Abstract:
A combination wrench with adjustable heads is provided. The wrench includes a handle and a open head and box head respectively pivoted to two ends of the handle. The open head is combined with a first and a second clamping jaws in shear arrangement. The box head is combined with a first and a second web pivoted together at their distal portions. When rotate the handle counterclockwise, both the open head and the box head can be able to firmly comp a wording object and then to fasten or unfasten the object. The handle can make back runs when it rotates clockwise.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to carpentry tools and more particularly to a combination wrench with adjustable heads which can be automatically adjusted to consist with the size of an object such as a nut to which it rotates. 
     People usually use different sizes of combination wrenches to work at different sized nut which is uneconomical. A typical adjustable combination wrench (as shown in FIG. 1) is thus worked out which comprises a handle  1  and a pair of rotatable boxes  3  of irregular hexgon pivoted at two ends of the handle  1 . The handle  1  has a jaw  2  at each ends. When engages the box  3  with a working object such as a hexgon nut and rotates the handle  1 , the jaw  2  presses a side of the object to reduce the size of the box  3  in order to fit the shape of the object and further to faster or unfasten the object. This type of combination wrench provides a limited range to fit some of the hexgon nuts. However, it has the advantages set forth as follows: 
     a) because of a greater wondering clearance, it causes a free run which damages or deforms the working object, 
     b) the repeated engagement and/or disengagement with the object requires a rotation angle that greater the 60° which causes an operation limitation to the user, and 
     c) it does not fit a small working object or operate within a small space. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention has a main object to provide a combination wrench with adjustable heads which heads can automatically stretched open to fit a working object. 
     Another object of the present invention is to provide a combination wrench with adjustable heads which can firmly engage the working object during rotation and the handle can be back run. 
     Accordingly, the combination wrench of the present invention comprises generally a handle, an open end pivoted to one end and box head pivoted to the other end of the handle. The heads each has a first and a second jaw pivoted together in a shear arrangement and biased at their inner ends with a spring means to force the jaws to stretch open. The jaws each has serration on inner surface and a stop block against a side of the handle. So that the jaws are usually stretched open to fit the size of a working object and firmly engage with the object when the handle rotates. Further the handle enables to back run during fastening or unfastening the working object. 
     The present invention will become more fully understood by reference to the following detailed description thereof when read in conjunction with the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is plane view of a combination wrench according to a prior art, 
     FIG. 2 is an exploded perspective view to show a combination wrench of a preferred embodiment according to the present invention, 
     FIG. 3 is a sectional view of an assembled combination wrench of FIG. 2 while the heads are stretched open, 
     FIG. 4 is a sectional view of an assembled combination wrench of FIG. 2 while the heads are closed. 
     FIG. 5 is a perspective view to show an assembled combination wrench of the preferred embodiment, and 
     FIG. 6 is a sectional view to show an alternative embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to FIGS. 2 and 3 of the drawings, the combination wrench of the present invention comprises generally a rectangular handle  10 , an adjustable open head pivoted to one end an adjustable box head pivoted to the other end of the handle  10  and a roughly U-shaped spring means. 
     The handle  10  has two round ends each including an opening  11  and  12  to define a lug, an aligned thru hole  111  and  121  in the lug for engaging with a rivet pin  112  and  122  and a pair of retaining edges  113  and  114 ,  123  and  124 . 
     The open head is combined with a first and second jaw members  13  and  14 . The first jaw member  13  has a first clamping jaw  131  including serrations  132  on inner side to define a plurality of bevel surfaces  133  therebetween, a first thru hole  134  abutting an extension  135  on an inner side of the jaw member, a first notch  136  in the other side opposite to the thru hole  134  and a first leg member  137  extending longitudinally from the thru hole  134  including a first lateral recess  1371  in a middle portion of the leg  137 . The first thru hole  134  is engageable with the aligned thru hole  111 . 
     The second jaw member  14  has a second clamping jaw  141  including serrations  142  on inner side to define a plurality of bevel surfaces  143  therebetween, a second thru hole  144  in a middle portion of the jaw member  14 , a second notch  146  in an inner side of the jaw  14 , a second leg  147  extending longitudinally from the thru hole  144  including a second lateral recess  1471  in a middle portion and a right angled portion  145  defined between the leg  147  and the jaw member  14 . 
     The roughly U-shaped spring means  21  includes a pair of transverse ends  211  and  212  respectively engageable into the first and second lateral recesses  1371  and  1471  of the legs  137  and  147 . 
     When assembling, put the second jaw member  14  on the first jaw member  13  and make alignment of the thru holes  134  with the thru hole  144  and engage the transverse portions  211  and  212  of the spring means  21  into the lateral recesses  1371  and  1471  respectively, then engage the legs  137  and  147  into the opening  11  of the handle and pivot the first and second clamping jaws  13  and  14  to the handle as the thru holes  134 ,  144  and  111  are aligned with each other (as shown in FIG.  3 ). 
     The box head is combined with a first and a second web member  15  and  16  and a roughly OC-shaped spring means  22 . 
     The first web member  15  has a roughly U-shaped clamping jaw  151  including serrations  152  on inner side to define a plurality of bevel surfaces  153  therebetween, a semi-circular slot  154  in an inner side, a third thru hole  155  in a reduced distal of the clamping jaw  151 , a third notch  156  positioned remote to the semi-circular slot  154  and a third leg  157  extending longitudinally from the slot  154  including a first vertical recess  1571  in a distal portion of the leg  157 . 
     The second web member  16  has an arcuate clamping jaw  161  including serrations  162  on inner side to define a plurality of bevel suitcase  163  therebetween, a fourth thru hole  165  in a reduced distal of the clamping jaw  161  engageable with the third thru hole  155  of the first web member  15  and pivoted by a small rivet  168 , a concave  166  in an inner side, a fourth leg  167  extending longitudinally from the concave  166  including a second vertical recess  1671  in a distal portion, a third thru hole  168  engageable with the semi-circular slot  154  and the first thru hole  121  and a right angled portion  164  defined between the fourth leg  167  and the second web member  16 . 
     The roughly OC-shaped spring means  22  has a pair of vertical ends  221  and  222  respectively engageeable with the first and second vertical recesses  1571  and  1671  of the first and second web members  15  and  16 . The vertical ends  1571  and  1671  are directionally toward each other. 
     When assembling, rotate the second web member  16  to overlap with first web member  15  until their legs  157  and  167  engaged with each other, then respectively engage the vertical ends  221  and  222  of the spring means  22  into the first and second vertical recesses  1571  and  1671  from the opposite side of the legs  157  and  167 , and then insert the combined web members  15  and  16  into the opening  12  of the handle  10  and align the third thru hole  168  with the first thru hole  121  and finally, pivot the box head to the handle  10  by rivet  122  (as shown in FIG.  3 ). 
     FIG. 5 shows an outlook of the assembled combination wrench of the present invention. 
     Referring to FIG.  4  and FIG. 3 again, both the open head and the box head are usually remaining in a stretch open position, however, the first notch  136  of the first clamping jaw  13  and the right angled portion  145  of the second clamping jaw  14  are retained respectively by the retaining edges  113  and  114 , and the right angled portion of the second web member is retained by the retaining edge  124 . 
     In operation, if use the open head, engage the clamping jaws  14  onto a working object such as a hexgon bolt  30  and rotate the handle  10  counterclockwise, the retaining edge  113  moves forward first stopping against the second notch  146  and then narrowing the space between clamping jaws  13  and  14  so as to firmly clamp to bolt  30  wherein the edges of the bolt  30  engage with the bevel surfaces  133  and  143  (as shown in FIG.  4 ). Further rotation of the handle  10  counterclockwise is to fasten or unfasten the bolt  30 , slight rotation of the handle  10  clockwise can make back run of the open head because of the tension of the spring means  21  and the bevel surfaces of the clamping jaws  13  and  14 . 
     If use the box head, engage the box head onto a hexgon bolt  31 , then rotate the handle  10  counterclockwise also that the retaining edge  123  engage into both the concave  166  of the second web member  16  and the third notch  156  of the first web member  15  so as to firmly clamp the bolt  31 . Further rotation of the handle  10  counterclockwise, one can fasten or unfasten the bolt  31 . The box head can also make back run as decried the above for the open head. 
     Referring FIG. 6, and alternative embodiment of the combination wrench of the present invention is provided. This embodiment comprises a hollow interior handle  40  having opening in each of the first and second ends and a thru hole abutting each of the first and second ends, an open head and a box head. 
     The open head includes a fixed jaw  51  and movable jaw  52  of serrated inner side. The fixed jaw  51  has a circular thru hole  55  engageable with the thru hole at the first end of the handle  40  and secured by rivet  58  and a rectangular hole  53  into which a spring  57  is rotatably secured. The movable jaw has an oblong hole  56  slidably engaged with the rivet  58  and a threaded rectangular hole  54  engaged with the spring  57 . So that the movable jaw  52  can slide in or out relative to the fixed jaw  51  to readily clamp a working object which is to be fastened or unfastened. 
     The box head has a fixed web  51  and a movable web  52  pivoted at their forward ends by a small rivet and both of them having inner serrations. The fixed web has a circular thru hole  65  engageable with thru hole at the second end of the handle  40  and secured by rivet  68  and a rectangular hole  53  into which a spring  67  is rotatably secured. The movable web  62  has an oblong hole  66  slidably engaged with the rivet  68  and a threaded rectangular hole  64  engaged with the spring  67 . So that the movable jaw  62  can slide in or out relative to the fixed jaw  61  to clamp a working object which is to be fastened or unfastened. 
     The specification relating to the above embodiments should be construed as exemplary rather than as limitative of the present invention, with many variations and modifications being readily attainable to a person of average skill in the art without departing from the spirit or scope thereof as defined by the appended claims and their legal equivalents.