Patent Publication Number: US-6904834-B2

Title: Screw-belt advancing mechanism for a screw driving gun

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a screw driving gun, more particularly to a screw-belt advancing mechanism for a screw driving gun. 
   2. Description of the Related Art 
   Referring to  FIG. 1 , a conventional screw driving gun  2  (illustrated in phantom lines) generally includes a driving shaft  21 , a belt-retaining mechanism  1 , and a screw-retaining belt unit  3 . The screw-retaining belt unit  3  includes a belt body  30 , a plurality of screw  31  retained releasably on the belt body  30 , and a plurality of engaging holes  32 , each of which is disposed between adjacent two of the screws  31 . 
   The belt-retaining mechanism  1  includes a sliding unit  10 , a barrel unit  22 , and a belt-retaining member  12 . The barrel unit  22  receives the driving shaft  21  therein, and has a rear end connected to the screw driving gun  2 , and a front end opposite to the rear end. The sliding unit  10  is connected telescopically to the front end of the barrel unit  22 , is movable relative to the barrel unit  22  between extended and retracted positions, and includes a nose plate. An urging member  221  is sleeved on the driving shaft  21  and urges the sliding unit  10  to move to the extended position. The screw-retaining belt unit  3  is fed into the sliding unit  10  via a side opening  11  and is retained on the nose plate of the sliding unit  10  by the belt-retaining member  12 , which is biased frontwardly in such a manner that an engaging end  120  of the belt-retaining member  12  engages a selected one of the engaging holes  32  in the screw-retaining belt unit  3  so as to retain the belt unit  3  on the nose plate of the sliding unit  10 . The engaging end  120  of the belt-retaining member  12  is formed with an inclined lower sliding face  121  which is in sliding contact with the screw-retaining belt unit  3  so as to permit disengagement of the belt body  30  from the engaging end  120  of the belt-retaining member  12  during upward pushing of the screw-retaining belt unit  3  to a position, where a selected screw  31  is aligned with the driving shaft  21 . 
   The aforesaid conventional screw driving gun  2  is disadvantageous in that it is inconvenient and laborious to pull the screw-retaining belt unit  3  manually in order to align a selected one of the screws  31  with the driving shaft  21 . 
   SUMMARY OF THE INVENTION 
   Therefore, the object of this invention is to provide a screw-belt advancing mechanism for a screw driving gun which does not require manual pulling of a screw-retaining belt so as to overcome the aforesaid disadvantage of the prior art. 
   Accordingly, the screw-belt advancing mechanism of the present invention is used to advance a screw-retaining belt on a screw driving gun. The screw-retaining belt supports detachably a plurality of screws thereon, and has a plurality of engaging holes, each of which is disposed between adjacent two of the screws. The screw-belt advancing mechanism includes: a barrel unit that has a front end and a rear end adapted to be connected to the screw driving gun, that is adapted to receive a driving shaft therein, and that defines a longitudinal direction; a sliding unit connected telescopically to the front end of the barrel unit, movable in the longitudinal direction relative to the barrel unit between extended and retracted positions, and including a nose plate; an urging member for urging the sliding unit to move to the extended position; a spring-biased positioning member mounted on the sliding unit and adapted to position the screw-retaining belt on the nose plate; a pivot pin mounted on the sliding unit so as to move together therewith in the longitudinal direction, and extending in a transverse direction relative to the longitudinal direction; and a spring-biased lifting member adapted to engage releasably a selected one of the engaging holes in the screw-retaining belt, pivoted to the pivot pin, and associated with the sliding unit in such a manner that the lifting member is moved in the longitudinal direction toward the rear end of the barrel unit and pivots about the pivot pin in a first direction so as to push the screw-retaining belt to move to a desired position, in which, a selected one of the screws on the screw-retaining belt is aligned with the driving shaft, when the sliding unit slides from the extended position to the retracted position against urging action of the urging member, and that the lifting member is moved in the longitudinal direction away from the rear end of the barrel unit, and pivots about the pivot pin in a second direction opposite to the first direction to engage releasably an adjacent one of the engaging holes in the screw-retaining belt which is disposed adjacent to the selected one of the engaging holes in the screw-retaining belt when the sliding unit slides from the retracted position to the extended position by virtue of the urging action of the urging member. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of this invention will become more apparent in the following detailed description of the preferred embodiments of this invention, with reference to the accompanying drawings, in which: 
       FIG. 1  is a partly sectional, schematic side view of a conventional screw driving gun; 
       FIG. 2  is a perspective view of the preferred embodiment of a screw-belt advancing mechanism for a screw driving gun according to the present invention; 
       FIG. 3  is an exploded perspective view of a portion of the preferred embodiment; 
       FIG. 4  is a fragmentary partly sectional view illustrating details and connecting relationship of components of the preferred embodiment; 
       FIG. 5  is a fragmentary partly sectional view of the preferred embodiment, illustrating a state prior to pivoting movement of a lifting member about a pivot pin; 
       FIG. 6  is a fragmentary partly sectional view of the preferred embodiment, illustrating how pivoting movement of the lifting member about the pivot pin aligns a selected screw with a driving shaft; and 
       FIG. 7  is a fragmentary partly sectional view of a modified preferred embodiment of a screw-belt advancing mechanism for a screw driving gun according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIGS. 2 to 5 , the preferred embodiment of a screw-belt advancing mechanism  5  according to the present invention is used to advancing a screw-retaining belt  9  on a screw driving gun (not shown), and is shown to include a barrel unit  6 , a sliding unit  7 , an urging member  62 , a spring-biased positioning member  54 , a pivot pin  95 , and a spring-biased lifting member  52 . 
   As illustrated, the screw-retaining belt  9  supports detachably a plurality of screws  90  thereon, and has a plurality of engaging holes  91 , each of which is disposed between adjacent two of the screws  90 . 
   The barrel unit  6  includes a casing  60  that has a front end  601  and a rear end  602  adapted to be connected to the screw driving gun (not shown), that is adapted to receive a driving shaft  65  therein, and that defines a longitudinal direction. 
   The sliding unit  7  is connected telescopically to the front end  601  of the casing  60 , is movable in the longitudinal direction relative to the casing  60  between extended and retracted positions, and includes a nose plate  514 . 
   The urging member  62 , preferably a compression spring, is sleeved on the driving shaft  65 , and urges the sliding unit  7  to move to the extended position, as best shown in  FIG. 2 . 
   The positioning member  54  includes two interconnected positioning arms  540  having pivot ends  541  pivoted on the sliding unit  7 , and engaging ends  542  opposite to the pivot ends  541 . A spring plate  55  is disposed within the sliding unit  7 , and urges constantly the positioning arms  540  in such a manner that the engaging ends  542  of the positioning arms  540  engage releasably the screw-retaining belt  9  so as to position the screw-retaining belt  9  on the nose plate  514  of the sliding unit  7 , as best shown in  FIG. 5 . Each of the engaging ends  542  of the positioning arms  540  is formed with an inclined lower sliding side  544  which is in sliding contact with the screw-retaining belt  9  so as to permit disengagement of the positioning arms  540  from the screw-retaining belt  9  and so as to permit advancement of the screw-retaining belt  9  upon movement of the lifting member  52 , which will be described in greater detail hereinafter. 
   The pivot pin  95  is mounted on the sliding unit  7  so as to move together therewith in the longitudinal direction, and extends in a transverse direction relative to the longitudinal direction. 
   The spring-biased lifting member  52  engages releasably a selected pair of the engaging holes  91  in the screw-retaining belt  9 , is pivoted to the pivot pin  95 , and is associated with the sliding unit  7  in such a manner that when the sliding unit  7  slides due to an applied force from the extended position of  FIG. 5  to the retracted position of  FIG. 6  against urging action of the urging member  62 , the lifting member  52  moves in the longitudinal direction toward the rear end  602  of the casing  60 , and pivots about the pivot pin  95  in a first direction so as to push the screw-retaining belt  9  to move to a desired position, in which, a selected one of the screws  90  on the screw-retaining belt  9  is aligned with the driving shaft  65 . Under this condition, the selected screw  90  can be driven into a workpiece (W), such as a wall, upon rotation of the driving shaft  65 . When the applied force is removed, the sliding unit  7  slides from the retracted position to the extended position by virtue of the urging action of the urging member  62 , which, in turn, results in movement of the lifting member  52  in the longitudinal direction away from the rear end  602  of the casing  60 , and simultaneous rotation of the lifting member  52  about the pivot pin  95  in a second direction opposite to the first direction to engage releasably an adjacent pair of the engaging holes  91  in the screw-retaining belt  9  which are disposed adjacent to the selected pair of the engaging holes  91  in the screw-retaining belt  9 . Note that each of the engaging ends  542  of the positioning arms  540  is further formed with an inclined upper sliding side  543  which is in sliding contact with the screw-retaining belt  9  so as to permit downward movement of the belt  9  in case the latter is pulled downward, such as, when removing the screw-retaining belt  9  from the sliding unit  7 . 
   In the preferred embodiment, the casing  60  is formed with a pair of opposite guiding slots  61 , each of which includes a straight section  614  that extends in the longitudinal direction and that has a front end  6140 , and a sloped section  613  that extends inclinedly and downwardly from the front end  6140  of the straight section  614  and that has a front end  611  which is disposed at an elevation lower than the front end  6140  of the straight section  614 . The lifting member  52  includes two interconnected lifting arms  520 . Each of the lifting arms  520  has a pivot end  521  pivoted to the pivot pin  95 , a driving end  522  opposite to the pivot end  521  and engaging releasably the selected engaging holes  91  in the screw-retaining belt  9 , and an intermediate portion extending between the driving and pivot ends  521 ,  522 . The intermediate portion of each of the lifting arms  520  is formed with a mounting hole  523 . The sliding unit  7  includes a lifting lever  8  that is parallel to the pivot pin  95 , and that extends through the mounting holes  523  in the lifting arms  520  and the guiding slots  61  in the casing  60  so as to permit pivoting movement of the lifting arms  520  about the pivot pin  95  during sliding movement of the lifting lever  8  between the front ends  611  of the sloped sections  613  and the front ends  6140  of the straight sections  614  when the sliding unit  7  is slid between the extended position and the retracted position. 
   The sliding unit  7  further includes a mounting seat  51  and a sliding frame  70 . The mounting seat  51  is disposed slidably in the casing  60 , has a front plate projecting frontwardly and outwardly from the front end  601  of the casing  60  to define the nose plate  514 , and two side plates  512  that extend rearwardly from two opposite ends of the nose plate  514  into the casing  60  to define a receiving space therebetween for receiving the lifting member  52  therein and that are formed with openings  517  registered with the mounting holes  523  in the lifting arms  520  and permitting extension of the lifting lever  8  therethrough. The pivot ends  521  of the lifting arms  520  are pivoted to the side plates  512  of the mounting seat  51  through the pivot pin  95 , which is disposed rearwardly of the openings  517  in the side plates  512  of the mounting seat  51 . The mounting seat  51  is further formed with a spring-abutting plate  518  that is disposed rearwardly of the nose plate  514 , that interconnects the side plates  512  of the mounting seat  51 , and that abuts against one end of the urging member  62 . The sliding frame  70  is interposed between the mounting seat  51  and the casing  60 , and is associated with the mounting seat  51  in such a manner so as to be movable together therewith relative to the casing  60  between the extended and retracted positions. The sliding frame  70  has an abutment plate  701  disposed frontwardly of and cooperating with the nose plate  514  of the mounting seat  51  to define a screw-receiving chamber therebetween for receiving the selected screw  90 , and a pair of side plates  702  that extend rearwardly and respectively from opposite ends of the abutment plate  701  into the casing  60 , that overlap the side plates  512  of the mounting seat  51  and that are formed with two openings  703  registered with the openings  517  in the side plates  512  of the mounting seat  51  to permit extension of the lifting lever  8  therethrough. 
   The screw-belt advancing mechanism  5  further includes a second urging member  53  having one end fixed to the side plates  512  of the mounting seat  51 , and an opposite end connected to the pivot ends  521  of the lifting arms  520  so as to urge the lifting arms  520  to move toward the nose plate  514  of the sliding unit  7 . 
   Referring to  FIG. 7 , a modified preferred embodiment of the present invention is shown to have a construction similar to that of the previous embodiment, except that the driving shaft  65  is formed with a hexagonal hole  651  in order to receive the hexagonal head  901  of the screw  90  on the screw-retaining belt  9 . 
   During the screw driving operation, the sliding frame  70  is pressed against the workpiece (W), which, in turn, results in movement of the sliding unit  7  to the retracted position and alignment of the selected screw  90  with the driving shaft  65 . The aforesaid disadvantage of the prior art is thus eliminated by the mechanism of the present invention. 
   With this invention thus explained, it is apparent that numerous modifications and variations can be made without departing from the scope and spirit of this invention. It is therefore intended that the invention be limited only as indicated in the appended claims.