Patent Publication Number: US-2011072943-A1

Title: Riving knife adjustment mechanism for a saw machine

Description:
This application claims, under 35 U.S.C. §119, priority to Taiwanese Application No. 098132925, filed Sep. 29, 2009, which application is hereby incorporated by reference in its entirety, inclusive of the specification, claims, and drawings. 
     FIELD OF THE INVENTION 
     The present disclosure relates to saw machines and more specifically, to a riving knife adjustment mechanism for a saw machine. 
     BACKGROUND 
     A saw machine has safety devices to protect the operator from injury. For example, a riving knife is fixedly mounted on the machine base behind the saw blade to prevent a phenomenon known as kickback, which occurs when the wood being cut is caught by the rear edge of the saw blade, lifted off the table and propelled backwards toward the operator. 
     Such safety devices typically require adjustment. In particular, when changing out different sizes of saw blades for cutting different thickness of wooden materials, or different saw blade working conditions, the height of the saw blade may have to be adjusted up and down. In such a case, the riving knife may also have to be adjusted subject to the position of the saw blade. Therefore, it is a desired function of a saw machine to allow quick mounting, dismounting and adjustment of the riving knife. 
     U.S. Pat. No. 6,840,144 B2 discloses a riving knife mounting structure, as reproduced in  FIG. 1 , which includes a control plate  1  having a sloping face  102 , and which is movable to control a spring-loaded pin  2 , causing the spring-loaded pin  2  to engage with a retaining hole  301  on a riving knife  3  or to move away from the retaining hole  301 . Thus, the riving knife  3  can be adjusted vertically or detached from the machine for replacement. 
     Additionally, U.S. Pat. No. 7,437,981 B2, Taiwan Patent No. TW 1305160 and TW M280905 also disclose quick-detachable, quick-adjustable riving knife mounting structures. 
     The structure disclosed in U.S. Pat. No. 6,840,144 B2 (as shown in  FIG. 1 ) allows quick adjustment or replacement of the riving knife  3  on a mounting frame  4 . However, when adjusting or replacing the riving knife  3 , the operator must insert a hand into the inside of the machine base of the saw machine (not shown) to operate the control plate  1  within a narrow space. As such, it is inconvenient to operate this structure. U.S. Pat. No. 7,437,981 B2, Taiwan Patent No. TW 1305160 and TW M280905 also disclose structures that have the same problem. 
     SUMMARY 
     The present disclosure has been accomplished under the circumstances in view. Accordingly, embodiments of the present disclosure provide a riving knife adjustment mechanism for a saw machine, which is easy to operate and allows for quick adjustment. 
     In particular, a riving knife adjustment mechanism is installed in a machine base of a saw machine that has a top wall. The riving knife adjustment mechanism includes a locating member, a riving knife, and a locking unit. The locating member is fixedly mounted in the machine base below the top wall, and defines a track that extends along a longitudinal direction toward the top wall. The riving knife has a coupling portion slidably inserted into the track of the locating member. 
     The coupling portion has at least one first retaining hole and at least one second retaining hole spaced from the at least one first retaining hole in the longitudinal direction. The locking unit comprises a brake pivotally connected to the locating member, and at least one spherical retaining member controllable by the brake to engage the at least one first retaining hole or the at least one second retaining hole of the riving knife, or to move away from the at least one first retaining hole or at least one second retaining hole of the riving knife. 
     In another embodiment, a riving knife adjustment mechanism is installed in a machine base of a saw machine that has a top wall. The riving knife adjustment mechanism includes a locating member, a riving knife and a locking unit. The locating member is fixedly mounted in the machine base below the top wall, and includes a base member, a constraint plate affixed to the base member, and a track defined between the base member and the constraint plate and extending along a longitudinal direction toward the top wall. 
     The constraint plate has at least one through hole in communication with the track. The riving knife has a coupling portion slidably inserted into the track of the locating member. The coupling portion has at least one first retaining hole. The locking unit includes a brake pivotally connected to the constraint plate, and at least one spherical retaining member controllable by the brake to engage through the at least one through hole into the at least one first retaining hole of the riving knife or to move away from the at least one first retaining hole. 
     Operating the brake moves the retaining members into or out of the first or second retaining holes to lock or unlock the riving knife, and therefore the adjustment of the position of the riving knife is quick and simple. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  is an exploded view of a riving knife adjustment mechanism according to the prior art. 
         FIG. 2  is an exploded view of a riving knife adjustment mechanism in accordance with a first embodiment of the present disclosure. 
         FIG. 3  is a plain assembly view of the first embodiment of the present disclosure, showing the riving knife in the topmost position. 
         FIG. 4  is a sectional view taken along line IV-IV of  FIG. 3 . 
         FIG. 5  is a sectional view taken along line V-V of  FIG. 4 . 
         FIG. 6  corresponds to  FIG. 4 , showing the pull knob of the locking unit in a lifted position. 
         FIG. 7  is a schematic operational view of the first embodiment of the present disclosure, showing the riving knife in the lowest position. 
         FIG. 8  is a sectional view taken along line VIII-VIII of  FIG. 7 . 
         FIG. 9  is a sectional view taken along line IX-IX of  FIG. 8 . 
         FIG. 10  is an exploded view of a riving knife adjustment mechanism in accordance with a second embodiment of the present disclosure. 
         FIG. 11  is a plain assembly view of the second embodiment of the present disclosure, showing the riving knife in the topmost position. 
         FIG. 12  is a sectional view taken along line XII-XII of  FIG. 11 . 
         FIG. 13  is a schematic operational view of the second embodiment of the present disclosure, showing the riving knife in the lowest position. 
         FIG. 14  is a sectional view taken along line XIV-XIV of  FIG. 13 . 
     
    
    
     DETAILED DESCRIPTION  
     Other and further technical features, benefits and advantages of the present disclosure will be understood by reference to the description of the following two examples in conjunction with the accompanying drawings, in which like reference characters denote like elements of structure. 
     Referring to  FIGS. 2 ,  3  and  4 , a riving knife adjustment mechanism in accordance with a first embodiment of the present disclosure is shown installed in a machine base  100  that has a top wall  110 . The riving knife adjustment mechanism includes a locating member  10 , a riving knife  20 , and a locking unit  30 . 
     The locating member  10  is affixed to the machine base  100  below the top wall  110 . Further, the locating member  10  includes a base member  11 , a constraint plate  12  affixed to the base member  11 , a plurality of washers  14  set between the base member  11  and the constraint plate  12 , and a track  13  defined by the washers  14  between the base member  11  and the constraint plate  12 . The constraint plate  12  has two through holes  121  disposed in communication with the track  13 , an axle  122  extending along a first axis L 1  between the two through holes  121  and a locating hole  123  disposed at one side relative to the track  13 . The track  13  extends along a longitudinal direction X toward the top wall  110 . 
     The riving knife  20  has a coupling portion  21  slidably inserted into the track  13  in the locating member  10 , and a riving knife body  22  connected to one side of the coupling portion  21  and facing the top wall  110 . The coupling portion  21  has two first retaining holes  211 , and two second retaining holes  212  spaced from the first retaining holes  211  along the longitudinal direction X. 
     The locking unit  30  comprises a brake  31  pivotally connected to the constraint plate  12 , two retaining members  32  controlled by the brake  31 , a spring-loaded locating pin  33  mounted on the brake  31  and a pull knob  34  mounted on the rear end of the spring-loaded locating pin  33 . 
     The brake  31  is mounted on an axle  122  of the constraint plate  12  and is rotatable on the first axis L 1 . The brake  31  includes a bottom wall  311 , two recessed brake portions  312  located on the bottom wall  311  and corresponding to the two through holes  121 , a handle  313  extended from the periphery, and a stepped hole  314  disposed adjacent to the handle  313  at one side thereof. 
     The recessed brake portions  312  are in the form of arc shaped grooves arranged around the first axis L 1 , each having opposing shallow ends  315  and a deep ends  316 . Each deep end  316  of each arc shaped groove has a depth greater than the shallow end  315 . 
     The retaining members  32  are spherical members, for example, steel balls. When the retaining members  32  are respectively moved to the shallow ends  315  of the recessed brake portions  312 , they partially protrude through the through holes  121  and into the first retaining holes  211  or into the second retaining holes  212 . The spring-loaded locating pin  33  is mounted in the stepped hole  314  for engaging the locating hole  123 . 
     Referring to  FIGS. 3 ,  4  and  5 , the riving knife body  22  of the riving knife  20  protrudes over the top wall  110  of the machine base  100  in the topmost position. In this position, the shallow ends  315  of the recessed brake portions  312  of the brake  31  force the retaining members  32  to engage the first retaining holes  211 , and the spring-loaded locating pin  33  is engaged into the locating hole  123  to lock the brake  31 , assuring positive positioning of the riving knife  20 , i.e., the riving knife  20  is locked to the machine base  100  in the topmost position. 
     In order to adjust the position of the riving knife  20  or to detach the riving knife  20  from the locating member  10 , as shown in  FIG. 6 , the pull knob  34  of the locking unit  30  is pulled against the force of the spring to disengage the spring-loaded locating pin  33  from the locating hole  123 . Next the handle  313  is moved to rotate the brake  31  relative to the constraint plate  12 . At this time, as shown in  FIGS. 7 ,  8  and  9 , the shallow ends  315  are moved away from the retaining members  32  and the deep ends  316  are moved toward the retaining members  32 . Subject to the configuration that the depth of the deep ends  316  is greater than the shallow ends  315 , a space is provided in the brake  31  within which the retaining members  32  are movable. At this time, the riving knife  20  can be moved relative to the top wall  110  from the topmost position to the lowest position to disengage the first retaining holes  211  from the retaining members  32  and to move the second retaining holes  212  into alignment with the retaining members  32 , enabling the retaining members  32  to be engaged into the second retaining holes  212 . 
     At this time, the operator can reverse the brake  31  to move the shallow ends  315  of the recessed brake portions  312  to the retaining members  32 , thereby returning to the braking position shown in  FIG. 4 . At this time, the spring-loaded locating pin  33  is automatically biased into the locating hole  123  to lock the brake  31 , and thereafter the riving knife  20  is locked in position. 
     By means of operating the brake  31 , the retaining members  32  are controlled to engage the first retaining holes  211  or second retaining holes  212 , or to move out of the first retaining holes  211  or second retaining holes  212 . Therefore, the operator can adjust the position of the riving knife  20  conveniently. Further, the whole structural configuration of this riving knife adjustment mechanism is quite simple. 
       FIG. 10  illustrates a riving knife adjustment mechanism in accordance with a second embodiment of the present disclosure. Similarly to the first embodiment, the riving knife adjustment mechanism according to this second embodiment also includes a locating member  10 ′, a riving knife  20 ′, and a locking unit  30 ′. 
     The constraint plate  12 ′ of the locating member  10 ′ has two through holes  121 ′ and two lugs  122 ′ disposed at two opposite lateral sides relative to the through holes  121 ′. The locking unit  30 ′ includes two brakes  31 ′ respectively pivotally mounted on the lugs  122 ′ and rotatable about a second axis L 2 , two retaining members, for example, steel balls  32 ′ and two spring members  33 ′ respectively positioned between the brakes  31 ′ and the constraint plate  12 ′. 
     Each brake  31 ′ has a brake portion  312 ′ disposed eccentrically relative to the constraint plate  12 ′ and a pressure plate  313 ′ fixedly connected to the brake portion  312 ′. The brake portion  312 ′ of each brake  31 ′ has a wide section  315 ′ that is spaced from the second axis L 2  at a relatively longer distance, and a narrow section  316 ′ that is spaced from the second axis L 2  at a relatively shorter distance. The spring members  33 ′ are respectively positioned between the pressure plates  313 ′ of the brakes  31 ′ and the constraint plate  12 ′. 
     As shown in  FIGS. 11 and 12 , normally, the spring power of the spring members  33 ′ forces the wide sections  315 ′ of the brakes  31 ′ to stop against the retaining members  32 ′, causing the retaining members  32 ′ to pass through the through holes  121 ′ into the first retaining holes  211 ′ of the riving knife  20 ′. 
     Further, as shown in  FIGS. 13 and 14 , when the pressure plates  313 ′ are pressed to move the brake portions  312 ′ to the position where the narrow sections  316 ′ of the brakes  31 ′ are respectively moved to engage the retaining members  32 ′, the riving knife  20 ′ is unlocked and can be moved relative to the locating member  10 ′. When the riving knife  20 ′ is moved at this time, the retaining members  32 ′ are forced out of the first retaining holes  211 ′ of the riving knife  20 ′. 
     When the riving knife  20 ′ is continuously moved to the position where the second retaining holes  212 ′ are respectively aligned with the retaining members  32 ′, the pressure is released from the pressure plates  313 ′ to enable the wide sections  315 ′ of the brakes  31 ′ to be forced by the spring members  33 ′ against the retaining members  32 ′ to thus move the retaining members  32 ′ into the second retaining holes  212 ′ (i.e., returned to the condition shown in  FIG. 12 ), and thereafter the riving knife  20 ′ is locked in the adjusted position. 
     Although particular embodiments of the disclosure have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the disclosure. Accordingly, the disclosure is not to be limited except as by the appended claims