Abstract:
A system installs an insert within an aperture in a workpiece, the workpiece having a first side and a second side. The insert is the type in which a portion of the insert plastically deforms on the second side of the workpiece upon application of a linear force provided by a rotating tool, thereby preventing withdrawal of the insert from the aperture. The insert comprises a sleeve member and an integral flange, where the flange has a larger diameter than the aperture. The disclosed installation system performs two actions. It causes the expansion of the sleeve and it also causes the flange of the insert to be fused or welded to the first side of the workpiece. The welded connection between the insert and the workpiece prevents any rotation or spinning of the insert within the workpiece, and increases the integrity of the insert-fastener connection.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    U.S. Provisional Application No. 60/798,281 for this invention was filed on May 4, 2006 for which the inventor claims domestic priority. 
     
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to an apparatus and method for attaching nut inserts to a workpiece, the workpiece having a first side and a second. Usually the first side is a visible side and the second side is a blind side, meaning there is no access to the second side. More particularly, this invention relates to an installation system which is capable of expanding the body of the insert such that the insert cannot be withdrawn from an aperture within the workpiece, while, nearly simultaneous to the expanding of the body of the insert, the system fuses the insert to the work piece, through a fusing process such as resistance welding, drawn arc welding, or capacitor discharge welding. 
         [0003]    It is known to use threaded rivet nuts, threaded inserts, and threadable inserts, as anchors for threaded fasteners in a number of different applications, including thin wall applications, such as sheet metal, which may be too thin to be tapped with threads. In many such cases there is access only to one side of the workpiece. In general, the workpiece is drilled or punched and the anchor device is placed within the resulting hole by an installation tool. When the installation tool is activated, a portion of the anchor device on the blind side of the workpiece, such as a sleeve portion, is deformed to create an enlargement or bubble which prevents removal of the insert from the hole. After the installation tool is disengaged, a threaded fastener may be inserted into a threaded portion of the insert. 
         [0004]    Installation tools for setting nut inserts, particularly in blind applications, are generally known. These tools generally comprise a tool body from which extends a mandrel having external threads. The mandrel typically extends through a nose piece which is connected to the front of the tool body. In one variety of tool, rotational means are operationally connected to the rear of the mandrel for rotating the threaded mandrel to make up the threaded mandrel within the nut insert prior to deformation of the sleeve portion. The threads of the mandrel are made up into the threads of the nut insert until a flange on the end of the insert abuts the front end surface of the nose piece. If not already placed within an aperture of the work piece, the insert is thereafter placed within the aperture until the flange abuts the first side of the workpiece. Rotation of the mandrel is continued, the torque applied to the mandrel converted to linear force. 
         [0005]    The application of the linear force to the insert collapses the sleeve portion of the insert which is on the second side of the workpiece such that the resulting enlargement or bubble is larger than the diameter of the aperture, preventing withdrawal of the insert from the aperture. The installation tools generally comprise a tool body from which extends a stud member having external threads. Rotational means are connected to the rear of the stud member, for rotating the stud member. The stud member typically extends through a nose piece which is connected to the front of the tool body. An insert is screwed onto the external threads of the stud member, and the stud member made up into the insert until a flange on the end of the insert abuts the front end surface of the nose piece. The insert is placed within an aperture in the workpiece until the flange abuts the first side of the workpiece. The rotational means are then activated, thereby causing the external threads of the stud member to make up into the threads of the insert, thereby causing the threaded portion of the insert to move along the threads of the stud member, causing the sleeve of the insert to plastically deform to form an expanded portion. The expanded portion, sometimes referred to as the “bubble”, is larger than the diameter of the aperture, preventing withdrawal of the insert from the aperture. An example of such a tool may be found in U.S. Pat. No. 4,321,814. 
         [0006]    It is desirable that the anchor device resist spinning or rotating within the aperture in the workpiece. One known means of preventing rotation of the anchor device within the hole of the workpiece is to make the hole in a shape other than round, such as octagonal, and to use an insert having a sleeve which has a corresponding shape, such that the sleeve is locked within the hole to prevent rotation, as the corners of the sleeve lock into corresponding corners of the hole. However, installing non-round openings in the workpiece and manufacturing inserts having other than a round shape is more costly than installing round openings in the workpiece and manufacturing round inserts. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is directed to an insert installation system and method which meet the needs identified above. The disclosed apparatus is a system for installing an insert within an aperture in a workpiece, the workpiece having a first side and a second side. The insert is the type in which a portion of the insert plastically deforms on the second side of the workpiece upon application of a linear force provided by a torque-applying rotational tool, thereby preventing withdrawal of the insert from the aperture. The insert comprises a sleeve member and an integral flange, where the flange has a larger diameter than the aperture. 
         [0008]    The disclosed installation system performs two actions. It causes the expansion of the sleeve and it also causes the flange of the insert to be fused or welded to the workpiece. The welded connection between the insert and the workpiece prevents any rotation or spinning of the insert within the workpiece, and increases the integrity of the insert-fastener connection. 
         [0009]    The system comprises a tool body with a nose piece attached to the front of the tool body. Insert attachment means extend through the nose piece of the tool body. Rotation means contained within the tool body are connected to the insert attachment means, which, by the rotation of the insert attachment means, applies a torque-induced linear force to the insert, causing the sleeve of the insert to expand, or plastically deform, as the insert attachment means is rotated. 
         [0010]    A first electrode is attached to the nose piece. The system further comprises a second electrode for connecting to the workpiece. Current generation means are connected to the first electrode and the second electrode for creating an electrical current between the first electrode and the second electrode. The system comprises activation means for activating the rotation means and the current generation means. 
         [0011]    Typically, a portion of the tool body, such as a threaded stud, provides the insert attachment means. The insert attachment means engages the sleeve member of the insert, such as by making up the threaded stud into internal threads within the sleeve of the insert. The insert is then placed within the aperture until the flange of the insert abuts the first side of the work piece, and the face of the nose piece abuts the flange on the other side. Upon activation, the rotation means connected to the insert attachment means cause the insert attachment means to rotate. As the insert attachment means are rotated, a linear force is applied to the tubular sleeve of the insert on the blind side of the workpiece as the threaded portion of the insert is pulled axially along the threads of the threaded stud. The linear force plastically deforms a portion of the sleeve into a bubble or secondary flange larger than the diameter of the hole in the workpiece. The rotation is continued until the motor of the rotation means either stalls or slows, indicating that the blind fastener has collapsed, forming the bubble. This bubble prevents withdrawal of the insert from the hole. The current generation means is activated either before or after formation of the bubble, fusing the insert to the workpiece. 
         [0012]    These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a side view of one variety of the disclosed installation system, shown installing a threaded insert into a workpiece. 
           [0014]      FIG. 2  is an exploded view generally depicting the components of a rotational type of installation tool. 
           [0015]      FIG. 3  shows a schematic view of one embodiment of a nose piece which may be utilized with the disclosed installation system. 
           [0016]      FIG. 4  is a perspective view of an embodiment of an insert which may be used with the disclosed installation system, shown prior to installation of the insert. 
           [0017]      FIG. 5  shows a quarter sectional view of an embodiment of a threaded insert after being compressed and welded to the workpiece. 
           [0018]      FIG. 6  shows a perspective view of an embodiment of a threaded insert which may be used with the disclosed installation system, showing the internal threads of the insert and the underside of the flange. 
           [0019]      FIG. 7  shows a perspective view of the embodiment show in  FIG. 6 , viewed from the top of the flange. 
           [0020]      FIG. 8  shows a perspective view of another embodiment of a threaded insert which may be used with the disclosed installation system, showing the internal threads of the insert and the underside of the flange. 
           [0021]      FIG. 9  shows a perspective view of the embodiment show in  FIG. 8 , viewed from the top of the flange. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0022]    Referring now specifically to the drawings,  FIG. 1  shows one embodiment of the installation system  10  installing an insert  12  to a workpiece  14 . The installation system comprises a tool body  16 . The tool body  16  comprises a housing  18  and a motor section  20 . The motor section  20  may comprise motor  23 , which may be pneumatically driven or driven by means known in the art, such as by electricity or hydraulically. Hereinafter, the uninstalled insert is referred to herein as  12  and the installed insert is referred to herein as  12 ′. 
         [0023]    The tool body  16  may be in the configuration of a gun, as shown in  FIG. 1 , for handling ease and convenience. A nose piece  22  is attached to the housing  18 . The insert  12  is connected to insert attachment means, such as threaded stud  24 . If a threaded stud  24  is used as the insert attachment means, the threaded stud engages internal threads  26  of the insert  12 . The motor  23  or other rotation means contained within the motor section  20 , acts to rotate the threaded stud  24 . The air motor  23  allows the user to quickly make up the threaded stud  24  into the internal threads  26  of the insert  12 , where the threaded stud is inserted into the end of the insert having flange  32 . The air motor  23 , or other means of rotation, allows the user to quickly back the threaded stud  24  out of the internal threads  26  of the set insert  12  shown in  FIG. 5 . 
         [0024]    As the threaded stud  24  is rotated into threads  26  of the non-rotating insert  12 , a torque-induced linear force is applied to the tubular sleeve  34  of the insert  12  on the blind side  36  of the workpiece  14 , axially pulling the nut portion of the insert along the threads of the threaded stud, thereby collapsing by plastic deformation a portion of the sleeve into a bubble  38  or secondary flange larger than the diameter of the hole in the workpiece. The rotation is continued until the motor  23  or other rotation means either stalls or slows, indicating that the blind fastener has collapsed, forming the bubble  38 .  FIG. 5  shows an insert  12 ′ after it has been installed in workpiece  14  and the bubble  38  has been formed on the second side  36  of the workpiece  14 . 
         [0025]    As further shown in  FIG. 1 , a first electrode  40  is attached to nose piece  22  with fastening means, such as a bolt made up into matching threads in the nose piece. A second electrode  42  may connected to the workpiece  14  with attachment means, such as the clamp shown in  FIG. 1 , which allow the second electrode to be quickly connected and released from the workpiece. The first electrode  40  and second electrode  42  are connected at their respective opposite ends to current generation means  44 . The current generation means  44  may be activated nearly simultaneously with the activation of the rotation means, or activated either before or after activation of the rotation means. The current generation means  44  creates current flow between the first electrode  40  and the second electrode  42 , causing the underside of the flange  32  or other portions of the insert  12  to be fused (i.e., welded) to the workpiece  14 . As shown in  FIG. 5 , the fused connection  43  may be formed between the underside of flange  32  and the front side  45  of the workpiece  14 . Alternatively, the fused connection  43  may be formed between other portions of the insert  12  to the workpiece  14 , such as between tubular sleeve  34  and the aperture of the work piece, or to the second side  36  of the workpiece. 
         [0026]    The current generation means  44  may be those commonly known in the art for welding purposes, such as a welding machine. In particular, resistance welding equipment may be used. One specific variety of resistance welding machine is a capacitor discharge welding machine. Capacitor discharge welding, also sometimes referred to as pulse welding, is a form of resistance welding where the fused connection is achieved within milliseconds at very high current levels by utilizing energy stored in a capacitor battery or bank. In general, in the capacitor discharge welding process, electrodes are attached to the workpieces to be joined, and an extremely short pulse is provided. This very short energy pulse heats the surfaces of both components to be welded to a plastic state, thus avoiding the mixing and creation of undesired alloys at the weld interface. The workpieces generally show no distortion or dimensional changes after the capacitor discharge welding process. Among the other known welding processes, capacitor discharge welding has the advantage that the welding machine is a relatively small unit which fits on a table top or portable stand and is fairly easy to transport. 
         [0027]    The rotation means may be powered by pneumatic control means, such as air compressor  46 . Some installation tools use air pressure from an air compressor to drive air motor  23  within the tool for operating the rotation means. The installation system further comprises activation means for activating the rotation means and the current generation means  44 . As shown in  FIG. 1 , the activation means may comprise a trigger  48  attached to the motor section  20 . The trigger  48  may directly engage the rotation means, as known for existing insert installation tools, by activating a valve and allowing air flow into the tool body  16 . Alternatively, the trigger  48  may comprise an electrical contact which either opens or closes (i.e., “activated”) upon manipulation of the trigger. The installation system may further comprise processing means, such as a programable controller  50  which is capable of receiving input signals and generating output signals. Trigger  48  may be electrically connected to the programable controller  50 , such that activation of the trigger and opening or closing of the electrical contact initiates a command sequence by the programable controller  50  with output signals being provided to various end devices. For example, upon activation of the trigger  48 , the programable controller  50  might provide an output signal to the pneumatic control means, such as air compressor  46 , to provide air pressure to the rotation means, thereby causing the sleeve  34  of insert  12  to be plastically deformed to form bubble  38 . Following a designated time interval, the programable controller  50  may then provide an output signal to current generation means  44 , causing a current to be applied between the first electrode  40  and the second electrode  42 , causing the insert  12  to be fused to the workpiece  14 . Of course, this sequence may be reversed by simple changes in the logic of the programable controller  50 . 
         [0028]    Alternatively, the installation system may comprise separate activation means respectively for the pneumatic control means and the current generation means. For example, a first trigger  48   a  may be attached to the tool body  16  which activates the rotation means and a second trigger  48   b  attached to the tool body which activates the current generation means  44 . First trigger  48   a  and second trigger  48   b  may each respectively comprise a first electrical contact and a second electrical contact, each which either opens or closes upon manipulation of each of the triggers. The first electrical contact may then be electrically connected to the pneumatic control means, such that the pneumatic control means is activated when the first electrical contact is activated by manipulation of the trigger. Similarly, the second electrical contact may electrically connected to the current generation means  44 , such that the current generation means is activated when the second electrical contact is either opened or closed upon manipulation of the trigger. It is to be appreciated that first trigger  48   a  and second trigger  48   b  may comprise a single dual-action trigger, which is activated by pressing a trigger member at different locations on the member. For example, the first trigger  48   a  may be activated by pulling at the bottom of the member and the second trigger  48   b  may be activated by pulling at the top of the member, or vice-versa. It is also possible that the first trigger  48   a  may operate an air valve while second trigger  48   b  operates an electrical contact, or first trigger  48   a  may operate an electrical contact while second trigger  48   b  operates an air valve. 
         [0029]    As shown schematically in  FIG. 3 , the nose piece  22  may have different members or segments, such as a rear member  52  adjacent to the housing  18  (not shown in  FIG. 3 ), an intermediate member  54  adjacent to the rear member, and a front member  56  adjacent to the intermediate member. The first electrode  40  is then attached to the front member  56  with fastening means, such a bolt and matching threads  55  tapped in the front member. The intermediate member  54  comprises an insulation material, which may comprise DELRIN® or other thermoplastic material. The rear member  52  may comprise aluminum and the front member  56  comprises a conductive material such as copper or copper alloy adjacent to the intermediate member, the first electrode  40  attached to the front member. 
         [0030]    One insert  12  for use with the disclosed installation system is shown in  FIG. 4 . The insert  12  has one or more protrusions  58  on the underside of flange  32 . When the sleeve  34  of insert  12  is placed within the aperture of the workpiece  14 , the flange  32  is abutted against the first side  45  of the workpiece  14 , such that the flange  32  is sandwiched between the first side  45  on one side and the front member  56  of the nose piece  22  on the other. Upon activation of the current generation means  44 , the protrusions  58  are fused to the first side  45  of the workpiece or to the sidewall of the aperture, forming one or more fused connections  43  between the insert  12  and the workpiece  14 . The fused connection  43  prevents the installed insert  12 ′ from spinning within the workpiece, and provides a more secure anchor for a fastener installed within the insert. 
         [0031]    Different embodiments of inserts may be used, such as insert  112  shown in  FIGS. 6-9 . As shown in  FIG. 6 , insert  112  may comprise flange  132  which comprises dimples  60  which have an extending protrusion on the underside of flange  132 . Upon activation of the current generation means  44 , the protruding portions of dimples  60  are fused to the workpiece  14 , forming one or more fused connections  43  between the insert  112  and the workpiece  14 . Insert  112  may further comprise knurls  62  on tubular sleeve  34 . As shown in  FIG. 7 , a portion of the tubular sleeve  134  adjacent to flange  132  comprises wall section  164  which has a thinner wall than the threaded section of the sleeve. It is wall section  164  which collapses to form the bubble  38 .  FIGS. 8-9  show another embodiment of the insert  212 , which is similar to the embodiment shown in  FIGS. 6-7 , but which does not comprise knurls  62 . 
         [0032]    It is to be appreciated that there are a number of known different insert installation tools, having different internal mechanisms or other features. The present invention may be used with the known insert installation tools by attaching a first electrode  40  to a current conducting nosepiece on the tool. The current generation means may be activated by either modifying the existing trigger of the tool so that it activates the welding machine. As an alternative, the current generation means may be activated by the controls on the unit itself. 
         [0033]    A method of attaching fasteners to a workpiece having a first side and a second, and an existing aperture in the workpiece is also disclosed. One embodiment of the method comprises the steps of attaching the insert  12  to a tool body  16  of the installation system disclosed herein, where the insert is made up to insert attachment means extending from the nose piece  22  of the tool body  16  such that the flange  32  of the insert is adjacent and abutting the nose piece. The second electrode  42  is connected to the workpiece  14 . The insert  12  is inserted into the aperture of the workpiece  14 , such that the inside face of flange  32  is immediately adjacent and touching the first side  45  of the workpiece, and the outside face is adjacent and abutting the front of the nose piece  22  of the tool body  16 . The activation means of the installation system  10  are engaged, whereby a portion of the sleeve  34  on the second side  36  of the workpiece  14  is enlarged by rotation means and the flange  32  is fused to the workpiece  14  by the current generation means  44 . The insert attachment means is thereafter disengaged from the installed insert  12 ′. 
         [0034]    These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings. While the above is a description of various embodiments of the present invention, further modifications may be employed without departing from the spirit and scope of the present invention. For example, the size, shape, and/or material of the various components may be changed as desired. Thus the scope of the invention should not be limited by the specific structures disclosed. Instead the true scope of the invention should be determined by the following claims.