Patent Publication Number: US-2021178457-A1

Title: Metallic sheet securement

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional application Ser. No. 62/948,519 filed Dec. 16, 2019, the disclosure of which is hereby incorporated in its entirety by reference herein. 
    
    
     TECHNICAL FIELD 
     Various embodiments relate to heating and securing of metallic sheets with fasteners. 
     BACKGROUND 
     Pfeiffer et al., U.S. Pat. No. 9,901,974 B2 discloses an example for flow hole screw fastening of structural components. 
     SUMMARY 
     According to at least one embodiment, a method for metallic sheet securement contacts a first metallic sheet and a second metallic sheet with each other with one of the metallic sheets being advanced high strength steel and having a joining location. A light-safe laser beam is projected upon, to thereby heat the joining location of the one metallic sheet. A flow fastener that is either a flow form screw or a flow push screw is inserted through the one metallic sheet at its heated joining location and also through the other metallic sheet to secure the metallic sheets to each other. 
     According to a further embodiment, both the first and second metallic sheets are advanced high strength steel. The light-safe laser beam impinges with the first metallic sheet and the flow fastener is initially inserted through the first metallic sheet and subsequently through the second metallic sheet to secure the metallic sheets to each other. 
     According to another further embodiment, the first metallic sheet is mild steel or aluminum and has a hole through which the light-safe laser beam is projected and through which the flow fastener is inserted. The second metallic sheet is advanced high strength steel and is heated by the light-safe laser beam and into which the flow fastener is inserted to secure the metallic sheets to each other. 
     According to another further embodiment, the first metallic sheet is advanced high strength steel and the second metallic sheet is mild steel or aluminum and is imperforate. The light-safe laser beam impinges with the first metallic sheet and the flow fastener is initially inserted through the first metallic sheet and subsequently through the second metallic sheet to secure the metallic sheets to each other. 
     According to another further embodiment, both the first and second metallic sheets are advanced high strength steel. The light-safe laser beam impinges with the second metallic sheet and the flow fastener is initially inserted through the first metallic sheet and subsequently through the second metallic sheet to secure the metallic sheets to each other. 
     According to another further embodiment, the first metallic sheet is mild steel or aluminum and is imperforate. The second metallic sheet is advanced high strength steel. The light-safe laser beam impinges with the second metallic sheet and the flow fastener is initially inserted through the first metallic sheet and subsequently through the second metallic sheet to secure the metallic sheets to each other. 
     According to another further embodiment, there are at least three metallic sheets in contact with each other and with the first metallic sheet and another one of the metallic sheets being advanced high strength steel and having outer surfaces facing outwardly in opposite directions to each other with aligned joining locations where light-safe laser beams projected in opposite directions respectively impinge to provide heating and through which the flow fastener is inserted to secure all of the metallic sheets to each other. 
     According to another embodiment, a heating and joining apparatus for metallic sheet securement is provided with tooling with a first end. A laser system is provided to selectively project a first light-safe laser beam from the first end of the tooling toward a workspace. A flow fastener driver is provided to supply flow fasteners of either a flow form screw type or a flow push screw type from the first end of the tooling to the workspace to secure metallic sheets to each within the workspace after heating of at least one of the metallic sheets, which is advanced high strength steel, within the workspace by the laser system. A controller is provided to operate the laser system and the flow fastener driver in coordination with each other to provide the securement of the metallic sheets to each other. 
     According to a further embodiment, the controller selectively operates the laser system to supply the first light-safe laser beam to provide the heating. 
     According to another further embodiment, a robot is provided to move the tooling to selected locations to perform the metallic sheet heating and joining. 
     According to another embodiment, an assembly is provided with at least one sheet of advanced high strength steel (AHSS) and a second metallic sheet. A flow fastener is fastened to the at least one sheet of AHSS and the second metallic sheet. 
     According to a further embodiment, the AHSS has a tensile strength of at least 980 megapascals. 
     According to another further embodiment, the flow fastener is provided as a flow form screw or a flow push screw. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevation view of an apparatus to provide metallic sheet securement according to an embodiment; 
         FIG. 2 a    is a side section view of metallic sheet securement with a laser according to an embodiment; 
         FIG. 2 b    is a side section view of the metallic sheet securement of  FIG. 2 a    with a flow fastener according to an embodiment; 
         FIG. 3 a    is a side section view of metallic sheet securement with a laser according to an embodiment; 
         FIG. 3 b    is a side section view of the metallic sheet securement of  FIG. 3 a    with a flow fastener according to an embodiment; 
         FIG. 4 a    is a side section view of metallic sheet securement with a laser according to an embodiment; 
         FIG. 4 b    is a side section view of the metallic sheet securement of  FIG. 4 a    with a flow fastener according to an embodiment; 
         FIG. 5 a    is a side section view of metallic sheet securement with a laser according to an embodiment; 
         FIG. 5 b    is a side section view of the metallic sheet securement of  FIG. 5 a    with a flow fastener according to an embodiment; 
         FIG. 6 a    is a side section view of metallic sheet securement with a laser according to an embodiment; 
         FIG. 6 b    is a side section view of the metallic sheet securement of  FIG. 6 a    with a flow fastener according to an embodiment; 
         FIG. 7 a    is a side section view of metallic sheet securement with a laser according to an embodiment; 
         FIG. 7 b    is a side section view of the metallic sheet securement of  FIG. 7 a    with a flow fastener according to an embodiment; 
         FIG. 8 a    is a side section view of metallic sheet securement with a laser according to an embodiment; 
         FIG. 8 b    is a side section view of the metallic sheet securement of  FIG. 8 a    with a flow fastener according to an embodiment; 
         FIG. 9  is a side perspective view of a flow fastener according to an embodiment; 
         FIG. 10  is a side perspective view of a flow fastener according to another embodiment; 
         FIG. 11  is a partial front elevation view of a flow fastener driver of the apparatus of  FIG. 1 ; 
         FIG. 12  is a partial right side elevation view of the flow fastener driver of  FIG. 11 ; 
         FIG. 13  is a partial left side elevation view of the flow fastener driver of  FIG. 11 ; 
         FIG. 14  is a top view of the flow fastener driver of  FIG. 11 ; 
         FIG. 15  is a front elevation view of the flow fastener driver of  FIG. 11 ; 
         FIG. 16  is a left side elevation view of a tooling assembly of the apparatus of  FIG. 1  according to an embodiment; 
         FIG. 17  is front elevation view of the tooling assembly of  FIG. 16 ; 
         FIG. 18  is a left side elevation view of a tooling assembly of the apparatus of  FIG. 1  according to another embodiment, illustrated in a raised position; 
         FIG. 19  is a left side elevation view of the tooling assembly of  FIG. 18 , illustrated in a lowered position; 
         FIG. 20  is a front elevation view of the tooling assembly of  FIG. 18 ; 
         FIG. 21  is a partial front, side perspective view of a light-safe guard assembly of the tooling assemblies  FIGS. 16-20 , according to an embodiment, illustrated in an open position; 
         FIG. 22  is a front, perspective view of the light-safe guard assembly of  FIG. 21 , illustrated in the open position; 
         FIG. 23  is a front, perspective view of the light-safe guard assembly of  FIG. 21 , illustrated in a closed position; 
         FIG. 24  is a right side perspective view of the light-safe guard assembly of  FIG. 21 , illustrated in the closed position; 
         FIG. 25  is a bottom view of the light-safe guard assembly of  FIG. 21 , illustrated in the closed position; 
         FIG. 26  is a bottom view of the light-safe guard assembly of  FIG. 21 , illustrated in the open position; 
         FIG. 27  is a partial front perspective view of the tooling assembly of  FIG. 18 , illustrating the light-safe guard assembly of  FIG. 1  in the closed position; and 
         FIG. 28  is a side perspective section view of metallic securement with a flow fastener according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. 
     An apparatus is generally indicated by  20  and illustrated in  FIGS. 1 and 11-27  to provide metallic sheet securement as also illustrated by  FIGS. 2 a  and 2 b , 3 a  and 3 b , 4 a  and 4 b , 5 a  and 5 b , 6 a  and 6 b , 7 a    and  7   b ,  8   a  and  8   b ,  9 ,  10 , and  28 . Both the apparatus and method of various embodiments is described below in an integrated manner to facilitate an understanding of various features. 
     Advanced high strength steel (AHSS) involved with the securement of metallic sheets according to an embodiment has a tensile strength of 700 megapascals up to 2,000 megapascals (A/Pa) or more. As such, advanced high strength steel sheets have particular utility for use in vehicle body manufacturing such as with underbody components, side components, roof pillars, and roof constructions with a relatively thin gauge and thus lightweight construction that enhances vehicle fuel efficiency while still having structural strength. However, such advanced high strength steel sheets are hard and not sufficiently ductile for forming. Additionally, these advanced high strength steel sheets are too hard to be drilled and tapped by conventional machining. For example, installation of a flow fastener into materials with a tensile strength over 980 megapascals causes failures to the fasteners. 
     As illustrated in  FIG. 1 , a robot, generally indicated by  22 , includes a movable arm  24  that supports a laser system  26  for securing a first metallic sheet  28  and a second metallic sheet  30 , at least one of which is made of advanced high strength steel. The securement is by flow fasteners  31  which may be either a flow form screw  32  as shown in  FIG. 9  with helical threads  34  that allow unthreading of the screw, or a flow push screw  36  as shown in  FIG. 10  with round rings  38  that provide a fastener that cannot be removed by unthreading after securement as is hereinafter described. Of course, any flow fastener may be employed. The prior art has installed flow fasteners by applying torque and pressure to the fastener to heat the workpiece through friction, and consequently to pierce and fasten the fastener to the workpiece. 
     The laser system  26  is constructed to selectively provide either a downwardly projected light-safe laser beam  40  as is hereinafter described in connection with  FIGS. 11-15  or to selectively provide an upwardly directed light-safe laser beam  42  in the manner provided by Savoy et al., U.S. Pat. No. 9,815,109 B2, which issued to Utica Enterprises, Inc., on Nov. 14, 2017, the entire disclosure of which is hereby incorporated by reference. For versatility, only the downwardly projected light-safe laser beam  40  may be provided, only the upwardly directed light-safe beam  42  may be provided, or both the downwardly and upwardly directed light-safe laser beams  40  and  42  may be provided, depending upon metallic sheets being secured to each other. The laser beams  40  and  42  may be employed to heat materials with high tensile strengths, whereby friction heating is insufficient to pierce, tap and/or fasten the fastener. 
     Each of the  FIGS. 2-8  with the subscript “a” illustrates the manner in which laser heating is performed by one or more associated light-safe laser beams and each of the  FIGS. 2-8  with a subscript “b” illustrates the manner in which one of the flow fasteners  31  illustrated in  FIGS. 9 and 10  secures the metallic sheets after the light-safe laser heating. 
     With reference to  FIG. 2 a   , first and second metallic sheets  28  and  30  of advanced high strength steel each have a joining location  44  that is heated by a downwardly directed light-safe laser beam  40  for securement by a flow fastener  31  as shown in  FIG. 2   b.    
     In  FIG. 3 a   , the metallic sheet  28  has a hole  46  through which the downwardly projected light-safe laser beam  40  heats the joining location  44  of the metallic sheet  30  of advanced high strength steel to permit the flow fastener  31  to secure the two metallic sheets to each other as shown in  FIG. 3   b.    
     In  FIG. 4 a   , the metallic sheet  28  is advanced high strength steel with the joining location  44  that is heated by a downwardly directed light-safe laser beam  40  while the metallic sheet  30  is mild steel or aluminum which may or may not be heated to a limited extent by the laser beam passing through the metallic sheet  28  while still permitting securement of the two metallic sheets to each other by the flow fastener  31  shown in  FIG. 4   b.    
     In  FIG. 5 a   , both the metallic sheet  28  and the metallic sheet  30  are advanced high strength steel whose joining locations  44  are both heated by an upwardly directed light-safe laser beam  42  in order to permit the flow fastener  31  to provide the securement shown in  FIG. 5   b.    
     In  FIG. 6 a   , the metallic sheet  28  is mild steel or aluminum and is imperforate while the metallic sheet  30  is advanced high strength steel whose joining location  44  is heated by the upwardly directed light-safe laser beam  42  in order to permit the securement of these metallic sheets by the flow fastener  31  shown in  FIG. 6   b.    
       FIGS. 7 a  and 8 a    illustrate how three or more of the metallic sheets  28  and  30  of advanced high strength steel are heated by the downwardly and upwardly directed light-safe laser beams  40  and  42  with additional sandwiched metallic layers  48  and  50 , etc. between the outer layers so as to permit the securement by the flow fasteners  31  as illustrated in  FIGS. 7 b  and 8 b   . The intermediate metallic sheet(s)  48  and/or  50  may be mild steel, aluminum, advanced high strength steel or combinations of these three metals. 
     The laser system  26  shown in  FIG. 1  has a laser collimator  50  for projecting laser beam  40  through a light-safe path of a housing  52  and the housing also supplies the flow fasteners  31  previously described by the structure indicated in  FIGS. 11-15  for the metallic sheet securement after the laser heating as described above. The structure involved includes a flow fastener driver  54  that provides insertion by rotation and/or pushing of the flow fasteners  31  in a cyclical manner with operation of the robot  22  moving the laser system  26  on the robot arm  24  to different locations for the sheet metal securement. A laser guard  56  including an insulator  58  has a downwardly opening shape that contacts to upper most metallic sheet  28  to contain the laser beam  40 . A suitable sensor senses for such contact and only permits projection of the laser beam upon the contact to provide the light-safe operation. 
     The housing  52  of laser system  26  is C-shaped with a first end  60  and a second end  62  that are spaced from each other as shown in  FIG. 1  to define a workspace  64  in which the light-safe laser heating and metallic sheet securement is performed. 
     A controller  66  shown in  FIG. 1  operates the robot  22  to control all of its movements and operations including only permitting the laser beams  40  and/or  42  to be projected when there is a light-safe contact of the laser system with the metallic sheet(s)  28  and/or  30  is sensed so no laser beam can escape. 
       FIGS. 16 and 17  illustrate an end effector  70  according to another embodiment. The end effector  70  includes a housing  72 . The housing  72  is sized to be mounted to equipment for presentation to a workpiece. For example, the end effector  70  may be mounted to equipment for automation to present a workpiece to the end effector  70 . Likewise, the supportive equipment may also be automated to engage and operate upon the workpiece. Akin to prior embodiments, the end effector  70  may be employed as a robotic end of arm tooling mounted to the arm of a multiple axis flexible automation robot for programmable automation of operation on various workpieces at various orientations. 
     The end effector  70  includes a collimator  74  for heating a workpiece with a laser in order to soften the surface of the workpiece before introduction of a flow screw. The end effector  70  also includes a driver  76 . The driver  76  is employed to push and translate, while rotating with torque, flow form screws  32  into workpieces. The driver  76  is also employed to push and translate flow push screws  36  into workpieces. Alternatively, the collimator  74  may be angled to share a target work location with the driver  76  to heat and fasten a common surface of the workpiece, as illustrated in the next embodiment. The collimator  74  and the driver  76  can be utilized to operate on a top surface of the workpiece according to one example. By approaching and fastening a top surface only of a workpiece, the end effector  70  can reach various locations where a top and bottom approach may not both be accessible. The end effector  70  also includes a feed system  78  with a guide and feed tube to intermittently and sequentially deliver fasteners to the driver  76  for repeated fastening operations. The feed system  78  is controlled to time the delivery of a fastener such that the fastener can be delivered to the workpiece immediately after the heating of the workpiece in order to install the fastener while the workpiece is still heated, and to increase productivity. 
     The end effector  70  also includes a light-safe guard assembly  80  to contain the laser during the heating process. Fastener securement in various high strength metal applications often presents a workpiece with a contoured shape and often has various obstacles. Therefore, providing the end effector  70  with compact tooling due the coordinated collimator  74  and the driver  76  with the compact guard assembly  80  permits the end effector  70  to install fasteners  32 ,  36  at various locations. The light-safe guard assembly  80  is illustrated and described in greater detail below in  FIGS. 21-27 . 
     The end effector  70  is effective for installing the fasteners  32 ,  36  to multiple sheets of material when the top surface is an AHSS material that requires heating before installation, and the underlying layer is a soft material. The end effector  70  can also be employed to heat a soft metal top layer and an AHSS underlying layer. The end effector  70  can also heat an underlying AHSS layer through a clearance hole formed in one or more upper layers. Multiple AHSS layers can be fastened together by providing clearance apertures in one or more upper AHSS layers. 
       FIGS. 18-20  illustrate an end effector  82  according to another embodiment. The end effector  82  includes an upper housing  84  for mounting the end effector  82  to equipment, such as a robot. The end effector  82  includes an upper collimator  86  for heating an upper workpiece similar to the prior embodiment. The end effector  82  also includes a driver  88  for driving the fasteners  32 ,  36  into workpieces. The collimator  86  is angled to share a target work location with the driver  88  to heat and fasten a common surface of the workpiece. The end effector  82  also includes a feed system  90  with a guide and feed tube to intermittently and sequentially deliver fasteners to the driver  88 . The end effector  82  also includes a light-safe guard assembly  80  to contain the laser during the heating process. 
     The end effector  82  includes a lower housing  92  that supports a lower collimator  94  to heat a lower workpiece with a laser for installation of the fastener  32 ,  36  from the driver  88 . The lower collimator may be provided with a laser collimator  94  as disclosed in Savoy et al., U.S. Pat. No. 9,815,109 B2, which issued to Utica Enterprises, Inc., on Nov. 14, 2017, the disclosure of which is incorporated by reference. 
     The upper housing  84  and the lower housing  92  include distal ends to operate on the workpieces, which are spaced apart from each other and facing each other to operate on aligned upper and lower surfaces of the workpieces. The lower housing  92  is connected to the upper housing  84  upon a track  96  which includes a guide and a linear actuator for translation of the lower housing  92  relative to the upper housing  84 . A raised position of the lower housing  92  is depicted in  FIG. 18 ; and a lowered position of the lower housing  92  is depicted in  FIG. 19 . Translation of the lower housing  92  accommodates workpieces of varying thicknesses and combinations of workpieces of varying thicknesses. Additionally, a workpiece may employ a fastener adjacent to an obstacle, such as a bend in the sheet metal, whereby the lower housing  92  may be lowered for clearance at approach, raised for operation, and lowered again for clearance while retracting the tooling. 
     The end effector  82  permits the fasteners  32 ,  36  to be driven into multiple sheets of AHSS by heating upper and lower sheets prior to installation of the fasteners. Alternatively, if only a lower sheet is AHSS, then the upper collimator  86  may be unused, or omitted altogether. 
       FIGS. 21-27  illustrate the light-safe guard assembly  80  in greater detail. The light-safe guard assembly  80  includes a contact foot  98  mounted to a bracket  100  on the upper housing  84 . The contact foot  98  extends below the upper housing  84  and contacts the workpiece to apply a pressure to the workpiece to maintain a position of the workpiece during the fastening operation. For example, the contact foot  98  prevents the fastening operation from separating the material sheets from one another during the fastening operation so that a gap is not created within the workpiece. As depicted in the bottom axial end views of  FIGS. 25 and 26 , the contact foot  98  include a recess  102  to provide clearance at a heating and fastening location upon the workpiece. 
     The light-safe guard assembly  80  includes a pair of elongate shroud portions  104 ,  106  to enclose the work location of the workpieces. The shroud portions  104 ,  106  are round and partially tapered and each meet at a lengthwise bisection of a collectively round and hollow cross section. As illustrated in  FIG. 27 , the shroud portions  104 ,  106  are mounted to an actuator  108  for pivoting between an open position depicted in  FIGS. 21, 22 and 26 , to a closed position depicted in  FIGS. 23-25 and 27 . 
     The light-safe guard assembly  80  approaches the work location of the workpieces in the open position ( FIGS. 21, 22 and 26 ) of the shroud portions  104 ,  106 . Once the foot  98  contacts the workpiece, the upper housing  84  is maintained in position, and the actuator  108  closes the shroud portions  104 ,  106 . The shroud portions  104 ,  106  contribute to a light-safe enclosure. Referring to  FIG. 26 , a groove  110  is formed along the bisection line of one of the shroud portions  104 . A seal, such as a gasket  112  is provided along the bisection line of the other shroud portion  106 . Once the shroud portions  104 ,  106  are closed ( FIGS. 23-25 and 27 ), the gaskets  112  engage the grooves  110  and seal the shroud portions  104 ,  106  lengthwise. 
     The light-safe guard assembly  80  includes a pair of arcuate arrays of wire bristles  114 ,  116 . Each array  114 ,  116  includes multiple layers of bristles about concentric arcs. The arrays of bristles  114 ,  116  are each mounted to one of the shroud portions  104 ,  106  by a half collar  118 ,  120 . Each half collar  118 ,  120  is fastened to a distal end of the corresponding shroud portion  104 ,  106  by screws  122  to clamp a proximal end of the bristle array  114 ,  116  to the corresponding shroud portion  104 ,  106 . The bristle arrays  114 ,  116  include recesses  124 ,  126  for clearance of the contact foot  98  as illustrated in  FIG. 26 . The bristle arrays  114 ,  116  engage the workpiece to provide a flexible contact with the workpiece that is light-safe to contain the laser, while sufficiently flexible to avoid damage to the workpiece. 
     Referring now to  FIG. 27 , an air source line  128  delivers a pressurized air source into an enclosed chamber provided within the shroud portions  104 ,  106  and the bristle arrays  114 ,  116 . An air flow switch  130  measures the air flow or pressure within the work chamber. Once the shroud portions  104 ,  106  are closed, if there is no change in air pressure, then the work chamber is airtight, and consequently light=safe. Based on this condition, the collimator  86  is operated to heat the workpiece. Likewise, if a lower pressure is detected or a continuous air flow is detected, then an air leak is detected, which could potentially permit a breach in light safety. In this detected condition, the collimator  86  is not operated to maintain light safety at the workpiece. 
       FIG. 28  illustrates a plurality of flow form screws  32  installed into workpieces  132 . One of the workpieces  132  is illustrated with a flow form screw  32  removed, thereby demonstrating a resultant threaded aperture  134  that is formed into the workpiece  132  as the workpiece  132  cools. Therefore, the flow form screw  32  can be removed for repair and replacement of components that are installed and/assembled with flow form screws  32 . 
     While various embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.