Abstract:
In the methods described, a treatment method is employed on a flexible substrate forming a multi-layer array. The method includes providing the flexible substrate; placing a material to be treated on a surface of the flexible substrate; and treating the material with a frequency energy.

Description:
TECHNICAL FIELD  
       [0001]     Described herein is a method for treating material, more particularly, for treating multi-layer arrays.  
       BACKGROUND  
       [0002]     One type of multi-layer array is an expandable honeycomb insulation panel or cellular window array made from a plurality of strips or folded stacked sheets of flexible fabric or film and bonded between adjacent layers along parallel lines to form an expandable cellular structure.  
         [0003]     The fabrication of expandable honeycomb insulation panels entails a continuous process of manipulating a continuous length of thin plastic film to form uniform, clean-cut, neat, and effective insulation panels. This includes the steps of continuously creasing and folding the thin plastic film into an open-sided tubular structure, heat-setting the folds against a surface and under constant tension in a uniform manner to eliminate internal stresses that could otherwise cause warps or wrinkles, applying continuous adhesive material to the surface of the open sided tubular structure, and continuously stacking the tubular film in layers on a flat surface or a plurality of flat surfaces to eliminate any curves that might cause wrinkles or warps in the finished product.  
         [0004]     An apparatus for fabricating the expandable honeycomb insulation material described above includes an initial creaser assembly in which a pair of spaced-apart sharp wheels are pressed into the film to form uniformed creases in the film material. It also includes a folding assembly to fold the lateral edges at the crease over the mid-portion thereof, and a press assembly to mechanically crimp the folds. The apparatus also includes a heat-setting assembly for heating the plastic film material to a sufficiently high temperature so that it loses its elasticity and becomes sufficiently plastic to permanently set the folds therein. This heat-setting assembly provides a uniform surface around the periphery of a large-diameter heated roller on which the folded film is pressed under constant tension to eliminate internal stresses in the material.  
         [0005]     A drive assembly pulls the plastic film through the folding and heat-setting assemblies, and a positive displacement pump feeds a liquid adhesive through an applicator for deposition onto the surface of the folded tubular plastic film. The pump is driven from the film drive assembly so that the rate of deposition of the adhesive material on the film is always in direct relation to the rate of speed in which the film moves through the apparatus in order to maintain uniform beads of adhesive for glue lines in the finished panel product. The apparatus also includes a rotatable stacking bed with flat surfaces on which successive lengths of tubular film are stacked in uniform layers, one on another, where they are adhered together to form the panel structures, and a tension and speed control assembly for maintaining a constant tension of the film as it is stacked uniformly in layers on the rotating stacking bed.  
         [0006]     This process is time-consuming and expensive requiring application of adhesive lines before stacking, followed by bulk treatment of the stack to activate and cure the adhesive. While faster than prior art methods, this process requires containment of large stacks of material for curing, done thermally by heating the entire stack and its containment. Specifically, this step consumes excessive energy and time, and includes a risk of thermal distortion in the heating of the stack. Therefore, there is a need for a faster, less thermally intense method of curing pre-applied adhesives within the stack. Such a method is broadly applicable to numerous layered products, such as quilts, carpets, insulation goods, heat exchangers, and the like where complex patterns of bonding are required within the bulk of a built-up assemblage of layers.  
       SUMMARY  
       [0007]     As described below, a treatment method is employed on a flexible substrate forming a multi-layer array. The method includes providing the flexible substrate; placing a material to be treated on a surface of the flexible substrate; and treating the material with a frequency energy.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     The features and inventive aspects of the present invention will become more apparent from the following detailed description, the appended claims, and the accompanying drawings, of which the following is a brief description:  
         [0009]      FIG. 1  is a cross-sectional illustration of an exemplary embodiment of a folded multi-layer array showing enlarged circular bonding lines for clarity;  
         [0010]      FIG. 2  is a cross-sectional illustration of the array of  FIG. 1  in an expanded orientation showing enlarged circular bonding lines for clarity;  
         [0011]      FIG. 3  is a perspective view of a material forming the array of  FIG. 1 , showing a pattern of coatings;  
         [0012]      FIG. 4  is a side elevation of the material of  FIG. 3  showing the pattern of coatings in greater detail;  
         [0013]      FIG. 5  is an exemplary schematic of a machinery layout;  
         [0014]      FIG. 6  is an end elevational view, partially sectional, of a roller-type pleater employed in the machinery layout of  FIG. 5 ;  
         [0015]      FIG. 7  is a sectional schematic representation of a folding station employed in the machinery of layout of  FIG. 5 ; and  
         [0016]      FIG. 8  is a schematic representation of a radio-frequency press. 
     
    
     DETAILED DESCRIPTION  
       [0017]     Referring now to the drawings, illustrative embodiments are shown in detail. Although the drawings represent the embodiments, the drawings are not necessarily to scale and certain features may be exaggerated to better illustrate and explain an innovative aspect of an embodiment. Further, the embodiments described herein are not intended to be exhaustive or otherwise limit or restrict the invention to the precise form and configuration shown in the drawings and disclosed in the following detailed description.  
         [0018]     Referring now to  FIGS. 1 and 2 , an exemplary embodiment of a cellular array  20  (also referred to as a cellular shade) is illustrated in a collapsed and expanded position. For the purposes of lending brevity and clarity to the disclosure,  FIGS. 1 and 2  are illustrated having a material forming ligaments between bonding lines  24  in the structure of the cellular array  20 . It should be understood that the bonding lines  24  are typically a thin film between the material folds forming the ligaments  22 . However, for the purpose of clarity, the bonding lines  24  are represented as circular in form. The ligaments  22  may be any portion of the cellular array  20 , folded or unfolded. Specifically, the ligaments  22  are parts of the cellular array  20  appearing between bonding lines  24  and folds  28 . A bonding line  24  includes any portion of the cellular array  20  that has glue or adhesive, whether fully or partially cured, applied thereto. The bond line  24  results when an adhesive adheres to another adhesive or any other portion of the cellular array  20 . The term “line” is used simply because, to the untrained eye, the adhesive appears to be nothing more than a (barely) discernible line of a coating material. But, it is the character of appropriate adhesives to stiffen when fully cured and thereby impart to the cellular array  20  an integral, transverse structural element.  
         [0019]     The cellular array  20  is formed from a continuous material having an adhesive applied between each predetermined index  26  for a fold  28 , generally closer to the open side  30  of the proposed fold  28  than to the closed side proximate the fold  28 . In appearance, the bonding line  24  straddles a crease or fold  28 . Each bonding line  24  is generally equidistant from the fold  28  and on the surface of the cellular array  20  that will be exposed to view.  
         [0020]     In  FIG. 2 , the flexibility of the cellular array  20  material and the functioning of folds  28  as permanent hinge lines permit the tubular ligaments  22  to be readily and non-destructively collapsed and expanded along an axis A-A parallel to the length of the original cellular array  20  as the cellular array  20  is raised and lowered, respectively, during use. The ligaments  22  are parts of the cellular array  20  appearing between bonding lines  24  and folds  28 ; and internal ligaments  32  are portions of the cellular array  20  appearing between the bonding lines  24 . When the resulting structure is expanded, as in  FIG. 2 , a continuous array of enclosed tubular cells is formed. If the bonding lines  24  are located such that the ligaments  22  are generally shorter than the internal ligaments  32 , then the cellular array  20  will reach its full extension with the ligaments  22  approaching a generally parallel relationship with one another, without excessive twisting of internal ligaments  32 . The outer faces; that is, the back and front of the cellular array  20 , are for all intents and purposes generally identical. The viewer observes only a pleated array, aesthetically pleasing to the eye.  
         [0021]     The exemplary embodiment illustrated in  FIGS. 1 and 2  permits the inclusion of actuating and guiding mechanisms (not shown) in the space between the bonding lines  24 . The internal ligaments  32  may be pierced, slotted, or truncated (that is, the transverse length of the internal ligaments  32 , relative to the ligaments  22 , is shortened) in order to provide for any of known actuating and guiding mechanisms, without danger of binding the mechanisms.  
         [0022]     For purposes of illustration,  FIG. 3  is highly stylized in that the material  40  forming the cellular array  20  is shown with an imprinted pattern of coatings, and the adhesive bonding lines  24  are denoted by strips  42 . The material  40  passes over a roller  46  and is displayed narrower than it would actually be. The material  40  is printed on an upper surface  48  and a lower surface  50  and the adhesive strips  42  that appear in  FIG. 3  are alternatingly placed with adhesive strips  42  that appear on the lower surface  50 .  
         [0023]      FIG. 4  is a side elevation of the material  40  and presents the coating scheme of  FIG. 3  in cross-section. The large barbed arrowheads denote the points of fold as they appear in their alternating pattern. As the material  40  is folded, in the direction of the bold arrowhead, the ligaments  22 , as indicated herein, become the webbing portions that are located between the folds  28  and its adjacent strips  42  of  FIG. 2 . Discernible in  FIG. 4  is the resulting internal ligament  32 , and the webbing between adjacent adhesive strips, herein  42 . This coating and folding pattern realizes the structure disclosed in  FIGS. 1 and 2 .  
         [0024]     The manufacture of the exemplary embodiments of the cellular array  20  is accomplished through an amalgamation of techniques and machinery such as screen printers, phasing control electronics, and adhesive curing apparatus. Tying all of the apparatus together to realize the described embodiment is an exemplary process that begins with a single continuous material  40  as described above, (fabric web  311  and folded fabric web  311 ′ for the purpose of the manufacturing description) and results in a completed product that is only then separated from the continuous web  311  for final curing. Illustrative of the machinery and process used to acquire the described embodiment is  FIG. 5 , a schematic drawing of the production line  300 . The process begins with an unrolling of the web  311  from the supply reel  302 . The web  311  is passed through a tensioner station  304 , the function of which is to maintain proper tautness in the web  311  throughout the first process to be performed thereon.  
         [0025]     After passing through the tensioner  304  the web  311  passes through the first screen printing station  306 , between the drip trays  305  and the print rollers  307  thereof. The screen printer, like the source roller and tensioner  304 , includes existing machinery and has as its primary function the ability to print and/or coat the web  311 , both top and bottom, with various desired colors, patterns or coatings, of adhesive. These other coatings, addressed in  FIGS. 3 and 4 , may include colorings, texturings or myriad forms of reflective or insulative coatings.  
         [0026]     In keeping with the type of coatings thus applied at the first screen printing station  306 , the next station to be encountered by the newly coated web  311  is the first curing station  320 . This station renders a full curing to the coatings previously applied, i.e. to fully “dry” the coatings and thereby reduce porosity of the web  311 . At this point, the web  311  has been coated, on both sides, with preselected coatings at predetermined locations. It should be noted that multiple stations that apply coatings to only one side per station, but are otherwise similar to the two-sided coaters described herein may be used if desired.  
         [0027]     Passing out of the first drying station, the web  311  moves to a registry detection station  330 , the function of which is to provide final adjustment in the web  311  travel so that the uncoated spaces, both top and bottom, will be properly aligned for deposition of the adhesive or bonding material.  
         [0028]     Immediately thereafter, the web  311  is passed into the second screen printing station  340  where, like at the first, it passes between drip trays  345  and screen printing rollers  347  to be coated with the predetermined bonding line scheme.  
         [0029]     Subsequently, the web  311 , bearing adhesive applications on both sides, is passed into the second curing station  350 . This station differs from the first in that only a partial cure is effected. Where, at the first curing station a full cure is desired in order to dry the color, reflective and insulative coatings, now only a partial curing to the “gel” state is made. The adhesive remains in a partially cured state until it can be brought into contact with another section of the same web  311  to effect the bond lines.  
         [0030]     After leaving the last curing station  350 , the web  311  is passed downline to the creaser  400 . Immediately before its encounter with the creaser  400 , the web  311  is subjected to final scrutiny by passing it over the phase reader  360 . The reader operates with creaser  400 , causing the diameters of rollers  402  of  FIG. 6  to vary, thus controlling the pitch of the pleats and the phase of the pleats relative to the print pattern.  
         [0031]     After proper phasing relationship is established relative to the adhesive strip (print) placement, the web  311  is introduced to the creaser  400 . There, creases or folds are made in the web  311 , in alternating pattern(s) after the fashions described above and in  FIGS. 3 and 4 .  
         [0032]     Upon exiting the creaser  400 , the alternatingly creased web  311  is passed to the folding machinery  500 ,  600 . The first portion of the folding machinery includes a pair of counter-rotating air knives fixed in set-apart registry and receptive of the creased web  311  between them. The air knife, a device well known in several industries, includes a machine capable of emitting a steady, intense flow of air along a predetermined path. In this instance, both air knives emit this intense flow of air in a straight line, transverse of the web  311 . Since the knives are spaced one from the other and rotate in opposite directions, there is effected between them a shearing wind pattern. As the web  311  passes between the rotating air knives, its presence forms a barrier and, if the rotation and counter-rotation of the air knives  500  are properly phased, the shearing effect of the radially moving planes of air will cause a fold at the creases of the web  311  by intensifying the folds at their troughs. Continuing in the pattern of rotation, the air knives urge the trough (which each respectively fills) towards the direction of movement of web  311 .  
         [0033]     The urging of the folding web  311  is such that it is readily introduced into the second substation of the folding apparatus, the batcher  600 . The batcher  600  is an essentially elongated rectangular confinement which is adapted to accept the air knife—advanced web  311  into its interior. The batcher is the second piece of apparatus devised expressly by the instant inventors for the purposes of realizing a uniquely constructed product. It should be readily understood by the reader, indeed those of ordinary skill in the art, that with the folded array adequately gathered into the batcher, there is little left to accomplish save acquiring the final cure to the partially cured adhesive strips to form bond lines. The point at which the pleated fabric enters the batcher  600  in the collapsed state signals accretion (uniting by adhesion) of the desired product and the end of the algorithmic manufacturing process. Depending upon the types of adhesive used, it is conceivable that collection in the batcher could signal termination of the entire process.  
         [0034]     The creaser  400  is illustrated in a partially sectional side elevation at  FIG. 6  as having two roller assemblies  402 . Passing therebetween is the web  311 , having been properly tensioned so that pleats may be made in proper registration with the bond striping. One roller assembly  402 , here the left-hand assembly partially shown, is rigidly mounted by the bolting  404  of its pillow block bearing  406  to the slider block  408  that is rigidly mounted to the pleater pad  410 . The second roller, of  FIG. 6 , the right-hand assembly illustrated, is similarly bolt-mounted  404  to the fixed bearing pillow block  406 . Unlike the first assembly, however, the second roller assembly is bolted to an adjustable slider block  408 ′. The adjustability of slider block  408 ′ derives from the fact that the bolt holes  405  for this assembly are over-sized and allow adjustment mechanism  412  to exert a force on the slider block  408 ′ to adjust the center spacing between the two cylindrical roller assemblies  402 . An air pressure supply line  414  is seen entering the roller assembly at the pillow block central thereto and axial of the roller assembly  415 . The last outwardly visible elements of the roller assembly are the crease ridges  416 . The crease ridges are essentially inverted “V” shaped protrusions which run the length of the roller and are bolted or riveted  418  to the outer periphery of the roller assembly  402 .  
         [0035]     In the cut-away portion of  FIG. 6 , disposed on the right hand pleater roller subassembly  406  is a tri-part, concentric, cylinder roller structure. Moving from the axial center outward, the structure includes a first or inner rigid, foraminous cylinder that is rigidly fixed to the cylinder end plate  423  and rotatable therewith on the cylinder bearing. Next, an intermediate cylinder includes a bladder likewise sealed to the cylinder end plates  423  in spaced-apart registry from the foraminous inner cylinder. It rotates with the inner foraminous cylinder. One will now recognize the cooperative relationship between the air pressure supply  414  passing through the sealed bearings  415  into the perforated chamber formed by inner cylinder  420  and bounded sealably by the second cylinder (bladder)  422  as effecting an air-controllable cylindrical surface that may be caused to expand and contract, thereby effecting a slight change in diameter of outer cylinder  424 , which adjusts the crease pitch relative to the bond lines. The outermost cylinder  424  comprises a resilient shell in contact registry with the intermediate cylinder  422 , but not attached to the rotating cylinder end plate  423  that couples inner cylinder  420  with bladder cylinder  422 . The outer cylinder is composed of a resilient material responsive to the flexing of intermediate cylinder  422 , but formed of such a material that it will remain inactive and nonadhesive to the partially cured bonding material which it will contact, such as silicone rubber.  
         [0036]     Final to this illustration is the apparatus which effects not only the fixing of the crease ridges  416  to the outer cylinder  424 , but also couples the outer cylinder to the foraminous inner cylinder  420 . The crease ridge includes rivets  418  and a torque coupling pin  426 . The rivets pass through the outer flanges of the crease ridges  416  as shown in  FIG. 8  and down through the outer and intermediate cylinders. Captured therebetween is the cap  427  of torque coupling pin  426 . The torque coupling pin is freely slidable in selected foramens  421  of the inner cylinder  420 . Cap  427  provides a seal that prevents air leakage from bladder cylinder  422 . Thus, the coupling pin assembly couples the rotation of inner cylinder  420  to the outer cylinder  424  and, because of its slidability in foramen  421 , allows the expansion and contraction of the outermost cylinder  424  as the intermediate cylinder-bladder  422  is caused to flex by the introduction or evacuation of air through supply line  414 . If the phasing or pitch of creases between adhesive strips is improper, air is forced into or evacuated from bladder  422  causing it to expand or contract, thus adjusting to the proper crease pitch and phase (registry).  
         [0037]     In the pleating operation, the web  311  to be pleated is introduced between the rollers which are moving in the direction indicated by the barbed arrows. As the properly phased crease ridge  416  comes in contact with the web  311 , it nips it between its crest and the opposing roller, which at that space on its surface is devoid of ridging. The crease ridge  416  presses the web  311  into the resilient surface of the roller, thus effecting the crease in the web  311 ; and the creased web  311 ′ exits between the pleater rollers. Immediately thereafter, as generally described above, the creased web  311 ′ enters the folding station air knife subassembly  500 .  
         [0038]     In a schematic drawing of greater detail,  FIG. 7  portrays the subsequent operations performed on the creased web  311 ′ that has been adhesive coated to acquire the predetermined array configuration. As the creased fabric enters the air knife subassembly  500 , the first rotating knife  504  exerts its continuous stream of air downwardly, enhancing the crease  116  and, rotating counter-clockwise, the first air knife  504 , in conjunction with the second air knife  502  rotating clockwise, urges the fabric, while effecting a more pronounced fold, toward batcher box subassembly  600 . When the air knives  502 ,  504  are in proper phase relationship, they will effect a continuous folding and urging of the creased web  311 ′ toward the mouth  602  of batcher subassembly  600 .  
         [0039]     The mouth receiving portions  602  of batcher box  604  are splayed with a smooth radius so as to receive and guide the now folding web  311 ′ smoothly into the interior of box  604 . Located proximate the periphery of the box  604  proper is an electronic fold sensing network that detects the crest of every pleat passed into the mouth of the box  604 . Sensed data are transmitted to the batcher box fill control (not shown herein). This assures that proper stacking takes place as the web  311 ′ is folded into the batcher box  604  by the action of the air knife subassembly  500 .  
         [0040]     As the folded web  311 ′ enters the batcher box, it encounters first the air pressure motivated base  608 . Also proximate the sensor  606  is a series of peripheral ports  620  which, connected through peripheral chambers  622 , draw off air which has accumulated at the mouth  602  of the batcher box  604 . The air overpressure is drawn off through conduit  624 . Concurrently, as air pressure is being supplied through air supply line  610 , thus urging base  608  outward, data being sensed at sensor  606  (through suitable control means not shown herein) cause the actuation of stepping motor  614  to draw up cable  612 , thus retracting base  608 . Thus, as the count of folds is increased at the electronic sensor  606 , the pressure supported base  608  is drawn toward the bottom of the batcher box  604 , and the ensuing stack of pleated fabric is accomplished orderly and precisely. It can be seen in  FIG. 7  that adhesive strips actually adhere to adhesive strips to form bonding lines. This may not always be the case and partially cured adhesive or bonding material may be placed in contact with portions of the web  311  not bearing adhesive.  
         [0041]     The method of locally bonding the cellular array  20  includes the application of adhesives sensitive to excitation and self-heating or curing under the influence of radio-frequency electromagnetic fields. Further, the selection of a radio frequency, the selection of an adhesive or its components in consideration of the frequency, the apparatus  700  of  FIG. 8 , the method of application of the radio frequency to the product and the resulting product, itself will be described.  
         [0042]     The adhesive is chosen to be thermally curable and to include compounds such as polyester monomers, metal salts, or nylon that readily absorb energy from a radio-frequency field. The frequency is chosen such that the material  40  of the web  311  has significantly less energy absorption than the adhesive.  
         [0043]      FIG. 8  is a sectional schematic of the curing apparatus  700 . The collected stack  701 , in its partially cured stage, has been removed from batcher box  604  and placed into press  702 . The press  702  is as long and as wide as required by the folded web  311 ′ and the pleat width, respectively. The press  702  includes a base  704  and a lid  706  interconnected at a hinge or hinges  708 . A compression ram  710  is disposed at one end of the stack to assure alignment of all pleats and to apply pressure to the stack and its adhesive lines. The stack  701  is placed in the press  702  and compressed therein by a compression ram  710 . Immediately after emplacement, the lid  706  is closed. A securing mechanism (not shown) firmly secures lid  706  to the base  704 . Thereafter, a radio-frequency field is energized by a generator  712 , powered by an electrical input  714 . Application of the resulting radio-frequency electric field by voltages on the conductive electrode platens  716 ,  718  of the curing apparatus  700  heats the adhesive  720  (bonding line  24  of  FIGS. 1 and 2 ) to trigger its activation and curing, thereby bonding adjacent layers wherever adhesive lines are present between them.  
         [0044]     In an exemplary apparatus  700 , the generator  712  is a 25 KW power supply that operates at 17 MHz (ideal for coupling to the adhesive is 27.12 MHz, but field efficiency and stability is enhanced at lower frequencies, and coupling is still adequate). The temperatures of upper electrode  715  and lower electrode  718  are controlled by chilled and heated water to a constant temperature of 65 degrees Fahrenheit. The temperature is raised and lowered with changes in ambient temperature. The power and frequency are continually adjusted to compensate for load changes during curing. The compression ram  710  and the upper electrode  716  pressure is deliverable pneumatically in two stages between 20 and 50 pounds per square inch (PSI).  
         [0045]     In one exemplary process, the pre-folded stack  701  is conveyed into the press  702  and onto the lower electrode  718 . The upper electrode  716  is lowered to a predetermined height in contact with the stack  701 . A portion of the stack  701  is compressed by the pneumatic ram  710 , at which time the RF field is activated at 3.5 amps to preheat the adhesive  720  without forcing the stack  701  out of stacked alignment. After a predetermined time, the adhesive  720  is softened, the stack  701  is substantially compressed, and the RF field is reduced to 2.75 amps to complete the bonding. After a second predetermined period of time, the RF field is terminated and the stack  701  remains under pressure for an additional predetermined cooling period to cool in position, setting the bonds. After the cooling cycle the upper electrode  716  in the lid  706  is raised and the stack  701  is removed from the press  702 .  
         [0046]     One benefit in the above described process is the application to multiple linear adhesive features that are neither ‘parallel’ (i.e, reaching from one electrode to the other) nor ‘perpendicular’ (i.e., presenting a broad flat target normal to the field). In some instances, called ‘stray field’ heating, the glue to be heated cannot be arranged either perpendicularly or parallel. In the described process, however, the adjacent substrate material is not RF-conductive and so experiences little absorption of the RF energy from stray field. The material  40  may be formed from woven fabric, non-woven fabric, polyester, or the like. The described process relies on the uniform placement of discontinuous absorbent zones (adhesive lines  720 ) to produce uniform absorption and heating of those zones. Otherwise, the field stability and heating uniformity becomes unsustainable.  
         [0047]     Another benefit of the described process is the adaptation of an RF press  702  to a flexible substrate. The RF heating of a complex, flexible product is unique and offers advantages over the prior art.  
         [0048]     As will be clear to one skilled in the art, the described embodiments and methods, though having the particular advantages of compactness and convenience, are not the only methods or arrangements contemplated. Some exemplary variants include: a) material to be treated and bonded can be fed through the RF field in a continuous stream, rather than by batches; b) material blocks to be bonded can be fed through a smaller field area, curing from one end to the other sequentially, rather than the whole block at once; and c) any combination of frequencies and materials receptive thereto could be substituted for the chosen RF and adhesives.  
         [0049]     The precise application of activation energy to the adhesive rather than the bulk stack of material has many advantages including: a) reduced total energy usage; b) reduced cycle time without waiting for heating and cooling the bulk material or containments; c) reduced handling of goods by in-line treatment rather than large oven-run batches; d) reduced thermal distortions and discolorations due to uneven heating of stack materials; e) precise and uniform heating of adhesive to assure uniform and complete bonding of adjacent layers without bleed-through to farther layers; f) usability with stack materials that are not amenable to thermal or other adhesive curing cycles in bulk; and g) improved regularity of pleat alignment and glue line positioning by reduced clamping and thermal loads during cure.  
         [0050]     The preceding description has been presented only to illustrate and describe exemplary embodiments of the methods and systems of the present invention. It is not intended to be exhaustive or to limit the invention to any precise form disclosed. It will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. The invention may be practiced otherwise than is specifically explained and illustrated without departing from its spirit or scope. The scope of the invention is limited solely by the following claims.