Patent Publication Number: US-7712209-B2

Title: Magnetic rivet retention system for a rivet gun

Description:
RELATED APPLICATION (PRIORITY CLAIM) 
     This application claims the benefit of U.S. Provisional Application Ser. No. 60/652,593, filed Feb. 14, 2005. 
    
    
     BACKGROUND 
     The present invention generally relates to rivet guns, and specifically relates to rivet retention systems for use with rivet guns. 
     Rivet guns, such as hydraulic rivet guns, have a head portion which engages a powered body portion. In the case of a hydraulic rivet gun, a C-frame assembly  10  such as is shown in  FIG. 1  may engage a hydraulic-powered handle (not specifically shown in  FIG. 1 ). The C-frame assembly  10  includes a C-frame body portion  12  which engages the handle, and is secured to the handle using screws  14 . 
     A threaded bolt  16  is provided, and the threaded bolt  16  includes a head portion  18  and a threaded shaft portion  20 . The threaded shaft portion  20  extends through a throughbore  22  which is provided in a back bushing  24  and threadably engages in a front bushing  26 . The back bushing  24  and front bushing  26  are disposed in a chamber  28  which is provided in the C-frame  12 . A compression spring  30  is also disposed in the chamber  28 , generally between the body portion  12  and the handle (not specifically shown in  FIG. 1 ). As such, the rivet gun is hydraulically powered (viz-a-viz the handle) and is spring return (viz-a-viz spring  30 ). 
     The C-frame  10  includes spacing  32  for receiving a workpiece. Proximate the spacing  32  is an opening  34  which is in communication with the chamber  28  in which the front bushing  26  is disposed. An end  36  of the front bushing  26  includes a bore  38  for receiving a back end of a punch (not specifically shown in  FIG. 1 ). Specifically, the back end of the punch extends into the opening  34  in the C-frame  12  and extends into the bore  38  in the end  36  of the front bushing  26 . A set screw  40  secures the back end of the punch and holds the punch in place relative to the front bushing  26 . Proximate the spacing  32  in the C-frame  12  is another opening (not visible in  FIG. 1 ) for receiving an end of a die (not specifically shown in  FIG. 1 ). A set screw  42  is provided to secure the end of the die and hold the die in place relative to the C-frame  12 . 
     In use, a self-piercing rivet is placed inside the punch, and a workpiece is positioned in the spacing  32  provided in the C-frame  12 . Then, the handle of the rivet gun is actuated, causing the punch to move toward the die, causing the rivet to set in the workpiece. After the rivet sets, the punch returns to its starting position via the spring force exerted by spring  30 . 
     A problem which exists with regard to rivet guns, such as a hydraulic rivet gun which uses a C-frame as shown in  FIG. 1 , is the positioning of the rivet in the punch before the gun is actuated. If the rivet is not properly aligned before the rivet gun is actuated, the rivet may not set right during actuation of the rivet gun. To assist in the aligning of rivets, a retaining member (not specifically shown in  FIG. 1 ), such as a urethane ring, may be provided on an end of the punch. However, such retaining members (especially their inside diameters) tend to get worn, thereby losing their effectiveness for precisely positioning rivets. 
     Furthermore, some rivet guns, such as those rivet guns which us a set of jaws to hold a rivet for broaching, are not practical for some applications. For example, some applications, such as roofing applications, provide that a workpiece is multiple-layered, having glue disposed between at least two of the layers. During riveting, glue may squirt onto the rivet gun, thereby diminishing the effectiveness of the gun during subsequent operation. 
     OBJECTS AND SUMMARY 
     An object of an embodiment of the present invention is provide an improved rivet retention system for a rivet gun. 
     Another object of an embodiment of the present invention is provide a magnetic rivet retention system for a rivet gun. 
     Yet another object of an embodiment of the present invention is provide a rivet retention system for a rivet gun, where the effectiveness of the system does not substantially diminish as a result of wear of a retaining member in a punch. 
     Still yet another object of an embodiment of the present invention is provide a rivet retention system for a rivet gun, where the effectiveness of the system does not substantially diminish as a result of glue contacting the rivet gun. 
     Briefly, and in accordance with at least one of the foregoing objects, an embodiment of the present invention provides a magnetic rivet retention system for a rivet gun, wherein a magnet is provided in a frame that is engageable with a powered handle. The magnet attracts a rivet and aligns the rivet relative to a punch and die of the rivet gun. 
     In a specific embodiment, the magnet is a rare earth magnet which is disposed in an internal chamber in a front bushing. The front bushing is threadably engaged with a back bushing, and both are disposed in a chamber which is provided in a C-frame body portion. A compression spring is also disposed in the chamber, generally between the body portion and a handle, such as a hydraulically-powered handle. As such, the rivet gun is hydraulically powered (viz-a-viz the handle) and is spring return (viz-a-viz the spring). The C-frame includes spacing for receiving a workpiece. Proximate the spacing is an opening which is in communication with the chamber in which the front and back bushings are disposed. The back end of a punch extends into the opening in the C-frame and is secured in the bore in the end of the front bushing. Preferably, a set screw secures and holds the punch in place relative to the front bushing. Proximate the spacing in the C-frame is another opening for receiving an end of a die. Preferably, a set screw is provided to secure the end of the die and hold the die in place relative to the C-frame. 
     The magnet which is disposed in the front bushing is configured to attract a rivet and assist in the alignment of the rivet relative to the punch and the die, before actuation of the rivet gun. To further assist with alignment of the rivet, a retaining member, such as a urethane ring, may be disposed on an end of the punch. In use, a rivet is placed in the retaining member, and the magnet inside the front bushing attracts and aligns the rivet. Thereafter, a workpiece is positioned in the spacing provided in the C-frame, and the rivet gun is actuated, causing the punch to move toward the die, causing the rivet to set in the workpiece. After the rivet sets, the punch returns to its starting position via a spring force (provided by the spring that is disposed in chamber in the C-frame). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The organization and manner of the structure and operation of the invention, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings, wherein like reference numerals identify like elements in which: 
         FIG. 1  is an exploded perspective view of an existing C-frame assembly for a rivet gun; 
         FIG. 2  is a side view of a rivet gun which includes a magnetic rivet retention system which is in accordance with an embodiment of the present invention; 
         FIG. 3  is an end view of the rivet gun shown in  FIG. 2 ; 
         FIG. 4  is a side view of a C-frame portion of the rivet gun shown in  FIGS. 2 and 3 ; and 
         FIG. 5  is a cross-sectional view of the internal components of a C-frame assembly of the rivet gun shown in  FIGS. 2 and 3 . 
     
    
    
     DESCRIPTION 
     While the present invention may be susceptible to embodiment in different forms, there is shown in the drawings, and herein will be described in detail, an embodiment thereof with the understanding that the present description is to be considered an exemplification of the principles of the invention and is not intended to limit the invention to that as illustrated and described herein. 
     An embodiment of the present invention provides a magnetic rivet retention system for a rivet gun, wherein a magnet is provided in a frame that is engageable with a powered handle. The magnet attracts a rivet and works to properly align the rivet relative to the rivet gun. 
     An embodiment of the present invention generally includes all of the components shown in  FIG. 1 , but does not include the threaded screw  16  and includes an internal magnet, which is not provided in the assembly shown in  FIG. 1 . 
     Specifically,  FIGS. 2-4  illustrate a rivet gun  100  which includes a C-frame assembly  102  that has a magnetic rivet retention system that is in accordance with an embodiment of the present invention. Like the C-frame assembly  10  shown in  FIG. 1 , the C-frame assembly  102  shown in  FIGS. 2-4  (see specifically  FIGS. 2 and 4 ) includes set screws  104  for securing a C-frame body  106  to a powered handle  108 , such as a hydraulically-powered handle. 
     As shown in  FIGS. 2 and 4 , the C-frame  106  includes spacing  110  for receiving a workpiece (not shown). Proximate the spacing  110  is an opening  112  (like as is shown in  FIG. 1 ) which is in communication with an internal chamber  114  in the C-frame  106  (see  FIG. 5 ). A front bushing  116  and a back bushing  118  are disposed in the chamber  114  in the C-frame  106 . Specifically, the front bushing  116  includes an internally threaded end  120  which receives a corresponding externally threaded end  122  which is provided on the back bushing  118 . Preferably, the back bushing  118  is threaded into the front bushing  116  such that a shoulder  124  on the back bushing  118  abuts an end  126  of the front bushing  116 . An opposite end  128  of the back bushing  118  provides a recess  129 , such as a hex-shaped recess for engagement with a corresponding hex tool (not shown) for threading the back bushing  118  onto the front bushing  116 . The back bushing  118  may be formed of stainless steel, for example. A compression spring  130  is also disposed in the chamber  114 , generally between the C-frame body portion  106  and the handle  108 . As such, the rivet gun  100  is hydraulically-powered, but is spring return. 
     An opposite end  132  of the front bushing  116  includes an opening  134  for receiving an end  136  of a punch  138 , such as a steel punch, which extends into the opening  112  in the C-frame  106 . A set screw  140  is disposed in a threaded bore  142  in the front bushing  116  proximate the opening  134  in the end  132  of the front bushing  116 , and engages the end  136  of the punch  138  such that the punch  138  is secured relative to the front bushing  116 . As shown in  FIG. 2 , proximate the spacing  110  in the C-frame  106  is another opening  144  for receiving a stem portion end  146  of a die  148 . Preferably, a set screw  150  is provided in a threaded bore  152  in the C-frame  106 , to secure the stem portion end  146  of the die  148  and hold the die  148  in place relative to the C-frame  106 . As shown in  FIG. 4 , the die  148  includes a recess  153  for facilitating installation of the rivet into the workpiece during actuation of the rivet gun  100 . 
     As shown in  FIG. 5 , the front bushing  116  is generally cylindrical, and disposed between the internally threaded end  120  of the front bushing  116  and the opening  134  in the front bushing  116  for receiving the end  136  of the punch  138  is an internal chamber  154 . A magnet  156 , such a cylindrically-shaped rare earth magnet, is disposed in the chamber  154 . Preferably, the magnet  156  is installed in the front bushing  116  from the rear  126  of the bushing  116 , wherein the magnet  156  is installed in the end  126  of the front bushing  116  before the back bushing  118  is threaded into the front bushing  116 . The magnet  156  may be, for example, a half inch in diameter and three-quarters of an inch long. Regardless, the magnet  156  is configured to attract a rivet  158  relative to a face surface  160  of the punch  138 , and assist in the alignment of the rivet  158  relative to the punch  138  (and the die  148  which is generally aligned with the face surface  160  of the punch  138 , across the spacing  110  of the C-frame  106 ), before actuation of the rivet gun  100 . To further assist with alignment of the rivet  158 , a retaining member  162 , such as a urethane ring, may be disposed on the punch  138 , such that the face surface  160  of the punch  138  is disposed in an opening  164  in the retaining member  162 . 
     Preferably, the magnet  156  is housed in the chamber  154  provided in the front bushing  116  such that no load is applied to the magnet  156  during operation of the rivet gun  100 . Preferably, all forces are transmitted via the back bushing  118  to the front busing  116  via a force (represented by arrow  170  in  FIG. 5 ) applied to the back bushing  118  by the hydraulics of the handle  108  of the rivet gun  100  and via the threaded engagement between the two bushings  116 ,  118  in the C-frame  106 . While the magnet  156  may either be free-floating in the chamber  154  in the front bushing  116  or may be somehow retained relative to the front bushing  116 , preferably the magnet  156  is generally isolated from the application of load. 
     In use, a rivet  158  is placed in the retaining member  162  (if so provided), and the magnet  156  inside the front bushing  116  attracts and aligns the rivet  158  relative to the face surface  160  of the punch  138 . Thereafter, a workpiece is positioned in the spacing  110  provided in the C-frame  106 , and the rivet gun  100  is actuated, causing the punch  138  to move toward the die  148 , causing the rivet  158  to set in the workpiece. After the rivet  158  sets, the punch  138  returns to its starting position via spring force applied by the spring  130  that is disposed in chamber  114  in the C-frame  106 . 
     The present invention provides an improved rivet retention system for a rivet gun in the form of a magnetic retention system. While a retaining member may be provided on the punch of the rivet gun, the effectiveness of the magnetic rivet retaining system does not substantially diminish as a result of wear of the retaining member, such as wear of its inside diameter. Additionally, the effectiveness of the magnetic rivet retaining system does not substantially diminish as a result of, for example, glue contacting the rivet gun, which may be a common occurrence in certain applications. 
     While an embodiment of the present invention is shown and described, it is envisioned that those skilled in the art may devise various modifications of the present invention without departing from the spirit and scope of the disclosure.