Patent Abstract:
The locking nut and bolt system includes an elongated locking unit, mounted in a nut and operative with a specially configured groove bolt. The locking unit includes a plurality of at least three tines, asymmetrically located, which protrude tangentially and generally radially inward. The tines are radially asymmetrically disposed such that when a respective tine latches into a corresponding groove, asynchronous locking operation is achieved. When the tine is engaged in the groove, counter-rotational movement (loosening) is prohibited. In another embodiment, the locking unit has different sized edge cut-outs prohibiting the locking insert from rotating within the nut. The locking unit may also include a longitudinal split and a key and a keyway. A manufacturing process is also disclosed.

Full Description:
The present invention relates to a locking nut and bolt system and a locking nut insert utilized in connection with a specially configured bolt to provide enhanced locking or resistance to counter-rotative motion. A manufacturing process for the locking unit insert is also disclosed. 
   BACKGROUND OF THE INVENTION 
   Nut and bolt systems typically compress elements therebetween and mount one component to another component. Sometimes, the mounted assembly is subjected to vibrations which cause counter-rotative torque on the nut and bolt such that the nut loosens on the bolt and the components forming the assembly become loose and unattached. It is helpful to have a locking nut and bolt system and a locking nut insert (operable in conjunction with a specially configured bolt) which prohibits counter-rotative movement and therefore maintains the components in a mounted or fixed assembly. 
   Various locking nut and bolt systems are disclosed in U.S. Pat. No. 6,010,289 to DiStasio; U.S. Pat. No. RE35,937 to DiStasio; and U.S. Pat. No. 5,951,224 to DiStasio. The content and specification of U.S. Pat. No. 6,010,289 is incorporated herein by reference thereto. U.S. Pat. No. 307,722 to Klemroth discloses bolts having grooves thereon. The following patents disclose the use of bolts carrying grooves and one or more locking tines operative with the grooves on the bolts to prevent or limit loosening of the nut and bolt: U.S. Pat. No. 1,136,310 to Burnett; U.S. Pat. No. 1,226,143 to Stubblefield; U.S. Pat. No. 2,521,257 to Sample; and U.S. Pat. No. 5,238,342 to Stencel. 
   OBJECTS OF THE INVENTION 
   It is an object of the present invention to provide a locking nut and bolt system (and a locking nut insert) wherein the locking nut insert carries a plurality of locking tines which are not radially symmetrical to each other, thereby enhancing the locking characteristic of the locking nut and bolt system. 
   It is a further object of the present invention to provide a locking nut and bolt system (and a locking nut insert) wherein the insert is better fixed within the nut due to half-moon cut-out edge segments. 
   It is a further object of the present invention to provide a locking nut and bolt system with enhanced locking features wherein the locking action of a respective tine in a corresponding bolt groove is asynchronous with respect to other tines and other grooves on the locking unit insert and the bolt, respectively. 
   It is a further object of the present invention to provide a locking nut insert which is longitudinally split to enhance handling and manufacturing characteristics of the locking unit insert. 
   SUMMARY OF THE INVENTION 
   The locking nut and bolt system includes a specially configured bolt operative with an elongated locking unit, which locking unit is mounted in a recess defined on an end face of a nut. The bolt carries a plurality of notches on its threads, which notches are in a predetermined pattern generally longitudinal (which may include spiral or diagonal configurations). The elongated locking unit includes a plurality of at least three tines (in one embodiment) which protrude tangentially and generally radially inward towards the axial centerline of the bolt. The tines, in one embodiment, are radially asymmetrically disposed about the axial centerline such that when a respective tine latches into a corresponding groove, asynchronous locking operation is achieved with respect to the remaining tines and grooves. When the tine falls within the groove, counter-rotational movement (suggesting a loosening of the nut and bolt) is prohibited due to abutment of the distal tine end against the lock face of the groove. In another embodiment, the elongated locking unit has half-moon cut-out edge segments that are swaged to the nut thereby prohibiting the locking unit insert from rotating within the nut recess. Further enhancements include configuring the locking unit as one of an elongated cylinder or an elongated polygonal unit having five or more sides. The elongated locking unit also includes a longitudinal split which enhances handling and manufacture of the locking unit insert. The split may be formed by interleaved surfaces which define opposing sides of the longitudinal split. A key and a keyway may also be formed on the interleaved surfaces. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further objects and advantages of the present invention can be found in the description of the preferred embodiments which follows and in the accompanying drawings which show: 
       FIG. 1   a  diagrammatically illustrates a locking nut and bolt system with the bolt having a straight longitudinal groove thereon; 
       FIG. 1   b  diagrammatically shows a cross-sectional view of the grooved bolt; 
       FIG. 2  diagrammatically illustrates a grooved bolt with a spiral or somewhat diagonally positioned groove or notched region; 
       FIGS. 3   a  and  3   b  diagrammatically illustrate a perspective view of the locking unit insert and a nut thread axial end view of the locking insert, respectively; 
       FIG. 4  diagrammatically illustrates a plan view of the locking unit insert; 
       FIG. 5  diagrammatically illustrates a locking unit insert cooperating with a grooved bolt (CR denoting counter-rotative or loosening force) or direction; 
       FIG. 6A  diagrammatically illustrates a detail view of a tine falling into a notch in the notched or grooved bolt; 
       FIGS. 7   a  and  7   b  diagrammatically illustrate a portion of the nut, nut recess and a wall segment of the locking nut insert as well as the swage mount of the insert on the nut; 
       FIG. 8  diagrammatically illustrates a perspective view of the locking unit insert placed in a nut recess prior to swaging; and 
       FIGS. 9   a  and  9   b  diagrammatically illustrate polygonal locking inserts representing embodiments of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention relates to a locking nut and bolt system (including a locking nut insert) with enhanced locking capabilities. A manufacturing process is also described for the locking unit insert. 
     FIG. 1   a  diagrammatically illustrates a bolt  20  having a bolt head  22  and a bolt stem  24 . Bolt  20  includes threads which include thread crests  26  and thread troughs  28 . Nut  40  includes a plurality of threads which are complementary to the thread system  26 ,  28  on bolt stem  24 . Axial centerline  60  is related to the axial centerline of the bolt  20  as well as nut  40 . Axial thread end  31  is also shown in  FIG. 1   a . Reference to an outboard position of the locking nut insert (not shown in  FIG. 1   a ) refers to items closer to axial thread end  31 . The term “inboard” refers to items closer to bolt head  22 . 
     FIG. 1   b  diagrammatically shows a cross-sectional view of grooved bolt  20 . Particularly, thread crest  26  includes a generally longitudinal groove  34  thereat. Groove  34  includes a leading surface  38  and a locking surface  36 . Groove  34 , in a preferred embodiment, does not exceed the thread trough or root  32  of the thread system  26 ,  28 . This feature reduces stress fractures which may occur if the groove or notch is deeper than root  32 . 
     FIG. 2  diagrammatically illustrates a diagonal or a spiral groove  43  on bolt thread  45 . Axial centerline D′–D″ is also shown in  FIG. 2 . It should be noted that bolt  20  may contain a plurality of grooves as shown in connection with bolt  20  in  FIG. 5 . Further, these grooves are generally longitudinally disposed in a predetermined pattern, which pattern may be limited to a portion of the longitudinal aspect of bolt  20 . In  FIG. 1   a , groove  34  does not extend the entire thread portion  26 ,  28  of bolt  20 . In other embodiments, the groove may extend the entire thread. Further, adjacent grooves formed on thread crests are generally longitudinally adjacent each other even if slightly arcuately displaced with respect to each other as shown in conjunction with the spiral groove  43  in  FIG. 2 . 
     FIGS. 3   a  and  3   b  diagrammatically illustrate a perspective view and a thread end axial view of locking unit insert  50 . Locking unit insert  50  is generally cylindrically shaped (but see  FIG. 11   a  for a different shape) and includes a plurality of at least three tines  52  which are protruding tangentially and generally radially inward towards the axial centerline of the locking nut and bolt system. Tine  52  includes a distal tine end  54  and a proximal base region  56 , which base is attached to or formed by tine wall  58 . Similar numbers designate similar items throughout the figures. 
   As shown in  FIG. 4 , a plan view of locking unit insert  50 , tines  52  are formed by cutting or stamping a U-shape on a strip of metal. Although metal is used in the preferred embodiment, other materials may be employed. In the preferred embodiment, locking unit insert  50  includes a longitudinal split  62  extending the axial length of unit  50 . In a further enhancement, split  62  is formed by opposing sides  64 ,  66 . In an enhancement, opposing side  64  forms a key which fits within opposite side  66  forming a keyway. In this manner, key  64  aligns with keyway  66  to form split  62 . Also, the locking unit insert can be slightly compressed thereby reducing its diameter to facilitate insertion of the locking unit into a recess in the nut end face discussed later in conjunction with  FIG. 10 . In  FIG. 3   b , split  62  is seen as split portion  62   b.    
   To manufacture locking insert  50 , a flat plate is cut per the plan view in  FIG. 4  including stamp-cut tines  52  and key and keyway edge surfaces  64 ,  66 . Then the plate is rolled such that key  64  is folded into keyway  66 . See  FIG. 3   a . Also, tines  52  are radially inwardly compressed or punched upward from the plate to form the radial tines. The order of plate rolling and punching tines is not critical. 
   To ensure that the locking unit  50  does not rotate within nut recess, the locking unit on outboard edge  68  includes at least two cut-outs  70 ,  72 . These cut-outs are sometimes called herein different sized half-moon cut-out edge segments. Also, cut-outs may be cavities formed by any cutting or forming process. Each cut-out  70 ,  72  has a different arcuate length a, b, which further enhances handling of the locking unit insert  50 . In addition, cut-outs  70 ,  72  are placed intermediate the various positions of locking tines  52 . The intermediate position of the mounting lock cut-outs  70 ,  72  reduces stress and fatigue in the insert during use. 
   One aspect of the present invention is that the locking tines are radially asymmetrically disposed on locking unit  50 . In other words, distance E between the left side tines  52  is different than distance F between the intermediate tine and the right side tine  52 . 
     FIG. 5  shows the radially asymmetrical configuration of tines  52   a ,  52   b , and  52   c . Further, the locking nature of tine  52   a  is asynchronous with respect to the same locking operations of tine  52   b  and tine  52   c . In other words, when tine  52   a  locks, tines  52   b  and  52   c  are riding on thread crests or lands  35   b  and  35   c . In a similar manner, when tine  52   b  locks in groove  34   b , tine  52   c  is riding on crest or land  35   c . At that time during counter-rotation CR movement of bolt  21  with respect to locking insert  50 , tine  52   a  is on the adjacent left land. Current testing of the locking nut and bolt system indicates that a single tine is sufficient to prevent counter-rotative movement of bolt  21  with respect to locking nut insert  50 . Therefore, radially asymmetric disposition of the tines with respect to each other about the axial centerline is adequate to lock the nut and bolt. Radially asymmetrical disposition is achieved if the arcuate distance between tines  52   a – 52   b  is different than the arcuate distance between tines  52   b  and  52   c . In one working embodiment, the arcuate distance between tines  52   a – 52   b  is the same as the arcuate distance between tines  52   a – 52   c , that being 106.7 degrees for a ⅜ inch bolt. However, since the arcuate distance  52   b – 52   c  is not the same as distance  52   a – 52   b  (or  52   a – 52   c ), asymmetrical positioning is achieved, resulting in the asynchronous locking of the plurality of tines in the plurality of notches. The tines are not symmetrically located about the axial centerline because  52   b – 52   c  is a different arcuate distance than  52   a – 52   b  or  52   a – 52   c . Other asymmetrical positions may be utilized. 
     FIG. 6A  diagrammatically shows that tine  52   a  is operative in a locking position in groove  34   a . By altering the number of tines and the number of grooves and providing radially asymmetric placement of the tines about the axial centerline, locking action is achieved with a minimal rotational movement in the counter-rotational direction CR (loosening or unscrewing direction). Further, a calculation can establish the maximum unlock arcuate movement necessary before any particular tine falls and locks into a corresponding locking face  36  of a groove. This maximum unlock arcuate distance translates into the maximum seat torque load lost due to counter-rotative movement. Asymmetrical tine placement reduces seat torque load losses. Also, alternatively, asynchronous locking of one tine with respect to others reduces seat torque load losses. 
   A plurality of tines greater than three may be utilized in radially asymmetric positioning. A plurality of grooves or notches on the bolt thread may also be utilized. 
     FIGS. 7   a  and  7   b  diagrammatically show a cross-section of nut  80  having a nut end face  82 .  FIG. 9A  shows wall segment  81  of locking nut insert  50 . Nut end face  82  has a small build up area  84 . Build up area  84  is subsequently crushed or swaged to capture wall segment  81 . The swaged area  84   b  is shown in  FIG. 7   b.    
     FIG. 8  diagrammatically shows locking nut insert  50  placed within recess  86  of nut  80 . Build up area  84  has not been swaged upon half-moon cut-out edge segment  70  of locking nut insert  50 . As is known in the art, nut threads  81  are complementary to bolt threads  26 ,  28  in  FIG. 1   a . The utilization of outboard cut-out edge segment  70  enables the locking nut insert  50  to be firmly locked or swaged or mounted in nut  80 . The locking of the locking nut insert  50  in nut  80  is important in that the insert should not rotate when the tine falls within the corresponding groove during the prohibition of counter-rotational movement. By utilizing an inboard cut-out edge segment (not shown), additional locking forces are established for the locking nut insert. 
     FIGS. 9   a  and  9   b  diagrammatically show locking unit inserts  90  and  92 . These inserts have longitudinal splits  93 . Locking inserts  90 ,  92  are shaped as polygons having at least five or more sides. The polygonal shapes enhance handling of the locking nut inserts and insertion into nut recesses  86 . 
   In  FIG. 11   b , inboard edge  94  has been crimped inward to form a radial ledge. This radial ledge may also enhance handling of the locking nut insert during manufacture. Of course, the locking nut insert is mechanically handled by machines and inserted into nut recess  86 . By utilizing radial ledge  94  and detecting radial ledge  94 , the locking insert  92  can be properly placed into nut recess  86 . The utilization of different sized cut-outs  70 ,  72  shown in  FIG. 4  also enhances handling since the machines can detect the edge  68  having cut-outs  70 ,  72  as compared with inboard edge which is opposite edge  68 . Proper insertion of the locking nut inserts into nut recess  86  is important. If the locking nut inserts are placed in nut recess  86  “upside down,” locking is not achieved in the counter-rotational movement direction. 
   The claims appended hereto are meant to cover modifications and changes within the scope and spirit of the present invention.

Technology Classification (CPC): 5