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CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority benefit of U.S. Provisional Patent Application No. 60/977,676, filed Oct. 5, 2007, the disclosure of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to adjustable trowels, and more specifically to adjustable trowels used for applying and smoothing material on drywall or similar materials and having hinged plates for adjusting to a variety of angles. 
       BACKGROUND OF THE INVENTION 
       [0003]    Various hand tools exist for applying, smoothing and leathering out joint compound during the construction of building spaces using so called dry wall or gypsum board panels. Where the joint to be finished is between two panels lying in the same plane, a planar trowel is commonly used. The planar trowel generally comprises a single thin steel rectangular sheet having a handle affixed thereto. Alternatively, a relatively wide putty knife may be used. Where two sheets of dry wall meet at a right angle, there is also available a trowel comprising a single thin sheet metal member that is bent along a midline to define two planar surfaces meeting at a fixed 90 degree angle. Again, a handle is affixed to the sheet metal member to facilitate positioning of the trowel in a corner joint and drawing it along the joint as joint compound is applied. 
         [0004]    In many instances, dry wall panels are not oriented only at 180 degrees and at 90 degrees relative to one another, making it necessary for a tradesman to carry several trowels for accommodating a wide variety of angles. What is needed is an improved design for an adjustable hinged corner trowel. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention meets the above-described need by providing an adjustable hinged corner trowel formed from hinged plates with a removeably attached handle. Cooperating control arms connect the handle to the hinged plates. The cooperating arms are preferably constructed of wire and may have teeth and grooves capable of engagement for adjusting and locking the hinged plates into various positions. 
         [0006]    The control arms are fixed to the hinged plates and can be fixed relative to each other at the handle by cooperating teeth and grooves. The handle has a threaded member capable of receiving a wing nut to fix the control arms against each other. Thereby, the angle of the hinged plates may be adjusted. The hinged corner trowel establishes both sides of any angled corner at the same time for utilization on drywall or similar materials. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The invention is illustrated in the drawings in which like reference characters designate the same or similar parts throughout the figures of which: 
           [0008]      FIG. 1  is a rear elevational view of a hinged corner trowel of the present invention; 
           [0009]      FIG. 2  is a top plan view of the hinged corner trowel; 
           [0010]      FIG. 3  is top plan view of one of the arms of the hinged corner trowel; 
           [0011]      FIG. 4  is a side elevational view of the arm shown in  FIG. 3 ; 
           [0012]      FIG. 5  is a partial top plan view of the hinge of the present invention; 
           [0013]      FIG. 6  is a partial top plan view of a hinge hoop of the present invention; 
           [0014]      FIG. 7  is a rear elevational view of a hinged corner trowel according to a second embodiment of the present invention; 
           [0015]      FIG. 8  is a view of the arms of the second embodiment of the present invention shown seated on the post, and shown in a partial exploded view; 
           [0016]      FIG. 9A  is a bottom plan view of the hinged corner trowel of the second embodiment of the present invention; 
           [0017]      FIG. 9B  is a partial top plan view of a hinge hoop of the second embodiment of the invention; 
           [0018]      FIG. 9C  is a partial top plan view of the hinge of the second embodiment of the invention; 
           [0019]      FIG. 10  is a rear elevational view of a hinged corner trowel in accordance with a third embodiment of the present invention; 
           [0020]      FIG. 11A  is a bottom plan view of the hinged corner trowel of the third embodiment of the present invention; 
           [0021]      FIG. 11B  is a bottom plan view of the hinged corner trowel of the third embodiment of the present invention with the plates shown in an alternate position; 
           [0022]      FIG. 12  is a perspective view of an arm of the third embodiment of the present invention; 
           [0023]      FIG. 13A  is a perspective view of the hinged corner trowel of the third embodiment of the invention; and 
           [0024]      FIG. 13B  is a perspective view of the hinged corner trowel of the third embodiment of the invention with the plates shown in an alternate position. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]      FIGS. 1-6  show a hinged corner trowel  10  in accordance with a first embodiment of the invention. A hinged corner trowel  10  may have a handle  13  with a threaded post  16  disposed thereon.  FIG. 1  shows that the handle  13  may have a length L 1  of approximately 6 inches and a diameter D 1  of approximately 1¼ inches. Other dimensions may also be used as will be evident to those of ordinary skill in the art. The handle  13  may be disposed between a pair of flat plates  19 ,  22  which may be connected to each other at a hinge  25 . Plate  19  may include top edge  17  and bottom edge  18 , and plate  22  may include top edge  21  and bottom edge  24 . The plates  19 ,  22  may be constructed of a 25 gauge steel, or other suitable material. The plates  19 ,  22  may have an overall width W 1  of approximately 8 inches and a height H 1  at the hinge  25  of approximately 5½ inches. The top and bottom edges  17 ,  18 ,  21 ,  24  of plates  19  and  22  may have a taper from the hinge  25  to their outer edges  15 ,  27 , respectively. In a preferred embodiment of the invention, the taper may be approximately 10 degrees from the hinge  25  to the outer edges  15 ,  27 . Other dimensions may also be used for the plates which may provide adequate surface area for the application of joint compound or other material, as will be evident to those of ordinary skill in the art. 
         [0026]    The handle  13  may be connected to the hinged plates  19 ,  22  by a pair of arms  28 ,  31 . The arms  28 ,  31  have first and second opposed ends  52 ,  54  and  55 ,  57 , respectively. According to a first embodiment of the invention, the arms  28 ,  31  may be constructed from any suitable rigid material, but are preferably constructed from wire. The wire may be constructed from steel or other suitable materials and may have a diameter of 3/16 inches.  FIGS. 3 and 4  show one of the arms  31  according to the first embodiment of the invention. The arm  31  may have an opening  34  located at a first end  55 . Preferably, the opening  34  may be approximately 5/16 inches in order to be able to receiving the post  16 . However, openings of other sizes may be suitable. The arm  31  may have a length L 2  of approximately 2¼ inches from the second end  57  to the center of the opening  34 .  FIG. 3  shows that arm  31  may be provided with a surface  29  comprising a series of alternating V-shaped teeth  32  and grooves  33  located at the first end  55 . Arm  28  may also be constructed in a similar manner to arm  31  and may have similar features. According to the first embodiment of the invention, each arm  28 ,  31  may have 30 teeth defining V-shaped grooves, having a 45 degree angle, in surface  29 . The teeth  32  of one of the arms  28 ,  31  are capable of engaging with the grooves  33  on the opposite arm  28 ,  31 . The teeth and grooved surfaces may be stamped or machined onto the wire. The teeth and grooves may have other suitable arrangements and may also be formed in other ways as will be evident to those of ordinary skill in the art. 
         [0027]      FIG. 1  shows that the arms  28 ,  31  may be arranged on the post  16  via openings  34  in the first ends  52 ,  55  of the arms  28 ,  31 . The post  16  may include standard threading as known to those of ordinary skill in the art. The arms  28 ,  31  may be seated such that the surfaces  29  having the teeth  32  and grooves  33  on the respective arms  28 ,  31  are facing each other. In use, when the teeth  32  of the arm  28  are inserted into the grooves  33  on the arm  31 , the position of the arms  28 ,  31  may be fixed relative to each other and the arms are not capable of angular movement relative to one another. When the teeth  32  are removed from the grooves  33 , the arms  28 ,  31  may be rotated relative to one another around the post  16 . 
         [0028]    Many different arrangements may be used to attach the second ends  54 ,  57  of arms  28 ,  31  to the plates  19 ,  22 .  FIG. 6  shows a hinge hoop  42  which may be spot welded to plate  19 ,  22 . The hinge hoop  42  may be approximately ¾ inch in length and may have an opening  43  approximately 3/16 inch in diameter, running along its length, in order to receive the second ends  54 ,  57  of arms  28 ,  31 .  FIGS. 1 and 3  show a clip  38  which may be engaged with the second ends  54 ,  55  of the arms  28 ,  31  after insertion through the hinge hoop  42  in order to secure the arms  28 ,  31  to the plates  19 ,  22 . The clip  38  may be removed to detach the arms  28 ,  31  from the plates  19 ,  22 . The second ends  54 ,  55  of the arms  28 ,  31  may be removeably attached to the plates  19 ,  22  in other ways as will be evident to those of ordinary skill in the art. Alternatively, the arms  28 ,  31  may be permanently attached to the plates  19 ,  22 . 
         [0029]      FIG. 5  shows the hinge  25  which connects the plates  19 ,  22  together. The hinge  25  may be of ordinary construction. For example, the plates  19 ,  22  may be connected by a hinge pin  26  which may be a 1/16 inch steel wire. In order to ensure a tight seam between the plates  19 ,  22 , the abutting edges  20 ,  23 , respectively, may be formed with 45 degree angles, as will be evident to those of ordinary skill in the art.  FIG. 2  shows that the hinge  25  may enable the user to vary the angle between the plates  19 ,  22  from between an acute angle of approximately 20 degrees through an obtuse angle of 180 degrees, in this example. 
         [0030]    Returning to  FIG. 1 , shown is a wing nut  40  which may be used on the threaded post  16  to lock the arms  28 ,  31  into engagement with each other. The wing nut  40  may be a standard wing nut known in the art. In use, when the wing nut  40  is tightened down onto the post  16 , it pushes the top arm  28  against the bottom arm  31  causing the teeth and grooves to engage. When the user wants to adjust the angle of the plates  19 ,  22 , the wing nut  40  may be loosened and the arms  28 ,  31  may be rotated relative to one another. 
         [0031]      FIGS. 7-9C  show a hinged corner trowel  110  in accordance with a second embodiment of the invention. The hinged corner trowel  110  may have a handle  113  with a threaded post  116  disposed thereon. The handle  113  may be disposed between a pair of flat plates  119 ,  122  which may be connected to each other at a hinge  125 . Plate  119  may include top edge  117  and bottom edge  118 , and plate  122  may include top edge  121  and bottom edge  124 . The plates  119 ,  122  may be constructed of a 25 gauge steel, or other suitable material. The plates  119 ,  122  may have an overall width W 2  of approximately 8 inches and a height H 2  at the hinge  125  of approximately 5 inches. The top and bottom edges  117 ,  118 ,  121 ,  124  of plates  119  and  122  may have a taper from the hinge  125  to their outer edges  115 ,  127 , respectively of approximately 5 degrees. Other dimensions may also be used for the plates which may provide adequate surface area for the application of joint compound or other material, as will be evident to those of ordinary skill in the art. 
         [0032]    The handle  113  may be connected to the hinged plates  119 ,  122  by a pair of arms  128 ,  131 . The arms  128 ,  131  have first and second opposed ends  152 ,  154  and  155 ,  157 , respectively. In this embodiment of the invention, the arms  128 ,  131  may be arranged with arm  128  abutted against the handle  113  and arm  131  abutted against a wing nut  140 . 
         [0033]      FIG. 8  shows arms  128  and  131  according to the second embodiment of the invention. The arms  128 ,  131  may have an opening  134  located at a first ends  152 ,  155  for receiving the post  116 . The arms  128 ,  131  may each be provided with a surface  129  comprising a series of alternating V-shaped teeth  132  and grooves  133  located at a first ends  152 ,  155 . The arms  128 ,  131  may each have forty teeth forming 45 degree angle V-shaped grooves in surfaces  129 . The teeth  132  of one of the arms  128 ,  131  are capable of engaging with the grooves  133  on the opposite arm  128 ,  131 . The arms  128 ,  131  may have a length L 3  of approximately 1½ inches from their second ends  154 ,  157  to the center of the openings  134 . 
         [0034]      FIG. 7  shows that the arms  128 ,  131  may be arranged on the post  116  via openings  134  in the first ends  152 ,  155  of the arms  128 ,  131 . The arms  128 ,  131  may be seated such that the surfaces  129  having the teeth  132  and grooves  133  on the respective arms  128 ,  131  are facing each other. In use, when the teeth  132  of the arm  128  are inserted into the grooves  133  on the arm  131 , the position of the arms  128 ,  131  may be fixed relative to each other and the arms are not capable of angular movement relative to one another. When the teeth  132  are removed from the grooves  133 , the arms  128 ,  131  may be rotated relative to one another around the post  116 . 
         [0035]    Many different arrangements may be used to attach the second ends  154 ,  157  of arms  128 ,  131  to the plates  119 ,  122 .  FIG. 9B  shows a hinge hoop  142  which may be spot welded to plate  119 ,  122 .  FIG. 7  shows that the hinge hoop  142  may be approximately ¾ inch in length. The hinge hoop  142  may have an opening  143  approximately 3/16 inch in diameter, running along its length, in order to receive the second ends  154 ,  157  of arms  128 ,  131 . The hinge hoop  142  may be welded to the plates  119 ,  122  approximately 1¼ inches from the hinge  125 , measuring to the center of the opening  143 . The second ends  154 ,  157  of arms  128 ,  131  may be approximately 1¼ inches long in order to protrude from the end of the hinge hoop  142 .  FIGS. 8 and 9A  show a clip  138  which may be engaged with the second ends  154 ,  155  of the arms  128 ,  131  after insertion through the hinge hoop  142  in order to secure the arms  128 ,  131  to the plates  119 ,  122 . The clip  138  may be removed to detach the arms  128 ,  131  from the plates  119 ,  122 . The second ends  154 ,  155  of the arms  128 ,  131  may be removeably attached to the plates  119 ,  122  in other ways as will be evident to those of ordinary skill in the art. Alternatively, the arms  128 ,  131  may be permanently attached to the plates  119 ,  122 . 
         [0036]      FIG. 9C  shows the hinge  125  which connects the plates  119 ,  122  together.  FIG. 9A  shows that the hinge  125  may enable the user to vary the angle between the plates  119 ,  122  from between an acute angle of approximately 20 degrees through an obtuse angle of 180 degrees, in this example. 
         [0037]    Returning to  FIG. 7 , shown is a wing nut  140  which may be used on the threaded post  116  to lock the arms  128 ,  131  into engagement with each other. In use, when the wing nut  140  is tightened down onto the post  116 , it pushes the top arm  131  against the bottom arm  128  causing the teeth and grooves to engage. When the user wants to adjust the angle of the plates  119 ,  122 , the wing nut  140  may be loosened and the arms  128 ,  131  may be rotated relative to one another. 
         [0038]      FIGS. 10-13B  show a hinged corner trowel  210  in accordance with a third embodiment of the invention. The hinged corner trowel  210  may have a handle  213  with a threaded post  216  disposed thereon. The handle  213  may be disposed between a pair of flat plates  219 ,  222  which may be connected to each other at a hinge  225 . Plate  219  may include top edge  217  and bottom edge  218 , and plate  222  may include top edge  221  and bottom edge  224 . The plates  219 ,  222  may be constructed of a 26 gauge steel, or other suitable material. The plates  219 ,  222  may have an overall width W 3  of approximately 8½ inches and a height H 3  at the hinge  225  of approximately 5 inches. The top and bottom edges  217 ,  218 ,  221 ,  224  of plates  219  and  222  may be tapered from the hinge  225  to the outer edges  215 ,  227 , respectively so that the outer edges  215 ,  227  have a height H 4  of approximately 3 11/16 inches. Other dimensions may also be used for the plates which may provide adequate surface area for the application of joint compound or other material, as will be evident to those of ordinary skill in the art. 
         [0039]    The handle  213  may be connected to the hinged plates  219 ,  222  by a pair of arms  228 ,  231 . The arms  228 ,  231  have first and second opposed ends  252 ,  254  and  255 ,  257 , respectively. In this embodiment of the invention, the arms  228 ,  231  may be arranged with arm  231  abutted against the handle  213  and arm  228  abutted against a wing nut  240 .  FIG. 10  shows that the second ends  254 ,  257  of the arms  228 ,  231 , respectively, may be arranged on the plates  219 ,  222  so as to point in opposing directions. 
         [0040]      FIG. 12  shows arm  228  according to the third embodiment of the invention. The arm  228  may have an opening  234  located at a first end  252  for receiving the post  216 . Arm  231  may also be constructed in a similar manner to arm  228  and may have similar features. The arms  228 ,  231  may be arranged on the post  216  via openings  234  in the first ends  252 ,  255  of the arms  228 ,  231 . In use, the position of the arms  228 ,  231  may be fixed relative to each other by application of pressure via tightening the wing nut  240  whereby the arms are not capable of angular movement relative to one another. When the wing nut  240  is loosened or removed, the arms  228 ,  231  may be rotated relative to one another around the post  216 . 
         [0041]    Many different arrangements may be used to attach the second ends  254 ,  257  of arms  228 ,  231  to the plates  219 ,  222 .  FIG. 10  shows hinge hoops  242  which may be spot welded to plates  219 ,  222 . The hinge hoops  242  may have openings  243  running along their length, in order to receive the second ends  254 ,  257  of arms  228 ,  231 . The second ends  254 ,  257  of arms  228 ,  231  may be friction fit through the openings  243  in the hinge hoops  242 . 
         [0042]      FIG. 11B  shows the hinge  225  which connects the plates  219 ,  222  together.  FIG. 11A  shows that the hinge  225  may enable a user to vary the angle between the plates  219 ,  222  from between an acute angle of approximately 30 degrees through an obtuse angle of 180 degrees.  FIG. 11A  shows a positioning of the plates  219 ,  222  where the angle between the plates is 32 degrees. In this state, the overall height H 5  of the hinged corner trowel  210  may be approximately 3 15/16 inches, and the overall width W 4  may be approximately 2 5/16 inches.  FIG. 11B  shows an alternate positioning of the plates  219 ,  222  where the angle between the plates is 180 degrees. In this state, the overall height H 6  of the hinged corner trowel  210  may be approximately 1 11/16 inches. 
         [0043]      FIG. 13A  shows the hinged corner trowel  210  according to the third embodiment of the invention. In this example, it is shown how the hinged corner trowel  210  may be used with the plates  219 ,  222  lying at an acute angle α1.  FIG. 13B  shows how the hinged corner trowel  210  may be used with the plates  219 ,  222  lying at a reflex angle a 2 . 
         [0044]    While the invention has been described in connection with certain embodiments, it is not intended to limit the scope of the invention to the particular forms set forth, but, on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention.

Summary:
An adjustable hinged corner trowel is formed from hinged plates with a removeably attached handle. Cooperating control arms connect the handle to the hinged plates. The control arms are fixed to the hinged plates and can be fixed relative to each other at the handle by cooperating teeth and grooves. The handle has a threaded member capable of receiving a wing nut to fix the control arms against each other. Thereby, the angle of the hinged plates may be adjusted. The hinged corner trowel establishes both sides of any angled corner at the same time for utilization on drywall or similar materials.