Abstract:
A molding system for forming an article of composite material including a track, a mold supported on the track, the mold defining a mold cavity, an injection tube supported adjacent the mold and in fluid communication with the mold cavity, the injection tube being fluidly connected to a source of the composite material, wherein the composite material is fed into the mold cavity via the injection tube and wherein the mold is adapted to move injection tube as the composite material is fed into the mold progressively increasing the volume of the mold cavity.

Description:
RELATED PATENT APPLICATIONS 
   None. 
   TECHNICAL FIELD 
   The present invention generally relates to a molding system using a mold apparatus to form an elongate article of polymeric material reinforced with tire pieces. More particularly, the present invention relates to a molding system using a mold apparatus configured to form an elongate article from a slurry of polymeric material and tire pieces, where the elongate article has high rigidity and good durability. More specifically, the present invention relates to a molding system using a mold apparatus having a variably-sized mold cavity, where the length of an elongate article formed by the mold apparatus is proportional to the amount of slurry that enters the variably-sized mold cavity. 
   BACKGROUND OF THE INVENTION 
   The disposal of scrap or used tires poses a serious threat to our environment. Unlike other waste products, tires do not readily break down in air or soil. It has been estimated that three billion tires have been discarded into U.S. dumps and land fills. Often, whole tires are simply piled onto vacant space within the dump, creating an eyesore. There, the inner cavities of these tires collect rain water and provide a breeding ground for mosquitoes. As a further hazard, the discarded tires in these piles are often worn to the point where their reinforcing wires are exposed. The exposed wire can injure persons handling the tires or children that attempt to climb the piles. 
   In other instances, the tires are buried. However, chemical reactions between the tires, soil, and air trapped in the inner cavities can create sufficient heat to ignite the tires, creating a dangerous fire hazard. For these reasons, there have been many attempts to recycle tires into useful products. 
   Attempts to recycle and reuse tires have focused on several techniques, including reclaiming the rubber from the tires through chemical processes, ultrasonic devulcanization, and grinding. Thereafter, the reclaimed rubber is mixed with other components during subsequent processing. However, each of these reclaiming techniques requires that the non-rubber materials, such as the metal belts used in belted tires, be removed from the tires before processing can begin. Consequently, each of these reclaiming techniques can be complicated and costly. Consequently, it is desirable to recycle and reuse tires without separating the rubber from the non-rubber materials. 
   U.S. Pat. No. 6,583,211 describes a process where pieces of cut tires are combined with thermosetting material, thermoplastic material, or mixtures thereof, in a mold to produce a composite material having high rigidity. For example, the tire pieces are mixed with liquified thermosetting and/or thermoplastic materials to form a flowable melt of composite material which is subsequently molded into a desired shape. 
   Because such tire pieces damage extrusion and injection molding dies when the flowable melt is flowing therethrough, fixed-size molds have been necessary to shape the composite material. These fixed-size molds are closed upon filling to allow the material therein to set. As the material sets, significant pressures are developed inside the mold. These fixed-size molds are able to form the composite material into inexpensive, useful articles. But as their name suggests, these fixed-size molds are fixed in shape and volume, and new molds must be provided to produce differently sized articles 
   Consequently, if the composite material is used in making an elongate article such as an elongate beam, a mold must be provided that is at least as long as the desired length of the elongate beam. For example, if the mold is longer than the desired length of the elongate beam, then the resulting elongate beam can be cut to length. However, if the mold is shorter than the desired length of the elongate beam, then a new mold must be provided to accommodate the desired length of the elongate beam. Either way, material may be wasted or a new mold must provided. Moreover, articles of greater size produce higher pressures within the fixed-size molds, to the point that, large articles (including elongate beams) cannot be contained without causing such fixed-size molds to break. 
   As such, there is a need for molding process used to mold elongate articles formed from a composite materials including tire pieces that overcomes the deficiencies of molding processes using fixed-size molds. 
   SUMMARY OF THE INVENTION 
   To that end, a molding system including a variably-sized mold cavity, wherein the volume of the cavity increases proportionately to the amount of composite material that enters the mold is proposed. As such, desired length for an elongate article can be provided without having to provide different molds. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a plan view of a molding system according to the present invention including a slurry injection tube that provides a flowable melt of composite material reinforced with tire pieces into a mold that is moveable relative to the slurry injection tube to define a variably-sized mold cavity, where the molding system is depicted in a position where a relatively small amount of composite material has entered the mold; 
       FIG. 1B  is a plan view of the molding system according to the present invention similar to  FIG. 1A , where additional composite material has entered the variably-sized mold cavity, thereby displacing the mold further outward relative to the slurry injection tube; 
       FIG. 2A  is a cross-sectional view of a track supporting the mold and a back stop of the mold taken along line  2 A- 2 A of  FIG. 2B ; 
       FIG. 2B  is a partially fragmented cross-sectional view of the track and the mold supported by the track, where the variably-sized mold cavity is relatively small; and 
       FIG. 2C  is a partially fragmented cross-sectional view of the track and the mold supported by the track, where the variably-sized mold cavity is relatively large. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The molding system according to the present invention is generally indicated by the numeral  10  in the accompanying drawings. The molding system  10  may be used to produce an elongate article (preferably an elongate beam) formed of composite material such as a polymeric material reinforced with tire pieces. As such, in such a composite material, the polymeric material serves as the matrix of the elongate article throughout which the tire pieces are entrained. The molding system  10  includes a mold apparatus  11  which is adjustable to form an elongate article with a length proportional to the amount of slurry that is fed thereto. 
   Before entering the mold apparatus  11 , the polymeric material and tire pieces are mixed in a mixing apparatus  12  to form a flowable melt (or slurry) of composite material. The mixing apparatus  12  includes a mixing tube  14  to which a polymeric material feed assembly  15  and a tire-piece infeed chute  16  are connected. As such, the polymeric material in liquid form is fed by the polymeric material feed assembly  15 , and the tire pieces are fed by the tire-piece infeed chute  16 , into the mixing tube  14  to facilitate their combination. To that end, a mixer, such as a screw  18 , which extends through the interior of the mixing tube  14 , rotates to mix the liquified polymeric material and tire pieces together. After mixing of the liquified polymeric material and tire pieces, the slurry resulting therefrom is fed into the mold apparatus  11 . 
   The liquified polymeric material may be generated from raw polymeric material pellets in the polymeric material feed assembly  15 , and this liquified polymeric material is supplied to the mixing tube  14 . For example, the polymeric material feed assembly  15  includes a hopper  20  in which the raw polymeric material pellets are initially received. Ideally, the hopper  20  is conically-shaped to funnel the raw polymeric material pellets into a barrel  22 . 
   The barrel  22  is also part of the polymeric material feed assembly  15 , and includes a screw depicted in  FIGS. 1A and 1B  with the numeral  23 . The screw  23  supplies heat (via the friction generated through its rotation) to liquify the raw polymeric material pellets, and, simultaneously, pushes the liquified polymeric material out of the barrel  22 . The barrel  22  is connected to an outlet tube  24 , which, as seen in  FIGS. 1A and 1B , is connected to the mixing tube  14 . As such, the screw  23  forces the liquified polymeric material out of the barrel  22 , through the outlet tube  24 , and into the mixing tube  14 . 
   The tire pieces are fed to the mixing tube  14  using an infeed hopper  30  which is connected thereto. For example, the tire-piece infeed chute  16  supplies the infeed hopper  30  with tire pieces, and the infeed hopper  30  funnels the tire pieces into the mixing tube  14 . Before entering the infeed hopper  30 , the tire pieces are supplied to the tire-piece infeed chute  16  via a storage hopper  32 . The storage hopper  32  stores the tire pieces before the tire pieces are pushed by a screw depicted in  FIGS. 1A and 1B  with the numeral  33  through the tire-piece infeed chute  16 . 
   The tire pieces may be formed using any known process including a cutting or a shredding assembly (not shown). In fact, for improved material strength, tire pieces including reinforcing belt, cords, or wires may be used. The cutting or shredding assembly initially cuts whole tires into strips. To prepare such strips, it is not necessary to remove the metal reinforcing belts, cords, or wires, or other non rubber components commonly used in tires. Thereafter, the shredding assembly tears the strips into the tire pieces used to reinforce the elongate article. The tire pieces do not have to be any particular shape, and may be rectangular, circular, cubic, spheroidal, elongated, thread-like, or combinations thereof. While any size may be used, tire pieces sized to be larger than one (1) inch in at least one direction were found suitable in one application. 
   The infeed hopper  30  is attached to a first mixing tube inlet  36 , and the outlet tube  24  (of the polymeric material feed assembly  15 ) is attached to a second mixing tube inlet  38 . As seen in  FIG. 1 , the first mixing tube inlet  36  is positioned upstream of the second mixing tube inlet  38 , and both the first mixing tube inlet  36  and second mixing tube inlet  38  are positioned upstream of the mixing tube outlet  40 . The mixing tube outlet  40  is connected to the mold apparatus  11 , and therefore, after the liquified polymeric material and tire pieces are mixed in the mixing tube  14 , the resulting slurry is fed to the mold apparatus  11  through the mixing tube outlet  40 . 
   The mold apparatus  11  is configured to produce an elongate article with a length proportional to the amount of slurry which enters the mold apparatus  11  through the mixing tube outlet  40 . To that end, the mold apparatus  11  includes a mold  42  that moves relative to an injection tube to progressively increase the volume of the mold  42 . In the example shown, the mold  42  is axially moveable to form elongate articles. As shown in  FIGS. 1A ,  1 B, mold  42  may slide, in the mold apparatus  11 , on a track T to increase the size of a mold cavity  44  formed therein. As seen in  FIGS. 1A and 1B , the mold cavity  44 , in which the elongate article is formed, is partially defined by the interior of the mold  42 . As discussed below, the length of the mold cavity  44  (and, hence, the length of the elongate article formed therein) can depend on the location of the mold  42  relative to the track T. 
   The mold  42 , although having a square cross-sectional shape as seen in  FIG. 2A , can have any desired cross-sectional shape. As appreciated by those skilled in the art, varying the cross-sectional shape of the mold  42  will alter the cross-sectional shape of an elongate article formed therein. 
   As seen in  FIGS. 2A-C , the mold  42  includes a first end plate  46 , and, as seen in  FIGS. 1A and 1B , includes a second end plate  48  defining an aperture  50 . Both the first end plate  46  and second end plate  48  can have square shapes with approximately matching orientations. As discussed below, the four (4) corners of each the first end plate  46  and second end plate  48  ( FIGS. 1A and 1B ) are supported by the track T. As seen in  FIG. 2A , the mold  42  can include four (4) side walls  56 ,  57 ,  58 , and  59  that extend between the first end plate  46  and second end plate  48  ( FIGS. 1A and 1B ). In the example shown in  FIG. 2A , the four (4) side walls  56 ,  57 ,  58 , and  59  are arranged perpendicular with one another to form a box-like profile. These four (4) side walls  56 ,  57 ,  58 , and  59 , together with the first end plate  46  and second end plate  48 , define the interior of the mold  42 . As appreciated by those skilled in the art, the number of walls and their size will be dictated by a given application. Therefore, any number of walls may be used including a single wall. Thus, a single approximately cylindrical wall (or various pluralities of side walls) can be substituted for the four (4) side walls  56 ,  57 ,  58 , and  59  to produce elongate articles with various cross-sectional shapes. 
   The mold  42  is moveably supported (or carried) on the track T. As will be appreciated, any frame capable of supporting the mold  42 , and allowing it to move relative to the frame and/or a slurry injection tube  70  (as described more completely below) may be used in place of the track T. As depicted in  FIGS. 1A ,  1 B,  2 A,  2 B, and  2 C, the track T is fixed in position, and is formed from four (4) track members  64 ,  65 ,  66 , and  67  to accommodate the configuration of the mold  42 . The track members  64 ,  65 ,  66 , and  67  can be L-shaped rails ( FIG. 2A ) positioned at the corners of the mold  42 . As such, each of the track members  64 ,  65 ,  66  and  67  are configured to receive one of the four (4) corners of the first end plate  46  and second end plate  48  to allow the mold  42  to slide therealong. As appreciated by those skilled in the art, the track members  64 ,  65 ,  66 , and  67  could be provided with bearings to facilitate movement of the mold  42  on the track T. 
   Extending through the aperture  50  of the second end plate  48  into the interior of the mold  42 , is the slurry injection tube  70 . The slurry injection tube  70 , like the track T, may be fixed. As seen in  FIGS. 1A and 1B , the mixing tube outlet  40  is interconnected with one end of the slurry injection tube  70 . The other end of the slurry injection tube  70 , as discussed above, extends into the interior of the mold  42  through the aperture  50 . 
   As seen best in  FIGS. 2B and 2C , the distal end of the slurry injection tube  70  (which extends into the interior of the mold  42 ) includes an apertured flange  72 . The apertured flange  72  extends radially outward from the slurry injection tube  70 , and is sized slightly smaller than the interior of the mold  42 . To accommodate the configuration of the mold  42 , the slurry injection tube  70  includes four (4) edges  76 ,  77 ,  78 , and  79  which interface with and can seal against the interior surfaces of the side walls extending between the first end plate  46  and second end plate  48 . The aperture  80  formed in the apertured flange  72  defines the exit of the slurry injection tube  70 , and allows the slurry received in the slurry injection tube  70  from the mixing tube  14  (through the mixing tube outlet  40 ) to be injected into the interior of the mold  42 . 
   The slurry is pressurized upon entering the slurry injection tube  70  using, for example, a hydraulic ram  82 . The hydraulic ram  82  may reciprocate and is operatively connected to the slurry injection tube  70 , such that, when the hydraulic ram  82  intermittently reciprocates, slurry is pushed into the interior of the mold  42 . 
   Because the slurry is under pressure as it enters the interior of the mold  42 , the pressurized slurry forces the mold  42  to move along the track T away from the slurry injection tube  70  (to the left as seen in  FIGS. 2B and 2C ). In doing so, as seen in the difference depicted by  FIGS. 2B and 2C , the mold cavity  44  increases in length to accommodate more and more slurry. That is, the mold cavity  44 , defined as the area of the interior of the mold  42  bounded by the apertured flange  72 , changes in length (as the mold  42  moves relative to the slurry injection tube  70 ) according to the amount of slurry which exits the slurry injection tube  70 . Consequently, the mold cavity  44  is variably sized, and the length of the elongate article formed therein, is proportional to the amount of slurry that exits the slurry injection tube  70 . As such, the length of the elongate article is primarily constrained only by the length of the track T and mold  42 . 
   In light of the foregoing, it should thus be evident that a molding system according to the concepts of the present invention substantially improves the art. While, in accordance with the patent statutes, only the preferred embodiment of the present invention has been described in detail hereinabove, the present invention is not to be limited thereto or thereby. It will be appreciated that various modifications may be made to the above-described embodiment without departing from the spirit of the invention. Therefore, to appreciate the scope of the invention, reference should be made to the following claims.