Abstract:
An adjustable wrench for gripping hexagonal and other shaped heads includes two slightly non-parallel jaw faces, wherein one face is smoother than the other. The angle between the two jaw faces is extremely shallow to create a “snap-action” geometry. Combining that geometry with jaw faces of unequal roughness can result in a desirable binding action that causes the wrench to tightly grip the head. In some cases, the wrench will continue clinging to the head even after the user releases the handle of the wrench.

Description:
FIELD OF THE INVENTION 
       [0001]    The subject invention generally pertains to adjustable spanner wrenches and more specifically to the jaws of such a wrench. 
       BACKGROUND OF RELATED ART 
       [0002]    Adjustable spanner wrenches are typically used for tightening hexagonal nut and bolt heads. Although the span between the parallel jaw faces is adjustable to fit hexagonal and square heads of various sizes, some clearance between the head and the jaw is often needed in order to slide the wrench onto the head. Such clearance, however, can cause the wrench to accidentally slip off the head. If a bolt or nut is particularly tight, the wrench might round the corners of the head, which can make the head even more difficult to grip. Consequently, there is a need for a better adjustable wrench. 
       SUMMARY OF THE INVENTION 
       [0003]    It is an object of the present invention to provide an adjustable wrench with slightly non-parallel jaw faces for tightly gripping opposite parallel faces of a hexagonal head. 
         [0004]    Another object of some embodiments is to provide a tightly gripping adjustable wrench that does not rely on one jaw having to pivot relative to another. 
         [0005]    Another object of some embodiments is to provide an adjustable wrench with a single set of jaws that can grip hexagonal, square, round, and pentagonal heads. 
         [0006]    Another object of some embodiments is to provide a wrench that tightens its grip on a head by way of rotating the entire wrench as a unit (i.e., one wrench component does not have to move relative to another wrench component). In some cases, the resulting grip becomes so tight that even after the user releases the wrench&#39;s handle, the wrench continues to hang onto the head all by itself. 
         [0007]    Another object of some embodiments is to provide an adjustable wrench that can engage a hexagonal head by inserting the head into the wrench&#39;s jaws in a direction nearly inline with the longitudinal axis of the wrench&#39;s handle. In other words, the angle between the handle and the direction in which the adjustable jaw moves is twenty to ninety degrees. 
         [0008]    Another object of some embodiments is to provide a set of jaws with jaw faces that are generally planar, although one jaw face may be roughened with a series of teeth. 
         [0009]    Another object of some embodiments is to provide an adjustable wrench with a set of jaws wherein one jaw face is smoother than the other. 
         [0010]    Another object of some embodiments is to provide a wrench with diverging jaw faces that provide a settling-in ratio of 0.25 to 0.26 with respect to a perfect hexagon, thereby providing a tight fitting grip with an actual hexagonal head. 
         [0011]    Another object of some embodiments is to provide a jaw design (slightly diverging jaw faces with one face rougher than the other) that can be applied to wrenches with either an adjustable jaw opening (e.g., adjustable spanner) or a fixed jaw opening (e.g., open-end wrench). 
         [0012]    Another object of some embodiments is to provide an adjustable wrench with diverging jaws that define a vertex that extends beyond the length of the wrench&#39;s handle when the wrench is fully open, or extends at least half the wrench&#39;s overall length. 
         [0013]    Another object of some embodiments is to provide wrench with just one relatively smooth jaw face having a surface roughness of less than 125 microinches. 
         [0014]    Another object of some embodiments is to roughen the surface of a jaw by depositing a carbide-alloy coating (e.g., tungsten carbide) on the jaw&#39;s face. 
         [0015]    Another object of some embodiments is to provide a wrench with a theoretical snap-in feature that in some real situations translates to a tight gripping/binding action on various shaped heads. 
         [0016]    One or more of these and/or other objects of the invention are provided by a wrench with two jaw faces that diverge at a certain unique angle, wherein one jaw face is rougher than the other to create a certain settling-in ratio, a certain snap-in feature, and/or a certain binding action for firmly gripping heads of various shapes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0017]      FIG. 1  is a front view of a wrench shown in relation to a hexagon (mathematical model). 
           [0018]      FIG. 2  is an enlarged front view of  FIG. 1  illustrating a state of equilibrium (second state of equilibrium). 
           [0019]      FIG. 3  is an enlarged front of  FIG. 2  but illustrating another state of equilibrium (first state of equilibrium). 
           [0020]      FIG. 4  is an enlarged front view of  FIG. 2 . 
           [0021]      FIG. 5  is a front view similar to  FIGS. 3 and 4  but illustrating an intermediate state. 
           [0022]      FIG. 6  is a front view showing a comparison of  FIGS. 3-5 . 
           [0023]      FIG. 7  is a front view similar to  FIG. 4  but showing an alternate jaw face. 
           [0024]      FIG. 8  is a front view similar to  FIG. 7  but showing yet another alternate jaw face. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]      FIGS. 1-6  show an adjustable wrench  10  adapted to grip a polygonal head including, but not limited to, a hexagonal head. Wrench  10  comprises a handle  12  defining a longitudinal axis  14 , a first jaw  16  connected to handle  14  and having a first jaw face  18  that defines a first plane  20 , and a second jaw  22  connected to handle  12  and having a second jaw face  24  that defines a second plane  26 . In the case where handle  12  happens to be curved, longitudinal axis  14  is defined as the best fitting linear neutral axis of the curved shape. The expression of a jaw being connected to a handle means that the two are in some way coupled to each other or one is an integral extension of the other. 
         [0026]    Jaws  16  and  22  are movable in substantially linear translation relative to each other so that wrench  10  can be moved in an adjustment direction  28  to receive heads of various sizes and shapes (e.g., hexagonal, pentagonal, square, round, irregular, etc.). Due to the wrench&#39;s ability to grip a variety of shapes, wrench  10  preferably includes only one set of jaws  16  and  22 . For the illustrated example, first jaw  16  is fixed relative to handle  12 , and second jaw  22  is adjustably movable relative to jaw  16  and handle  12 ; however, it is well within the scope of the invention to have either jaw  16  or  22  be the one that is movable relative to handle  12 . 
         [0027]    The adjustable jaw, such as jaw  22 , could be moved by any one of a variety of known drive mechanisms including, but not limited to, manually sliding jaw  22  directly. For illustration, jaw  22  is shown being moved by a toothed gear rack  30  that meshes with a manually or otherwise rotatable worm gear  32 . Rack  30  rigidly extends from jaw  22  and slides along a channel  34  in wrench  10 . Depending on which direction worm gear  32  is rotated, rack  30  and jaw  22  move in or out to respectively close or open wrench  10 . 
         [0028]    Jaws  16  and  22  have a special geometry that provides wrench  10  with some unique benefits. One, the jaw&#39;s geometry can eliminate the clearance or play that typically exists during fit-up between a standard wrench and a hexagonal head just prior to rotating the wrench. And, two, the geometry can provide a tactile “snap-in” feel as wrench  10  settles into driving engagement with a hexagonal head. The geometry is also useful for gripping round or irregular shapes such as a worn hexagonal head with rounded corners. 
         [0029]    To achieve such benefits, jaw faces  18  and  24  diverge at a slight jaw angle  36 , and one jaw face is smoother than the other, e.g., jaw face  24  is smoother than jaw face  18 . Angle  36  is measured with reference to planes  20  and  26 . Planes  20  and  26  are defined as planes that lie along their respective jaw faces  18  and  24 . In the case where a jaw face includes a plurality of teeth  38  (e.g., jaw  16 ), its associated plane (e.g., plane  20 ) would lie along the peaks of teeth  38 . Angle  36  should be greater than zero degrees and preferably less than 15 degrees for satisfactory results. More solid engagement and less slippage with a hexagonal head are achieved when angle  36  is between 2 and 8 degrees. The 8-degree angle limit is approximately the angle created by two lines  40  and  42  of  FIG. 4 , wherein line  40  passes through two engagement points  44  and  46  of a hexagon  50 , and line  42  passes through point  44  and an approximate midpoint  48  of one side of hexagon  50 . If angle  36  becomes too close to zero degrees (e.g., one degree), jaws  16  and  22  tend to bind excessively to a round head. Angle  36  being about 4 degrees (plus or minus one degree) appears to be the currently preferred optimum. 
         [0030]    Due to jaw angle  36 , planes  20  and  26  intersect at a vertex  52 . Angle  36  and the jaw adjustment of wrench  10  preferably place vertex  52  at a great distance from jaws  16  and  22  when the jaws are fully open (i.e., at their maximum open position). Specifically, when the jaws are fully open, a distance  54  from vertex  52  to a distal tip  56  of jaw  22  is preferably greater than an overall length  58  of wrench  10  or at least greater than half of length  58 . Such a geometry provides an enhanced gripping function with respect to the workpiece and minimizes the manual pressure it take to force the wrench into a self-gripping relationship with the workpiece. 
         [0031]    The ability of wrench  10  to effectively grip a workpiece is due in part to one jaw being rougher than the other. Making jaw face  18  rougher than jaw face  24 , or vice versa, can be achieve in various ways including, but not limited to, teeth  38 , knurling, random irregularities, high-friction or rough coatings, and various combinations thereof.  FIG. 7 , for example, shows a wrench  10 ′ with a relatively rough jaw face  18 ′ having a plurality of teeth  38 ′ plus a rough coating  60 .  FIG. 8  shows a wrench  10 ″ with just a rough coating  62  (e.g., 0.002″ thick). Coatings  60  and  62  can be a carbide alloy such as tungsten carbide deposited using a model 55 applicator gun and a 8211 tungsten carbide electrode provided by Rocklin Manufacturing Company of Sioux City, Iowa. Other coatings are certainly conceivable and well within the scope of the invention. 
         [0032]    Although the shape, size and number of teeth  38  may vary, in a currently preferred embodiment, teeth  38  have about a 90-degree apex (peak angle) and are distributed at about a pitch distance  64  of 0.050″ increments ( FIG. 6 ). Teeth  38  preferably lean about 20-degrees inward toward vertex  52 . 
         [0033]    The smoother jaw face, e.g., jaw face  24 , preferably has an Ra value (roughness average value) of less than 125 microinches. Thus, the rougher jaw face, e.g., jaw face  18 , should have an Ra value appreciably greater than that. 
         [0034]    The operation of wrench  10  will be described with reference to hexagon  50  and planes  20  and  26 . Hexagon  50  and planes  20  and  26  are mathematical representations and not necessarily physically real. 
         [0035]      FIG. 3  shows the wrench&#39;s initial engagement with hexagon  50 , wherein wrench  10  is in a first state of equilibrium. In this state, a first side  50   a  of hexagon  50  touches and lies along first plane  20 , and an opposite side  50   b  of hexagon  50  touches second plane  26  yet is displaced out of parallel alignment with second plane  26 . The angle of displacement is generally equal to jaw angle  36 . The term, “side” of a hexagon includes the side&#39;s corner end points. The terms, “first side” and “opposite side” simply means that the two sides are substantially parallel and at opposite sides of the hexagon. 
         [0036]    It is in  FIG. 4  that hexagon  50  is defined in relation to wrench  10  being at some given open position, wherein the given open position can be, but is not necessarily, at the wrench&#39;s fully open position (maximum open position). Specifically, first jaw face  18  and second jaw face  24  define hexagon  50  at a first position as follows: first side  50   a  of hexagon  50  touches first plane  20  (e.g., point  44 ) and lies at jaw angle  36  relative first plane  20 , and opposite side  50   b  of hexagon  50  lies against and substantially parallel to second jaw face  24  and terminates at distal tip  56  of second jaw face  24 , wherein distal tip  24  is the point on second jaw face  24  (and on second plane  26 ) that is farthest away from vertex  52 . 
         [0037]      FIG. 4  shows wrench  10  in a second state of equilibrium. This second state of equilibrium can be reached by manually rotating wrench  10  in direction  64  ( FIG. 3 ) relative to hexagon  50 , whereby wrench  10  moves from its position of  FIG. 3  to that of  FIG. 4 . In the second state of equilibrium, first side  50   a  of hexagon  50  touches first plane  20  (point  44 ) yet is displaced out of parallel alignment with first plane  20 , and opposite side  50   b  of hexagon  50  touches and lies along second plane  26 . The angular displacement of first side  50   a  and first plane  20  is generally equal to jaw angle  36 . 
         [0038]    Upon wrench  10  rotating from its first state of equilibrium of  FIG. 3  to its second state of equilibrium of  FIG. 4 , wrench  10  passes through an intermediate state shown in  FIG. 5 . In the intermediate state, first side  50   a  of hexagon  50  touches first plane  20  yet is displaced out of parallel alignment with first plane  20 , and opposite side  50   b  of hexagon  50  touches second plane  24  yet is displaced out of parallel alignment with second plane  24 . 
         [0039]    It should be noted that in the intermediate state of  FIG. 5 , hexagon  50  is farther away from vertex  52  than when hexagon  50  was in either of the two equilibrium conditions of  FIGS. 3 and 4 . The difference in spacing between hexagon  50  and vertex  52  as wrench  10  moves to its various states is referred to as a snap-in distance  66 , which is shown in  FIG. 6 . Snap-in distance  66  is measured with reference to the hexagon&#39;s center point moving between a first point  68   a  ( FIGS. 3 and 4 ) to a second point  68   b  ( FIG. 5 ). For smooth operation, snap-in distance  66  preferably is greater than half of pitch distance  64 , and/or a settling-in ratio of snap-in distance  66  to a slide distance  70  is preferably greater than 0.250 and less than 0.260. Slide distance  70  is defined as the displaced distance of point  46  along a jaw face as hexagon  50  moves from the first state of equilibrium ( FIG. 3 ) to the second state of equilibrium ( FIG. 4 ). Slide distance  70 , snap-in distance  66 , and the settling-in ratio are defined and calculated with reference to ideal mathematical models, i.e., perfect hexagon, perfect jaw planes, and with no part deformation or strain. 
         [0040]    Although snap-in distance  66  may or may not always provide a user with an actual tactile sensation that indicates that wrench  10  has moved from its point of initial contact ( FIG. 3 ) to a point of firm engagement ( FIG. 4 ), an additional benefit is that a real hexagonal bolt head tends to bind more tightly between jaws  16  and  22  as wrench  10  begins rotating in direction  64  from its position of  FIG. 3 . This binding action is due to jaw face  18  being rougher than jaw face  24 . So, instead of an actual hexagonal head moving through the theoretical or mathematical positions of  FIGS. 3-5 , point  44  on hexagon  50  tends to “stick” or grip jaw face  18  while engagement point  46  on hexagon  50  tends to slide on jaw face  24 . Regardless of the movement following an ideal mathematically defined path (i.e.,  FIGS. 3-6 ) or an actual path (with binding, strain and/or material deformation), hexagon  50  can maintain continuous contact with both jaw faces  18  and  24 , thus avoiding the usual clearance play often experienced with conventional wrenches. 
         [0041]    In some cases, to initiate the wrench&#39;s binding or gripping action, particularly in the case where the gripped head is rounded and relatively hard, some manual force may be needed to push wrench  10  onto the head. Exerting such manual force tends to be easier if handle  12  is pointing generally in the same direction as the force that pushes wrench  10  onto the head; otherwise, handle  12  could present a rotational moment with a lever arm that works against the user. To minimize this concern, adjustment direction  28  is at an adjustment angle  72  ( FIG. 2 ) relative to longitudinal axis  14  of handle  12 , wherein adjustment angle  72  is preferably 20 to 90 degrees. 
         [0042]    It should be noted that all drawing figures, specified angles, and descriptions are with respect to jaws  16  and  22  being biased apart from each other (spread apart) to eliminate any backlash or incidental moving part clearances. 
         [0043]    Although the invention is described with respect to a preferred embodiment, modifications thereto will be apparent to those of ordinary skill in the art. The scope of the invention, therefore, is to be determined by reference to the following claims: