Abstract:
A comminuting apparatus includes a frame, a set of overlapping scissor rolls, a first drive motor, and a second drive motor. The frame has an enclosure with an entrance opening for receiving waste material. The set of overlapping scissor rolls is carried within the enclosure for rotation, including a first scissor roll and a second scissor roll. The first drive motor is coupled to the first scissor roll, and the second drive motor is coupled to the second scissor roll. The first drive motor is operative to drive the first scissor roll at a substantially variable operating speed. The second drive motor is operative to drive the second scissor roll in co-rotation at a substantially constant operating speed.

Description:
TECHNICAL FIELD 
     This invention relates to apparatus for comminuting solid waste materials such as plastic sheet material. 
     BACKGROUND OF THE INVENTION 
     The manufacture and forming of many products from plastic produces significant amounts of plastic waste material. Applicant has previously invented several unique apparatus for comminuting severable waste material, particularly plastic sheet material, into small, rather uniform particles or pieces that can be readily recycled or disposed of in an environmentally acceptable manner. Several generations of product line have been sold by Irwin Research &amp; Development, Inc., under the product name “Chesaw” and have gained commercial success. One such prior invention is the subject of the Irwin, et al, U.S. Pat. No. 4,687,144 granted Aug. 18, 1987. Other such prior inventions are the subject of U.S. Pat. Nos. 5,836,527; 5,860,607; and 5,893,523. 
     The first prior invention of U.S. Pat. No. 4,687,144 was a vast improvement over various types of hammermills that had previously been used. The hammermills were quite bulky, extremely noisy, and prone to substantial damage when the mill received foreign material that it could not comminute. Although such prior Irwin, et al, invention was a vast improvement and was commercially successful, particularly in view of hammermills, it was rather expensive to manufacture and sometimes noisy in operation when processing certain materials. Furthermore, it was unable to satisfactorily comminute rather high density plastic materials. 
     The remaining prior inventions identified above were directed to improvements over the invention of U.S. Pat. No. 4,687,144. Such improvements were directed to improving the amount of comminuted material that could be generated in a given amount of time, to improve the manner in which the comminuting apparatus operated, and/or to enhance the ability of the comminuting apparatus to efficiently subdivide pieces of material that are otherwise difficult to comminute. 
     As an example, U.S. Pat. No. 5,836,527 was an improvement over the invention of U.S. Pat. No. 4,687,144. More particularly, an improved comminuting apparatus is provided which can significantly increase the amount of comminuted material produced in a given amount of time. Such device is relatively less expensive to manufacture, and is quieter to operate. Such apparatus provides an ability to comminute a wider variety of solid waste materials. More particularly, the solid waste comminuting apparatus carries material that is severed in the device via an airstream through a fan. Subdivided pieces of material are directed via the fan to a separator screen which is mounted within a centrifugal housing. The airstream carries small pieces through the separator screen into an outer volute chamber for discharge from the apparatus. Large pieces which are not capable of passing through the separator screen are recycled through a recycle outlet and a recycle conduit back to scissor rolls of the device for further size reduction. However, the complexity of the apparatus and the number of parts needed to construct the apparatus increased over the device of U.S. Pat. No. 4,687,144, which has proven undesirable for certain applications. 
     As another example, U.S. Pat. No. 5,860,607 is directed to an apparatus for comminuting waste materials, and includes a feed roll for feeding a continuous sheet of waste material into a shear intake manifold at a desired line speed and directing the waste material to scissor rolls. An additional feature includes a screw conveyor for recirculating subdivided pieces of comminuted material. More particularly, a feed roll delivers solid waste material into overlapping scissor rolls at a desired line speed. A pneumatic conveyor, in the form of an Archimedes screw, delivers the subdivided pieces of comminuted material for sorting and reprocessing. However, this improvement also increased the complexity of the comminuting apparatus, requiring a feed roll and a screw conveyor in addition to a pair of scissor rolls. 
     As yet another example, U.S. Pat. No. 5,893,523 is directed to an apparatus for comminuting waste material having feed roll delivery features. A feed roll is rotatably carried by a frame for directing waste material to a set of overlapping scissor rolls which shear waste material into subdivided pieces as the material passes between the scissor rolls. A separator screen is carried by the frame in association with at least one of the scissor rolls for separating subdivided pieces having a size less than a predetermined size, and for recirculating subdivided pieces having a size greater than a predetermined size. However, a separate feed roll is needed in addition to a pair of scissor rolls. 
     The present invention provides a vastly improved comminuting apparatus that is not only able to process significantly greater amounts of material in a given time, it is also better able to recirculate and sort severed solid waste material utilizing an apparatus that is formed with a simplified construction having fewer moving parts, proving more reliable, less costly to manufacture, and maintain and repair, and is more efficient to operate. It is also better able to sever a wider variety of different types of materials over a broader range of line speeds, in a feed-controlled manner from a web of material being received from a processing machine. Accordingly, the present invention provides an apparatus that is able to feed solid waste material into the comminuting is apparatus in a relatively efficient and cost-effective manner, while also being able to handle a wide variety of severable materials. 
     The present invention provides a vastly improved comminuting apparatus that is also better able to recirculate and sort severed solid waste material in the separator screen particularly in an apparatus having a simplified construction with fewer parts, which is less costly to manufacture, maintain and repair, and is more reliable. It is also better able to sever the material at a desired speed, or line speed, in a feed-controlled manner from a web of material being received from a processing machine. Accordingly, the present invention provides an apparatus that is able to feed solid waste material into the comminuting apparatus in a feed-controlled manner. 
     SUMMARY OF THE INVENTION 
     A self-feeding comminuting apparatus is provided having improved drive motor and recirculation features. According to one improvement, a pair of overlapping scissor rolls cooperate to feed waste material beneath and between the pair of scissor rolls to a recycle manifold section. The recycle manifold section delivers subdivided pieces to one of the scissor rolls to recycle the subdivided pieces for sorting and/or recirculation between the pair of scissor rolls for further subdividing. According to another feature, a set of overlapping scissor rolls includes a first scissor roll driven by a first drive motor at a substantially variable operating speed, and a second scissor roll driven by a second drive motor at a substantially constant operating speed. According to one aspect of the invention, an apparatus is provided for comminuting solid waste material. The apparatus includes a frame, a set of overlapping scissor rolls, a separator screen and a recycle manifold section. The frame has an enclosure with an entrance for receiving solid waste material. The set of overlapping scissor rolls is rotatably mounted within the enclosure for shearing the waste material into subdivided pieces when the material passes between the scissor rolls. Each scissor roll has a substantially horizontal axis of rotation, with a first scissor roll elevated relative to a second adjacent scissor roll. The separator screen is carried by the frame beneath at least one of the scissor rolls. The separator screen has a plurality of apertures for separating pieces having a size less than a predetermined size which pass through a shear outtake manifold for separation while preventing large subdivided pieces having a size greater than the predetermined size from passing therethrough. The recycle manifold section is provided within the enclosure downstream and above the scissor rolls. The subdivided pieces are passed through the set of scissor rolls and delivered to the recycle manifold section downstream and above the scissor rolls. The subdivided pieces are collected within the recycle manifold section and arc delivered via a recycle flow path to one of the scissor rolls for further delivering and shearing of the subdivided pieces between the set of scissor rolls. According to another aspect of the invention, an apparatus is provided for comminuting severable waste material into pieces. The apparatus includes a frame, a pair of overlapping scissor rolls, a screen, and a recycle manifold. The frame has an enclosure with an entrance opening for receiving the waste material. The pair of overlapping scissor rolls are rotatably carried by the frame. The scissor rolls are configured with substantially horizontal and parallel rotational axes with a first scissor roll communicating with the entrance opening and operative to feed the waste material between the first scissor roll and upward between the pair of scissor rolls. The first and second scissor rolls are operative to shear the waste material into smaller pieces as the material is passed between the scissor rolls from below. The screen is carried by the frame beneath the scissor rolls, and is configured to permit undersized smaller pieces of a size less than the predetermined size to pass therethrough and to prevent oversized smaller pieces of a size greater than the predetermined size from passing therethrough. The oversized smaller pieces are sheared into further subdivided pieces by passing upward between the scissor rolls. The recycle manifold is provided downstream and above the scissor rolls. The recycle manifold communicates with the second scissor roll. The recycle manifold is configured to receive the subdivided pieces passed between the scissor rolls, at least some of the subdivided pieces being delivered to the second scissor roll where they are again directed between the scissor rolls. 
     According to yet another aspect of the invention, a comminuting apparatus is provided having a frame, a set of overlapping scissor rolls, a first drive motor and a second drive motor. The frame has an enclosure with an entrance opening for receiving waste material. The set of overlapping scissor rolls is carried within the enclosure for rotation. The set of overlapping scissor rolls includes a first scissor roll and a second scissor roll. The first drive motor is coupled to the first scissor roll, and the second drive motor is coupled to the second scissor roll. The first drive motor is operative to drive the first scissor roll at a substantially variable operating speed. The second drive motor is operative to drive the second scissor roll in co-rotation at a substantially constant operating speed. 
     One advantage of the invention is provided in a simplified construction having a feedback control system for regulating delivery of material in t o the comminuting apparatus, and having enhanced recirculation features for recirculating material being comminuted therein. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the invention are described below with reference to the accompanying drawings, which are briefly described below. 
     FIG. 1 is a plan view of a preferred embodiment of the apparatus illustrating the top exterior of the apparatus with one waste material entrance having a portion broken away to show the scissor rolls and screen; 
     FIG. 2 is a front view of the apparatus illustrated in FIG. 1; 
     FIG. 3 is a right side view of the apparatus illustrated in FIGS. 1 and 2; 
     FIG. 4 is a left side view of the apparatus illustrated in FIGS. 1 and 2; 
     FIG. 5 is an enlarged transverse vertical cross-sectional and partial view taken along line  5 — 5  in FIG. 1 illustrating the interior of the apparatus; 
     FIG. 6 is a series of illustration views of the waste material and the reduction of the waste material into smaller and smaller particles of the material as it is progressively processed and reduced to a desired particulate size; 
     FIG. 7 is a product flow illustrated diagram showing the flow path of the waste material through the apparatus as the material is being progressively processed and reduced to the desired particulate size; 
     FIG. 8 is an isolated vertical cross-sectional view taken along line  8 — 8  in FIG. 10 of a set of scissor roll rings and feed gears on a servo feed roll illustrating the initial entrance and feeding of a piece of waste material between the scissor rolls; 
     FIG. 9 is an isolated vertical cross-sectional view similar to FIG. 8 taken along line  9 — 9 , in FIG. 10, except showing the scissor roll rings incrementally rotated to feed and sever the piece of waste material; and 
     FIG. 10 is a cross-sectional view taken along line  10 — 10  in FIG. 5 but with the screen removed. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8). 
     A preferred embodiment of the invention is illustrated in the accompanying drawings particularly showing a waste comminuting apparatus generally designated with the numeral  10  in FIGS. 1-5 for receiving solid waste material  12  and for reducing the solid waste material progressively into smaller and smaller sizes until the desired small particulate or piece size is obtained as illustrated in FIG.  6 . 
     It should be noted that the apparatus  10  is very compact even though the material is progressively reduced in size in several stages to a desired predetermined small size. The predetermined small piece size will generally depend upon the desires of the customer, the end use, and the particular material being comminuted. The solid waste material  12 , illustrated in FIG. 6, is progressively reduced to subdivided pieces  14   a  through  14   e . When the subdivided pieces are generally reduced to the is desired small size,  14   e , they are removed from the apparatus as the final product. Those subdivided pieces that have not been sufficiently reduced to the desired small size are reprocessed or recycled until they are sufficiently reduced to the desired size. 
     The apparatus  10  has a general frame  16  that may be self-supported or affixed to other apparatus, such as the discharge of a thermal-forming, or thermoforming, machine, for receiving the solid waste material  12  directly from a thermoforming machine and reducing the material for re-use. Frame  16  generally includes a general enclosure  18  that includes a front wall  20 , side walls  22  and  24 , a back wall  26 , a bottom wall  28 , and a top wall  30 . Top wall has a material receiving duct  32  having a material entrance  62  (see FIGS.  1 - 4 ), through which the solid waste material is fed into apparatus  10 . General frame  16  may be supported on legs  36  that each have individual pairs of wheels  38  at each end. General frame  16  preferably includes walls  20 - 30 , upper frame members  40 ,  42 ,  44  and  48  and cross-member  46  that are variously illustrated in FIGS. 1-5. 
     Within the enclosure  18 , two scissor rolls  50  and  52  are mounted in an intermeshing relationship for rotation in opposite directions, or corotation, in coordination with each other to receive the solid waste material  12  after being delivered via scissor roll  50 . Scissor roll  50  provides a feed roll, delivering sheet material  12  in a speed controlled manner between scissor rolls  50  and  52  to shear the solid material as the material passes between scissor rolls  50  and  52  (see FIG.  5 ). Scissor rolls  50  and  52  are each supported at each end by a bearing similar to bearing  157  of FIG.  10 . Scissor rolls  50  and  52  are positioned within enclosure  18  between an intake manifold  122  that receives the material through entrance  62 . The material, after passing through the scissor rolls  50  and  52  from beneath, ascends into a recycle manifold  124  (see FIG. 5) that communicates with a recirculation cavity  125  via recycle flow path  126 . 
     Scissor roll  50  is mounted on a shaft  64  that rotates about axis  81  (see FIG.  5 ). Scissor roll  52  is mounted on a shaft  66  that rotates about axis  83 . Axes  81  and  83  are substantially parallel with each other, both extending horizontally, and extending between the side walls  22  and  24 . However, scissor roll  50  is elevated relative to scissor roll  52  such that axis  81  and axis  83  lie in a common plane that is inclined relative to a horizontal plane. According to one construction, the resulting inclined plane lies at an angle θ (see FIG. 7) from about 15 to about 45 degrees. Axes  81  and  83  are positioned so that scissor rolls  50  and  52  have sufficient overlap to shear the material between the scissor rolls as the material passes between the rolls. 
     As shown in FIG. 7, comminuting apparatus  10  provides a system for comminuting material  12  utilizing feedback signals from sensor  98  to controllably regulate rotational velocity of scissor roll  50 . Sensor  98  detects a material condition to enable the operation of apparatus  10  substantially at a feed velocity of material  12  corresponding, for example, with a line speed of material  12  being received from a thermoforming machine. Inclination angle θ is provided between scissor rolls  50  and  52  which enables a more compact construction of recycle housing  33  because material is comminuted between rolls  50  and  52  and spills over cross-member  40  via recycle flow path  126  in a much more compact and efficient manner. It has been found that utilization of a horizontal arrangement of scissor rolls and a vertically arrayed recycle manifold section tends to cause stacking or piling of comminuted material elevationally above the pair of scissor rolls, and is not conducive to generating recirculation of comminuted material over recycle flow path  126 . Accordingly, clogging and stacking can reduce efficiency, and can mandate that housing  33  be configured elevationally higher to accommodate such stacking. Accordingly, the bias angle θ between scissor rolls  50  and  52  allows for a more compact housing  35 , and enhances recycling the comminuted material via recycling flow path  126 . 
     As shown in FIG. 5, shafts  64  and  66  are supported for rotation at each end by respective bearings  157  (see FIG.  10 ). Each of shafts  64  and  66  has hexagonal cross-sectional profiles, providing angular drive surfaces  158  (see FIGS.  8  and  9 ). 
     Each of scissor rolls  50  and  52  includes a plurality of scissor rings  160  in which each of the rings  160  has an outer circular peripheral surface  162  and an inner hexagonal bearing surface  164  that is complementary to the profile of shafts  64  and  66  so that the scissor rings  160  rotate in response to the rotation of shafts  64  and  66  (see FIGS.  8  and  9 ). Each of the scissor rings  160  includes side surfaces that form shearing edges  168  with the outer peripheral surface  162  (see FIG.  10 ). 
     In the preferred embodiment, each of scissor rings  160  has evenly angularly spaced finger knives  170  formed integrally on the scissor rings  160  and projecting radially outward of the surface  162  and forward in the direction of rotation for gripping, puncturing and transversely cutting the solid material  12 , as illustrated in FIGS. 8 and 9. Each of the finger knives  170  includes a projecting body  171  that projects radially outward from the peripheral surface  162  and projects forward in the direction of rotation. Each of the finger knives  170  includes a side shearing surface  172  and an undercut surface  174 , forming a sharp knife point  176 . The scissor ring finger knives  170  are intended to grip, puncture and transverse the cuttage piece as it is being sheared between rings  160 . 
     Each of the scissor rolls  50  and  52  further include a plurality of ring spacers  180 . Each spacer  180  has a circular outer peripheral surface  182  and an inner hexagonal surface  184  (see FIGS.  8  and  9 ). Circular outer peripheral surface  182  of each spacer  180  has a groove sized to receive the corresponding stripper finger  58  and  59  of one of frame members  42  and  40 , respectively (see FIG.  5 ). The corresponding circumferential groove is not indicated with a reference numeral due to its relatively thin profile in order to facilitate simplification of the drawings. The corresponding groove is sized such that fingers  58  and  59  are smoothly and cleanly received therein, preventing fingers  58  and  59  from scraping the sides of each adjacent scissor ring  160 . 
     Accordingly, each of the ring spacers  180  has a width that is slightly greater than the width of the spacer rings  160 . Each of the spacer rings  160  and rine spacers  180  are alternately positioned on shafts  64  and  66  so that a scissor ring  170  on one scissor roll opposes a corresponding ring spacer  180  on the other scissor roll, creatings a circular inter-roll cavity  186  (see FIG. 10) between the adjacent rings and outward of the intermediate rings spacers  180 . Once the material  12  is cut and sheared, it is received in the inter-roll cavity  186  (see FIG. 10) and passes between scissor rolls  50  and  52  into the recycling manifold  124 . 
     The axes  81  and  83  of the scissor rolls are sufficiently spaced so that there is a slight overlap of approximately one-eighth inch (⅛″) in the profile of the scissor rings so that as they are rotated, the material  14  is sheared by the shearing edges  168  and the finger knife  170  as a profile of the scissor ring  160  moves into the circular inter-roll cavity  186  of the opposing ring spacer  180  (see FIG.  10 ). 
     As shown in FIG. 5, once material  12  is cut and sheared by scissor rolls  50  and  52 , it is carried into recycle manifold  124 , which communicates with, and is formed in part by recycle flow path  126  and recirculation cavity  125 . Once cut and sheared material  12  collects in manifold  124  to a sufficient height, it cascades over the top portion of frame member  40 , falling into recirculation cavity  125 , where it is recycled via scissor roll  52 . More particularly, scissor roll  52  draws the material  12  between roll  52  and screen  60 , and upward between scissor rolls  50  and  52  for further comminuting. In this manner, cut and sheared material is again fed via scissor roll  52 , which serves as a feed roll, back into scissor rolls  50  and  52  by passing it between scissor roll  52  and screen  60  where individual teeth on scissor ring  160  convey and deliver sheet of material  12 , along with recirculated cut and sheared material back to roll  52  for further delivery, sorting and/or severing. 
     Material  12 , which has passed over flow path  126  and has been directed to scissor roll  52 , is thus recirculated via projecting bodies  171  (see FIG. 8) of scissor ring  160  back to scissor roll  52 , where it is reprocessed between rolls  50  and  52  for delivery back into recycling manifold  124 . Particles  14   e  of sufficiently small size are separated out via a perforated plate, or separator screen,  60 , which is provided immediately below and adjacent to rolls  50  and  52 , conforming to their general nested bottom edge configuration. Here, screen  60  has the shape of a bi-concave perforated plate. Apertures in screen  60  are sized such that sufficiently small particles  14   e  drop through screen  60  where they are collected via a collector tray, or drop pan,  84 . Tray  84  is releasably supported to frame  16  via a pair of handle release assemblies  86 . When held in place, tray  84  also holds screen  60  in place, which facilitates quick and efficient disassembly for cleaning and maintenance. 
     Collected particles  14   e , present within tray  84 , are then withdrawn through an outlet  118  (see FIGS. 5 and 7) by way of a pneumatic conveyor  72 . An air vent is provided at an opposite end of tray  84  from outlet  96  in order to ventilate outlet  96  when removing particles  14   e . Particles  14   a-d  which are not sufficiently small enough to pass through screen  60  continue to be recirculated between rolls  50  and  52  via scissor roll  52 . 
     Additionally, it has been discovered that some of the recirculated pieces  14   a-e  in recycle manifold  124  are sifted, or passed, in a reverse direction along flow path  127  where they fall backwards, or in reverse, between inner-roll cavities  186  (see FIG. 10) and return to screen  60 . In this manner, particles which have sufficiently small size  14   e  are sifted by falling back via flow path  127  to screen  60  where they are collected in tray  84 . Likewise, particles that fall back, but that are not sufficiently small in size, such as particles  14   a-d , are passed down through rolls  50  and  52  where they are reprocessed and delivered upwardly to be further recycled via manifold  124 , flow path  126  and recirculation cavity  125 . 
     As shown in FIG. 5, a plurality of feeding fingers  54  are provided adjacent scissor roll  50  in order to further facilitate the piercing and driving of material as it is fed from intake manifold  122  between scissor roll  50  and screen  60 . More particularly, each individual feeding finger  54  comprises a metal bar sized to fit in the gap provided between adjacent scissor rings  160  (see FIG.  10 ). Similarly, a plurality of metering fingers  56  are provided along scissor roll  52  to meter the delivery of recycled, or recirculated, material from recirculation cavity  125  and between scissor roll  52  and screen  60 . Each metering, finger  56  is configured to be received within the inner space cavity formed between adjacent scissor rings  160  (see FIG.  10 ). 
     As shown in FIG. 5, screen  60  is carried at each end by respective edge portions of tray  84  so as to be presented in inter-nested adjacent relation with scissor rolls  50  and  52 . Screen  60  is quickly and easily removed for maintenance, repair and/or cleaning by releasing hand release assemblies  86  such that retaining loops  104  can be releasably removed from the clasp bars  106  which facilitate the dropping of tray  84  and removal of screen  60 . Screen  60  and tray  84  are re-secured by latching loops  104  onto clasp bars  106  and securing respective hand release assemblies  86 , including pivotally latching and securing individual handles  102 . When released to a drop position, tray  84  is allowed to pivotally drop with respect to retention bars  108  which are provided at either end. A pivot is formed between retention bars  108  and tray  84  which facilitates the downward displacement of tray  84  when unlatched for cleaning and/or maintenance. Additionally, screen  60  is further secured into engagement with cross-members  46  and  48 . 
     Intake manifold  122  is configured to receive sheet material from entrance  62  of material receiving duct  32 , illustrated in FIGS. 1 and 2. New solid waste material  12  enters through one of material entrance  62  via associated material receiving duct  32  and subdivided material requiring additional recycling is recirculated via a recycling manifold section  124  where it is re-delivered by way of recycle flow path  126  to recirculation cavity  125 , or it is alternatively returned via reverse sort path  127  for sifting in screen  60  or further severing and subdividing via rolls  50  and  52 . 
     The outtake manifold  120  includes an outlet  118  (FIGS. 5 and 7) and a collection tray  84  with a pneumatic conveyor  72  facilitating the removal of the smaller-sized severed pieces  14   e  from the outtake manifold  120  and to entrain such pieces  14   e  in an airstream via an outtake pipe  114  (see FIG. 7) and pneumatic conveyor  72 . Outtake pipe  114  provides an airstream conduit for directing an airstream with entrained subdivided pieces from the shear outtake manifold  120  to an outer volute duct  135  along flow path  136  to a product outlet  112  (see FIG.  8 ). 
     The apparatus  10  includes a pair of scissor roll drive motor assemblies generally designated with the reference numerals  68  and  70  and illustrated in FIGS. 1-4. Drive motor assembly  68  comprises a variable speed drive motor assembly that includes a variable speed AC drive motor  74 , a speed reduction gearbox  76 , and a flux vector AC drive (not shown) which is housed in electrical cabinet  82  (of FIG.  3 ). Similarly, drive motor assembly  70  comprises a three-phase AC motor  78  and a speed reduction gearbox  80 . 
     More particularly, variable speed drive motor assembly  68  is configured to drive scissor roll  50  (of FIG. 5) at a regulated speed pursuant to the control system features disclosed relative to FIG. 7. A feedback signal is provided by way of material sensor  98  (of FIG. 3) which detects tension that is placed upon sheet material  12  as it is received within duct  32 . Tension is applied to sheet  12  when scissor roll  50  is operating at a speed which exceeds the speed with which such material is being admitted into duct  32 . Accordingly, the control system feature depicted with reference to FIG. 7 allows for variable speed operation of scissor roll  50  by way of variable speed drive motor assembly  68 . According to one construction, a variable speed electric drive motor sold by Sumitomo Machinery Corporation of America is utilized for motor  74 . A corresponding flux vector AC drive is also used with such motor. According to one construction, a model NTAC-2000 sensorless flux vector AC drive is utilized with motor  74 , as sold by Sumitomo Machinery Corporation of America. Such motor and drive cooperate to provide a microcontrolled variable speed drive motor assembly capable of realizing the features depicted in FIG.  7 . 
     More particularly, three-phase AC motor  78  comprises a 15 hp standard electric motor using contactors and fuses. As shown in FIGS. 2 and 4, motor  78  is coupled to drive gearbox  80  by way of a chain or belt  94  extending between a pair of associated pulleys  91  and  93  mounted to shafts  96  and  98 , respectively. Chain, or belt,  94  is contained within a pulley drive cover  92  which is supported on a bracket  90 . Motor  78  is configured to operate at a constant operating speed. However, it is understood that the dimensions of pulleys  91  and  93  can be chanced in order to configure motor  78  and gearbox  80  to operate at a different operating speed which proves suitable for use with a specific machine and/or application. For example, it may be desirable to change the substantially constant operating speed of a scissor roll  52  (of FIG. 5) when comminuting a specific type of material. Accordingly, such change in constant velocity can be made by specifically configuring the size of the pulleys for a specific machine utilization. 
     In operation, the ability to rotate scissor roll  52  at a substantially constant velocity, while regulating the variable velocity operation of scissor roll  50  enables the controlled metering of material being fed into the apparatus  10  for comminuting relative to the speed with which material is being provided to such apparatus. 
     As shown in FIG. 2, motor  74  is directly mounted onto gearbox  76  where it is supported thereon, as gearbox  76  is mounted onto frame  16  (of apparatus  10 ). Likewise, motor  78  is carried by bracket, or plate,  90  via gearbox  80 , which is likewise mounted to frame  16 . Additionally, each of gearboxes  76  and  80  are further secured to frame  16  by additional framework (not shown) such as by use of struts that are tied to the side walls  22  and  24  and frame  16 . 
     Furthermore, where belt  94  is utilized, pulleys  91  and  93  are utilized. However, where a chain is utilized, pulleys  91  and  93  are replaced by a pair of sprockets which couple together the respective motor and gearbox. 
     As shown in FIG. 7, control circuitry  128 , in the form of a microprocessor or microcontroller, receives a material status signal from material sensor  98  indicating the status of material being received within apparatus  10 . Control circuitry  128  then sends an output signal to variable velocity drive motor assembly  68  which regulates the rotational speed of scissor roll  50 . As shown in FIG. 7, control circuitry  128  also provides an input signal to constant velocity drive motor assembly  70 . According to one construction, such input signal merely comprises a signal that turns on and off the constant velocity drive motor assembly  70  so as to start and stop motion of scissor roll  52 . Accordingly, FIG. 7 illustrates a feedback control system utilizing control circuitry  128  and sensor  98  so as to vary the rate at which material  12  is fed into scissor rolls  50  and  52  based upon the detected status of material  12  entering intake manifold  122 . Where the operating speed of scissor roll  50  exceeds the delivery speed of material  12  into apparatus  10 , tension will be exerted on material  12  which causes sensor  98  to detect such condition (see FIG.  3 ). 
     As shown in FIG. 3, sensor  98  comprises an angled sheet metal plate  100  that includes an actuator arm. Such plate  100  and actuator arm are pivotally supported relative to duct  32 , and are biased towards an upwardly raised or elevated position by way of a coil spring. Application of tension on a sheet of material extending thereabout causes plate  100  to be downwardly biased so as to coact against such coil spring. As shown in FIG. 4, sensor  98  includes a microswitch which detects the rotated position of plate  100 . The detected downward rotation of plate  100  sends a signal to control circuitry  128  (of FIG. 7) which provides a feedback signal on the status of material being received within apparatus  10 . Accordingly, the operating velocity of scissor roll  50  can be adjusted so as to maximize operating efficiency for a particular detected status of material  12  being received within intake manifold  122  based upon detected sheet material tension. 
     Accordingly, scissor roll  50  can be operated as a feed roll that is rotated at a desired speed for a particular material  12  being received within apparatus  12 , as shown in FIG.  7 . Such a feedback control system ensures optimized performance of apparatus  10  under a number of operating conditions and/or when being utilized with a number of different materials  12 . For example, web  12  can comprise a web of material being received from a thermoforming press. Material  12  is drawn via scissor roll  50  substantially at a line speed by actuating variable velocity drive motor assembly  68  according to an input signal being received from material sensor  98 . Accordingly, operating speeds and efficiencies can be maximized by variably regulating the rotational speed of scissor roll  50 . 
     Apparatus  10  further includes a pneumatic conveyor  72 , as shown in FIG. 7, for conveying subdivided pieces  14  from outtake manifold  120  and directing the pieces to a product outlet  112 . Product outlet  112  ejects the pieces  14 e where the sufficiently small subdivided pieces  14   e  are collected in a storage vessel (not shown) for later recycling. 
     The pneumatic conveyor  72  includes a centrifugal fan  110  for generating an airstream of sufficient velocity and volume to remove the subdivided pieces from the shear outtake manifold  120  and to entrain the pieces  14   c  in the airstream (see FIGS.  5  and  7 ). The centrifugal fan  110 , illustrated in FIG. 7, includes a housing  130  having a central propeller section  115 , a peripheral volute section  133 , and an outer volute duct  135 . The central propeller section  115  includes a central inlet  134  with a propeller assembly  132  mounted within the central propeller section  115 . The propeller assembly  132  includes a shaft  131  with radial blades  137  extending radially outward for directing the air from the central inlet  134  radially outward and tangential into the peripheral volute section  133 . A motor  116  (see FIG. 1) is connected to the shaft  131  (see FIG. 7) for rotating the blades  137  at the desired speed to obtain an airstream having the desired velocity and volume. 
     Centrifugal fan  110  communicates with outer volute duct  135  and product outlet  112  for discharging the small particles  14   e  that have passed through the separator screen  60  via outtake pipe  114 . 
     As illustrated in FIGS. 5 and 7, the cross-frame members  40  and  42 , each comprising a stripper plate, each have notched stripping fingers  58  and  59 , respectively, formed along an edge thereof projecting between the scissor rings  160  and into the inter-roll cavities  186  along the lower profile of the scissor rolls  50  and  52  to strip any of the subdivided pieces from between the scissor rings  160  after the pieces have been severed. In one version, each finger is secured to each plate with one or more fasteners (not shown). Each finger  58 ,  59  rides in a complementary groove (not numbered) in the radial outer surface of ring spacer  80  (of FIG.  5 ). 
     During the operation of the apparatus  10 , solid waste material  12  is fed into the apparatus  10  through entrances  62  of duct  32  (see FIGS. 1,  3  and  4 ) and into the intake manifold  122  where it is directed to the scissor roll  50  (see FIGS.  5  and  7 ). Scissor roll  50  then moves the material along feeding fingers  54 , pulling the material  12  between scissor roll  50  and feeding fingers  54 . The engaged material is delivered by scissor roll  50  along screen  60 . In some cases, feeding fingers  54  can also help to sever material  12  during delivery between scissor rolls  50  and  52 . Scissor roll  50  then further engages the material, causing some of the material to rip and sever, as roll  50  is rotated. Scissor roll  50  then delivers or circulates the material along screen  60  for sorting and between rolls  50  and  52  where it is engaged and severed. 
     As the delivered material  12  engages rolls  50  and  52 , material  12  is gripped by the finger knives  170  (see FIGS. 8 and 9) and pulled between the scissor rolls  50  and  52 , with the scissor rings  160  and its shearing edges  168  shearing the solid waste material into subdivided pieces. As previously mentioned, the finger knives  170  grip the material, puncture the material and transversely cut the material even further as it passes between the rolls. The severed pieces  14   a - 14   e  (see FIG. 6) then ascend into the recycle manifold section  124 . The stripper fingers  58  and  59  strip any severed pieces from the rolls  52  and  50 , respectively, and remove them into the recycle manifold section  124 . 
     After material and subdivided pieces  14   a-e  are delivered to scissor roll  50 , scissor roll  50  in combination with scissor roll  52  further delivers the pieces along screen  60  where small subdivided pieces  14   e  are separated from the remaining material and pieces. Those subdivided pieces that are larger than the apertures or holes in the separator screen  60  are carried along rolls  50  and  52  where they are delivered between rolls  50  and  52  for further severing and subdividing, or comminuting. The further subdivided pieces are then delivered into recycle manifold section  124 . Such further subdivided pieces  14   a - 14   e  are then either redelivered via recycle flow path  126  to recirculation cavity  125  for further delivery and subdividing, or are received in a reverse direction via reverse-direction sort path  127  back along screen  60  where sufficiently small particles  14 e are separated out through screen  60  and remaining portions are further subdivided between rolls  50  and  52 . The small pieces  14   e  that pass through the separator screen  60  are directed from the apparatus through the product outlet  118  to a pneumatic conveyor  72  for delivery to final product outlet  112 . 
     The large particles or pieces  14   a - 14   e  will be continually recycled through recycle flow paths  126  or  127  until their size is reduced below that of the preselected size of the apertures of the separator screen  60 . Screen  60  can be easily replaced in order to provide apertures with a desired size for implementing a desired sort of particles. Screen  60  can be constructed from screen material or any suitable perforated sheet or plate, or other suitable construction. 
     In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.