Abstract:
An improved fastener installation tool is provided that is used to install a threaded nut onto a threaded fastener bolt where access to the bolt head is not possible. The fastener bolt has a threaded shank with a noncircular recess that is adapted to receive a complimentary shaped hex key or hold bit installed in a socket gear of a power driven tool which is used to install a threaded nut onto the threaded shank of the fastener bolt. A spring biased retainer slide with an extended rod portion hold the hex key securely in a locked position. Manual retraction of the retainer slide allows the extended rod portion to release the hex key so it may be replaced when damaged without any need for any further disassembly or need for additional disassembly tools.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
       [0002]    Not applicable. 
       REFERENCE TO SEQUENCE LISTING 
       [0003]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    The invention relates generally to improvements in power tools used in the installation of threaded fasteners and more particularly, to a quick-change socket and key retainer assembly for specialized threaded fasteners of the type used in aerospace and related industries. 
         [0006]    2. Brief Statement of the Prior Art 
         [0007]    A variety of specialized fasteners have been developed and are widely used in the aerospace and related industries. These specialized fasteners have been designed to meet specific design criteria for a variety of applications. One such fastener is currently in widespread use throughout the aerospace industry. The Hi-Lok® type fastener was developed by Hi-Shear Corporation and is manufactured under a variety of names. The Hi-Lok® type fastener is particularly adapted for fastening two or more metal panels or workpieces together where there is no access to the bolt head. That is, the fastener is designed to fit through a preformed opening in a substrate or workpiece with the bolt head inaccessible by the power tool used in the installation of the fastener. 
         [0008]    The Hi-Lok® type frangible fastener includes two basic components, a bolt component which has a bolt or head end and a threaded end, and a collar component which has an internally threaded body portion and a torque limiting drive nut portion. Generally, a series of appropriately spaced holes are bored in the workpiece. One of the most important features of this fastener is that it enables the fasteners to be installed with the installation tooling disposed on one side of the workpiece assembly. 
         [0009]    The bolt component is inserted from the opposite side of the panel assembly, that is, the side inaccessible to the power tooling. The body of the collar component of the fastener is then threaded a few turns onto the exposed threaded end of the bolt component from the accessible side of the workpiece assembly. 
         [0010]    The power tooling that drives the fastener includes a rotary socket member which has a forwardly opening noncircular, preferably hex recess that engages the torque limiting drive nut portion of the collar component. In addition to the hex socket, the power tooling has a centrally located rotationally stationary noncircular, preferably hex key or hold bit which is adapted to snugly fit into a broached hex cavity located in the threaded end portion of the bolt component of the fastener. The rotary socket member is rotated by a powered motor in the power tool body, and threadedly drives the collar component of the threaded fastener down onto the bolt component until a predetermined torque preload on the workpiece assembly is reached. At the same time that the collar component is threaded onto the threaded bolt component the rotationally stationary noncircular or hex key or hold bit mounted to the broached hex cavity in the threaded shank of the bolt component holds the fastener against rotation. Upon reaching the predetermined torque limit, the drive nut portion of the collar component is automatically sheared from the threaded body of the collar component which then becomes the nut portion of the fastener. This unique feature avoids over-torquing the fastener as well as eliminates the need for manually monitoring the torque on the fastener. 
         [0011]    A problem that continues to exist with this type of fastener installation tool is the tendency of the hex key or hold bit to twist or otherwise deform. Additionally, changing the hex key or hold bit after damage or after wear or to a different size key is a relatively slow procedure due to the various mechanisms proposed to prevent the hex key or hold bit from rotating relative to the fastener during installation of the nut. 
         [0012]    The prior art proposes various power tools for the installation of Hi-Lok® type frangible fasteners. Zils, U.S. Pat. No. 4,462,281, discloses a straight drive type of tool wherein the socket and hex key approach the workpieces at right angles relative to the general plane of the workpieces. The Zils tool has the disadvantage that if the key is damaged or broken, disassembly of portions of the head assembly of the tool is required in order to remove and replace the hex key. It also has the disadvantage that the key may be difficult to remove because of sealant fouling, and a twisted hex key may not even be removable for replacement, or may damage the key holder, requiring almost complete disassembly of the tool head for removing the stuck key and its key holder. These disadvantages translate into substantial manual effort and tool downtime. 
         [0013]    Bochman, U.S. Pat. No. 3,027,789, discloses a geared L-head-type tool that might be applicable to a Hi-Lok® type frangible fastener, although there is no mention of a frangible fastener in this patent. Replacement of the key would require disassembly of a sub-housing which houses an enlarged key head and key spring from the main tool head. This would require substantial manual effort and tool downtime. 
         [0014]    Bosten, U.S. Pat. No. 3,584,527, discloses a power tool which, by its nature, could be applied to a Hi-Lok® type frangible fastener, although its stationary key has a Phillips screwdriver-type head. It is a straight, offset drive which would require substantial disassembly, and hence manual effort and tool downtime, to remove and replace the bit or key. 
         [0015]    Bangerter et al., U.S. Pat. No. 3,323,394, discloses a straight drive power tool which is generally similar to the tools disclosed in both Bosten and Zils, but has a torque-limiting clutch associated with the bolt-restraining bar. As with both the Bosten and Zils devices, the Bangerter al. device would require substantial disassembly to remove and replace a broken bar or key, requiring substantial effort and downtime. The binding problem discussed in connection with Zils would also be equally applicable to Bosten and Bangerter et al. 
         [0016]    Batten, U.S. Pat. Nos. 4,538,483 and 4,617,844, disclose what purports to be a ball detent type quick-release and replacement system for removal of a damaged or broken drive head of the tool. There are a number of drawbacks with the ball-detent type of retention systems. The key has to be manually pulled out of the front end of the holder which requires a separate gripping tool such as pliers. For removal and replacement of the hex key, the ball detent system requires that the key holder be pulled rearwardly against the force of the retention spring, and then a “flipper” or spacer block be pivoted under the head of the holder to bring the detent in the holder into axial registry with the internal annual groove in the socket member. The retention springs are sometimes so rigid as to require a special tool to pry them up in order to get the flippers underneath them. 
         [0017]    Another problem with the ball detent retention system is that contamination entering the interface region between the hex key and the holder key way often prevents extraction of the key from the key holder. 
         [0018]    Gauthreaux et al., U.S. Pat. No. 7,874,232, discloses a quick connect socket and hex key retainer assembly wherein a lever is slid in one direction to lock the retaining slide into locked position. When the retaining slide is moved into the locked position, the retaining slide slides into and engages an annular groove that is located around the circumference of the exterior surface of the drive shaft of the socket of the socket assembly. Once the retainer slide is engaged with the annular groove, the socket assembly is secured and engaged to the gear head of the fastening tool with a lock screw. In order to change a hex key the complete socket assembly must be removed and disassembled from the power tool. 
         [0019]    There exists, therefore a need for further improvements in and to fastener installation tools of the type having a hex key or hold bit coaxially disposed within a power drive socket for engaging a hex cavity located in the threaded end portion of the bolt component of a Hi-Lok® style fastener, particularly with respect to providing a simplified quick connect or disconnect feature for replacing the hex key or hold bit member. 
       SUMMARY OF THE INVENTION 
       [0020]    In accordance with the invention, an improved fastener installation tool is provided of the type having a hex key or hold bit retainer assembly for engagement with a mating recess in the shank end of a threaded fastener while an accompanying power driven socket drives a threaded nut onto the threaded fastener shank using any convenient pneumatic or power driven tool. The fastener installation tool consists of a tool component and a drive head. Generally the fastener installation tool includes a torque overload clutch within the tool component to permit the hex key or hold bit retainer rotation in response to a torque load exceeding a predetermined limit thereby preventing hex key or hold bit retainer breakage. The improved fastener installation tool is adapted for quick and easy disengagement of the hex key or hold bit retainer thereby allowing quick and easy hex key removal and replacement. 
         [0021]    The preferred embodiment of the quick disconnect installation tool consists of a tool head having an elongated hex key or hold bit coaxially mounted within a rotatably driven socket associated with a power driven device for power driven socket rotation. The hex key or hold bit is held rotatably fixed but longitudinally movable relative to the power drive socket for retraction therein as the power drive socket advances a threaded nut on the threaded shank of the bolt. The hex key or hold bit retainer tip has a noncircular cross-section (preferably a hexagonal cross-section) for seating into a mating recess formed in the threaded shank end of the bolt so as to support and hold the bolt against rotation during installation of the threaded nut onto the threaded shank of the bolt. 
         [0022]    The fastener installation tool has a tool head, a gear drive consisting of a series of gears ending with a socket gear. The socket gear has at one end a gear configuration on its exterior surface which is adapted to mesh with one of the series of gears of the gear drive. A hex key or hold bit arrangement is coaxially disposed with the socket gear which houses a rotationally stationary hex key or hold bit which is longitudinally moveable relative to the socket gear against the action of a biasing spring. The gear drive and socket gear are disposed within the tool head. The gear configuration on the exterior surface of the drive socket matingly engages one of the series of gears disposed within the tool head. The hex key or hold bit has a shank with a noncircular exterior surface (preferably a hexagonal cross-section) and a tip with a noncircular external surface (preferably a hexagonal cross-section). The shank of the hex key or hold bit is disposed coaxially with the drive socket. The tip of the hex key or hold bit has a tip end that matingly engages a complementary shaped noncircular recess in the shank of the fastener or bolt. 
         [0023]    It is therefore a primary object of the present invention to provide a novel Hi-Lok® installation tooling system having a true quick-release and replacement retention system for the hex key or hold bit yet is greatly simplified relative to prior art retention systems. 
         [0024]    Another object of the present invention is to provide a hex key retention system which enables simple manual removal of only the hex key for replacement and requires no additional tools or further disassembly of other components of the tool head. 
         [0025]    A further object of the present invention is to provide a Hi-Lok® installation tooling system wherein hex key ejection and replacement from the key holder is by simple manual manipulation of an externally exposed spring biased slide retainer instead of requiring that the key holder be removed from the socket component which holds the hex key with a set screw and roll pin. 
         [0026]    A still further object of the present invention is to provide a Hi-Lok® type frangible fastener installation tooling system which is a substantial improvement over conventional Hi-Lok® installation tool systems currently in use. 
         [0027]    These and other features and advantages of the present invention will become apparent from the following more detailed description taken in conjunction with the accompanying drawings which illustrate by way of example, the principals of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  is an isometric view of the fastener installation tool engaged with the gear drive head and retainer slide housing in accordance with the present invention; 
           [0029]      FIG. 2  is a partial cross-sectional view of the gear housing of the gear drive of the fastener installation tool in accordance with the present invention; 
           [0030]      FIG. 3  is a partial cross-sectional view of the socket assembly and associated hex key or hold bit in accordance with the present invention disclosed herein; 
           [0031]      FIG. 4A  is an isometric view of the retaining slide housing in accordance with the present invention; 
           [0032]      FIG. 4B  is a bottom view of the retainer slide mounted in the retainer slide housing holding the hex key or hold bit to prevent it from turning in accordance with the present invention; 
           [0033]      FIG. 4C  is a cross-sectional view of  FIG. 4B  along arrows  4 - 4  in accordance with the present invention; and 
           [0034]      FIG. 5  is a partial cross-sectional view of the gear housing of the gear head of the fastener installation tool and an exploded view of the socket and hex key or hold bit in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0035]    Specialized threaded fasteners are often utilized in applications where there is no access to the bolt head. In such applications, it is well known that Hi-Lok® type fasteners are adapted to fasten two or more metal panels or workpieces together where there is no access to the bolt head. Hi-Lok® type fasteners require the use of a fastener installation tool having a hex key or hold bit which is inserted into a complementary broached recess in the shank end of a bolt type fastener to hold the fastener stationary while a noncircular (usually hex head) threaded nut is threaded onto the threaded shank of the bolt fastener by use of a power driven socket that is attached to a power driven installation tool. When the threaded nut is completely threaded onto the shank end of a bolt with the fastener installation tool and the bolt is restrained against rotation by the hex key or hold bit, the fastener is properly secured. In many such fastener installation tools, it is very difficult and time consuming to remove and replace the hex key or hold bit from the socket of the fastener tool when a hex key or hold bit breaks or is damaged and requires replacement. Such problem also exists when it is necessary to replace the hex key or hold bit when the size of the socket is changed to a larger size and the broached recess of a large size bolt type fastener increases in size. Therefore, an object of the present invention is to provide a fastener installation system that provides a quick disconnect arrangement for the hex key or hold bit which can be exercised with minimum disruption of the gear head or socket assembly and is accomplished quickly without using any hand tools. 
         [0036]      FIG. 1  is an isometric view of a fastener installation tool  10  engaged to a tool attachment assembly  12 . The fastener installation tool  10  shown has a tool component  14  and the tool attachment assembly  12  has a gear head  16 . The tool component  14  is shown as having a power lever  18  and a pneumatic port  20 . During the use of the pneumatic port  20  is connected to at least one pneumatic hose (not shown), which in turn is connected to at least one pneumatic pressure source (now shown). Alternatively, the fastener installation tool  10  may be powered by various other types of drive devices including, but not limited to, hydraulic energy, direct current (DC), or alternating current (AC) electricity, battery power or any other power energy provider. In the illustrated device the power lever  18  must be depressed in order for the fastener installation tool  10  to be powered on. In other power driving devices, various other types of switches, buttons, or levers may be employed instead of the power lever  18  shown in  FIG. 1 . 
         [0037]    With reference to  FIGS. 1-2 , the fastener installation tool  10  gear head component  16  has a gear box  22  including upper  24  and lower  26  cover plates, a socket assembly  28 , a retainer slide housing  56 , a retainer slide  52  and biasing spring  32  and a hex key or holder bit  34  and associated release spring  36  which will be described in detail hereinafter. 
         [0038]    With reference to  FIGS. 1-5 , the gear head  16  includes a gear box  22  having an upper cover plate  24  and a lower cover plate  26  defining the gear box  22  in a conventional manner. The gear head  16  is adapted to provide a quick-connect coupling to the drive end of the tool component  14  such as a rotary drive tool of the type well known in the art. Upon actuation of the tool component  14 , the tool component  14  supplies rotary drive motion through a gear train  38  mounted in the gear box  22  of the gear head  16  to the socket gear  40 . The socket  42  has a noncircular (i.e. hexagonal) seat  44  for receiving and rotatably driving the threaded nut  46 . The hex key or hold bit  34  is mounted in a slip fit arrangement in a tubular bore  47  generally co-axially within the socket gear  40 . One end  48  of the hex key or hold bit  34  is adapted to fit through the threaded nut (not shown) so as to avoid interference with installation of the threaded nut onto the threaded shank of the bolt fastener. The hex key or hold bit  34  is moved longitudinally within the tubular threaded bore of the threaded nut in a sliding displacement and constrained against rotation relative to the bolt fastener by the mating engagement of an extended rod portion  50  of a retainer slide  52  that resides in a slotted aperture  66  in the outer diameter of the hex key or hold bit  34  as will be hereinafter set forth in detail. The retainer slide  52  is mounted for sliding movement within a complementary cavity  54  in the bottom surface of a retainer slide housing  56  which itself is securely mounted to the top surface of the upper cover plate  24  of the gear housing  22 . The retainer slide housing  56  also includes an upright boss  58  at one end thereof which includes a (noncircular/typically hexagonal) through passage  60  for receiving the end portion of the hex key or hold bit  34  in sliding engagement. The upright boss  58  further has a bore  62  larger than the through passage  60  for housing a spring  36  that exerts a force against the end of the hold bit or hex key  34  and is adapted to bias the hex key or hold bit  34  in a downward direction. A threaded cap  37  holds the spring  36  in the bore  62  of the upright boss  58 . The spring  36  exerts sufficient downward force on the hex key or hold bit  34  to maintain the tip  68  of the hex key or hold bit  34  into continuous contact with the complimentary recess in the threaded shank of the fastener bolt while the threaded nut  46  is installed on the threaded shank of the fastener bolt. The hex key or hold bit  34  is secured in the through passage  60  of the upright boss  58  by the extended rod portion  50  of the retainer slide  52  by the force of a spring  32  biasing the retainer slide  52  in a direction towards the upright boss  58  and thereby moving and maintaining the extended rod portion  50  of the retainer slide  52  into a longitudinal slotted aperture  66  cut into the outside periphery of the hex key or hold bit  34 . 
         [0039]    The hex key or hold bit  34  is released from its position coaxial with the socket gear  40  by pulling back on a release trigger knob  72  mounted to the slide retainer  52  wherein when the slide retainer  52  is moved in a direction away from the upright boss  58  and the extended rod portion  50  of the retainer slide  52  moves out of the slotted aperture  66  in the outer periphery of the hex key or hold bit  34 . The hex key or hold bit  34  is ejected from the socket gear  40  by the biasing force of the spring  36  housed in the bore  62  of the upright boss  58 . This is easily accomplished by simply exerting a force on the release trigger knob  72  in a direction away from the upright boss  58 . 
         [0040]    An indexing head  74  is also mounted to the top surface of the upper cover plate  24 . The indexing head  74  contains an indexing mechanism so that tool component  14  may be indexed relative to the gear head  16  to enable easy alignment of the hex key tip  68  with the broached hex key recess in the threaded shaft of the bolt fastener. An index sleeve  76  having an internal gear form thereon is mounted to an index body  80  having an external gear  81  meshing with the internal gear  77  of the index sleeve  76  which in turn is securely bolted to the upper cover plate  24  of the gear box housing  22 . The index sleeve  76  also has an external threaded end  78  for receiving an internally threaded collar  82 . The internally threaded collar  82  provides the interface between the power tool component  14  and the gear head  16 . A drive adapter  84  is connected at one end to the power tool component  14  and an opposite end to a mating drive gear within the gear train  38 . 
         [0041]    In operation, the socket  42  of the socket gear  40  on the gear head  16  carries the threaded nut of appropriate size for power driven threaded engagement with the threaded shank of the fastener bolt. The hex key or hold bit  34  tip  68  is initially seated and engaged with the complimentary recess in the fastener bolt shank. When the power lever  18  is depressed to initiate driving of the socket gear  40 , the threaded nut  46  and socket  42  are advanced along the threaded shaft of the bolt fastener towards the workpiece thereby moving in a downward direction relative to the hex key or hold bit  34  which remains seated and engaged within the complementary recess in the end of the threaded shank of the fastener bolt. During such relative movement of the socket  42 , the hex key or hold bit  34  experiences relative upward movement displacement as a result of the socket&#39;s  42  downward displaced position, upon completion of the power drive threaded nut installation onto the fastener bolt. Such upward displacement of the hex key or hold bit  34  bears against the release spring  36  through a washer  39  and thereby causes the release spring  36  to compress. Throughout this movement, the release spring  36  maintains a downward bias force on the hex key or hold bit  34  to maintain the hex key or hold bit  34  tip  68  in engagement with the complimentary recess in the fasteners bolt shank. Also during this relative movement the slotted aperture  66  in the periphery of the hex key or hold bit  34  permits the extended rod portion  50  of the retainer slide  52  to slide along the bottom of the slotted aperture  66  to keep the hex key or hold bit  34  securely locked to prevent rotation thereof. Upon completion of the threaded nut installation, the gear head  16  and associated socket  42  and hex key or hold bit  34  are manually retracted from the fastener bolt and installed nut and may then be employed for installation of another nut onto another fastener bolt. 
         [0042]    If any time during this operational procedure the power tool operator wishes to replace the hex key or hold bit  34 , the fastener installation tool  10  is simply manually retracted from the fastener bold which results in the hex key or hold bit  34  being removed from the complimentary recess in the threaded shank of the fastener bolt. The operator further manipulates the release trigger knob  72  by overcoming the bias of spring  32  and sliding the retainer slide  52  in a direction away from the upright boss  58  which results in the extended rod portion  50  of the retainer slide  52  retracting from the slotted aperture  66  on the outer periphery of the hex key or hold bit  34  in turn allowing the hex key or hold bit  34  by the biasing force of the release spring  36  to be removed from the socket gear  40  and replaced with a new hex key or hold bit  34 . 
         [0043]    Although the invention has been described with reference to the preferred embodiment, it should be understood by those skilled in the art that the scope of the invention is not limited to that embodiment. Rather, changes to the details of the embodiment may be made without departing from the spirit and scope of the invention as claimed. 
         [0044]    What is claimed is: