Abstract:
A comminuting device is provided having a support structure, a set of intermeshing scissor rolls, at least two entrance openings, and a bulkhead. The support structure has an enclosure. The set of intermeshing scissor rolls are rotatably carried by the support structure. The at least two entrance openings are provided in the enclosure. The bulkhead is interposed between a first one of the entrance openings and a second one of the entrance openings. The bulkhead provides a first entrance shoot and a second entrance shoot, with the bulkhead including a mouth portion configured to transfer scrap products between the first entrance shoot and the second entrance shoot.

Description:
TECHNICAL FIELD  
       [0001]     The present invention pertains to apparatus and methods for subdividing waste materials. More particularly, the present invention relates to apparatus and methods for comminuting solid waste materials, such as plastic sheet material.  
       BACKGROUND OF THE INVENTION  
       [0002]     Automated manufacturing systems that produce plastic articles have advanced to the point that they now generate significant amounts of plastic waste material at increasing rates. Other manufacturing and recycling systems also produce significant amounts of solid waste material, including plastic waste material. Many apparatus are known for comminuting waste material, such as plastic sheet material, into small, rather uniform particles or pieces that can be readily recycled or disposed of in an environmentally acceptable manner. For example, thermoforming machines mold articles that are heat formed from a sheet or web of plastic material as a pair of mating two-piece dies or molds impart an article geometry into a heated sheet of thermoformable plastic material to achieve a desired final shape. A typical thermoforming machine includes pairs of mating male and female dies, or molds, that are brought together on opposed sides of a preheated web of plastic material, during an operating cycle. The web of plastic material, including the formed articles, is then processed in a trim press where the articles are severed and removed from the web, leaving a skeleton web that is subsequently recycled in a comminuting apparatus.  
         [0003]     U.S. Pat. No. 5,893,523 discloses one comminuting apparatus suitable for use in recycling a skeleton web of scrap material that is generated from a thermoforming machine and trim press of a thermoforming line. The comminuting apparatus includes a first material entrance and a second material entrance through which solid waste material is fed into the comminuting apparatus. The first material entrance is configured to receive a skeleton of plastic sheet material, whereas the second material entrance is configured to receive pieces of scrap and start-up formed web material that are typically hand-fed by an operator.  
         [0004]     However, it is oftentimes difficult to hand-feed scrap and start-up material into the second material entrance, particularly when the comminuting apparatus is configured beneath a horizontal trim press where there is not a significant amount of clearance room. Additionally, the simultaneous delivery of waste material into two entrances can reduce efficiency by interfering with delivery of waste material at line speed from a trim press. Furthermore, the provision of such a comminuting apparatus beneath a horizontal trim press prevents operators from reaching the comminuting apparatus because typically such a configuration is shielded from operator interaction to prevent injuries and/or death. Accordingly, improvements are needed to enhance the ability to feed start-up and scrap material into a comminuting device while it is simultaneously configured for use in comminuting a skeleton web of plastic scrap material that exits a trim press.  
       SUMMARY OF THE INVENTION  
       [0005]     A comminuting apparatus is provided with a structural divider that subdivides an interior of the comminuting apparatus. At least two separate entrance openings communicate with the subdivided interior of the comminuting device. In one case, at least three entrance openings are provided in a comminuting device with each entrance opening configured to deliver solid material into the enclosure for shredding within the machine.  
         [0006]     According to one aspect, a comminuting device is provided having a support structure, a set of intermeshing scissor rolls, at least two entrance openings, and a bulkhead. The support structure has an enclosure. The set of intermeshing scissor rolls are rotatably carried by the support structure. The at least two entrance openings are provided in the enclosure. The bulkhead is interposed between a first one of the entrance openings and a second one of the entrance openings. The bulkhead provides a first entrance shoot and a second entrance shoot, with the bulkhead including a mouth portion configured to transfer scrap products between the first entrance shoot and the second entrance shoot.  
         [0007]     According to another aspect, a plastic shredding machine includes a frame, at least two intermeshing scissor rolls, and at least three entrance openings. The frame has an enclosure. The at least two intermeshing scissor rolls are rotatably carried by the frame. The at least three entrance openings are provided in the enclosure. Each of the three entrance openings is configured to deliver plastic into the enclosure for shredding between the scissor rolls. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     Preferred embodiments of the invention are described below with reference to the following accompanying drawings.  
         [0009]      FIG. 1  is a vertical side view of a thermoforming trim system of a thermoforming line including a canopy, a trim press, a packaging table, and a comminuting apparatus, with the comminuting apparatus taken in partial vertical sectional view in accordance with one embodiment of the present invention.  
         [0010]      FIG. 2  is a front view of the comminuting apparatus illustrated in  FIG. 1  taken from the right.  
         [0011]      FIG. 3  is a right side view of the apparatus as depicted in  FIG. 2  and further shown in  FIG. 1 .  
         [0012]      FIG. 4  is a left side view of the apparatus illustrated in  FIGS. 1-3 , but omitting the pneumatic conveyor and centrifugal fan assembly in order to facilitate viewing of the gear case configuration.  
         [0013]      FIG. 5  is a plan view of the comminuting apparatus of  FIGS. 1-4  with a top portion broken away to show scissor rolls and a feed roll, and further depicting provision of multiple entrance openings.  
         [0014]      FIG. 6  is a further enlarged transverse vertical cross-sectional view taken along line  6 - 6  of  FIG. 2  and illustrating the interior of the comminuting apparatus.  
         [0015]      FIG. 7  is an enlarged partial isometric view taken from above and to the right of the view depicted in  FIG. 4  to illustrate orientation and configuration of three individual entrance chutes for the comminuting apparatus. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]     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).  
         [0017]     Reference will now be made to a preferred embodiment of Applicants&#39; invention. An exemplary implementation is described below and depicted with reference to the drawings comprising a solid waste comminuting apparatus shown in one exemplary size and configuration. While the invention is described by way of this one embodiment, it is understood that the description is not intended to limit the invention to such embodiment, but is intended to cover alternatives, equivalents, and modifications which may be broader than the embodiments, but which are included within the scope of the appended claims.  
         [0018]     In an effort to prevent obscuring the invention at hand, only details germane to implementing the invention will be described in great detail, with presently understood peripheral details being incorporated by reference, as needed, as being presently understood in the art.  
         [0019]     According to a preferred embodiment of the present invention, a solid waste comminuting apparatus is generally designated with reference numeral  16  in  FIGS. 1-7 . Comminuting apparatus  16  is provided within a thermoforming trim system  10  that forms a downstream portion of a thermoforming line (not shown) in which individual articles are heat formed within a sheet, or web,  22  of thermoformable plastic material. Comminuting apparatus  16  includes design improvements that enable delivery of solid waste material from multiple locations during a thermoforming operation.  
         [0020]     As shown in  FIG. 1 , comminuting apparatus  16  is positioned at a downstream end of a thermoforming operation, beneath a thermoforming trim press  14 . Trim press  14  receives a web  22  having thermoformed articles  20  contained therein which are delivered by way of a canopy  12  into trim press  14  for severing and separation of articles  20  from web  22 . Articles  20  are then ejected toward a packaging table  18  where they are reviewed by an operator to identify any rejected products.  
         [0021]     Trim press  14  includes a plurality of female dies  38  and male dies  40  that coact to sever articles  20  from web  22 . More particularly, pairs of kinematic linkages  42  move a platen with male dies  40  toward and away from female dies  38  during such severing operation. Such a trim press  14  further includes a treadle system (not shown) that accurately conveys, guides and locates articles  20  relative to dies  38  and  40 . Additionally, canopy  12  includes an overhead conveyor system that includes a servo pick assembly  24  and a servo helper assembly  26  that cooperate along opposite edges of web  22  to move web  22  and articles  20  into position for trimming between dies  38  and  40 . Further details of the canopy and treadle of trim press  14  are disclosed in U.S. patent application Ser. No. 09/686,714, entitled “Apparatus for Conveying, Guiding and Locating a Thermoformable Web”, filed Oct. 10, 2000, by inventor Jere F. Irwin, now U.S. Pat. No. ______, which is herein incorporated by reference.  
         [0022]     In operation, servo motors are used to drive trim press  14  as well as the conveyor of canopy  12  such that primary servo drive  24  cooperates with secondary servo drive  26  to deliver articles  20  accurately between dies  38  and  40 , whereas servo motors drive a platen on which female dies  38  are mounted for timely and accurately severing articles  20  from web  22 .  
         [0023]     After being severed from a web, articles  20  are successively stacked and accumulated onto a table surface  28  of packaging table  18 . An operator can then inspect individual articles  20  to identify inferior quality products that are determined to be “rejected” products. An operator can then hand remove such “rejected” products and place such products onto a scrap conveyor  30 . Scrap conveyor  30  is driven via a transfer case using a constant-speed drive motor  34 . A conveyor belt (not shown) on drive and idler rollers extends into a conveyor cover  36  to deliver such “rejected” product back into comminuting apparatus  16  by way of a product entrance chute  48  that communicates with conveyor cover  36 .  
         [0024]     Concurrently, or alternately, a skeleton web (a web with articles removed)  22  is then delivered into comminuting apparatus  16  by way of skeleton web entrance chute  44 . Also concurrently or alternately, additional product can be received into a start-up formed web entrance chute  46  that enables entry of start-up formed web (including articles) for delivery directly from a thermoforming machine at start-up or when an imperfection is detected in the forming operation. In this manner, the start-up formed web does not pass through canopy  12  and trim press  14 , but instead passes directly into comminuting apparatus  16 , underneath trim press  14  and above a ballast tank  43 .  
         [0025]     Trim press  14  is affixed atop ballast tank  43  to stabilize trim press  14 . Ballast tank  43  is preferably filled with gravel or weighted material and attaches to a frame that supports trim press  14 . Ballast tank  43  acts to stabilize thermoforming trim system  10  and reduce or minimize any vibration or movement of the trim press during operation. Additionally, used lubricating oil can be accumulated within ballast tank  43  as it is generated during a thermoforming operation from lubrication of components that are in motion.  
         [0026]     As shown in  FIG. 1 , comminuting apparatus  16  is provided with three distinct entrance chutes (or ducts); namely, skeleton web entrance chute  44 , start-up formed web entrance chute  46 , and rejected product entrance chute  48 . In order to enable concurrent (as well as alternate) feeding of solid waste material into apparatus  16 , it was discovered that a divider plate, or bulkhead,  50  was advantageous in order to reduce clogging and misfeeding when providing scrap web and articles for comminuting within comminuting apparatus  16 .  
         [0027]     As shown in  FIG. 7 , entrance opening  45  in general enclosure  58  communicates with skeleton web entrance chute (or duct)  44 . Chute  44  is provided between back wall  72 , bulkhead  50 , and side walls  66  (see  FIG. 2 ) and  68 .  
         [0028]     Entrance opening  47  is provided in general enclosure  58  to communicate with start-up formed web entrance chute  46 . Chute  46  is provided between bulkhead  50 , cross-member  124  along with front wall  70 , and side walls  66  (see  FIG. 2 ) and  68 . A bottom edge of bulkhead  50  and mouth  94  cooperate to provide communication passages  144  and  146 , respectively. As start-up formed web is delivered into entrance opening  47 , the web moves downwardly in chute  46  until engaging with fingers  142  of feed roll  52 . The formed web is drawn via passages  144  and  146  outwardly along feed roll  52 , downwardly along an outer edge of feed roll  52 , and beneath feed roll  52  for delivery and severing between the pair of scissor rolls (see  FIG. 6 ).  
         [0029]     Entrance opening  49  is provided in general enclosure  58  which enables communication of rejected article chute (or duct)  48  with chutes  44  and  46 . Mouth  94  enables individual articles  20  (as shown in  FIG. 7 ), to pass in an unobstructed manner within general enclosure  58  for engagement with fingers  142  so as to be drawn downwardly beneath feed roll  52  for delivery below and to the pair of scissor rolls (see  FIG. 6 ). It was discovered that the specific configuration of bulkhead  50 , including mouth  94  and the respective bottom edge, facilitated passage of rejected articles  20  from chute  48  into the general enclosure without unduly obstructing and clogging entrance chute  44  because articles  20  would otherwise engage in and pile up against bulkhead  50 . The presence of bulkhead  50  is needed in order to separate entrance chutes  44  and  46  such that introduction of start-up formed web material into chute  46  does not further obstruct the line-speed delivery of a skeleton web via entrance chute  44 . Accordingly, it has been found that multiple entrance openings can be provided with multiple entrance chutes to provide for recycling and comminuting of different webs and rejected articles concurrently, as well as serially, while operating a single comminuting apparatus.  
         [0030]     Mouth  94  provides a cleft along a lower edge of bulkhead  50 . Alternatively, an opening or aperture can be provided. Further optionally, bulkhead  50  can comprise a baffle plate that is elevated above entrance opening  49 .  
         [0031]     In operation, bulkhead  50  subdivides an interior of comminuting apparatus  16  (within enclosure  58 ) such that skeleton web entrance chute  44  is separated from start-up formed web entrance chute  48 . Furthermore, an opening or mouth  94  (see  FIGS. 2 and 7 ) is provided in bulkhead  50  such that articles  20  delivered on conveyor  30  through entrance chute  48  do not impinge against bulkhead  50  and become obstructed, but can pass from chute  44  into chute  46  during comminuting of such rejected product (or articles) to facilitate delivery to feed roll  52 .  
         [0032]     It is understood that bulkhead  50  can be incorporated on any of a number of differently designed comminuting apparatus. One such design shown in the present preferred embodiment includes a feed roll  52  and a pair of intermeshing scissor rolls  54  and  56 . Further details of such a construction (but without bulkhead  50  and the entrance openings) have previously been disclosed in U.S. Pat. No. 5,893,523, issued Apr. 13, 1999, entitled “Apparatus for Comminuting Waste Materials Having Feed Roll Delivery Features”, naming the inventor as Jere F. Irwin, and herein incorporated by reference. Another suitable alternative construction is disclosed in U.S. Patent Application Publication No. US2002/0190146 A1, entitled “Comminuting Apparatus and Pneumatic Recirculation Systems for Comminuting Apparatus”, naming the inventor as Jere F. Irwin, published Dec. 19, 2002, and herein incorporated by reference. Further alternative constructions for comminuting apparatus can also benefit from the incorporation of bulkhead  50  in the features of the present invention.  
         [0033]     As shown in  FIGS. 2-7 , bulkhead  50  is configured between entrance chutes  44  and  46  so as to subdivide an interior of a general enclosure  58  of comminuting apparatus  16 . In one case, bulkhead  50  is formed from a piece of formed and zinc-coated sheet steel. Also in one case, bulkhead  50  comprises a baffle that is cambered, or curved, in edge view to facilitate directional entry of waste material from entrances  44  and  46 . As shown in  FIGS. 2 and 7 , a mouth  94  is provided along a bottom edge of bulkhead  50  at a location that enables delivery of rejected articles from entrance chute  48  into the interior of comminuting apparatus  16 . This configuration reduces or eliminates jamming or clogging of rejected articles against bulkhead  50 . Clogging becomes a consideration, particularly when articles  20  (see  FIG. 7 ) are relatively long and exceed the distance between entrance opening  49  and bulkhead  50 .  
         [0034]     General enclosure  58  is formed by a general frame  60  which receives a top wall  62 , a bottom wall  64 , side walls  66  and  68 , front wall  70 , and back wall  72 . Details of such walls are shown respectively in  FIGS. 2-5 .  
         [0035]     In operation, comminuting apparatus  16  is configured to receive solid waste material from one of entrance chutes  44 ,  46 , and  48  (of  FIG. 1 ), with the solid waste material being fed around and beneath feed roll  52  for subdividing beneath and between scissor rolls  54  and  56 . Where the solid waste material is delivered via chutes  44 ,  46 , or  48 , the solid waste material is delivered out and around feed roll  52  by way of fingers  142  (see  FIG. 6 ).  
         [0036]     Depending on a specific application, apparatus  16  may be self-supported beneath a trim press, or affixed to the trim press or packaging table. In the present case, trim press  14  is affixed to packaging table  18  via article conveyor  30  and conveyor cover  36  which are both secured to apparatus  16  using a plurality of fasteners. Alternatively, they can be welded together.  
         [0037]     As shown in  FIGS. 4 and 5 , back wall  72  supports a downstream end of conveyor  30 , with conveyor  30  being secured to back wall  72  using a plurality of threaded fasteners. Furthermore, conveyor cover  36  is secured to back wall  72  using such fasteners. Hence, recycle product entrance chute  48  extends through conveyor cover  36  to pass through back wall  72  and into the interior of apparatus  16 . As shown in  FIG. 2 , such entrance chute is defined by a rectangular entrance opening  49  provided in back wall  72 .  
         [0038]     As shown in  FIGS. 2-5 , frame  60  of apparatus  16  is supported on four legs  78 , each of which has a pair of wheels  80 , with one leg  78  provided at each corner of apparatus  16 . Frame  60  includes walls  62 ,  64 ,  66 ,  68 ,  70 , and  72 , cross-members  122  and  124  (see  FIG. 6 ), and backing plates  128  and  130  (see  FIG. 6 ). Furthermore, in order to support bulkhead  50 , a pair of edge frame members  74  and  76  are provided on opposite edges of bulkhead  50  and are welded onto frame  60  by welding members  74  and  76  to side walls  66  and  68 , respectively.  
         [0039]     As shown in  FIG. 6 , the pair of scissor rolls  54  and  56  are mounted in an intermeshing relationship for rotation in opposite directions, or co-rotation. Scissor rolls  54  and  56  operate in coordination with each other so as to receive and subdivide solid waste material as it is delivered via feed roll  52  to scissor rolls  54  and  56 . More particularly, feed roll  52  includes a plurality of feed fingers  142  that grab and draw solid waste material around and under feed roll  52  for delivery to scissor roll  54 . Scissor roll  54  draws the solid waste material underneath, toward and between scissor rolls  54  and  56 . Such material is then subdivided as it is drawn from an entrance nip beneath and between scissor rolls  54  and  56  upwardly toward an exit nip between and above scissor rolls  54  and  56 . Finger knives  140  on each scissor roll  54  and  56  intermesh and serve to subdivide and comminute the solid waste material. Spacer rings  138  are provided between adjacent scissor rings  136  on each of scissor rolls  54  and  56 . By alternating the scissor rings  136  and spacer rings  138  and offsetting them between scissor rolls, intermeshing action occurs between adjacent finger knives  140 . A stripper finger  132  and  134  rides along each spacer ring  138  on each scissor roll  54  and  56 , respectively, to clean subdivided scrap material from the scissor rolls.  
         [0040]     Each stripper finger  132  and  134  is carried by a respective frame cross-member  122  and  124 . After material is drawn up between scissor rolls  54  and  56 , the material accumulates and cascades over frame cross-member  122  where it is further delivered to feed roll  52  to be further drawn around feed roll  52  and down to scissor roll  54  for further subdividing and/or sorting along separator screen  116 .  
         [0041]     As material of a sufficiently small size is passed through separator screen  116 , such material falls into a shear outtake plenum (or manifold)  118  where it is drawn via an outlet  120  using a pneumatic conveyor  96  (see  FIG. 2 ).  
         [0042]     A feed plate  126  includes slots in which each individual finger  142  on feed roll  52  passes so as to meter, punch and draw material along scissor feed roll  52  down along a backing plate  128  and towards scissor roll  54 . Backing plate  128  is formed from a plurality of welded pieces of bar stock material that are edge-welded together in order to provide a curved cylindrical shape. Likewise, another backing plate  130  is provided along and beneath scissor roll  56  comprising a plurality of bar stock components that are edge-welded together.  
         [0043]     As shown in  FIG. 6 , a bottom edge of bulkhead  50  is raised elevationally above feed roll  52  a sufficient height such that start-up formed web material that is received within entrance chute  46  can be captured and grabbed by fingers  142  on feed roll  52 . The captured scrap material then passes underneath bulkhead  50  and outwardly and downwardly around feed roll  52  for delivery underneath feed roll  52  and towards scissor rolls  54  and  56 .  
         [0044]     As shown in  FIGS. 2, 3  and  5 , an electric drive motor  82  drives a pair of right angle gear boxes  84  and  86  that respectively drive shafts  92  and  88  (see  FIG. 3 ) of scissor roll  56  and feed roll  52 , respectively. As shown in  FIG. 4 , a gear case  106  (beneath the housing) includes a pair of identically sized intermeshing gears  108  and  110  that couple together shafts  90  and  92  of scissor rolls  54  and  56 , respectively (see  FIG. 6 ). Accordingly, gears  108  and  110  drive the pair of scissor rolls in co-rotation, but in opposite directions.  
         [0045]     In order to withdraw sorted and subdivided plastic waste material from comminuting apparatus  16 , pneumatic conveyor  96  is provided externally of enclosure  60 . Pneumatic conveyor  96  includes a centrifugal fan  98  that is driven by a constant-speed electric motor  100 . A product outlet  102  is provided on a fan housing of centrifugal fan  98  such that materials are withdrawn pneumatically by way of product outlet  120  into an outlet tube (not shown) for collection in a cannister (not shown). Further details of such construction are disclosed in U.S. Pat. No. 5,893,523 and U.S. Patent Application Publication No. US2002/0190146 A1, both previously incorporated by reference. A shear outtake pipe  104  (see  FIGS. 2 and 4 ) draws material from outlet  120  for delivery through pneumatic conveyor  96  and ejection through product outlet  102 . Accordingly, pneumatic conveyor  96  generates a vacuum that draws sorted and subdivided material from shear outtake plenum  118 , as shown in  FIG. 6 .  
         [0046]     With regard to motor  80 , a belt cover (or guard)  112  houses a lugged timing belt  114  which enables motor  82  to drive a shaft  115  that further drives gear boxes  84  and  86  to respectively drive shafts  92  and  88 , respectively.  
         [0047]     According to one construction, drive motor  82  is a continuous speed drive motor sold by Baldor Electric Company of Fort Smith, Ariz., comprising a four-pole, synchronous, 20 hp, 1800 rpm, 230/460 VAC motor. Also according to one construction, gear boxes  84  and  86  each comprise right angle, worm drive gear boxes having input shafts that are connected using a flexible coupling. In the case of gear box  86 , the gear box is a churn gear box having a ratio of 25:1; whereas, the gear box  84  provides the scissor roll gear box having a ratio of 7.5:1. Gear box  86  rotates clockwise; whereas, gear box  84  rotates counter-clockwise, as viewed in  FIG. 3 .  
         [0048]     As shown in  FIG. 4 , chute  44  originates in an entrance opening  45 , whereas chute  46  originates in an entrance opening  47 . Similarly, chute  48  corresponds with an entrance opening  49 , as shown in  FIG. 7 . Furthermore,  FIG. 7  also illustrates the relative positionings of entrance openings  45 ,  47  and  49  with respect to chutes  44 ,  46  and  48 , respectively.  
         [0049]      FIG. 5  illustrates, in partial breakaway view, entrance chutes  44 ,  46  and  48 . Top wall  62  is shown partially removed in order to view the relative positions of scissor rolls  54  and  56 . Frame cross-members  122  and  124  are also shown supporting stripping fingers  132  and  134 , respectively. The arrangement of fingers  142  can clearly be seen on feed roll  52 . Each finger  142  is received within a respective slot in feed plate  126 .  
         [0050]     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.