Abstract:
A machine and method for the continuous folding of sheet material into different three-dimensional patterns. The innovative machine and method folds sheet material by force converging the sheet to a final stage that imparts a final fold or pattern into the sheet material, the patterns selectively including one of a Chevron pattern, a honeycomb-like pattern, a double-sided inclined folded core structure, and singular inclined direction folded core structure sheet material.

Description:
RELATED APPLICATIONS 
   This Application claims priority from U.S. Provisional Application Nos. 60/448,896 and 60/448,884 each filed on Feb. 24, 2003. This application is a Continuation-In-Part from Non-Provisional application Ser. No. 11/265,571 filed on Nov. 2, 2005, the latter being a Continuation from Non-Provisional application Ser. No. 10/755,334 filed on Jan. 13, 2004 now U.S. Pat. No. 7,115,089. The teachings of all the aforesaid related Applications are incorporated herein to the extent they do not conflict herewith. 

   FIELD OF THE INVENTION 
   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. 
   BACKGROUND OF THE INVENTION 
   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. 
   Continuous folding machines should have versatility, flexibility, and high production rates. Additionally, a machine that can accomplish folding in an inexpensive manner is most rare. 
   The present inventive machine not only accomplishes the folding of materials in accordance with the aforementioned objectives, but is unique in its ability to fold materials over a wide range of sizes. The machine is also unusual, in that it can handle a wider range of materials. 
   A machine with the ability to fold different types of sheet materials, as opposed to mere metal, provides a cost saving, because users need invest in only one machine. 
   A single machine that can fold many different patterns and which can accommodate different materials demonstrates the flexibility of the current invention. 
   The inventive machine 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. 
   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 that forces, converges, or continuously positions the material towards the final section of the machine, where the material is then finally folded in the desired pattern. 
   DISCUSSION OF RELATED ART 
   U.S. Pat. No. 3,988,917, issued to Petro Mykolenko on Nov. 2, 1976 for Apparatus and Method for Making A Chevron Matrix Strip; U.S. Pat. No. 4,012,932, issued to Lucien Gewiss on Mar. 22, 1977 for Machine for Manufacturing Herringbone-Pleated Structures; U.S. Pat. No. 5,028,474, issued to Ronald Czaplicki on Jul. 2, 1991 for Cellular Core Structure Providing Gridlike Bearing Surfaces on Opposing Parallel Planes of the Formed Core; U.S. Pat. No. 5,947,885, issued to James Paterson on Sep. 7, 1999 for Method and Apparatus for Folding Sheet Materials with Tessellated Patterns; and U.S. Pat. No. 5,983,692, issued to Rolf Brück on Nov. 16, 1999 for Process and Apparatus for Producing a Metal Sheet with a Corrugation Configuration and a Microstructure Disposed Transversely with Respect Thereto; and European Patent Publication Nos. 0 318 497 B1, issued to Nils Höglund on Nov. 27, 1991 for Machine for Corrugating Sheet Metal or the Like; and 0 261 140 B1, issued to Nilsen et al. on Jul. 1, 1992 for Machine for Adjustable Longitudinal Corrugating of Sheet Materials, all relate to the art of forming sheet material. However, none of these patents or publications discloses a machine that performs a folding operation using tessellations according to the mathematical series 1, 3, 5, 7, . . . on each roller in a series of rollers or grooves on parallel flat dies or surfaces. Also, the prior art does not teach other embodiments of the invention as described and claimed below. 
   SUMMARY OF THE INVENTION 
   In accordance with the present invention, a machine and method for the continuous folding of sheet material into different three-dimensional patterns is disclosed. 
   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. 
   The invention accomplishes all these functions 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 change of material and a change of material size. The programming is the subject of a U.S. Pat. No. 6,935,997, issued on Aug. 30, 2005, the teachings of which are incorporated herein by way of reference to the extent they do not conflict herewith. 
   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. Note that in a preferred embodiment, the rollers are heated to allow plastic material to be folded. 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 or cross-folded sheet. Further, the last set of rollers can be rubber on metal (one roller from rubber and the other from metal to create sharp creases in the folded pattern. 
   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. 
   At the last set of rollers or dies, the material is rolled between two rollers or dies having cross fold or same directional fold patterns engraved/machined on their surfaces to produce the final pattern. 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, . . . . This includes flat dies or frames with grooves that follow this sequence. 
   The folded sheet, upon leaving the inventive machine, can be compressed further to any desired compaction ratio and/or laminated 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. 
   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 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 phenomena by subjecting the sheet material to only two predetermined transverse friction forces: one on each edge of the sheet. Material on the edges have access to flow in from the sides to form the next two extra tessellations without undue restriction. 
   The innovative sequential tessellation technique enables sheet materials to be effectively folded with minimum power requirements, and without sheet slitting and/or stretching. 
   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. 
   The inventive machine has produced packages that have outperformed prior 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. 
   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. 
   A mathematical theory of the folding geometry of this invention 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. 
   Other existing technologies for folding sheet materials are not at all similar to the inventive technology. For example, the above-referenced PATERSON patent consists of flat and rigid tessellations that are identical to those of the pattern to be produced in the final folded shape. This technology and other types of technologies result in non-uniform changes 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. 
   An advantage of the present invention is its ability to fold sheet material into a continuous intricate faceted structure. 
   Another advantage of the present invention is that it is a versatile, flexible, and inexpensive machine that performs various folding operations. 
   Another advantage of the present invention is its ability to fold sheet material while preserving its intrinsic geometry without stretching it. 
   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. 
   Another advantage of the present invention is its ability to fold sheet material into a mating surfaces pattern such as a honeycomb structure, for example. 
   Another advantage of the present invention is its ability to fold sheet material into patterns having folded structures with heights of less than 0.25 inch. 
   Another advantage of the present invention is its ability to fold sheet material into a double sided inclined folded core structure. 
   Another advantage of the present invention is its ability to split a double sided inclined folded core structured material into two singular inclined direction folded and core structured strips of material. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is described in detail below with reference to the accompanying drawings, in which like items are identified by the same reference designation, wherein: 
       FIG. 1  illustrates a top plan view of the machine of this invention for continuous folding of sheet materials; 
       FIG. 2  illustrates a side elevational view of the machine for continuous folding of sheet materials; 
       FIG. 3  illustrates a front pictorial view of the machine for continuous folding of sheet materials; and 
       FIG. 4  illustrates a pictorial view of the last set of rollers of the machine for continuous folding of sheet materials into a Chevron pattern. 
       FIG. 5  is a back pictorial view of the machine configured for producing a mating surfaces (MS) pattern in sheet material. 
       FIG. 6A  is a front pictorial view of a set of rollers used for producing an MS pattern in sheet material. 
       FIG. 6B  is a pictorial view of the geometry of one cleat pattern engraved on the rollers of  FIGS. 5 and 6A . 
       FIG. 7  is a pictorial view of a section of sheet material folded into an MS pattern with mating surfaces highlighted. 
       FIG. 8  is a pictorial view of a machine of an embodiment of the invention for producing a continuous MS pattern laminated structure. 
       FIG. 9  is a detailed pictorial view showing top and bottom laminates of sheet material being secured to an MS patterned sheet of material. 
       FIG. 10  is a front pictorial view of an engraved set of final rollers for producing a folded core having a height of 0.25 inch in sheet material, for another embodiment of the invention. 
       FIGS. 11A and 11B  are respective pictorial views showing the geometry of the cleats of the set of rollers of  FIG. 10 . 
       FIG. 12  is a pictorial view of a portion of sheet material folded via use of the rollers of  FIG. 10 . 
       FIG. 13  is a front pictorial view of an engraved set of final rollers for producing a folded core having a height of 0.125 inch in sheet material, for another embodiment of the invention. 
       FIGS. 14A and 14B  are respective pictorial views showing the geometry of the cleats of the set of rollers of  FIG. 13   
       FIG. 15  is a pictorial view of a portion of sheet material folded via use of the rollers of  FIG. 13 . 
       FIG. 16  is a front pictorial view of a set of final folding rollers for producing a double-sided inclined folded core structure or pattern in a sheet of material, for another embodiment of the invention. 
       FIGS. 17A and 17B  are respective pictorial views showing the geometry of the cleats of the set of rollers of  FIG. 16 . 
       FIG. 18  is a pictorial view showing the process of splitting the double sided inclined folded core structure of the sheet material into two sheets or strips of singular inclined direction folded core structured material. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Generally speaking, the present invention is a machine for continuous folding of sheet materials. 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. 
   With reference to  FIG. 1 , the machine for continuous folding of this invention is generally referred to as number  10 . As 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  18  is a series of raised shapes that span the circumference of the roller. As described and shown below in certain embodiments of the invention, the tessellation(s)  18  are “V” shaped, whereas in other embodiments they appear as a series of successive cleat-like protrusions from each associated roller of a last set of rollers. 
   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 . 
   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 . 
   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  40 ,  42 , shown in this embodiment at numeral  30 . Each roller or die  36 ,  38  of the final set of rollers or dies  32  (also shown as a close up in  FIG. 4 ) has the same number of tessellations  18  as each roller or die  40 ,  42  of the penultimate set of rollers or dies  30 . 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 (when desired) to create sharp creases in the sheet material  15 . 
   Seven sets of rollers or dies 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 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. 
   Should the user decide to use the special rubber rollers or dies, however, each of either roller or die  36 ,  38  in the last set of rollers or dies  32  has the same amount of tessellations  18  as each roller or die  40 ,  42  in the penultimate set of rollers or dies  30 . 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. 
   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 . 
   The previously described embodiments of the invention produce through use of the final set of rollers of dies  32 , with each roller or die  36 ,  38  and tessellations  18  configured as shown in  FIG. 4 , a Chevron pattern in the final fold pattern  34  of the sheet material  15 . As previously indicated, the present machine can be modified in other embodiments of the invention for producing a plurality of other patterns in the sheet material  15 . For example, in another embodiment of the invention, the final or last set of rollers or dies  32  has tessellations  18  that are configured as shown in  FIGS. 5 ,  6 A, and  6 B, to provide a mating surfaces pattern as opposed to the previously described Chevron pattern, for ultimately folding the sheet material  15  to have a final fold pattern  34 , that is comparable to a honeycomb structure. For purposes of this description, this pattern is referred to as an MS pattern (Mating Surfaces Pattern) for a configuration of the tessellations  18 .  FIG. 5  shows the ultimate or left side of rollers or dies  32  of this MS pattern for the tessellations  18 .  FIG. 6A  is a detailed view of the configuration of the tessellations  18  and the MS pattern for each of the associated rollers  36  and  38 . The geometry of each of the cleat-like protrusions  50  of the MS pattern engraved on rollers  36 ,  38  is as shown in  FIG. 6B . The dimensions of “A” through “I” are shown in  FIG. 6B  in inches for producing an MS pattern with a final fold pattern  34  of the sheet material  15 , as shown in  FIG. 7 . Note that in  FIG. 6B  critical angles α and β are shown, which in the preferred embodiment, must be retained regardless of a change in the dimensions “A” through “I.” As indicated, the dimensions specifically shown in inches are in  FIG. 6B  are for producing 0.5 inch high MS pattern, which dimension can be smaller or larger by correspondingly changing the dimensions “A” through “I,” but in the preferred embodiment retaining the ratio therebetween as indicated for the 0.5 inch high MS pattern. Note that proportional dimensions are obtained for MS patterns with different heights. Note that adhesives (not shown) can be applied between the mating surfaces  52  to provide a structure that maintains its shape without having any laminated surfaces. 
   In another embodiment of the invention, in addition to directly gluing or applying adhesives between mating surfaces  52  of the MS patterned sheet material  15  as shown in  FIG. 7 , the material can be laminated. More specifically, in another embodiment of the invention, the machine  10  of  FIG. 2  is expanded as shown in  FIG. 8 , for automatically laminating the MS patterned sheet material  15 . With further reference to  FIG. 8 , the sheet material  15  is fed to the expanded machine  53  from a supply roller (not shown), and fed into a set of core punching rollers  54 , the purpose of which is to produce through holes similar to honeycomb (if this is desired). From the set of core punching rollers  54  the material  15  is fed into the plurality of sets of rollers or dies  12  previously described for the machine  10 , with the last set of rollers or dies  12  being rollers  36  and  38  each having tessellations  18  configured as shown in  FIG. 6A , as previously described. After the sheet material  15  exits from the MS configured rollers or dies  36 ,  38 , adhesive is applied to specific areas of the core via an adhesive applicator system  56 , with the material  15  proceeding to be compacted via a set of compacting rollers  58  surrounding the mated surfaces  52  of the MS folded pattern (see  FIG. 7 ), to adhere to each other. The material  15  is then fed into a traction unit  66  on which the top laminated material  61  is fed from a supply roll  62 , and bottom laminated material  63  is fed from a supply roll  64 , as shown. Laminated material  72  so produced is then fed through an adhesive curing system  60 , and pulled through the system by a pair of traction rollers  70 . The desired lengths of the laminated material  72  are cut by a flying cutter  69  located between the adhesive curing system  60  and the traction rollers  70 , in this example. Other traction rollers (not shown) move the finished and cut laminated product to a delivery area. The pictorial diagram of the MS patterned folded core material  34  as it is being laminated with a top laminate  61  and bottom laminate  63  is shown in  FIG. 7 . Note that the sheet material  15  can be a different material than the laminate material  61  and laminate material  63 , which themselves can be different materials. Also, as previously indicated, the folded core material  34  can be produced in different configurations for providing patterns of different heights and cell sizes, dependent upon the application, for changing the pattern on the final set of rollers  32 , as previously described. Also, the core punching rollers  54  can be disabled for turning off the punching system to provide for the core structures  34  without holes, if desired. The laminate material  61  and  63  can be paper, fiberboard, plastic material, and so forth. 
   As previously indicated, core structures having heights of less than 0.5 inch can be provided by a changing the configuration of the tessellations  18  of the last set of rollers  32 , as previously described. For example, the final roller set  32  shown in  FIG. 10  has a pattern engraved on the rollers  36  and  38  for producing a folded core in sheet material  15  having a height of 0.25 inch. The geometry for the pattern engraved on the rollers  36  and  38 , in this example is shown in  FIGS. 11A and 11B . To provide a vertical core pattern  34  of 0.25 inch high for the final set of rollers  32 , the individual rollers  36  and  38  thereof are engraved with the pattern shown in  FIG. 13 . The geometry for this latter pattern is shown in  FIGS. 14A , and  14 B. However, the geometries of the final set of rollers  32  for the engraved pattern for each of the associated rollers  36  and  38 , can be other than as provided in the previous examples for obtaining vertical core patterns  34  in the sheet material  15  having some other predetermined or desired height than illustrated above. 
     FIG. 12  shows the resultant folded core material having a height of 0.25 inch, for the example given above. A comparison thereto,  FIG. 15  shows the final fold pattern  34  having a folded core of 0.125 inch, produced as indicated above. The production of final fold pattern  34  of sheet material  15  provides a high stiffness-to-weight ratio of roller core tubes with a built-in partitioning surface. For example, the final fold patterns  34  of  FIGS. 12 and 15  are suitable for roll cores of metallic foils, and eliminate core detaching problems as found in the prior art. 
   In another embodiment of the invention an angular oriented folded core structure pattern is produced in a sheet material  15 , for providing a fold direction progressing at a predetermined angle to a longitudinal direction of rolling. To accomplish this, the present inventors had to overcome folding forces that generate a tangential component, which causes continuous shifting of the incoming sheet material  15  in the direction of inclination, that heretofore made it impossible to maintain the sheet material  15  within the rollers of machines of the prior art. The present inventors discovered that via the use of a double helix-like pattern in the rollers, the side force effect was eliminated. The final set of rollers  32  have tessellations  18  provided in the double helix pattern shown in  FIG. 16 . The final fold core structure  34  is a double-sided inclined structure, as shown. The geometry for the tessellations  18  for providing the doubled-sided inclined folded core structure  34  is shown in  FIGS. 17A and 17B . 
   The double-sided inclined folded core structure  34  can be split as shown in  FIG. 18 . The splitting process provides two singular inclined direction folded core structures  76 ,  78 , respectively, as shown in  FIG. 18 . 
   Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the examples chosen for purposes of disclosure and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention. Any such modifications and changes are meant to be covered by the spirit and scope of the appended claims.