Abstract:
A folded sheet assembly and method of manufacture includes a sheet having an un-folded state with a pre-determined bend-line. The sheet may be weakened along the bend-line to facilitate precise bending of the sheet and into a folded state. A segment of the assembly is additively manufactured to the bend for reinforcement. Weakening of the sheet along the bend-line may be achieved by placement of perforations through the sheet when in the unfolded state. The perforations may be filled by the segment when the sheet is in the folded state.

Description:
[0001]    This application claims priority to U.S. Patent Appln. No. 62/008,926 filed Jun. 6, 2014. 
     
    
     BACKGROUND 
       [0002]    The present disclosure relates to sheet bends, and more particularly, to sheet bends enhanced through additive manufacturing. 
         [0003]    There is an ongoing demand for low cost manufacturing technology, storage and packaging methodology, installation approaches, and low cost construction assembly methods suitable for industrial businesses. For instance, structures may be designed and shipped to installation or final manufacturing sites as a metal flat sheet. Once on-site, the sheet may be selectively folded to create a desired final structure or component. 
         [0004]    Bending of sheet material at pre-specified bend locations is difficult to control because of bending tolerance variation and the accumulation of such defects over multiple bend applications. To assist in reducing such bend variation, it is known to form intermittent slits, perforations and/or grooves along, or close to, a pre-specified bend location, or bend-line. Non-limiting examples of such sheet bending is further taught in U.S. Patent Publication Number 2011/0059330, published on Mar. 10, 2011, and assigned to Industrial Origami, Inc. of Middleburg Heights, Ohio, and incorporated herein by reference in its entirety. Unfortunately, the slitting-based and grooving-based bending of sheet material may structurally weaken the bend and produce residual stresses due to plastic deformation. Yet further, slitting-based bending and other similar methods may further produce undesirable apertures, voids or cracks that communicate through the folded sheet assembly at the bend location, may be susceptible to corrosion and environmental exposure, and may retain sharp and aesthetically unpleasing edges. 
       SUMMARY 
       [0005]    A folded sheet assembly according to one, non-limiting, embodiment of the present disclosure includes a bend; and an additive manufactured segment located at the bend. 
         [0006]    Additionally to the foregoing assembly a perforation is located along the bend and the segment fills at least a portion of the perforation. 
         [0007]    In the alternative or additionally thereto, in the foregoing embodiment, the assembly includes a first sheet portion having a first edge face proximate to the bend; a second sheet portion engaged to the first sheet portion at the bend, and having a second edge face proximate to the bend; and wherein the segment is additively manufactured to at least the first and second edge faces. 
         [0008]    In the alternative or additionally thereto, in the foregoing embodiment, the assembly includes an inner side defining a groove extending along the bend; an outer side generally in plastic deformation along the bend; and wherein the segment is additively manufactured to the second side at the bend. 
         [0009]    In the alternative or additionally thereto, in the foregoing embodiment, the segment is cold sprayed. 
         [0010]    In the alternative or additionally thereto, in the foregoing embodiment, the segment is produced through Kinetic Metallization. 
         [0011]    In the alternative or additionally thereto, in the foregoing embodiment, the segment is cold sprayed. 
         [0012]    In the alternative or additionally thereto, in the foregoing embodiment, the segment is produced through cold metal transfer. 
         [0013]    In the alternative or additionally thereto, in the foregoing embodiment, the segment is additively manufactured through laser beam melting that relieves plastic deformation stress. 
         [0014]    In the alternative or additionally thereto, in the foregoing embodiment, the segment is additively manufactured through laser beam melting that relieves plastic deformation stress. 
         [0015]    In the alternative or additionally thereto, in the foregoing embodiment, the segment is additively manufactured through electron beam melting that relieves plastic deformation stress. 
         [0016]    In the alternative or additionally thereto, in the foregoing embodiment, the segment is additively manufactured through electron beam melting that relieves plastic deformation stress. 
         [0017]    In the alternative or additionally thereto, in the foregoing embodiment, the segment is additively manufactured through electron beam melting that relieves plastic deformation stress. 
         [0018]    A method of manufacturing a folded sheet assembly according to another, non-limiting, embodiment includes the steps of pre-determining a bend-line along a sheet of material; bending the sheet along the bend-line; and additively manufacturing a segment upon a bend at the bend-line. 
         [0019]    Additionally to the foregoing embodiment, the bending creates residual stress at the bend and the additively manufactured segment is produced through a heat gun that relieves the residual stress. 
         [0020]    In the alternative or additionally thereto, in the foregoing embodiment, the method includes the step of forming a perforation in the sheet along the bend-line prior to bending. 
         [0021]    In the alternative or additionally thereto, in the foregoing embodiment, the segment fills an aperture proximate to the bend-line. 
         [0022]    In the alternative or additionally thereto, in the foregoing embodiment, the perforation is defined between two opposing edge faces and the segment is additively manufactured to the edge faces. 
         [0023]    In the alternative or additionally thereto, in the foregoing embodiment, the additively manufactured segment is cold sprayed. 
         [0024]    In the alternative or additionally thereto, in the foregoing embodiment, the assembly is a fluid tight enclosure. 
         [0025]    The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in-light of the following description and the accompanying drawings. It should be understood, however, the following description and figures are intended to be exemplary in nature and non-limiting. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiments. The drawings that accompany the detailed description can be briefly described as follows: 
           [0027]      FIG. 1  is a plan view of a sheet in an un-folded state of a folded sheet assembly; 
           [0028]      FIG. 2  is a cross section of the folded sheet assembly taken along line  2 - 2  of  FIG. 1 ; 
           [0029]      FIG. 3  is a cross section of the folded sheet assembly taken along line  3 - 3  of  FIG. 1 ; 
           [0030]      FIG. 4  is a plan view of a second embodiment of a sheet in an un-folded state of a folded sheet assembly; 
           [0031]      FIG. 5  is a side view of the folded sheet assembly; 
           [0032]      FIG. 6  is a cross section of the folded sheet assembly taken along line  6 - 6  of  FIG. 5 ; and 
           [0033]      FIG. 7  is a flow chart of a method of manufacturing a folded sheet assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    Referring to  FIG. 1 , an example of a substantially planar sheet  20  is illustrated in a un-folded state  22  and having a pre-determined bend-line  24 . The sheet  20  may be a metal, alloy, polymer or composite sheet, and may have a plurality of slits or perforations  26  and/or at least one groove  28  positioned along the bend-line  24  to assist in the bending or folding of the sheet  20  along the bend-line  24  and into a folded state  30  (see  FIGS. 2 and 3 ). The sheet  20  has an outer side  32  and an opposite inner side  34  with the groove  28  generally defined by the inner side  34 . When in the folded state  30 , a resultant bend  36  along the bend-line  24  generally connects a first portion  38  to a second portion  40  of the sheet  20  that are in angular relationship to one-another. 
         [0035]    When in the un-folded state  22 , the slits  26  are each defined by opposing edge faces  42 ,  44  carried by the respective first and second portions  38 ,  40  of the sheet  20 . When in the folded state  30 , the edge faces  42 ,  44 , or any portion thereof, may or may not oppose one-another and are proximate to, or generally in, the bend  36 . Furthermore, the slits  26  may communicate through the sheet  20  even when in the folded state  30  or may otherwise reposition and open up further apertures  41  that communicate through the sheet. The folding process plastically deforms a base material segment  46  of the sheet  20  that is in or crosses through the bend  36  and generally maintains engagement of the first and second portions  38 ,  40 . When deformed, the base material segment  46  may have residual stress that is particularly prominent at and near the outer side  32  (i.e. tension). This stress, along with the slits and grooves  26 ,  28 , structurally weakens the bend  36  and may further promote corrosion at the bend location. Furthermore, undesirable sharp edges  48  may be formed where the edge faces  34 ,  36  meet the outer side  32 . 
         [0036]    Referring to  FIG. 2 , a folded sheet assembly  50  is illustrated having the sheet  20  when in the folded state  30  and an additive manufactured filler material or segment  52 . Segment  52  is additive manufactured directly to the bend  36 . The segment  52  may further be formed directly to the edge faces  42 ,  44  and/or base material segment(s)  46  (see  FIG. 1 ) thereby filling the slits  26  and or apertures  41  creating a more structurally sound bend  36 . As best shown in  FIG. 3  and alternatively or in addition thereto, the segment  52  may be formed directly to the outer side  32  of the sheet  20 . Segment  52  may also be located on the inside of the bend  36 . After the additive manufacturing process is complete, the segment  52  and/or bend  36  may be machined, or otherwise modified, to form the desired or aesthetically pleasing shape. The folded sheet assembly  50  may be any type of final product including bended electrical terminals, electrical boxes, fluid tight enclosures, transportation type enclosures, storage enclosures, structural elements and/or any type of product where precision bending and a structurally rigid assembly is desired. 
         [0037]    An additive manufacturing system  54  used to apply the segment  52  to the sheet  20  when in the folded state  30  may be any number of systems generally known in the art, including Cold Spray or Kinetic Metallization, Cold Metal Transfer (CMT), Additive Layer Manufacturing (ALM) devices, such as Direct Metal Laser Sintering (DMLS), Selective Laser Melting (SLM), Laser Beam Melting (LBM), Electron Beam Melting (EBM), or other suitable solid freeform fabrication method, and which may provide for the fabrication of metal, alloy, polymer, ceramic and composite structures by the freeform construction of the segment  52 . Each system  54  may have a controller  56  that generally operates an energy gun  58  and a powder, wire or strip delivery system  60  through electrical signals  62 . 
         [0038]    If the additive manufacturing system  54  utilizes the Cold Spray or Kinetic Metallization technology, a raw material or powder  66  is typically applied to the sheet  20  at supersonic speeds thus the energy gun  58  and the powder delivery system  60  are generally integrated. Such systems do not require a vacuum to operate, and do not intentionally create or require melting, thus are less prone to solidification defects. Moreover, the raw material may be of a different composition than the base material, and a durable bond can still be formed through particle-to-particle impact. Although not shown, the controller  56  may be part of, or control a robotic arm that senses and moves the energy gun  58  and delivery system  60  along the bend  36 . The system  54  is relatively simple and may be generally portable making Cold Spray or Kinetic Metallization an ideal choice for larger and bulkier assemblies  50 . It is further contemplated and understood that similar example descriptions may apply to wire feed and cold metal transfer technologies. 
         [0039]    Alternatively, the energy gun  56  may be an electron beam or laser energy gun. The principle behind such additive manufacturing systems involves the selective melting of atomized precursors, powder beds, powder spray, or wire feed  66  (as examples) by the energy gun  58 , producing a build-up of the segment  52 . For instance, and when applying a laser or electron energy beam, melting of the powder or wire occurs in a small localized region of an energy beam  64 , producing small volumes of melting, called melt pools, followed by rapid solidification, allowing for very precise control of the solidification process in a layer-by-layer fabrication of the segment  52 . The controller  56  may be directed by three-dimensional geometry solid models developed in Computer Aided Design (CAD) software systems. The heating and melting aspect of the electron beam and laser energy guns will heat and melt a small portion of the base material, thereby relieving residual stresses created during plastic deformation of the base material segments  46  of the sheet  20 . 
         [0040]    Non-limiting examples of the feed wire, strip or powder may include ceramics, metals, polymers, carbon-based materials or a mixture of ceramic, polymer, carbon and/or metal. Non-limiting examples of ceramics may include oxide ceramics such as Al 2 O 3  or ZrO 2 , carbide materials such as silicon carbide and boron carbide, and nitride ceramics such as aluminum nitride, silicon nitride. Non-limiting examples of metals may include nickel or nickel alloys, titanium or titanium alloys, cobalt and cobalt alloys, copper and copper alloys, ferrous metals such as steel alloys, stainless steel, and non-ferrous metals such as aluminum, aluminum alloys, and bronze. Non-limiting examples of mixtures may include aluminum-silicon metal matrix composites, carbon nanotube-filled copper, WC—Co cermets, polymer encapsulated SiC powders, and polymer-precursor blends containing aluminum powders. 
         [0041]    Referring to  FIGS. 4 through 6 , a second embodiment of a folded sheet assembly is illustrated wherein like elements have like identifying numerals except with the addition of a prime symbol. A sheet  20 ′ in the un-folded state  22 ′ has a plurality of slits  26 ′ that co-extend longitudinally along a bend-line  24 ′. Each slit  26 ′ is laterally offset, but proximate to, the bend-line  24 ′ and such that one slit is located on one side of the bend-line and the next adjacent slit is located on the other side of the bend-line. Moreover, each slit  26 ′ longitudinally overlaps the next adjacent slit and thereby defines a base material segment  46 ′ there-between. 
         [0042]    When in a folded state  30 ′, a resultant bend  36 ′ along the bend-line  24 ′ generally connects a first portion  38 ′ to a second portion  40 ′ of the sheet  20 ′ that are in angular relationship to one-another. An additive manufactured segment  52 ′ is formed directly to the portions  38 ′,  40 ′ at the bend  36 ′ and fills at least a portion of the slits  26 ′ and any resulting apertures  41 ′ formed as a result of the bending process. The sheet  20 ′ in the folded state  30 ′ and the segment  52 ′ together form a folded sheet assembly  50 ′. 
         [0043]    Referring to  FIG. 7 , a method of manufacturing a folded sheet assembly  50 ,  50 ′ may include an initial step  100  of cutting a substantially planar sheet  20 ,  20 ′ to a pre-determined size and shape using a non-limiting exemplary process such as embossing, cutting, slitting, grooving or stamping. Step  102  includes pre-defining at least one bend-line  24 ,  24 ′, then at step  104 , weakening an area of the sheet  20 ,  20 ′ along the bend-line  24 ,  24 ′ through the formation of perforations, slits, stamped regions, and/or grooves  26 ,  26 ′,  28 ,  28 ′. The next step  106  is bending the sheet  20 ,  20 ′ along the bend line  24 ,  24 ′ thereby causing plastic deformation of a base material segment  46 ,  46 ′ located proximate to the bend  36 ,  36 ′. Once the sheet is bended, step  108  includes reinforcing the bend  36 ,  36 ′ by additively manufacturing a segment  52 ,  52 ′ directly to the sheet  20 ,  20 ′ and in any perforations  26 ,  26 ′ and/or apertures  41 ,  41 ′ in the sheet  20 ,  20 ′. As a final step  110 , the bend  36 ,  36 ′ and/or the segment  52 ,  52 ′ may be machined, or otherwise post processed, to contour the reinforced bend into a desirable shape and surface texture, or to impart other desirable properties to the sheet or additive manufactured segment or bend. 
         [0044]    It is understood that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like are with reference to the normal operational attitude and should not be considered otherwise limiting. It is also understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will also benefit. Although particular step sequences may be shown, described, and claimed, it is understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure. 
         [0045]    The foregoing description is exemplary rather than defined by the limitations described. Various non-limiting embodiments are disclosed; however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For this reason, the appended claims should be studied to determine true scope and content.