Apparatus and method for securing a clinch nut to a sheet of advanced high strength steel and resultant assembly

Abstract

Apparatus ( 20 ) and a method for securing a clinch nut ( 24 ) to an AHSS sheet ( 26 ) as an assembly ( 22 ). In one embodiment, a parallel kinematic machine (PKM) ( 88 ) sequentially performs the operation, while another embodiment includes a nut ram assembly ( 112 ) that attaches clinch nuts ( 24 ) to the AHSS sheet ( 26 ), and a further embodiment includes a C frame ( 114 ) that supports the apparatus and is moved by a robot ( 130 ) to sequentially attach clinch nuts ( 24 ) to the AHSS sheet ( 26 ) at different locations. The attachment of the clinch nuts is performed in a light-safe manner.

What is claimed is: 
     
         1 . Apparatus for securing a clinch nut to a sheet of AHSS comprising:
 a joining assembly adjacent which the AHSS sheet is positioned;   the joining assembly including a base and an indexing member mounted on the base for movement parallel to the AHSS sheet; and the indexing member having a heating opening and a clinch die spaced from each other along a direction parallel to the AHSS sheet;   an actuator that moves the indexing member between a heating position where its heating opening is located at a work location of the AHSS sheet and a joining position where its clinch die is located at the work location of the AHSS sheet;   a laser assembly for firing a laser beam through the heating opening of the indexing member while in the heating position to provide heating of the work location of the AHSS sheet;   a nut ram to which clinch nuts, each of which has a threaded hole, are fed, and the nut ram being aligned with the clinch die when the indexing member is in the joining position to attach a clinch nut to the AHSS sheet at the heated work location of the AHSS sheet so a threaded fastener can be connected to the AHSS sheet; and   a controller configured to operate the joining assembly and the nut ram.   
     
     
         2 . Apparatus for securing a clinch nut to a sheet of AHSS as in  claim 1  wherein the joining assembly includes an enclosure defining a light-safe chamber partially defined by the base and from which the laser assembly fires the laser beam through an opening in the base and thence through the heating opening in the indexing member while in the heating position to provide the heating of the work location of the AHSS sheet, and a detector assembly operated by the controller to only permit operation of the laser assembly when the AHSS sheet is in light-safe contact with the indexing member around its heating opening when the indexing member is in the heating position. 
     
     
         3 . Apparatus for securing a clinch nut to a sheet of AHSS as in  claim 2  wherein the detector assembly includes a source of pressurized gas for providing pressurized gas to the chamber and also includes a detector for detecting gas flow from the source through the chamber to detect whether the AHSS sheet is in light-safe contact with the indexing member around its heating opening. 
     
     
         4 . Apparatus for securing a clinch nut to a sheet of AHSS as in  claim 1  wherein pierce clinch nuts are fed to the nut ram for attaching to the AHSS sheet. 
     
     
         5 . Apparatus for securing a clinch nut to a sheet of AHSS as in  claim 1  which includes either: a slideway that mounts the indexing member on the base for rectilinear movement by the actuator between the heating position and the joining position or a pivotal connection that mounts the indexing member on the base for pivotal movement by the actuator between the heating position and the joining position. 
     
     
         6 . Apparatus for securing a clinch nut to a sheet of AHSS as in  claim 1  further including a temperature sensor for sensing the temperature of the AHSS sheet at the work location of the AHSS sheet. 
     
     
         7 . Apparatus for securing a clinch nut to a sheet of AHSS as in  claim 1  which includes a plurality of the joining assemblies spaced from each other and operated by the controller; and a parallel kinematic machine (PKM) operated by the controller and including: a first support; a tripod having three extendable and retractable struts mounted and extending away from the first support in a converging manner toward each other; a second support mounted by the three struts spaced from the first support to mount the nut ram that aligns with the clinch die under the operation of the controller to provide the attachment of clinch nuts to the AHSS sheet; and perpendicular rails that mount the PKM for movement in horizontal directions that are perpendicular to each other to cooperate with the joining assemblies to provide attachments of clinch nuts to the sheet at different locations. 
     
     
         8 . Apparatus for securing a clinch nut to a sheet of AHSS as in  claim 1  which includes a floor and a framework having an upper beam spaced above the floor, and the joining assembly and nut ram being located and operated between the floor and upper beam of the framework. 
     
     
         9 . Apparatus for securing a clinch nut to a sheet of AHSS as in  claim 8  wherein the joining assembly is supported on the floor below the AHSS sheet and the nut ram is supported by the upper beam of the framework above the AHSS sheet. 
     
     
         10 . Apparatus for securing a clinch nut to a sheet of AHSS as in  claim 8  which includes a plurality of the joining assemblies mounted on the floor spaced from each other and operated by the controller; and a nut ram assembly that mounts a plurality of the nut rams under the operation of the controller to cooperate with the joining assemblies to simultaneously provide attachments of clinch nuts to the AHSS sheet at different locations. 
     
     
         11 . Apparatus for securing a clinch nut to a sheet of AHSS as in  claim 1  which includes a C frame having one end that supports the joining assembly and having another end that supports the nut ram that cooperates with the clinch die under the operation of the controller to provide the attachments of the clinch nuts to the AHSS sheet, and a robot that moves the C frame under operation of the controller to provide attachments of the clinch nuts to the AHSS sheet at different locations. 
     
     
         12 . A method for securing a clinch nut to a sheet of AHSS comprising:
 positioning an AHSS sheet adjacent a joining assembly including an indexing member movable parallel to the AHSS sheet and having a heating opening and a clinch die spaced from each other along a direction parallel to the AHSS sheet;   firing a laser beam through the heating opening of the indexing member at a heating position thereof to heat a work location of the AHSS sheet;   moving the indexing member parallel to the AHSS sheet to a joining position where its clinch die is aligned with the work location of the AHSS sheet; and   using a controller to operate a nut ram to which clinch nuts, each of which has a threaded opening, are fed to align with the clinch die when the indexing member is in the joining position to attach a clinch nut to the AHSS sheet at its heated work location so a threaded fastener can be connected to the clinch nut.   
     
     
         13 . A method for securing a clinch nut to a sheet of AHSS as in  claim 12  wherein the laser beam is fired from within a light-safe chamber through an opening in a chamber and thence through the heating opening of the indexing member while in the heating position to provide the heating of the work location of the AHSS sheet, and wherein the laser beam firing is only permitted by the controller when presence of the AHSS sheet is detected closing the heating opening of the indexing member around its heating opening with light-safe contact. 
     
     
         14 . A method for securing a clinch nut to a sheet of AHSS as in  claim 12  wherein pressurized gas flow through the light-safe chamber is sensed to detect whether the AHSS sheet is contacting the indexing member to a light-safe extent around its heating opening to control operation of the laser beam by the controller. 
     
     
         15 . A method for securing a clinch nut to a sheet of AHSS as in  claim 12  wherein pierce clinch nuts are fed to the nut ram. 
     
     
         16 . A method for securing a clinch nut to a sheet of AHSS as in  claim 12  wherein the indexing member is either moved in a rectilinear manner between the heating position and the joining position or pivotally moved between the heating position and the joining position. 
     
     
         17 . A method for securing a clinch nut to a sheet of AHSS as in  claim 12  wherein the temperature of the AHSS sheet is sensed at its work location from above or below the AHSS sheet. 
     
     
         18 . A method for securing a clinch nut to a sheet of AHSS as in  claim 12  wherein: the controller operates a plurality of the joining assemblies spaced from each other; the controller also operates a parallel kinematic machine (PKM) including: a first support; a tripod having three extendable and retractable struts mounted and extending away from the first support in a converging manner toward each other; and a second support mounted by the three struts spaced from the first support to mount the nut ram that cooperates with the clinch die under the operation of the controller to provide the attachment of the clinch nut to the AHSS sheet; and wherein perpendicular rails mount the PKM for movement under its operation of the controller in horizontal directions that are perpendicular to each other to cooperate with the joining assemblies to provide attaching of pierce clinch nuts to the AHSS sheet at different locations. 
     
     
         19 . A method for securing a clinch nut to a sheet of AHSS as in  claim 12  wherein the joining assembly and the nut ram are operated between a floor and an upper beam of a framework mounted on the floor. 
     
     
         20 . A method for securing a clinch nut to a sheet of AHSS as in  claim 17  wherein the joining assembly is operated below the AHSS sheet and the nut ram is operated above the AHSS sheet. 
     
     
         21 . A method for securing a clinch nut to a sheet of AHSS as in  claim 12  wherein the controller operates a plurality of the joining assemblies mounted on the floor spaced from each other; and a nut ram assembly mounts a plurality of the nut rams and under the operation of the controller cooperates with the joining assemblies to simultaneously provide attaching of pierce clinch nuts to the AHSS sheet at different locations. 
     
     
         22 . A method for securing a clinch nut to a sheet of AHSS as in  claim 12  wherein one end of a C frame supports the joining assembly and another end of the C frame supports the nut ram that cooperates with the clinch die under the operation of the controller to provide attaching of a clinch nut to the AHSS sheet, and wherein a robot moves the C frame under operation of the controller to provide the attaching of the clinch nut to the AHSS sheet at different locations. 
     
     
         23 . An assembly comprising;
 a sheet of AHSS; and   a pierce clinch nut attached at a heated work location to a hole pierced by an extended pierce form of the pierce clinch nut through the AHSS sheet with attachment provided by a clinch interlock from a flow of the sheet of AHSS at the heated work location into an undercut in the pierce clinch nut.   
     
     
         24 . The assembly of  claim 23  wherein the sheet of AHSS has a tensile strength of at least 700 Megapascal. 
     
     
         25 . The assembly of  claim 24  wherein the sheet of AHSS has a thickness of at least 0.7 millimeter. 
     
     
         26 . The assembly of  claim 24  wherein the sheet of AHSS has a thickness of 0.7 to two millimeters.