Abstract:
A louver blade comprises an elongated body made of extruded plastic having first and second plastic strips disposed within and off-center from the longitudinal axis of the body. A method for making a louver blade comprises extruding plastic in a shape of a louver blade into a die; feeding first and second plastic strips through a cavity of the die; cooling the extruded louver blade; and cutting the extruded louver blade into desired length.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a louver blade used for shutters for windows, doors or similar architectural openings and in particular to a reinforced louver blade made from plastic materials. 
       BACKGROUND OF THE INVENTION 
       [0002]    Typical louver blades are used in making shutters, where the blades are either fixed or movable. In each case, the blades are supported only at either end. In a movable shutter, pins are provided at either end along the longitudinal axis to allow pivoting. Prior art louver blades made from plastic materials have limited span lengths. When used for wider openings, these louver blades tend to sag, making them less desirable. There is, therefore, a need for a plastic louver blade that is more rigid and thus able to span a wider distance without noticeable sagging. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0003]    It is an object of the present invention to provide a reinforced plastic louver blade with greater rigidity than non-reinforced louver blades, thereby allowing for wider spans without noticeable sagging. 
         [0004]    It is another object of the present invention to provide a reinforced plastic louver blade that can be extruded in a continuous process. 
         [0005]    In summary, the present invention provides a louver blade, comprising an elongated body made of extruded plastic having first and second plastic strips disposed within and off-center from the longitudinal axis of the body. 
         [0006]    The present invention also provides a method for making a louver blade, comprising: extruding plastic in a shape of a louver blade into a die; feeding first and second plastic strips through a cavity of the die; cooling the extruded louver blade; and cutting the extruded louver blade into desired length. 
         [0007]    These and other objects of the present invention will become apparent from the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a fragmentary, perspective view of louver blade made in accordance with the present invention, with portions shown in cross-section. 
           [0009]      FIG. 2  is a schematic diagram of an extrusion process used in making the louver blade of  FIG. 1 . 
           [0010]      FIG. 3  is a schematic side elevational view of  FIG. 2 , with portions shown in cross-section. 
           [0011]      FIG. 4  is a perspective view of a die used in the present invention, showing entry slots for the reinforcement strips. 
           [0012]      FIG. 5  is a cross-sectional view taken along line  5 - 5  of  FIG. 4 , showing the internal passageways for the hot plastic melt. 
           [0013]      FIG. 6  is a cross-sectional view taken along line  6 - 6  of  FIG. 5 . 
           [0014]      FIG. 7  is the same view as  FIG. 6 , showing the reinforcement strips and the hot plastic melt filling up the internal passageways. 
           [0015]      FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 5 . 
           [0016]      FIG. 9  is the same view as  FIG. 8 , showing the passageways filled with hot plastic melt and the reinforcement strips supported within the die. 
           [0017]      FIG. 10  is a cross-sectional view taken along line  10 - 10  of  FIG. 5 . 
           [0018]      FIG. 11  is the same view as  FIG. 10 , showing the hot plastic melt filling up the die cavity and enclosing the reinforcement strips. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    A louver blade  2  made in accordance with the present invention is disclosed in  FIG. 1 . The louver blade  2  is an elongated body made of extruded plastic material, such as cellular PVC. A hard skin  4 , shown in dashed lines, is preferably formed around the body by rapid cooling of the profile during the extrusion process. Longitudinal reinforcement plastic strips  8  and  9  made of glass fibers in a PVC resin are fed into the extrusion die thereby to be embedded within the body of the blade  2  during the extrusion process. 
         [0020]    The louver blade  2  is preferably oblong in cross-section, having a longitudinal axis  10 . Other profile shapes may be used. The louver blade  2  may have a horizontal plane of symmetry containing the axis  10 . The louver blade  2  in cross-section has thicker middle portion  12  and thinner end portions  14 . The fiberglass-reinforced strips  8  and  9  are preferably disposed in the middle portion  12  offset from each other horizontally and vertically, such that both strips are vertically and horizontally apart from each other. The upper strip  8  is disposed closer to a top surface of the louver blade  2 , while the lower strip  9  is disposed nearer to a bottom surface of the blade. The upper strip  8  is offset towards to the left, while the lower strip  9  is offset towards the right. The strips in cross-section said first and second strips in cross-section have wider than taller dimensions and the wider dimensions are disposed horizontally within the body of the louver blade. 
         [0021]    The strips are advantageously packaged in a spool in lengths of 1,500 feet or more, thereby providing for continuous extrusion process without interruption, except for replacing a spent spool. The strips  8  and  9  advantageously provide reinforcement and rigidity to louver blade  2 , which is typically supported at opposite ends with pins, as for example in a shutter application. With the inclusion of the fiberglass strips  8  and  9 , the typical span is substantially increased from about 20-22 inches to about 28-30 inches without noticeable sagging. The strips  8  and  9  advantageously counteract each other to provide rigidity. When the louver blade  2  is hung, the top fiberglass strip  8  will be under compression while the bottom fiberglass strip  9  will be under tension. The compressive and tensile forces thus generated in the strips would tend to counteract each other, thereby providing a more rigid louver blade. The strips are available from Strongwell, Bristol, Va. 
         [0022]    Referring to  FIG. 2 , an extrusion system used in making the louver blade  2  is disclosed. The system includes an extruder  18  extruding foam or cellular PVC plastic into a die  20 . A spool  22  carries the glass fiber reinforcement strips, which are fed into an embosser  24  that roughens the top and bottom surfaces of the strips before they are fed into the die  20 . The die  20  provides the desired shape to the louver blade  2 . 
         [0023]    A shaper  26  cools the hot, extruded plastic and provides a hard skin around the body of the blade. The shaper  26  includes a passageway made in the same cross-sectional shape as the die. The shaper  26  is immediately next to the cavity of the die in which the hot extruded plastic takes its profile. The shaper  26  includes cooling passageways through which chilled water is circulated, thereby cooling the outer surface of the hot extruded plastic to form the hard skin  4  as it passes through the chilled shaper. 
         [0024]    The extruded louver blade then passes to a sizer  28  where further cooling is accomplished. The sizer  28  has a passageway in the same shape and size as the cross-sectional shape of the blade  2 . The sizer  28  is immersed in chilled water inside a cooling tank  30 , which is kept at a vacuum to keep the shape of extruded plastic profile and keep it from collapsing onto itself as it cools down. 
         [0025]    The extruded blade emerges from the cooling tank  30  into a puller  32 , which pulls the extruded blade through the extrusion system. A saw  34  cuts the extruded blade into the desired length pieces, as generally shown at  36 . With the use of longer length strips, there is assurance that the reinforcement strips will be continuous in each cut length. 
         [0026]    Referring to  FIG. 3 , the strip embosser  24  includes upper and lower rolls  38  that provide an embossed pattern on the upper and lower surfaces of the strips  8  and  9 . The pattern provides a rough texture, such as a cross-hatching pattern, on the surfaces of the strips onto which the extruded plastic can attach itself. The rolls  38  initially drive the strips  8  and  9  into the die  20 . Once the hot plastic is pushed into the die  20  the forces of the moving molten plastic pulls the strips along. 
         [0027]    The shaper  26  has an inlet  40  for chilled water to cool the outer surface of the extruded plastic to provide the hard skin  4  around the body of the louver blade. An outlet  42  draws the chilled water back to the chiller (not shown). 
         [0028]    From the shaper  26 , the extruded plastic passes through the sizer  28 , which has the same cross-sectional cavity shape as the shaper  26  in the die  20 . The sizer  28  is submerged in chilled water inside the cooling tank  30 . The chilled water circulates through inlet  44  and outlet  46  through a chiller (not shown). The chilled water temperature is approximately 55°-60° F. The tank  30  is maintained in a vacuum, preferably ranging from 1-5 inches of mercury. An outlet  47  is connected to a vacuum pump (not shown). The vacuum advantageously keeps the hot extruded plastic from collapsing at it cools. The sizer  28  thus keeps the shape of the extrusion at it continues to cool down. 
         [0029]    The extruded plastic blade  2 , after exiting the cooling tank  30 , is gripped between upper and lower endless tracks  48  that pull the extruded plastic blade along the extrusion system. The tracks are equipped with rubber treads adapted to grip the plastic blade. The cutter  34  cuts the extruded blade into the desired lengths. 
         [0030]    Referring to  FIG. 4 , the die  20  includes upper and lower slots  50  and  52  through which the strips  8  and  9  are inserted. The slots  50  and  52  are entry ways into passageways  54  and  56  that guide the strips through the die  20 . It will be seen that the passageways  54  and  56  maintain the placement of the strips in relation to the body of the louver blade. The passageways end at the entrance to a die cavity  58  which has the desired cross-sectional or profile shape for the louver blade  2  to be extruded. The hot molten plastic is fed from the extruder  18  through an oblong, doughnut shaped, tapering passageway  60  that extends through the die and ends at the entrance to the cavity  58 . The direction of the plastic flow from the extruder  18  is transverse to the direction of flow of the plastic through the die  20  to advantageously clear the front area of the die where the strips are inserted. The passageway  60  narrows down as it approaches the entrance to the cavity  58 , as shown in  FIG. 8 .  FIGS. 7 and 9  show the passageway  60  filled with melted plastic as it flows through the passageway and into the cavity  58 . 
         [0031]    While this invention has been described as having preferred design, it is understood that it is capable of further modification, uses and/or adaptations following in general the principle of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains, and as may be applied to the essential features set forth, and fall within the scope of the invention or the limits of the appended claims.