Abstract:
A table saw includes a table, a saw unit coupled to a substantially inverted U-shaped suspension girder, two supporting devices fixedly fastened to the bottom side of the table to support the suspension girder, and two sliding blocks respectively fastened to the two ends of the suspension girder and respectively coupled to a respective arched guide slot in each of the supporting devices to guide movement of the suspension girder along an arched track to keep the cutting reference point of the saw blade in position so that the saw blade can cut the workpiece accurately.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to tabletop sawing apparatus and more particularly, to a table saw, which enables the saw blade to be lifted, lowered and tilted.  
         [0003]     2. Description of the Related Art  
         [0004]      FIG. 1  shows the relative position between the table  1  and the saw unit  2  in a table saw according to the prior art. The table  1  has an opening  1   a,  and a suspension rod  3  arranged at the bottom side in parallel to the longitudinal axis of the opening  1   a.    
         [0005]     The saw unit  2  comprises a linking mechanism  2   a,  a motor drive  2   b,  and a saw blade  2   c.  The linking mechanism  2   a  is coupled to the suspension rod  3 . The motor drive  2   b  is affixed to the linking mechanism  2   a.  The saw blade  2   c  is fastened to the output shaft of the motor drive  2   b  and deviated from the suspension rod  3 . The saw table comprises an adjustment unit (not shown) adapted to drive the linking mechanism  2   a  and to further move the saw blade  2   c  vertically or to tilt the saw blade  2   c.  For example, the top side of the saw blade  2   c  passes through the opening  1   a  and is kept perpendicular to the top surface  1   b  of the table  1 . At this time, the cutting reference point of the saw blade  2   c  is at the location referenced by A. By means of the indication of the scale system (not shown) at the table  1 , the operator can cut the workpiece accurately subject to the desired size.  
         [0006]     However, there is a distance S between the saw blade  2   c  and the suspension rod  3 . When turning the saw blade  2  about the suspension rod  3  to change the tilting angle of the saw blade  2   c  as shown in  FIG. 2 , the cutting reference point of the saw blade  2   c  is shifted from location A to location B. Under the same scale system, the change of the position of the cutting reference point of the saw blade  2   c  results in a cutting error.  
         [0007]     Further, as shown in  FIG. 3 , the suspension rod  3  must have toughness sufficient to support the saw unit  2 . Normally, the suspension rod  3  used has a diameter about 9.5 mm. When lifting the saw blade  2   c  to the extent that the motor drive  2   b  touches the suspension rod  3 , the saw blade  2   c  reaches the upper limit position. At this time, the distance S 1  between the topmost edge of the saw blade  2   c  and the top surface of the table  1  is equal to the maximum cutting depth of the saw blade  2   c  for the workpiece. However, the diameter of 9.5 mm of the suspension rod  3  shortens the lifting space for the saw blade  2   c.    
         [0008]     Therefore, it is desirable to provide a table saw that eliminates the aforesaid drawbacks.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a table saw, which enables the saw blade to have the same cutting reference point when set perpendicular to the table or in any of a variety of tilted positions.  
         [0010]     It is another object of the present invention to provide a table saw, which enables the saw blade to have a greater cutting depth for cutting different workpieces.  
         [0011]     To achieve these objects of the present invention, the table saw comprises a machine base having a side panel and an arched slot formed in the side panel; a table provided at a top side of the machine base and provided with a front side, a rear side, and an opening cut through top and bottom walls thereof; two supporting devices respectively fixedly fastened to the bottom wall of the table near the front side and the rear side of the table, the supporting devices each having a smoothly arched guide slot; a suspension girder coupled between the supporting devices, the suspension girder comprising two sliding blocks respectively disposed at two ends thereof and respectively coupled to the smoothly arched guide slots of the supporting devices; a lifter pivoted to the suspension girder and movable to and fro relative to the suspension girder; a saw unit fixedly fastened to the lifter, the saw unit comprising a saw blade insertable through the opening of the table; and an adjustment unit having a hand wheel disposed outside the side panel of the machine base, and an adjustment rod inserted through the arched slot of the machine base and coupled between the hand wheel and the lifter for moving the lifter relative to the suspension girder upon rotation of the hand wheel. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a schematic drawing of a part of a conventional table saw, showing the saw blade set in vertical relative to the table.  
         [0013]      FIG. 2  corresponds to  FIG. 1 , showing the saw blade tilted.  
         [0014]      FIG. 3  is a schematic drawing of the prior art table saw, showing the saw blade lifted.  
         [0015]      FIG. 4  is an exploded view of a table saw according to the present invention.  
         [0016]      FIG. 5  is an exploded view of a part of  FIG. 4 .  
         [0017]      FIG. 6  is a perspective assembly view of a part of the table saw according to the present invention.  
         [0018]      FIG. 7  is a schematic front view of the table saw according to the present invention.  
         [0019]      FIG. 8  is a sectional view of the present invention, showing the saw blade received below the table of the table saw.  
         [0020]      FIG. 9  is a schematic sectional view of the present invention, showing the saw blade protruded over the table of the table saw.  
         [0021]      FIG. 10  is a schematic drawing of a part of the table saw, showing the saw blade set perpendicular to the top surface of the table according to the present invention.  
         [0022]      FIG. 11  is a schematic drawing of a part of the table saw, showing the saw blade tilted relative to the table according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]     Referring to  FIGS. 4-7 , a table saw  100  in accordance with the present invention is shown comprising a machine base  10 , a table  14 , two supporting devices  18 , four screws  22 , a suspension girder  24 , a lifter  26 , a pin  27 , a saw unit  28 , and an adjustment unit  30 .  
         [0024]     The machine base  10  has a side panel  10   a,  an arched slot  11  formed in the side panel  10   a,  an arched rack  12  extending along one side of the arched slot  11 , and angle-indication graduations  13  arranged in parallel to the arched rack  12 .  
         [0025]     The table  14  is provided at the top side of the machine base  10 , having a front side  141 , a rear side  142 , an opening  143  cut through the top and bottom walls thereof, and two mounting devices  15  and  16 . The mounting devices  15  and  16  are respectively formed in the bottom wall near the front side  141  and the rear side  142 . According to this embodiment, each mounting device  15  or  16  is comprised of two screw holes  151  or  161 .  
         [0026]     The two supporting devices  18  each are comprised of a locating plate  19  and a guide plate  20 . The locating plate  19  comprises a horizontal wall  191  and a vertical wall  192 . The horizontal wall  191  has mounting means formed of two through holes  191   a.  The vertical wall  192  has a smoothly arched slot  192   a.  The guide plate  20  is molded from plastics, having a smoothly arched guide slot  201 . The guide plate  20  is attached to the respective locating plate  19 , keeping the smoothly arched guide slot  201  in communication with the smoothly arched slot  192   a  of the respective locating plate  19 .  
         [0027]     The four screws  22  are respectively inserted through the through holes  191   a  of the horizontal wall  191  of the locating frame  19  of each of the two supporting devices  18  and threaded into the screw holes  151  and  161  of the table  14  to affix the two locating frames  19  to the bottom wall of the table  14 .  
         [0028]     The suspension girder  24  comprises a horizontally extending flat girder base  241 , two vertical side plates  242  and  243  respectively downwardly extending from the two distal ends of the horizontally extending flat girder base  241 , two sliding blocks  244 , two wings  245 , and an inner plate  246 . The sliding blocks  244  are respectively inserted through the smoothly arched slot  192   a  of the vertical wall  192  of the locating plate  19  of each of the supporting devices  18  and the smoothly arched guide slot  201  of the guide plate  20  of each of the supporting devices  18 , having a stop face  244   a  stopped at one side of the respective smoothly arched slot  192   a  and two through holes  244   b  formed in the stop face  244   a  near two distal ends. Screws  247  are respectively inserted through the through holes  244   b  of the sliding blocks  244  and threaded into the two vertical side plates  242  and  243  of the suspension girder  24  to secure the suspension girder  24  to the supporting devices  18 . One vertical side plate  242  of the suspension girder  24  has a locating hole  242   a.  The two wings  245  are fixedly fastened to and vertically downwardly extending from the bottom side of the horizontally extending flat girder base  241 , each having connecting means, for example, a circular hole  245   a.  The inner plate  246  is arranged in parallel to the vertical side plate  242 , having a locating hole  246   a.    
         [0029]     Referring to  FIG. 8  and  FIG. 4  again, the lifter  26  comprises a base frame  261 , which supports the saw unit  28 , and two side frames  262  arranged in parallel at two ends of the base frame  261 . The side frames  262  each have a through hole  262   a  and an elongated slot  262   b.    
         [0030]     The pin  27  is inserted through the circular holes  245   a  of the wings  245  and the through holes  262   a  of the side frames  262  to pivotally secure the lifter  26  to the suspension girder  24  between the wings  245 .  
         [0031]     The saw unit  28  comprises a motor drive  281 , and a saw blade  282 . The motor drive  281  is mounted on the base frame  261  of the lifter  26 , and adapted to rotate the saw blade  282 .  
         [0032]     The adjustment unit  30  comprises a hand wheel  301 , a driven rod  302 , an adjustment rod  303 , a spring  304 , and a pointer  305 .  
         [0033]     The hand wheel  301  is provided outside the side panel  10   a  of the machine base  10 , having a gear  301   a  and a connecting portion  301   b.    
         [0034]     The driven rod  302  is inserted with the two distal ends thereof into the elongated slots  262   b  of the side frames  262  of the lifter  26 , having a transversely extending screw hole  302   a.    
         [0035]     The adjustment rod  303  has a threaded shank  303   a  and a connecting portion  303   b  at one end of the threaded shank  303   a.  The spring  304  is set between the hand wheel  301  and one vertical side plate  242  of the suspension girder  24 , and adapted to force the connecting portion  303   b  of the adjustment rod  303  into engagement with the connecting portion  301   b  of the hand wheel  301  when the hand wheel  301  receives no pressure (see  FIG. 8 ). The threaded shank  303   a  of the adjustment rod  303  is inserted through the spring  304 , the arched slot  11  of the side panel  10   a  of the machine base  10 , the locating hole  242   a  of the suspension girder  24 , and the transversely extending screw hole  302   a  of the driven rod  302  into the locating hole  246   a  of the inner plate  246 . When driving the hand wheel  301  to rotate the adjustment rod  303 , the driven rod  302  is driven by the adjustment rod  303  to change its position so as to lift and lower the saw blade  282 .  FIG. 8  shows the saw blade  282  received below the table  14 .  FIGS. 9 and 10  show the saw blade  282  protruding over the table  14 .  
         [0036]     The pointer  305  is connected to the suspension girder  24  through a connector  306 . When pressed the hand wheel  301  to disengage the connecting portion  301   b  from the connecting portion  303   b  of the adjustment rod  303 , the gear  301   a  is forced into engagement with the arched rack  12 . At this time, the user can rotate the hand wheel  301  to tile the saw blade  282  (see  FIG. 11 ), and the tilting angle of the saw blade  282  is known by means of the indication of the pointer  305  at the angle-indication graduations  13 .  
         [0037]     Referring to  FIG. 11 , the table  14  has a horizontal axis H and a vertical axis V. The horizontal axis H extends along the top surface of the table  14 . The vertical axis V passes through the opening  143  and intersected with the horizontal axis H. The intersected point between the horizontal axis H and the vertical axis V is referenced to be the center point C. When lifting the saw blade  282 , it passes through the center point C, and the two sliding blocks  244  are moved along a circular track of which the center coincides with the center point C. When the saw blade  282  is set perpendicular to the top surface of the table  14 , the cutting reference point of the saw blade  282  is at the center point C. When tilting the saw blade  282 , the saw blade  282  is turned about the center point C, i.e., the cutting reference point of the saw blade  282  remains unchanged for accurate cutting operation when setting the saw blade  282  is any of a variety of angular positions.  
         [0038]     Further, the horizontally extending flat girder base  241  of the suspension girder  24  is close to the bottom side of the table  14  (see  FIG. 10 ). The distance between the horizontally extending flat girder base  241  of the suspension girder  24  and the bottom side of the table  14  is smaller than the diameter (9.5 mm) of the prior art suspension rod  3  shown in  FIG. 3 . Therefore, when lifting the saw blade  282 , a comparatively greater space is available for upward displacement of the motor drive  281 . When lifted the saw blade  282  to the upper limit position, the distance S 2  between the topmost edge of the saw blade  282  and the top surface of the table  1  is greater than the distance S 1  between the topmost edge of the prior art saw blade  2   c  and the top surface of the prior art table  1 , i.e., the saw blade  282  can cut into the workpiece comparatively deeper.  
         [0039]     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.