Abstract:
A structure of a hacksaw includes a frame which is combined by a fore part and a rear part, an adjustable mechanism under the fore part connected to one end of the blade for adjusting the tilt angle of the blade, a positioning mechanism under the rear part connected to the other end of the blade and for tensioning the blade by a wedge lever. The frame disassembly to quickly adjust the length to serve different lengths of the blade.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to hacksaws and more particularly to a structure of a hacksaw in which is quickly assembled or disassembled. 
     Typical hacksaw  10  (as shown in FIG. 1) comprises a frame  11 , a handle  12  on one end of the frame  11 , a blade  13  having a thru hole  131  adjacent the front end engaged with a lateral pin  141  of a threaded shank  14 , a wing nut  15  fastened a the outer end of the shank  14 , a thru hole  132  adjacent the rear end of the blade  13  engaged with a lateral pin  161  of a projection  16 . The blade  13  is tensed up or loosened up by rotation of the wing nut  15 . The hacksaw  10  further has a graduated portion  17  on the shank  14  to facilitate the blade a certain angle relative to the frame  11 . However, the wing nut  15  may be loosened under the shake of operation. Because the frame  11  is solid and not flexible, it could not serve for different lengths of the blade  13 . 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention has a main object to provide a structure of a hacksaw which is quickly assembled or disassembled without loosening up. 
     Another object of the present invention is to provide a structure of a hacksaw in which the frame is lengthily adjustable to suite different lengths of the blade. 
     Still another object of the present invention is to provide a structure of a hacksaw in which the blade can be adjusted to exact angle. 
     Further object of the present invention is to provide a structure of a hacksaw which can be operated by two hands to increase its working capability. 
     The present invention will become more fully understood by reference to the following detailed description thereof when read in conjunction with the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plane view to show a hacksaw according to a prior art, 
     FIG. 2 is an exploded perspective view to show a hacksaw of the preferred embodiment according to the present invention. 
     FIG. 3 is a perspective view to show the assembly of the hacksaw of FIG. 2, 
     FIG. 4 is a plane view of FIG. 3, 
     FIG. 5 is a sectional view to show the lower part of the hacksaw of the present invention, 
     FIG. 6 is a sectional view a positioning mechanism of the hacksaw of the present invention, 
     FIG. 7 is a sectional view to show that a wedge lever is put down to loosen to blade, 
     FIG. 8 is a sectional view to show an adjustable mechanism of the present invention, 
     FIG. 9 is a sectional view to show that the adjustable mechanism is loosening, 
     FIG. 10 is a side elevational view to show the assembly of the frame of the present invention, and 
     FIG. 11 is a sectional view to show that the lateral rods of the fore frame engage with the inverse L-shaped grooves of the rear frame. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to FIG. 1 to  5  of the drawings, the structure of a hacksaw of the present invention comprises generally a frame  20 , a blade  30 , an adjustable mechanism  40  and a positioning mechanism  50 . 
     The frame  20  is combined with a fore frame  21  and rear frame  22 . The fore frame  21  has a projection  211  projected upward from an arcuate portion, a tube  212  connected with a lower end including an inward flange  2121  at rear end connected to a small pipe in the center of the tube  212  and a plurality of connection rods  213  spacedly projected outward from two lateral sides adjacent the upper end. The rear frame  22  has a pistol-grip handle  221  on rear end, a tube  222  connected to the under side of the handle  221  including an inward flange  2221  at an inwardly arcuated rear end  2222 , an inverse U-shaped groove  223  in the body of the rear frame  22 , a plurality of inverse L-shaped grooves in two lateral side of the body engageable with the connection rods  213  of the fore frame  21 , a projection  225  on the top of the handle  221  facing to the projection  211  of the fore frame  21  at a distance which are provided to facilitate the thumbs of two hands to operate the hacksaw (as shown in FIG.  4 ), and an indentation  226  under the handle  221  including a protrudent member  2261  at outer side. 
     The blade  30  has two eyes  31  and  32  adjacent two ends. 
     The adjustable mechanism  40  has a graduated cap  41  including an internally threaded  412  rectangular block  411  centrally extended outward from the inner surface of the bottom thereof (as shown in FIG.  5 ), a hollow bore cylinder stopper  42  including a rectangular cavity  421  and a central bore disposed between the cap  41  and the small pipe of the tube  212  biased by a spring  43  with the rectangular cavity  421  engaged with the rectangular block  411  of the cap  41  and a threaded shank  44  inserted into the small tube of the tube  212  and the central bore of the hollow cylinder stopper  42  and then fastened to the internal threads  412  of the cap  41 . The shank  44  has a rectangular head  441  and a bevel pin  442  on one lateral side of the rectangular head  441  for engaging with an eye  31  of the blade  30 . The spring  43  which is wrapped on the small pipe has one end reached to the inner surface of the inward flange  2121  and the other end stopped against the peripheral wall of the hollow cylinder stopper  42  which is rotated simultaneously with the cap  41 . 
     The positioning mechanism  50  has a shank  51  including a bevel pin  511  on a lateral side of a rectangular head  512  of the shank  51  for engaging the other eye  32  of the blade  30  and an annular groove  513  adjacent an inner end thereof, a hollow cylinder  52  axially disposed into the fore end of the tube  222  of the rear frame  22  having a rectangular cavity  521  in fore end engaged with the rectangular head  512  of the shank  51  which is inserted into the hollow cylinder  52 , a spring  53  biased between the hollow cylinder  52  and the inner surface of the inward flange  2221  of the tube  222 , a tubular rod  54  having a reduced central bore  541  in fore end engaged within the free end of the shank  51  secured by an elastic C-shaped ring.  56  in the annular groove  513  so that the shank  51  is captured in the tubular rod  54  and an aligned thru hole  542  in a periphery adjacent the rear end thereof. The tubular rod  54  inserted into the rear end of the tube  222  through the spring  53  to give the shank a certain elastic tension. A wedge lever  55  having a eccentric aligned thru hole  551  engaged with the aligned thru hole  542  of the tubular rod  54  and rotatably secured by a pin  552 , a round outer edge  552  on lower end engageable with the inwardly arcuated end  2222  of the tube  222  and a thumbpiece  554  engageable into the indentation  226  and hold by the protrudent member  2261  of the handle  221  (as shown in FIG. 6) in order to prevent any inadvertent touch to the thumbpiece  554 . 
     Referring to FIG. 6 to  9  of the drawing, when disassembles the blade  30 , presses the graduated cap  41  inward (as shown in FIG. 8 and 9) and rotates the wedge lever downward (as shown in FIG. 7) to shorten the eccentric distance so that both the tubular rod  54  and the shank  51  are moving forward. The blade  30  is loose to be removed to change a new one. When assembles a new blade  30 , respectively engages the eyes  31  and  32  onto the bevel pins  442  and  511  and rotates the wedge lever upward (as shown in FIG. 6) to have the eccentric distance elongated. Then the shank  51  and the tubular rod  54  are forced to move rearward to tense the blade  30  without loosening. Both the springs  43  and  53  provide appropriate tension force to the blade  30 . If adjusting the tilt angle of the blade  30 , turns the wedge lever  55  downward (as shown in FIG. 7) and rotates the graduated cap  41 , both the shanks  44  and  51  become rotatable so as to find a certain degree of the tilt angle for the blade  30  relative to the frame  20 . 
     Referring to FIG. 10 and 11 and FIG. 2 again, if fries to change the length of the frame  20  in order to suit to different lengths of the blades  30  that is to change the position of the lateral rods  213  of the fore fame  21  to the suitable inverse L-shaped grooves of the rear frame  22 . This process is very simple and rapid. 
     The specification relating to the above embodiment should be construed as exemplary rather than as limitative of the present invention, with many variations and modifications being readily attainable by a person of average skill in the art without departing from the spirit or scope thereof as defined by the appended claims and their legal equivalents.