Abstract:
In combination with a mixer/extruder of the type designed to mix, heat and extrude a mixture of shredded plastic material and shredded fibrous material, the heated mixture being extruded in the form of a continuous beam from an extrusion nozzle, the improvement which comprises a first matrix spaced horizontally downstream from the nozzle for receiving the beam therein and a second matrix spaced horizontally downstream from the first matrix for receiving the beam therein, the first matrix having a plurality of moveable walls which reciprocate in a horizontal direction against the outer surface of the beam, the second matrix having a plurality of moveable walls which reciprocate in a horizontal direction against the outer surface of the beam, the second matrix having means for conducting cooling water therethrough for cooling the beam as it passes through the second matrix.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to the field of producing shaped products from recycled plastic material, and more particularly to a method and apparatus for extruding shaped products from plastic material, particularly recycled materials including plastic. 
     2. The Prior Art 
     Plastic materials are sometime recycled by carefully sorting one type of refuse material from another, and ultimately producing granules of pure plastic of a particular type or grade. This is generally not an economical way to recycle plastics from household garbage since it is too costly to adequately separate and sort the different plastics and other materials which are present in household waste. Some uses are known for recycled impure waste plastics, sometimes mixed with other waste products. Typically this involves melting the plastics and pouring the melted plastics into molds to form products such as paving tiles or picnic tables. The process of pouring a mold and allowing the plastic to cure and cool, and then removing the product from the mold is a lengthy process which adds considerably to the cost of the end product and reduces its economic efficiency. 
     A method of continuously producing an elongated beam from recycled plastic material is disclosed in U.S. Pat. No. 5,413,745, issued to Curt Andersson, in which a mixture of inexpensive waste plastic and dried and heated waste fiber material such as paper is melted and compressed in a machine, and extruded in the form of a beam. The waste plastic material and the waste fiber material are preferably previously shredded or chopped up prior to feeding the same to the machine. In the Andersson process, a mixture of shredded plastic and filler material is fed by a screw feeder to a compression area where a screw conveyor of decreasing pitch further compresses the material, so that it is heated and melted. The molten mixture is continuously forced out of a square or rectangular nozzle in the form of a beam, after which moveable wall sections of a matrix are used to keep the beam shape of the material until it cools. According to Andersson, the beam of material coming out of the nozzle has a low mechanical strength, and the matrix is designed to work and cool the beam to improve its mechanical strength. The Andersson method is suitable for producing continuous elongated beams but the beams are still lacking the rigidity and strength required for structural purposes. 
     Canadian Patent No. 2,119,512, issued to Roman Evancic, provides a method and apparatus for producing shaped articles from recycled materials. The method comprises: producing a mixture of plastic and fibrous materials wherein the proportion of plastic to the fibrous materials is greater than approximately 10% and less than 60%; heating the mixture to a softened state adapted for extrusion; extruding the materials from an extrusion device through a shaping means to produce a sheet of softened extruded material; cooling and compressing the surface of the sheet to form a skin of relatively harder material on the surface of the extruded material; applying rollers having a low co-efficient of friction to the surface of the sheet under pressure to apply the desired shape to the surface of the sheet; and further cooling the sheet by the application of a cooling liquid. 
     Other patents of interest are U.S. Pat. No. 5,786,000, issued to Rolf Berner and U.S. Pat. No. 5,788,901, issued to Barnard et al. 
     SUMMARY OF THE INVENTION 
     The Andersson patent referred to above already recognizes that the beam of material coming out of the nozzle of the mixer/extruder has a low mechanical strength. To that end Andersson provides a single matrix having moveable walls adapted to contact the surface of the beam. However, the product produced by the Andersson method still has a low mechanical strength. Accordingly, the present invention provides two matrices which are separated from each other and which are positioned downstream of the nozzle of the mixer/extruder. In the present invention, the first matrix is four feet long, for example, and is provided with a plurality of moveable walls which contact and massage the outer surface of the beam as it passes from the nozzle through the first matrix. When the beam of material coming from the mixer/extruder is generally rectangular in cross section, subject to certain deviations in the upper and lower surfaces, the moveable walls can be four in number, and each wall is reciprocated by a separate piston/cylinder combination. 
     When the beam of material coming form the mixer/extruder is cylindrical in shape, the number of moveable walls can be three, for example, with each moveable wall subtending an arc of approximately 120 degrees; these walls will still be reciprocated by piston/cylinder combinations. In accordance with the present invention, the beam of material coming out of the first matrix referred to above, will pass through a second matrix which is located downstream of the first matrix and spaced therefrom. The second matrix, for example, need only be approximately two feet in length, it being understood that dimensions and shapes indicated herein are for purely illustrative purposes and not intended to be limiting. The second matrix is also provided with four moveable walls which reciprocate horizontally and whose combined inner surface corresponds with the shape of the beam of material passing therethrough. Each of the walls in the second matrix is designed to reciprocate horizontally by virtue of piston/cylinder combinations mounted on the second matrix. Preferably, the piston/cylinder combinations of the first matrix are coordinated with the piston/cylinder combinations of the second matrix such that the moveable walls of the first and second matrices are moved in concert. 
     Another feature of the present invention involves the use of cooling passageways in the moveable walls of the second matrix. Horizontal ports are provided in each of the moveable walls of the second matrix so that cooling water can flow into one passageway and out the other passageway to cool each of the walls of the second matrix. In this manner, the material passing through the second matrix will be cooled faster than the beam would otherwise be cooled by normal convection. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a semi-diagrammatic side elevation of the major components of the present invention in combination with a conventional mixer/extruder for use in producing a beam having a generally rectangular cross section. 
     FIG. 2 is a view similar to FIG. 1, but showing the major components of the present invention in association with a mixer/extruder where the end product is of cylindrical shape. 
     FIG. 3 is an end view looking along line  3 — 3  of FIG.  1 . 
     FIG. 4 is an end view looking alone line  4 — 4  of FIG.  1 . 
     FIG. 5 is an end view looking alone line  5 — 5  of FIG.  2 . 
     FIG. 6 is an end view looking along line  6 — 6  of FIG.  2 . 
     FIG. 7 is a perspective view of an end portion of one of the major components shown in FIG.  1  and showing the four moveable wall parts in horizontal alignment with each other. 
     FIG. 8 is a perspective view somewhat similar to FIG. 7 but showing the top and rear wall members moved relatively toward the mixer/extruder as compared to the front and bottom wall members. 
     FIG. 9 is a view similar to FIG. 7 but showing the bottom and rear wall members moved relatively closer to the mixer/extruder than the front and bottom wall members. 
     FIG. 10 is a view similar to FIG. 7 but showing the top and front wall members moved relatively closer to the mixer/extruder than the rear and bottom wall members. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in detail, FIG. 1 shows the major components of the present invention in association with a conventional mixer/extruder  10  essentially identical to that shown in FIG. 1 of Andersson U.S. Pat. No. 5,413,745 or FIG. 1 of Evancic Canadian Patent No. 2,119,512 dated Sep. 20, 1995. The operation of the mixer/extruder  10  is fully set forth in the disclosures of the aforementioned U.S. and Canadian Patents, the disclosures of which are incorporated herein by reference. Briefly, the mixer/extruder  10  will be provided with a nozzle (outlet) 12  having an orifice shaped to correspond with the product to be produced. In the case of FIG. 2 the orifice  12  would have a round opening. In the case of FIG. 1 the orifice  12  would have a generally rectangular opening with a ridge at the top and a notch at the bottom. 
     In FIG. 1, an extruder tube  14  is placed over the orifice  12 . The extruder tube  14  is approximately twelve inches in length as compared to the four inch high product  16  which comes out of the extruder tube  14 . The extruder tube  14  is also hollow and shaped to correspond with the outlet shape of the orifice  12  in FIG.  1  and is approximately ⅜ inch thick. 
     In relation to FIG. 2, there is an extruder tube  18  which is about eighteen inches in length and which has a circular opening corresponding with the circular opening in the orifice  12 . This arrangement provides a round beam  20  approximately four inches in diameter. The extruder tube  18  is hollow and approximately ⅜ of an inch in wall thickness as is the case with the extruder tube  14 . The extruder tube  18 , as indicated above, has a round cross section corresponding with the round opening in the nozzle  12  of FIG.  2 . 
     Andersson U.S. Pat. No. 5,413,745 is provided with a single matrix shown in FIG. 2 thereof. On the other hand, FIG. 1 of the present invention provides two matrices  22  and  24 . Everything to the left of the mixer/extruder  10  will be considered downstream. The matrix  22  is downstream of the mixer/extruder  10  and the matrix  24  is downstream of the matrix  22 . The matrix  22  would be approximately four feet in length whereas the matrix  24  would be approximately two feet in length. There is approximately a four foot separation between the two matrices  22  and  24 . The shapes of the openings provided through the matrices  22  and  24 , as will be described hereinafter in further detail, is the same shape as that of the extruder tube  14 ; i.e. substantially rectangular with a V-shaped ridge at the top and a V-shaped notch at the bottom. 
     Turning now to FIG. 2, the arrangement shown here provides a matrix  26  downstream from the mixer/extruder  10  and a second matrix  28  downstream of the matrix  26 . As in the case of FIG. 1, the matrix  26  is approximately four feet in horizontal length, the matrix  28  is approximately two feet in horizontal length and there is approximately a four foot horizontal separation between the two matrices. Again, the matrices  26  and  28  are internally shaped, as will be explained hereinafter, so that the beam  20  moving therethrough will move through a circular opening which conforms with the shape of the beam. 
     Referring now to FIG. 3, the matrix  22  consists of an external support  30  and four slidable walls  32 ,  34 ,  36  and  38 . The slidable wall  32  will be considered the upper wall and it is provided with a V-shaped notch  40  at the bottom thereof. The wall  36  will be considered as the bottom wall and it is provided with a V-shaped ridge  42  which together with the V-shaped notch on the upper slidable wall  32  engage the beam  16  along the upper and lower edges, respectively, to hold it in position while the beam is sliding through the matrix  22 . The wall  34  is a vertical side wall which is also horizontally slidable and which engages one of the vertical side edges of the beam  16 . The side wall  38  is the remaining wall which is also a vertical wall and which engages the opposite vertical side edge of the beam  16  as related to the vertical side wall  34 . 
     As best shown in FIG. 7, the upper side wall  32  is in alignment with the lower side wall  36 , whereas the side wall  34  is in alignment with the side wall  38  and all of the walls are in essentially vertical alignment at the forward end of the matrix  22 . 
     Turning now to FIG. 8, the moveable wall members of the matrix  22  have moved from the condition shown in FIG.  7 . That is, the lower wall member  36  is now downstream with respect to the upper wall member  32  and the wall member  38  is relatively downstream with respect to the wall member  34 . 
     As best shown in FIG. 9 the upper wall member  32  is provided with a pair of side extensions  44  and  46 , whereas the lower wall  36  is provided with a pair of extensions  48  and  50 . The extensions  46  and  50 , for example, provide tracks along which the side wall  38  can slide. Likewise, the extensions  44  and  48  provide tracks along which the other side wall  34  can slide. The individual wall members  32 ,  34 ,  36 , and  38  are horizontally slidable by virtue of four pistons and four cooperating cylinders (not shown) in a manner later to be described in relation to FIGS. 2 and 6. In the position shown in FIG. 9, the side wall  34  is moved in a upstream direction (towards the mixer/extruder  10 )as is also the lower wall  36 . On the other hand, the top wall  32  and the opposite side wall  38  are moved relatively farther away (downstream) from the mixer/extruder  10  as compared to their opposite wall members. 
     In the position shown in FIG. 10, the upper wall  32  is moved relatively downstream with respect to the lower wall  36  (which is not visible in this Figure) while the side wall  38  is moved relatively downstream with respect to the opposite side wall  34 . 
     Turning now to FIG. 4, this represents a view taken at the right-hand end of the downstream (shorter) matrix  24  shown in FIG.  1 . This matrix  24  is very similar to the matrix  22  but differs in two respects. First of all, it is only two feet in horizontal length whereas the matrix  22  is four feet in length. Secondly, the moveable walls, later to be described, are provided with coolant in a manner later to be described. The matrix  24  is provided with a housing  52  in which the four slidable walls of the matrix  24  are slidably received; That is the matrix  24  includes an upper slidable wall  54 , a lower opposite slidable wall  58 , a right-hand or rear (with respect to FIG. 2) wall  56 , and an opposite (front) wall  60 . These walls are similar to the walls  32  thru  38  previously described in relation to FIGS. 1,  3 , and  7  thru  10 . These walls  54  thru  60  are movable in exactly the same fashion as walls  32  thru  38 , as specifically shown in FIGS. 7 through 10, by virtue of a piston and cylinder combination, later to be described in connection with FIGS. 2 and  6 . 
     Furthermore, the pistons (not shown here) which move the moveable walls in FIG. 3 are keyed in such a way that the corresponding walls move in like fashion such that the movements shown in FIGS. 7 thru  10  in relation to FIG. 3 would be duplicated by corresponding movement of the walls in FIG.  4 . Thus, when upper wall  32  of the matrix  22  moves in an upstream direction, so also would the upper wall  54  of the matrix  24 . Likewise, when the rear side wall  34  moves in an upstream direction, so also would the rear side wall  56  of matrix  24 . Completing the comparison, side wall  38  would move in the same direction and the same amount as side wall  60  and lower wall  36  would move the same amount and direction as the side wall  58 . 
     Turning again to FIG. 4, each of the movable walls  54  thru  60  is provided with an internal passage way through which cooling water may flow, so as to cool the beam  16  as it passed through the matrix  24 . To this end, the upper movable wall  54  is provided with a pair of horizontal ports  62  and  64  which extend for the full horizontal length of the upper wall  54  and which connect at their opposite ends (in a manner not shown) so as to provide a through passage way through the movable wall  54 . A pair of hoses  66  and  68  connect with the horizontal ports  62  and  64  through suitable fittings, such that water can flow through the combined passageway  62 / 64 . Thus, if hose  66  was connected to a supply of cold water (or other suitable coolant) and hose  68  was connected to a discharge location, then water would flow through the hose  66 , into the horizontal port  62 , out the horizontal port  64  and out through the hose  68 . 
     In like manner, the rear side wall  56  is provided with horizontal ports  70  and  72  which connect with hoses  74  and  78 . Thus, cold water can pass into the hose  74 , for example, through the horizontal port  70 , back through the horizontal port  72 , and out the discharge hose  78 . 
     The lower slidable wall  58  is provided with ports  80  and  82  which connect with hoses  84  and  88  so as to provide a passage for coolant similar to the description in relation to the movable walls  54  and  56 . 
     Finally, movable wall  60  is provided with horizontal ports  90  and  92  which connect with hoses  94  and  98  to provided a flow passage for coolant through the movable wall  60 . 
     Referring now to FIG. 5, this figure shows some of the details of the upstream matrix  26  (the one which is closer to the mixer/extruder  10 ). This matrix comprises a housing  100  in which is slidably mounted an upper arcuate slidable member  102 , a right-hand (as it appears in FIG. 5) arcuate slidable member  104 , and a left-hand arcuate slidable member  106 . The slidable member  102  has an inner arcuate surface  108  which corresponds with the outer shape of the circular beam  20  as it proceeds from the extruder tube  18 . Similarly, the slidable member  108  has an inner arcuate surface  110 , and the slidable member  106  has an inner arcuate surface  112 . When the slidable members are juxtaposed as shown in FIG. 5, together they form a circular passageway in which the beam  20  is received and guided as it passes through the matrix  26 . Each one of the slidable members  102 ,  104  or  106  is individually movable or slidable in a horizontal direction by means of a plurality of pistons and cooperating cylinders as referred to above, (not shown herein) but which will be described below in relation to the description of FIGS. 2 and 6. 
     Referring now to FIGS. 2, and  6 , these figures relate to the downstream matrix  28  which is used to shape and guide the cylindrical beam  20  therethrough. The matrix  28  is provided with a frame  114  in which four slidable member are slidably received. These four members comprise an upper slidable member  116 , a right-hand slidable side member  118 , a lower slidable member  120  and a left-hand slidable member  122 . The upper slidable member  116  has an inner cylindrical surface  124  which comprises an arc of about 90 degrees. Each of the other slidable members  118 ,  120 , and  122  also has an arcuate inner surface  124  each one of which constitutes one quarter of the total cylindrical surface in which the beam  20  is received and through which the beam  20  passes. As was the case with the matrix  22 , each one of the slidable members  116 ,  118 ,  120  or  122  of the matrix  28  is individually slidable and is capable of achieving the relative positions shown in FIGS. 7 thru  10 , inclusive. 
     Each slide member shown in FIGS. 2 and 6 has a piston and cylinder associated therewith for the purpose of providing the sliding movement referred to herein. For example, slide member  116  is provided with a cylinder  126  in which is slidably received a piston  128 . The end of each piston rod  128  is enlarged, as at  130 , and is received between a pair of ears  132  mounted at the top of the upper slidable member  124 . A pin  134  passes through the ears  132  and the end  130  of the piston rod  128  so that the piston rod is in engagement with the upper slide member  116 . 
     A hose  136  connects with one end of the cylinder  126 . A second hose  138  connects with the opposite end of the cylinder  126 . If hydraulic pressure is applied to the hose  136 , the piston  128  and, hence, the slide  116  will move in a downstream direction. If, on the other hand, pressure is applied through the hose  138 , the piston  128  and the slide  116  will move in an upstream direction. Each of the other slide members  118 ,  120 , and  122  is similarly provided with cylinders  126  and pistons  128  which operate to reciprocate these members in the same way that slidable member  116  is moved back and forth in a horizontal path by its piston and cylinder combination  126 / 128 . Each cylinder  126  is associated with a piston  128  which is connected to ears  130  and  132  on each slidable member ( 118 ,  120 , or  122 ) by means of a pin  134 . Each cylinder  126  is also provided with a hose  136  which connects with one end of the cylinder  126  and a hose  138  which connects with the opposite end of the cylinder. Each cylinder  126  is operated independently of the others so that, ultimately, the type of motion of the individual slide members  116 ,  118 ,  120 , and  122  will be similar to that shown in FIGS. 7 through 10, inclusive. 
     It should be understood that the slidable members  102 ,  104 , and  106  shown in FIG. 5 are provided with pistons and cylinders (not shown) which will provide sliding movement of these members in a manner similar to that described in relation to FIGS. 2 and 6. Furthermore, upper slidable member  102  in FIG. 5 will be synchronized with the movement of the upper slidable member  116  in the matrix  28 . The right slidable member  104  will be synchronized with the movement of the right-hand slidable member  118  and the left slidable member  106  shown in FIG. 5 will be synchronized with the movement of the left-hand slidable member  122  shown in FIG.  6 . There will be no member in the matrix  26  which will be coordinated with the movement of the lower slidable member  120  in FIG.  6 . 
     For the sake of simplicity, the drawings do not show that the matrices  22  and  24  are provided with pistons and cylinders, such as the piston/cylinder combination  126 / 128 , associated therewith. However, it should be understood that similar cylinders and pistons,  126  and  128 , will be actually associated with the slidable members in these matrices; for the sake of simplicity, however, they are not illustrated nor will the descriptions thereof be repeated. 
     Whereas the present invention has been described with particular relation to the drawings attached hereto, it should be understood that other and further modifications of the present invention, apart from those shown or suggested herein, may be made in the spirit and scope of this invention. It should be further understood that sizes and dimensions, where given, are merely illustrative and are not intended to be limiting on the invention. The Andersson patent and the Evancic patent, discussed above, describe in general terms the proportions of ingredients that can be used in the mixer/extruder for producing the beam desired. It should be understood that the choice of the actual proportions can be made by the man skilled in this art depending, principally upon the properties of the ultimate product desired.