Abstract:
A method and apparatus for restricting rotation of a threaded fastener, the apparatus including a bracket member having a securing segment and an extending segment that are integrally linked wherein the securing segment forms a recess and the extending segment forms at least one restraining surface wherein a bonding material that solidifies and remains flexible upon curing is provided within the recess and, with the threaded fastener received within an aperture, the bracket member is positionable such that one end of the threaded member is receivable within the recess and within the bonding material prior to curing and the restraining surface contacts a surface of a receiving member to restrict motion of the bracket member about the aperture.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to fasteners, and more specifically to a rotation restraining device for use in limiting rotation and loosening of threaded fasteners. 
     Although threaded fasteners are commonly used in industrial applications, environmental factors associated with such industrial applications can adversely affect the effectiveness of such fasteners. Industrial applications, for example, often include dynamic loading and motive devices that cause vibration and “shock” forces that affect mechanical joints formed by such fasteners. In addition, many industrial applications require motors, generators, and other industrial devices that generate excessive amounts of heat and therefore temperatures and related humidities in industrial environments are difficult to control. 
     Vibrational and shock forces, cyclical heating levels, and other environmental conditions have been known to cause threaded fasteners to rotate and loosen. While rotation of threaded fasteners has always been problematic, the loose fastener problem has become exacerbated recently as more industrial equipment is constructed from plastic. This is because plastic deforms and relaxes more readily than other rigid materials when subjected to adverse industrial application environments. 
     Complicating matters, threaded fasteners are often difficult to access inside equipment. Factory and industrial installations, for example, are often short on space, and industrial equipment, therefore, is designed to minimize size rather than to provide adequate access to fasteners. Furthermore, to save floor space, equipment is often installed in locations that are difficult to access. 
     For these reasons it would be advantageous to have a fastener assembly that would essentially lock threaded fasteners in their fastening positions. 
     BRIEF SUMMARY OF THE INVENTION 
     It has been recognized that a simple restraining device can be provided to lock threaded fasteners in their fastening positions by providing an elongated member that forms a recess at one end and a restraining surface at another where the recess is sized so as to receive one end of a fastener and the restraining surface is formed so as to abut a surface of a receiving member (i.e., the member that receives the fastener) such that the elongated member cannot rotate in the direction corresponding to the loosening direction for the fastener. A fluid adhesive is provided within the recess and around the fastener end and forms a solid that fills the space between the recess surface and the received end. 
     An exemplary embodiment of the invention includes an apparatus for use with a fastener and a receiving member, the fastener including a first end and a threaded extension that extends from the first end, the receiving member forming an aperture along an axis for threadably receiving the extension and also forming at least a first surface that is essentially parallel to the axis and that is at least in part non-concentric with the aperture. The threaded member is removable from the aperture via rotation in a first direction. The apparatus comprises a bracket member including at least a securing segment and an extending segment that are integrally linked, the securing segment forming a recess, the extending segment extending laterally from the securing segment and forming a restraining surface. The apparatus also includes a bonding material that becomes solid and flexible upon curing, the bonding material provided within the recess. 
     With the threaded member received within the aperture and un-cured bonding material within the recess, the bracket member is positionable such that the first end is receivable within the recess and the restraining surface contacts the first surface, the surfaces together restrain rotation of the bracket member in the first direction about the axis. 
     Thus, one object is to provide an apparatus for limiting or restricting rotation of a threaded fastener. A related object is to prevent fasteners from becoming loose. 
     Another object is to provide a fastener restraining device that can easily and relatively quickly be installed. To this end the recess can be relatively larger than the received fastener end as the cured adhesive fills in the remaining gap. Thus, the device can be installed without having to precisely align a fastener end with the receiving recess. 
     One other object is to provide a device that can be installed without requiring tools. As indicated above no additional tools ar eurd to install the present device. 
     Moreover, yet another object is to provide a restraining system that can be used with many different fastener types. To this end the recess can be oversized so that various fastener head sizes (i.e., small and large) and shapes (i.e., square, hexagonal, octagonal, standard of Philips screw, etc.) can be accommodated. Again, the adhesive fills in the space between the head and the recess surface to form a secure bond. 
     In one embodiment an inwardly extending lip is provided along the recess opening. The lip serves to ensure that the solid adhesive stays within the recess during curing. In addition, if the bond between the adhesive and the fastener head and the recess surface fails, the lip traps the solid adhesive within the recess. 
     In one aspect a boss extension may be provided within the recess to maintain a space between the portion of the recess surface adjacent the boss and the fastener. Thus, another object is to provide a locking device of the above kind where adhesive contacts a large surface area of each of the recess and fastener surfaces thus forming a superior bond. 
     In one aspect the recess is defined by a recess surface that includes at least one radial incongruity wherein the phrase “radial incongruity” means that, given alignment of the recess with a fastener aperture, from the perspective of the aperture at least one portion of the surface is different than other portions. For example, in some embodiments the recess may form a main cavity and one or more lateral cavities that open into the main cavity. As another example the recess may define an extension into an otherwise cylindrical recess. The in-congruous surface or segment or member operates, in conjunction with the solid adhesive, to mechanically restrain the fastener. Also, in this regard, the apparatus is especially useful in conjunction with fasteners where the fastener portion received within the recess includes a radial incongruity. 
     In one embodiment the extending segment includes first, second and third extending segments, each of the extending segments being an essentially elongated flat member, the first extending segment linked to the secure segment at one end, the second extending segment extending from an end of the first extending segment opposite the securing segment, essentially perpendicular to the first extending segment and to the side of the first extending segment on which the recess opens, the third extending segment extending from an end of the second extending segment opposite the first extending segment and essentially parallel to the first extending segment, the third extending segment forming the restraining surface. 
     The invention also includes an apparatus for use with first and second. fasteners and a receiving member, each fastener including a first end and a threaded extension that extends from the first end, the first ends forming first and second essentially oppositely facing surfaces that define a first dimension. In this embodiment the apparatus is for restraining rotation of the fasteners when the extensions are received within apertures. 
     Here the apparatus comprises a bracket member including first, second and third integrally linked extending members, each of the first and third members including proximal and distal ends and forming first and second facing recesses at the distal ends, respectively, the second member linked at opposite ends to the first and third member proximal ends, respectively, the second distal ends defining a second dimension and preferably, where boss extensions are included, the boss extensions form the second dimension. 
     The apparatus also includes a bonding material that becomes solid and flexible upon curing, the bonding material provided within the recesses. With the threaded members received within the apertures and un-cured bonding material within the recesses the bracket member is positionable such that the first ends of the first and second fasteners are receivable within the recesses. Preferably the second dimension is less than the first dimension. 
     The invention also includes a method for use with a fastener and a receiving member, the fastener including a first end and a threaded extension that extends from the first end, the receiving member forming an aperture along an axis for threadably receiving the extension and also forming at least a first surface that is essentially parallel to the axis and that is at least in part non-concentric with the aperture, the threaded member removable from the aperture via rotation in a first direction. The method is for restraining rotation of the fastener when the extension is received within the aperture. The method comprises the steps of providing a bracket member including at least a securing segment and an extending segment that are integrally linked, the securing segment forming a recess, the extending segment extending laterally from the securing segment and forming a restraining surface; placing a fluid bonding material that becomes solid and flexible upon curing within the recess; with the threaded member received within the aperture, positioning the bracket such that the first end is receivable within the recess and the restraining surface contacts the first surface, the surfaces together restrain rotation of the bracket member in the first direction about the axis; and allowing the bonding material to cure. 
     Furthermore the invention includes a method for use with first and second fasteners and a receiving member, each fastener including a first end and a threaded extension that extends from the first end, the receiving member forming first and second essentially oppositely facing surfaces and the first ends defining a first dimension. The receiving member also forming first and second apertures along first and second essentially parallel axis for threadably receiving the first and second fastener extensions, respectively. The method is for restraining rotation of the fasteners when the extensions are received within the apertures. The method comprises the steps of: providing a bracket member including first, second and third integrally linked extending members, each of the first and third members including proximal and distal ends and forming first and second facing recesses at the distal ends, respectively, the second member linked at opposite ends to the first and third member proximal ends, respectively, the second distal ends defining a second dimension when the bracket is in an unstressed state; placing a fluid bonding material that becomes solid and flexible upon curing within the recesses; with the threaded members received within the apertures, positioning the bracket such that the first ends of the first and second fasteners are receivable within the recesses; and allowing the bonding material to cure. 
     Thus, one other object is to provide a bracket device that can lock more than one threaded fastener in place. 
     These and other objects, advantages and aspects of the invention will become apparent from the following description. In the description, reference is made to the accompanying drawings which form a part thereof, and in which there is shown a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention and reference is made therefor, to the claims herein for interpreting the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a perspective view of a restricting device according to the present invention; 
     FIG. 2 is partial view of a portion of the device of FIG. 1 with an adhesive provided in a recess; 
     FIG. 3 is a side elevational view of the device of FIG. 1 adjacent a receiving member and two fastening members; 
     FIG. 4 is similar to FIG. 3 albeit illustrating the device secured to the fasteners and receiving member of FIG. 3; 
     FIG. 5 is a partial cross sectional view of the configuration of FIG. 4; 
     FIG. 6 is a cross sectional view taken along the line  6 — 6  of FIG. 5; 
     FIG. 7 is a perspective view of another embodiment of the inventive device; 
     FIG. 8 is a perspective view of one other embodiment of the invention; and 
     FIG. 9 is a schematic illustrating radial congruity and incongruity. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the Figures and more particularly to FIG. 1, an inventive restraining device  10  comprises a bracket including first, second and third essentially flat and elongated segments  11 ,  13  and  15  that are linked together to form an essentially “C” shaped device. To this end first segment  11  includes distal and proximal ends  20  and  22 , respectively, third segment  15  includes distal and proximal ends  24  and  26 , respectively, second segment  13  includes opposite ends  28  and  30 , first segment proximal end  22  is integrally linked to end  30  and proximal end  26  is linked to end  28  and segments  11  and  15  extend to the same side of second segment  13 . 
     Although not necessary, the illustrated embodiment first and third segments  11  and  15  are linked to second segment  13  via curved segments  32  and  34 , respectively, to provide a relatively more finished appearance. At the end of first segment  11  a securing segment  36  is provided. Importantly, securing segment  36  forms an essentially cylindrical recess  38  facing third segment  15 . Recess  38  includes a main recess  40  and two laterally extending recesses  42  and  44  that open into main recess  40 . Inside main recess  40  an extension boss  46  extends toward third segment  15  and has a relatively short length such that the end of boss  46  is well within recess  38 . Referring to FIGS. 1 and 5, securing segment  36  forms a lip,  48  around the entire opening of recess  38  that extends inwardly. The distal end  24  of third segment  15  also forms a securing segment  49 . Referring also to FIG. 3, segment  48 , like segment  36 , forms a recess  138  including a main recess and two laterally extending recesses (not illustrated in FIG.  3 ), a boss and a lip. Although the construction of recess  138  is not illustrated in detail it should be recognized that in the present example recess  138  would include elements likes main recess  40 , lateral recesses  42  and  44 , boss  46  and lip  48 , as illustrated in FIG.  1 . Recess  138  faces first segment  11 . 
     Device  10  is preferably constructed of a moldable, non-conductive, low modulus material so that the material prevents adverse interactions with internal electrical circuits while allowing segments  11 ,  13  and  15  to be bent and flexed for easy installation, preferably, to provide a clamping force when installed. 
     Referring now to FIGS. 1 and 2, in addition to device  10 , the present invention employs a bonding material, preferably a polyurethane adhesive, that is initially in a liquid or fluid form and that cures to form a solid flexible bonding “insert” or member. The adhesive forms a bond between the internal surface of recess  38  and the head or an end of a threaded fastener as will be described in more detail below. In FIG. 2, recess  38 , including main recess  40  and lateral recess  42  and  44  are shown filled with a the non-cured liquid adhesive. 
     Referring now to FIG. 3, a receiving member  70  including a base member  72  and two connecting members  74  and  76  is illustrated. In addition, two threaded fasteners  78  and  80  in the form of two screws are also illustrated. Fastener  78  includes a hexagonal head member  82  and an extending member  84  while screw  80  includes head member  86  and a threaded extending member  88 . Screws  82  and  86  are provided to secure members  74  and  76  to member  72 . When members  74  and  76  are positioned as illustrated, members  72 ,  74  and  76  together form receiving member  70  which defines two apertures  75  and  77  that extend along essentially parallel aperture axis  79  and  81  respectively. Extending members  84  and  88  are threadably received within apertures  75  and  77  such that the oppositely facing surfaces of heads  82  and  86  define a first dimensions D 1 . 
     As best seen in FIG. 3, the distance between facing boss extensions  46  (see also FIG. 1) and  146  within opposing recesses  38  and  138  define a second dimension D 2 . Second dimension D 2  is slightly less than first dimension D 1  so that, when device  10  is used to clamp-screws  78  and  80  in place axial pressure is applies to heads  82  and  86  as described below. 
     Referring now to FIGS. 1,  2  and  3 , in order to use device  10  to restrict rotation of screws  78  and  80 , an adhesive  60  is provided within each recess  38  and  138 . Next, as best illustrated in FIG. 3, first and second segments  11  and  15  are pulled or flexed apart in the direction of arrows  90  and  92  thereby causing the dimension D 2  between boss extensions  46  and  146  to exceed the dimension D 1  between oppositely facing surfaces of heads  82  and  86 . 
     Referring still to FIG.  3  and also to FIG. 4, device  10  is positioned such that screw heads  80  and  82  are adjacent recesses  38  and  138  and then device  10  is de-stressed thereby allowing the device to spring back toward its natural state. Because dimension D 1  is less than dimension D 2 , device  10  places a clamping force on heads  82  and  86 . 
     Referring now to FIGS. 4 and 5, with device  10  so positioned, boss  46  contacts an upper surface  102  of head  82  thereby causing a gap  104  to exist between a recess wall  106  and surface  102 . Thus, a layer of adhesive  108  fills gap  106 . In addition, adhesive fills the gap between lateral surfaces of head  82  and the other recess surfaces as illustrated. Referring also to FIG. 2, the adhesive extends into lateral recesses  42  and  44  and fills up to lip  48 . 
     After device  10  has been positioned as described above, the adhesive is allowed to cure so that the adhesive becomes a solid flexible member  110  inside recess  38 . A similar flexible member (not illustrated) is formed within recess  138 . 
     After the adhesive cures, the adhesive restricts fastener rotation in two ways. First, because the adhesive preferably adheres to each of head  82  and the internal surface of recess  38 , the adhesive bonding should restrict rotation. Second, even if one or both of the adhesive bonds between member  110  and head  82  or member  110  and the internal surface of recess  38  is not formed or deteriorates over time, member  110  is solid and flexible and should act as a mechanical jamb between head  82  and lateral recess walls. To this end, see FIG. 6 which shows cured member  110  that completely fills the space between recess wall  112  and head wall  114 . 
     While a single embodiment is illustrated and described above clearly many other embodiments are contemplated by the present invention. For example, referring now to FIG. 7, a device  210  bis illustrated for restricting rotation of a single threaded fastener In this case, referring also to FIG. 1, device  210  is essentially identical to first segment  11  including a rigid member which forms a recess  238  akin to recess  38  and lateral recesses  242  and  244  akin to lateral recesses  42  and  44 . In addition, although not illustrated, device  210  may also include a boss  46 . Device  210  extends laterally from recess  238  and includes at least one restricting surface  250 . In this case receiving member  252  includes at least a first surface that is essentially parallel to an aperture access  256  and that is at least in part non-concentric with the aperture that receives fastener  260  shown in phantom. In this case non-concentric means a surface that includes portions that are different distances from the axis  256 . Thus, for example, a cylindrical surface or a dome shaped surface centered on axis  256  would not be non-cylindrical whereas a planar surface extending parallel to aperture  256  as illustrated would be non-concentric. 
     Referring still to FIG. 7, to restrict rotation of fastener  260 , adhesive is provided within recess  238  and a head portion of fastener  260  is received within the recess  238  with restricting surface  250  placed against first surface  254  where a loosening direction of fastener rotation is in the clockwise direction. In this case, after the adhesive cures and forms a solid and flexible member within recess  238 , fastener rotation is essentially eliminated. 
     Referring now to FIG. 8, a third embodiment of the present invention is illustrated. Referring also to FIG. 1, the device  310  in FIG. 8 is similar to a device including only first and second segments  11  and  13  wherein a first segment  312  is akin to segment  11  and a second segment  314  is akin to segment  13 . In addition, a recess  338  formed by segment  312  is essentially identical to the recesses described above and the fastener secured by the device  310  is essentially identical to the fastener described above. In the embodiment of FIG. 8, second segment  314  extends at a right angle to first segment  312  and, when secured and adhered to the head of fastener  360 , second segment  314  bends around a corner of a receiving member  362  and includes a restricting surface  340  that contacts a first surface  342  of member  362 . When an adhesive within recess  338  cures, surfaces  340  and  342  restrict rotation of fastener  360 . In this embodiment surface  342  is non-concentric with an aperture recess (not illustrated). 
     It should be appreciated that the methods and apparatuses described above are only exemplary and do not limit the scope of the invention, and that various modifications could be made by those skilled in the art that would fall under the scope of the invention. For example, while three different shapes of restricting devices are illustrated above, clearly the shape of the restricting device can be modified depending upon the relative position of a threaded fastener with respect to the device, the relative positions of walls or other stationary objects to which the device is coupled and other considerations. Thus, the length of any of segments  11 ,  13  or  15  in FIG. 1 could be modified. 
     In addition, while one recess  38  configuration is illustrated and one fastener first end in the form of a hexagon shape is illustrated above, clearly the invention contemplates virtually all other recess and first end shapes. Moreover, to provide a mechanical restraint as well as the adhesive restraint, preferably each of the first end and recess configurations should include radial incongruities. To this end referring now to FIG. 9 a radial incongruity is best understood by a definition of what a radial incongruity is not. In FIG. 9 a receiving member  350  includes a surface  352  within a plane (also  352 ) and defines a threaded aperture  354  about an aperture axis  356 . 
     Referring still to FIG. 9, a curve  372  is illustrated which is dissected by axis  356  so that axis  356  and the right side of curve  372  define a shape  374 . If shape  374  is rotated about axis  356  to define a three dimensional surface the resulting surface will be radially congruent. However, if the shape defined by any portion of a surface  372  and axis  356  is different than any other shape defined by a different portion of a surface  372  and axis  356 , the resulting three dimensional surface is radially in-congruent. For example, in FIG. 9 the phantom line shows an in-congruity. 
     To apprise the public of the scope of this invention, the following claims are made: