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.
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.
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:
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.
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
Thus the blade can cut wood workpiece when it is turning.
When the worm shaft 319 underneath the arbor frame 302 is turned by a hand wheel (not shown), the frame 302 will rotate around pivot shaft 301, which will move the blade arbor 307 up and down.
Through this action, the cutting blade can be adjusted up or down for different cutting operations.
In the mean time, there are two trunnion half moon blocks 201 and 203 which are connected by the connecting arm 202.
These two half moon blocks can rotate on the two female round tracks 101 and 102, and drive the blade arbor 307 in bevel angles (0-45 degree), thus the blade can perform bevel (mitre) cuttings.
In order to equip the blade with a splitter or riving knife, the present invention makes a special support arm 305 which is clamped onto arbor frame 302; its right end (when view as presented in
At the same time, this support arm 305 can rotate around the center of blade arbor 307.
The length of the 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).
As any movements of the support arm 305 are around the center of arbor 307 (which is the same turning center of 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 which can rotate around a shaft, the shaft is fixed on the arbor frame 302 (see
Also the present invention designed a quadrant gear 303, which is bolted onto the half moon trunnion block 201 (see
At the highest arbor position (see
As the rotation radius of riving knife/splitter is much larger (normally 2 times larger) than the rotation radius of blade arbor 307 (see
The present invention's special arrangement solved this problem by following movement: When the arbor frame 302 is rotating clockwise (down), the fixed quadrant gear 303 will make the idle gear 304 rotate clockwise, the idle gear 304 then drives the support arm 305 (with rack teeth) rotate counter-clockwise around arbor center 307.
The simultaneous counter-clockwise rotation of the 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 will be given also when the arbor 307 is moved up.
Therefore, the height difference between riving knife/splitter and the blade top tip will be kept unchanged (see
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
Riving knife 308 is attached to base seat 315 by the combination of a spring pressure plate 306 and three lug bolts 309.
A guide slot b (see
The riving knife is kept tight to the base seat 315 by the pressure applied by the spring pressure plate 306, as well as the pressure from the tightened middle lug bolt 309 (the pressure plate 306 is positioned by the middle lug bolt with a collar 310), as shown by
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
The 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
A secure pin hole a (see
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
As such, when a riving knife is to be changed or removed, an operator can “flick” secure pin 311 away from the pin hole a in the riving knife (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. When a splitter 316 (see
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.