Abstract:
A work clamp for wood-working machines, includes a guide bar, a fixed clamping plate fixedly mounted on the guide bar, a movable clamping plate slidably mounted on the guide bar and moved relative to the fixed clamping plate to hold down workpiece with the fixed clamping plate, and a control device adapted to control movement of the movable clamping plate on the guide bar relative to the fixed clamping plate and to lock the movable clamping plate in the desired position.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to woodworking machines and, more particularly, to a work clamp for use in a woodworking machine to hold down the workpiece for cutting. 
     In order to cut a number of wooden materials at a time, a work clamp is necessary to hold down wooden materials on the table of the woodworking machine. A satisfactory work clamp for this purpose shall have the advantages of compact structure, high workpiece clamping power, ease of use, less table space occupation. 
     SUMMARY OF THE INVENTION 
     It is one object of the present invention to provide a work clamp for woodworking machines, which is easy to operate. It is another object of the present invention to provide a work clamp for woodworking machines, which positively holds down the workpiece for processing when locked. It is still another object of the present invention to provide a work clamp for wood-working machines, which is compact and, requires less installation space To achieve these and other objects of the present invention, the work clamp comprises a guide bar; a fixed clamping plate fixedly fastened to the guide bar, the fixed clamping plate having a clamping face disposed at a bottom side thereof; a movable clamping plate mounted on the guide bar and driven to move along the guide bar relative to the fixed clamping plate, the movable clamping plate having a clamping face disposed at a bottom side thereof and facing the clamping face of the fixed clamping plate for clamping workpiece between the fixed clamping plate and the movable clamping plate; and a control device adapted to lock the movable clamping plate and to control movement of the movable clamping plate on the guide bar relative to the fixed clamping plate to further adjust the pitch between the clamping face of the fixed clamping plate and the clamping plate of the movable clamping plate. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a work clamp constructed according to the present invention. 
     FIG. 2 is a plain view showing the movable clamping plate clamped on the workpiece against the fixed clamping plate according to the present invention. 
     FIG. 3 is a schematic drawing showing the handle turned to the unlocking vertical position, the movable clamping plate moved along the guide bar according to the present invention. 
     FIG. 4 shows the work clamp clamped on the workpiece and put with the workpiece on a bench saw for cutting. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a work clamp is shown comprising a guide bar  10 , a fixed clamping plate  20  fastened to the guide bar  10 , a movable clamping plate  30  moved on the guide bar  10  relative to the fixed clamping plate  20 , and a control device adapted to control positioning or movement of the movable clamping plate  30  on the guide bar  10 . 
     The guide bar  10  has a fine-toothed face  11  longitudinally disposed at the top side thereof to increase its surface friction force. The fixed clamping plate  20  comprises a through hole  21  fitting the diameter of the guide bar  10 , a press tongue  22  obliquely downwardly extended from a top side of the periphery of the through hole  21  and stopped against the fine-toothed face  11  of the guide bar  10  to hold the fixed clamping plate  20  on the guide bar  10  in position, and a downwardly extended clamping face  23  disposed at the bottom side thereof. The movable clamping plate  30  has a substantially -shaped profile suspended from and driven to move along the guide bar  10 , comprising a plurality of locating elements  31  disposed at the bottom side of the guide bar  10  and adapted to guide movement of the movable clamping plate  30  along the guide bar  10  in horizontal direction, a downwardly extended clamping face  32  disposed at the bottom side thereof corresponding to the clamping face  23  of the fixed clamp plate  20 , and two upright lugs  33  arranged in parallel at the top side thereof. The aforesaid control device is comprised of a handle  40 , a linkage  50 , and a stop plate  60 . The handle  40  has one end terminating in a handgrip  41 , and the other end terminating in a blade  42 . The blade  42  has a front lower corner pivoted to the lugs  33  of the movable clamping plate  30  by a pivot pin  43 , and a front upper corner provided with pivot  44 . The linkage  50  is comprised of two triangular coupling plates  51 , two first links  52 , and a second link  53 . The triangular coupling plates  51  each have a first angle pivoted to the movable clamping plate  30  by a first pivot  511 , a second angle provided with a second pivot  512 , and a third angle provided with a third pivot  513 . The first links  52  each have a first end pivoted to the second pivot  512  of each of the triangular coupling plates  51 , and a second end pivoted to the pivot  44  at the front upper corner of the blade  42  of the handle  40 . The second link  53  is inserted through the inside space of the movable clamping plate  30  having a first end respectively pivoted to the third pivot  513  of each of the triangular coupling plates  51 , and a second end terminating in a first fork  531  and a second fork  532 . The stop plate  60  is sleeved onto the guide bar  10  (the stop plate  60  has an opening for the passing of the guide bar  10 ) and disposed between the fixed clamping plate  20  and the movable clamping plate  30 , having an angled bottom coupling flange  61  coupled to the first fork  531  of the second link  53 , and a press tongue  63  obliquely downwardly disposed at the top and stopped against the fine-toothed face  11  of the guide bar  10  to hold the stop plate  60  on the guide bar  10  in position. The angled bottom coupling flange  61  has a through hole  62 . The first fork  531  of the second link  53  is inserted through the through hole  62  of the angled bottom coupling flange  61 . After insertion of the first fork  531  of the second link  53  through the through hole  62  of the angled bottom coupling flange  61 , a transverse stop rod  533  is fastened to the first fork  531  to secure the second link  53  to the stop plate  60 . 
     Referring to FIG. 2, wooden workpiece  70  are arranged together between the clamping face  23  of the fixed clamping plate  20  and the clamping face  32  of the movable clamping plate  30 , and then the handgrip  41  of the handle  40  is pressed down to turn the pivot  44  and the blade  42  in clockwise direction, thereby causing the first links  52  to move the triangular coupling plates  51  to further force the second link  53  downwards toward the movable clamping plate  30 . The stop rod  533  of the second link  53  is stopped at the angled bottom coupling flange  61  of the stop plate  60  at this time, therefore the stop plate  60  is pulled downwardly backwards to force the top peripheral side of the opening through which the guide bar  10  passes against the teeth of the fine-toothed face  11  of the guide bar  10  to hold down the movable clamping plate  30  in position, thus the clamping faces  23  and  32  are firmly clamped on the workpiece  70 . 
     Referring to FIG.  3 . when releasing the workpiece  70 , the handgrip  41  is lifted, and the pivot  44  with the blade  42  are turned in counter-clockwise direction to move the first links  52  downwards, thereby causing the triangular coupling plates  51  to be turned downwards with the first links  52 , and at the same time the second link  53  is forced upwardly forwards by the triangular coupling plates  51  to disengage the transverse stop rod  533  from the angled bottom coupling flange  61  and to push the second fork  532  against the stop plate  60  thereby causing the press tongue  63  to be disengaged from the fine-toothed face  11  of the guide bar  10  for enabling the movable clamping plate  30  to be moved away from the workpiece  70  along the guide bar  10 . 
     FIG. 4 shows the work clamp clamped on wooden workpiece  70  and put with wooden workpiece  70  on a bench saw  80  for processing. As indicated above, the operation of the work clamp is so simple. When turning the handle  40  downwards to the horizontal position as shown in FIGS. 1,  2  and  4 , the movable clamping plate  30  is forced against the workpiece  70  and locked. On the contrary, when turning the handle  40  upwards from the horizontal position shown in FIGS. 1,  2  and  4  to the vertical position shown in FIG. 3, the movable clamping plate  30  is unlocked and can be moved along the guide bar  10 . 
     A prototype of work clamp has been constructed with the features of FIGS.  1 ˜ 4 . The work clamp functions smoothly to provide all of the features discussed earlier. 
     Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.