Abstract:
A foldable miter saw includes a base unit, a worktable, a cutting unit, and a safety device. The cutting unit can be set between a working position where the saw blade and the worktable define therebetween a contained angle within 90°˜45° angle and a folded position where a stoppage signal is provided to power off the driver. The arrangement of the safety device enables a power supply to be cut off from the driver automatically when the cutting unit is moved to the folded position.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention The present invention relates to processing machinery, and more particularly, to a foldable miter saw having a safety device. 
         [0002]    2. Description of the Related Art 
         [0003]    A conventional miter saw (Taiwan Patent 201325776) is known comprising a base unit, a worktable rotatable relative to the base unit, a cutting unit connected to the worktable at one lateral side, and a positioning unit. The base unit comprises a bottom frame, and two foot stands respectively fixedly mounted at two opposite lateral sides of the bottom frame. The positioning unit comprises a screw rod threaded into the worktable. When adjusting the cutting angle of the cutting unit, the operator must loosen the screw rod, and then operate the worktable to rotate the cutting unit relative to the base unit. After moving the cutting unit to the desired angle, the screw rod is again fastened tight. 
         [0004]    Further, in Taiwan Patent 201420239, matching between a sector plate-shaped locking member and a positioning unit allows adjustment of the tilting angle of a saw blade of a cutting unit relative to a top wall of a worktable to achieve the desired cutting angle. The maximum tilting angle of the saw blade relative to the top wall of the worktable is a 45° angle. 
         [0005]    The aforesaid prior art miter saws allow adjustment of the cutting angle, however, when these prior art miter saws are temporarily not in use and need to be stored, they require a large storage space because of their large size. Further, when packaging the miter saws for delivery after fabrication, they require much delivery space, which increases the delivery cost. 
         [0006]    Further, when the aforesaid prior art miter saws are not used and need to be stored, the operator may accidentally trigger the motor drive to rotate the saw blade, thus resulting in accidental harm. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a foldable miter saw having a safety device, which automatically cuts off power supply when it is folded into a folded position, thus achieving a high level of operational safety. 
         [0008]    To achieve this and other objects of the present invention, a foldable miter saw having a safety device comprises a base unit, a worktable, a cutting unit, and a safety device. The base unit comprises a front edge, a rear edge opposite to the front edge, a bottom wall extended from the front edge to the rear edge, and a top wall opposite to the bottom wall. The worktable is rotatably mounted at the base unit, comprising a work surface disposed opposite to the bottom wall and corresponding to the top wall and an axle holder facing toward the rear edge and connected to the work surface. The axle holder comprises an axis disposed in parallel to the work surface and extending from the rear edge toward the front edge. The cutting unit comprises a rotating member axially mounted at the axle holder of the worktable and rotatable relative to the base unit and the worktable, a support arm pivotally connected to the axle holder, a saw blade mounted at the support arm, and a driver mounted at the support arm and adapted for driving the saw blade to rotate. The cutting unit is movable between a working position and a folded position. Wherein, in the working position, a contained angle within 90°˜45° is formed between the saw blade and the work surface of the worktable; in the folded position, the saw blade has an end edge thereof disposed in proximity to the work surface and facing toward the work surface. The safety device faces toward the rear edge of the base unit, and is adapted for cutting power supply from the driver when the cutting unit is set in the folded position. 
         [0009]    Accordingly, the effectiveness of the present invention provides various advantages. Subject to the arrangement of the safety device, the power supply is automatically cut off when the cutting unit is moved to the folded position, thus achieving a high level of operational safety. Therefore, the present invention has the characteristics of simple structure, ease of operation and high level of operational safety. 
         [0010]    Other advantages and features of the present invention will be fully understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference signs denote like components of structure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a top perspective view of a foldable miter saw in a working position in accordance with the present invention. 
           [0012]      FIG. 2  is an exploded view of the foldable miter saw in accordance with the present invention. 
           [0013]      FIG. 3  is a rear perspective view of the present invention, illustrating the foldable miter saw in a working position. 
           [0014]      FIG. 4  is a rear side view, partially exploded, of the foldable miter saw in accordance with the present invention. 
           [0015]      FIG. 5  is a schematic rear view of the present invention, illustrating the sensor located away from the pressing member. 
           [0016]      FIG. 6  is a perspective operational view of the present invention, illustrating the cutting unit moved with the worktable through 45° angle relative to the base unit. 
           [0017]      FIG. 7  is a perspective view of the present invention, illustrating the foldable miter saw in the folded position. 
           [0018]      FIG. 8  is a schematic rear view of the present invention, illustrating the cutting unit folded relative to the base unit and the sensor triggered by the pressing member. 
       
    
    
       [0019]    It should be noted that the drawing figures are not necessarily drawn to scale, but instead are drawn to provide a better understanding of the components thereof, and are not intended to be limiting in scope, but rather to provide exemplary illustrations. It should further be noted that the figures illustrate an exemplary embodiment of the present invention and the components thereof, and in no way limits the structures, configurations and components thereof according to the present disclosure. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    Referring to  FIGS. 1, 2, 3 and 4 , a foldable miter saw having a safety device in accordance with the present invention is shown. The foldable miter saw comprises a base unit  10 , a worktable  20 , a cutting unit  30 , and a safety device  40 . 
         [0021]    The base unit  10  comprises a front edge  11 , a rear edge  12  disposed opposite to the front edge  11 , a bottom wall  13  extended from the front edge  11  to the rear edge  12 , and a top wall  14  disposed opposite to the bottom wall  13 . 
         [0022]    Structurally, the base unit  10  comprises a disk-like bottom frame  15 , and two foot stands  16  radially connected to two opposite lateral sides of the bottom frame  15 . The front edge  11  and the rear edge  12  each are respectively formed along a periphery of the disk-like bottom frame  15  and the foot stands  16 . The top wall  14  is formed on the foot stands  16  at a top side. 
         [0023]    The worktable  20  is rotatably mounted on a top wall of the bottom frame  15  of the base unit  10  between the two foot stands  16 , The worktable  20  has a work surface  21  formed thereon and corresponding to the top wall  14  and opposite to the bottom wall  13 , an axle holder  22  connected to the work surface  21  corresponding to the rear edge  12 , and an operating handle  23  arranged opposite to the axle holder  22  and extended outwardly relative to the work surface  21 . The axle holder  22  comprises an axis L extending from the rear edge  12  toward the front edge  11  in a parallel manner relative to the work surface  21 , an operable locking pin  221 , and a shaft  222  extending along the axis L. Further, the shaft  222  comprises a mounting portion  223  located at a rear end thereof corresponding to the rear edge  12 . The mounting portion  223  has a non-circular cross section disposed perpendicular to the axis L. 
         [0024]    The cutting unit  30  comprises a rotating member  31  axially connected to the axle holder  22  and rotatable relative to the base unit  10  and the worktable  20 , a support arm  32  pivotally connected to the rotating member  31 , a saw blade  33  mounted at the support arm  32 , and a driver  34  mounted at the support arm  32  and adapted for driving the saw blade  33  to rotate. The rotating member  31  is axially mounted on the shaft  222  and rotatable to turn the support arm  32  about the axis L relative to the base unit  10  and the worktable  20 , and equipped with a locking member  311  that extends in parallel to the axis L for locking the rotating member  31  to the axle holder  22 . The rotating member  31  has a plurality of locating holes  312 , 313 , 314  defined therein. The locating holes  312 , 313 , 314  are spaced from one another at predetermined angles. The locating hole, referenced by  314 , is elongated arc-shaped. 
         [0025]    The safety device  40  orients toward the rear edge  12  of the base unit  10 . The safety devices comprises a pressing member  41  positionable relative to the worktable  20  or the base unit  10 , and a sensor  42  connected to the rotating member  31  of the cutting unit  30 . In this embodiment, the pressing member  41  is a plate member fixedly mounted at the shaft  22 . The pressing member  41  has a non-circular positioning hole  411  defined therein for fastening the pressing member  41  to the mounting portion  223  and a plate-like contact portion  412  protruded from the peripheral edge of the pressing member  41 . The sensor  42  can be a micro switch, a limit switch, a toggle switch, or a rocker switch. The sensor  42  comprises a sensing portion  421  adapted for receiving and sensing the pressure from the contact portion  412 . 
         [0026]    Referring to  FIGS. 1-4  again, the miter saw is shown in a working position. In the working position, the driver  34  is suspended above the work surface  21  of the worktable  20 . When the workpiece to be cut is placed on the work surface  21 , a vertical cutting operation is performed by operating the support arm  32  to move the saw blade  33  up and down relative to the rotating member  31 . As illustrated in  FIG. 5 , when the cutting unit  30  is in the working position, the sensor  42  is located away from the pressing member  41 , and the driver  34  is normally electrically conducted. 
         [0027]    Referring to  FIG. 6 , when the operator biases the operating handle  23  to turn the worktable  20  and the cutting unit  30  relative to the base unit  10  for performing a miter cut. When the operator operates the locking member  311  and the operable locking pin  221  for allowing rotation of the rotating member  31  about the axis L relative to the worktable  20 . As shown in  FIGS. 1-6 , the cutting unit  30  is turnable about the axis L leftwards or rightwards, and the operable locking pin  221  is engaged in the middle locating hole  313  or left elongated arc-shaped locating hole  314  such that a predetermined contained angle (normally not less than 40°) is formed between a peripheral edge of the saw blade  33  and the work surface  21 . Further, the driver  34  is suspended above the work surface  21  of the worktable  20  for performing a bevel cut. 
         [0028]    If the miter saw is not to be used and needs to be stored or packed for delivery, the operator can rotate the worktable  20  to turn the cutting unit  30  45° counterclockwise relative to the base unit  10  as shown in  FIG. 6 . Thereafter, as shown in  FIG. 7  and  FIG. 8 , the operator can operate the locking member  311  and the operable locking pin  221 , and then disengage the operable locking pin  221  from the locating hole  313  or  314 . The rotating member  31  is then rotated relative to the axle holder  22  for turning the cutting unit  30  clockwise about the axis L relative to the worktable  20  to the position where the peripheral edge of the saw blade  33  is disposed in proximity to the work surface  21  in a parallel manner. At this time, the cutting unit  30  is in a folded position, and the operable locking pin  221  can then be engaged into the locating hole  312  to lock the cutting unit  30  in this folded position where the driver  34  is disposed in proximity to the bottom wall  13  at a rear side relative to the worktable  20  to face toward the rear edge  12 . The rotating member  31  and the support arm  32  are also disposed at a rear side relative to the worktable  20  in this folded position. 
         [0029]    Referring to  FIG. 8 , when the cutting unit  30  is converted to the folded position, the rotating member  31  of the cutting unit  30  will carry the sensing portion  421  of the sensor  42  into contact with the contact portion  412  of the pressing member  41 , thereby cutting off power supply from the driver  34 . Thus, when the cutting unit  30  is converted from the working position to the folded position, the rotating member  31  of the cutting unit  30  drives the sensor  42  toward engagement with the pressing member  41  to cut off power supply from the driver  34  in order to avoid accidentally actuating the miter saw and thus enhance operational safety. When the cutting unit  30  is converted back to the working position, the rotating member  31  drives the sensor  42  to disengage from contact with the pressing member  41 , such that the power supply of the driver  34  is restored. 
         [0030]    It should also be appreciated that in the above-described embodiment, a contact type safety device is used. However, in actual application, a non-contact type safety device (such as an optical sensor) may be used as a substitute. Further, the mounting position of the safety device is not limited to the aforesaid design of mounting the safety device at the shaft  222  at a rear side relative to the rotating member  31 . Alternatively, the safety device can be mounted at any other location at the cutting unit  30  or the base unit  10 , achieving the same level of safety. 
         [0031]    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.