Patent Publication Number: US-6990722-B2

Title: Method and apparatus for connecting a fastener element to a wall

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This disclosure relates to a method and apparatus for connecting an internally threaded fastener element to a wall by cold expanding a non-threaded tubular portion of the fastener element within an opening in the wall and providing the fastener element with wall contacting flanges on both sides of the wall. 
   2. Description of the Related Art 
   The aerospace industry utilizes a fastener that is in the nature of a tubular rivet with internal threads. The fastener can be installed in seconds into an opening in a wall from one side of the wall. No finishing work is required once the fastener is installed. It is ready for use With clean threads available for screw attachment. This tubular rivet has a flange on one end. The opposite end is inserted into the opening in the access side of the wall and the tubular rivet is pushed into the opening until the flange is against the access of the wall. A rod with a threaded end is then inserted into the tubular rivet from the access side of the wall and is connected to threads inside the tubular rivet. Then, a hand or power tool is operated to pull on the rod. This causes a reduced wall portion of the tubular rivet on the blind side of the wall to radially bulge and form a second flange that tightly engages the blind side of the wall. A tubular rivet system of this type is currently provided by RIVNUT.RTM. Engineered Products, Inc. of Kendallville, Ind. An early form of this type of system is disclosed by U.S. Pat. No. 2,384,347, granted Sep. 4, 1945, to Michael Schultz. A problem with known tubular rivets is that they often rotate in the opening when torque is applied to a screw that is connected to the tubular rivet after it has been installed. 
   It is known to install a nut holder on a wall at the location of an opening in the wall and then connect a nut to the installed nut holder. A tubular stem portion of the nut holder is inserted into the opening in the wall and is then radially expanded to connect it to the wall and also cold work the wall material surrounding the opening for fatigue life enhancement. Then the nut is connected to the nut holder to provide bolt receiving threads. Examples of this type of system are disclosed by U.S. Pat. No. 5,096,349, granted Mar. 17, 1992, to Michael A. Landy, Roger T. Bolstad, Charles M. Copple, Darryle Quincey, Eric T. Esterbrook, Leonard F. Reid and Louis A. Champoux, and by U.S. Pat. No. 5,468,104, granted Nov. 21, 1995, to Leonard F. Reid and Charles M. Copple. The radial expansion locks the nut holder against rotating but these systems require attachment of a nut to provide the wall insert with the internal threads. 
   There is a need for a method and apparatus for installing a fastener element with internal threads in an opening in a wall in such a way that the tubular rivet is restrained against rotating in response to a bolt being threaded into the fastener element. An object of the present invention is to provide such a method and apparatus. 
   BRIEF SUMMARY OF THE INVENTION 
   In one aspect, a method of contemporaneously connecting and torsionally securing a fastener to a work piece with a tool that controls the cooperation between a rod and a mandrel wherein the rod is axially fixed with respect to the tool and free to rotate relative to the tool, the mandrel is concentrically located around and axially displaceable relative to the rod, and the mandrel has a tapered segment formed by a reduced perimeter connected with a cold working perimeter; engaging a first portion of the rod with a complementary portion of the fastener; inserting the fastener into an opening in the work piece, the complementary portion of the fastener being positioned on a blind side of the work piece and an opposing end of the fastener being positioned on an access side of the work piece; moving the tapered segment of the mandrel into contact with the opposing end of the fastener, a region of the reduced perimeter of the tapered segment at least partially positioned within an opening in the fastener while the cold working perimeter remains located slightly outside of the opening in the fastener; seating the mandrel against the opposing end of the fastener; axially drawing the rod from the blind side toward the access side of the work piece in an amount sufficient to cause buckling in a region of the fastener, the buckled region of the fastener forming a flange on the blind side of the work piece; and driving the cold working perimeter of the mandrel through the opening in at least the portion of the fastener residing between the blind side and the access side of the work piece to radially expand at least a portion of the fastener residing between the blind side and the access side of the work piece. 
   These and other advantages, objects, and features will become apparent from the following best mode description, the accompanying drawings, and the claims, which are all incorporated herein as part of the disclosure. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Like reference numerals are used to designate like parts throughout the several views of the drawing, wherein: 
       FIG. 1  is an exploded pictorial view showing the front end portion of a puller tool in a spaced relationship to a fastener element, and showing a threaded rod on the tool that is adapted for engaging the fastener element; 
       FIG. 2  is a view like  FIG. 1 , but showing the threaded rod entering the fastener element; 
       FIG. 3  is a view like  FIGS. 1 and 2 , but showing the threaded rod inside the fastener element; 
       FIG. 4  is a fragmentary view showing the front end components of the puller tool in side elevation and a wall and the fastener element in longitudinal section; 
       FIG. 5  is a view like  FIG. 4 , but showing a mandrel on the tool that is positioned to where it is ready to move into the fastener element; 
       FIG. 6  is a view like  FIGS. 3 and 5 , but showing a relative retraction of the threaded rod for collapsing a wall portion of the fastener element so as to form a second wall engaging flange that completes a connection of the fastener element to the wall; 
       FIG. 7  is a view like  FIGS. 4–6 , but showing the mandrel base moved into contact with the wall and showing the mandrel moved into the portion of the fastener element that is in the opening in the wall; 
       FIG. 8  is a side elevational view of an example puller tool, with some parts shown in section; 
       FIG. 9  is an enlarged scale longitudinal sectional view of a part of the puller tool, with some parts shown in side elevation, such view showing a fluid motor schematically; 
       FIG. 10  is a view like  FIG. 9 , but omitting some more of the rear portion of the puller tool, such view showing the mandrel base and the mandrel extended from the position shown in  FIG. 9 ; 
       FIG. 11  is a view like  FIG. 10 , but showing a sleeve that surrounds the mandrel base extended from the position shown in  FIGS. 9 and 10 ; 
       FIG. 12  is an enlarged scale view of the front end portion of the puller tool showing the mandrel and the mandrel base in longitudinal section; 
       FIG. 13  is a fragmentary view showing the mandrel and portions of the mandrel base and showing the threaded rod in side elevation, such view showing the mandrel in the same position that is shown in  FIG. 6 ; and 
       FIG. 14  is a view like  FIG. 12 , but showing the mandrel in the same position that is shown in  FIG. 7 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIGS. 1–14 , a puller tool  10  is shown to comprise an elongated tubular housing  12  having an annular front wall  14 . Wall  14  includes a center opening  16  through which a tubular sleeve  18  extends. A tubular mandrel base  20  is received within a center opening  22  in sleeve  18 . A tubular mandrel  24  projects axially outwardly from a radial end surface  26  on mandrel base  20 . As best shown in  FIG. 12 , a rod  28  extends through a center opening  30  in the mandrel base  20  and the mandrel  24 . As will hereinafter be described in greater detail, the inner end of the rod  28  is connected to a rotor  31  within housing  12 . The outer or free end of the rod  28  includes a threaded portion  32  that is adapted to mate with threads that are inside of a fastener element  34 . 
   Referring to  FIGS. 4 and 5 , the fastener element  34  has first and second opposite end portions  36 ,  38 . End portion  36  is tubular and includes a flange  40  at its outer end. The illustrated flange  40  is adapted to fit into a tapered countersink  48  that is formed in a wall W on the first side  42  of the wall W. The countersink  48  is formed at the end of a wall opening  44  on the first side of the wall W. The tubular first end portion of the fastener element  34  includes an annular sidewall region  46  of reduced thickness. When the fastener element  34  is positioned within the wall opening  44 , and the flange  40  is within the countersink  48  ( FIGS. 13 and 14 ), the reduced thickness region  46  is positioned on the second side of the wall W closely adjacent wall surface  50 . 
   Fastener element  34  includes an internally threaded socket  52 , the threads of which mate with the threads on the threaded end portion  32  of the rod  28  ( FIGS. 4–7 ). As shown by  FIG. 5 , the mandrel  24  is movable relatively along the rod  28  until its outer end  54  is in contact with the outer end of opening  56  in the tubular first end portion  36  of the fastener element  34 .  FIG. 13  shows that the outer end portion  54  is radiused. The outer diameter of mandrel  24  is larger than the inner diameter  58  of center opening  56  ( FIG. 13 ). The end portion  54  of mandrel  24  has an outer end that is slightly smaller in diameter than opening  36 . As a result, when the mandrel  24  is moved relatively towards the wall W, the end portion  54  of mandrel  24  is partially within the opening  56 . 
   Referring to  FIGS. 5 and 6 , when mandrel surface  54  is at the outer end of the opening  56 , and the rod  28  is pulled relatively into the mandrel  24  and the mandrel base  20 , the threaded end portion  32  on rod  28  is moved towards the mandrel  24 . A force is exerted on the fastener element  34  that collapses the annular sidewall region of reduced thickness  46 , causing it to form a radial second flange  60 . The relative pull on the rod  28  and the consequent pull on the internally threaded portion  52  of the fastener element  34  causes the flange  60  to move tight against the wall surface  50  and at the same time pull the flange  40  tight against the countersink surface  48 . In a different embodiment, the flange  40  may be a radial flange having a radial inner surface that is against the surface  42  of wall W. In such embodiment, the flange  60  is still moved tight against the wall surface  50 . Thus, in either embodiment, the portion of the wall W that immediately surrounds the first end portion  36  of the fastener element  34  is trapped axially between the conical flange  48 , or a radial flange used in its place, and the flange  60 . 
   In a further embodiment, the flange  40  may be omitted so that the end of the end portion  36  of fastener element  34  is flush or over flush when end portion  36  is within the opening  44 . The threaded rod will hold the fastener element  34  in place, while the mandrel tapered end surface  54  extends to contact the tubular end portion  36  of the fastener element  34  and react the pull on the threaded rod  28 . The rod  28  is pulled into the puller  10 , causing the thin wall portion  60  to collapse against the back of the work piece W. While still holding the fastener  34  in place by use of the rod  28 , the mandrel  24  is pushed into the opening  56 , causing the fastener end portion  36  to be expanded into the work piece opening  44 . Resistance to torque and push out are achieved by the high interference fit of the expanded fastener in the work piece opening  44 . Elimination of the taper flange eliminates one of the fabrication steps, via the countersinking of the work piece opening  44  to receive the flange  40 . Elimination of the taper flange eliminates one of the fabrication steps, via the countersinking of the work piece opening  44  to receive the flange  40 . 
   Referring to  FIGS. 8–14 , at its end opposite the rod  28 , the rotor  31  is connected to a shaft  62  that in turn is connected at its end opposite the rotor  31  to a rotary output of a rotary motor  64 , shown schematically in  FIG. 9  in the form of a fluid motor.  FIG. 9  shows a fluid inlet  66  and a fluid outlet  68 . The fluid can be compressed air that is discharged to the atmosphere. Or, it can be hydraulic fluid that is returned from the motor  64  to either a reservoir or the inlet of a pump (not shown) that pumps fluid to the motor  64 . Rotor  31  is supported within housing  12  by a suitable antifriction bearing  70 . The rod  28  is rotatable relative to the mandrel base  20  and the mandrel  24  but the threaded end  32  is axially fixed in position. 
   Referring to  FIGS. 8–11 , the front end portion includes radial front wall  14 , a radial rear wall  74 , and a radial intermediate wall  76 . There is a sealed connection between the cylindrical wall  12  of the puller tool  10  and the walls  14 ,  74 ,  76 . Tubular sleeve  18  extends through an opening  16  in wall  14 . At its rear end, sleeve  18  includes a piston  80 . Piston  80  makes a sealed sliding contact with wall  12 . Sleeve  18  makes a sealed sliding contact with wall  14 . A first working chamber  82  ( FIGS. 9 and 10 ) is formed forwardly of piston  80 , between piston  80  and wall  14 . Chamber  82  is radially between wall  12  and sleeve  18 . A chamber  84  is formed on the opposite side of piston  80 , axially between piston  80  and wall  76 . 
   The mandrel base  20  is positioned forwardly of a sleeve  86  that extends rearwardly from mandrel base  20  to a rear end portion  88  that extends through an opening  90  in wall  74 . A second piston  92  projects radially outwardly from sleeve  88 , at a location axially between walls  74 ,  76 . Sleeve  86  then projects forwardly from piston  92 , through an opening  94  in wall  76 , onto the mandrel base  20  to which its front end is attached. A suitable seal is provided between sleeve  88  and opening  94  and between the outer periphery of the piston  92  and wall  12 . A working chamber  96  is defined axially between wall  74  and piston  92  and radially between sleeve  88  and wall  12 . On the opposite side of piston  92 , a second working chamber  98  is formed axially between wall  76  and piston  92 , and radially between sleeve  86  and wall  12 . 
   The rotary motor  64  is rotated for the purpose of threading the threaded end portion  32  of rod  28  into or out from the threads  52  in the fastener element  34 . Initially, the rod  28  and threaded portion  32  are rotated to connect the threaded portion  32  to a fastener element  34  ( FIGS. 1–3 ). Then, after flange  60  has been formed and the end portion  36  of fastener element  34  has been attached to the wall W, the rod  28  and the threaded end portion  32  are rotated in the opposite direction, for unthreading the threaded portion  32  from the threads  52 . In an alternate embodiment, the rotary motion of the mandrel can be accomplished manually in lieu of being driven by the rotary motor. 
   The puller tool  10  may include a pistol grip handle  100  and the necessary controls, including a trigger  102 , for rotating the motor  64  either clockwise or counterclockwise, and for introducing fluid pressure into one of the working chambers  82 ,  84  while removing fluid from the other working chambers  82 ,  84 , and for introducing working fluid into one or the other of the working chambers  96 ,  98  while removing it form the other working chamber  96 ,  98 . Or, a coiled return spring could be put into one of the chambers and fluid put into and removed from the other chamber. 
   As earlier stated, the rod  28  is rotated for the purpose of threading the threaded end portion  32  of rod  28  either into or out from the internal threads  52  is a fastener element  34 . The rod  28  only rotates; it does not move axially. However, relative axial movement is caused by movement of the pistons  80 ,  92  and the sleeves  18 ,  86 ,  88 . According to a method of the invention, after a fastener element  34  is attached to the threaded end portion  32  of the rod  28  ( FIG. 3 ), the tool  10  and fastener element  34  are moved towards the wall W, in alignment with an opening  44  in the wall W, and then the fastener element  34  is moved into and through the wall opening  44  until its flange  40  is seated on the portion of the wall W that immediately surrounds the wall opening  44 . When the flange  40  is a tapered flange, it fits within a tapered countersink  48 . If the flange is a straight radial flange, its inner surface would lie flat on a flat portion of wall  42  which would immediately surround the opening  44 .  FIG. 4  shows the rod in a relatively extended position and shows the fastener element  34  within an opening  44 . Next, fluid is introduced into working chamber  96  and is removed from working chamber  98 . This moves the sleeves  86 ,  88  and the mandrel base  20  and mandrel  24  towards the threaded end portion  32  of the rod  28 . Initially, movement occurs until the mandrel  24  is in the position shown by  FIG. 5 , with its tapered end surface  54  contacting the perimeter of opening  56  in tubular end portion  36 . Then, the sleeves  86 ,  88  and the mandrel base  20  and mandrel  24  are moved further towards the threaded end portion of rod  28 . This causes a shortening of the distance between the threaded end portion  32  and the mandrel end surface  54 . It also causes a pulling force to be exerted on the second end portion  38  of the fastener element  34 , pulling it towards the wall W. Mandrel  24  exerts a reaction force on the flanged end of fastener element  34 , keeping it within the opening  44 . The pull on end portion  38  causes the annular sidewall region of reduced thickness  46  to collapse on itself and move radially outwardly into the position shown by  FIGS. 6 ,  7 ,  13  and  14 . The collapsing wall portion  46  forms the flange  60  and is moved into tight engagement with the second side  50  of wall W. At the same time, the flange  40  is moved into tight contact with the surface  48  on the first side  42  of wall W. The portion of the wall W immediately surrounding the opening  44  is clamped tightly between the two flanges  40 ,  60 . Further movement of the threaded end portion  32  of rod  28  towards the mandrel  24 , causes the mandrel  24  to be forcibly moved into the end opening  56  in fastener element  34 . 
   As clearly shown by  FIG. 13 , the exterior diameter of mandrel  24  is initially larger than the internal diameter of opening  56 . The tapered end surface  54  cams its way into the opening  56 , causing the end portion  36  of fastener element  34  that is in the opening  44  to be expanded radially. Radial expansion of fastener portion  36  causes a radial expansion of the wall material immediately surrounding the opening  44 . The portion  36  of fastener element  34  is moved into a tight frictional engagement with the side surface of opening  44  securing the fastener element  34  against rotation relative to the wall W. Radial expansion of the wall material immediately surrounding the opening  44  may also be sufficient to cold expand the wall region for fatigue enhancement. The expansion of fitting end portion  36  is sufficient to cause a permanent increase in the inside and outside diameters of the tubular end portion  36 . This radial expansion of the tubular end portion  36  does two things. Firstly, it introduced fatigue life enhancing compressive residual stresses in the work piece W immediately surrounding the work piece opening  44 . Secondly, it creates a high interference fit between the fitting end portion  36  and the sidewall of the opening  44 . This high interference fit secures the fitting  34  to the work piece W. 
   For a more complete description of fatigue enhancement by cold expansion, reference is made to U.S. Pat. No. 3,566,662, granted Mar. 2, 1971, to Lewis A. Champoux, entitled “Coldworking Method and Apparatus”. This patent is hereby incorporated herein by this specific reference. 
   As a comparison of  FIGS. 8–13  will show, the annular outer end surface  110  on sleeve  18  may be positioned in contact with the wall W as one way of pulling the threaded end portion  32  of rod  28  relatively into the tool  10  ( FIG. 11 ). Then, the sleeve  18  can be retracted ( FIG. 9 ) in order to move the threaded end portion  32  relatively outwardly from the tool. Then, an extension of the sleeves  86 ,  88  may be used to move the mandrel  24  and the mandrel base  20  out from sleeve  18  while moving the threaded end portion  32  of rod  28  relatively close to the mandrel  24  and the mandrel base  20 . 
   After a fastener element  34  has been attached to the wall W, and the mandrel  24  has been moved into the tubular end portion  36  for the purpose of radially expanding it into the opening  44 , the piston  92  in the sleeves  86 ,  88  can be retracted for moving the mandrel  24  and the mandrel base  20  away from the threaded end portion  32  of rod  28 . After the mandrel  24  is completely withdrawn from the end opening  56  in the fastener element  34 , the motor  64  can be operated for rotating the rod  28  in a direction that unscrews its threads from the threads  52  inside of the fastener element  34 . This unthreading is continued until the threaded end portion  32  is no longer connected to the threads  52 . Then, the tool  10  can be easily moved away from the installed fastener element  32  in the hole opening  44 . 
   The outer surface of tubular end portion  36  of fitting  34  may be machined or otherwise treated in order to give it an increase coefficient of friction. For example, when the fitting is being turned on a lathe, a series of small grooves may be formed in the outer surface of end portion  36 , so as to create outwardly projecting rings between the grooves which have sharp edges and will penetrate into the sidewall of the work piece opening  44  when the end portion  36  is expanded by the mandrel  24  as described above. 
   All of the above U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet, are incorporated herein by reference, in their entirety. 
   The illustrated embodiments are only examples of the present invention and, therefore, are non-limitative. It is to be understood that many changes in the particular structure, materials and features of the invention may be made without departing from the spirit and scope of the invention. Therefore, it is my intention that my patent rights not be limited by the particular embodiments illustrated and described herein, but rather determined by the following claims, interpreted according to accepted doctrines of claim interpretation, including use of the doctrine of equivalents and reversal of parts.