Abstract:
A machine ( 10 ) and method for the continuous folding of sheet material ( 15 ) into difference three-dimensional patterns is featured. The innovative machine and method folds sheet material by force converging the sheet to a final stage that imparts a final fold or pattern. Unique programming allows for the change of convergence sequencing and change of materials. A plain die fold multiplier is placed before the final stage to double the number of folds in the sheet material and halve the height thereof.

Description:
RELATED PATENT AND APPLICATIONS 
       [0001]    This Application is related to co-pending U.S. application Ser. No. 11/265,571 filed 2 Nov. 2005, and Ser. No. 11/518,642 filed 11 Sep. 2006, and to U.S. Pat. No. 7,115,089, each having the same assignee herewith. Also, this Application takes priority from U.S. application Ser. No. 11/518,642. The teachings of both the co-pending applications and patent are incorporated by reference herein to the extent they do not conflict herewith. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to the folding of sheet materials and, more particularly, to the continuous folding of different types of sheet materials into a multiplicity of predetermined, three-dimensional structural patterns having a desired number of folds and fold heights. 
       BACKGROUND OF THE INVENTION 
       [0003]    Folded materials are useful in packaging technology, sandwich structures, floor boards, car bumpers and other applications where requirements pertaining to shock, vibration, energy absorption, and/or a high strength-to-weight ratio including volume reduction must be met. 
         [0004]    Continuous folding machines should have versatility, flexibility, and high production rates. Additionally, a machine that can additionally accomplish folding in an inexpensive manner is most rare. 
       SUMMARY OF THE INVENTION 
       [0005]    In accordance with the present invention, various inventive embodiments for a machine and method for the continuous folding of sheet material into different three-dimensional patterns is disclosed. 
         [0006]    One objective of the present inventive machine is to provide the folding of a wide range of materials over a range of desired fold configurations, and to fold such material over a wide range of sizes. 
         [0007]    Another objective of the invention is to provide a machine with the ability to fold different types of sheet materials, as opposed to mere metal or paper, thereby providing a cost saving, because users need invest in only one machine. 
         [0008]    Another objective is to provide a machine that can generate patterns with extensive geometric variations within the same family of patterns. The generated patterns can then be used in many applications such as cores for sandwiched structures, pallets, bridge decks, floor decks, and packaging applications. 
         [0009]    The invention accomplishes all of the above objectives by having both a unique structure and unique programming. The programming allows for the change of the folding sequence, so that different patterns can be produced. The programming also allows for a selective change of materials. 
         [0010]    The present inventive machine can also be programmed to provide microfolding stations each of which increases the number of folds while reducing the fold height, whereby if the number of folds are doubled, the fold height is reduced by one-half, for example. 
         [0011]    In a general overview, the inventive machine causes the material to funnel towards an end section, which imparts the final folds or pattern. The funnel process can be thought of as a method of force convergence, or continuous-positioning of the material towards the final stage of the machine. The material is then finally folded in the desired pattern at the final stage. 
         [0012]    The innovative machine folds sheet material, including paper, biodegradable material, composites and plastics, enables a flat sheet of material to be fed through a series of rollers or dies (the number of which is a function of final product width) that pre-fold the material until it reaches the last set of rollers or dies. The final fold pattern is implemented by having the pattern geometry negatively engraved on these rollers. The direction of the engraved folding pattern on the last set of rollers can be made longitudinal or perpendicular to the roller axis (or at any desirable angle in between), resulting in a longitudinal, angular or cross-folded sheet. Further, the last set of rollers can be made from different materials (metals, PVC, . . . ) or combinations of two different materials such as rubber on metal (one roller from rubber and the other from metal to create sharp increases in the folded pattern). 
         [0013]    The material is fed between the first set of rollers or dies, which makes a central single fold in the middle of the material. The material then advances to a second set of rollers or dies, that makes two extra outer folds, one on each side of the first fold. The material then advances to a third set of rollers or dies, making two additional outer folds. This process continues at the sequenced sets of rollers or dies until the desired number of folds in the rolling direction is reached. In one embodiment of the invention a microfold multiplier having a plain (or circular) die configuration is inserted between a last roller or die for providing longitudinal folding and a final cross folding roller, for microfolding the sheet material before it enters the final roller. 
         [0014]    At the last set of rollers or dies, the material is rolled between two rollers or dies having the fold patterns engraved/machined on their surfaces to produce the final pattern of the folded sheet. No additional folds are made at the last set of rollers or dies. The design, manufacture, and integration of the last set of rollers or dies is flexible enough that other patterns can easily be produced in a short period of time and with minimum machine setting of both pre- and final folding stages. The above procedures are applicable to any other method for folding based on the principle of series 1, 3, 5, 7 . . . , until the desired width of material is achieved. At this stage the material is then fed through the fold multiplier die to reduce the height of the pattern by 50% and double the number of folds in the same material width. This includes flat dies or frames (or roller dies) with grooves that follow this sequence. 
         [0015]    The folded sheet, upon leaving the inventive machine, can be compressed further to any desired compaction ratio and/or laminated between overlying and underlying sheets of material to produce structures and packaging material with specific characteristics. The design flexibility of the machine allows folding patterns of different materials and different thicknesses and/or with different mechanical properties. 
         [0016]    Specifically, the invention performs folding in the mathematical series 1, 3, 5, 7, . . . , where the numerals are related to the number of tessellations on the surface of each set of rollers or dies at each stage of the initial folding process. This specific sequencing, creating two new longitudinal tessellations on each successive set of rollers according to the mathematical series 1, 3, 5, 7, . . . totally eliminates the typical material slitting (or shredding) phenomenon, which occurs if all tessellation is performed in one set of rollers or dies, causing material to be cogged in, and stretch to conform to, roll or die profile. This innovative technique eliminates this slitting (or shredding) phenomena by subjecting the sheet material to only two predetermined transverse friction forces: one on each edge of the sheet. Material on the edges has access to flow in from the sides to form the next two extra tessellations without undue restriction. 
         [0017]    The innovative sequential tessellation technique enables sheet materials to be effectively folded with minimum power requirements, and without sheet slitting and/or stretching. The innovative use of one or more microfolding fold multiplier plain dies before a final cross folding roller reduces the length of the machine compared to not using fold multiplier roller stations. 
         [0018]    This technology introduces new and highly economical methods of producing lightweight cores, structures, and packages that outperform most of the existing comparative structures and their methods of production. The material that is formed has many applications ranging from the design of diesel filters, to aviator crash helmets, to high-speed lighters, to airdrop cushioning systems, to biodegradable packaging materials and to lightweight floor decks, among others. The technology can produce structures of versatile shapes, single and multiple layers, and different patterns created from different materials, geometries and dimensions. 
         [0019]    The inventive machine has produced packages that have outperformed honeycomb packages, the current industry and government standard. The produced cushioning packaging pads are capable of absorbing significantly higher energy per unit volume when compared with honeycomb packaging structures. 
         [0020]    All types of 3-D geometrical patterns can be formed from a flat sheet of material without stretching, and then selecting such a pattern to be folded. Specifically, to preserve the folding intrinsic geometry, each vertex in a faceted surface must have all the angles meet at the point from adjacent faces to total 360 degrees. This 360-degree total of angles is required for the vertex to unfold and lay flat in the plane, thereby eliminating stretching. 
         [0021]    A mathematical theory of the folding geometry of this invention was been developed by Daniel Kling, and can be studied in greater detail in U.S. Pat. No. 6,935,997. This theory facilitates the pattern selection process for use with the inventive machine. A pattern can be chosen via this mathematical theory based on different criteria, such as geometry, strength, or density, based on the desired parameters of the final product. 
         [0022]    Other existing technologies for forming sheet materials are not at all similar to the inventive technology. For example, known forming machines use dies of flat and rigid tessellations to stretch the sheet material to form identical shapes to those of the pattern to be produced in the final folded shape of this technology. This technology and other types of technologies result in non-uniform change in both sheet thickness and material properties, due to the nature of the forming operation. This is opposed to the current invention&#39;s folding operation that does not stretch or adversely change any of the existing material physical or mechanical properties since it creates the folded pattern by only bending the sheet material along the edges of the tessellations in the form of plastic hinges. 
         [0023]    An advantage of the present invention is its ability to fold sheet material into a continuous intricate faceted structure. 
         [0024]    Another advantage of the present invention is that it is a versatile, flexible, and inexpensive machine that performs various folding operations. 
         [0025]    Another advantage of the present invention is its ability to fold sheet material while preserving its intrinsic geometry without stretching it. 
         [0026]    Another advantage of the present invention is its ability to fold sheet material with minimum energy and load requirement, due to the nature of the folding mechanism being of very localized deformed zones of plastic hinges formed on tessellation edges. 
         [0027]    Another objective and advantage of the present inventive sheet material folding machine is the use of one or more plain (or roller) die configured fold multipliers to minimize the length and cost of the folding machine. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The present invention is described below with reference to the accompanying drawings, in which like items are identified by the same reference designation, in which: 
           [0029]      FIG. 1  illustrates a top view of the machine of this invention for continuous folding of sheet materials fitted with the fold multiplier; 
           [0030]      FIG. 2  illustrates a side view of the machine for continuous folding of sheet materials fitted with the fold multiplier; 
           [0031]      FIG. 3  illustrates a front view of the machine for continuous folding of sheet materials; 
           [0032]      FIGS. 4A and 4B  show top and bottom sections, respectively, of a plain die configuration, for a folding multiplier for one embodiment of the invention; 
           [0033]      FIG. 5  shows a front elevational view of a the die of  FIGS. 4A and 4B ; 
           [0034]      FIG. 6  shows a back elevational view of the die of  FIGS. 4A and 4B ; 
           [0035]      FIG. 7  is a pictorial view of a portion of a reconfigured bottom die of  FIG. 4B , for illustrating operation of another embodiment of the plain die folding multiplier; 
           [0036]      FIG. 8A  is a top plan view of a top die section of  FIG. 4A ; 
           [0037]      FIG. 8B  is a cross sectional view taken along  8 B- 8 B of  FIG. 8A ; 
           [0038]      FIG. 8C  is a cross sectional view taken along  8 C- 8 C of  FIG. 8A ; 
           [0039]      FIG. 8D  is a left-side view of  FIG. 8A , the right-side view being a mirror image thereof; 
           [0040]      FIG. 9A  is a top plan view of the bottom die section of  FIG. 4B ; 
           [0041]      FIG. 9B  is a cross sectional view taken along  9 B- 9 B of  FIG. 9A ; 
           [0042]      FIG. 9C  is a cross sectional view taken along  9 C- 9 C of  FIG. 9A ; 
           [0043]      FIG. 9D  is a left-side view of  FIG. 9A , the right side view being a mirror image thereof; 
           [0044]      FIG. 10  shows a side view of mating top and bottom die sections of  FIGS. 5 and 6 ; 
           [0045]      FIG. 11  is a front elevational view of the bottom die section of  FIG. 4B ; 
           [0046]      FIG. 12  is a front elevational view of the top die section of  FIG. 4A ; 
           [0047]      FIG. 13  is a back elevational view of the bottom die section of  FIG. 4B ; 
           [0048]      FIG. 14  is a back elevational view of the top die section of  FIG. 4A . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0049]    Generally speaking, a machine for continuous folding of sheet materials is featured. The machine comprises a plurality of rollers or dies, each with a different amount of raised portions (related to the number of tessellations) for creating folds in the material traveling through the machine. 
         [0050]    Now referring to  FIGS. 1 to 3 , the machine for continuous folding of this invention, generally referred to as number  10 , is shown. The machine for continuous folding  10  comprises a plurality of sets of rollers or dies  12 . A set of rollers  12  comprises upper rollers and lower rollers, shown in  FIG. 2 . Each set of rollers, or dies  12  has a number of tessellations  18  for folding sheet material  15 , also shown in  FIG. 3 , where each tessellation is a series of raised shapes (sometimes “V” shaped) that span the circumference of the roller. 
         [0051]    The sheet material  15  is fed through the first proximal set of rollers or dies  16 . Each roller or die  13 ,  14  of the first proximal set of rollers or dies  16  has one tessellation  18 . This tessellation  18  makes a single fold  20  in the sheet material  15 . 
         [0052]    Each roller or die  19 ,  21  of the second set of rollers or dies  22  has three tessellations for making an additional two folds in the sheet material  15 . The single fold  20  produced by the first proximal set of rollers or dies  16  proceeds through the center tessellation of the second set of rollers or dies  22  where it maintains its shape. Two new folds  24 ,  26  are created by the outside tessellations of the second set of rollers or dies  22 . 
         [0053]    Each roller or die  23 ,  25  of the third set of rollers or dies  28  has five tessellations, two more tessellations  18  than each roller or die  19 ,  21  in the previous second set of rollers or dies  22 . This pattern of two additional tessellations  18  per roller or die continues from the first set of rollers or dies  16  to the penultimate set of rollers or dies, shown in this embodiment at numeral  30 . In this example, a plain die  50  configured for multiplying the number of folds from the set of rollers  30  by a factor of two, and reducing the height of the folds by one-half in this example, is installed between the two sets of rollers  30  and  32 . As will be described in greater detail below, the plain die includes an upper plate  52 , and a lower plate  54 . Each roller or die  36 ,  38  of the final set of rollers or dies  32  has the same number of tessellations  18  as the number of folds in the sheet material exiting from the plain die  50 , in this example. The final fold pattern  34  is implemented by having the pattern geometry negatively engraved on the last set of rollers or dies  32 . Further, the last set of rollers or dies  32  can be made of rubber to create sharp creases in the sheet material  15 . 
         [0054]    Six sets of rollers and one plain die are depicted in  FIG. 1 , but the inventive machine for continuous folding  10  can have any number of sets of rollers or dies depending on the desired width and height of the final folded structure. The number of tessellations  18  on each roller or die is determined from the mathematical series 1, 3, 5, 7, . . . , where each roller or die  13 ,  14  in the first proximal set of rollers or dies  16  has one tessellation  18 , and each roller or die  19 ,  21  in the second set of rollers or dies  22  has three tessellations  18 , etc. However, through use of a plain die  50 , as configured in this example for doubling the number of folds while reducing the height of the folds in half, is not meant to be limiting. 
         [0055]    The final material  34  is in the desired form once it leaves the last set of rollers or dies  32 . To fold a different pattern on the sheet material  15 , the tessellations  18  on all of the rollers or dies can be easily changed. 
         [0056]    The design of the machine for continuous folding  10  allows any length of material to be folded. The sheet material  15  starts out at its widest width at the first set of rollers or dies  16  and becomes narrower at each successive set of rollers or dies, as the number of tessellations  18  increases ( FIG. 1 ). This design allows for any length of material to be folded without incurring damage (e.g., stretching) to the sheet material  15 . 
         [0057]    The present inventors recognized that prior art folding machines utilizing a large number of folding rollers are excessively long, and many times are impractical for use, in applications where a large number of folds are required in the sheet material. In many such instances, the length of the machine required for providing a large number of folds is excessive. Accordingly, the present inventors conceived a fold multiplier  50  provided by a plain die configuration  52 ,  54 , as shown in the example in  FIGS. 4A ,  4 B,  5 ,  6 ,  8 A,  8 B,  8 C,  8 D,  9 A,  9 B,  9 C,  9 D, and  11  through  14 , which is described in detail below, whereby the plain die configuration provides for reducing the length of the folding machines while greatly increasing the number of folds in the sheet material, as opposed to using sets of rollers for accomplishing the same number of folds. In the plain die configuration  52 ,  54  example given below, the number of folds are doubled. However, the configuration of the plain die  50  can be modified to provide less than or greater than a doubling of the number of folds. Also, a plurality of plain die configurations can be utilized to increase the number of folds in the sheet material to a desired amount. The inventors expect that the fold multiplier provided by their inventive plain die configuration  52 ,  54  should be able to reduce the length of folding machines in which the dies are utilized according to the mathematical series: ½, ¼, ⅛, 1/16 . . . depending on the final height of the fold when compared with the initial height. For example, in a particular folding machine a one inch high fold is provided from the last set of fold rollers, a die configuration  52 ,  54  of the embodiment of the invention described below is utilized, after passing through the die  50 , the number of folds of the material will be doubled, while the height of the folds will be reduced to ½ inch high. In such an instance, the associated folding machine will likely be reduced in length by a factor of ½, whereas if dies are utilized for quadrupling the number of folds while reducing the fold height from 1 inch to ¼ inch, it is expected that the folding machine length will be ¼ th  that of such a machine utilizing additional rollers for obtaining the same number of folds and fold height. 
         [0058]    An example of a configuration for the die  50  shown in  FIGS. 1 and 2  will now be described. As shown in  FIG. 2 , the die  50  includes a top section  52 , and a bottom section  54  between which the sheet material passes, for doubling the number of folds and decreasing the fold height by a factor of one-half, in this example.  FIG. 4A  shows a pictorial view of a working surface of the top section  52  of die  50 . As shown, the die includes opposing mounting sides  59 , each of which includes mounting holes  51  and  53 , as shown. Between the side portions  59  and from the front of die section  52 , a plurality of parallel and successive triangular projections  56  are formed. Receding from about one third of the way from the front to the back surface of the die section  52 , the triangular projections  56  from triangular shaped grooves  58  cut into respective central portions as shown, with the triangular portions of the grooves  58  having diverging side portions that merge into parallel side portions proximate the top section  52  of the die  50 . The bottom die section  54  of die  50  is shown in  FIG. 4B . Bottom die section  54  includes opposing side mounting portions  57  each having mounting holes  53  and  55 , as shown. Between these mounting sections or portions  57 , the interior face of section  54  is configured to include beginning from a front portion thereof a plurality of triangular-shaped projections  60  each for a short distance have parallel side portions that flow into centrally located converging side portions, followed by parallel side portions for triangular projections  62  that terminate at the back of the die section  54 , as shown. Note that both the top die section  52  and bottom die section  54  each consist of a single piece of material, such as for example Teflon®, PVC, or highly polished aluminum. Other suitable materials with a low coefficient of friction can be used. The top die section  52  is mated with the bottom die section  54 , triangular groove sections  58  formed between the successive triangular projections  56  of the top die section  52  receive the triangular projections  60  of the bottom die section  54 . Also, the successive spaced-apart triangular grooves  58  of the die section  52  receive the triangular projections  62  of the lower die section  54 , in this example.  FIG. 5  shows a front elevational view of the die section  54  mounted upon the bottom die section  54 . Similarly,  FIG. 6  shows the back elevational view of the top die section  52  mounted on the bottom die section  54 . In this example, the sheet material enters the end of the die  50  with eleven and one-half folds, and exits from the back of the die  50  with 23 folds or double the number of folds, but with half the height of the initial folds. 
         [0059]    The configuration of the triangular projections  56 ,  62  and grooves  58 ,  61  in the top die section  52  and bottom die section  54  respectively, actually can be made somewhat more complicated than previously described. Specifically,  FIG. 7  shows a detailed pictorial view of the triangular grooves and projections for a portion of a reconfigured bottom die section referenced as  84 , beginning initially from the front thereof, and proceeding toward the back end thereof, initially a plurality of successive and parallel triangular projections  80  are encountered. About a fourth of the way proceeding from the front to the back end of the die section  84 , the triangular groove  70  with diverging side portions formed there into about the center of the associated triangular projection  80 . Triangular groove  70  is followed by continuing triangular groove  72  that has converging side portions are terminated by one quarter of the distance to the back end of the die section  84 , leading to a fold of ¼ the initial height. Triangular relatively smaller groove sections  74  and  76  each have diverging side portions that are formed immediately adjacent to the right and left hand converging side portions of the triangular groove  72 , respectively, as shown. The triangular grooves  72 ,  74 , and  76 , each terminate about one quarter of the way from the back end of the lower die section  84 , in a manner forming the successive juxtaposed and parallel triangular projections  82 , as previously described. Similarly, the mating top die section (not shown) includes appropriately configured triangular grooves for receiving the triangular projections  60 , and triangular projections  62 . Also, the top die section (not shown) also includes appropriately configured triangular projections that are received by the triangular grooves  70 ,  72 ,  74 , and  76  of lower die section  54 . 
         [0060]    The operation of the plain die folding multiplier  50  will now be described with reference to  FIGS. 4A and 4B . First, assume that the sheet material  15  has passed through the plurality of sets of rollers  12 , and folded using the arithmetic series: 1, 3, 5, 7, . . . until a minimum acceptable fold height of a number of folds has been produced. In this example, the longitudinal folded material  15  is then fed through the fold multiplier  50 . The sheet material  15  exits from the fold die  50  with twice as many folds, with each fold having half the initial height that it previously had when entering the plain die  50 . Note that a plurality of successive plain dies  50  can be installed in the machine  10 , in this example, for repeating the doubling of the number of folds and halving of the fold height until a desired fold height is achieved, for example. 
         [0061]    With further reference to  FIG. 7 , an example of operation of the plain die folding multiplier  50  for another embodiment of the invention will be immediately described. Assume that the plurality of the sets of rollers  12  of folding machine  10  are used to fold the sheet material to a height of 0.5 inch in the longitudinal direction. The sheet material  15  next enters the plain die fold multiplier  50 , the top edges of the folded sheet  15  are forced to deflect downward at point A, thereby forming two triangular segments ABC, and ADC, respectively, which results in reducing the fold height by ½ while the number of folds is doubled. As the sheet material  15  advances from die  50 , the points B and D present the lower apexes, in this example, leaving the sheet material  15  to be forced again to be downwardly deflected to form two new sets of two triangular segments BEF, BGF, respectively, fanning from apex B. Another set of triangles DHJ, DKJ, respectively, are formed fanning from apex D. The entering fold at apex B and apex D is again being reduced to half its height and transformed into two identical smaller folds. The aforesaid process can be repeated as required to obtain a desired final fold height and/or a specific number of folds per inch in the sheet material  15 . Theoretically, there is no limit on the number of stages in the aforesaid fold multiplier process, and the actual limit is set by the combined effect of the coefficient of friction between the sheet material and the die material and sheet material properties. 
         [0062]    With reference to the example of the fold multiplier plain die  50  of  FIGS. 4A and 4B , it utilizes the configuration used for the top section  52 , and bottom die section  54 , for doubling the number of folds and reducing the height by one half for sheet material  15  passed therethrough in an engineering prototype. The fold multiplier plain die configuration of  FIG. 7  is more complicated than that of  FIGS. 4A and 4B , in that three stages of double folding and halving of height are provided. 
         [0063]    The fold multiplier plain die  50  of  FIGS. 4A ,  4 B,  5 , and  6  were used by the inventors in an engineering prototype for doubling the number of folds from a sheet material  15  while reducing the height of the fold in half.  FIGS. 8A through 14  show further details of the plain die multiplier  50  used in an engineering prototype. 
         [0064]      FIGS. 8A and 9A  show the top die section  52 , and bottom die section  54 , respectively, as previously described. Note that the dimensions thereof can be varied for providing a die  50  to receive fold material having folds of a particular height. Also, the length of the die section  52  and  54  can be varied to accommodate a given number of folds of the sheet material to be processed by the die  50 . 
         [0065]    Although various embodiments of the present invention are shown and described, they are not meant to be limiting. Accordingly, the present disclosure covers all changes and modifications that would be apparent to one of skill in the art which do not constitute departures from the true spirit and scope of this invention, and appended claims.