JP2010540360A - Hinge-connected three-dimensional structure formed of two-dimensional sheet material - Google Patents

Abstract

The substantially two-dimensional sheet material is configured to bend along the bend line so as to form a three-dimensional structure having hinges along the bend line. The sheet material includes a sheet material that is substantially two-dimensional in the region where bending is performed, and a plurality of displacements in the thickness direction of the sheet material along opposite sides of the bending line, each displacement being , Having a shearing edge extending between its end portions and substantially parallel to the bend line. Adjacent shear edges overlap each other with respect to the bend line so as to form a hinge structure extending therebetween along the bend line, the hinge structure having hinge ends that conform in shape to the end portions. The hinge structure is dimensioned and configured for multiple bending and stretching cycles, thereby providing an integral hinge that connects opposing panels of sheet material on opposite sides of the bend line. A method of making and using a hinged three-dimensional structure is also disclosed.

Description

(Field of the Invention)
The present invention generally relates to a two-dimensional sheet material configured to form a three-dimensional structure having a hinge, and methods of using the same.

(Description of related technology)
Various methods have been developed to create sheet material for precise folding along the desired bend line. For example, Patent Literature 1, Patent Literature 2, Patent Literature 3, Patent Literature 4, and Patent Literature 5 are for forming a three-dimensional object having a relatively high dimensional tolerance from a substantially flat two-dimensional sheet. Various methods of creating and folding sheet material are described.

  The bending structure shown and described in the above patent promotes so-called edge-to-surface engagement and other phenomena to facilitate folding along the desired bend line. For example, a displacement can be formed to facilitate folding along a desired bend line, as described in the above invention.

  The three-dimensional object formed can be a housing and other structural items having the interior of the compartment and / or other forms. In many instances, periodic access to the interior may be required for assembly and construction, maintenance and service, and / or other purposes. In general, some disassembly is required to access the interior. Alternatively, a door or other member with a separate hinge may be provided for ease of access. On the downside, these components increase individual parts, individual hinges, and parts, complicate assembly, and generally require other parts and fasteners that require additional space and effort. To do.

US Pat. No. 6,877,349 US Pat. No. 6,877,349 US Pat. No. 7,032,426 US Pat. No. 7,152,449 US Pat. No. 7,152,450

  Thus, not only facilitates bending for assembly, but also provides an integral hinge structure to reduce the number of parts, simplify assembly, and / or facilitate access It would be beneficial to provide a sheet of material having a structure.

(Concise overview of the present invention)
One aspect of the invention relates to a method of creating a substantially two-dimensional sheet material for bending along a bend line to form a three-dimensional structure having hinges along the bend line. The method includes the following steps: obtaining a sheet material that is substantially two-dimensional in the region where bending occurs, and a plurality of displacements in the thickness direction of the sheet material along opposite sides of the bending line. Wherein each displacement has a shear edge extending between its end portions and substantially parallel to the bend line. Adjacent shear edges overlap each other with respect to the bend line so as to form a hinge structure extending therebetween along the bend line, the hinge structure having hinge ends that conform in shape to the end portions. The hinge structure is dimensioned and configured for multiple bending and stretching cycles, thereby providing an integral hinge that connects opposing panels of sheet material on opposite sides of the bend line.

  The obtaining step can be accomplished by obtaining a mild steel sheet material. The forming step can be accomplished by forming a displacement such that the shear edge can be at a distance from a bend line that can be at least 75% of the thickness (“T”) of the sheet material. The forming step may be by forming a displacement shear edge with a substantially linear portion extending between the curved portions, and the adjacent shear linear and curved portions may be at least about 6T. It can be achieved to overlap each other over distance. The step of forming may be accomplished by forming a displacement surface opposite the displacement shear edge, the method comprising engaging an edge-to-surface engagement between at least a portion of the shear edge and a portion of each displacement surface. The method may further include bending one of the opposing panels with respect to the other opposing panel about the bend line.

  The method may further include bending one of the opposing panels with respect to the other opposing panel about the bend line. The method may further include bending one of the opposing panels with respect to the other opposing panel around the bend line. The method further includes bending and extending one opposing panel relative to the other opposing panel at least 25 times, preferably at least 35 times, and most preferably at least 50 times about the bend line. obtain. The method may further include assembling the sheet material into a three-dimensional structure, one of the opposing panels providing a hinged panel for the three-dimensional structure that can be opened and closed.

  Another aspect of the invention relates to a substantially two-dimensional sheet material that is configured to bend along a bend line to form a three-dimensional structure having a hinge along the bend line. The sheet material includes a sheet material that is substantially two-dimensional in the region where bending is performed, and a plurality of displacements in the thickness direction of the sheet material along opposite sides of the bending line, each displacement being , Having a shearing edge extending between its end portions and substantially parallel to the bend line. Adjacent shear edges may overlap each other with respect to the bend line to form a hinge structure extending therebetween along the bend line, the hinge structure having a hinge end that conforms in shape to the end portion. Have. The hinge structure is dimensioned and configured for multiple bending and stretching cycles, thereby providing an integral hinge that connects opposing panels of sheet material on opposite sides of the bend line.

  The sheet material can be mild steel. The shear edge can be at a distance from the bend line, which can be at least 75% of the thickness of the sheet material (“T”). The substantially straight portion may extend between the curved portions, and adjacent shear straight and curved portions overlap each other over a distance that may be at least about 6T.

  The sheet material further comprises a displacement surface opposite the displacement shear edge, wherein the displacement causes at least a portion of the shear edge to bend around one of the opposing panels about the bend line with respect to the other opposing panel. An edge-to-surface engagement is configured between a portion of each displacement surface. The hinge structure may be configured to bend and extend at least 25 times. The hinge structure may be configured to bend and extend at least 50 times.

  In other embodiments, the three-dimensional structure may include the sheet material described above, and one of the opposing panels forms a hinged access cover for accessing a portion of the three-dimensional structure. The three-dimensional structure may be a box, and the hinged access cover may be a lid that provides access to the internal portion of the three-dimensional structure.

  A further aspect of the invention relates to a substantially two-dimensional sheet material that is configured to bend along a bend line to form a three-dimensional structure having a hinge along the bend line. The sheet material includes a sheet material that is substantially two-dimensional in the region where bending is performed and a plurality of tongues positioned along opposite sides of the bending line, each tongue having a bending line. , And has a surface extending substantially parallel to the bend line, the tongue extending between end portions that branch away from the bend line. Adjacent faces may overlap each other with respect to the bend line to form a hinge structure extending therebetween along the bend line, the hinge structure having hinge roots that are in shape with the end portions. . The hinge structure may be dimensioned and configured for multiple bending and stretching cycles, thereby providing an integral hinge that connects opposing panels of sheet material on opposite sides of the bending line.

  Both the methods and sheets of the present invention serve to illustrate certain principles of the present invention, and are apparent from or are further apparent from the accompanying drawings and the following detailed description of the invention, which are incorporated herein. Other features and advantages are described in detail.

FIG. 1A is a plan view of an exemplary two-dimensional sheet material positioned and configured to form a hinged three-dimensional structure in accordance with various aspects of the present invention, and FIG. It is an enlarged view. FIG. 1A is a plan view of an exemplary two-dimensional sheet material positioned and configured to form a hinged three-dimensional structure in accordance with various aspects of the present invention, and FIG. It is an enlarged view. FIG. 2 is an isometric view of a portion of the sheet material of FIG. 1 showing the displacement of the sheet material along a bend line that forms a hinge structure therebetween, according to various aspects of the present invention, and It is a detailed enlarged view. FIG. 3 is an isometric view of the sheet material of FIG. 1 showing its flange in a bent position. FIG. 4 is an isometric view of the sheet material of FIG. 1 showing its side in a bent position. FIG. 5 is an isometric view of the sheet material of FIG. 1 showing the top of itself in a bent position. FIG. 6 is an isometric view of the sheet material of FIG. 1 showing the top in the closed position, thereby forming a three-dimensional structure in the form of a housing. FIG. 7 is an isometric view of the sheet material of FIG. 1 showing the top in the open position, thereby providing access to the interior of the three-dimensional structure. 8 is an isometric view of a portion of the sheet material of FIG. 1, and a detailed enlarged view thereof, showing the hinge structure after the sheet material has been bent along a bend line.

(Detailed Description of the Invention)
Reference will now be made in detail to various embodiments of the invention, examples of which are illustrated in the accompanying drawings and described below. While the invention will be described in conjunction with the exemplary embodiments, it will be understood that the description is not intended to limit the invention to such exemplary embodiments. On the contrary, the present invention is not intended to cover only the exemplary embodiments, but is intended to include various improvements, modifications, equivalents, and other embodiments. This can be included within the spirit and scope of the invention as defined in the appended claims.

  In order to form a three-dimensional (3D) structure in the form of a housing 32 having a hinged access cover 33, with reference now to the drawings wherein like components are designated by like reference numerals throughout the various views. Attention is directed to FIGS. 1A and 1B and FIG. 2, which discloses an exemplary two-dimensional (2D) sheet material 30 that has been positioned and configured. There are numerous applications where 2D sheet material can be formed into a 3D structure, as described in the following invention and invention applications.

  The depiction of the enclosure is exemplary only and the teachings of the present invention for precise bending are electrical parts, automotive parts, transportation parts, building parts, instrument parts, truck parts, RF shields, HVAC parts, aviation parts. It is also applicable to the manufacture of many other 3D structures having hinged connection panels including but not limited to. That is, the teachings of the present invention are applicable to a wide range of 3D products and structures that are formed by folding 2D sheet material and that can benefit from having a hinged access cover. Such a 3D structure may be further advantageous in that the present invention allows the 3D structure to be reduced to its flat form to facilitate repackaging and reshipment. These features are particularly suitable for producing reusable shipping containers and the like.

  In many aspects, the sheet material of the present invention comprises US Pat. No. 6,481,259, US Pat. No. 6,877,349, US Pat. No. 7,152,449, US Pat. No. 7,152,450. US Patent Application No. 10 / 821,818 (Publication No. 2005/0005670), US Patent No. 7,032,426, US Patent No. 7,263,869, US Patent No. 7,222,511 US Patent Application No. 11 / 357,934 (Publication No. 2006/0261139), US Patent Application No. 10 / 952,357 (Publication No. 2005/0064138), US Patent Application No. 11 / 384,216 ( (Publication No. 2006/0207212), US Patent Application No. 11 / 080,288 (Publication No. 2005/0257589), US Patent Application No. 11 / 374,8 8 (Publication No. 2006/0213245), US Patent Application No. 11 / 180,398 (Publication No. 2006/0021413), US Patent Application No. 11 / 290,968 (Publication No. 2006/0075798), US Patent Application No. 11 / 411,440 (Publication No. 2007/0113614), US Provisional Patent Application No. 60 / 665,577, US Patent Application No. 11 / 386,463 (Publication No. 2006/0277965), and Similar to those disclosed by US Provisional Patent Application No. 60 / 854,846, the entire contents of these patents and patent applications are incorporated herein by reference.

  The sheet material is formed of an incompressible material. Suitable materials include relatively ductile materials such as metals, including but not limited to mild steel, crude steel, and processed steel, such as galvanized steel, stainless steel, aluminum, and alloys thereof.

  The sheet material 30 includes a plurality of bent structures 35 formed in the sheet material positioned along the bend lines 37, similar to those described in the above patents and patent applications. In the illustrated embodiment, the bend line is configured to define a housing side 39 and a housing end 40 extending from the housing base 42, as well as a housing side 39 ′ extending from the access cover 33. The flexure structure allows for precise folding of the sheet material along the flex line to ultimately position the base, side edges and access cover in the desired relationship to form a 3D housing. Formed and oriented. It will also be appreciated that the number, position, and relative orientation of the bent structures and bend lines will vary depending on the desired shape of the desired 3D structure.

  In the illustrated embodiment, as shown in FIG. 1A, the bend structure 35 is one of the bend lines 37 to facilitate bending along the 2D sheet material to bend into a 3D structure. Extending along the side. It will be appreciated that a bent structure may be formed along opposite sides of the bend line to facilitate bending, as described in the above patents and patent applications. In exemplary embodiments, the flexure structure is displacement, but other flexure structures may be used, such as slits, displacements, grooves, and / or other flexure-promoting structures described in the above patents and patent applications. It is understood.

  In accordance with the present invention, certain bend lines may be configured to serve as hinges that are integrally formed with other portions of the sheet material. For example, the exemplary embodiment allows the access cover 33 to bend staggered multiple times, thereby providing the housing 32 with a hinged access cover that allows access to the interior of the housing. It includes a bend line 44 having a single hinge configured to serve as 46 (see, eg, FIGS. 5, 6, and 7). It will be appreciated that if a panel with multiple hinges is desired, the sheet of material may comprise a bend line having one, two, three or more hinges. Further, the 2D sheet material may comprise a die cut portion having one or more hinges that allow partial access. For example, a bend line 44 'having a hinge is configured to act as a hinge 46', allowing the knockout panels to bend in a staggered manner as well.

  The bend line 44 having a hinge includes a displacement 47 disposed on both sides of the bend line 44 having a hinge. In many respects, the displacement is similar to that described in the above patents and patent applications. For example, each displacement 47 includes a tongue 49 that is displaced from the overall flat surface of the sheet material 30. An exemplary embodiment of a tongue is shown in FIGS. 2 and 1B, which shows how the tongue 49 is displaced on the above-described overall flat surface of the sheet material. FIG. 1B is a bottom view showing a recess in the sheet material formed by the displacement of the tongue-like portion.

  The exemplary tongue extends substantially parallel to the flat portion of the sheet material and maintains a connection to the rest of the sheet material by an inclined transition zone 51. Exemplary flat and parallel configurations of the tongue can promote tool life and other advantages, but the tongue need not be flat and / or exactly parallel to the rest of the sheet material It is understood. Opposing transition zone 51 is a sheared surface 53 that extends along the length of displacement 47. In the exemplary embodiment, the sheared surface has a relatively straight central portion 53 'and a curved end portion 53 "that diverge away from the bend line. The displacement may be formed by stamping, die cutting, roll forming and / or other suitable means similar to those described in the above patents and patent applications.

  The displacement 47 along the bend line 44 with the hinge may have a similar general configuration as the displacement utilized elsewhere in the sheet material, but with respect to the bend line with the hinge and relative to each other. The position and arrangement of the displacement 47 is particularly suitable for functioning as a hinge 46. In particular, the displacements 47 are staggered in a bend line 44 having a hinge, as shown in FIGS. 1A and 1B. More specifically, the displacement 47 is spaced from a bend line having a hinge so as to overlap with an adjacent displacement. Preferably, the overlap length is greater than about 6-7 times the thickness of the sheet material (“T”). Increasing the length of the overlap distributes the axial twist at larger lengths, thus providing a good hinge shape for various applications.

  Further, the displacement is preferably located at a distance of at least about 75% to 100% -125% of the thickness of the sheet material from the bend line of the hinge structure, which has an overlap of about 1.5T to 2T. This corresponds to the bend ("J") distance between. In some embodiments, the curvature may be as wide as 3T or 4T. Such an arrangement allows manufacturing using conventional stamping, die cutting and roll forming techniques.

  Such a configuration of displacements generally defines a hinge structure 54 that extends between overlapping portions of adjacent displacements 47. A portion of the hinge structure extends along a bend line 44 having a hinge that interconnects the housing end 40 ′ to the access cover 33 in the exemplary embodiment that interconnects opposing panel portions. In addition, the hinge structure includes a bifurcated portion or root 56 that is formed by a curved end portion 53 ″ of a sheared surface and branches away from a bend line that conforms to this shape. Furthermore, the posture of the route after folding is largely formed by contact with the adjacent displacement 47. Preferably, the curved end portion has a relatively large radius of curvature that acts as a stress distribution device to distribute the stress at the end of the hinge structure 54. The radius of curvature of the curved end portion 53 ″ is preferably greater than the thickness of the sheet material, preferably a few times greater than the thickness of the sheet material, and more preferably about 3 times the thickness. That's it.

  The curved end portion serves to increase the cross-sectional area of the hinge structure in order to connect to the remaining portion of the sheet material. Such a configuration is believed to distribute the torsional stress in the hinge structure during flexion (and extension), where the torsional stress is schematically illustrated as arrow “T” in FIG. 1B. Further, such a configuration is believed to readjust the material stress at the end of the hinge structure by the adjacent material in the rest of the sheet, which is schematically illustrated by arrow “B” in FIG. 1B. .

  Such a configuration has been shown to greatly improve the number of flex / extension cycles and that the hinge structure can withstand failure. For example, an exemplary configuration of mild steel sheet metal incorporating a hinge structure can withstand 25 or more flex / extension cycles without failure, and in some examples, without axial shearing at the flex line with the hinge, It can withstand more than 50 cycles without and / or other propagation of shear adjacent to this bend line. Preferably, the hinge is configured to withstand at least 35 cycles, more preferably at least 45 cycles.

  Such a configuration may further facilitate a “wrapping” operation that imparts tension and twist (eg, see arrow “B” in FIG. 1B) to the root 56 of the sheet material immediately adjacent to the large radius edge. The route can also help to facilitate precise bending along the bend line since it appears to promote bend-assisted tension and twist in the direction that the bend lines intersect.

  That is, the folding of the sheet material is almost similar to the methods described extensively in the above patent applications and patents. The main difference is that at the completion of the folding, the hinge structure 54 is “designed” in the structure by varying certain parameters including curvature (eg, hinge width) and overlap size (eg, hinge length). It allows repeated bending and stretching along the hinged bend line 44 without the material failure of the specific number of cycles possible.

  Next, a method of folding a 2D sheet material into a 3D structure will be described with reference to FIGS. The exemplary sheet material 30 is provided with a number of assembled side flanges 58 and access cover flanges 60. As the sheet material is bent along its respective bend lines, the side flanges are positioned and configured to secure the sides and ends together. In an exemplary embodiment, side flanges and assembled side flanges are described in US patent application Ser. No. 11 / 386,463 (currently published 2006/0277965), the entire contents of which are hereby incorporated by reference. Similar to what is described, it comprises cooperating latch means that are integrally formed. Access cover flange 60 is positioned and configured by similar latching means located on opposing housing ends 40. It will be appreciated that other suitable latching means may be utilized and that it is not necessary to provide latching means if so desired.

  Preferably, the side and panel flanges are bent by stamping, die cutting, squeeze rolls or other suitable means, resulting in the orientation shown in FIG. However, it is understood that a bent structure may be provided to facilitate position determination by bending of such a flange.

  As shown in FIGS. 4 and 5, the housing side 39 and the housing end 40 can then be bent relative to the housing base 42. When the sides and ends are folded and positioned, the cooperating latch means engage, thereby securing the side flange 58 to the housing side 39. Alternatively, the side flange can be fixed to the housing side by known fastening means.

  Finally, as shown in FIG. 6, the access cover 33 can be folded about the hinge bend line 44 so that the access cover pivots to its closed position. Preferably, the access cover flange is positioned and configured to cooperate with latch means provided on the opposite housing end 40 to securely hold the access cover in its closed position. Such a latching means may be self-locking, but it may be preferred not to use such a self-locking configuration to facilitate reopening of the access cover. Alternatively, the access cover flange can be secured to the opposite housing end by known fastening means.

  As desired, the access cover 33 may be reopened as shown in FIG. 7 to allow access within the enclosure. For example, if the housing 32 is a housing for electrical components, it may be desirable to be able to access the interior of the housing periodically. The hinge 46 eliminates the need for a separate hinge that connects the access cover to the rest of the housing, thereby allowing such access while reducing component count, assembly cost, and complexity.

  Referring again to FIG. 1A, a knockout panel 33 'can be utilized, similar to an access cover. In addition, the 2D sheet material may be provided with one or more knockouts 61, integrally formed tabs that interconnect the remote end of the panel 33 'along with the rest of the sheet. Unlike a conventional die-cut panel that becomes a separate member when the tab breaks, the panel 33 'maintains a connection to other parts of the sheet material by an integrally formed hinge 46'.

  For convenience of explanation and precise provisions in the appended claims, the terms “above” or “above”, “below” or “below”, “inner” and “outer” With reference to the location of the feature, it will be used to describe the feature of the exemplary embodiment.

  The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise form disclosed, and many modifications and variations are possible in light of the above teaching. it is obvious. Describe the specific principles of the invention and its practical applications, so that those skilled in the art can make and use various exemplary embodiments of the invention, as well as various alternatives and modifications thereof. To do so, exemplary embodiments have been selected and described. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (20)

A method of making a substantially two-dimensional sheet material that bends along a bend line so as to form a three-dimensional structure having a hinge along the bend line, the method comprising:
Obtaining a sheet material that is substantially two-dimensional in the region in which bending occurs;
Forming a plurality of displacements in the thickness direction of the sheet material along opposite sides of the bend line, each displacement extending between its end portions and substantially in the bend line; Adjacent shear edges overlap each other with respect to the bend line so as to form a hinge structure extending therebetween along the bend line, the hinge structures being The hinge structure is dimensioned and configured for multiple bending and stretching cycles, thereby opposing the bend line to the opposite end of the bend line. A method for providing an integral hinge connecting opposing panels of sheet material.   The method of claim 1, wherein the obtaining step is accomplished by obtaining a mild steel sheet material.   The forming step is accomplished by forming the displacement such that the shear edge is at a distance of at least 75% of the thickness ("T") of the sheet material from the bend line. The method according to 1.   The forming step is accomplished by forming the displaced shear edge with a substantially linear portion extending between the curved portions, whereby adjacent shear linear and curved portions are at least 4. The method of claim 3, wherein the methods overlap each other over a distance that is approximately 6T.   The forming step is accomplished by forming a displacement surface opposite the displacement shear edge, the method comprising engaging an edge to a surface between at least a portion of the shear edge and a portion of the respective displacement surface. The method of claim 1, further comprising bending one of the opposing panels with respect to the other opposing panel about the bend line to produce a match.   The method according to claim 1, further comprising bending one of the opposing panels with respect to the other opposing panel around the bend line.   The method according to claim 1, further comprising bending one of the opposing panels with respect to the other opposing panel around the bend line.   The method according to claim 7, further comprising bending and extending the one opposing panel with respect to the other opposing panel at least 10 times around the bending line.   The method of claim 1, further comprising assembling the sheet material into a three-dimensional structure, wherein one of the opposing panels provides a hinged panel for the three-dimensional structure that can be opened and closed. A substantially two-dimensional sheet material configured to bend along the bend line to form a three-dimensional structure having hinges along the bend line, the sheet material comprising:
A sheet material that is substantially two-dimensional in the region in which bending occurs;
A plurality of displacements in the thickness direction of the sheet material along opposite sides of the bend line, each displacement extending between its end portions and substantially parallel to the bend line; A displacement having a shearing edge, and
Adjacent shear edges overlap each other with respect to the bend line so as to form a hinge structure extending therebetween along the bend line, the hinge structure having a hinge end that conforms to the end portion. Have
The sheet material is dimensioned and configured for multiple flexing and stretching cycles, thereby providing an integral hinge that connects opposing panels of the sheet material on opposite sides of the bending line.   The sheet material according to claim 10, wherein the sheet material is mild steel.   The sheet material of claim 10, wherein the shear edge is at a distance of at least 75% of the thickness (“T”) of the sheet material from the bend line.   11. The sheet material of claim 10, wherein the displaced shear edges comprise substantially straight portions and adjacent shear straight portions overlap each other over a distance that is at least about 3T.   14. The sheet material of claim 13, wherein the substantially straight portion extends between curved portions and adjacent shear straight and curved portions overlap each other over a distance that is at least about 5T.   A displacement surface facing the displacement shear edge, wherein the displacement is caused by bending one of the opposed panels with respect to the other opposed panel around the bending line, and at least a part of the shear edge. 11. A sheet material according to claim 10, configured to cause edge-to-surface engagement between a portion of each displacement surface.   The sheet material of claim 10, wherein the hinge structure is configured to bend and extend at least 10 times.   The sheet material of claim 10, wherein the hinge structure is configured to bend and extend at least 50 times.   11. A three-dimensional structure comprising the sheet material of claim 10, wherein one of the opposing panels forms a hinged access cover for accessing a portion of the three-dimensional structure.   The three-dimensional structure according to claim 18, wherein the structure is a box and the hinged access cover is a lid that provides access to the interior of the three-dimensional structure. A substantially two-dimensional sheet material configured to bend along the bend line to form a three-dimensional structure having hinges along the bend line, the sheet material comprising:
A sheet material that is substantially two-dimensional in the region in which bending occurs;
A plurality of tongues positioned along opposite sides of the bend line, each tongue being directed toward the bend line and extending substantially parallel to the bend line; And the tongue includes a tongue extending between end portions branching away from the bend line, and
Adjacent surfaces overlap each other with respect to the bend line so as to form a hinge structure extending therebetween along the bend line, the hinge structure having a hinge root whose shape coincides with the end portion. Have
The sheet material is dimensioned and configured for multiple flexing and stretching cycles, thereby providing an integral hinge that connects opposing panels of the sheet material on opposite sides of the bending line.

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