Patent Publication Number: US-6908661-B2

Title: Cellular panel and method and apparatus for making the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a division of application Ser. No. 09/442,090 titled “CELLULAR PANEL AND METHOD AND APPARATUS FOR MAKING THE SAME” filed Nov. 11, 1999, now U.S. Pat. No. 6,284,347; which is a continuation of U.S. patent application Ser. No. 08/880,569 filed Jun. 23, 1997, now U.S. Pat. No. 6,045,890; which is a continuation of U.S. patent application Ser. No. 08/273,469 filed Jul. 11, 1994 now U.S. Pat. No. 5,888,639; which is a continuation of U.S. patent application Ser. No. 08/273,469 filed Jul. 11, 1994, abandoned, all of which are incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to cellular insulation panels. It has one of its most important applications as an insulating panel for covering windows or other openings. These panels most commonly comprise a plurality of tubular sections adhesively secured together. The panel can be oriented so that the tubular sections form a horizontally contractible and expandable panel which extends vertically, such as when covering a doorway or other similar openings. The panel more commonly is used with an orientation where the tubular sections form a vertically collapsible and expandable panel extending horizontally, such as when covering a window. 
     In window covering, the panel is mounted upon a headrail with pull cords extending down through holes in the panel to a bottom rail secured to the bottom of the panel. In some panel designs, each tubular section is a strip of usually thermoplastic woven or unwoven sheet material folded into an open-top tube. Each tube-forming strip is initially completely separate from the other tubular strips forming the panel and is laminated to the adjacent strips of the panel by bands of adhesive. The folds of each tubular section are usually sharp or set so that they appear as lines or bands which improve the aesthetic appearance of the panel. Such a panel is disclosed in Dutch Published Application No. 6706563 published Nov. 11, 1968 to Landa. In this Dutch publication, the cells have a rectangular, hexagonal or a pointed oval shape, depending on the width of the adhesive bands and the degree of expansion of the cells. If the adjacent tubular sections are secured together over wide securement bands and are fully expanded, the cells have a rectangular shape, as is shown in U.S. Pat. No. 4,019,554 granted on Apr. 26, 1977 to Rasmussen. 
     In another form of cellular panel construction, a pair of zig-zag shaped sheets of material are placed into confronting relation and secured together at the abutting fold points, to form diamond-shaped cells. This panel construction is disclosed in U.S. Pat. No. 2,201,356 granted Nov. 21, 1938 to Terrell. 
     The rear side of all these cellular panels, which interrupt the passage of light when covering a window, preferably have a color to reflect light. The front side of the panels, which face into the room involved, desirably have an appearance from a strictly aesthetic standpoint. In the panel design where each tubular section is made of a separate sheet of material folded into a tube, one half of the sheet may be printed or embossed before it is folded into a tubular shape, so that the portion of each sheet which faces the inside of the room is provided with the desired aesthetic appearance. The other half of each sheet, which faces towards the window has color to reflect light. If the initial sheet of material is already of a desired light color to reflect light, it can remain without any added coloring. If the sheet forming each tubular strip is made of an expensive material to give the front side of the panel an attractive appearance, the high cost of the portion of the same sheet which is to face the window is an undesired expense. 
     The panel design having diamond shaped cells, described previously, made from a pair of separate, confronting zig-zag shaped sheets does not have this problem as only the front sheet must be made of the more expensive material. However, this type of panel is less attractive to some purchasers than the panel having pointed oval, hexagonal or rectangular cells. Also, the method required for fabricating the panel made from zig-zag shaped sheets is less efficient and more difficult to control than the method used to make a panel of separate folded strips of material adhesively secured together. 
     The preferred cellular panel constructed and manufactured in accordance with the present invention overcomes these disadvantages. The panel can have cells of any desired shape, and can be made by a very efficient stacking process. In addition, only the front side of the panel requires a more expensive material, satisfying the aesthetic objectives of purchasers, and thus, the rear side can be made of a less expensive material, which is only required to reflect light, and aid in forming an insulating panel. 
     Many of the present features of the invention are applicable to another type of panel to be referred to as a light-controlling cellular panel, which is used to cover primarily windows. In this panel, the front vertical side of each horizontally extending cell is made of a sheer material, preferably of one mesh size, and the rear vertical side of each cell is made of a sheer material preferably of a different mesh size or mesh shape, to avoid a Moire effect. When the panel is in its light-passing state, the upper or lower horizontal wall of each cell is a horizontal opaque wall which, most desirably, is wider than the height of the cell. When one of the vertical sides of the panel is shifted upward or downward with respect to the other vertical side of the panel, the opaque walls are pivoted into substantially vertical positions where they completely overlap, to obstruct the passage of light through the panel. 
     Most of the methods previously used to fabricate this type of light-controlling panel did not permit the ready manufacture of any desired width of the panel. The commercial forms of this panel have been usually constructed from two horizontally spaced confronting unfolded vertical sheets of sheer material, which respectively formed the complete front and rear sides of the panel. Opaque strips of material are adhesively secured at spaced vertical points between the front and rear sheer sheets of the panel. The cells of this panel have a rectangular shape. As will later be described, the present invention provides a very efficient and effective means for manufacturing a panel having a similar appearance to this panel, but is constructed much differently. The present invention is made from a multiplicity of separate identical strips of material of any desired length, cut from a continuous web and laminated by an efficient strip stacking process where the panel can have any desired length. The panel can then be made into any width using a highly efficient stacking process. 
     SUMMARY OF THE INVENTION 
     It is preferred in all forms of the invention that the cellular panel be made by a method and with apparatus that initially is either a continuous tubular or flat web formed from two or more narrow, continuous substrate sheets or webs of completely different material which form the front and the rear walls of the cellular panel to be made therefrom. The continuous substrate sheets, when made of a thermoplastic material, are secured together, preferably by sonically welding their abutting longitudinal margins. This permits efficient mass production of panels of various constructions by cutting strips from the web and laminating the strips together in the various ways to be described. 
     One form of the invention forms a panel which is not light-controlling. The panels are made at a high-speed, on one or more production lines by feeding a pair of basic webs, or substrate sheets, in superimposed relation past one or more sonic welders. Where one sonic welder is used to make such a panel, the two continuous substrate sheets are welded together only along one of their longitudinal margins. The resulting two-substrate web is first unfolded to form a flat web. The flat web is fed, immediately and sequentially to folding, adhesive-applying, web cutting and stacking apparatus, or to a different production line when wound on a take-up reel and later unwound therefrom. The open tubular segments of the web formed by the folding apparatus produce adhesive connected tubular sections of the completed panel. 
     To avoid unfolding and folding the web, the web is formed by a pair of sonic welders which weld both aligned longitudinal margins of the superimposed continuous substrate sheets, so that the two-substrate web formed thereby forms a flat, closed tubular web; the welds are at the outer edges of the web. The flat, closed tubular web is fed to a web reforming apparatus. This apparatus first opens and then reflattens the web, so that the welds are transitioned to the flat top and bottom faces of the web. This reformed web is then subsequently fed to the adhesive-applying, web-cutting and stacking apparatus. 
     This web-reforming apparatus reflattens the tubular web in a plane preferably less than 90° from the original plane of the flat tubular web. This brings the welded margins of the flat tubular web from the outer edges of the flat web to laterally offset positions on the flat top and bottom faces of the web. As longitudinally-spaced segments of this flattened web become the separate tubular sections of the completed panel, the welded portions of these tubular sections are located along the confronting faces thereof, which are not visible at the front or rear side of the completed panel. The two different appearing substrate sheets are then only visible respectively on the opposite sides of the panel. While in accordance with a broad aspect of the invention, the welded portions need not be laterally offset, it is desirable because the offset reduces the thickness of the panel when it is raised into a collapsed condition at the top of a window. In all applications of the present invention where the substrate sheets are sonically welded along their superimposed abutting margins, it is desirable to flatten the welded portions of the substrate sheets. This process assures only a slight bulging of the substrate material therein, further reducing the thickness of the panel when in its collapsed configuration. 
     The welding and flattening of the substrate sheets is preferably achieved by a sonically welding method similar in some respects to that disclosed in U.S. Pat. No. 4,177,100 granted on Dec. 4, 1979 to Pennington. This patent discloses the use of heat and pressure to first secure together the folded trailing edge of a stationary thermoplastic sheet to the superimposed folded leading edge of a following stationary sheet. The welded superimposed stationary sheets are then unfolded and flattened by application of heat and pressure, while the sheets are stretched to pull the welded sheets apart. In the present invention, it is not necessary to pull the welded sheets apart during the application of the heat and pressure. In the practice of a preferred form of the present invention, the heat and pressure used to flatten the welds are applied by using sonic welding apparatus designed to perform only a weld-flattening operation. 
     In these two methods of making cellular panels, the individual tubular sections which form the completed panel can be formed from strips traversely cut from an adhesive coated web either before or after they are stacked. The latter stacking method is disclosed in U.S. Pat. No. 4,450,027 to Colson where, initially, an adhesive coated open tubular web, which is not a sonically-welded tubular web of different substrate sheets as just described, is spirally wound on a flat, rotating stacker. The stacker forms a flattened spiral winding of the web material, where the layers are adhesively secured together. The ends of this flat spiral winding are then severed from the rest of the stack of severed layers of material to separate and divide the severed web into separate, adhesively-secured together tubular sections forming a continuous cellular panel. However, it is preferred that the adhesively-coated, multi-substrate web be first cut into strips and then stacked in a manner like that disclosed in U.S. Pat. No. 3,713,914 to Clark et al. 
     When forming a light-controlling panel, the initial continuous web is constructed preferably of three, differently-appearing substrate sheets welded together at their confronting longitudinal margins. The central substrate sheet is made from an opaque material. The other two substrate sheets positioned on opposite sides of the opaque central substrate sheet, are made from a narrower sheet of sheer material preferably of different mesh size or mesh shape, to eliminate a Moire effect. The three-substrate web is preferably made by positioning one of the narrower sheer substrate sheets over and along one of the side margins of the wider opaque substrate sheet and positioning the other narrower sheer substrate sheet beneath the wider opaque web along the opposite side margin thereof. These substrate sheets so positioned are moved past a pair of sonic welders positioned along the opposite longitudinal margins of the substrate sheets, where each welder welds only the two layers of sheet material located thereat. The resulting three-substrate web is then unfolded so that the completed panel can be made by one of two methods. 
     In both of these methods, the three-substrate web is initially cut into strips of equal length. In another method, before the web is so cut, it is folded into an open tubular web by folding the opposite longitudinal margins of the outer sheer substrate sheets of the web over the central opaque substrate sheet of the web. A pair of adhesive bands are then applied to the top surfaces of the folded-over portions of the tubular web so that the tubular strips cut from the web are adhered together when stacked over a width equal to the width of the opaque substrate sheets thereof. The stacked, adhered strips are cut to size to form a continuous cellular panel of desired length. 
     When the panel is oriented so that the tubular sections or cells of the panel extend horizontally and are in vertically-spaced relation, the front wall of each cell is formed by a front vertical sheer substrate sheet of one of the tubular strips, the rear wall of each cell is formed by a rear vertical sheer substrate sheet of the same tubular strip, the bottom wall of each cell is formed by a horizontal center opaque substrate sheet of the same tubular strip and the top horizontal wall of each cell includes the folded end portions of the same tubular strip and the opaque substrate sheet of the strip above it. 
     When the substrate sheets which form the front or rear sides of the panel are shifted up or down with respect to each other, the initially horizontal opaque substrate sheets of the various laminated strips are shifted from a horizontal position where light passes through the panel to an inclined vertical position where the opaque substrate sheets of adjacent strips overlap, to stop the passage of light through the panel. 
     Another method for fabricating a light-controlling cellular panel eliminates the folding of the initially flat three-substrate webs. Before the flat web is cut into strips, spaced bands of adhesive are applied to the top surface of the web in a pattern which effects a special strip laminating pattern. The adhesive-coated flat web is then transversely cut into flat strips of equal length. The strips are laminated together by sequentially laterally shifting the strips from their original aligned longitudinally spaced positions. Each laterally shifted strip is next laminated so that the outer longitudinal margin of one of the outermost light-passing substrate sheets of each strip is adhered to the strip cut before it at the innermost longitudinal margin of the corresponding light-passing substrate sheet thereof, and the inner longitudinal margin of the other outermost light-passing substrate sheet of the former strip is adhered to the latter previously cut strip at the outer longitudinal margin of the corresponding outer substrate sheet. The resulting panel formed from the laterally-shifted laminated strips, when expanded, places the light-passing substrate sheets in positions where one of the light-passing substrate sheets of each strip forms a vertical front wall of an expanded tubular section of the panel, the other light-passing substrate sheet of the same strip forms a vertical rear wall of the adjacent expanded tubular section of the panel, and the opaque substrate sheet of that strip forms the horizontal top or bottom wall in common between adjacent cells of the panel. 
     When the light-passing substrate sheets on one side of the panel are shifted vertically relative to the light-passing substrate sheets on the opposite side thereof, the opaque central substrate sheet of each laminated strip of the panel is pivoted from its initial horizontal position where light can pass through the panel to a position where the opaque substrate sheets of adjacent cells of the panel overlap one another to obstruct the passage of light through the panel. 
     Other advantages and features of the invention will become apparent upon making reference to the specification, claims, and drawings to follow. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of two adjacent tubular sections of the preferred panel of the present invention which is adapted for applications where the panel covers a window in its normal use and is raisable to the top of a window when not in use; 
         FIG. 1A  is a fragmentary, enlarged vertical sectional view through the laminated portions of two adjacent tubular sections of the panel and shows spaced adhesive bands which secure together the adjacent wall sections of these tubular sections of the panel; 
         FIG. 2  is a larger perspective view of one of the tubular sections shown in  FIG. 1 , specifically showing the adhesive bands on the top of each tubular section; 
         FIGS. 3A-3F  respectively show the different operations performed on a production line upon a pair of superimposed continuous substrate sheets of different material to form a multi-substrate sheet web which is wound upon a reel and then subsequently unwound and applied to the second section of a production line, shown in block form in  FIG. 5 , where the web is coated with adhesive and cut into strips which are then laminated to form a continuous cellular panel; 
       FIGS.  4  and  4 ′ taken together show an exemplary production line for performing the various steps illustrated in  FIGS. 3A-3F ; 
         FIGS. 4A and 4B  disclose slit/weld sensor pins which detect whether the slit/weld anvils are operating properly; 
         FIGS. 4C-4H  disclose various views of the web reforming stations of the apparatus of FIG.  4 ′, where an initially formed flattened tubular web is reformed into a tubular web flattened in a different plane; 
         FIG. 4I  is a transverse vertical sectional view along section line  4 I— 4 I in FIG.  4 ′ through an ultrasonic horn assembly which sets a sharp fold in the side edges of the preformed web; 
         FIG. 4J  is a perspective view showing in more detail a portion of the stress-relieving station of the production line of FIG.  4 ′, which includes a heated cambered plate over which the re-formed web is fed; 
         FIG. 4K  is a longitudinal vertical sectional view along section line  4 K— 4 K in  FIG. 4J through a  pair of drive and nip rollers at one end of the cambered plate; 
         FIG. 4L  is a transverse vertical sectional view along section line  4 L— 4 L in FIG.  4 K through the nip roller assembly; 
         FIGS. 4M and 4N  show a modification of the production line of  FIG. 4 , where a number of multi-substrate webs are simultaneously formed on a number of production lines formed of common elements as in FIGS.  4  and  4 ′; 
         FIG. 4O  shows the different elements of a sonic horn used throughout the production lines to be described hereafter; 
         FIG. 5  is a block diagram showing how a multi-substrate web formed by the production line of FIGS.  4  and  4 ′ is further processed by applying adhesive to the web, cutting the web into strips, and then stacking the strips to form a completed continuous cellular panel; 
         FIG. 6  is a perspective view of two adjacent tubular sections of a panel where each tubular section is an open top tube for a panel which covers a window in its normal use and is raisable to the top of a window when not in use; 
         FIG. 6A  is a fragmentary enlarged vertical sectional view through the laminated portions of two adjacent tubular sections of the panel of FIG.  6  and shows spaced adhesive bands which secure together the adjacent wall sections of the tubular sections of the panel; 
         FIG. 7  is a larger perspective view of one of the tubular sections shown in  FIG. 6 , specifically showing the adhesive bands on the top of each tubular section; 
         FIGS. 8A-8F  respectively show the different operations performed on a production line upon a pair of superimposed continuous substrate sheets of different material to form a multi-substrate sheet web which is wound upon a reel and then subsequently unwound and applied to the second section of a production line where the web is folded, coated with adhesive and cut into strips which are then laminated to form the continuous cellular panel shown in  FIG. 6 ; 
         FIG. 9  shows part of a production line for performing the various steps which form the multi-substrate sheet web of  FIGS. 8A-8F ; 
         FIG. 10  is a block diagram showing how the multi-substrate web formed by the production line of  FIG. 9  is further processed by folding the multi-substrate web, applying adhesive to the web, cutting the web into strips and then stacking the strips to form a completed continuous cellular panel of  FIG. 6 ; 
         FIG. 11  is a perspective view of three adjacent cells of yet another embodiment of the present invention which is a light-controlling cellular panel and is adapted to applications where the front and rear sides of the panel are movable vertically relative to one another from the light-passing position of  FIG. 11  to one (not shown) where light passage through the panel is blocked; 
         FIGS. 11A-11B  more clearly show the spaced bands of adhesive which secure together the adjacent cells or tubular sections of  FIG. 11 ; 
         FIGS. 12A-12D  respectively show the different operations performed on a production line upon three superimposed continuous substrate sheets of different material to form a multi-substrate sheet web which is to form a light-controlling cellular web which is wound upon a reel and then subsequently unwound and applied to the second section of a production line shown in block form in  FIG. 14 , where the web is folded, coated with adhesive, and cut into strips which are then laminated to form the continuous cellular panel of  FIGS. 11 and 12 ; 
         FIG. 13  shows part of a production line for performing the various steps which form the multi-substrate sheet web of  FIGS. 12A-12D ; 
         FIG. 14  is a block diagram showing how the multi-substrate web formed by the production line of  FIG. 13  is further processed by folding the multi-substrate sheet web, applying adhesive to the web, cutting the web into strips and then stacking the strips to form the completed continuous cellular panel of  FIG. 11 ; 
         FIGS. 14A-14D  illustrate the tubular web produced by the production line of  FIG. 13  respectively, before the web is folded, after it is folded, after adhesive is applied to it, and after strips cut from it are laminated together; 
         FIG. 15  is a perspective view of a plurality of cells of another light-controlling panel embodiment of the present invention; 
         FIGS. 15A-15B  are fragmentary enlarged views of the panel of  FIG. 15  showing the adhesive bands connecting adjacent multi-substrate strips which form the cells of the panel; 
         FIG. 16  is the multi-substrate web produced by the production line in  FIG. 13  coated with bands of adhesive; 
         FIG. 17  shows a plurality of strips cut from the web of FIG.  16  and laterally shifted with respect to each other, with arrows indicating the points where the adhesive band coated on the strip will adhere the laterally shifted strips together, to form the light-controlling cellular panel of  FIG. 15 ; 
         FIG. 18  is a block diagram showing how the multi-substrate web formed by the production line of  FIG. 13  is further processed to form the light-controlling cellular panel of  FIG. 15 ; and, 
         FIG. 19  shows the strip delivery and lateral strip-shifting conveyor means used to laminate the multi-substrate strips together to form the light-controlling cellular panel of FIG.  15 . 
     
    
    
     DETAILED DESCRIPTION OF THE PRESENT INVENTION 
     The Embodiment of  FIGS. 1-5   
     While this invention is susceptible of many different forms, there is shown in the drawings and will herein be described in detail various preferred embodiments of the invention, with the understanding that the present disclosure is to be considered as an exemplification of the broad principles of the invention and is not intended to limit the broad aspects of the invention to the embodiments illustrated. The various different details of the various embodiments of the invention are, in some cases, due to their different applications and, in other cases, due to progressive improvements to earlier developed embodiments. 
     Referring now to the drawings,  FIG. 1  shows a portion of a non-light controlling closed tube cellular panel  10  in its expanded state, formed from laminated horizontally elongated vertically aligned tubular sections or cells  12 . This is the most preferred panel embodiment of the present invention where the panel is not light-controlling as are other panels to be described.  FIG. 2  shows a single cell or tubular section  12  of the cellular panel  10 . The cell  12  has a front wall portion  14  made from a first continuous thermoplastic substrate sheet  18 , having a desired aesthetic appearance, and a rear wall portion  16  made from a second continuous thermoplastic substrate sheet  20  of about the same thickness, length and width as the first sheet  18 . The second sheet  20  is made of different appearing, preferably much less expensive, light-reflecting material from the substrate sheet  18 . The cell  12  also has a top wall portion  15  and a bottom wall portion  17 . Each tubular section  12  is laminated to the next adjacent tubular section  12  by spaced bands  11 - 11 ′ of adhesive which are spaced apart to provide an adhesive-free band  15   a  centered on the top wall portion  15  of each cell  12  to receive a drill for drilling pull cord-receiving holes (not shown). Folds  13 - 13 ′, shown in  FIG. 1A , are formed in the centers of the sheets  18  and  20 , so that when the tubular sections  12  are expanded by the weight of a bottom rail (not shown) and the weight of the panel itself above the rail, the cells have a hexagonal shape. 
     The cell  12  is initially formed by first superimposing the two separate continuous substrate sheets  18 , 20  as shown in FIG.  3 A. The superimposed substrate sheets  18  and  20  have superimposed longitudinal marginal portions adjacent their longitudinal edges  22 , 22  and  22 ′, 22 ′ which are secured together, most preferably by sonic welding. As shown in  FIG. 3B , circular pointed slit/weld anvils  24 , 24 ′ are positioned slightly inward of the aligned pairs of longitudinal edges  22 , 22 ′ of the two substrate sheets  18 , 20 . The anvils  24 , 24 ′ may be driven by a pulley system (not shown) or other drive means or can be stationary. Driven rotary anvils are preferred to lessen the wear on the anvils. The periphery of each anvil  24 , 24 ′ is tapered on each side  24   b , 24   b ′ toward the pointed edge  24   a , 24   a ′ thereof. A common ultrasonic horn  26  having a flat end face  26   a  is positioned under the second substrate sheet  20  and extends at least the entire width of the two substrate sheets  18 , 20 . As the two substrate sheets  18 , 20  pass between the slit/weld anvils  24 , 24 ′ and the common ultrasonic horn  26 , the longitudinal marginal portions of the sheets inwardly of the pointed edges  24   a , 24   a ′ of the anvils  24 , 24 ′ are welded together by the ultrasonic horn  26  vibrating the two substrate sheets  18 , 20  against the slit/weld anvils  24 , 24 ′. Narrow continuous longitudinal welded portions  28 , 28 ′ are formed at the inside faces  24   b , 24   b  of the slit/weld anvils  24 , 24 ′. The welded portions  28 , 28 ′ have a width of about the thickness of each of the substrate sheets  18 , 20 .  FIG. 3C  is an enlarged view of a weld formed by the process shown in FIG.  3 B and shows the pointed edge  24   a ′ of the anvil  24 ′, the superimposed substrate sheets  18 , 20 , and a portion of the ultrasonic horn  26  positioned therebelow. 
     In addition to sonically welding the superimposed substrate sheets  18 , 20  together, the slit/weld anvils  24 , 24 ′ also slit through the superimposed substrate sheets  18 , 20  at the location of the anvil pointed edges  24   a , 24   a ′. This produces selvedge portions  32 , 32 ′ of the superimposed substrate sheets  18 , 20  adjacent the pointed edge  24   a , 24   a ′ of each slit/weld anvil  24 , 24 ′ which are collected in a process to be described in more detail. 
     The welding process described forms a continuous, flat, multi-substrate tubular web  30  ( FIG. 3B ) in a horizontal plane, with the different appearing substrate sheets  18 , 20  constituting the opposite flat sides thereof. The panel  10  is formed from longitudinally spaced segments cut from this web  30  and laminated preferably in a manner to be described. The web  30  shown is reformed so that a flat tubular web  30 ′ ( FIG. 3F ) is formed having the welded portions  28 , 28 ′ thereof on the top and bottom of the opposite flat sides of the reformed flattened web  30 ′. To this end, the tubular web  30  is first guided from a horizontal plane to a vertical plane (FIG.  3 D). The flat tubular web  30  is next opened and then flattened in a plane approaching a right angle to the original plane of the flat web  30  to bring the welded portions  28 - 28 ′ to the flat top and bottom faces of the reformed tubular web  30 ′, but laterally spaced in opposite directions from the center line of the web so the welded portions  28 - 28 ′ webs are not in alignment, as shown in FIG.  3 E. As there shown, the reformation of the web  30  causes the welded portions  28 - 28 ′ to project above and below the top and bottom faces of the reformed web  30 ′. It is desirable that the reformed tubular web  30 ′ have a similar thickness throughout; therefore, the projecting welded portions  28 - 28 ′ of the tubular web  30 ′ are flattened to produce a tubular web  30  with similar thickness throughout as shown in FIG.  3 F. 
       FIG. 3E  illustrates this weld flattening process which utilizes a weld flattening ultrasonic horn  33 , similar to the welding ultrasonic horn  26  shown in  FIG. 3B , but positioned above the reformed tubular web  30 ′, and a preferably driven cylindrical rotating anvil  34  positioned below the reformed tubular web  30 ′. As the tubular web  30 ′ passes between the web flattening ultrasonic horn  33  and the cylindrical rotating anvil  34 , the welded portions  28 , 28 ′ of the tubular web  30 ′ are flattened by the pressure applied by the flattening ultrasonic horn  33  vibrating the tubular web  30 ′ over the cylindrical rotating anvil  34 . The opposite top and bottom layers of the tubular web  30 ′ are not welded together because the conditions of the process are controlled to avoid a welding operation. Exemplary weld flattening conditions are disclosed in the process specification to follow. 
       FIG. 3F  shows the reformed tubular web  30 ′ with the welded portions  28 , 28 ′ out of alignment and substantially flattened. As shown, slight bulges  36 , 36 ′ remain in the tubular web  30 ′ at the welded portions  28 - 28 ′. 
     FIGS.  4  and  4 ′ show a full production line for manufacturing the closed reformed tubular web  30 ′ made of two continuous substrate sheets  18 , 20  of differently appearing material. FIG.  4 ′ is a continuation of the line shown in FIG.  4 . Narrow webs of the two continuous substrate sheets  18 , 20  wound on driven supply reels  40 ′, 42  are unwound by the pulling force of drive and nip rollers  35 , 37 . The substrate sheets  18 , 20  pass through a series of rollers designed to maintain tension in the substrate sheets  18 , 20 . To this end, the substrate sheets  18 , 20  first respectively pass over idler rollers  44 , and down under conventional dancer tensioning rollers  46  which are mounted on arms (not shown) which move up and down to keep a constant tension in the continuous substrate sheets  18 , 20 . The tendency of these and other dancing rollers, to be described, to move up and down is opposed by a feedback control system which controls the driving speed of the supply reels  40 , 42  and take-up reel  128  upon which the completed web  30  is wound. The substrate sheets  18 , 20  continue over second idler rollers  48 . After the substrate sheets  18 , 20  pass over idler rollers  48 , the first substrate sheet  18  passes through a conventional photo-cell controlled edge guidance roller assembly  50  which keeps the sheet in longitudinal alignment. The substrate sheet  18  next passes under a third idler roller  52  and to a pair of idler rollers  60 - 62 . The roller assembly  50  includes a support frame  50 ′ mounted for pivotal movement about a vertical axis and photo-cells  50 ″ sensing the positions of the edges of the substrate sheet  18 . After passing over the second idler roller  48 , the second substrate sheet  20  passes under the third idler roller  52  and through a conventional photo-cell controlled edge guidance roller assembly  50 , like the assembly  50  just described. The substrate sheet  20  then passes up to the pair of idler rollers  60 , 62 . At the idler rollers  60 , 62 , the superimposed substrate sheets  18 , 20  have their longitudinal margins or edges aligned. 
     The two superimposed substrate sheets  18 , 20  next pass through adjustable longitudinally-spaced non-rotating shafts  54 , 56 , 58 , which are vertically adjustable. The shafts  54 , 56  adjust the elevation of the two superimposed substrate sheets  18 , 20 . The shaft  58  is positioned below shafts  54 , 56  and is vertically adjustable to control tension in the substrate sheets  18 , 20  to eliminate any wrinkles at the welding assembly. The first substrate sheet  18  passes over the shaft  54  and between the shafts  56  and  58 . The second substrate sheet passes under the shaft  54  and between the two shafts  56  and  58 . 
     The superimposed substrate sheets  18 , 20  next pass between the common ultrasonic horn  26  and the rotating or stationery slit/weld anvils  24 , 24 ′, where the sheets&#39; opposite longitudinal edges  22 , 22 ′ are welded together, as previously described with respect to  FIGS. 3B-3C . This, as noted before, forms a continuous tubular web  30  of differently appearing substrate sheets  18 , 20  superimposed and welded together in the horizontal plane. The welding process carried out by the ultrasonic horn  26  and rotating slit/weld anvils  24 , 24 ′ produce selvedge portions  32 , 32 ′ at the longitudinal edges  22 , 22 ′ of the tubular web  30 . The tubular web  30  and selvedge portions  32 , 32 ′ then pass through a pair of slit sensor pins  59 , 59 . 
     The pair of slit sensor pins  59 , 59  are further shown in  FIGS. 4A and 4B  and extend upward from a common controlled shaft  59 ′. The sensor pins  59 , 59  pass between the selvedge portions  32 , 32 ′ and the welded portions  28 , 28 ′ of the substrate sheet  18 , 20  before the same reaches the rollers  35 , 37 . The sensor pins  59 , 59  detect whether the slit/weld anvils  24 , 24 ′ have completely slit through the substrate sheets  18 , 20  which would normally indicate that the slit/weld anvils  24 , 24 ′ are operating properly. The slit/weld anvils will wear over time and eventually fail to completely slit through the substrate sheets  18 , 20 . If this occurs, the portion of the substrate sheets  18 , 20  not slit engages the slit sensor pins  59 , 59 , which will rotate the common controlled shaft  59 ′ forward. As shown in  FIG. 4B , this forward rotation of the shaft  59 ′ is connected to a switch means  61  which shuts down the production line so that the worn, defective slit-weld anvil can replaced. 
     The tubular web  30  and selvedge portions  32 , 32 ′ next pass between a driven bottom roller  35  and a top nip roller  37 , which pull the substrate sheets  18 , 20  through the welding assembly. The selvedge portions are wound on take-up reel  64 . The tubular web  30  then passes over an idler roller  63  which restores the elevation of the tubular web  30  to the elevation occupied by the tubular web  30  at the welding apparatus. 
     After the welding, but before the weld flattening operation, as previously described, web-reforming means are provided which transition the welded portions  28 , 28 ′ of the tubular web  30  from the outer edges of the tubular web  30  to positions on top and bottom of a flat reformed tubular web  30 ′, as shown in FIG.  3 E. This transition of the welded portions  28 , 28 ′ preferably takes place in the specific manner illustrated in  FIGS. 4C-4H . 
     The tubular web  30  lies in a horizontal plane after exiting the ultrasonic horn  26  and slit/weld anvil  24 , 24 ′ assembly and is twisted into a vertical plane by passing through one of the vertical slots  67  formed between a first pair of spaced vertical rods  68 , 68  of a first comb-like structure  66  shown in FIGS.  4 ′ and  4 C. The vertical, horizontally spaced rods  68  are mounted on a base  66  supported on a post  67 . The tubular web  30  then passes through a second comb-like structure  66 ′ identical to the first comb-like structure  66 . Using two comb-like structures assures the tubular web  30  is kept in a vertical plane before it enters the next steps of the process; it also reduces stress on the web  30 . 
     The vertically oriented tubular web  30  is then expanded to receive an insert structure  70  illustrated in greater detail in  FIGS. 4D-4G . As seen in  FIG. 4D , the insert structure  70  floats within and keeps the tubular web  30  open, with the welds  28 , 28 ′ at the top and bottom of the web  30 . The tubular web  30  is then re-flattened in a plane slightly less than 90 degrees from the plane of the interfaces between the substrate sheets  18 , 20  when they were originally welded together.  FIG. 4E  shows the insert structure  70  including a pair of horizontally spaced vertical support plates  72 , 72 ′ between which are rotatably mounted two narrow, vertically spaced rollers  74 , 76  having outwardly tapering peripheral portions  74   a , 76   a  ending at peripheral flat crown portions  74   b , 76   b . A horizontal, rearwardly tapering guidance plate  78  is secured to the vertical support plates  72 , 72 ′ and extends forwardly therefrom. The tapered guidance plate  78  rests on a stationary shaft  86  for support.  FIG. 4F  illustrates in dashed lines a cross-section of the tubular web  30  passing around the insert structure  70 , with the flat crown portions  74   b , 76   b  of the roller peripheries engaging and expanding the open web, so that the welded portions  28 , 28 ′ at the top and bottom of the vertically oriented tubular web  30  ride along the flat crown portions  74   b , 76   b.    
     To prevent the guidance plate  78  from shifting in a lateral direction, a pair of rotatable plate-holding members  78 ′ are positioned on opposite sides of the guidance plate  78 . The members  78 ′ rotate while pressing against the outer sides of the web against the edge of the guidance plate  78  as shown in FIGS.  4 ′ and  4 F. 
     The expanded web  30  is then kept expanded in a horizontal plane by the guidance plate  78  and in a vertical plane by the flat crown portions  74   b , 76   b  of rollers  74 , 76 . A pair of fixed cylindrical outer guide members  77 , 79  are provided with tapered slotted portions  81   a , 83   a  which closely but in spaced relation confront the forwardly facing sides of the rollers  74 , 76  respectively at the upper and lower margins thereof. The outer guide members  77 , 79  are formed by a pair of bearings  77   a-b ,  79   a-b  with tapered confronting surfaces  77   a′-b ′ and  79   a′-b ′ which are spaced apart by O-rings  81 , 83  and define grooves  81   a , 83   a  with the tapered surfaces  77   a′-b ,  79   a′-b ′ closely confronting the flat crown portions  74   a-b , 76   a-b  of the rollers  74 , 76  of the insert structure  70 . The forward movement of the expanded web  30  pushes the insert structure  70  forward towards the outer guide members  77 , 79  so that the expanded web  30  is forced between the outer guide members  77 , 79  and the vertically spaced rollers  74 , 76 .  FIG. 4G  is a view of the top portion of FIG.  4 E. It shows the welded portion  28  riding along the flat crown portion  76   b  as the web  30  passes between the roller  76  and outer guide member  77 . 
     As seen in FIGS.  4 ′ and  4 H, after tubular web  30  passes around the insert structure  70 , the web  30  passes between a stationary grooved sleeve  86 ′ and a stationery grooved sleeve  87 ′. The insert structure guide plate  78  rests on the stationary shaft  86 . The sleeves  86 ′, 87 ′ are secured by one or more set screws  86 ″, 87 ″ to stationary shafts  86 , 87 . The shaft  87  is vertically adjustable and is located slightly downstream and above the shaft  86 . As best seen in  FIG. 4H , the sleeves  86 ′, 87 ′ have laterally offset grooves  88 , 89  into which the bulging welded portions  28 , 28 ′ of the web  30  enter respectively, to laterally offset the welded portions  28 , 28 ′. This lateral offset reduces the thickness of the completed cellular panel  10  when in a collapsed configuration because the welded portions  28 , 28 ′ slightly bulge the tubular web  30 . The grooved sleeves  86 ′, 87 ′ are positioned by set screws  86 ″ and  87 ″ to obtain the desired offset positions. The stationary shafts  86 , 87  may carry additional grooved sleeves if manufacturing a plurality of webs at the same time, as seen in  FIGS. 4M and 4N . 
     The web  30 , after leaving the grooved sleeves  86 ′, 87 ′, enters the weld flattening assembly comprising the flattening ultrasonic horn  33  and cylindrical rotating anvil  34  shown in FIG.  3 E. The top and bottom welds  28 , 28 ′ are located to the right and left of center lines of the top and bottom walls of the reformed web  30 ′, as shown in FIG.  3 E. The reformed tubular web  30 ′ passes between the flattening ultrasonic horn  33  and cylindrical rotating anvil  34  shown in  FIG. 3E  which flattens the projecting weld  28 , 28 ′ of the reformed tubular web  30 ′ to produce a web of similar thickness throughout. 
     As shown in FIGS.  4 ′ and  4 I, the reformed web  30 ′ passes between another ultrasonic horn  92  and a cylindrical rotating anvil  94  similar to the weld flattening assembly previously described. This second ultrasonic horn  92  vibrates the reformed web  30 ′ against the second cylindrical rotating anvil  94  to set the folds made at the outer longitudinal edges of the reformed web  30 ′. As best seen in  FIG. 4I , the second cylindrical rotating anvil  94  has a recessed portion  96  substantially at its center where the welded portions  28 , 28 ′ pass through. Without the recessed portion  96 , the bulging welded portions of the web  30 ′ would become heated to a much higher temperature than the rest of the web, which could cause a possible undesired welding together of the overlying layers of the web. This prevents the second ultrasonic horn from working directly onto the welded portions  28 - 28 ′ and concentrates the work performed on the longitudinal edges of the reformed web  30 ′. 
     After this foldsetting, the reformed web  30 ′ passes between drive roller  110  and nip roller  112  (FIG.  4 ′). The nip roller  112  is a bias controlled roller. The nip roller  112  is, thus, adjustable allowing the nip roller  112  to apply more pressure to one side of the reformed web  30 ′ than the web&#39;s other side. Such a roller improves the control over the path of the web. The thicknesses of the substrate sheets  18 , 20  forming the web  30 ′ can be different. Due to this possible variation in thickness, the web may try to move laterally as it passes between the drive and the nip rollers  110 , 112 . The bias control nip roller  112  prevents any lateral movement of the web  30 ′ and assures the web  30 ′ travels in a straight path. 
       FIGS. 4K and 4L  illustrate the bias control nip roller  112  in more detail.  FIG. 4K  is a side view of the nip roller  112  taken along the line  4 K— 4 K in FIG.  4 J.  FIG. 4L  is a cross-sectional view taken along the line  4 L— 4 L in FIG.  4 K. The nip roller  112  has a grooved sleeve  130  which rides about a plurality of bearings  131  adjacent a common shaft  132 . The grooved sleeve has outer sections  133 , 134  which contact the reformed web  30 ′. The grooved sleeve  130  allows the welded portions  28 , 28 ′ to pass without contacting the nip roller  112 . Spring assemblies  135 , 136 , located on each end of the shaft  132 , apply pressure independently to each outer section  133 , 134  of the nip roller  112 . Set screws  137 , 138  allow the pressure to be adjusted on each outer section  133 , 134  of the nip roller  112 . As described before, more pressure can then be applied to one side of the reformed web  30 ′ than the other to prevent any lateral movement of the web  30 ′ due to the different thicknesses of the substrate sheets  18 , 20 . 
     The web  30 ′ is next pulled under tension over a heated upwardly honed or cambered plate  106 , as shown in FIG.  4 ′ and  FIG. 4J , to relieve the stresses produced in the flattened welded portions  28 , 28 ′ of the reformed tubular web  30 ′. The cambered plate  106  is heated by a heating element  108  positioned below the plate. The tubular web  30 ′ is forced downward against the heated cambered plate  106  by the passage of the web  30 ′ between drive and nip rollers  110 , 112 , the nip roller  112  being positioned below the lower inlet end of plate  106  and then between drive and nip rollers  116 , 114  at the outlet end of the plate  106  as seen in FIG.  4 ′ and FIG.  4 J. 
     Nip roller  114  is also a bias control roller, identical to nip roller  112 , to assure the web passes over the upwardly honed cambered plate  116  in a straight path. 
     Heating the reformed tubular web  30 ′ under tension relieves stresses produced in the welded portions  28 , 28 ′ of the tubular web by the welding process. These stresses are apparent by a longitudinal bow in the reformed tubular web  30 ′ and ripples at the welds  28 , 28 ′ prior to passing over the heated cambered plate  106 . The relief of these stresses in the welds  28 , 28 ′ minimizes any ripples and produces a flat, unbowed tubular web  30 ′. 
     As seen in FIG.  4 ′, the reformed tubular web  30 ′ passes under a further idler roller  118 , over an adjacent idler roller  120  and passes under a dancer tensioning roller  122  which controls tension in the web  30 ′. The web  30 ′ proceeds over the two idler rollers  124 , 126  to an individual powered take-up reel  128  for later fabrication, as shown in  FIG. 4 , or is immediately processed to form the cellular panel  10 . 
     Although  FIGS. 4A-4L  show the manufacture of only one tubular web  30  at a time, the comb-like structure  66  ( FIG. 4N ) has a plurality of vertical rods  68  to receive a number of tubular webs  30   a - 30   d  simultaneously. Such a modified production line is shown in FIG.  4 M. As seen in  FIG. 4M , a number of tubular webs  30   a - 30   d  can be manufactured from a wider, continuous tubular web of a pair of supplemental continuous substrate sheets  18   a , 20   a . The continuous substrate sheets  18   a , 20   a , made of similar material as substrate sheets  18 , 20 , are unwound from powered supply reels (not shown) and pass through a similar set of rollers (like rollers  44  through  60 ), as shown in FIG.  4 . These rollers are wider, however, to accommodate the wider substrate sheets  18   a , 20   a . The superimposed wider substrate sheets  18   a , 20   a  then are passed between a common ultrasonic horn  26 ′ vibrating the wider superimposed substrate sheets  18   a , 20   a  against a plurality of laterally spaced rotating slit/weld anvils  24 ′ positioned adjacent to one another. This produces a plurality of closed welded tubular webs  30   a - 30   d  which pass through a plurality of slit sensor pins  59  (as described before). The webs  30   a - 30   d  pass between the vertical rods  68  in the comb-like structures  66 , 66 ′ ( FIG. 4N ) Each tubular web  30   a - 30   d  is then further processed in the manner just described and wound onto separate reels. 
     Exemplary specifications for some of the production lines described include a sonic horn like that shown in FIG.  40 . The sonic horn is connected to a booster B 1  driven by a converter C 1  which is fed from a commercial AC power line. 
     The following are a set of exemplary specifications for the production line shown in FIGS.  4  and  4 ′:
         1. Web feed speed: 17.5 feet per minute   2. Specification of substrate sheet  18 : 0.007″ thick woven polyester fabric.   3. Specification of substrate sheet  20 : 0.007″ thick non-woven polyester fabric.   4. Specification of sonic welder ultrasonic horn  26 :
           a. power supply; converts 50/60 Hz line current to 20 KHz electrical energy;   b. converter; converts electrical oscillations into mechanical vibrations.   c. booster (1:2 ratio); modifies the amplitude of vibrations.   d. amplitude (65% setting at power supply control); function of horn shape, peak to peak displacement of the horn at its work face.   e. horn; ½″×9″ carbide tipped face titanium.   f. manufactured by Branson Ultrasonics Corporation, 41 Eagle Road, Danbury, Conn. 06813 identified by Model Number 900B.   
           5. Specification of slit/weld anvil  24 : stationary, 1″ diameter, ⅛″ wide, 150 degrees, 0.005 r.   6. Slit/weld anvil  24  pressure against web: 40 PSI.   7. Specification of weld-flattening ultrasonic horn  33 :
           a. power supply; converts 50/60 Hz line current to 20 KHz electrical energy;   b. converter; converts electrical oscillations into mechanical vibrations.   c. booster (1:1.5 ratio); modifies the amplitude of vibrations.   d. amplitude (80% setting, pneumatic engagement and retraction.   e. horn; ½″×9″ carbide tipped face titanium.   f. manufactured by Branson Ultrasonics corporation, 41 Eagle Road, Danbury, Conn. 06813 identified by Model Number 900AO.   
           8. Specification of weld-flattening cylindrical anvil  34 : 4″ diameter, driven at 17.85 feet per minute (2% overdrive for web tensioning).   9. Specification of grooved guide rollers  77 , 79 : ⅞″ diameter, {fraction (1/16)}″ spacing (o-ring), 1⅞″ vertical distance between upper and lower pairs.   10. Specification of guide plate  78 : 0.030″ thick, {fraction (9/16)}″ to 1{fraction (5/16)}″ taper over 9½″ distance.   11. Specification of foldsetting ultrasonic horn  92 :
           a. power supply; converts 50/60 Hz line current to 20 KHz electrical energy;   b. converter; converts electrical oscillations into mechanical vibrations.   c. booster (1:1.5 ratio); modifies the amplitude of vibrations.   d. amplitude (80% setting, pneumatic engagement and retraction.   e. horn; ½″×9″ carbide tipped face titanium.   f. manufactured by Branson Ultrasonics Corporation, 41 Eagle Road, Danbury, Conn. 06813, identified by Model Number 900AO.   
           12. Specification of foldsetting cylindrical anvil  94 : 4″ diameter, driven at 17.85 feet per minute (2% overdrive for web tensioning) with weld seam clearance relief.   13. Pneumatic pressure exerted by weld-flattening ultrasonic horn  33  against weld-flattening cylindrical anvil  34 : 12-14 PSI.   14. Pneumatic pressure exerted by foldsetting ultrasonic horn  92  against foldsetting cylindrical anvil  94 : 22-24 PSI.   15. Specification of nip rollers  112 , 114 : 1⅛″ wide, 2″ diameter, ¼″ wide groove.   16. Specification of heated cambered plate  106 : 230 degrees F., ½″ rise at center 24″ length.   17. Specification of drive roller peripheral speed: 17.94 feet per minute (0.5% tensioning overdrive).       

       FIG. 5  is a block diagram illustrating the steps of forming a cellular panel  10 , from a continuous flat reformed tubular web like web  30 ′, 30   a , 30   b , 30   c  or  30   d . The functions performed by the blocks shown therein may be performed, for example, by the tension control web aligning, adhesive applying, and web cutting and stacking chamber disclosed in U.S. Pat. No. 4,450,027 or copending application Ser. No. 07/839,600 filed Feb. 28, 1992. A pair of reels of a pair of reformed webs  30   a ′ and  30   b ′ are shown in  FIG. 5  supported one above the other. The web  30   a ′ on one reel is unwound in a horizontal plane while it passes first through tension control and web aligning means  41  comprising rollers (not shown) to maintain tension and laterally align the tubular web  30   a ′. The tubular web  30   a ′ then passes through an adhesive applying means  43  which applies the two bands  11 , 11 ′ of adhesive, (FIG.  1 ). The two bands of adhesive  11 , 11 ′ are applied to the portion of the web  30   a ′ to form the top wall portion  15  of each cell  12  formed from the tubular web  30   a , (FIG.  2 ). As shown in  FIG. 1A , the bands of adhesive  11 , 11 ′ are applied over the welded portions  28 , 28 ′ of the tubular web  30   a ′ to reinforce the welds. The bands of adhesive  11 , 11 ′ are spaced to leave the center portion of the top wall portion  15  of the tubular web  30   a ′ free of adhesive. This allows for drilling through the center of the top wall portion  15  of the tubular web  30 ′ to accommodate the drawstrings of a complete cellular panel  10  without the drilling means coming into contact with the adhesive. If adhesive was applied along the entire top wall portion  15 , the drilling means would have to be periodically cleaned or replaced after the adhesive built up on the drilling means. 
     Referring again to  FIG. 5 , the tubular web  30   a ′ is then cut into identical tubular strips by a cutting means  45 . The strips cut from the web  30   a ′ form the cells or tubular sections  12  of the panel  10 . The web  30   a ′ is then fed by high speed conveyor means  47  to a stacking chamber  49 , both similar to that disclosed in U.S. application Ser. No. 839,600. The stacking chamber  49  receives the flat tubular strips through a strip pass-through slot (not shown) located in the floor of the stacking chamber extending the length of the tubular strips. The conveyor means  47  includes a stationary conveyor belt section  47   a  which separates the cut strips and a raisable conveyor section  47   b  which is raised by a lifter means  51 . The conveyor sections  47   a , 47   b  may each include suction conveyor belts which hold the strips by suction thereon. The lifter means  51  raises the raisable conveyor  47   b  through the slot in the floor of the stacking chamber  49 . This pushes the strip, held on the belts by suction, off the belts and up against the strip above it. This strip is thus raised in the stacking chamber  49 , so that the adhesive bands  11 , 11 ′ adhere to the bottom of the strip above it, as shown in FIG.  1 A. The movement of the belt forming the raisable conveyor  47   b  is stopped when a strip is in alignment along its length with the inlet slot of the stacking chamber  49 . 
     To properly align the tubular strips in the stacking chamber  49 , the bottom of the stacking chamber may be defined by a pair of vertical confronting walls (not shown) which are spaced apart a distance slightly greater than the width of the strips. These walls thus laterally align each strip being pushed into the stacking chamber with the strip above it. The upper portion of the stacking chamber preferably has opposite upwardly diverging walls so that the laminated strips raised momentarily in the chamber will not get stuck in the chamber. The proper timing of the operation of all of the stations of the production line shown in  FIG. 5  is determined by suitable and conventional control means identified by a block  53  in FIG.  5 . 
     After a strip is pushed into the stacking chamber and adhered to the strip above it, the lifter means  51  lowers the raisable conveyor  47   b  which passes down through the pass-through slot in the bottom of the stacking chamber  49 . The strip just stacked separates from the raisable conveyor as it is pulled against the floor of the chamber  49  by the downward movement of the raisable conveyor  47   b . The movement of the belt of the raisable conveyor  47   b  then resumes as it receives the next strip to be pushed into the stacking chamber  49 . The sequence of operation just described is repeated to form the expandable cellular panel  10  in a mass production operation. When one of the web reels  30   a ′ is completely unwound, a photo cell (not shown) senses this condition and stops the web feed. The leading edge of the other reel, for web material  30   b ′, is then spliced to the trailing edge of the completely unwound web  30   a′.    
     Embodiment of  FIGS. 6-10   
       FIGS. 6-10  illustrate another embodiment of the present invention where a non-light controlling cellular panel  10 ′ is made similar to the panel  10  shown in  FIG. 1 , except that it is formed from a plurality of horizontally elongated open top tubular sections  12 ′ or cells rather than closed tubular sections.  FIG. 6  shows a portion of such a cellular panel  10 ′. As seen in  FIG. 7 , each tubular section  12 ′ is formed of front and rear substrate sheets  18 ′, 20 ′ of two differently appearing substrate materials. Each tubular section  12 ′ has a top wall portion  15 ′, formed by spaced inturned longitudinal margins of the substrate sheets  18 ′ and  20 ′, a bottom wall portion  17 ′ formed by the opposite longitudinal margins of the substrate sheets welded together at  28   a , and front and rear wall portions  14 ′ and  16 ′ respectively formed by the sheets  18 ′ and  20 ′. Each tubular section  12 ′ is formed from strips cut from a folded continuous two-substrate web formed by folding the initially flat web  31 , (FIG.  8 F). The outer longitudinal marginal portions of the unfolded continuous multi-substrate web  31  are folded over the central portion of the web to form an open tubular flat web which is coated with adhesive, cut into strips, and the adhesive-coated strips are sequentially stacked. The flat web  31  is made in the manner shown in  FIGS. 8A-F . 
       FIG. 8A  shows two differently appearing substrate sheets  18 ′, 20 ′ with their opposite longitudinal edges  22 , 22 ′ aligned.  FIG. 8B  shows the substrate sheets  18 ′, 20 ′ superimposed with only one of their aligned longitudinal edges  22 , 22 ′ being welded together at  28   a . The substrate sheets  18 ′, 20 ′ pass between a preferably driven rotating slit/weld anvil  24  and an ultrasonic horn  26 . This assembly is similar to that used in the welding process described with respect to the closed tubular web  30  in  FIGS. 1-5 . The ultrasonic horn  26  vibrates against the rotating slit/weld anvil  24 , welding the substrate sheets  18 ′, 20 ′ together to form a continuous folded tubular web  31  open at one end. This process produces a selvedge portion  32 ′ which is collected. The web is then unfolded to form the flat web  31  shown in FIG.  8 D and the weld  28   a  is flattened by a flattening ultrasonic horn  33  pressing the downwardly projecting weld against a cylindrical driven rotating anvil  34 , as shown in FIG.  8 E. The cylindrical rotating anvil  34  is driven. The weld flattening process just described leaves just a slight bulge  36  in the open multi-substrate web  31 . 
       FIG. 9  illustrates a portion of the production line utilized in manufacturing the open tubular web  31 . The production line has two powered supply reels  40 ′, 42 ′ of the substrate sheets  18 ′, 20 ′ made of different material. The substrate sheets  18 ′, 20 ′ pass through an identical roller set up (not completely shown) as previously discussed for the closed tubular web  30  which tensions the substrate sheets  18 ′, 20 ′ and superimposes the opposite longitudinal edges  22 , 22 ′ of the substrate sheets  18 ′, 20 ′. 
     The substrate sheets  18 ′, 20 ′ are then welded together at one of their aligned longitudinal edges  22 , 22 ′ by the vibrating ultrasonic horn  26  and slit/weld anvil  24  assembly, as previously described with respect to FIG.  8 B. The selvedge portion  32 ′ produced by the welding process is also wound upon a driven take-up reel  64 . After the substrate sheets  18 ′, 20 ′ are welded together, a continuous open tubular web  31  is formed having different appearing substrate materials. The open tubular web then passes between drive roller  35  and nip roller  37  which pull the substrate sheets  18 ′, 20 ′ through the welding assembly  24 , 26 . Although not shown in  FIG. 9 , it is understood that the open tubular web  31  can also pass through slit sensor pins as described. 
     The open tubular web  31  is then unfolded prior to entering the weld flattening assembly to form an unfolded flat multi-substrate web. To aid in unfolding the open tubular web  31 , the open tubular web  31  passes under a skewed roller assembly  75  made up of skewed top driven rollers  75   a , 75   a  which exert outward forces on the web  31  and a driven bottom roller  75   b . The unfolded multi-substrate web  31  then passes between two idler rollers  81 , 83 , and under a dancer tensioning roller  85 , which controls tension in the web  31  by adjusting the speed of the driven supply and take-up reels  40 ′, 47 ′, 128 . The web proceeds over a further idler roller  87  before entering the weld flattening apparatus. The welded portion  28   a  of the open multi-substrate web  31  is then flattened by the flattening ultrasonic horn  33  and cylindrical rotating anvil  34 , as previously described with respect to  FIGS. 8C-8E . 
     After the flattening process, the flat open multi-substrate web  31  passes between drive and nip rollers  110 , 112  and over a heated cambered plate  106  to relieve the stresses produced in the welded portion  28   a  of the open multi-substrate web  31  from the welding process as seen in FIG.  9 . The heated cambered plate  106  is identical to that described in the embodiment for the closed tubular web  30  with respect to  FIGS. 1-5 . The heat subjected to the open multi-substrate web  31  relieves the stresses in the welded portion  28   a , thus minimizing ripples and producing a flat, as well as straight open multi-substrate web  31 , which then can be processed further with less difficulties. 
     The open multi-substrate web  31  continues between drive and nip rollers  114 , 116 , and under a dancer tensioning roller  119 , which controls tension in the web  31 . The web  31  proceeds over an idler roller  121  to an individual powered take-up reel  128  for later fabrication as shown in  FIG. 9 , or is immediately processed to form the cellular panel  10 ′. 
       FIG. 10  is a block diagram illustrating the steps in forming the open cellular panel  10 ′ of  FIG. 6  formed from the flat web  31 . It is very similar to the process for making the cellular panel  10  formed by the closed tubular web  30  as previously discussed with respect to  FIGS. 1-5 . Accordingly, similar stations in  FIG. 10  have been identically numbered to those in FIG.  6 . One difference is the addition of folding means  55  before the adhesive applying means  43 . A suitable folding means is disclosed in U.S. Pat. No. 4,450,027 or in U.S. application Ser. No. 08/040,869, filed on Mar. 31, 1993, entitled “Folding Plate Assembly For Fabricating Honeycomb Insulating Material” and filed in the names of Bryan K. Ruggles and Cary L. Ruggles. As disclosed in that application, the folding means includes a slot folding plate assembly through which the web  31  passes. The slot is shaped to cause the outer longitudinal edges of the flat multi-substrate web  31  to raise above and over the central portion of the web  31 , thus folding the web. The confronting longitudinal margins of the folded web which form the top wall portion  15 ′ of the folded web do not contact one another, leaving a gap  57  in the top wall portion  15 ′ (FIG.  6 A). The folding means  55  may also include a fold setting means in the form of a heated drum (not shown) which heats the web material to its heat set temperature. The heated folded web is pressed against the drum to form sharp permanently set folds. A cooling means (not shown) then cools the pressed web below the setting temperature forming set pressed folds  13 , 13 ′ shown in  FIGS. 6 and 7 . 
     The tubular web  31  next passes through adhesive applying means  43  which applies two bands of adhesive  11 - 11 ′ on the top wall portion  15 ′ of the open tubular web  31  (FIG.  7 ). The open tubular web  31  is then cut into identical tubular strips by cutting means  45  which, by conveyer means, are fed to a stacking chamber  49  which may be similar to that disclosed in U.S. application Ser. No. 07/839,600, as previously discussed in detail with respect to the closed tube cellular panel  10  of  FIGS. 1-5 . 
     Embodiment of  FIGS. 11-14   
       FIGS. 11-14  illustrate a light controlling cellular panel  10 ″ of the present invention. It comprises horizontally elongated vertically aligned cells or tubular sections  12 ″ formed from an open flat tubular web  30 ″. The web  30 ″ is folded, coated with adhesive, and cut into strips; the strips are then stacked in the manner previously described. An opaque substrate sheet  19 ″ in each tubular section  12 ″ controls light passing through the panel  10 ″. When the opaque substrate sheet  19 ″ is rotated to a vertical plane, light passing through the panel is obstructed. 
       FIG. 11  shows a portion of the light-controlling cellular panel  10 ″. The cellular panel  10 ″ is formed by laminating separate open tubular strips when in a flattened condition, as shown in  FIGS. 14C and 14D , to form a tubular section  12 ″. Each cell  12 ″ has a front wall portion  14 ″ made of a sheer substrate sheet  18 ″ of one mesh size, a rear wall portion  16 ″ made of a sheer substrate sheet  20 ″ of a different mesh size, a bottom wall portion  17 ″ made of a wider substrate sheet  19 ″ of opaque material, and a top wall portion  15 ″ which is formed by the bottom wall portion  17 ″ of an adjacent call  12 ″ and the inwardly turned upper ends of the substrate sheets  18 ″, 20 ″ secured to the opaque sheet  19 ″ by spaced bands of adhesive  11 ″. 
     The open tubular strips are first formed from a flat continuous web  30 ″ made of three separate substrate sheets  18 ″, 19 ″, 20 ″ ( FIG. 12A ) which are welded together along their longitudinal margins.  FIG. 12A  shows the three superimposed substrate sheets  18 ″, 19 ″, 20 ″ with the left longitudinal edges  22 ′ and  22 ″ of the wider central opaque substrate sheet  19 ″ and lower sheer substrate sheet  20 ″ aligned, and the right longitudinal edges  22 ″ and  22  of the central opaque substrate sheets  19 ″ and upper sheer substrate sheet  18 ″ aligned. As seen in  FIG. 12B , the three-substrate sheets  18 ″, 19 ″, 20 ″ are welded together at their aligned two-substrate thick longitudinal edges by passing the substrate sheets  18 ″, 19 ″, 20 ″ between a common vibrating ultrasonic horn  26  and slit/weld anvils  24  identical to the welding apparatus as previously described. Thus, outer sheer substrate sheet  18 ″ is welded to the wider opaque substrate sheet  19 ″ at the right aligned longitudinal edges thereof while the other outer sheer substrate sheet  20 ″ is simultaneously welded to the opaque substrate sheet  19 ″ at the aligned left longitudinal edges thereof to form a Z-shaped web  30 ″ which is unfolded, as shown in FIG.  12 C. When unfolded, the web  30 ″ has a center opaque substrate sheet  19 ″ and outer sheer substrate sheets  18 ″, 20 ″ all in the same plane. 
     After the welding process, the welded portions  28 ″ of the unfolded web  30 ″ are flattened to form a flat web of similar thickness throughout. As seen in  FIG. 12D , the welded portions  28 ″ are flattened by passing the flat multi-substrate web  30 ″ between the flattening ultrasonic horn  33  and cylindrical rotating anvil  34 . The pressure applied by the flattening ultrasonic horn  33  to the welded portions  28 ″ of the multi-substrate web  30 ″ against the cylindrical rotating anvil  34  flattens the welded portions  28 ″ to produce a multi-substrate web  30 ″ with similar thickness throughout. 
       FIG. 13  shows a portion of the production line for manufacturing the continuous flat multi-substrate web  30 ″. The production line begins with driven reels  40 ″, 41 ″ and  42 ″ of continuous substrate sheets  18 ″, 19 ″ and  20 ″ unwinding the sheet material therefrom. The substrate sheets  18 ″, 19 ″, 20 ″ pass through similar sets of web-tensioning rollers (not shown) as discussed previously. The three-substrate sheets  18 ″, 19 ″, 20 ″ are then superimposed with their longitudinal edges aligned as described, by passing them in superimposed relation between a pair of idler rollers  60 ″, 62 ″ with one outer sheer substrate sheet  18 ″ on top, the center opaque substrate sheet  19 ″ in the middle, and the outer sheer substrate  20 ″ on the bottom of the superimposed stack of sheets. 
     Each outer sheer substrate sheet  18 ″, 20 ″ is then simultaneously welded to the longitudinal edge of the center opaque substrate sheet  19 ″ in alignment therewith by vibrating ultrasonic horn  26  and against the slit/weld anvils  24 , as previously described with respect to FIG.  12 B. The selvedge portions  32 ″ produced by the welding process are also rewound by take-up reels  64 ″. After the substrate sheets  18 ″, 19 ″, 20 ″ are welded together, a Z-shaped web  30 ″ as formed. The Z-shaped web passes between a drive roller  35 ″ and a nip roller  37 ″ which act to pull the substrate sheets  18 ″, 19 ″, 20 ″ through the welding assembly. Although not shown in  FIG. 13 , it is understood that the web  30 ″ can also pass through slit sensor pins as previously described with respect to the closed-tube cellular panel  10 . 
     As previously described, the Z-shaped web  30 ″ is then unfolded before entering the weld flattening apparatus to form a flat substrate sheet. To aid in the unfolding, the Z-shaped web  30 ″ passes beneath a skewed roller assembly  75 ″ comprised of driven upper rollers  75   a ″, 75   b ″, 75   c ″ and bottom roller  76   d . The driven rollers  75   a ″ and  75   c ″ overlying the outer sheet substrate sheets  18 ″,  20 ″, exert downward and outward forces on the outer sheer substrate sheets  18 ″ and  20 ″. A transversely extending roller  75   b ″ overlying the central opaque sheet  19 ″ exerts a downward force on the center opaque substrate sheet  19 ″ passing beneath the same. The flat multi-substrate web  30 ″ then passes over an idler roller  83 ″, under a dancer tensioning roller  85 ″ and over a second idler roller  87 ″. The projecting welded portions  28 ″ of the multi-substrate web  30 ″ are then flattened by the flattening ultrasonic horn  33  and cylindrical rotating anvil  34 , as previously described with respect to FIG.  12 D. 
     After the flattening process, the flattened multi-substrate web  30 ″ passes between drive and nip rollers  110 ″, 112 ″ and then over a heated cambered plate  106  to relieve the stresses produced in the welded portions  28 ″ of the multi-substrate web  30 ″ from the welding process. The heated cambered plate  106  is identical to that described in the embodiments of  FIGS. 1-5 . 
     The multi-substrate web  30 ″ then continues between further drive and nip rollers  114 ″, 116 ″, under a dancer tensioning roller  118 ″ and over an idler roller  120 ″ to either an individual driven take-up reel  128 ″ for later fabrication as shown in  FIG. 13 , or immediately processed to form the cellular panel  10 ″. 
       FIG. 14  shows a block diagram illustrating the steps of forming the light controlling cellular panel  10 ″ formed from the flat unfolded multi-substrate web  30 ″. It is very similar to the process utilized to make cellular panel  10 ′ formed from an open tubular web in accordance with FIG.  10 . Accordingly, corresponding reference numerals are used in  FIG. 14  to avoid a repetition of description. However, the folding means  55 ′ is different from the folding means  55  in  FIG. 10  which forms sharp set folds  13 ′- 13 ′ in the web  31 ′. The folding means  55 ′ includes no heated drum or other means to set any folds so that, as shown in  FIG. 11 , there are no folds seen at the sides of the rectangular tubular sections. The folding means, therefore, preferably includes only a slot forming plate, as shown in copending application Ser. No. 839,600. 
       FIGS. 14A-14D  illustrate respectively transverse sections of the web  30 ″ as it unwinds from the reel  128 ″, and when it leaves the folding means  55 ′ and adhesive applying means  43 . Note that in  FIG. 14C  the bands of adhesive  11 ″- 11 ″ deposited by the adhesive applying means  43  on the folded-over marginal portions of the outer substrate sheets  18 ″ and  20 ″ overlie the outer marginal portions of the opaque substrate sheet  19 ″.  FIG. 14D  shows adjacent strips S 1  and S 2  cut from the web  30 ″ pushed in the stacking chamber  49  where these strips are laminated together by the adhesive bands  11 ″- 11 ″. Thus, when a panel  10 ″, shown in  FIG. 11 , is allowed to expand, the calls or tubular sections have the rectangular shape shown therein. 
     When the outer sheer substrate sheets  18 ″, 20 ″, which form the front or rear wall portions  14 ″ or  16 ″ of the cellular panel  10 ″, are shifted up or down with respect to each other, the wide opaque substrate sheets  19 ″ of the various laminated strips shift from a horizontal position where light passes through the cellular panel  10 ″. The opaque substrate sheets  19 ″ are then inclined upwardly to an upstanding position where the opaque substrate sheets  19 ″ of adjacent strips overlap, because they are wider than the outer substrate sheets  18 ″, 20 ″. In this position, the passage of light through the panel  10 ″ is prevented. 
     Embodiment of  FIGS. 15-19   
     Another method of making a light controlling cellular panel comprising of horizontally elongated vertically aligned cells utilizes an unfolded substrate web  30 ″ identical to that formed by the production line shown in FIG.  13 . However, the web  30 ″ is processed differently, as illustrated in  FIGS. 16-19 , to produce a panel  10 ′″ shown in  FIG. 15  which shows a portion of the panel  10 ′″.  FIG. 16  shows the multi-substrate web  30 ″ with bands of adhesive B and B′ applied along the outer longitudinal margin, of the rear sheer substrate sheet  20 ″, and along the front margin of the opaque sheet  19 ″ opposite the inner or front margin of the sheer substrate sheet  20 ″. The web  30 ″ is then cut into strips sequentially to form three-substrate strips S 1 , S 2 ,S 3 , etc. as shown in FIG.  17 . 
     The closed tube cellular panel  10 ′″ is formed by laminating in sequence the flat unfolded multi-substrate strips S 1 ,S 2 , etc. together in identically oriented positions at transversely spaced points therealong to the previously cut strip located above it. 
     As shown in  FIGS. 16 and 17 , the bands of adhesive B′ B of each strip thus adhere (a) the front margin  127  of the center opaque substrate sheet  19 ″ of each strip to the outer margin  130  of the front sheer substrate sheet  18 ″ of the strip above it, and (b) the outer margin  129  of the rear sheer substrate sheet  20 ″ of the former strip to the rear margin  131  of the center opaque substrate sheet  19 ″ above it.  FIGS. 15A and 15B  are fragmentary views of the portion of the cellular panel  10 ′″ of  FIG. 15 , showing the adhesive connections of the identical multi-substrate strips when the panel is expanded. When the outer margin  129  of the rear sheer substrate sheet  20 ″ of the uppermost strip S 1  and the front margin  127  of the center opaque substrate sheet  19 ″ of the uppermost strip S 1  are fixed in the position they are to assume in the expanded cellular panel  10 ′″, and the rest of the panel  10 ′″ is allowed to drop under the force of gravity, a light controlling panel  10 ′″ is formed comprising horizontally elongated vertically aligned closed tubular cells  12 ′″ as seen in FIG.  15 . The front vertical wall  14 ′″ or side of each cell  12 ′″ is formed by the front sheer substrate sheet  18 ″ of one, of the multi-substrate strips; the rear vertical wall  16 ′″ or side of the cell  12 ′″ is formed by the rear sheer substrate sheet  20 ″ of the multi-substrate strip above it. The bottom horizontal wall  17 ′″ of each cell  12 ′″ is formed by the center opaque substrate sheet  19 ″ of said one strip; and the top horizontal wall  15 ′″ of that cell is formed by the center opaque substrate sheet  19 ′″ of the strip above it. Stated another way, the front and rear substrate sheets  18 ″,  20 ″ of each strip formrespectivelythe front and rear wall portions of adjacent cells. 
     In order to better understand the relationship between the various cut and laterally offset laminated multi-substrate strips S 1 ,S 2 ,S 3 ,S 4  shown in  FIG. 17  that form the expanded panel  10 ′″ in  FIG. 15 , the front substrate sheet of each strip is designated by the letter F, the center opaque substrate sheet of each strip is designated by the letter C and the rear substrate sheet of each strip is designated by the letter R, with the particular substrate sheet of a given strip being further identified by a reference number corresponding to the reference number identifying that strip. Similarly, the forwardmost adhesive band of each strip is identified by the letter B′ and the rearmost adhesive band of each strip identified by the letter B, with the various adhesive bands of the various strips each identified by a number corresponding to the number of the particular strip involved. Thus, the various substrate sheets, adhesive bands of the various strips shown in  FIG. 17  can immediately be identified in FIG.  15 . 
     The adjustment of the panel  10 ′″ to obtain the light passing and obstructing modes of operation is very similar to that of the open tube panel  10 ″ of  FIGS. 11-14 . When the front and rear sheer substrate sheets  18 ″, 20 ″ of the multi-substrate strips S 1 ,S 2 , etc. making up panel  10 ′″ are shifted vertically relative to one another from their positions shown in  FIG. 15 , the center opaque substrate sheets  19 ″ of the various strips of the cellular panel  10 ′″ are pivoted from horizontal light-passing positions to upstanding light-blocking positions. Because the center opaque substrate sheets  19 ″ are wider than the outer sheer substrate sheets  18 ″, 20 ″, the center opaque substrate sheets  19 ″ overlap one another in their light-blocking upstanding positions, thus preventing any light from passing through the cellular panel  10 ′″. 
       FIG. 18  is a block diagram showing the different steps of manufacturing the cellular panel  10 ′″ of FIG.  15 . The laminated multi-substrate strips forming a web  30 ″ are unwound from a driven supply reel  128 ″ and pass through tension control and web aligning means  41 ′. Adhesive bands B and B′ are applied by adhesive applying means  43 ′ to the multi-substrate web  30 ″ and then the web  30 ″ is cut by cutting means  45  into strips S 1 ,S 2 ,S 3 , etc. The multi-substrate strips are then carried by high speed conveyor means  47 , like that previously described to the raisable conveyer portion  47   b . When the first strip S 1  is laminated, the lifter means  51 ′ raises the raisable conveyor portion to where the first strip S 1  is laminated against a leader strip (not shown) carried by an overhead laterally indexable conveyor belt. After the first strip S 1  is laminated, the second strip S 2  is laminated to the first strip in the pattern described with respect to  FIG. 17 , and the process continues with the third strip S 3 , etc. The control means  53 ′ control the operating sequence of the stations of the production line just described. 
       FIG. 19  shows part of the manufacturing apparatus for making the light controlling closed tube cellular panel  10 ′″ of FIG.  15 . After the multi-substrate web  30 ″ is cut into strips S 1 ,S 2 ,S 3 , etc., adhesive bands B and B′ are applied at the proper longitudinal margins as previously described. A conveyor belt  150 , represented by the stationary conveyor block  47   a  in  FIG. 18 , receives the multi-substrate strips S 1 , S 2 , etc. The conveyor belt  150  is provided with suction holes communicating with a vacuum source (not show) to hold the strips thereon. The conveyor belt  150  conveys the strips to the raisable conveyor belt  151 , represented by block  47   b  in FIG.  18 . The raisable conveyor belt  151  also has suction holes  156  to allow a vacuum box  154 , shown in  FIG. 19 , to hold the multi-substrate strips in place. To begin forming the cellular panel  10 ′″, the first multi-substrate strip is laminated to a leader strip located on a laterally indexable conveyor belt  160 . When the first multi-substrate strip S 1  is then properly positioned, the raisable conveyor  151  delivers the strip S 1  to the overhead laterally indexable conveyor belt  160 , represented by block  49 ′ in FIG.  18 . 
     The laterally indexable conveyor belt  160  also has suction holes  151 ′ communicating with a vacuum box  164  to hold in place the first multi-substrate strip S 1  adhered thereto. When the raisable conveyer belt  151  carrying the second multi-substrate strip stops S 2 , strip location sensors (not shown) in the conveyer belt structure  152  relay the location of the second multi-substrate strip S 2  to the control means  53 ′ in FIG.  18 . The control means  53 ′ then indexes the laterally indexable conveyer belt  160  in the direction shown by the arrows in  FIG. 19  to the proper location where it stops to receive the second multi-substrate strip S 2  delivered thereto. The raisable conveyer belt  151  is part of a structure connected to hydraulically operated portions  155 ′ of hydraulic cylinder  155  which then move the belt  151  upward to laminate the second substrate strip S 2  on raisable conveyer belt  151  against the first multi-substrate strip S 1  above it. This process continues with the subsequent strips. The belt  151  is then lowered by the pistons  155 ′. The sticking force of the adhesive bands B and B′ not yet fully cured, is desirably greater than the vacuum force holding the strip on the belt. If not, vacuum pressure on the belt  151 ′ is momentarily cut-off. 
     As this process continues, the laminated multi-substrate strips now forming a continuous web of laminated strips pass between the laterally indexable belt  160  and a nip roller  170 . The continuous web then passes over an idler roller  172 , under a dancer tensioning roller  174 , which tensions the newly formed web, and over another idler roller  176  to a driven take-up reel  178 . The speed of rewind reel  178  is controlled by the elevation of the dancer tensioning roller  174 . 
     While the invention has been described with reference to preferred embodiments of the invention, it will be understood by those skilled in the art that various changes and modifications may be made and equivalents may be substituted for elements thereof without departing from the broader aspects of the invention.