FIELD OF THE INVENTION 
       [0001]    This invention relates to a structure of wrench, and more particularly to a wrench that is suitable of being used for various workpieces in multiple specifications, and able to prevent the workpieces from passing through thereof randomly. 
       BACKGROUND OF THE INVENTION 
       [0002]    A conventional structure of wrench, such as U.S. Pat. No. 5,983,758, as shown in  FIG. 61 , has a handle  71  extending out integrally from one side of an annular driving head  70  that is internally equipped with twelve equidistant and continuous V-shaped grooves  72  with the same shape, six of the twelve equidistant V-shaped grooves  72  have each a stop part  73  on one end such that the six grooves  72  are not through. When the driving head  70  is engaged with a workpiece, top of a workpiece would be limited by the stop part  73  and then efficacy of preventing the workpiece taking off randomly from the wrench would be achieved. However, the conventional wrench aforementioned has the shortcoming as follows. 
         [0003]    General workpieces have various shapes, such as gear-shaped, E-shaped, triangle, quadrangle, hexagon, etc. The conventional driving head  70  aforementioned has twelve V-shaped grooves  72 , which can only fit a hexagonal or dodecagonal workpiece. Therefore, the conventional driving head  70  is suitable for limited various workpieces so as to cause a shortcoming of inconvenience in use. 
       SUMMARY OF THE INVENTION 
       [0004]    The main objective of the present invention is to provide a wrench that is suitable of being used for various workpieces, and for preventing the workpieces from passing through the driving head of the wrench randomly. The structure of the wrench is that a plurality of forefront surfaces and grooves are disposed around the internal periphery of the opening of the driving head in an interlaced order, and the forefront surfaces each has a concavity disposed on the middle portion of the protruded curved surface thereof. The concavities have different shapes from grooves and both are to be used to accommodate a workpiece together. Besides, projected stop parts are provided on inside of the opening, with which the objectives of being suitable for various workpieces in multiple specifications and preventing workpieces from passing through the wrench randomly would be achieved. 
         [0005]    The present invention will become more obvious from the following description when taken in connection with the accompanying drawings that show, for purposes of illustration only, a preferred embodiment in accordance with the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a perspective view of the wrench of the present invention; 
           [0007]      FIG. 2  is a top view of the wrench of the present invention; 
           [0008]      FIG. 3  is a partial enlarged view of the wrench of the present invention; 
           [0009]      FIG. 4  is a perspective view of rotating a hexagonal workpiece of the present invention; 
           [0010]      FIG. 5  is a top view of rotating a hexagonal workpiece of the present invention; 
           [0011]      FIG. 6  is a partial enlarged view of rotating a hexagonal workpiece of the present invention; 
           [0012]      FIG. 7  is a perspective view of rotating a hexagonal workpiece of the present invention; 
           [0013]      FIG. 8  is a top view of rotating a hexagonal workpiece of the present invention; 
           [0014]      FIG. 9  is a partial enlarged view of rotating a hexagonal workpiece of the present invention; 
           [0015]      FIG. 10  is a perspective view of rotating an E-shaped workpiece of the present invention; 
           [0016]      FIG. 11  is a top view of rotating an E-shaped workpiece of the present invention; 
           [0017]      FIG. 12  is a perspective view of rotating a gear-shaped workpiece of the present invention; 
           [0018]      FIG. 13  is a top view of rotating a gear-shaped workpiece of the present invention; 
           [0019]      FIG. 14  is a perspective view of rotating a triangular workpiece of the present invention; 
           [0020]      FIG. 15  is a top view of rotating a triangular workpiece of the present invention; 
           [0021]      FIG. 16  is a perspective view of the second embodiment of the present invention; 
           [0022]      FIG. 17  is a top view of the second embodiment of the present invention; 
           [0023]      FIG. 18  is a perspective view of the third embodiment of the present invention; 
           [0024]      FIG. 19  is a top view of the third embodiment of the present invention; 
           [0025]      FIG. 20  is a perspective view of the fourth embodiment of the present invention; 
           [0026]      FIG. 21  is a top view of the fourth embodiment of the present invention; 
           [0027]      FIG. 22  is a perspective view of the fifth embodiment of the present invention; 
           [0028]      FIG. 23  is a top view of the fifth embodiment of the present invention; 
           [0029]      FIG. 24  is a perspective view of the sixth embodiment of the present invention; 
           [0030]      FIG. 25  is a top view of the sixth embodiment of the present invention; 
           [0031]      FIG. 26  is a perspective view of the seventh embodiment of the present invention; 
           [0032]      FIG. 27  is a top view of the seventh embodiment of the present invention; 
           [0033]      FIG. 28  is a perspective view of the eighth embodiment of the present invention; 
           [0034]      FIG. 29  is a top view of the eighth embodiment of the present invention; 
           [0035]      FIG. 30  is a perspective view of the ninth embodiment of the present invention; 
           [0036]      FIG. 31  is a top view of the ninth embodiment of the present invention; 
           [0037]      FIG. 32  is a perspective view of the tenth embodiment of the present invention; 
           [0038]      FIG. 33  is a top view of the tenth embodiment of the present invention; 
           [0039]      FIG. 34  is a perspective view of the eleventh embodiment of the present invention; 
           [0040]      FIG. 35  is a top view of the eleventh embodiment of the present invention; 
           [0041]      FIG. 36  is a perspective view of the twelfth embodiment of the present invention; 
           [0042]      FIG. 37  is a top view of the twelfth embodiment of the present invention; 
           [0043]      FIG. 38  is a perspective view of the thirteenth embodiment of the present invention; 
           [0044]      FIG. 39  is a top view of the thirteenth embodiment of the present invention; 
           [0045]      FIG. 40  is a perspective view of the fourteenth embodiment of the present invention; 
           [0046]      FIG. 41  is a top view of the fourteenth embodiment of the present invention; 
           [0047]      FIG. 42  is a perspective view of the fifteenth embodiment of the present invention; 
           [0048]      FIG. 43  is a top view of the fifteenth embodiment of the present invention; 
           [0049]      FIG. 44  is a perspective view of the sixteenth embodiment of the present invention; 
           [0050]      FIG. 45  is a top view of the sixteenth embodiment of the present invention; 
           [0051]      FIG. 46  is a perspective view of the seventeenth embodiment of the present invention; 
           [0052]      FIG. 47  is a top view of the seventeenth embodiment of the present invention; 
           [0053]      FIG. 48  is a perspective view of the eighteenth embodiment of the present invention; 
           [0054]      FIG. 49  is a top view of the eighteenth embodiment of the present invention; 
           [0055]      FIG. 50  is a perspective view of the nineteenth embodiment of the present invention; 
           [0056]      FIG. 51  is a top view of the nineteenth embodiment of the present invention; 
           [0057]      FIG. 52  is a perspective view of the twentieth embodiment of the present invention; 
           [0058]      FIG. 53  is a top view of the twentieth embodiment of the present invention; 
           [0059]      FIG. 54  is a perspective view of the twenty-first embodiment of the present invention; 
           [0060]      FIG. 55  is a top view of the twenty-first embodiment of the present invention; 
           [0061]      FIG. 56  is a partial enlarged view of the twenty-first embodiment of the present invention; 
           [0062]      FIG. 57  is a perspective view of the twenty-second embodiment of the present invention; 
           [0063]      FIG. 58  is a top view of the twenty-second embodiment of the present invention; 
           [0064]      FIG. 59  is a perspective view of the twenty-third embodiment of the present invention; 
           [0065]      FIG. 60  is a top view of the twenty-third embodiment of the present invention; and 
           [0066]      FIG. 61  is a perspective view of the prior art. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0067]    As shown in  FIGS. 1 to 3 , a basic structure of a box-end wrench of the present invention comprises a driving head  10  and a handle  101  extending from one side of the driving head  10  integrally. The driving head  10  is annular and has a first end and a second end in opposite directions, and a central longitudinal axis that extends to connect the first end and the second end. At least one said end of the driving head  10  is equipped with an opening  100  extending along the central longitudinal axis. The opening  100  has a plurality of grooves  12  that are distributed equidistantly around the internal periphery thereof. The extending directions of the grooves  12  are parallel to the central longitudinal axis. A portion connecting each two adjacent said grooves  12  forms a forefront surface  11 . Each forefront surface  11  is equipped with a concavity  13  on the middle thereof. The extending directions of the concavities  13  are parallel to the central longitudinal axis. The concavities  13  and the grooves  12  are able to accommodate the teeth of a gear-shaped workpiece together. Wherein, one said end of the driving head  10  is equipped with at least a stop part  14  projecting toward the central longitudinal axis on the inner of the opening  100 , so that when the workpiece is inserted into the opening  100  from the other said end of the driving head  10 , which can be blocked by the stop part  14 . 
         [0068]    As shown in  FIGS. 1 to 3 , the number of the forefront surfaces  11  and the grooves  12  each are six, which are disposed annularly in an interlaced order. The forefront surfaces  11  may be a curved surface projecting toward the central longitudinal axis. The grooves  12  and the forefront surfaces  11  each are in the form of curved surfaces, and the junction of the two curved surfaces is tangent to each other. The number of the concavity  13  is six and the size of the concavity  13  is big enough to accommodate a tooth  41  of a gear-shaped workpiece  40  (as shown in  FIGS. 12 and 13 ), or a tooth  31  of an E-shaped workpiece  30  with six encircling teeth (as shown in  FIGS. 10 and 11 ). Moreover, in the embodiment of  FIGS. 1 to 3 , the concavity  13  includes two side surfaces  130 ,  131  and a bottom  132 , in which the bottom  132  may be an arc surface or a flat surface. The included angle of the two side surfaces  130 ,  131  may be zero degree (namely parallel), greater or smaller than 90 degree. In the embodiment shown in  FIGS. 1 to 3 , the two side surfaces  130 ,  131  of the concavity  13  are parallel to each other, and the bottom  132  is a flat surface. Moreover, in the embodiment shown in  FIGS. 1 to 3 , the number of the stop part  14  is six and the stop parts  14  may be located on the concavities  13  near the first end of the driving head  10 , which makes the concavities  13  not through. The distal end of the stop part  14  is in the form of a curved surface that is on the same curved surface as the forefront surface  11 , with which the driving head  10  is able to fit on various shapes of workpieces and has the function of preventing the workpieces taking off randomly. 
         [0069]    Referring to  FIGS. 4 to 6 , when the driving head  10  of the present invention accommodates a workpiece  20  with an angle, the forefront surfaces  11  of the driving head  10  are engaged with the six edges of the workpiece  20 , which is the same as the conventional operation. 
         [0070]    Referring to  FIGS. 7 to 9 , when the driving head  10  accommodates the workpiece  20  with another angle, the forefront surfaces  11  of the driving head  10  are also engaged with the six edges of the workpiece  20  and the top portions of the workpiece  20  touch the stop parts  14 , so as to prevent the workpiece  20  from passing through the opening  100  of the driving head  10 . 
         [0071]    As shown in  FIGS. 10 and 11 , when the driving head  10  accommodates an E-shaped workpiece  30  with six teeth  31 , the teeth  31  are accommodated within the concavities  13  and the top portions of the teeth  31  touch the stop parts  14 , thus to prevent the E-shaped workpiece  30  from passing through the opening  100  of the driving head  10 . In the embodiment of these two figures, the stop parts  14  are located on the concavities  13  near the first end of the driving head  10 . 
         [0072]    As shown in  FIGS. 12 and 13 , when the driving head  10  accommodates a gear-shaped workpiece  40  with twelve teeth  41 , the teeth  41  are accommodated within the concavities  13  and the top portions of the teeth  41  touch the stop parts  14 , thus to prevent the gear-shaped workpiece  40  from passing through the opening  100  of the driving head  10 . 
         [0073]    Referring to  FIGS. 14 and 15 , when the driving head  10  accommodates a triangular workpiece  60 , corners  61  of the triangular workpiece  60  are accommodated within the concavities  13  and restricted by the stop parts  14 , thus to prevent the triangular workpiece  60  from passing through the opening  100  of the driving head  10 . 
         [0074]    In the embodiment shown in  FIGS. 16 and 17 , the number of the stop part  14  is three, which are located on three equidistant said concavities  13  respectively. 
         [0075]    In the embodiment shown in  FIGS. 18 and 19 , the number of the stop part  14  is one, which is located on one said concavity  13 . 
         [0076]    In the embodiment shown in  FIGS. 20 and 21 , the number of the stop part  14  is twelve, which are located on the grooves  12  and the concavities  13  one by one and are all located on the first end of the driving head  10 . These stop parts  14  connect with each other to form a dodecagonal inner circumference for accommodating another workpiece. 
         [0077]    In the embodiment shown in  FIGS. 22 and 23 , the number of the stop part  14  is six, three of the stop parts  14  are located on the opening  100  near the first end of the driving head  10  and other three are located on the opening  100  near the second end of the driving head  10 . The preferred embodiment of  FIGS. 22 and 23  shows that three of the stop parts  14  are located equidistantly on the concavities  13  near the first end of the driving head  10  and other three are located equidistantly on the concavities  13  near the second end of the driving head  10 . 
         [0078]    In the embodiment shown in  FIGS. 24 and 25 , the ends of the stop parts  14  are formed as flat surfaces. 
         [0079]    In the embodiment shown in  FIGS. 26 and 27 , the ends of the stop parts  14  are formed as concave curved surfaces, the forefront surfaces  11  are convex curved surface, the junctions of the curved surfaces of the stop parts  14  and the curved surfaces of the forefront surfaces  11  are round corners. Furthermore, the ends of the stop parts  14  are formed as concave curved surfaces, and the shapes of the concave curved surfaces of the stop parts  14  can be the same as the groove  12 . 
         [0080]    In the embodiment shown in  FIGS. 28 and 29 , the ends of the stop parts  14  are formed as concave curved surfaces and the junctions of the curved surfaces of the stop parts  14  and the forefront surfaces  11  are round corners. The curved surfaces of the stop parts  14  are paraboloid and the junctions of the paraboloid and the concavities  13  are round corners. 
         [0081]    In the embodiment shown in  FIGS. 30 and 31 , the stop parts  14  have indentations  140  that have similar shapes with the concavities  13  and are deflected toward the central longitudinal axis of the driving head  10 . 
         [0082]    In the embodiment shown in  FIGS. 32 and 33 , the number of the stop part  14  is twelve, which are located on the grooves  12  and the concavities  13  one by one and are all located on the first end of the driving head  10 . These stop parts  14  connect with each other to form a hexagonal inner circumference for accommodating another workpiece  20 . If the forefront surfaces  11  of the driving head  10  can rotate a 19 mm workpiece, the inner circumference of the stop parts  14  can rotate an 18 mm workpiece. 
         [0083]    In the embodiment shown in  FIGS. 34 and 35 , the number of the stop part  14  is twelve, which are located on the grooves  12  and the concavities  13  one by one and are all located on the first end of the driving head  10 . The inner circumference formed by the connection of these stop parts  14  includes twelve V-shaped indentations  141  that have the same shapes and are spaced equidistantly for driving a smaller size of workpiece. 
         [0084]    In the embodiment shown in  FIGS. 36 and 37 , the number of the stop part  14  is twelve, which are located on the grooves  12  and the concavities  13  one by one and are all located on the first end of the driving head  10 . The inner circumference formed by the connection of these stop parts  14  includes twelve V-shaped indentations  142  that have the same shapes and are spaced equidistantly for driving a workpiece with same size. 
         [0085]    In the embodiment shown in  FIGS. 38 and 39 , the number of the stop part  14  is twelve, which are located on the grooves  12  and the concavities  13  one by one and are all located on the first end of the driving head  10 . The inner circumference formed by the connection of these stop parts  14  includes twelve round arc indentations  143  that have the same shapes and are spaced equidistantly. 
         [0086]    In the embodiment shown in  FIGS. 40 and 41 , the number of the forefront surface  11 , the groove  12  and the concavity  13  each are six. The number of the stop part  14  is twelve, which are all located on the first end of the driving head  10 . The shape of the inner circumference formed by the connection of these stop parts  14  is the same as the inner shape of the second end of the driving head  10 . 
         [0087]    In the embodiment shown in  FIGS. 42 and 43 , the number of the stop part  14  is twelve, which are all located on the first end of the driving head  10 . The number of the forefront surface  11 , the groove  12  and the concavity  13  each are six. The inner circumference formed by the connection of these stop parts  14  includes six equidistant first indentations  144 . The shape of each said first indentations  144  is similar to the shape of the groove  12 , which has the function of rotating dual size of workpieces. 
         [0088]    In the embodiment shown in  FIGS. 44 and 45 , the number of the stop part  14  is twelve, which are located on the grooves  12  and the concavities  13  one by one and are all located on the first end of the driving head  10 . The inner circumference formed by the connection of these stop parts  14  includes twelve equidistant V-shaped second indentations  145 . 
         [0089]    In the embodiment shown in  FIGS. 46 and 47 , the number of the stop part  14  is twelve, which are located on the grooves  12  and the concavities  13  one by one and are all located on the first end of the driving head  10 . The inner circumference formed by the connection of these stop parts  14  includes twelve equidistant V-shaped third indentations  146 . The partial portions of the forefront surfaces  11  are more prominent than the third indentations  146 . 
         [0090]    In the embodiment shown in  FIGS. 48 and 49 , the stop parts  14  are located on the grooves  12 , namely the grooves  12  are not through. The ends of the stop parts  14  are in the form of curved surfaces and the junctions of the curved surfaces of the stop parts  14  and the curved surfaces of the forefront surfaces  11  are round corners. 
         [0091]    In the embodiment shown in  FIGS. 50 and 51 , the stop parts  14  are located on the grooves  12 . In the embodiment shown in  FIGS. 50 and 51 , the ends of the stop parts  14  may have fourth indentations  147  that have the same shapes as the concavities  13 . 
         [0092]    In the embodiment shown in  FIGS. 52 and 53 , the stop parts  14  are located on the forefront surfaces  11 . 
         [0093]    In the embodiment shown in  FIGS. 54 to 56 , the concavities  13  are round arc surfaces and the stop parts  14  are located on the concavities  13 . 
         [0094]    In the embodiment shown in  FIGS. 57 and 58 , the number of the forefront surface  11 , the groove  12  and the concavity  13  each are six. Each said concavity  13  is a round arc surface. The number of the stop part  14  is twelve, which are all located on the first end of the driving head  10 . The shape of the inner circumference formed by the connection of these stop parts  14  is similar to the inner shape of the opening  100  on the second end of the driving head  10 . 
         [0095]    In the embodiment shown in  FIGS. 59 and 60 , the number of the forefront surface  11 , the groove  12  and the concavity  13  each are six, each said concavity  13  is a round arc surface. The number of the stop part  14  is twelve, which are all located on the first end of the driving head  10 . The inner circumference formed by the connection of the stop parts  14  includes six equidistant fifth indentations  148  and six equidistant sixth indentations  149 . The shape of each said fifth indentation  148  is similar to the shape of the groove  12 , and each said sixth indentations  149  includes two parallel sides  150 . 
         [0096]    Another embodiment of the present invention, the forefront surface of the driving head includes at least two protruded curved surfaces, which is not shown with a figure. The present invention may also have the driving head be equipped with a gap on one side, which is also not shown with a figure. 
         [0097]    While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.
The present invention relates to a structure of wrench, which is mainly that a handle extends out from one side of a driving head integrally, a plurality of forefront surfaces and grooves are disposed around the internal periphery of the opening of the driving head in an interlaced order, and the forefront surfaces each has a concavity disposed on the middle portion of the protruded curved surface thereof. The concavities have different shapes from grooves and both are to be used to accommodate a workpiece. Besides, projected stop parts are provided on inside of the opening, with which the objectives of being suitable for various workpieces in multiple specifications and preventing the workpieces from passing through the driving head randomly would be achieved.