Abstract:
A plier having a wire twisting mechanism mounted on one handle with the opposing handle providing a multi tooth lock bar. A slide lock which actuates a spring retractable lock pawl is mounted on the twisting mechanism support. This arrangement allows locking of the plier handles when the proper jaw pressure is applied to varying thickness&#39; of safety wire or any other item held in the pliers grip. A squeeze of the handles retracts the law pawl and releases the pliers grip.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of the earlier filing dates of U.S. Provisional Patent Application No. 61/520,707 filed Jun. 14, 2011 and U.S. Provisional Patent Application No. 61/606,597 filed Mar. 5, 2012. The disclosures in aforementioned U.S. Provisional Patent Applications Nos. 61/520,707 and 61/606,597 are hereby incorporated herein in their entirety by this reference thereto. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a plier-type hand tool for twisting safety wire. 
       BACKGROUND OF THE INVENTION 
       [0003]    There are many prior patents related to wire twisting pliers some single direction twist pliers, and some reversible pliers that twist wire in a right or left direction. These prior patents lock the wire in the plier jaw with a single lock position. In U.S. Pat. No. 5,211,209 Geibel; a single lock position is shown. Wire twist pliers twist a variety of wire sizes depending on the job requirements. The most common sizes are 0.012″, 0.020″, 0.025″, 0.032″, 0.041″, and 0.051″. The prior art single lock position wire twist pliers work well with the smaller wire sizes. However, as the wire size increases, excessive jaw pressure is placed on the wire in order to lock the handles, making the handles difficult to lock and causing damage to the safety wire. This damage to the wire can cause premature failure of the safety wire in its application. 
       SUMMARY OF THE INVENTION 
       [0004]    This invention relates to plier-type hand tools, particularly to plier-type hand tools adapted to twist safety wire of various diameters. A multi-tooth soft lock mechanism allows the user of either a single direction wire twist plier or a reversible wire twist plier to place the exact amount of pressure desired to secure various wire sizes in the plier jaw for twisting. Digital intervention locks the handles together, retaining the grip. A squeeze of the handles automatically releases the wire. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The foregoing and other features of the invention will become more apparent upon a consideration of the following description taken in connection with the accompanying drawings wherein: 
           [0006]      FIG. 1  depicts a plan view of the soft lock wire twisting pliers  100  of this invention shown with the handles in the unlocked position; 
           [0007]      FIG. 1   a  depicts a plan view of the soft lock wire twisting pliers  100  of this invention shown with the handles in the locked position; 
           [0008]      FIG. 2  depicts an exploded view of the soft lock wire twisting pliers  100  of this invention with the lock pawl  130  removed; 
           [0009]      FIG. 2   a  depicts an end view of the twisting mechanism support  118  showing the lock bar guide  122 , lock pawl pivot hole  132  and lock pawl control pin slot  134 ; 
           [0010]      FIG. 2   b  depicts a side view of the twisting mechanism support  118  showing the lock bar guide  122 , lock pawl pivot hole  132  and lock pawl control pin slot  134 ; 
           [0011]      FIG. 3  depicts an exploded view of soft lock twisting pliers  100  of this invention showing the control arm release spring  138  and the actuating sleeve control arm  136 ; 
           [0012]      FIG. 4  depicts a perspective view of slide lock  146  three views of louvered finger grip  142  slide lock arm  136  opening in slide lock arm  140  which receives lock pawl control pin  128  and spring contact point  144 ; 
           [0013]      FIG. 5  depicts a cut away view from the jaw end of pliers showing the twisting mechanism support  118 , lock bar  120 , pawl  130 , and slide lock arm  136 ; 
           [0014]      FIG. 6  is a fragmentary schematic illustration, depicting the manner in which the soft lock wire twisting pliers  100  are utilized to grip end portions of one or more wires having relatively small diameters; 
           [0015]      FIG. 7  is a fragmentary schematic illustration, generally similar to  FIG. 6 , depicting the manner in which the soft lock wire twisting pliers  100  are utilized to grip end portions of one or more wires having a diameter which is larger than the diameter of the wire end portions illustrated in  FIG. 6 ; and 
           [0016]      FIG. 8  is a fragmentary schematic illustration, depicting the manner in which the soft lock wire twisting pliers  100  are utilized to grip end portions of one or more wires having diameters which are greater than the diameter of the wire end portions of  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    A soft lock wire twist plier is provided, which includes a pair of plier arms, each having a jaw portion with a grip/cutting area, and a handle portion pivotally interconnected and movable between an open position and a closed position. Either a single direction or reversible rotating means is mounted on one of the arms. A slide lock consisting of a louvered finger grip, slide lock arm, lock pawl and slide lock release spring are also positioned on the rotating means. The opposing plier arm supports a multi-tooth lock bar. When the desired holding pressure is placed on the safety wire in the plier jaws, the actuating sleeve is activated against spring pressure to move the pawl teeth into the lock bar teeth. The pressure is then reduced on the handles. The resulting tension keeps the pawl engaged in the lock bar. This holds the precise amount of pressure on the wire for twisting. The more the handles attempt to move outward, the tighter the pawls teeth pull into the lock bar. To release the wire, a squeeze of the handles allows the spring-loaded slide lock to release the lock pawl and hold it clear of the lock bar. 
         [0018]    The soft lock system also allows the plier to have many other uses other than twisting wire since the jaws may be locked in numerous positions. For example, the tool can be locked onto a washer so the washer can be placed over a screw in a confined area or the tool can be used as a clamp to hold items of varying thickness. 
         [0019]    The lock pawl is described as preferably having one to four teeth. More preferably two to four teeth. Most preferably two to three teeth. The lock bar is described as preferably having two to twelve teeth. More preferably having four to ten teeth. Most preferably having seven to nine teeth. 
         [0020]    The lock pawl&#39;s movement is limited by the elongated slot in the twisting mechanism which receives the lock pawl control pin. The pawl control pin also secures the slide lock arm in place. The pawl is held in place by flaring the end of the pawl pivot pin or by placing a retaining clip in a groove in the lock pawl pivot pin. 
         [0021]    A soft lock wire twisting plier or tool  100  constructed in accordance with the present invention is illustrated in  FIGS. 1 and 1   a . The tool  100  includes plier jaws or clamp members  104  which are connected with plier arms or handles  102  and  116 . The manually engagable plier arms or handles  102  and  116  extend from a pivot joint  200  in a direction away from the plier jaws or clamp members  104 . Each of the plier arms or handles  102  or  116  is integrally formed as one piece with one of the plier jaws or clamp members  104 . 
         [0022]    A known twisting mechanism  150  is disposed between the plier arms or handles  102  and  116 . The twisting mechanism  150  is fixedly secured to one of the plier arms, i.e., the plier arm  102 . A twisting mechanism support  118  ( FIG. 2 ) fixedly connects the twisting mechanism  150  to the plier arm  102 . Therefore, the twisting mechanism  150  moves with the plier arm  102  relative to the plier arm  116  during relative movement between the plier arms  102  and  116  to move the plier jaws  104  relative to each other. 
         [0023]    The twisting mechanism  150  ( FIGS. 1 and 2 ) has the same construction as is disclosed in U.S. Pat. No. 5,560,402. However, it is contemplated that the twisting mechanism may have a different construction. For example, the twisting mechanism  150  may have the construction as is disclosed in U.S. Pat. No. 5,211,209. 
         [0024]    The twisting mechanism support  118  connects the plier arm or handle  102  with the twisting mechanism  150 . The twisting mechanism  150  is disposed between the two plier arms or handles  102  and  116 . The path of movement of the plier arm or handle  116  relative to the plier arm or handle  102  during pivotal movement of the plier arm or handle  116  about the pivot joint  200 , extends through the twisting mechanism  150 . 
         [0025]    A central axis  204  ( FIG. 1 ) of the twisting mechanism  150  extends through the pivot joint  200  and intersects a central axis of the pivot joint. The central axis  204  of the twisting mechanism  150  is disposed in a plane containing the central axes of the plier arms or handles  102  and  116 . The plane containing the central axes of the plier arms  102  and  116  and the twisting mechanism  150  extends perpendicular to the central axis of the pivot joint  200 . 
         [0026]    The tool  100  has a general construction and mode of operation which is similar to the general construction and mode of operation of the wire twisting tools disclosed in U.S. Pat. Nos. 4,842,025; 5,211,209; and 5,560,402. The disclosures in the aforementioned U.S. Pat. Nos. 4,842,025; 5,211,209; and 5,560,402 are hereby incorporated herein in their entirety by reference. 
         [0027]    In accordance with one of the features of the present invention, a retainer mechanism  208  ( FIGS. 1-5 ) is provided to retain the plier jaws or clamp members  104  in any one of a plurality of positions, as a function of the thickness of one or more wires which are gripped by the plier jaws. The manner in which the retainer mechanism  208  holds the plier jaws or clamp members  104  in gripping engagement with a relatively thin wire  210  is illustrated schematically in  FIG. 6 . The manner in which the retainer mechanism  208  holds the plier jaws or clamp members  104  in gripping engagement with a wire  212  having a thickness which is greater than the thickness of the wire  210 , is illustrated schematically in  FIG. 7 . The manner in which the retainer mechanism  208  holds the plier jaws or clamp members  104  in gripping engagement with a wire  214  having a thickness which is greater than the thickness of the wire  212 , is illustrated schematically in  FIG. 8 . 
         [0028]    It should be understood that although only a single wire  210  has been illustrated in  FIG. 6 , it is contemplated that the plier jaws or clamp members  104  may engage portions of one or more wires. For example, opposite end portions  210  of a single relatively thin wire may be gripped by the plier jaws or clamp members  104 . Alternatively, end portions  210  of two separate wires may be gripped by the plier jaws or clamp members  104 . Similarly, two end portions of one or more wires  212  or  214  may be gripped by the plier jaws or clamp members  104  in the manner illustrated schematically in  FIGS. 7 and 8 . 
         [0029]    While two end portions of one or more wires  210 , or  212 , or  214  are gripped by the plier jaws or clamp members  104  in the manner illustrated schematically in  FIG. 6 , or  7 , or  8 , the twisting mechanism  150  is manually operated to twist the wire or wires in the manner disclosed in U.S. Pat. No. 4,665,953. The disclosure in the aforementioned U.S. Pat. No. 4,665,953 is hereby incorporated herein in its entirety by reference. 
         [0030]    The retainer mechanism  208  includes a lock pawl or retainer member  110  ( FIG. 1 ) which is engageable with a series  215  ( FIGS. 6-8 ) of retaining or locking teeth or locations  216 . The series of retaining or locking locations  216  are formed in a lock bar  120  which is fixedly connected with the plier arm or handle  116 . The series  215  of locking locations  216  are disposed in a linear array along one side of the lock bar  120 . Each of the retaining or locking locations  216  in the series  215  of locking locations is formed by one of a plurality of teeth formed in the lock bar  120  ( FIGS. 6-8 ). 
         [0031]    When the plier jaws or clamp members  104  engage the relatively thin wire  210  ( FIG. 6 ), the plier arm or handle  116  is displaced a relatively small distance downward (as viewed in  FIG. 6 ) from the plier arm or handle  102 . The teeth  218  on the lock pawl  110  engage teeth  216  in the series  215  of teeth on the lock bar. The lock bar teeth  216  engaged by the lock pawl teeth  218  are relatively close to the lower (as viewed in  FIG. 6 ) end portion of the lock bar  112 . Although the lock pawl or retainer member  110  has a plurality of teeth  218 , it is contemplated that the lock pawl may have a single tooth. 
         [0032]    When the plier jaws or clamp members  104  are to grip the relatively thin wire end portions  210 , the lock pawl  110  is moved to a disengaged condition ( FIG. 1 ) in which it is spaced from the series  214  of locking teeth  216 . The plier arms or handles  102  and  116  are then moved away from each other and the jaws  104  are moved to an open condition. The open plier jaws or clamp members  104  are positioned adjacent to opposite sides of the thin wire portions  210 . 
         [0033]    Pressure is then manually applied against the plier arms or handles  102  and  116  to close the plier jaws or clamp members  104  against opposite sides of the relatively thin wire end portions  210  ( FIG. 6 ). The manual force which is applied against the handles  102  and  116  is effective to resiliently deflect the handles through a short distance toward each other. The lock pawl  110  is then pivoted in a clockwise direction (as viewed in  FIGS. 1 and 6 ) about the pivot pin  114  ( FIGS. 1 ,  3 , and  5 ). This moves the teeth  218  ( FIG. 6 ) on the lock pawl  110  into engagement with teeth  216  on the lock bar  120  at a location relatively close to the lower end portion of the lock bar  120 . The teeth  218  on the lock pawl  110  engage teeth  216  which are relatively close to the lower end portion (as viewed in  FIG. 6 ) of the lock bar  120  because the plier arms or handles  102  and  116  have been manually squeezed together to cause the plier jaws or clamp members  104  to firmly grip the relatively thin wire end portions  210 . 
         [0034]    To pivot the lock pawl in a clockwise direction from the disengaged position of  FIG. 1  to the engaged position of  FIGS. 1   a  and  6 , a finger grip  142  on the slide lock  146  is manually moved toward the right (as viewed in  FIG. 1 ) along the twisting mechanism  150 . As this occurs, the slide lock control arm  136  ( FIG. 4 ) is moved toward right, as viewed in  FIGS. 3 and 4 . Manual force is transmitted from the slide lock  140  through the slide lock control arm  136 . This force is transmitted from a left (as viewed in  FIG. 4 ) side surface  220  of the opening  140  to the lock pawl control pin  128  ( FIGS. 3 and 5 ). This force is effective to pivot the lock pawl  110  in a clockwise direction from the disengaged position of  FIG. 1  to the engaged position of  FIG. 6 . As this occurs, the teeth  218  ( FIG. 6 ) the lock pawl  110  are firmly pressed into meshing engagement with the teeth  216  on the lock bar  120 . 
         [0035]    In the illustrated embodiment of the invention, the lock pawl  110  has a plurality (e.g., three) teeth  218  ( FIG. 6 ) which are moved into meshing engagement with the teeth  216  on the lock bar  120  under the influence of manual force transmitted through the slide lock control arm  136 . However, the lock pawl  110  may have either a greater or lesser number of teeth  218 . For example, the lock pawl  110  may have four or five teeth  218  if desired. As another example, the lock pawl  110  may have one or two teeth  218 . 
         [0036]    Once the teeth  218  on the lock pawl  110  have moved into meshing engagement with the teeth  216  on the lock bar  120  ( FIG. 6 ), the plier arms or handles  102  and  116  are manually released. The natural resilience of the plier arms or handles  102  and  116  causes them to tend to spring apart. This firmly presses the teeth  216  on the lock bar  120  against teeth  218  on the lock pawl  110 . The finger grip  142  ( FIG. 2 ) on the slide lock  106  is then manually released. 
         [0037]    At this time, the plier arms or handles  102  and  116  are still slightly deflected. The resiliently deflected plier arms or handles  102  and  116  press the teeth  116  on the lock bar  120  firmly against the teeth  218  on the lock pawl  110 . This results in the lock pawl  110  being maintained in the locking or engaged condition of  FIG. 6  against the influence of the force applied to the control arm  136  by the control arm release spring  138  ( FIG. 3 ). 
         [0038]    When the relatively thin wire portions  210  ( FIG. 6 ) are to be released, the plier arms or handles  102  and  116  are manually pressed toward each other. This eliminates the resilient downward (as viewed in  FIG. 6 ) force applied by the plier arms or handles  102  and  116  to the lock bar  120 . As this occurs, the teeth  216  on the lock bar are moved upwardly (as viewed in  FIG. 6 ) away from the teeth  218  on the lock pawl  110 . This results in the lock pawl  110  being released for pivotal movement in a counterclockwise direction under the influence of force applied against the control arm  136  by the release spring  138  ( FIG. 3 ). This allows the plier arms or handles  102  and  116  to move away from each other so that the plier jaws or gripper members  104  are opened and the wire portions  210  released. 
         [0039]    In  FIG. 6 , the tool  100  is being utilized to grip relatively thin wire portions  210 . In  FIG. 7 , the tool  100  is being utilized to grip wire portions  212  having a thickness (diameter) which is greater than the thickness of the wire portions  210 . When the wire jaws or clamp members  104  grip the wire end portions  212  ( FIG. 7 ), the wire jaws are separated by a greater distance than when thin wire portions  210  ( FIG. 6 ) are gripped. This results in the plier arms or handles  102  and  116  being separated by a greater distance when relatively thick wire end portions  212  are gripped ( FIG. 7 ) than when relatively thin wire end portions  210  ( FIG. 6 ) are gripped. 
         [0040]    Since the plier arms or handles  102  and  116  are separated further, the teeth  218  on the lock pawl  210  engage the teeth  216  on the lock bar  120  at a location which is displaced further from the lower (as viewed in  FIG. 7 ) plier arm or handle  116  than when the relatively thin wire end portions  210  ( FIG. 6 ) are gripped. This results in each tooth  218  on the lock pawl  110  engaging a different tooth on the lock bar  120  when the tool  100  is gripping relatively thick wire end portions  212  than when the tool is gripping relatively thin wire end portions  210 . 
         [0041]    In the embodiment of the invention illustrated in  FIG. 8 , the tool  100  is utilized to grip wire end portions  214  which are thicker, that is, have a larger diameter than the wire end portions  212  ( FIG. 7 ). To grip the relatively thick wire end portions  214  ( FIG. 8 ), the plier jaws  104  have to be separated by a distance which is greater than the separation between the plier jaws required to grip the wire end portions  212 . This results in the plier arms or handles  102  and  116  being separated by a relatively large distance ( FIG. 8 ) which is greater than the distance which the plier arms or handles  102  and  116  are separated when the thinner wire end portions  212  ( FIG. 7 ) are gripped. This results in the teeth  218  on the lock pawl  110  engaging teeth  216  on the lock bar  120  at a location which is spaced further from the lower (as viewed in  FIG. 8 ) wire arm or handle  116  than when the relatively wire end portions  212  are gripped ( FIG. 7 ). 
         [0042]    Due to the plier jaws or clamp members  104  being separated by different distances when wire portions  210 ,  212  or  214  ( FIGS. 6 ,  7  and  8 ) having different thickness are gripped, the plier arms or handles  102  and  116  are separated by different distances when wire portions having different thickness are gripped. Due to the different distances between the plier arms or handles  102  and  116  when the wire portions  210 ,  212  or  214  having different thickness are gripped, the lock pawl teeth  218  engage different lock bar teeth  216  when wire portions having different thickness are gripped. This results in the locations where the lock pawl teeth  218  engage the lock bar teeth  216  varying as a function of the thickness of the wire portions being gripped by the plier jaws or clamp members  104 .