Abstract:
An apparatus and methods for mixing and injecting a foam core within an extruded shell preferably of plastic downstream from an extrusion die to produce a uniform building product. The preferred apparatus includes a mixing head injector for mixing a binary system foam. The mixing head injector incorporates pressurized gas injection for homogenization of the foam core. A preferred method employs the mixing head injector and a novel calibrator thereby allowing injection of a foam core within the shell as it passes through a calibrator to reliably produce a uniform building product. An alternative method employs a second extruder. Alternative methods employ a mounting fixture downstream of a first calibrator.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This is a division of application Ser. No. 09/860,939, filed May 18, 2001, now U.S. Pat. No. 6,592,789 granted Jul. 17, 2003. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable 
   REFERENCE TO A MICROFICHE APPENDIX 
   Not Applicable 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a novel apparatus and methods for the forming of a building material that may replace more expensive materials or materials that are more limited in supply. The preferred method begins with an extruder with an extrusion die that produces an extruded shell preferably of plastic that may have various profiles but each shell has an open gap preferably formed in its top working surface between spaced and parallel edges of the shell. The shell is then conducted into and through a calibrator where a vacuum is applied to the exterior of the shell to maintain the shape of the shell as it passes through the calibrator. The calibrator has an injection bore that in the preferred embodiment allows the inserting of an injector nozzle of a mixing head injector into and through the injection bore, through a gap in the extruded shell, and into a central shell cavity of the extruded shell as the shell passes through the calibrator. In the preferred embodiment, the mixing head injector mixes and injects a foam core through its injector nozzle and through the injection bore to fill the central shell cavity and the gap downstream from the injector nozzle as the shell passes by the injection bore. The core expands and cures as the shell and core continue through the remainder of the calibrator. 
   2. Description of Related Art 
   A number of extrusion devices exist that can aid a person in understanding the art of extrusion and foam filled extrusions. In U.S. Pat. No. 5,783,125 issued to Bastone is disclosed reinforced extrusion products and method of making same. In U.S. Pat. No. 5,393,536 issued to Brandt, a coextrusion apparatus is addressed. These prior devices use a different apparatus for the mixing and injection of a central core and introduce the central core through the extrusion die rather than downstream as done in the present invention. 
   In U.S. Pat. No. 6,083,601 issued to Prince, a foam wood extrusion product is disclosed that is formed by the extrusion first of a foam core that then receives a coextruded plastic cladding. 
   BRIEF SUMMARY OF THE INVENTION 
   A principal objective of this invention is to provide a novel and improved mixing head injector and a method for mixing and injecting a foam core within an extruded shell preferably of plastic having a central shell cavity and having an open gap. The foam core injection takes place downstream from an extrusion die and preferably while the shell passes through a calibrator resulting in a foam filled shell as the shell exits the calibrator. The preferred mixing head injector of the invention is novel, compact, simple, low-maintenance, and reliable for mixing a binary system foam core such as polyurethane or other suitable synthetic binary foam known in the art. Gas injection is incorporated in the mixing head injector for homogenization of the foam core. Preferably the mixing head injector is mounted in an injection bore of a calibrator. The foam core is injected from the mixing head injector into a central shell cavity through a gap in the shell and thereafter the core cures as the shell and core continue through the remainder of the calibrator. 
   A suitable plastic for the extruded shell is ASA commercially available in pellet form from Hughes Processing Incorporated of Costa Mesa, Calif. 
   In an alternative embodiment, the mixing head injector is replaced by a second extruder. The second extruder having an extruder port extrudes a foam core comprising a selected mixture of synthetic, plastic foam known in the art containing at least one filler selected from a group of fillers including glass spheres, wood flour, fly ash, chopped strand materials, or similar inert materials through the extruder port. Suitable blowing agents for the selected plastic foam as known in the art would be used with the second extruder. The foam core would be extruded into the central shell cavity of the extruded shell as it passes by the extruder port. The extruder port of the second extruder would be mounted into and through the injection bore of the calibrator. 
   In alternative methods, the injection of a foam core by the mixing head injector or the second extruder within the central shell cavity of an extruded shell can occur after the shell exits the calibrator. In such alternative methods, the shell is conveyed into and through a suitable mounting fixture and the mixing head injector or the second extruder is mounted in the mounting fixture. Preferably the mounting fixture has a mounting fixture bore in which the injector nozzle of the mixing head injector or extruder port of the second extruder can be mounted and the foam core is injected through the mounting fixture bore and into the central shell cavity through the gap in the shell as the shell passes through the mounting fixture and thereafter the core cures as the shell and core continue through the remainder of the mounting fixture. The mounting fixture can be a second calibrator. 
   A further object of the invention is to provide a timesaving and economical method and apparatus for the production of a foam filled extruded building material. 
   Additional and various other objects and advantages attained by the invention will become more apparent as the specification is read and the accompanying figures are reviewed. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       FIG. 1A  is a side schematic view showing an extrusion and calibrator line with a mixing head injector; 
       FIG. 1B  is a side schematic view showing an alternative extrusion and calibrator line with a second extruder; 
       FIG. 2A  is a side schematic view showing an alternative extrusion and calibrator line with a mounting fixture and a mixing head injector; 
       FIG. 2B  is a side schematic view showing an alternative extrusion and calibrator line with a mounting fixture and a second extruder; 
       FIG. 3  is a view of the mixing head injector and calibrator as viewed from direction  3 — 3  in  FIG. 1A ; 
       FIG. 4  is a sectional view of the mixing head injector and calibrator along the line  4 — 4  in  FIG. 3  without the foam components and the foam core shown; 
       FIG. 5  is a side elevational view of the central stem of the mixing head injector; 
       FIG. 6  is a sectional view of the mixing head injector along the line  6 — 6  in  FIG. 4 ; 
       FIG. 7  is a detail view from  FIG. 4 ; 
       FIG. 8  is a cross sectional view of the calibrator and extruded shell along the line  8 — 8  in  FIG. 1A ; 
       FIG. 9  is a partial cross sectional view along the line  9 — 9  in  FIG. 1A ; and 
       FIG. 10  is a cross sectional view along the line  10 — 10  in FIG.  1 A. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1A , the present invention is novel and provides an extrusion and calibrator line comprising an extruder  6  that extrudes through an extrusion die  8  an extruded shell  10  having an open gap formed preferably in the shell&#39;s top working surface. The gap in the shell  10  exists between spaced and parallel first and second shell edges  12  and  14 . A central shell cavity  16  is located through the gap between the edges  12  and  14  and to the inside of the shell  10 . From the die  8 , the shell  10  passes into and through a calibrator  18  that cools and conditions the shell as it passes through the calibrator. The calibrator  18  has an injection bore  20  as shown in  FIGS. 1A ,  1 B,  4 , and  9  to which is mounted a mixing head injector  22  or alternatively a second extruder  24  as shown in FIG.  1 B. 
   Alternatively as shown in  FIGS. 2A and 2B , the extruded shell  10  exits the calibrator  18  and is conveyed into and through a suitable mounting fixture  26 . The mixing head injector  22  or the second extruder  24  can be mounted in a mounting fixture bore  21  of the mounting fixture  26 , said mounting fixture being downstream of the calibrator  18  and there inject a foam core after the shell  10  exits a first calibrator. The suitable mounting fixture  26  can be a second calibrator. 
   Tractor means  28  well known in the art such as pull rollers pull the shell  10  through the extrusion and calibration line. 
   The extrusion die  8  may be of various configurations to produce shells  10  with the desired cross-sectional profile. The shell cross-sectional profile may be rectangular, triangular, circular, polygonal, or other desired geometric shape. 
   Preferably the calibrator  18  has a low-friction coating  30  (which may be a Teflon™ coating) on at least its interior surface which is adjacent to the first and second shell edges  12  and  14  and through which the injection bore  20  passes. A mixing head injector  22  is snugly fitted and mounted in the injection bore  20 . Alternatively, a second extruder  24  may be mounted in the injection bore  20 . 
   In the preferred embodiment, the mixing head injector  22  has a cylindrical hollow case  32  as shown in  FIGS. 4 ,  6 , and  9 . The case  32  has a closed end and an open end. At its closed end, the case  32  has an injector nozzle  34 . When mounted in the injection bore  20 , the injector nozzle  34  preferably protrudes through the injection bore  20  of the calibrator  18 , through the gap of a passing shell  10 , and opens into the central shell cavity  16 . The case  32  has a case wall bore  36  that passes preferably radially through the case near its open end away from the injector nozzle  34 . 
   An injector disc  40  is first mounted and nested in the case  32  as best shown in FIG.  4 . Preferably, the injector disc  40  has a funnel shaped bore  42  through it that communicates freely out from the interior of the case  32 , that passes through the injector nozzle  34 , and that funnels into the central shell cavity  16  of a passing shell  10 . A spiral sleeve  50  is next mounted and nested in the case  32  adjacent to the injector disc  40 . 
   The spiral sleeve  50  has a first end  52  that is away from the injector disc  40 . The spiral sleeve  50  has an interior threaded spiral ramp  54  along the sleeve&#39;s interior axial bore. The spiral ramp  54  defines an open spiral channel  56  along the sleeve&#39;s interior axial bore. The spiral channel  56  spirals from the first end  52  to meet and communicate with the funnel shaped bore  42  of the injector disc  40 . The spiral channel  56  is open to and exists along the interior axial bore of the spiral sleeve  50 . The interior axial bore of the spiral sleeve  50  and the funnel shaped bore  42  are preferably coaxial and the spiral channel  56  meets and communicates freely with the funneled shaped bore. 
   An annular spacer  60  with an interior axial bore is next mounted and nested in the case  32  adjacent and coaxially to the spiral sleeve  50 . The annular spacer  60  has an annular spacer groove  62  circumscribing its outer surface. One or more annular spacer groove bores  64  pass preferably radially from the annular spacer groove  62  and through the annular spacer  60 . Each annular spacer groove bore  64  allows free communication between the interior axial bore of the annular spacer  60  and the annular spacer groove  62 . The diameter of the interior axial bore of the annular spacer  60  is preferably larger than the diameter of the interior axial bore of the spiral sleeve  50 . 
   A case ring  66  with an interior axial bore preferably of the same diameter as the axial bore of the spiral sleeve  50  is next mounted adjacent and coaxially to the case  32  and the annular spacer  60 . A case ring bore  68  passes preferably radially through the case ring  66  and into its interior axial bore as best shown in FIG.  4 . 
   As best shown in  FIG. 4 , a central stem  70  is inserted into and throughout the axial bores of the case ring  66 , the annular spacer  60 , and the spiral sleeve  50 . Preferably the central stem  70  is inserted partially into the funnel shaped bore  42 . Preferably, the central stem  70  is close fitting in the axial bores of the case ring  66  and the spiral sleeve  50 . 
   Between the annular spacer  60  and the central stem  70  is a first annular space  72  in free communication with the spiral channel  56 , said spiral channel defined by the spiral sleeve  50 , the spiral ramp  54 , and the central stem  70 . Preferably, the central stem  70  has a tapered end  74  that partially extends into the funnel shaped bore  42  of the injector disc  40 . The tapered end  74  and the injector disc  40  define a funnel channel  44  which is in free communication with the spiral channel  56  and with the central shell cavity  16  of a shell  10  passing by the injection bore  20 . 
   Preferably, as shown in  FIGS. 4 and 5 , the central stem  70  has a shoulder  76  at its end away from the tapered end  74 . Preferably the shoulder  76  has a radius from the longitudinal axis of the stem  70  that is larger than the radius of the interior axial bore of the case ring  66 . The shoulder  76  helps seal the central stem  70  to the case ring  66 . 
   The central stem  70  has an outer axial stem bore  78  and an inner axial stem bore  80  as shown in  FIGS. 4 ,  5 , and  7 . The depth of the inner axial stem bore  80  into the stem  70  is greater than the depth of the outer axial stem bore  78 . 
   When the mixing head injector  22  is assembled, the outer axial stem bore  78  coaxially extends fully through the axial bores of the case ring  66  and of the annular spacer  60  and coaxially extends partially into and along the axial bore of the spiral sleeve  50 . The central stem  70  has an inner axial stem bore  80  of smaller diameter than the outer axial stem bore  78  that coaxially extends further than the outer axial stem bore into and along the axial bore of the spiral sleeve  50  as best shown in  FIGS. 4 and 6 . 
   The central stem  70  has a first annular stem groove  82  circumscribing the stem. Between the first annular stem groove  82  and the case ring  66  is a second annular space  84 . The case ring bore  68  allows free communication into the second annular space  84 . A first annular stem groove bore  86  passes preferably radially from the first annular stem groove  82  and into the outer axial stem bore  78  and allows free communication between the first annular stem groove and the outer axial stem bore. The first annular stem groove  82  is preferably near the shoulder  76 . 
   The central stem  70  has a second annular stem groove  88  circumscribing the stem immediately adjacent the spiral ramp  54  and located below the first end  52  of the spiral sleeve  50 . A plurality of second annular stem groove bores  90  pass preferably radially from the second annular stem groove  88  and into the outer axial stem bore  78  and allow free communication from the outer axial stem bore into the second annular stem groove. The second annular stem groove  88  is in immediate communication with the spiral channel  56 . 
   The central stem  70  has a third annular stem groove  92  circumscribing the stem immediately adjacent the spiral ramp  54  and located below and downstream of the second annular stem groove  88 . A plurality of third annular stem groove bores  94  pass preferably radially from the third annular stem groove  92  and into the inner axial stem bore  80  and allow free communication from the inner axial stem bore into the third annular stem groove. The third annular stem groove  92  is in immediate communication with the spiral channel  56 . 
   A central gas pipe  100  extends coaxially through a pipe fitting  102  and throughout the length of the outer axial stem bore  78 . The pipe fitting  102  sealingly fits the central gas pipe  100  into the outer axial stem bore  78  in a manner well understood in the art as best shown in FIG.  4 . The central gas pipe  100  preferably has the same diameter as the inner axial stem bore  80  and is press fit into the upper portion of the inner axial stem bore  80  thereby isolating the lower portion of the inner axial stem bore from the outer axial stem bore  78 . As shown in  FIGS. 4 and 7 , the central gas pipe  100  stops short and clear of a plurality of third annular stem groove bores  94  located in the lower portion of the inner axial stem bore  80 . The central gas pipe  100  communicates through the inner axial stem bore  80 , the third annular stem groove bores  94 , and into the third annular stem groove  92 . 
   A case cap  104  is fitted atop the case ring  66 . The case cap  104  secures the central stem  70  in the axial bore of the case ring  66 . The case cap  104  has a case cap bore  106  that is coaxial to the outer axial stem bore  78 . The central gas pipe  100  and the pipe fitting  102  pass through the case cap bore  106 . Preferably, the case cap  104 , the case ring  66 , and the case  32  are secured together by a plurality of case bolts  108  in a manner well understood in the art. 
   A first component conduit  110  communicates through a first component conduit fitting  112  into the case wall bore  36 . The first component conduit fitting  112  sealingly fits the first component conduit  110  into the case wall bore  36  in a manner well understood in the art as best shown in FIG.  4 . 
   A second component conduit  120  communicates through a second component conduit fitting  122  into the case ring bore  68 . The second component conduit fitting  122  sealingly fits the second component conduit  120  into the case ring bore  68  in a manner well understood in the art as best shown in FIG.  4 . 
   Preferably the injector disc  40 , the spiral sleeve  50 , the spiral ramp  54 , and the central stem  70  are all fabricated from solid Teflon™ or other non-stick plastic material. As well known in the art, O-rings can be used in the mixing head injector  22  to keep undesired leakage through close fitting parts under control. 
   In the preferred embodiment, primary mixing of a foam core  130  occurs in a spiral channel  56  defined by a spiral ramp  54  along the interior bore of a spiral sleeve  50  that coaxially surrounds a central stem  70 . First delivery means such as a reservoir of component one of a foam connected to a pump and connected to a first component conduit  110  for controlled delivery of component one supplies the mixing head injector  22  with component one. Second pumping means such as a reservoir of component two of a foam connected to a pump and connected to a second component conduit  120  for controlled delivery of component two supplies the mixing head injector  22  with component two. Third pumping means such as a reservoir of gas connected to a pump and connected to a central gas pipe  100  for controlled delivery of pressurized gas supplies the mixing head injector with homogenizing gas, preferably air. 
   Component one is pumped through a first component conduit  110  into a case wall bore  36 , then into an annular spacer groove  62  and then through one or more annular spacer groove bores  64  and into a first annular space  72  that is in direct communication with a spiral channel  56  at a first end  52  of a spiral sleeve  50 . 
   Component two is pumped through a second component conduit  120  into a case ring bore  68  and then into a first annular stem groove  82 , then through one or more first annular stem groove bores  86 , then into an outer axial stem bore  78  and then through a plurality of second annular stem groove bores  90  and into a second annular stem groove  88  and then into direct communication with component one in a spiral channel  56 . 
   The second annular stem groove  88  is in immediate communication with the spiral channel  56  throughout nearly the entire circumference of the second annular stem groove and thus greatly improves the mixing of component two with component one. The foam core  130  then is injected with an homogenizing gas through a central gas pipe  100  mounted in an inner axial stem bore  80  of the central stem  70 . The gas exits the inner axial stem bore  80  through a plurality of third annular stem groove bores  94  in the central stem  70  and into a third annular stem groove  92  and then into the mixing components one and two in the spiral channel  56 . 
   The spiral channel  56  conveys the mixing components into a funnel channel  44  that is preferably defined by a tapered end  74  of the central stem  70  and a funnel shaped bore  42  in an injection disc  40 . The funnel channel  44  then conveys the foam core  130  through the injection disc  40  and allows the passage of the foam core out of the mixing head injector  22  through an injector nozzle  34  and into a central shell cavity  16  of a passing shell  10 . The foam core  130  substantially fills the central shell cavity  16  and the gap between edges  12  and  14  of the shell  10  after the shell passes the injector nozzle  34 . Preferably, the foam core  130  cures as the foam core progresses with the shell  10  through the remainder of the calibrator  18 . 
   A further object of this invention is providing an apparatus and method of injecting a foam core  130  into a shell  10  while the shell passes through a calibrator  18  downstream of the extrusion die  8  in an extrusion and calibrator line resulting in a uniform foam core building material. In the preferred embodiment, the foam core  130  is injected through an injector nozzle  34  of a mixing head injector  22  and through an injection bore  20  in a calibrator  18  and through a gap in a shell  10  as it passes through the calibrator  18 . 
   The present invention provides in the preferred embodiment, a new mixing head injector  22  mounted in an injection bore  20  of a calibrator  18  to inject a foam core  130  in an extruded shell  10  to produce a uniform building product in a continuous process. Alternatively, a second extruder  24  can be used to inject a foam core  130  or some other foamed core. Alternatively, as best shown in FIG.  2 A and  FIG. 2B , the mixing head injector  22  or a second extruder  24  can be mounted in a mounting fixture  26  downstream of a first calibrator  18 . 
   The preceding description and exposition of the invention is presented for purposes of illustration and enabling disclosure. It is neither intended to be exhaustive nor to limit the invention to the precise forms disclosed. Modifications or variations in the invention in light of the above teachings that are obvious to one of ordinary skill in the art are considered within the scope of the invention as determined by the appended claims when interpreted to the breath to which they are fairly, legitimately and equitably entitled.