Abstract:
A quick clamping fixture includes a main rod, on which two sliders are slidably mounted and may be braked at desired positions to clamp a workpiece between them. The two sliders each have an L-shaped plate and a set of metal plates mounted in a housing thereof with the main rod extended through these plates. The L-shaped plate and the metal plates in the housing are normally pushed by a compression spring into an inclined state to thereby firmly press against an outer surface of the main rod, preventing the slider from sliding along the main rod. When the L-shaped plate is pushed and held, the L-shaped plate and the metal plates are moved into an upright state without firmly pressing against the main rod, allowing the slider to slide along the main rod; and when the L-shaped plate is released, the slider is braked again.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a quick clamping fixture, and more particularly to a quick clamping fixture that utilizes a compression spring to push a set of metal plates in a slider into an inclined state for firmly pressing against on a main rod and thereby preventing the slider from sliding along the main rod, and an L-shaped plate to release the metal plates from the inclined state for the slider to slide on the main rod again. 
   BACKGROUND OF THE INVENTION 
   There are various types of braking mechanisms being employed on the currently available quick clamping fixtures to stop two sliders thereof from moving when a workpiece has been clamped therebetween. Most of these conventional braking mechanisms can only temporarily hold the sliders in place. In other words, when the sliders or the clamped workpiece is subjected to an external force, the braking mechanism on the sliders will become loosened easily to undesirably release the sliders and accordingly, the workpiece. 
   Moreover, the two sliders on the conventional quick clamping fixtures could be slid only along and on a main rod and are not removable from the main rod. Therefore, the conventional quick clamping fixture does not provide applications other than clamping a workpiece. 
   It is therefore tried by the inventor to develop a quick clamping fixture that includes a braking mechanism to provide enhanced braking effect for the sliders, and can be used in different manners to provide other functions. 
   SUMMARY OF THE INVENTION 
   To achieve the above and other objects, the quick clamping fixture according to the present invention includes a main rod, on which two sliders are slidably mounted and may be braked at desired positions to clamp a workpiece between them. The two sliders each have a housing, in which an L-shaped plate and a set of metal plates are mounted with the main rod extended through these plates. The L-shaped plate and the set of metal plates in the housing are normally pushed by a compression spring into an inclined state to thereby firmly press against an outer surface of the main rod, preventing the slider from sliding along the main rod. When the L-shaped plate is pushed and held, the L-shaped plate and the set of metal plates are moved into an upright state without firmly pressing against the main rod, allowing the slider to slide along the main rod; and when the L-shaped plate is released, the slider is braked again. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein 
       FIG. 1  is an assembled perspective view of a quick clamping fixture according to the present invention; 
       FIG. 2  is a cutaway view of  FIG. 1 ; 
       FIG. 3  is a fragmentary sectioned side view showing a slider of the present invention is in a braked state; 
       FIG. 4  is a fragmentary sectioned side view showing the slider of the present invention is in a movable state; 
       FIG. 5  shows the slider is removed from a main rod of the present invention via an end thereof; 
       FIGS. 6 ,  7 , and  8  show the slider removed from the main rod is re-mounted to the main rod via another end of the main rod; and 
       FIG. 9  shows the quick clamping fixture of the present invention is used as a jack lift. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Please refer to  FIGS. 1 and 2 , in which a quick clamping fixture according to the present invention is shown. The quick clamping fixture of the present invention includes a slider  1 , a fine-adjustment slider  2 , a main rod  3 , two L-shaped plates  11  having a large and a small bore  111 ,  112  each, two compression springs  4 , two bolts  5 , two collars  6 , and two sets of metal plates  12  having a large and a small bore  121 ,  122  each. 
   The slider  1  includes a housing  101  defining an internal space  73 ; a first jaw  7  provided on the housing  101  at an upper front end thereof; and a base  71  provided at a bottom of the housing  101  to define a lower space  72  between the bottom of the housing  101  and the base  71 . The housing  101  is provided on front and rear walls at a center thereof with two corresponding openings  10 , and on the front and rear walls near an upper end thereof with two corresponding screw holes  21 . 
   A first one of the two L-shaped plates  11 , a first one of the two sets of metal plates  12 , and a first one of the two compression springs  4  are sequentially mounted in the internal space  73  of the housing  101  of the slider  1  from front to rear, with a lower horizontal portion of the first L-shaped plate  11  forward extended through the lower space  72  to locate outside the housing  101 . 
   The slider  1  is assembled to the main rod  3  by extending the main rod  3  through the two corresponding openings  10  on the housing  101 , the large bore  111  on the first L-shaped plate  11 , the large bores  121  on the first set of metal plates  12 , and the first compression spring  4 . A first one of the two bolts  5  is extended through the two corresponding screw holes  21  on the housing  101 , the small bore  112  on the first L-shaped plate  11 , and the small bores  122  on the first set of metal plates  12 , and fixed at two ends to the front and rear walls of the housing  101 . A first one of the two collars  6  is mounted on the first bolt  5  to locate between the front wall of the housing  101  and the first L-shaped plate  11 . 
   With the above arrangements, the first compression spring  4  mounted on the main rod  3  and located between the rear wall of the housing  101  and the first set of metal plates  12  is able to normally forward push the first L-shaped plate  11  and the first set of metal plates  12  into a rearward inclined state on the main rod  3 , as shown in  FIG. 3 , such that the rearward inclined first L-shaped plate  11  and first set of metal plates  12  in the housing  101  are firmly pressed at the large bore  111  and the large bores  121 , respectively, against an outer surface of the main rod  3 , bringing the slider  1  into a braked state. 
   The fine-adjustment slider  2  includes a housing  102  defining an internal space  74 ; a hand-operable screw rod  201  axially extended through near an upper end of the housing  102 ; a second jaw  8  connected near an upper end to a front end of the screw rod  201  with the main rod  3  extended through near a lower end of the second jaw  8 ; and a base  81  provided at a bottom of the housing  102  to define a lower space  82  between the bottom of the housing  102  and the base  81 . The housing  102  is provided on front and rear walls at a center thereof with two corresponding openings  20 , and on the front and rear walls near an upper end thereof with two corresponding screw holes  22 . 
   A second one of the two L-shaped plates  11 , a second one of the two sets of metal plates  12 , and a second one of the two compression springs  4  are sequentially mounted in the internal space  74  of the housing  102  of the fine-adjustment slider  2  from front to rear, with a lower horizontal portion of the second L-shaped plate  11  forward extended through the lower space  82  to locate outside the housing  102 . The fine-adjustment slider  2  is assembled to the main rod  3  by extending the main rod  3  through the two corresponding openings  20  on the housing  102 , the large bore  111  on the second L-shaped plate  11 , the large bores  121  on the second set of metal plates  12 , and the second compression spring  4 . A second one of the two bolts  5  is extended through the two corresponding screw holes  22  on the housing  102 , the small bore  112  on the second L-shaped plate  11 , and the small bores  122  on the second set of metal plates  12 , and fixed at two ends to the front and rear walls of the housing  102 . A second one of the two collars  6  is mounted on the second bolt  5  to locate between the front wall of the housing  102  and the second L-shaped plate  11 . 
   With the above arrangements, the second compression spring  4  mounted on the main rod  3  and located between the rear wall of the housing  102  and the second set of metal plates  12  is able to normally forward push the second L-shaped plate  11  and the second set of metal plates  12  into a rearward inclined state on the main rod  3 , similar to that shown in  FIG. 3 , such that the rearward inclined second L-shaped plate  11  and second set of metal plates  12  in the housing  102  are firmly pressed at the large bore  111  and the large bores  121 , respectively, against an outer surface of the main rod  3 , bringing the fine-adjustment slider  2  into a braked state. 
   By mounting the two L-shaped plates  11  and the two sets of metal plates  12  in the housings  101 ,  102  in the above manner, the L-shaped plates  11  and the metal plates  12  may be moved along with the housings  101 ,  102  on the main rod  3  to and fro. 
   And, by manually rotating the screw rod  201  forward, the second jaw  8  connected to the front end of the screw rod  201  is brought to gradually move along the main rod  3  toward or away from the first jaw  7 , so as to finely adjust a distance between the first and the second jaw  7 ,  8  for firmly and safely clamping a workpiece between the two jaws  7 ,  8 . 
   Please refer to  FIG. 4 . When it is desired to move the slider  1  or the fine-adjustment slider  2  along the main rod  3 , simply push and hold the horizontal lower portion of the L-shaped plate  11  located outside the housing  101 ,  102 . At this point, the L-shaped plate  11  and the sets of metal plates  12  are together moved into an upright position on the main rod  3  in the housing  101 ,  102 , and the compression spring  4  is compressed, such that the L-shaped plate  11  and the set of metal plates  12  no longer firmly press at the large bores  111 ,  121  against the outer surface of the main rod  3 . That is, the slider  1  or the fine-adjustment slider  2  is released from the braked state and may be slid along the main rod  3  to a desired position. 
   When the slider  1  or the fine-adjustment slider  2  has been moved along the main rod  3  to the desired position to firmly clamp a workpiece between the first and the second jaw  7 ,  8 , and it is desired to brake the slider  1  or the fine-adjustment slider  2  on the main rod  3 , an operator needs only to release the L-shaped plate  11 . At this point, an elastic restoring force of the compressed compression spring  4  automatically pushes the L-shaped plate  11  and the set of metal plates  12  into the rearward inclined state on the main rod  3 , so that the L-shaped plate  11  and the set of metal plates  12  are firmly pressed at the large bores  111 ,  121  against the main rod  3  again, and the slider  1  or the fine-adjustment slider  2  is braked. 
   Please refer to  FIG. 5 . Both of the slider  1  and the fine-adjustment slider  2  may be removed from the main rod  3  via an end thereof.  FIGS. 6 ,  7 , and  8  show the slider  1  is removed from the main rod  3  via a first end thereof and then re-mounted to the main rod  3  via a second end thereof, so that the first and the second jaw  7 ,  8  are facing away from each other. With the two jaws  7 ,  8  facing away from each other, the quick clamping fixture of the present invention may be used to expand a workpiece. 
   Please refer to  FIG. 9 . When the quick clamping fixture of the present invention with the two jaws  7 ,  8  facing away from each other is disposed in an upright position, the quick clamping fixture may be conveniently used as a jack lift. 
   Since the metal plates  12  are closely arranged in the housings  101 ,  102  to thereby produce a considerably large overall thickness for each set of the metal plates  12 , when the metal plates  12  are rearward inclined in the housing  101 ,  102 , all the large bores  121  on the inclined metal plates  12  are firmly pressed against the main rod  3  at the same time to produce an increased total contact area between the large bores  121  and the outer surface of the main rod  3 , so that the slider  1  and the fine-adjustment slider  2  in the braked state are not subject to any risk of loosening from the main rod  3  easily.