Patent Publication Number: US-2006013672-A1

Title: Flex lock nut having an annular recess

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention relates to lock nuts. Specifically, the present invention relates to flex lock nut having an annular recess.  
      2. Description of the Related Art  
      The use of fastening nuts upon threaded bolts is common in many industries. Since nuts are subjected to extreme vibrations, dynamic loads, shock and stresses, the nuts are susceptible to loosening. Locking nuts are commonly used to lock a nut in place upon the threaded bolt. When lock nuts are twisted far enough onto a bolt, the lock nuts are locked into place. A common existing locking nut utilized is a “flex lock” nut.  FIG. 1  is a partial cut-away view in elevation of an existing flex lock nut  10  positioned on a threaded bolt  12 . The flex lock nut  10  includes a collar section  14  having a plurality of slotted segments  16 . As the nut is twisted on the bolt, the slotted segments expand outwardly, thereby locking the nut in place.  FIG. 2  illustrates a top plan view of the flex lock nut  10  prior to seating the nut on a bolt (not shown).  FIG. 3  is a top plan view of the flex lock nut  10  in a fully locked position. As the threaded bolt enters the “locking area,” the slotted segments expand and the nut locks.  
      Although there are no known prior art teachings of an apparatus as that disclosed herein, prior art references that discuss subject matter that bears some relation to matters discussed herein are U.S. Pat. No. 2,299,085 to Gade (Gade) and U.S. Pat. No. 3,342,233 to Meisel.  
      Gade discloses a self-locking nut having a plurality of segments. When the nut is threaded onto its companion bolt, the segments bear resiliently upon the bolt and create additional friction to lock the nut in place. Meisel also discloses a self-locking nut having a plurality of segments, which are used to lock the nut in position upon the bolt.  
      However, none of the prior art references, including the existing flex lock nut, teaches or suggests a segmented collar portion having an annular recess located on a bottom portion of the nut. A flex lock nut is needed which includes an annular recess to provide an additional locking feature.  
      Thus, it would be a distinct advantage to have a flex lock nut, which incorporates both a segmented collar portion and an annular recess to provide two locking features. It is an object of the present invention to provide such an apparatus.  
     SUMMARY OF THE INVENTION  
      In one aspect, the present invention is a lock nut having a nut body with a threaded bore running from an upper end to a lower end of the nut body. Several slotted segments extend from a collar portion on the upper end of the nut body. The slotted segments are substantially coaxial with the bore. An annular recess is positioned upon a bottom end of the nut body. The annular recess is coaxial with the threaded portion of the bore. The slotted segments expand when the nut body is seated upon a threaded bolt to provide an upper locking friction to prevent rotation of the nut body. The annular recess also deforms when the nut body is seated upon the threaded bolt to provide a lower locking friction to prevent rotation of the nut body.  
      In another aspect, the present invention is a lock nut having a nut body. The nut body includes a threaded bore running from an upper end to a lower end of the nut body. The nut body includes six planar exterior surfaces to provide a hexagonal shape to the nut body. A collar portion is located on the upper end of the nut body. The collar portion has a diameter smaller than the nut body. In addition, six slotted segments extend from the collar portion. Each segment is aligned with one of the planar exterior surfaces. The slotted segments form a threaded interior and are coaxially aligned with the bore. An annular recess is positioned upon the bottom end of the nut body. The annular recess is circumferentially positioned on an outer perimeter of the bore at the bottom end of the nut body. The slotted segments expand when the nut body is positioned upon a threaded bolt to provide an upper locking friction to prevent rotation of the nut body. The annular recess also deforms when the nut body is seated upon the threaded bolt to provide a lower locking friction to prevent rotation of the nut body.  
      In still another aspect, the present invention is a lock nut having a six-sided nut body with a threaded bore running from an upper portion to a lower portion of the nut body. Six slotted segments extend from the upper portion of the nut body and form a collar portion. The collar portion has a smaller diameter than the nut body. An annular recess is positioned on a perimeter about the bore at the lower portion of the nut body. The slotted segments expand to provide an upper locking frictional force upon a bolt being threaded within the bore. In addition, the annular recess deforms to provide a lower locking force upon the bolt as the nut body is seated upon the bolt, thereby preventing inadvertent rotation of the lock nut.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  (Prior Art) illustrates a view in elevation of a flex lock nut;  
       FIG. 2  (Prior Art) illustrates a top plan view of the flex lock nut prior to seating the nut on a bolt;  
       FIG. 3  (Prior Art) is a top plan view of the flex lock nut in a fully locked position;  
       FIG. 4  is a view in elevation of a flex lock nut  20  in the preferred embodiment of the present invention;  
       FIG. 5  illustrates a top plan view of the flex lock nut  20  of  FIG. 4 ; and  
       FIG. 6  is a bottom view of the flex lock nut  20  of  FIG. 4 . 
    
    
     DESCRIPTION OF THE INVENTION  
      A flex lock nut having an annular recess is disclosed.  FIG. 4  is a view in elevation of a flex lock nut  20  in the preferred embodiment of the present invention. The flex lock nut  20  is a one-piece reusable prevailing torque lock nut with a plurality of slotted and threaded segments  22 . In the preferred embodiment of the present invention, there are six segments. However, it should be understood that any number of segments may be utilized. The flex lock nut  20  includes a collar portion  24  having a smaller diameter than a main body  26 . Within the flex lock nut is a threaded bore  28 . As stated above, all the segments may include threads aligned with the threaded bore  28 . On a bottom end  30  from the collar portion is an annular recess  32 .  
       FIG. 5  illustrates a top plan view of the flex lock nut  20  of  FIG. 4 . Between each segment  22  is a slot  34 . As is typical with flex lock nuts, the collar portion preferably includes a diameter smaller than the main body  26 . The main body may include a conventional hexagonal shape.  
       FIG. 6  is a bottom view of the flex lock nut  20  of  FIG. 4 . The flex lock nut includes the annular recess  32  located on a perimeter of the threaded bore  28 .  
      With the addition of the annular recess  28 , the flex lock nut  20  provides an additional and unique locking feature not available with existing flex lock nuts. With reference to  FIGS. 4-6 , the operation of the flex lock nut  20  will now be explained. The nut is seated upon a bolt (not shown). As the nut is torqued down further upon a bolt, the recess is flattened downwardly, thereby deforming the entire nut. Axis B ( FIG. 4 ) illustrates the gripping force provided by this deformation. As the recess is flattened, the axis B is pivoted inwardly toward the bore  28 . Because of the placement of the annular recess  32  upon the bottom portion of the nut, this deformation is far more than is seen in a conventional locking nut.  
      When continuous seating is applied, at the nut bearing surfaces, there are two locking features provided. First, the flex lock nut  20  provides an inside thread locking friction at the upper end as discussed with the flex lock nut  10  in the existing art. Axis A ( FIG. 4 ) illustrates the axis of the force exerted by this upper end locking feature. As illustrated, axis A pivots inwardly. Second, thread-locking friction is provided at an outside wall strength at the bottom end  30 , which moves inwardly to provide maximum locking grip at the upper end of the nut when tightened. This locking friction is depicted as Axis B in  FIG. 4 . These two locking features, prevailing torque locking feature at the upper end and seated locking feature at the bottom end, produces an enhanced locking grip for use in critical applications.  
      In particular, as the prevailing locking feature at the upper end of the flex lock nut  20  gets lighter after multiple uses, the recess locking feature on the bottom end  30  provides a constant inward grip on the upper end to reinforce the grip on the slotted portion of the nut and increase torque life of the prevailing locking feature on the upper end. This allows the flex lock nut  20  to be reused.  
      In addition, when there is a torque spread in the upper end locking feature, which is common with prevailing torque lock nuts, the recess locking feature in the bearing surface on the bottom end  32  supports the upper torque area, thereby preventing the upper torque area from getting lighter when seated.  
      The present invention provides advantages over existing flex lock nuts. The flex lock nut  20  provides two locking features, rather than merely one locking feature. The first locking feature is the prevailing locking feature on the upper end of the nut  20  which utilizing the grip of the segments as discussed in  FIGS. 1-3 . The second unique and novel locking feature is the recess locking feature locked on the bottom end of the nut. The annular recess is deformed when the flex lock nut  20  is seated upon a bolt. This deformation provides a locking feature as discussed above. These two locking features provide a useful locking nut, which may be reusable.  
      Thus, the present invention has been described herein with reference to a particular embodiment for a particular application. Those having ordinary skill in the art and access to the present teachings will recognize additional modifications, applications and embodiments within the scope thereof.  
      It is therefore intended by the appended claims to cover any and all such applications, modifications and embodiments within the scope of the present invention.