Abstract:
Repeated inserting, tightening, loosening, and removing of external threads to internal threads can increase the likelihood of cross threading and thread damage. A spring loaded gear bolt assembly, which promotes alignment of mating threads before applying torque, is described. A spring is disposed on the back end of a bolt shaft to promote alignment of lead mating threads before twisting to engage external to internal threads. A gear chain translates a single hand rotation to thread two bolts into respective affixed internal threaded holes, simultaneously. A spring loaded gear bolt assembly and method described herein promote increased thread life and ease of use ease for test plate securing. Efficient single handed manipulation of multiple bolts simultaneously can be achieved using a test plate assembly, which included spring loaded gear bolt assemblies, as described herein. Applications of a spring loaded gear bolt include infrared adapter test plate assemblies.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to preventing thread damage across pairs of external bolt threads and internal mating threads. Thread damage is an ongoing challenge in bolt fastening applications. Numerous factors can contribute to thread damage. Repeated fastening and unfastening may add to the opportunity for damaging threads. Cross threading can lead to fastener failure. Different bolt applications and configurations can present additional challenges for potential cross threading as compared with a conventional straight on bolt and nut application. 
     It would be desirable to provide a method and system which promoted alignment of external bolt threads and internal mating threads to preserve external and internal threads. 
     SUMMARY OF THE INVENTION 
     The present invention addresses the issue of thread preservation in securing or fastening applications across external bolt threads and internal affixed. The present invention provides a spring loaded gear bolt assembly which protects lead threads and affords aligning the male and female threads before engaging mating threads. A test plate assembly comprising spring loaded gear bolt assemblies, in accordance with the present invention, permits simultaneous alignment of multiple sets of bolt threads and affixed internal threads with a single-handed operation. Certain aspects of the present invention are briefly described below but are not exhaustive. Further, any one embodiment in accordance with the present invention may include any of the certain aspects described below. 
     One aspect of the present invention is that it may be incorporated into a test plate assembly. 
     Another aspect of the present invention is that affords alignment of lead threads before application of torque upon the threads. 
     Another aspect of the present invention is that it promotes on axis contact of lead threads despite an off axis application of insertion force; and further, another aspect of the present invention is that it facilitates axial thread alignment despite the application of torque at an off axis point and the application of torque upon a bolt shaft at less than the bolt circumference. 
     Another aspect of the present invention is its ready incorporation into a single handed test plate mounting assembly. 
     Another aspect of the present invention is that the aligning force can be varied as needed for the application requirements. 
     Another aspect of the present invention is that the displacement afforded by the aligning force can be varied. 
     Another aspect of the present invention is that the aligning force and displacement can be varied independently. 
     Another aspect of the present invention is the binding-free mounting of a test plate assembly to an affixed assembly, which is afforded in part by spring loading, in accordance with an embodiment of the present invention. 
     Yet another aspect of the present invention is the relative hardness of parts in the gear bolt assembly, to preserve the gear bolt assembly as well as the lead threads on the bolt and in the mounting plate. 
     An aspect of the present invention is a decreased potential for cross threading; embodiments enable seating of the bolt evenly before turning to translate male threads of bolt shaft into female threads of affixed receptor, which decreases the chances of cross threading. 
     Another aspect of the present invention is the protection of threads during insertion and securing of multiple bolts simultaneously with a single hand. 
     Those skilled in the art will further appreciate the above-noted features and advantages of the invention together with other important aspects thereof upon reading the detailed description that follows in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       For more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures, wherein: 
         FIGS. 1A-1D  show a top view, side view, front isometric view, and a back view, respectively, of an embodiment of a test plate assembly utilizing a gear bolt assembly, in accordance with an embodiment of the present invention; sent invention 
         FIG. 2  shows an exploded view of a test plate assembly which employs a gear bolt assembly, in accordance with an embodiment of the present invention; 
         FIGS. 3A-3B  shows a perspective view of the gear plane and an exploded view of the same, respectively, in accordance with the present invention; 
         FIG. 4  shows a drawing of an exemplary gear bolt assembly in accordance with an embodiment of the present invention; 
         FIG. 5  shows a cross section of a solid rendering of a test plate assembly, along line X-X  FIG. 1A ; 
         FIGS. 6A-6B  shows a block diagram of a method of securing a test plate assembly to an affixed receiving plate and a method of aligning at least two sets of lead external bolt shaft threads and affixed internal mating threads mounted in a receiving plate, respectively; and 
         FIG. 7  shows a front view of an exemplary receiving plate, to which an embodiment of a test plate assembly in accordance with the present invention, may be attached. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention, as defined by the claims, may be better understood by reference to the following detailed description. The description is meant to be read with reference to the figures contained herein. This detailed description relates to examples of the claimed subject matter for illustrative purposes, and is in no way meant to limit the scope of the invention. The specific aspects and embodiments discussed herein are merely illustrative of ways to make and use the invention, and do not limit the scope of the invention. Element Reference numbers in the figures are consistent across figures, when possible. Parts are not necessarily identical across figures and are not necessarily consistent across embodiments. 
       FIGS. 1A-1D  show a top view, side view, front isometric view, and a back view, respectively, of an embodiment of a test plate assembly utilizing a gear bolt assembly in accordance with an embodiment of the present invention.  FIG. 1A  shows a top view of a face plate of a test plate assembly, in accordance with an embodiment of the present invention. Centered in the face plate  110  is grip  120 . A user will rotate grip  120  clockwise  121  to secure the test plate assembly  100 , shown in  FIG. 1B  to the mounted receiving plate. And conversely, rotating grip  120  counter-clockwise  122  will loosen the test plate assembly  100  for removal. In  FIG. 1A , dust cap  130  is shown secured to the adapter, not shown, while a dust cap holder  132  is within tether  133  distance for ready storage during testing. 
       FIG. 1B  shows a side view of a closed test plate assembly  100  in accordance with an embodiment of the present invention. Adapter  125  provides electrical connections for the desired voltage tests. Spring housings  140 ,  145  extend outward from the face plate  110  on which they are mounted. As shown in  FIG. 1A , spring housings  140 ,  145  are at the lower left and upper right corners of the face plate  110 . For example, the depth of the adapter  125 , grip  120  and spring housings  140 ,  145  may not be shown to scale. And these elements, for example, can vary in diameter and depth as desired in accordance with an exemplary embodiment of the present invention. Similarly, the height of the dust cap holder can vary and may be threaded. 
       FIG. 1A  shows the spring housing secured to the face plate  10  via a pair of screws  18 . Additional screws  18  secure the face plate  10  to the back plate  90 , where back plate  90  is shown in side view  FIG. 1B . 
     In diagonal corners opposite the spring housings  45 ,  40  are aligning pin holes  12 ,  17 , which extend through both the face plate  10  and the back plate  90 , as shown in  FIGS. 1A and 1C . The aligning pins, not shown, are affixed to the receiving plate. The receiving plate, not shown, houses the pins or other connection types to be tested. 
       FIG. 1C  shows a front isometric view of spring housings  40 ,  45  adapter  25 , and grip  20 , and their relative positions on face plate  10 .  FIG. 1C  also provides a perspective view of aligning pin holes  17 ,  12  on a first diagonal and the spring housings  40 ,  45  on a second diagonal. Bolt shafts  80 ,  85  extend out the back side  91  of back plate  90 . Turning to  FIG. 1D , contact pin pads  38  extend through openings  98  in the back plate  90 . Bolt shafts  85 ,  80  extend through the back plate as well. 
       FIG. 2  shows an exploded perspective view of the test plate assembly  100 . The inside  92  of the back plate  90  faces the back of circuit board  60 . The gear chain  350  rests atop circuit board  60 , which is disposed between the face plate  10  and the back plate  90 .  FIGS. 3A-3B  show the gear chain and its relation to the gear housing  70 ,  76  in greater detail. Bolt shafts  80 ,  85  extend through back plate  90  before entering respective gear housings  70 ,  76 . Inserted in gear housings  70 ,  76  are respective springs  80 S,  85 S. The gear housing and bolt shaft are shown in greater detail in  FIG. 4 . Gear housings  70 ,  76  extend from the gear chain  350  through face plate  10 . Spring housings  40 ,  45  cover the portion of the respective gear housing, which extends out of the face plate  210 , and in which respective springs  80 S,  85 S are housed. The user grip  20  is mounted on the face plate  10  and is used by a user to secure and remove the test plate assembly,  100  from the receiving plate, not shown. Also shown extending from the front of the face plate is adapter  25 , which is capped by dust cap  30 . 
     In accordance with an exemplary embodiment of the present invention in ensemble of o-rings is used throughout the test plate assembly to withstand salt water and other corrosive environments. O-ring  48  frames circuit board  60  and is disposed between face plate  10  and back plate  90 . 
       FIG. 3A  shows a perspective view of the gear chain  350 , which is housed between face plate  10  and the back plate  90 , and just above the circuit board  60 . Circuit board  60  is disposed inside a large recess  97  of the inside  92  of back plate  90 . Gear housings  70 ,  76  are shown extending out of inner sides  92  back plate  90 , whilst bolt shafts  80 ,  85  extend out the opposite side  91  of the back plate  90 . Stem  355  engages, is connected to, center gear  354 , which connects the grip (not shown) to the gear chain  350 . In accordance with an exemplary embodiment, an over torque clutch is disposed between the grip and gear housing, to prevent over torque on the threads of the bolt shaft. 
       FIG. 3B  is an exploded view of the gear chain  350  and circuit board  60  in the back plate  90 . End gears  358 ,  353  engage the respective gears  75 ,  78  on the gear housings  70 ,  76 . Gears in the gear chain rest between spacers  373 , separating the gear from the circuit board surface  60 . The gear chain  350  rests in the recess  97  of the back plate  90 . The gear  75 ,  78  of respective gear housing  70 ,  76  are also set into a recess  97  of back plate  90 , and rest on a respective spacer, not shown. The number of gears in the gear chain  350  and relative ratios may vary across embodiments, as desired or as space and load requirements dictate. 
       FIG. 4  shows a detailed view of a gear bolt assembly  400 , in accordance with an exemplary embodiment of the present invention. Bolt shaft  480  has a thread-less insertion lead  460  with an outer diameter that is just less than the minor diameter of the internal threads in the receiving plate. The diameter of the thread-less insertion section  460  is also less than the minor diameter of the threaded bolt section  456 . The thread-less insert section backs up to the threaded portion  456  of the bolt shaft  450 . In accordance with the exemplary embodiment of  FIG. 4 , the total threaded length is 0.20 inches. In alternate embodiments the thread length can be longer or shorter as desired or as needed to withstand the resultant load. According to one exemplary embodiment, the bolt shaft is under tensile load when bolted into the receiving plate. In alternate embodiments, the parameters, such as, pitch, major axis, minor axis, thread height, and thread length of the bolt shaft can vary as desired or as needed to meet application requirements. The material of the bolt shaft or threads can also vary. 
     A thread-less section  455  follows the threads  456 . The thread-less section  455  has an outer diameter less than the minor diameter of the threads  456 . Next to the thread-less section  455  is a displacement limiting shoulder section  454 . Referring to  FIG. 2 , back plate  290  has through-holes in diagonal corners through which bolt shafts  280 ,  285  pass, where an exemplary bolt shaft is shown as  450  in  FIG. 4 . The upper end, or head end,  452  of bolt shaft  450  inserts into gear housing  470 . Bolt shaft  450  inserts into gear housing  470 , which has a spring end  471  and a gear and  475 . Gear housing  470  has an inner diameter which affords ready insertion of the bolt shaft  450 . 
     Bolt shaft  450  has a through hole  452  which is aligned with through slot  473  in the gear housing. Dowel  472  passes through the top slot  473  and hole  452  and out the bottom slot, not shown, of the gear housing. The distance of hole  452  to the head  451  of the bolt shaft is less than the distance of the slot to the  471  end of the gear housing  470 . After insertion of the bolt shaft into the gear housing and after insertion of dowel  472  through the slot  473  and whole  452 , there is empty headspace in gear housing  470 . Spring  480  inserts, at least partially, into gear housing  470 . The outer diameter of spring  480  fits easily into the diameter of the gear housing and rests against the head of the bolt  451 . 
       FIG. 5  shows a cross section of a gear bolt assembly as disposed in a test plate assembly, in accordance with an embodiment of the present invention, along line X-X of  FIG. 1A . When the gear bolt assembly is mounted in a test plate assembly  500 , spring housing  540  fits over the head end of gear housing  570  and any spring portion  580  which extends past the housing  570 . Dowel  572  has an outer diameter which affords ready displacement along the gear housing axis riding in the slot  573 . In accordance with one exemplary embodiment the slot  573  permits 1/10 of an inch displacement of the bolt shaft relative to the gear housing. A method of securing a test plate assembly  500  to receiving plate and a method of assembling a spring-loaded gear bolt assembly are described in reference to  FIG. 5 . 
     In accordance with the present invention, an exemplary embodiment of a spring loaded gear bolt assembly comprises: a spring  580   580   s ; a spring housing  540 ; a gear housing  570  with slot  573  and gear  575 ; a bolt shaft  550  with a through hole  553 , a shoulder  554 , a threaded section  556 , and an insert section  560 ; and a dowel  572 . Bolt shaft  550  inserts through opening in the back plate  590  and into gear housing  570 . Gear  575  of gear housing  570  rests in a recess  597  of back plate  590  while the head-end of gear housing  570  extends through face plate  510 . Disposed in the head end of the gear housing  570  and resting on the head end of bolt shaft  550  is spring  580   580   s . Atop spring  580  and surrounding the portion of the gear housing, which extends past the face plate  510 , is spring housing  540 . 
     In accordance with an exemplary embodiment, insertion section  560  has radiused edges  561  and an outer diameter  562 , which is less than the minor diameter of internal receiving threads affixed in a receiving plate. An exemplary receiving plate is shown in FIG,  7 . A receiving plate, to which a test plate assembly in accordance with an embodiment of the present invention may be secured, may be an infrared adapter receiving plate. The infrared adapter receiving plate may be affixed on an aircraft, manned or unmanned, for which flare deployment is desired. Further, while embodiments of the present invention are described, for example in  FIGS. 1-5 , in relation to an infrared adapter, or infrared decoy flare receiving plate, a test plate assembly and spring loaded gear bolt assembly in accordance with the present invention can be modified and employed to other types of receiving plates. For example, a chaff, or electronic counter measure, receiving plate can be affixed to any aircraft and a test plate assembly housing a spring loaded gear bolt assembly, in accordance with an exemplary embodiment of the present invention, may be secured thereto for testing purposes. The placement of the spring loaded gear bolt assembly within the test plate assembly can be varied to align with affixed internal receiving threads, and the dimensions, e.g. frontal plane dimensions, of the test plate assembly can be varied as needed or desired to mount to a specific receiving plate. 
       FIG. 7  does not show electrical contact pins of the receiving plate, which may align with some or all of contact pads  38 , shown in  FIG. 1D . The number and placement of contact pads  38  in a test plate assembly, in accordance with the present invention, may also vary as desired or needed to correspond with electrical contacts in a receiving plate.  FIG. 7  shows affixed internal threads  785   a,    780   a  into which the bolts  80 ,  85  ( FIG. 1 ) will thread. In opposite corners, corresponding to the exemplary embodiment of  FIGS. 1A-1D , pins  712   a  and  717   a  correspond to through holes  17  and  12  ( FIGS. 1A and 1D ). 
     After placing the gear housing  570  into recess  597  and after placing additional intermediate parts, such as the gear chain  565  and the circuit board, not shown, the face plate  510  and back plate  590  can be secured together. The bolt shaft  550  can be inserted through opening  596  and secured in the gear housing by aligning the hole  553  of bolt shaft  550  with the slot  573  of the gear housing  570  and inserting the dowel  572 , as shown in  FIG. 5 . In accordance with the embodiment of  FIG. 5 , gear  575  rests on a washer  578  at its gear end  575  and up against spring housing  540  on its other end, fixing, at least in part, the position of the gear housing in the Z direction  505 . With a spring  580   s  placed into the head end of the gear housing  570 , the spring housing  540  can enclose the spring  580   s  and the exposed end of the gear housing  570  and can be secured to face plate  510 . 
     Once the test plate assembly  500  is assembled it can be secured to the receiving plate. In accordance with one exemplary embodiment, the receiving plate is a flare loading plate, which is affixed to, for example, an aircraft. In accordance with the present invention, single handed mounting, securing, and removing are enabled. Referring to  FIG. 1B , grip  120  can be used to align the holes  112  and  117  to the receiving plate pins  712   a,    717   a  ( FIG. 7 ). Additionally, a notch  113  may be present and aligned on a receiving bar or channel lock. The inserting end  560  of bolt shaft,  FIG. 5 , will align with corresponding internal threaded holes in the receiving plate. Centering the single handed grip  130 ,  FIG. 1A , on the face plate  110  ergonomically favors balance across the test plate assembly  100  in both frontal plane directions x and y. According to one exemplary embodiment, the spring constant of spring  580  ( FIG. 5 ) is one pound. When the insertion end of the bolt shaft  560  ( FIG. 5 ) acquires an impacting force of one pound or greater, the bolt shaft  550  will displace along its axis as afforded by slot  573  and space  595 . This axial displacement will enable the lead external threads  556  to align with corresponding lead internal threads on the receiving plate. By compressing the spring and evenly seating the mating threads before rotating the grip, the likelihood of cross threading is reduced. Even with repeated securing and removal of the test plate assembly  500  to a receiving plate, threads  556  are preserved and protected. Further, this protection is provided to two spatially separated bolts simultaneously during the simultaneous securing of said two bolts from a single site of torque application, which is a user grip. Single handed securing and removing of a test plate assembly into a receiving plate is afforded by the present invention, while enabling alignment of threads before engaging and loading external and internal threads of two respective bolts. 
     In yet other embodiments, additional gear bolt assemblies can be employed. Possible configurations include a gear chain running across the opposite diagonal, referring to  FIG. 3A . In another embodiment, the circuit board  60  ( FIG. 2 ) can be displaced from the gear chain. For example a gear chain plate could be disposed on the face plate side of circuit board. 
     Referring to  FIG. 1D , contact pads  38 , which are distributed across the face of the back plate, will depress corresponding pin contacts of the receiving plate when the test plate assembly is secured to the receiving plate. In accordance with one exemplary embodiment, thirty pounds of pressure are applied via the contact pads to depress the army of contact pins on the receiving plate. The desired electrical connection is provided from the receiving plate pins to adapter  25  ( FIG. 1B ) for testing. In alternate embodiments, the form of electrical connections between the receiving plate and the test plate assembly can vary as desired or as needed in accordance with the configuration of the receiving plate. 
     As described above, the present invention affords simultaneous alignment and subsequent securing of two bolts using a single handed operation. Additional gear bolt assemblies can be employed at additional places along the gear chain. The gear chain can be expanded or shortened in length. Similarly a gear chain running in the opposite direction, or another direction can be employed. Displacing the circuit board from the gear chain would afford multiple center gear, gear chain, to gear housing configurations. A single gear, e.g. a large gear at center gear  354  position, may replace the gear chain  350  to provide connection to gear end of gear housings  78 ,  75  ( FIGS. 3A and 3B ), placed about the circumference of the single gear. Additional gear housings can be positioned along the circumference of the single gear as needed for load accommodation or receiving plate configuration. 
     In accordance with an exemplary embodiment, for example as shown in  FIGS. 1A-1D , aligning pins on the receiving plate  717   a,    712   a  are provided to assist in aligning the connection of the test plate assembly with the receiving plate. The translation afforded by space  95  and slot  73  ( FIG. 5 ) may lessen binding of the test plate assembly on the pins during insertion. The binding-free, or reduced binding, mounting of a test plate assembly to an affixed receiving plate assembly is afforded in part by spring loading, in accordance with an embodiment of the present invention. The binding reduction can be adjusted by respective spring constants and by the number of springs employed, where a spring  80 S is comprised in a gear bolt assembly, shown for example in  FIGS. 5 and 4 . 
     Another aspect of the present invention is that the aligning force can be varied as needed for the application requirements. The aligning force can be adjusted by the choice of spring used in the gear bolt assembly. Another aspect of the present invention is that the displacement afforded by the aligning force can be varied. The displacement obtained in response to the applied aligning force can be adjusted by, for example, by the length of slot  73  and the depth of recess  95 . In turn, in accordance with embodiments of the present invention, the aligning force and displacement can be varied independently. 
       FIG. 6A  shows a block diagram of a method of securing a test plate assembly to an affixed receiving plate. Through holes in a test plate assembly are aligned with pins in a receiving plate  610 . The test plate assembly is pushed towards the receiving plate  620 . The lead end of at least one bolt is inserted into a corresponding internally threaded hole in the receiving plate  630 . Using a user grip, the user pushes on a face plate of the test plate assembly, which compresses a spring within the spring loaded gear bolt assembly and mates the corresponding lead threads  640 . Once the spring loaded gear bolt assembly compresses, the user may turn the user grip which will apply a torque on the bolt shaft, threading the external bolt threads into the internal threads  650 . 
       FIG. 6B  shows a block diagram of a method of simultaneously aligning at least two sets of lead external bolt shaft threads and affixed internal mating threads mounted in a receiving plate. A user first obtains spring loaded gear bolt assemblies  615  and a test plate assembly which housed at least two spring loaded gear bolt assemblies  625 . The user positions the test plate assembly juxtaposition the receiving plate with internal mating threads  635 . Contact is made between lead external threads and corresponding internal threads in the receiving plate  645 . Pressing on the front plate of the test plate assembly, compresses a spring in respective spring loaded gear bolt assemblies, displacing the at least two bolt shafts normal to the receiving plate aligning mating threads axially  655 . Then, turning a user grip on the front plate of the test plate assembly will apply a torque on the bolt shaft, threading the external threads into the mated internal threads of the receiving plate. 
     The present invention enables inserting and threading of two bolt shafts simultaneously with one hand, while aligning respective lead threads before torque application, which decreases the potential for cross threading, wherein the bolt threads are machine threads not designed to cut. While specific alternatives to steps or elements of the invention have been described herein, additional alternatives not specifically disclosed but known in the art are intended to fall within the scope of the invention. Thus, it is understood that other applications of the present invention will be apparent to those skilled in the art upon reading the described embodiment and after consideration of the appended claims and drawings.