical prior art apparatus generates a great amount of heat, creating the hazard of potential dust explosion and requiring cooling measures such as liquid spray heads to remove the heat and prevent fire or explosion. The introduced liquid then presents a further material handling problem for the resulting slurry.  
         BRIEF SUMMARY OF THE INVENTION  
         [0010]    The present invention generally comprises a method and apparatus for reducing worn or damaged vehicle tires for disposal or recycling of the tire materials. The invention makes use of a shear technique and preferably feeds the tread portion of the discarded tire through rollers and into an apparatus where the tire is cut into pieces of one-quarter inch, one-eighth inch, or even smaller; e.g., a powder form, through a shearing action.  
           [0011]    The tire to be reduced is first cut so that the circumference of the tire is no longer continuous. The bead portions of the tire are then cut away from the tread portion and the latter is fed between upper and lower roller assemblies, at least one of which is pressure loaded so as to exert a flattening pressure on the normally curved tread portion of the de-beaded tire. Rotation of the rollers causes the tread to move towards the shear mechanism of the present invention. Ground rubber is removed by vacuum and discharged onto a magnetic-driven drum that removes steel particles from the rubber granules or pieces. The rubber granules may then pass through a screen classifier which sizes or grades the particulate material.  
           [0012]    At the end of the feed mechanism and just before the cutting head there is a stationary anvil, which is attached to the feed mechanism. The tire is fed up to a rotating cutting head and sheared off at the point of contact between the anvil and insert cutters of the cutting head. At this point, the tire is cut, not ground down like most prior art tire shredders. Very little heat is produced in the reduction of the tire, so no cooling agent is necessary. This makes the invention cost effective and eliminates the mess and material handling problems created by the cooling agent.  
           [0013]    The cutting head is comprised of a variable number of cutting plates mounted as a stack on a rotating arbor. Each cutting plate has a variable number of insert cutters. The cutting inserts have multiple cutting edges and can be rotated and changed as needed. Each cutting insert is attached to the cutting plate by a positive mechanical pin. The cutting plate is formed to allow each cutting insert to have an individual seat which in turn houses the positive mechanical pin. The number of cutting plates and the number of insert cutters vary in accordance with the size of the tire reduction unit. The cutting plates are positioned and held on the cutting head by a keyway. By adjusting the position of the keyway on the individual cutting plates, a helix pattern defined by the insert cutters on the adjacent plates may be selectively varied to produce the optimum shearing effect. The helix pattern determines that all of the rotational force of the arbor is applied by only a few of the cutting inserts to the tire piece at any one instant, so that the cutting inserts cut through the leading edge at the anvil, rather than grinding or abrading the tire piece, whereby heat generation is minimized. Also, the impact point of the cutting inserts progresses laterally across the leading edge of the tire piece as the arbor rotates.  
           [0014]    The feed mechanism is adjustable to allow the anvil to be adjustably spaced with respect to the cutting head ( 6 ). This feature permits adjustment of the tire reduction unit to a desired tolerance between the anvil and the cutting head. The smaller the gap between the anvil and the cutting head, the smaller the rubber particles which will be produced.  
           [0015]    It will be understood that the particulate material created by this apparatus can be used for many commercial applications such as a fill material in numerous composition. Even if the particulate material is not reused, it presents a better opportunity for disposal compared to disposing of the complete, intact tire tread. (The reduced tire particulates occupy far less volume than an intact tire.) It should also be noted that tires may have steel reinforcement, and the present invention incorporates a mechanism for separating this metal from the rubber after the de-beading or shearing operation.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0016]    [0016]FIG. 1 is a perspective view of the apparatus of the invention (with housing removed) for reducing tires to particulate material.  
         [0017]    [0017]FIG. 2 is a plan view of the feed mechanism and the cutting head of the tire reducing apparatus of the invention.  
         [0018]    [0018]FIG. 3 is a perspective view of the feed mechanism, cutting head, and conveyor belt of the tire reducing apparatus of the invention.  
         [0019]    [0019]FIG. 4 is a side elevation of the feed mechanism, cutting head, anvil, and conveyor belt of the tire reducing apparatus of the invention.  
         [0020]    [0020]FIG. 5 is a partially cutaway plan view of a cutting plate of the cutting head assembly of the invention.  
         [0021]    [0021]FIG. 6 is an enlarged partial perspective view of a cutting plate of the cutting head assembly of the invention.  
         [0022]    [0022]FIG. 7 is a plan view of the cutting head assembly, showing one helical arrangement of the cutting plates.  
         [0023]    [0023]FIG. 8 is a perspective view of the cutting head assembly shown in FIG. 7.  
         [0024]    [0024]FIG. 9 is a plan view of the cutting head assembly, showing another helical arrangement of the cutting plates.  
         [0025]    [0025]FIG. 10 is a perspective view of the cutting head assembly shown in FIG. 9.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    The present invention generally comprises a method and apparatus for reducing worn or damaged tires for disposal or recycling of the tire materials. The method of the invention will be described in concert with the description of the apparatus.  
         [0027]    With regard to FIG. 1, the tire reducing apparatus includes a structural framework  11  that supports the dynamic components as well as a housing or shroud for containing the dust and particulates generated by the dynamic components. The framework  11  supports a feed mechanism  12  (only the lower half shown in FIG. 1 for clarity) that is disposed adjacent to a cutting head assembly  13 , the feed mechanism being adapted to drive tire tread pieces and the like into engagement by the cutting head assembly. The feed mechanism  12  is preferably, but not necessarily, driven by a hydraulic motor feed by a hydraulic pump. A variable speed electric motor  14  is connected through a belt or chain drive to a pulley wheel  16  which is secured to the drive shaft  17  of the cutting head assembly  13 . Thus the motor  14  may drive the cutting head at a selected rotary speed to reduce tire tread pieces transferred by the feed mechanism to the cutting head  13 . The resulting particulates are received by a chute  18  extending below the cutting head  13  and directed to a conveyor belt  19  for subsequent processing.  
         [0028]    With regard to FIGS.  2 - 4 , the feed mechanism includes upper and lower assemblies  21  and  22 , each supporting toothed wheels, the toothed wheels of the assemblies  21  and  22  being vertically separated a distance that is minimally sufficient to define a feed path through which tire tread pieces and the like may be transferred. The lower assembly  22  includes an open framework feed bed  24 , to support the tire pieces, through which the toothed wheels protrude to engage the tire pieces. The toothed wheels of the upper and lower assemblies are driven in respective counter-rotation, as shown in FIG. 4, to drive the tire pieces in the feed direction toward the cutting head assembly  13 .  
         [0029]    The cutting head assembly  13  is comprised of a plurality of cutting plates, a representative one being shown in FIGS. 5 and 6. Each cutting plate  31  comprises a circular disk  32  having a central bore  33  extending therethrough and a keyway  34  machined or otherwise formed in the ID of the bore  33 . A plurality of scallop-like projections  36  extend generally radially outwardly from the periphery of the disk  32 , each projection including a ramp portion  37  extending obliquely outwardly to a lug portion  38 . Each lug portion  38  is defined by an outer peripheral surface  39  extending generally in a circle of constant diameter centered with the bore  33 , the surface  39  forming a vertex with a mounting surface  41  that extends generally radially with respect to the bore  33 .  
         [0030]    Joined to each lug portion  38  is a cutting insert  42  which is secured to the mounting surface  41 . Each cutting insert  42  is a generally rectangular solid formed of hardened carbide or the like that flares slightly outwardly from the mounting surface  41  to define sharp outer edges. Each cutting insert is provided with a central tapered hole  45  extending therethrough. A mounting hole  43  extends normally through the mounting surface  41  and through the lug portion  38  to the surface  37 . A pin  44  having a flared head extends through the hole  45  of each cutting insert  42  and is press fit or otherwise positively secured in the mounting hole  43 . The flared head of the pin  44  is recessed from the outer surface of the cutting insert, so that the cutting edges of the insert are prominent. Note also that the cutting edges of the inserts  41  extend radially outwardly from the cutting plate farther than the outermost lug surface  39 , whereby the cutting edges of the inserts are disposed to contact the tire work piece as the cutting plate rotates about its central axis. Note also that each cutting insert has multiple cutting edges and, when the radially outermost edge becomes worn, the insert may be rotated to present a fresh, sharp cutting edge, or the entire insert may be replaced.  
         [0031]    The plurality of cutting plates  31  are arranged in a coaxial stack and assembled to an arbor  51  that extends axially from the shaft  17 , the arbor extending through the central holes  33  of the cutting plates. The arbor includes a keyway channel  52  (see FIGS. 2 and 3) extending longitudinally in the circumferential surface thereof and dimensioned to engage a key, such as a woodruff key or the like, that also engages the keyway  34  of each cutting plate  31 . Thus the cutting plates are rotationally immobilized on the arbor  51 .  
         [0032]    Additionally, the cutting plates  31  vary slightly in the angular disposition of each keyway  34  about the axis of the central holes  33  of the plates  31 . This angular variation is selected so that each cutting plate is angularly offset a predetermined, angular extent that is progressive with respect to the adjacent cutting plates, whereby the lugs  38  and their cutting inserts  42  are likewise angularly offset. As a result, the cutting inserts  42  of the cutting plates  31  that form the cutting head  13  are arranged in a predetermined pattern about the outer periphery of the cutting head  13  to define the optimum cutting pattern for the material being reduced. The factors that enter into the determination of the optimum cutting pattern may include the thickness of the tire tread, the type of fiber reinforcement (Nylon®, Aramid®, steel, or the like), and the type of rubber (density, degree of cross-linking, etc.).  
         [0033]    Thus, for comparative examples, the cutting plates  31  may be angularly offset to a lesser progressive degree to define a pattern of cutting inserts that is described as multiple helical paths extending in a shallow progressive angle about the cutting head, as shown in FIGS. 7 and 8; or in multiple helical paths extending in a more acute progressive angle about the cutting head, as shown in FIGS. 9 and 10. The former enables a relatively greater number of cutting inserts  42  to shear the leading edge of the tire material at any instant, thus reducing the force applied to each cutting insert as it makes contact with the tire material; the latter presents a relatively lesser number of cutting inserts  42  to shear the leading edge of the tire material and produces greater shearing force for each insert as it impacts the tire material.  
         [0034]    With regard to FIGS. 3 and 4, another salient feature of the invention is the provision of an anvil  61  supported by the frame  11  and disposed between the feed mechanism  12  and the cutting head  13 . The anvil  61  includes a structural member extending laterally across the feed path of the feed mechanism and having an anvil edge  62  extending parallel to the periphery of the cutting head  13  and spaced apart therefrom a small, selectively variable distance. The anvil edge  62  is formed of hardened tool steel or the like and is disposed to support the leading edge of the tire piece being processed, as it engages the cutting head  13 . The support of the anvil edge  62  is significant in enabling the cutting inserts of the plates  31  to shear through the leading edge of the infeeding tire piece in a scissor-like action and prevent abrading and grinding actions that would otherwise lead to greater heat generation.  
         [0035]    The apparatus also includes a vacuum system for uptake of dust-laden air within the housing of the apparatus, and filters or the like for suppression of dust and dirt. These components are common in the prior art and need not be shown in particular herein.  
         [0036]    It may be noted that there are several factors in the construction of the apparatus that may be selectively varied to accommodate the tire material being reduced. These factors include:  
         [0037]    1) the number cutting inserts provided on each cutting plate;  
         [0038]    2) the number of cutting plates used to define the cutting head, determining the width of the cutting head;  
         [0039]    3) the helical pattern of cutting inserts in the cutting head;  
         [0040]    4) the spacing of the cutting head from the anvil edge;  
         [0041]    5) the speed at which the motor  14  drives the cutting head  13 ;  
         [0042]    6) the rate at which the tire pieces are fed into the cutting head.  
         [0043]    The first three factors are set during the machine setup stage, whereas the latter three factors may be operator-adjusted as the machine is in use to create the optimum particle size and cutting speed in accommodation to the tire material being processed. In the embodiment shown herein, the cutting head  13  is comprised of cutting plates having a diameter of about 10 inches with 12 cutting inserts per plate, and the width of the cutting head is about 2 feet. The spacing of the anvil edge from the cutting head inserts is about 0.090-0.010 inches. (The closer the spacing, the finer is the resulting fire fragments.) The motor  14  is approximately 50 horsepower, as compared to equivalent prior art devices that employ motors up to 10 times this power. It should be noted that not only is the motor much smaller than prior art devices, but the entire apparatus is compact and efficient, so that it is capable of being installed widely at numerous tire recovery locations, rather than the enormous prior art devices that are suitable only for large centralized tire processing facilities.  
         [0044]    The method of the invention includes preparing the tire pieces by first cutting through the torus-shaped tire parallel to the axis of the torus, and thereafter cutting away the bead portions from the tread portion. The latter is then fed into the feed mechanism endwise, the upper and lower feed mechanisms flattening the tread portion as it is driven into the cutting head in a flat, endwise engagement. The resulting tire fragments and crumbs are collected on the conveyor  19  and transferred to a magnetic separator, if steel filament reinforcement is present, or to a storage bin for subsequent processing.  
         [0045]    The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and many modifications and variations are possible in light of the above teaching without deviating from the spirit and the scope of the invention. The embodiment described is selected to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as suited to the particular purpose contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.