Abstract:
A protective cover device includes a supporting member secured to a worktable of a sawing machine, a cantilever having rear and front pivot ends pivoted to the supporting member and a cover shield by rear and front journal pins, respectively. At least one of the rear and front journal pins is movable relative to a corresponding one of the rear and front pivot ends between a latched position, where a respective one of the rear and front journal pins pivotally secures a corresponding one of the rear and front pivot ends to a corresponding one of the supporting member and the cover shield, and a released position, where the respective one of the rear and front journal pins is clear of the corresponding one of the supporting member and the front pivot end by being withdrawn therefrom.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a protective cover device, more particularly to a protective cover device adapted to be mounted on a worktable of a sawing machine on which a workpiece is fed so as to cover a cutting blade of the sawing machine. 
   2. Description of the Related Art 
   Referring to  FIG. 1 , a conventional protective cover device  10  is shown to include a supporting member  11 , a cover shield  12 , and a parallel linkage  13 . The supporting member  11  has a lower end  112  secured on a worktable of a sawing machine (not shown). The cover shield  12  defines an accommodation space  121  configured to cover a circular saw blade (not shown) of the sawing machine. The parallel linkage  13  includes two parallel levers  131 ,  132 , each pivoted to the cover shield  12  and an upper end  111  of the supporting member  11  so as to permit turning of the cover shield  12  relative to the supporting member  11 . 
   Although the cover shield  12  can be moved to cover the saw blade for protecting the operator from flying wood shavings during sawing operation, the cover shield  12  is not detachable from the supporting member  11  and may therefore interfere with the replacement of the saw blade. 
   SUMMARY OF THE INVENTION 
   The object of the present invention is to provide a protective cover device which is detachably assembled to a worktable of a sawing machine so as to facilitate replacement of a saw blade on the machine. 
   According to this invention, the protective cover device includes a supporting member having a lower end portion which is adapted to be secured on a worktable of a sawing machine, and an upper end portion which is opposite to the lower end portion in an upright direction and which has a rear pivot hole extending therethrough in a transverse direction. A cantilever has front and rear pivot ends opposite to each other in a longitudinal direction such that a rear journal pin extends into the rear pivot hole to pivotally secure the rear pivot end to the upper end portion. Thus, the rear pivot end is turnable between a lifted position where the front pivot end is remote from the upper end portion, and a working position where the front pivot end is closer to the upper end portion. A cover shield is adapted to cover a cutting blade of the sawing machine, and includes front and rear ends opposite to each other in the longitudinal direction, and a middle portion interposed therebetween. The front end extends downwards to terminate at a nose edge. The middle portion has a front pivot hole extending in the transverse direction such that a front journal pin extends into the front pivot hole and the front pivot end of the cantilever to pivotally secure the middle portion to the front pivot end of the cantilever. Thus, the nose edge is brought to be in sliding contact with an upper surface of a workpiece on the worktable by virtue of gravity when the rear pivot end is in the working position. At least one of the rear and front journal pins is movable relative to a corresponding one of the rear and front pivot ends in the transverse direction between a latched position, where a respective one of the rear and front journal pins pivotally secures a corresponding one of the rear and front pivot ends to a corresponding one of the upper end portion and the middle portion by extending into a corresponding one of the rear and front pivot holes, and a released position, where the respective one of the rear and front journal pins is clear of the corresponding one of the rear pivot hole and the front pivot end by being withdrawn therefrom in the transverse direction. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment of the invention, with reference to the accompanying drawings, in which: 
       FIG. 1  is a schematic view of a conventional protective cover device; 
       FIG. 2  is a perspective view of the preferred embodiment of a protective cover device according to this invention; 
       FIG. 3  is a schematic view of the preferred embodiment; 
       FIG. 4  is an exploded perspective view of the preferred embodiment; 
       FIG. 5  is an exploded perspective view of the preferred embodiment in part; 
       FIG. 6  is a fragmentary assembled sectional view of the preferred embodiment shown in  FIG. 5 , showing a rear journal pin in a latched position; 
       FIG. 7  is a fragmentary sectional view similar to  FIG. 6 , showing how a cantilever is detached from a supporting member; 
       FIG. 8  is a schematic view of the preferred embodiment, showing the cantilever is detached from the supporting member; 
       FIG. 9  is an exploded perspective view of the preferred embodiment in part; 
       FIG. 10  is a fragmentary assembled sectional view of the preferred embodiment shown in  FIG. 9 , showing a front journal pin in a latched position; 
       FIG. 11  is a fragmentary sectional view similar to  FIG. 10 , showing how a cover shield is detached from the cantilever; 
       FIG. 12  is a schematic view of the preferred embodiment showing that the cover shield is detached from the cantilever; 
       FIG. 13  is an exploded perspective view of the preferred embodiment in part; 
       FIG. 14  is a fragmentary assembled sectional view of the preferred embodiment shown in  FIG. 13 , showing a retaining pin in a latched position; 
       FIG. 15  is a fragmentary sectional view similar to  FIG. 14 , showing how two hold-down members are detached from the supporting member; and 
       FIG. 16  is a schematic view of the preferred embodiment, showing that the hold-down members are detached from the supporting member. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 2 to 4 , the preferred embodiment of a protective cover device according to the present invention is adapted to be mounted on a worktable of a sawing machine (not shown) on which a workpiece (not shown) is fed along a working path in a longitudinal direction, and is shown to comprise a supporting member  20 , a cantilever  40 , a cover shield  30 , a rear journal unit  50 , a front journal unit  60 , and a hold-down unit  70 . 
   The supporting member  20  is in the form of a flat plate, and has a lower end portion  21  which is adapted to be secured on the worktable of the sawing machine, and an upper end portion  22  which is opposite to the lower end portion  21  in an upright direction transverse to the longitudinal direction and which has a rear pivot hole  23  and a retaining hole  24  extending therethrough in a transverse direction relative to both the upright direction and the longitudinal direction, and a retaining edge  25  disposed upwardly of the retaining hole  24 . The rear pivot hole  23  is round, and the retaining hole  24  is rectangular. 
   The cantilever  40  has front and rear pivot ends  401 , 402  opposite to each other in the longitudinal direction. With further reference to  FIGS. 5 and 6 , the rear pivot end  402  includes left and right lugs  43 , 44  which are spaced apart from each other in the transverse direction so as to define an accommodation space for receiving the upper end portion  22  of the supporting member  20  therein, and which respectively have left and right through holes  431 , 441 . 
   The rear journal unit  50  includes a first guiding member  51 , a second guiding member  52 , a rear journal pin  53 , a rear push actuator  54 , and a biasing member  55 . The first guiding member  51  includes a left stem  5112  which is configured to pass through the left through hole  431 , which has an inserting bore  5111  extending along a rear axis in the transverse direction to be exposed to the accommodation space between the lugs  43 , 44 , and which has a left outer threaded surface that surrounds the rear axis and that is threadedly engaged with a left tightening member  512 , and a left enlarged head  511  which extends leftwards from the left stem  5112  and outwardly of the left through hole  431 , and which forms, in cooperation with the left stem  5112 , a left surrounding shoulder to abut against the left lug  43  so as to be secured to the left lug  43 . 
   The second guiding member  52  includes a right stem  5212  which is disposed in and which extends rightwards and outwardly of the right through hole  441 , and a right enlarged head  521  which extends leftwards from the right stem  5212  into the accommodation space between the lugs  43 ,  44 , and which forms, in cooperation with the right stem  5212 , a right surrounding shoulder. The right stem  5212  has a right outer threaded surface which surrounds the rear axis and which is threadedly engaged with a right tightening member  522  so as to permit the right surrounding shoulder to be brought to abut against the right lug  44  so as to be secured to the right lug  44 . The right enlarged head  521  has a guiding bore  5211  which extends along the rear axis to communicate with the inserting bore  5111 . 
   The rear journal pin  53  is received in and is guided to move into the inserting bore  5111 , and has an actuated end  531  which can extend through the rear pivot hole  23  to pivotally secure the rear pivot end  402  of the cantilever  40  to the upper end portion  22  of the supporting member  20 , as shown in  FIG. 6 , such that the rear pivot end  402  is turnable about the rear axis between a lifted position where the front pivot end  401  is remote from the upper end portion  22 , and a working position where the front pivot end  401  is closer to the upper end portion  22 . 
   The biasing member  55  is disposed in the inserting bore  5111  between the left enlarged head  511  and the actuated end  531  of the rear journal pin  53  to bias the actuated end  531  to a latched position, where the actuated end  531  extends through the rear pivot hole  23  so as to pivotally secure the rear pivot end  402  to the upper end portion  22 . 
   The rear push actuator  54  has an actuating end  542  which confronts the actuated end  531  of the rear journal pin  53 , and an operated end  541  which extends outwardly of the guiding bore  5211  and which is pushed to move the actuating end  542  in the transverse direction so as to push the actuated end  531  of the rear journal pin  53  along the rear axis against the biasing action of the biasing member  55  to a released position, where the actuated end  531  is clear of the rear pivot hole  23 , thereby permitting separation of the rear pivot end  402  of the cantilever  40  from the upper end portion  22  of the supporting member  20 , as shown in  FIGS. 7 and 8 . 
   Preferably, each of the actuated end  531  of the rear journal pin  53  and the actuating end  542  of the rear push actuator  54  has a round edge so as to facilitate movement of the rear pivot end  402  upwards and away from the upper end portion  22  while the actuated end  531  is kept in contact with the actuating end  542  by the biasing action of the biasing member  55  in the released position. 
   Referring once again to  FIG. 4 , the cover shield  30  is configured to be adapted to cover a cutting blade (not shown) of the sawing machine, and includes two side plates  31  which are spaced apart from each other in the transverse direction to define a mounting space  33  for receiving the cantilever  40  therein, and a top wall  32  interconnecting the side plates  31 . Each of the side plates  31  includes front and rear ends opposite to each other in the longitudinal direction, and a middle portion interposed therebetween. The front end extends downwards to terminate at a nose edge  34 . The middle portion has a front pivot hole  311  which extends therethrough in the transverse direction. Thus, the cover shield  30  is movable by the cantilever  40  so as to be detached from the supporting member  20  when the rear pivot end  402  of the cantilever  40  is separated from the upper end portion  22  of the supporting member  20 , as shown in  FIG. 8 . 
   Further, referring to  FIGS. 9 and 10 , the front pivot end  401  of the cantilever  40  includes two lugs  41  which are spaced apart from each other in the transverse direction, and an upper wall  42  which interconnects the lugs  41 . Each of the lugs  41  has a through hole  411  extending in the transverse direction, and a releasing hole  421  which extends in the upright direction and which is communicated with the through hole  411  by a communicating slot  412  to form an integral opening. 
   The front journal unit  60  includes a front journal pin with two journal shafts  61  and two screw nuts  62 , and two biasing members  63 . Each of the journal shafts  61  has a shank  611  which extends through the respective front pivot hole  311  to pivotally secure the middle portions of the side plats  31  of the cover shield  30  to the front pivot end  401  of the cantilever  40  such that the nose edges  34  of the cover shield  30  are brought to be in sliding contact with an upper surface of the workpiece fed along the working path by virtue of gravity when the rear pivot end  402  is in the working position. The shank  611  terminates at a connecting end  6111  which is threadedly engaged with the respective screw nut  62 . The journal shaft  61  further has an operated end  612  which is opposite to the connecting end  6111  and which is disposed outwardly of the respective side plate  31 . An operated slot  6121  is formed in the operated end  612  to receive a hand tool (not shown) used to fasten the connecting end  6111  and the screw nut  62 . Each of the biasing members  63  is sleeved on the shank  611  of the respective journal shaft  61  between the operated end  612  and the respective side plate  31 . By virtue of the threaded engagement between the screw nut  62  and the connecting end  6111  against the biasing action of the respective biasing member  63 , each screw nut  62  is brought to abut against the respective side plate  31  so as to be retained in the respective through hole  411 , thereby placing the respective journal shaft  61  in a latched position by the biasing action of the respective biasing member  63 , as shown in  FIG. 10 . 
   As shown in  FIG. 11 , when the operated end  612  is pressed against the biasing action of the respective biasing member  63 , the connecting end  6111  and the screw nut  62  are withdrawn inwardly to be clear of the respective through hole  411  so as to be moved to a released position, thereby permitting lifting of the cover shield  30  away from the lugs  41  in the upright direction, as shown in  FIG. 12 . 
   Furthermore, referring to  FIGS. 13 and 14 , the hold-down unit  70  includes a journal body  71 , two hold-down members  72 , a first biasing member  74 , a retaining pin  76 , a second biasing member  77 , and a middle push actuator  78 . 
   The journal body  71  is disposed to ride on the retaining edge  25  of the upper end portion  22  of the supporting member  20  through a slot  711 , and has two tubular journal portions  712  which are disposed at two opposite sides of the upper end portion  22  of the supporting member  20  and which respectively have receiving holes  713  that are aligned with the retaining hole  24  in the transverse direction and that are in the form of screw holes so as to threadedly engage screw bolts  73 . In addition, the journal body  71  is formed with a passage hole  714  that extends in the transverse direction. A barrier shaft  75  extends through the passage hole  714 , and has two ends extending outwardly thereof. 
   Each of the hold-down members  72  has an upper pivot end  722  which is journalled on the respective tubular journal portion  712  through a hole  721 , and a lower holding end  723  which extends downwardly from the upper pivot end  722  and which is configured to be kept in sliding contact with the workpiece sawn by the cutting blade so as to stabilize the sawing operation of the sawing machine. 
   The first biasing member  74  is a torsion spring, and includes an abutting portion  741  abutting against the supporting member  20 , two coiled spring portions  742  respectively surrounding the tubular journal portions  712 , and two hooks  743  respectively abutting against the hold-down members  72  so as to bias the lower holding ends  723  of the hold-down members  72  downwardly toward the worktable. Moreover, the turning of the lower holding ends  723  is limited by abutment of the upper pivot ends  722  against the ends of the barrier shaft  75 . 
   The retaining pin  76  is substantially rectangular in shape, and mates with the retaining hole  24  in the upper end portion  22  of the supporting member  20 . The retaining pin  76  is received in the receiving hole  713  in one of the tubular journal portions  712 , extends in the transverse direction, and is movable relative to the journal body  71  in the transverse direction. The second biasing member  77  is disposed in a seat hole  732  in one of the screw bolts  73 . Thus, the retaining pin  76  is movable between a latched position, as shown in  FIG. 14 , where the retaining pin  76  extends into the retaining hole  24  so as to retain the journal body  71  on the upper end portion  22 , and a released position, as shown in  FIG. 15 , where the retaining pin  76  is clear of the retaining hole  24  when pressed out of the retaining hole  24  in the transverse direction against the biasing action of the second biasing member  77 . 
   The middle push actuator  78  extends through the receiving hole  713  in the other one of the tubular journal portions  712 , and has an actuating end  782  extending to be in contact with an actuated end  761  of the retaining pin  76 , and an operated end  781  extending out of the respective screw bolt  73  through a through hole  733  such that the operated end  781  can be operated to push the retaining pin  76  in the transverse direction against the biasing action of the second biasing member  77  so that the retaining pin  76  is clear of the retaining hole  24 , thereby permitting separation of the journal body  71  from the supporting member  20 , as shown in  FIGS. 15 and 16 . 
   Preferably, each of the actuated end  761  of the retaining pin  76  and the actuating end  782  of the middle push actuator  78  has a round edge so as to facilitate movement of the retaining pin  76  upwards and away from the upper end portion  22  while the actuated end  761  is kept in contact with the actuating end  782  by the biasing action of the second biasing member  77  in the released position. 
   As illustrated, when it is desired to replace the cutting blade of the sawing machine, the cover shield  30  and the cantilever  40  can be detached from the supporting member  20  by separating the rear pivot end  402  of the cantilever  40  from the upper end portion  22  of the supporting member  20 , as shown in  FIGS. 7 and 8 . Alternatively, the cover shield  30  can be detached alone from the supporting member  20  by separating the shanks  611  and the screw nuts  62  from the releasing holes  421  in the front pivot end  401  of the cantilever  40 , as shown in  FIGS. 11 and 12 . Thus, replacement of the cutting blade is convenient to conduct. Moreover, the hold-down unit  70  can be detached from the supporting member  20  by removing the journal body  71  from the retaining hole  24  in the supporting member  20 . 
   While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretations and equivalent arrangements.