Abstract:
Present invention teaches to build a woodworking table saw where, a splitter/riving knife move with the saw blade in a synchronized manner, with an idle gear engaging in planetary circular action around a fixed quadrant gear and the outer gear teeth portion of a support arm, so that any height adjustment or angle tilting done to the saw blade will result in the same movement of the splitter/riving knife, maintaining the constant linear difference (usually 5 mm) between the saw blade and the splitter/riving knife. In addition, to facilitate the installation, changeover, and/or removal of the splitter/riving knife, a spring pressure plate mechanism is used, along with lug bolts and a spring loaded secure pin device to easily set the splitter/riving knife in a pre-set position without using tools and in shorter time duration.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
     The present invention relates generally to a splitter, also called riving knife system, used on table saw with quick release device for change over of splitter and/or riving knife. 
     Woodworking machines such as table saws typically have a splitter behind the saw blade, to hold cut work pieces from closing and to prevent the accidental “kickback” of work pieces that are thrown back to the operators, which often times result in injury to the operators. 
     Traditionally, most of the splitters are mounted on the work table of the table saw; consequently, there are two main disadvantages: one, the splitter does not maintain a constant distance to the saw blade as the blade is being adjusted for different heights; two, if different splitter is needed (for example, to correspond to different arc radius or thickness of different saw blade), the task for the changeover, removal and/or putting in new splitter is difficult and time-consuming. 
     In a non-through cutting scenario (groove cutting), this type of surface-mounted splitter has to be removed, for the intended groove to be cut. In this case, only a riving knife that is “mounted” to the housing for the saw blade can fit the purpose of the cut. However, the current splitter system on the market requires about 20 minutes or longer to make the change over from splitter to riving knife, and it normally requires proper tools to make the change. Operators, in their attempt to save time, sometimes would forego the installation of riving knife and simply start working on work pieces after splitter is removed, greatly enhancing possibility for the injuries that can be brought about by the “kickback” of work pieces. 
     Also the current riving knife system on the market does not maintain a constant height difference between the saw blade and the riving knife which is very important for effective prevention of kickbacks. Whenever the saw blade is set to different height (to cut different groove, for example), a separate effort to adjust the position of the riving knife is required, after the effort of adjusting the saw blade is done. This time-consuming work also very likely prevent operator from using riving knife for non-through cutting. 
     To reach a better safety standard, the trend in the woodworking industry is to have properly shaped and designed splitter and/or riving knife that move with the blade in a synchronized manner, so that at any adjusted blade position, the splitter/riving knife will stay in certain linear distance relative to the blade (range from 3-8 mm, with 5 mm being the norm) resulting in a constant and safe working condition for the operators. Also, it would be a desirable feature to shorten the time spent on the changeover from splitter to riving knife, and vice versa. Preferably, the market would appreciate a changeover time of less than 30 seconds. The short changeover time will be of greater value, when no tools is needed, as disclosed and taught in present invention. 
     To respond to this market trend and preference, present invention deals with the problems of current splitter/riving knife system on the market, by using a unique multi-gear system to keep the splitter/riving knife at a constant linear difference to the saw blade, and a spring pressure plate mechanism for easy changeover and installation of splitter and riving knife without tools. 
     For the need to put in new splitter or riving knife, or have a changeover from a splitter to a riving knife, present invention disclosed a system of quick release and installation by way of a spring pressure plate with lug nuts securing the riving knife quickly to a pre-determined position. 
     The riving knife will have a guide slot that slides into the middle lug nut, while having two lug nuts adjacent to the outside edge, making the task of alignment for the newly inserted riving knife very simple and intuitive, thus promoting the proper use of the riving knife and greatly enhancing the safety for the operator of such wood working machines. All these operations will require no tools and will usually take less than 10 seconds. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Present invention teaches to build a woodworking table saw, particularly the part of the saw blade that will have a splitter/riving knife that move with the saw blade in a synchronized manner, so that any height adjustment or angle tilting done to the saw blade, for purpose of any cut to be applied to the work piece, will result in the same movement of the splitter/riving knife, maintaining the constant linear distance between blade and splitter/riving knife (usually 5 mm). In the mean time, when riving knife is used for non-through cutting, the system of present invention will keep riving knife being lower than top of blade by certain distance (usually 3 mm). 
     In addition, to facilitate the installation, changeover, and/or removal of the splitter/riving knife, a spring pressure plate mechanism is used, along with lug nuts and a locking bolt to easily remove, set and secure the splitter/riving knife in a pre-set position, without using any tools, while allowing easy removal, correcting the time-consuming tasks of setting or changing the riving knife/splitter in the old system, greatly enhancing the efficiency and safety of the system. 
     Throughout this application, riving knife and splitter are treated as equivalent for purpose of the disclosed invention, unless note otherwise specifically. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate the preferred embodiments of the invention and together with the description, serve to explain the principles of the invention. 
       A brief description of the drawings is as follows: 
         FIG. 1  is the structural perspective view of present invention, showing the multi-gear synchro-moving construction of the riving knife system. 
         FIG. 2  shows the profile view of the present invention, showing working relations of different parts and components 
         FIG. 3  shows the riving knife positioning with blade being set at the highest position. 
         FIG. 4  shows the riving knife positioning with blade being set at the lowest position, and the linear distance and height difference between blade and riving knife remain the same. 
         FIG. 5  is the perspective view of the riving knife quick release structure. 
         FIG. 6  shows the profile view of the riving knife quick release structure showing a spring-loaded pin for securing riving knife by the use of a spring pressure plate, in addition to the three lug bolts locking down the spring plate. 
         FIG. 7  shows a preferred shape of a spring pressure plate. 
         FIGS. 8(   a ) and  8 ( b ) show the side views of the riving knife (a) and splitter (b), with a guide slot and a positioning pin hole shown. 
         FIG. 9  is a cut-off section view of the bottom shape of splitter/riving knife. 
         FIG. 10  is the perspective view of the quick release system mounted onto the base seat of the support arm. 
         FIG. 11  shows the assembled view of a riving knife to the base seat of the support arm pursuant to the disclosure of present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The multi-gear synchro-moving splitter/riving knife system with quick release change over device is made upon a woodworking table saw, constructed and connected into the trunnion and arbor driven structure of a table saw. 
     As shown on  FIG. 1  and  FIG. 2 , a blade arbor (or blade spindle)  307  is supported by an arbor frame  302  which also served as a section worm wheel with teeth. A cutting blade is mounted on the blade arbor  307 . 
     Thus the blade can cut wood workpieces when it is being driven by an electric motion for the desired spinning/turning. 
     A worm shaft  319  underneath said arbor frame  302  is turned by a hand wheel (not shown), causing said arbor frame  302  to rotate around a pivot shaft  301 , which will move the blade arbor  307  up and down. 
     As shown in  FIGS. 1-4 , said worm shaft  319  and said arbor frame  302  are mutually engaged with each other, by the thread on saod worm shaft  310  and the teeth on said arbor frame  302 . 
     Through this arrangement of engagement, the cutting blade can be adjusted up or down for different cutting operations. 
     Two trunnion half moon blocks  201 / 203  rotably resting on two female round tracks  101 / 102 , serve to provide the bevel angle adjustment (between 0-45 degrees) for said blade arbor  307 , enabling the cutting blade to perform bevel (mitre) cuttings. 
     Said trunnion half moon blocks  201  and  203  are connected by a connecting arm  202 , as shown in  FIGS. 1 and 2 . 
     In order to equip the blade with a splitter or riving knife, the present invention provides for a special support arm  305  which is clamped onto said arbor frame  302 ; its right end (when view as presented in  FIG. 2 ) is used for mounting splitter or riving knife on back of cutting blade. 
     This special support arm  305 , along with the arbor frame  302  being clamped together, will allow the rotation of the cutting blade along the center axle as defined by said blade arbor  307 . 
     Said special support arm  305  contains an outer gear teeth portion (on the left side of the special support arm  305 , as viewed on  FIGS. 1 and 2 ) that is generally in a “arc” shape, formed like a cut-out section from a circle, and is in engagement relationship to an idle gear  304 , detailed later. 
     The axle line of said blade arbor  307  will be the center of the radius of the arc for the outer gear teeth of the special support arm  305 . 
     The length of the special support arm  305  and its mounting base for riving knife/splitter are calculated and designed to make sure there is a proper linear distance between blade and riving knife/splitter (usually 5 mm). 
     Movements of the special support arm  305  are around the center of said blade arbor  307  (which is the same turning center of the cutting blade), so the linear distance between riving knife/splitter and blade will remain the same as originally arranged (5 mm), no matter where the blade is adjusted to. 
     This design will meet the safety preference where the linear distance between splitter/riving knife and blades are the same at any position of blade; and it solved the problem of old splitter/riving knife system currently on the market. 
     In addition, the present invention arranged an idle gear  304  with its axle point fixed onto said arbor frame  302 . Said idel gear  304  is in engagement relationship to a fixed quadrant gear  303  and the outer gear teeth portion of said special support arm  305 . Such arrangement caused the idle gear  304  to rotate around said pivot shaft  301  at the contact point with a fix quadrant gear  303  (detailed later), said pivot shaft  301  is fixed on the arbor frame  302  (see  FIG. 2 ). 
     A fixed quadrant gear  303  is bolted onto the half moon trunnion block  201  (see  FIG. 2 ). By having said idle gear  304  engaging said quadrant gear  303  and the outer gear teeth portion of said special support arm  305 , the idle gear  304  will be engaged in a planetary circular action around the arc center of said fixed quadrant gear  303 . 
     The effective radius for the arc formation of the outer gear teeth portion on said support arm  305  will have the same effective radius as the arc formation of the fixed quadrant gear  303 . 
     In actual commercial production and practice, the outer gear teeth portion of said support arm  305  can be made to be an integrated part of said special support arm  305 ; it can also be a separate piece and then joined (by welding, for example) to the special support arm  305 . 
     At the highest arbor position (see  FIG. 3 ), when the arbor frame  302  starts to rotate clockwise around said pivot shaft  301  to lower down the cutting blade, riving knife/splitter will be lowered as well. 
     Traditionally, the rotation radius of riving knife/splitter is much larger (normally 2 times larger) than the rotation radius of a corresponding blade arbor. As a result, the riving knife/splitter is lowered about twice much more than the cutting blade, therefore the height difference between blade top tip and riving knife is changed (to be larger), which obviously is not a desired feature. 
     The present invention&#39;s special arrangement solved this problem by the following movements: When the arbor frame  302  is rotating clockwise (downwards), the fixed quadrant gear  303  will cause the idle gear  304  to rotate clockwise, the idle gear  304  then drives the special support arm  305  (with rack teeth) to rotate counter-clockwise around the center axle of said blade arbor  307 . 
     The simultaneous counter-clockwise rotation of the special support arm  305  causes riving knife/splitter to move up, which will compensate the difference of lowering distance between riving knife/splitter and the blade mentioned above. 
     This compensation works equally in the other direction when the blade arbor  307  is moving up (with simultaneous clock-wise rotation of the special support arm  305 , when the idle gear  304  is rotating counter-clockwise). 
     Therefore, the height difference between riving knife/splitter and the blade top tip will be kept unchanged (see  FIG. 3  and  FIG. 4 ) which meets the market demand, and this function is performed in a synchronized manner that eliminates the needs of any additional manual adjustments when blade position is changed. 
     In the case where the splitter needs to be changed to riving knife for non-through cutting operations, the spring pressure plate mechanism of present invention provides an efficient design to achieve that purpose, which requires no tools and usually takes less than 10 seconds. 
     Reference  FIGS. 5-10  for this portion of the toolless easy-changing and quick release feature. 
     Riving knife  308  is attached to a base seat  315  by the combination of a spring pressure plate  306  and three lug bolts  309 . 
     A guide slot “b” (see  FIG. 8 ) is formed on the riving knife  308 . To install a riving knife  308  to the base seat  315 , said riving knife  308  is inserted to position by lining up the guide slot “b” through the bolts  309  in the middle, with two adjacent lug bolts  309  on the outside edge of riving knife  308 . 
     The riving knife  308  is kept tight to the base seat  315  by the pressure applied by a spring pressure plate  306 , as well as the pressure from the tightened middle lug bolt  309  (the spring pressure plate  306  is positioned by the middle lug bolt with a collar  310 ), as shown by  FIGS. 5 and 6 . As can be seen easily, the gap between the spring pressure plate  306  and the base seat  315  is smaller than that of the thickness of riving knife  308 . 
     The spring pressure plate  306  is formed to provide the resilient power similar to the same principle that a bow provides the resilient force to propel out an arrow. The desired shape of the spring pressure plate  306  is shown in  FIGS. 7 , as an example. 
     Three washer-collars  310 , in conjunction with the three lug bolts  309 , serve both to align the position of the riving knife  308  and keep it from moving sideward. 
     The depth of insertion of riving knife  308  is determined by the guide slot “b” (see  FIG. 8 ) and the position of the upper lug bolt  309 . 
     A secure pin hole “a” (see  FIG. 8 ) is formed on the riving knife  308 , so that a secure pin  311  can be pushed forward by spring  314  into secure pin hole “a” (the secure pin  311  will stay in the pin hole “a” by pressure of the spring  314 ), when riving knife  308  is being inserted into its final position. The secure pin  311  keeps the riving knife  308  in position and prevents the riving knife  308  from being pulled out of the base seat  315 . 
     Said spring-loaded secure pin  311  is part of a safety locking device for the installation of riving knife  308  where a bolt housing  313  is formed to the top side of the base seat  315 . A small knob  312  is mounted on the left end (as viewed from the perspective presented by  FIG. 6 ) of secure pin  311 , and it is used for pulling back the secure pin  311  and locking it inside the housing  313  when inserting and pulling out the riving knife  308 . 
     As such, when a riving knife  308  is to be changed or removed, an operator can “flick” secure pin  311  away from the pin hole “a” in the riving knife  308  (pushing against the resilient force of spring  314 ) and lock the knob  312  in a groove of housing  313 , then easily pull out the riving knife  308 . When a splitter  316  (see  FIG. 8 ) is to be put in, the operator inserts the splitter  316  (see  FIG. 8 ) into the gap between spring plate  306  and base seat  315 , and push the splitter  316  all the way to the bottom until the upper lug bolt  309  reaches the inside closed end of the guiding slot “b”, then release the knob  312 , the secure pin  311  will naturally “click” into the secure pin hole “a” in the splitter  316  by force of spring  314 , the splitter  316  will be secured firmly in position, and ready for use. As the riving knife  308  and splitter  316  are designed with the same bottom guide slots and pin holes, the installation and/or change over (for both splitter or riving knife) will be the same operation and extremely easy without any tools. 
     Finally, the said Multi-Gear Synchro-Moving Riving Knife System With Quick Release Device is very economic in engineering and manufacturing, and it can be used on most of the existing table saws with little added cost which will greatly reduce the accidental injuries to operators.