Patent Publication Number: US-2011070049-A1

Title: Fastener

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a fastener for joining two metal plate members and more particularly, to such a fastener, which enables the barrel to be temporarily secured to the inside of the cap by means of friction engagement, facilitating installation. 
     2. Description of the Related Art 
     When fastening plate members together, a positioning screw formed of a knob, a ring and a screw nail is usually used. During installation, the screw nail and the ring are secured to the first plate member, and then the knob is rotated to drive the screw nail into the second plate member, and then a hand tool is used to fasten tight the screw nail, affixing the first and second plate members together. This plate member joining method can be used in a machine tool to join plate members together. 
     There is known a fastener comprised of a cap, a screw member, a spring member and a barrel for joining two metal plate members together. The spring member is sleeved onto the screw, and then the barrel is attached to the cap. During installation, the barrel is affixed to a mounting through hole on a first metal plate member, and then the screw member is driven into a screw hole on a second metal plate member to join the two metal plate members together. Further, after unfastened the screw member from the screw hole of the second metal plate member and removal of the first metal plate member from the second metal plate member, the fastener is kept secured to the first metal plate member. 
       FIG. 8  is a schematic sectional side view, showing an installation status of a fastener according to the prior art design. As illustrated, the fastener comprises a cap A, a screw member B mounted in the cap A, a barrel D slidably coupled to the cap A and surrounding the screw member B, and a spring member C sleeved onto the screw member B and stopped between a part inside the cap A and a part inside the barrel D. During installation, pick up the cap A of the fastener manually, and then insert the barrel D into a mounting through hole E 1  on one metal plate member E, and then solder the bonding flange D 1  of the barrel D to the top wall of the metal plate member E around the mounting through hole E 1  with a solder paste E 2 . Thus, the fastener is secured to the metal plate member E. However, this manual installation procedure wastes much labor and time, resulting in low work efficiency. To improve work efficiency, an automatic machine may be used and operated to pick up the cap A of the fastener and to insert the barrel D into the mounting through hole E 1  of the metal plate member E. Further, in order to avoid vibration of the barrel D relative to the cap A and the screw member B during installation, a Teflon ring F may be squeezed into the barrel D and forced into friction engagement with the screw member B. After the barrel D is locked to the screw member B by the Teflon ring F, the barrel D can be bonded to the top wall of the metal plate member E around the mounting through hole E 1  with the solder paste E 2  accurately. After bonding of the barrel D to the metal plate member E, the cap A is operated to rotate the screw member B and to force the Teflon ring F away from the barrel D. Using the Teflon ring F to temporarily lock the barrel D to the screw member B complicates the installation procedure. Further, when squeezing the Teflon ring F into the barrel D, the Teflon ring F may be deformed and the barrel D may be biased relative to the screw member B, affecting installation accuracy. 
     Therefore, it is desirable to provide a fastener for joining metal plate members that eliminates the aforesaid problems. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished under the circumstances in view. It is therefore an object of the present invention to provide a fastener for joining metal plate members, which facilitates installation and presents the spring member from falling out of the barrel during installation. It is another object of the present invention to provide a fastener for joining metal plate members, which facilitates quick installation by an automatic installation machine without any secondary installation procedure, saving much installation time and labor. 
     To achieve these and other objects of the present invention, a fastener comprises a barrel for fastening to a mounting through hole of a first metal plate member, a screw member inserted through the barrel for threading into a screw hole of a second metal plate member to joint the first and second metal plate members together, a cap molded from plastics or rubber on the screw member for holding the barrel temporarily on the inside by means of friction engagement between the barrel and the cap, a spring member sleeved onto the screw member and stopped between the shoulder of the screw member and an inside annular flange of the barrel, and a C-shaped retainer ring fastened to the shank of the screw member to prohibit falling of the screw member out of the barrel. By means of friction engagement between the cap and the barrel, the barrel is temporarily secured to the inside of the cap, enabling the barrel to be quickly installed in the mounting through hole of the first metal plate member by an automatic machine by means of a reflow soldering process. After bonding of the barrel to the first metal plate member, the cap can be rotated to release the barrel, for enabling the screw member to be driven into the corresponding screw hole on the second metal plate member to affix the first metal plate member and the second metal plate member together. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an elevational view of a fastener in accordance with the present invention. 
         FIG. 2  is an exploded view of the fastener in accordance with the present invention. 
         FIG. 3  is an exploded view, partially in sectional elevation, of the fastener in accordance with the present invention. 
         FIG. 4  is a sectional side view of the present invention, showing the cap, the screw member, the spring member ad the barrel assembled before mounting of the C-shaped retainer ring. 
         FIG. 5  is a sectional side view of the present invention, showing the fastener assembled. 
         FIG. 6  is a schematic sectional view of the present invention, showing the barrel of the fastener bonded to a metal plate member before attachment of the first metal plate member to a second metal plate member. 
         FIG. 7  corresponds to  FIG. 6 , showing the first metal plate member attached to the second metal plate member and the screw member threaded into the corresponding screw hole of the second metal plate member. 
         FIG. 8  is a schematic sectional side view, showing an installation status of a fastener according to the prior art design. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 1-3 , a fastener in accordance with the present invention is shown comprising a barrel  1 , a screw member  2 , a cap  3 , a spring member  4  and a C-shaped retainer ring  5 . 
     The barrel  1  is a metal member having a tubular body  11 , an inside accommodation space  10  defined in and cut through top and bottom sides of the tubular body  11  for accommodating the screw member  2  and the spring member  4 , an inside annular flange  111  protruded from the inside wall of the tubular body  11  and suspending in the inside accommodation space  10 , a bottom extension tube  12  axially forwardly extended from the bottom side of the tubular body  11 , a friction flange  13  extending around the periphery of the tubular body  11  adjacent to the bottom extension tube  12 , and a bonding face  121  defined between the bottom extension tube  12  and the friction flange  13 . 
     The screw member  2  is a metal member having a head  21 , an engagement portion  211  formed on the periphery of the head  21 , a plain shank  22  perpendicularly extended from the center of the bottom wall of the head  21 , a threaded shank  23  axially extended from one end of the plain shank  22  opposite to the head  21  and carrying a thread  231  around the periphery, a shoulder  221  connected between the bottom wall of the head  21  and the plain shank  22 , and a tool groove  24  located on the top wall of the head  21 . Further, the tool groove  24  can be a Phillipes groove, keystone groove, asterisk groove or hex groove. 
     The cap  3  is a hollow member having a center opening  30  axially extending through the top and bottom sides for receiving the barrel  1 , the screw member  2  and the spring member  4 , friction means  32 , for example, friction ribs  321  protruded from the inside wall within the center opening  30  and extended to the front open side  31  of the center opening  30  for friction with the friction flange  13 , an inside retaining groove  33  extending around the inside wall within the center opening  30  near the top side for retaining the engagement portion  211  of the screw member  2 , and a grip  34  located on the periphery at the top side for gripping by hand. 
     The spring member  4  is sleeved onto the plain shank  22  and threaded shank  23  of the screw member  2  and stopped the between inside annular flange  111  of the barrel  1  and the shoulder  221  of the screw member  2 . 
     The C-shaped retainer ring  5  is mounted in the inside accommodation space  10  of the barrel  1  and retained to the plain shank  22  and stopped between the inside annular flange  111  of the barrel  1  and the thread  231  of the threaded shank  23  of the screw member  2  to prohibit the screw member  2  from falling out of the barrel  1 . 
     Further, the screw member  2  is a metal member. The cap  3  can be molded from a plastic or rubber material on the head  21  of the screw member  2  by over molding. Alternatively, the cap  3  can be fastened to the head  21  of the screw member  2  by means of any of a variety of joints or by a bonding technique to have the engagement portion  211  of the screw member  2  be fixedly secured to the inside retaining groove  33  of the cap  3 . Thus, by means of manipulate the grip  34 , the user can rotate the screw member  2  with less effort. Further, the engagement portion  211  can be formed of barbs, teeth or conical protrusions. 
     Referring to  FIGS. 4 and 5  and  FIGS. 2 and 3  again, after molding of the cap  3  on the head  21  of the screw member  2  or fixation of the cap  3  to the head  21  of the screw member  2 , the spring member  4  is sleeved onto the plain shank  22  and threaded shank  23  of the screw member  2  and stopped with its one end against the shoulder  221  of the screw member  2 , and then the barrel  1  is inserted into the center opening  30  of the cap  3  to stop the inside annular flange  111  against the other end of the spring member  4  and to force the friction flange  13  into friction engagement with the friction ribs  321  in the center opening  30  of the cap  3 . Thus, the barrel  1  is temporarily secured to the cap  3 . At this time, the threaded shank  23  of the screw member  2  suspends outside the barrel  1 . Thereafter, a crimping tool or the like (not shown) is used to attach the C-shaped retainer ring  5  to the screw member  2 , forcing the C-shaped retainer ring  5  along a tapered inside surface portion  101  into a positioning groove  102  in the inside accommodation space  10  of the barrel  1  so that the C-shaped retainer ring  5  is stopped at the inside annular flange  111  of the barrel  1  and retained to the thread  231  of the threaded shank  23  of the screw member  2  to prohibit the screw member  2  from falling out of the barrel  1 . 
     Further, when pressing the cap  3  onto the barrel  1 , the friction ribs  321  of the friction means  32  of the plastic or rubber cap  3  will be forced into friction engagement with the coarsened surface  131  of the friction flange  13  to hold the barrel  1  in the cap  3  temporarily. The coarsened surface  131  can be an embossed surface having densely distributed raised portions or protrusions. Further, a number of barrels  1  can be joined by a material strip during their fabrication. This fabrication method facilitates product pickup, simplifies the manufacturing process, increases the yield rate and lowers the manufacturing cost. Further, a linked series of barrels can easily and rapidly be installed in one first metal plate member, and the follow-up installation of the respective caps is also easy. 
     Referring to  FIG. 6 , during installation, an automatic pickup machine is used to catch the cap  3  of the fastener and to move the fastener in axial alignment with one mounting through hole  61  on a first metal plate member  6 , and then to insert the bottom extension tube  12  of the barrel  1  of the fastener into the mounting through hole  61  of the first metal plate member  6  and to have the bonding face  121  of the barrel  1  be attached to the solder paste  52  been applied to the border area of the mounting through hole  61  of the first metal plate member  6 , and then a reflow soldering process is applied to have the barrel  1  be bonded to the first metal plate  6 . 
     Referring to  FIG. 7  and  FIGS. 2 ,  3  and  6  again, after installation of the barrel  1  in the first metal plate member  6 , rotate the grip  34  of the cap  3  to move the friction means  32  of the plastic or rubber cap  3  away from the coarsened surface  131  of the friction flange  13  to hold the barrel  1  for enabling the spring member  4  to push the barrel  1  out of the cap  3 . At this time, the screw member  2  is moved axially with the cap  3  relative to the barrel  1  and received inside the barrel  1 . By means of the positioning of the C-shaped retainer ring  5  on the periphery of the plain shank  22  of the screw member  2  between the inside annular flange  111  of the barrel  1  and the thread  231  of the threaded shank  23  of the screw member  2 , the screw member  2  is prohibited from falling out of the barrel  1 . The first metal plate member  6  can then be attached to a second metal plate member  7  to keep the mounting through hole  61  of the first metal plate member  6  in alignment with a corresponding screw hole  71  on the second metal plate member  7 . Thereafter, force the cap  3  downwards and rotate the cap  3  to drive the outer thread  231  of the screw member  2  into the screw hole  71  of the second metal plate member  7 , and then attach a hand tool (for example, screwdriver) to the tool groove  24  of the screw member  2  and rotate the hand tool to tighten up the connection between the screw member  2  and the second metal plate member  7 . Thus, the first metal plate member  6  and the second metal plate member  7  are firmly secured together by the fastener. 
     It is to be understood that For example, the barrel  1  can be made of aluminum, brass, zinc alloy or any other metal material; the coarsened surface  131  of the friction flange  13  around the periphery of the tubular body  11  of the barrel  1  can be formed by means of an extrusion, embossing or milling technique; the cap  3  can be molded from a plastic or rubber material; instead of the design of friction ribs  321 , the friction means  32  of the cap  3  can be an embossed surface or a number of teeth or conical protrusions for friction engagement with the coarsened surface  131  of the barrel  1  to temporarily secure the barrel  1  to the inside of the cap  3  and to facilitate installation of the barrel  1  of the fastener in the mounting through hole  61  of the first metal plate member  6  by an automatic machine by means of a reflow soldering process. After installation of the barrel  1  of the fastener in the mounting through hole  61  of the first metal plate member  6 , the operator can rotate the grip  34  of the cap  3  to disengage the friction means  32  of the cap  3  from the coarsened surface  131  of the barrel  1  for enabling the first metal plate member  6  to be attached to the second metal plate member  7  and locked thereto by the fastener. Thus, the invention eliminates a secondary installation procedure to mount the cap on the barrel after bonding of the barrel to the first metal plate member as employed according to the prior art design. Therefore, the invention greatly saves much installation labor and installation time. 
     A prototype of fastener for fastening metal plate members has been constructed with the features of  FIGS. 1-7 . The fastener functions smoothly to provide all of the features disclosed earlier. 
     Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.