Abstract:
A method and apparatus for manufacturing a flexible curtain is disclosed and claimed. The flexible curtain is used in a windlocking apparatus to prevent the unwanted intrusion of wind, water and debris into a building opening. Strips are attached to the edges of the curtain. The strips may be attached to the curtain by first heating them followed by compressing them to form a welded or bonded construction. The heating may be accomplished by direct heat transfer, electromagnetic excitation, or ultrasonic excitation. Compressing the materials together is accomplished with rollers having cylindrical laminating surfaces to join the excited materials and form a welded or bonded construction. Alternatively, the materials may be glued or stitched together. Preferably the curtain and strips are thermoplastic materials. Semi-crystalline polymer strips may be joined to a thermoplastic curtain to add rigidity.

Description:
[0001]    This is a continuation-in-part patent application of co-pending patent application Ser. No. 09/644,926, filed Aug. 23, 2000. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention is a method and apparatus for making a flexible curtain for use as a windlocking curtain.  
         BACKGROUND OF THE INVENTION  
         [0003]    During hurricanes and other high wind velocity storms, the breach of a building opening can cause great damage to the structure. We have U.S. Pat. No. 6,296,039 B1 which addresses the use of the windlocking curtain in storm conditions. This invention discloses and claims the method and apparatus for making the windlocking curtain.  
         SUMMARY OF THE INVENTION  
         [0004]    A method for manufacturing a three-ply flexible curtain is disclosed. Two of the plys are polymeric and one is a woven substrate which resides between the two polymeric plies. A first and second laminating roll under the force of pressure and heat secures the three plys together. A plurality of beveled rollers fold the edges of the three ply construction back upon itself.  
           [0005]    A first and second edge roller are used to laminate the folded edge to itself. The second edge roller has a notch which limits the extent of the lamination because the notched area on the second edge roller does not allow compression of the folded edge. Lack of compression of the folded edge in the notched area results in a loose flap which is useful in the application of the flexible curtain for absorbing shock during transient (storm) conditions. Alternatively, and/or additionally, the secured portion of the folded edge may be glued, stitched or welded. Perforations are made in the folded edges of the curtain. Rotary, stationary or indexing punches and dies may be used.  
           [0006]    Alternatively, a curtain made from a single substrate may be manufactured. This curtain has two edges and each of the edges in turn has a strip affixed to it. The strips may be partially affixed to the curtain or they may be substantially entirely affixed to the curtain. The strips affixed along the edges of the curtain are necessary in the functioning as set forth in U.S. Pat. No. 6,296,039 B1. The strips may be affixed by laminating them under pressure to the curtain, gluing them to the curtain, stitching them to the curtain, or by welding them to the curtain using microwave welding devices, ultrasonic welding devices, radio frequency welding devices, heat welding devices and induction welding devices. Appropriate combinations of the preceding methods of attachment may be used if redundant securement is desired or if incompatible materials are used.  
           [0007]    The curtain can be made from any polymeric material and, preferably, a thermoplastic material to facilitate welding. The strips which are affixed to the edges of the curtain can be made from any polymeric material and, preferably, a thermoplastic material to facilitate welding. Alternatively, the strips may be made from a semi-rigid material such as a semi-crystalline polymeric material.  
           [0008]    It is an object of this invention to produce a flexible curtain having a folded edge which is partially secured to itself and which is partially unsecured.  
           [0009]    It is a further object of this invention to produce a flexible curtain having a folded edge which has perforations therethrough where the edge is partially secured to itself.  
           [0010]    It is a further object of this invention to produce a flexible curtain having a folded edge which has a loose, or free, flap capable of absorbing energy.  
           [0011]    It is a further object of this invention to use a first edge roller and a second edge roller to partially laminate the folded edges of the flexible curtain.  
           [0012]    It is a further object of this invention to fold the edges of a flexible curtain so that they may be partially laminated, glued, stitched or welded together.  
           [0013]    It is a further object of this invention to laminate two plys of polymeric material to a woven substrate residing therebetween.  
           [0014]    It is a further object of this invention to completely secure two strips of polymeric material to a polymeric substrate. Cylindrical laminating surfaces compress the entire strip and the edge of the curtain securing each to the other. The substrate itself may be a single sheet of polymeric material or it may comprise two or more polymeric sheets laminated together. Preferably the polymeric substrate is a thermoplastic material. Alternatively, and additionally, another substrate such as a woven cloth substrate or a reinforcing metal substrate may be laminated between the polymeric substrates.  
           [0015]    It is a further object of this invention to secure thermoplastic polymeric strips to a thermoplastic polymeric substrate.  
           [0016]    Other objects of this invention will become apparent when the drawing figures, the description of the invention and the claims are considered which follow hereinbelow. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a perspective view of the invention illustrating, among other things, the laminating rollers, the edge rollers, and the perforating rollers.  
         [0018]    [0018]FIG. 1A is a perspective view similar to FIG. 1 without the stitching apparatus.  
         [0019]    [0019]FIG. 1B is a partial cross-sectional view of the flexible curtain illustrating a folded edge.  
         [0020]    [0020]FIG. 2 is a view illustrating much of the same structure as FIG. 1 only supports are not shown in this view.  
         [0021]    [0021]FIG. 3 is an enlarged portion of FIG. 2.  
         [0022]    [0022]FIG. 3A is an illustration of one edge of the curtain between the first edge roller and the second edge roller. FIG. 3A also illustrates the notch in the second roller.  
         [0023]    [0023]FIG. 4 is another embodiment of the invention illustrating strips applied to the edges of the curtain.  
         [0024]    [0024]FIG. 4A is another embodiment of the invention illustrating ultrasonic welding of the strip to the edge of the curtain after compression of the strip to the curtain.  
         [0025]    [0025]FIG. 4B is another embodiment of the invention illustrating welding devices selected from the group of microwave, ultrasonic, radio frequency (RF), heat and induction welding devices. The welding devices are illustrated schematically before compression of the strips to the curtain.  
         [0026]    [0026]FIG. 4C is an enlargement of a portion of FIG. 4B illustrating welding devices selected from the group of microwave, ultrasonic, radio frequency (RF), heat and induction welding devices.  
         [0027]    [0027]FIG. 4D is a drawing similar to FIG. 4B with the curtain comprising a single substrate or sheet.  
         [0028]    [0028]FIG. 5 is an enlargement of a portion of FIG. 4A.  
         [0029]    [0029]FIG. 6 is an enlargement of a portion of FIG. 1 illustrating a rotary punch and die for perforating the folded edges of the flexible curtain.  
         [0030]    [0030]FIG. 7 is an enlargement of a portion of FIG. 6 better illustrating the perforations in the folded edges.  
         [0031]    [0031]FIG. 8 is an enlargement of a portion of FIG. 1 illustrating the stitching apparatus.  
         [0032]    [0032]FIG. 9 is a flow chart of a stationary punching system.  
         [0033]    [0033]FIG. 10 illustrates a punch and a die in cross section.  
         [0034]    [0034]FIG. 11 illustrates the punch and die of FIG. 10 in perspective.  
         [0035]    [0035]FIG. 12 is a perspective view of the punch and die shown together with the curtain.  
     
    
       [0036]    A better understanding of the invention will be had when reference is made to the description of the invention and the claims which follow hereinbelow.  
       DESCRIPTION OF THE INVENTION  
       [0037]    [0037]FIG. 1 is a perspective view of the invention illustrating, among other things, the laminating rollers  108 ,  109  the edge rollers and the perforating rollers. FIG. 1A is a perspective view similar to FIG. 1 without the stitching apparatus  120 ,  121 . The stitching apparatus  120 ,  121  shown in FIG. 1 ensures that the folded edge  132  is affixed completely to the flexible curtain  128 . Lamination alone of the edge  132  to the flexible curtain  128  is sufficient to attach the edge to the curtain. Stitching  120 ,  121 , gluing  170  or welding  405 ,  406  (see, FIG. 4A) are additional methods of ensuring that the folded edge  132  is completely affixed to the flexible curtain.  
         [0038]    Referring to FIGS. 1 and 1A, reference numeral  101  represents the frame which positions the equipment for performing the method. First roll  102  has first polymeric material  105  wound therearound. Second roll  103  has woven sheet  106  (FIG. 2) wound therearound. Third roll  104  has second polymeric material  107  wound therearound. First and second polymeric sheets  105 ,  107  are laminated to the woven sheet  106  and to each other by the first laminating roll  108  and the second laminating roll  109 . The three sheets  105 ,  106  and  107  are best viewed in FIG. 2 which is a view illustrating much of the same structure as FIG. 1 only the supporting frame  101  and structure are not shown. FIG. 2 also illustrates a slitter  180  which controls the width of the laminated curtain prior to folding of the edges.  
         [0039]    Referring to FIG. 3, which is an enlarged portion of FIG. 2, one set of beveled rollers  111  (first),  113  (second),  114  (third) and  116  (fourth) are illustrated. The other set of beveled rollers  110 ,  112 ,  115  are also viewed in FIGS. 1, 1A and  2 . There are four beveled rollers on the far side but only three are visible in these perspective views.  
         [0040]    Referring to FIGS. 2 and 3, first beveled roller  111  and second beveled roller  113  begin to turn the edge of the flexible curtain  128  vertically upward. Third beveled roller  116  in combination with second beveled roller  113  begin to fold the flexible curtain inwardly on itself Fourth beveled roller  114  completes the fold. Although the flexible curtain is folded leaving fourth beveled roller  114 , it is not laminated upon itself at this point. FIG. 1B is an illustration of the curtain and an edge  132  folded upon itself but not laminated.  
         [0041]    Folded edge  132  next passes through first edge roller  118  and second edge roller  119 . Referring to FIGS. 3 and 3A, first edge roller  118  includes an enlarged end portion  183  which is cylindrically shaped and has a constant diameter. Second edge roller  119  includes an enlarged end portion  186  which is cylindrically shaped and has a circumferential notch  185  therein. Circumferential notch  185  is a circumferential notch in cylindrical end portion  186  of edge roller  119 . As folded edge  132  passes through end portions  183  and  186  of edge rollers  118 ,  119  it is compressed and laminated except for the portion proximal (i.e., near) to notch  185 . The function of the circumferential notch  185  is to prevent lamination of the folded edge portion  132  of the flexible curtain proximal (i.e. near) the notch. Reference numeral  135  indicates the extent of the folded edge  132  which is not laminated. See, FIG. 3A.  
         [0042]    [0042]FIG. 1A represents an embodiment of the invention. Stitching apparatus  120 ,  121  may be employed to reinforce the attachment of the folded edge  132  to the flexible curtain  128 . A stitching apparatus  120  can be seen in more detail by referring to FIG. 8, an enlargement of a portion of FIG. 1. FIG. 8 illustrates thread  124 ,  125  needles  126 ,  127 , and stitching  133 ,  134 . Another method of reinforcing the bond between the folded edge  132  and the flexible curtain  128  is to apply adhesive with an applicator  170  prior to completion of the folding of the edge as best seen in FIGS. 1, 2 and  3 . Still referring to FIG. 8, reference numeral  129  indicates the area of the folded edge secured by the stitching. Referring to FIG. 1, stitching is indicated by reference numerals  129  and  130 . Stitching may be used in addition to lamination. When the flexible curtain produced by this invention is used to protect building openings, great force will be exerted on the portion of the folded edge secured to itself. Redundant securement of the folded edge can also be effected by ultrasonic welding  405 ,  406  (FIG. 4A), heat welding or electromagnetic welding (FIG. 4B).  
         [0043]    [0043]FIG. 4 is another embodiment  400  of the invention illustrating polymeric strips  403 ,  404  applied to the edges of the curtain. Polymeric strips  403 ,  404  are coiled up in coils  401 ,  402  on a spindle  420  and are dispensed therefrom and laminated by edge rollers  118 ,  119 . Additionally, the strips may be stitched with stitching apparatus  120 ,  121  (FIG. 4) or ultrasonically welded  405 ,  406  (FIG. 4A). FIG. 4A is another embodiment of the invention  400 A illustrating ultrasonic welding of the strips  403 ,  404  to the edge of the curtain  128  after compression of the strips to the curtain. FIG. 4A illustrates ultrasonic welding after lamination of the strips to the curtain. FIG. 5 is an enlargement of a portion of FIGS. 4 and 4A and better illustrates the lamination of the strips  403 ,  404  to the three ply flexible curtain  128 .  
         [0044]    Welding of polymeric material involves the heating of the materials to be joined followed by the application of pressure to the material to be joined. Depending on the type of heating source used in the welding process, the application of pressure is simultaneous or nearly simultaneous with the application of heat to the material to be joined. The variables of heating, pressure and time are to a certain extent dictated by the materials to be joined.  
         [0045]    [0045]FIG. 4B is a view similar to FIG. 4A with welding devices  431  and  434  shown schematically. Bracket  430  is illustrated supporting welding device  431 . Arrows  432  and  433  schematically indicate heating of the curtain and the strips  402  and  403  by any of the methods, namely, heating, induction, microwave, radio frequency or ultrasonic. Additionally, the strips  403 ,  404  are completely affixed to the curtain  128  as illustrated in FIG. 4B. This embodiment differs from the embodiment of FIGS. 4 and 4A wherein only portions of each of the strips  403  and  404  are affixed to the curtain leaving flaps or remainders unsecured to the edges. The embodiment of FIGS. 4 and 4A require notch  185  in roller  186 .  
         [0046]    In the embodiment of FIG. 4B, compressing or laminating surfaces  183  and  190  of rollers  118  and  119  compress the entirety of the polymeric strips to the curtain  128  shortly after the strips and curtain have been heated. Heating takes place as a result of subject the material to be heated to hot air, sonic energy or electromagnetic energy (radio frequency energy, electrical induction energy or microwave energy). Neither roller  183  nor roller  190  has a notch therein. The curtain may be a three-ply curtain  128  as is illustrated in FIG. 4B or it may be a single ply curtain  128  as indicated in FIG. 4D.  
         [0047]    The type of weld used will be determined by the type of curtain and strips used. Heat welding may be performed using various types of vinyl films, vinyl laminated fabrics, vinyl coated fabrics, propylene, polyethylene and urethane films. Thermoplastic materials have a linear macro-molecular structure that will repeatedly soften when heated and harden when cooled. Essentially, thermoplastic means becoming plastic on being heated and includes any resin which can be melted by heat and then cooled repeatedly any number of times without appreciable change in properties. Examples of thermoplastic materials are styrene, acrylics, cellulosics, polyethylenes, vinyls, nylons, and fluorocarbons. Semicrystalline plastics such as polypropylene have some thermoplastic properties but required different techniques and energy levels in the welding process.  
         [0048]    The welding devices illustrated in FIGS. 4B, 4C, and  4 D are well known for use in other arts and are shown schematically here. These welding/heating devices could also be oriented downstream of the compression rollers  183 ,  190  as illustrated in FIG. 4A but usually welding occurs nearly simultaneously with the application of pressure. These welding devices can be selected from the group of microwave, ultrasonic, radio frequency (RF), heat and induction.  
         [0049]    Devices  431  and  434  of FIG. 4B may be hot air or heat devices. Reference numerals  432  and  433  indicate arrows which in turn indicate the application of hot air to the surfaces to be joined. Heat welding, also known as rotary heat sealing, is performed by injecting hot air between two layers ( 128 ,  403 , 404 ) of thermoplastic material and preparing the two surfaces for molecular bond. The temperature used in combination with the amount of air used determines the amount of energy transferred to the thermoplastic material to be welded together. Pressure and speed are controlled by the laminating surfaces  183  and  190 . The rate of rotation of the rollers is the speed at which the material is bonded together and the pressure applied is determined by the spacing between the laminating surfaces  183  and  190 . Heat welding provides a very good bond of thermoplastic materials.  
         [0050]    Devices  431  and  434 , shown schematically in FIG. 4B, may be radio frequency devices. Radio frequency welding (RF welding) is also known as dielectric welding. Radio frequency welding is the process of fusing material together by applying radio frequency energy to the material. Radio frequency welding is used to join or assemble various thermoplastic materials such as PVC (polyvinylchloride) and polyurethanes. Unlike a straight heat weld, the material is only heated while RF energy is being generated.  
         [0051]    Radio frequency welding, or dielectric welding, uses a high frequency radio signal acting upon a polar polymer. Thermoplastic polymers are placed between electrodes which are excited by a radio frequency generator. Each of the electrodes is alternately positively and negatively charged with the frequency being switched at the rate of the generator. The thermoplastic polymers heat up from the friction between the molecules of the polymers as they are subjected to the alternating electromagnetic field. See, www.ferris.edu/cot/accounts/plastics/htdocs/Prey as published by Ferris State University, and as authored by Matt Prey, which is incorporated herein by reference.  
         [0052]    RF Welds are usually as strong as the original material prior to welding. Materials that are commonly RF welded include polyvinylchloride (PVC), ethylene vinyl acetate, polyurethanes, polyethylene terephtalate and polyamide. Some thermoplastics such as polyethylene and polypropylene cannot be welded using RF energy. The speed and pressure of the laminating surfaces  183  and  190  will be dictated by the material used and the amount of radio frequency energy inputted into the flexible curtain  128  and the polymeric strip  403 ,  404 .  
         [0053]    Usually, RF energy is directed toward the materials to be joined while they are in direct contact with each other. Referring to FIG. 4B, a certain liberty has been taken with respect to the depiction of RF sources  431  and  434  in that they indicate application of radio frequency energy into the curtain and the polymeric strip  403 ,  404  while the two are separated and just before they join under the influence of laminating surfaces  183  and  190 . Further, it will be understood by those skilled in the art that the illustration of the radio frequency sources is a schematic and that radio frequency welding equipment well known in the art can be spatially adapted to the process illustrated in FIG. 4B. Also see, http://www.ewi.org/technologies/plastics/dielectric.asp which is incorporated herein by reference.  
         [0054]    Devices  431  and  434 , shown schematically in FIG. 4B, may be ultrasonic welding devices. Ultrasonic welding of plastics is a technology which has been practiced for several years. Vibrations are introduced vertically and frictional heat is produced so that the material plasticizes and connects very quickly. The materials to be joined must have similar melting points.  
         [0055]    A metal tool (horn) oscillates vertically and transforms electrical energy into sound energy. The frequency of oscillations usually varies between 20 to 40 kHz but the frequency may be outside that range. Oscillation amplitudes range from 20 to 80 microns.  
         [0056]    Ultrasonic welding is used to join amorphous (i.e., non crystalline) thermoplastics. However, semicrystalline polymers are welded routinely now using high power machines. Many variables are microprocessor controlled during ultrasonic welding. See, www.ewi.org/technologies/plastics/ultrasonic.asp which is incorporated herein by reference.  
         [0057]    Devices  431  and  434 , shown schematically in FIG. 4B, may be microwave devices. Microwave welding is similar to radio frequency welding, except that it uses a much higher frequency from 70 MHz to 100 GHz. A composite gasket is used which is a combination of a thermoplastic parent material and a conductive material, known as an electromagnetic susceptor. Polyaniline, or PANI is an organic metal which may be used as the conductive material in the gasket. Polyaniline is sometimes referred to as a polyaniline salt. See, www.ferris.edu/cot/accounts/plastics/htdocs/Prey as published by Ferris State University, and as authored by Matt Prey which is incorporated herein by reference. Polyaniline is sometimes referred to as a polyaniline salt.  
         [0058]    Polymers that conduct electric currents without the addition of conductive (inorganic) substances are known as intrinsically conductive polymers are these materials conduct electric currents without the addition of inorganic substances (i.e., metals).  
         [0059]    Polyaniline (PANI) has achieved wide spread commercial availability. See, www.zipperling.de which is incorporated herein by reference in regard to polyaniline. Polyaniline is produced by Zipperling Kessler &amp; Co. located in Ahrensburg, Germany.  
         [0060]    The electromagnetic susceptor in the gasket absorbs the microwave energy and heats up. Thermoplastic substances that are to be welded together heat up as heat generated from the gasket is transferred to the thermoplastic material creating a molten layer which allows the molecules to inter-diffuse. The susceptor is placed between the substrates and as the susceptor is heated, that heat is transferred to the substrates forming a molten layer on each of the substrates. Pressure is then applied to the substrates which extracts the susceptor and welds the thermoplastic substrates together. Referring to FIG. 4B, a susceptor is placed between the strips  403 ,  404  and the curtain  128 .  
         [0061]    Devices  431  and  434 , shown schematically in FIG. 4B, may be induction heating devices. Induction welding magnetically excites a ferromagnetic material located within the thermoplastic material to be joined. The ferromagnetic material heats up because it is magnetically coupled to the exciter coil and the heat is transferred to the thermoplastic material around it. Inductive heating works on the same general principle as a transformer or electric motor. An external force or pressure is then applied, for instance, by laminating surfaces  183 ,  190  forcing the molten material to flow and weld the thermoplastic materials. See, http://www.ewi.org/technologies/plastics/induction.asp which is incorporated herein by reference. Thermoplastics are readily weldable by the induction welding process.  
         [0062]    [0062]FIG. 4C is an enlargement of a portion of FIG. 4B illustrating welding devices selected from the group of microwave, ultrasonic, radio frequency (RF), heat and induction welding devices. FIG. 4C illustrates the arrows  432  and  433  which schematically depict the heating of the curtain and the strip  404  by different heating devices.  
         [0063]    [0063]FIG. 4D is a drawing similar to FIG. 4B with the curtain comprising a single substrate or sheet  128 .  
         [0064]    [0064]FIG. 6 is an enlargement of a portion of FIG. 1 and illustrates the first perforating rollers  122 ,  123  with protrusions  140  therein. The rotary punch and die are usable on the curtains having folded edges and they are useful on the curtains which have a polymeric strip secured thereto as set forth in FIGS. 4, 4A,  4 B,  4 C and  4 D. Sometimes herein the perforating rollers  122 ,  123  are referred to as rotary punches. Reciprocating rollers  144 ,  145  have apertures or dies  142  therein which receive the protrusions  140  together with the polymeric material which has been punched out. Protrusions  140  and dies  142  are preferably cylindrical but other shapes may be used. By punched out it is meant perforated as indicated by the perforations  141  in FIG. 7. FIG. 7 is an enlargement of a portion of FIG. 6. The punched out material exits the die through passageways (not shown in the drawings). The rotary dies can be driven by a motor if desired.  
         [0065]    Alternatively, the flexible curtain may be driven by a motor  906  and may include a capacitance station  905  if stationary punching is desired. See, FIG. 9, an embodiment of the invention set out in diagrammatic form and represented generally by the reference numeral  900 . This embodiment discloses a drive system and a stationary punch. A three ply polymeric flexible curtain is laminated initially in the first step  901 . Edges are folded and adhesive is applied in the next step  902 . Those edges are laminated  903  and additionally may be stitched  904 . A capacitance station  905 , sometimes referred to herein as a surge station, may be used if a stationary punch is employed. A first periodic motor and drive  906  feeds the stationary punch  907 . A second periodic motor and drive  908  is synchronized to the first periodic motor and drive  906  and feeds a cutter  909  which cuts the flexible curtain into usable lengths.  
         [0066]    The stationary punch  1000  is illustrated in FIGS. 10 and 11. FIG. 10 is a cross sectional view illustrating the die  1004  and the punch  1003  having projections  1001 . Apertures  1002  accept the projections  1001  and may be of varied sizes and shapes. Punched out material exits the die  1004  at the bottom of the apertures  1002 .  
         [0067]    Reference numeral  1200  illustrates the punches  1003  and the dies  1004  in position. The punches and dies may be indexed as indicated by the letter T which stands for translational movement of the dies at the same speed of the curtain. Operator  1201  represents diagrammatically the structure necessary to drive the punch  1003  into the die  1004 .  
         [0068]    It will be apparent to those skilled in the art that several changes may be made to the invention as disclosed herein without departing from the spirit and the scope of the appended claims.