Abstract:
A locking screwdriver which engages and locks to the head of a screw preventing unseating of the screwdriver from the screw during screw removal and firmly holding and guiding self-tapping screws during their placement.

Description:
FIELD OF THE INVENTION 
   The present invention is directed to a screwdriver which locks to a screw preventing the screwdriver from unseating from the screw during the initial placement and removal of the screw. 
   BACKGROUND OF THE INVENTION 
   A variety of instruments have been developed to remove screws where the head of the screw has been damaged. The head of the screw is most frequently damaged by the screwdriver during the attempt to remove the screw. Considerable steady pressure must be placed on the screwdriver to keep the screwdriver seated on the head of the screwdriver. If the screwdriver head is allowed to lift from the head of the screw the screw will be stripped. The screw will then have to be removed by other means. This damage is more common with a Phillips screwdriver head. Although a number of tools have been developed to remove damaged screws, none have been developed to prevent the screwdriver damage in the first place. A need exists for a simple, easy to use tool which enables the removal of a hard to remove screw without damaging the head of the screw. The tool must firmly hold the head of the screw and not allow any lifting of the screwdriver head away from the screw during the screw removal process. Additionally tools have also been developed for the placement of screws. A common tool grips the screw head holding the screw to the head of the screwdriver. A similar screwdriver is magnetic which would hold a magnetic screw; but, is not useful for a non-magnetic screw. These screwdrivers are useful for placing a hard to hold screw in a pre-threaded or pre-drilled screw hole. In the case of self tapping and wood type screws they don&#39;t hold the screw firmly enough to allow the screw to start its own hole and be directionally guided during its placement, an added step of drilling or punching a guide hole is required which is especially time consuming and cumbersome when using surgical screws. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention is directed to a locking screwdriver for holding a screw during the placement and removal of a screw. The invention firmly locks the screwdriver tip against a screw which aids in the placement of the screw and prevents the screwdriver from unseating and damaging the screw head during the removal of the screw. The locking screwdriver is comprised of a longitudinal tube with a circumferentially externally grooved first end and a second end externally threaded, the second end has attached locking fingers extending longitudinally; a longitudinal rod with an externally threaded first end, a male fitting projecting longitudinally from the first end with an attached handle, a second rod end with a female fitting containing a male fitting extending longitudinally ending in a screwdriver fitting means; two internally threaded collets, the first collet is rotatably attached to the circumferential groove of the first end of the tube and threaded to the first rod end, the second collet is threaded to the second end of the rod and surrounds the locking fingers. 
   The locking screwdriver is used by placing the gripping fingers around the screw head, locking the fingers to the screw head by turning the second collet clockwise and rotating the first collet clockwise which seats the screwdriver tip means to the screw, the handle is turned clockwise to place a screw and counterclockwise to remove a screw. 
   In an alternative embodiment the locking screwdriver can be fitted with cutting tips at the end out of the gripping arms to remove material from around a sunken screw. In an alternative embodiment the internal of the locking fingers can have notches for more securely gripping the screw head. Additionally in other embodiments the handle can be placed with a ratchet wrench which applies more force, useful during the removal of a frozen screw. The screwdriver fittings can be for machine screws, self-tapping, flat head and lag screws. 
   The screwdriver locking tool is useful in firmly holding a screw, especially a wood screw, during the screw&#39;s initial placement. The screw would placed by locking the screw in the tool, placing the tip of the screw on the surface of the material, tapping the end of the tool handle with a hammer. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the locking screwdriver; 
       FIG. 2  is a perspective view of the locking screwdriver; 
       FIG. 3  is a cross sectional view taken along the lines of  3 — 3  of  FIG. 1 ; 
       FIG. 4  is a cross sectional view taken along the lines of  4 — 4  of  FIG. 1 ; 
       FIG. 5  is a perspective view of a ratchet wrench handle; 
       FIG. 6  is a perspective view of a screwdriver handle; 
       FIG. 7  is a perspective view of the locking screwdriver; 
       FIG. 8  is a perspective view of a locking screwdriver end fitting; 
       FIG. 9  is a perspective view of a locking screwdriver end fitting; 
       FIG. 10  is a perspective view of a locking screwdriver end fitting; 
       FIG. 11  is a perspective view of a C clasp; 
       FIG. 12  is a perspective view of the first collet; 
       FIG. 13  is a perspective view of the second collet; 
       FIG. 14  is a perspective view of the longitudinal tube; 
       FIG. 15  is a perspective view of the longitudinal rod; 
       FIG. 16  is a cross sectional view taken along the lines of  16 — 16  of  FIG. 7 ; 
       FIG. 17  is a cross sectional view taken along the lines of  17 — 17  of  FIG. 14 ; and 
       FIG. 18  is a cross sectional view taken along the lines of  18 — 18  of  FIG. 15 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to FIGS.  1 , 2 , 3 , 4  and  5  the locking screwdriver  1  has a longitudinal tube  2  which contains an internal longitudinal rod  10  which moves longitudinally within the longitudinal tube  2  guided by longitudinal rod ridges  17 ,  FIGS. 3 ,  4 ,  15  and  16 , which slide within longitudinal slots  5 ,  FIG. 16 , of the longitudinal tube  2 . The slot  5  and ridge  17  combinations assures the locking screwdriver  1  rotates as a unit. The longitudinal rod  10 , as shown in  FIGS. 1 ,  2 ,  3 ,  4 ,  7 ,  15  and  18 , has a first end  13  with a longitudinal extension comprising a male hexagonal fitting  19  for the attachment of a screwdriver handle  12 . The longitudinal rod  10  near the first rod end  13  has circumferential threads  16 ,  FIGS. 15 and 18 , which extend outwardly from the rod external surface  11  as shown in  FIGS. 3 ,  4 ,  15  and  18 . The longitudinal rod  10  has a second end with a female hexagonal socket  18  for receiving the male fitting  52  of the first end  50 A of the screwdriver end means  50  as shown in  FIGS. 1 ,  2 ,  3 ,  4 ,  7 ,  9 ,  10  and  18 . The screwdriver end means  50  has a second end SOB with a screwdriver fitting means  50 B as shown in  FIGS. 1 ,  2 ,  3 ,  4 ,  7 ,  8 ,  10  and  15 . As shown in  FIGS. 1 ,  2 ,  3 ,  4 ,  7 ,  14  and  17  the longitudinal tube  2  has first  3  and second  4  ends, the first end  3  has an external circumferential slot  42 , as shown in  FIG. 14 , the second end  4  has external circumferential threads  48  and longitudinal extensions forming a plurality of gripping fingers  40  as in  FIGS. 1 ,  2 ,  3 ,  4 ,  7 , and  14 . The gripping fingers  40  form a discontinuous annulus wherein the fingers  42  have internal  46  and outer  47  surfaces and first  41  and second  42  sections as shown in  FIGS. 3 ,  4  and  14 . The first finger sections  41  gently taper outwards and continue in second finger sections  41  which gently curve inwards. The internal surfaces  46  of the gripping fingers  40  are curved to approximately fit the head of a screw  60  as shown in FIGS.  1 , 2 , 3 , 4 ,  7 ,  12 ,  13 ,  14  and  15 . In  FIGS. 1 ,  2 ,  3 ,  4  and  7  first  20  and second  30  collets are attached to the longitudinal tube  2 , the first collet  20  is attached to the longitudinal tube  2  first end  3  using a locking C clasp  26  which is placed in an external circumferential slot  25  which is in a narrowed portion  24  of the second end  22  of the first collet  20 . The C clasp  26 , as in  FIG. 11 , has internal projections  26 A which are directed to the axial center  26 B of the C clasp  26  and are fitted through the respective openings  27  in the external circumferential slot  25  and into the interior  28  of the first collet  20 . The C clasp projections  26  lock into the circumferential slot  42  of the longitudinal tube  2  which connects rotatably connects the longitudinal tube  20  to the first collet  20 . 
   The first collet  20  has a threaded  28 A interior  28 ,  FIG. 11 , which is screwed to the first end threads  19 A of the longitudinal rod  10 .  FIGS. 3 and 4 . When the first collet  20  is turned clockwise the longitudinal rod  10  is moved towards the second longitudinal tube end  4  which seats the screwdriver end means  50  in the head of the screw  60 ,  FIGS. 1 ,  2 ,  3  and  4 . The second collet  30 , in  FIGS. 1 ,  2 ,  3 ,  4 ,  7  and  13 , has a first end  31  threaded  28 A interior  28 B and a second end  32  interior  28 C which is tapered inwards towards the second collet end  32 . As the second collet  30  is turned clockwise the second collet  30  interior closes the gripping fingers  40  axially inwards wherein the gripping fingers  40  grip the head  60  of the screw  FIGS. 2 and 4 . 
   The method of locking screwdriver end means  50  to the screw head  60  is to place a screwdriver end means  50  in the screwdriver screw head  60 ,  FIG. 2 , and turn the first collet  20  until the gripping fingers  40  are adjacent to the screw head  60  and then turn the second collet  30  clockwise until the gripping fingers  40  grip. In a variety of embodiments the screwdriver end means  50  may be a hexagonal male fitting  53 ,  FIG. 8 , a flat blade end  52 A,  FIG. 9 , and a Phillips screwdriver  51 ,  FIG. 10 . In a further embodiment the screwdriver means  50  is magnetic which will hold an iron-based screw  60  to the screwdriver end means  50 , which is particularly useful during screw placement. In another embodiment, in  FIGS. 1 ,  2 ,  7 ,  12  and  13 , the exterior surfaces  23  of the first collet  20  and exterior surface  33  of the second collet  30  may be grooved in a cross-cut manner enhancing gripping of the collets  20  and  30 . 
   In another embodiment, in  FIGS. 1 ,  2 ,  3 ,  4 , 7 ,  14  and  17 , the gripping fingers  40  have a third section  43  extending longitudinally from the second end  42 . The third section  43  turns abruptly axially inwards and ends in cutting tips which are used for removing material around the head of an In embedded screw  60 . In another embodiment in  FIGS. 1 ,  2 ,  3 ,  4 ,  7 ,  14 , and  17 , each gripping fingers  40  internal surface  46  has a notch  45  where the second finger section  42  meets the third finger section  43 . The notch  45  enhances the gripping of the head of the screw  60 . In another embodiment the handle means is a ratchet wrench  70 , as shown in  FIG. 5 , which is advantageous for moving hard to remove screws and placing screws in hard material. The locking screwdriver  1  is particularly useful in placing surgical screws in bones; the tool maintains the direction of the screw during the placement, thus eliminating the need for drilling a guide hole. A particular example is where screw are placed between adjacent roots of teeth, the screw can be placed without drilling a guide hole, the drilling of a guide hole runs the risk of damaging the roots of the teeth. 
   The invention is described with specific embodiments. However, the intent of the invention is to provide locking screwdriver that will remove a hard to remove screw without damaging the screw head and to firmly hold screws in place during their placement. The object is to hold the screwdriver so firmly against the screw head the screwdriver will not unseat and damage the screw head.