Patent Abstract:
An apparatus for cutting materials and more specifically an improved saw blade includes a plurality of variable teeth thereon. The variable tooth saw blade cuts faster and smoother while reducing harmonic vibrations. Specifically, the teeth on the saw blade are grouped into sections with differing circumferential widths and differing spacing between the sections.

Full Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a divisional application of U.S. patent application Ser. No. 10/391,425 filed Mar. 18, 2003 now U.S. Pat. No. 7,013,784, which claims priority from U.S. Provisional application Ser. No. 60/365,999 filed Mar. 19, 2002; the disclosures of which are incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Technical Field 
   This invention relates to rotary saw blades, and more particularly circular saw blades for use on circular saws or the like. Specifically, the invention is directed to a variable tooth saw blade that cuts faster and smoother while reducing harmonic vibrations. 
   2. Background Information 
   Circular saw blades are readily available for use in cutting wood and other materials using a portable, hand-held circular saw, or a fixed table or radial saws, or other like saws. The saw blades are formed of flat, circular discs made of steel or other like metals. As is well known in the art, circular saw blades include a peripheral edge from which a plurality of circumferentially-spaced teeth project radially outwardly for cutting. 
   Users continually desire to purchase blades that allow for faster cutting without negative effects such as “burning” of the blade, dulling of the teeth, or jamming of the saw. The ability of the teeth to efficiently cut the material and thus maintain the blade speed is critical. As a result, users continue to desire improved blades providing for faster and/or more efficient cutting. 
   Users also desire smooth cuts. Often the speed of a cut is inversely correlated to the smoothness of the cut, that is, the faster the user cuts, the rougher is the end cut, and vice versa. As a result, users continue to desire improved smoothness coupled with faster cutting. 
   Users further desire reduced noise. The high speed at which blades rotate often causes high levels of harmonic vibration leading to excessive noise, undesirable saw or saw blade vibration, and if the vibration is significant, a less than desirable cut. Users thus desire, and often government agencies require, blades providing for reduced noise and thus reduced harmonic vibration. 
   Consequently, there is a need for an improved saw that cuts faster and smoother while also reducing noise and harmonic vibration. 
   SUMMARY OF THE INVENTION 
   The present invention provides a saw blade comprising a flat, circular disc having a peripheral outer edge and a center hole; a plurality of circumferentially-spaced teeth each having a cutting edge and projecting radially outwardly from the peripheral outer edge; a first group of the cutting edges defining a first circumferential width between each adjacent pair of the cutting edges in the first group; a second group of the cutting edges defining a second circumferential width between each adjacent pair of the cutting edges in the second group; the second circumferential width differing from the first circumferential width; and a third group having at least one cutting edge defining a third circumferential width as one of the distance between adjacent cutting edges in the third group and, the distance between the at least one cutting edge in the third group and the adjacent cutting edge in the adjacent group; the third circumferential width differing from the first and second circumferential widths. 
   The invention further provides a saw blade comprising a flat, circular disc having a peripheral outer edge and a center hole, the disc being divided into a first half and a second half, each half being a copy exact of the other half positioned in a diametrically opposite manner; a plurality of circumferentially-spaced teeth each having a cutting edge and projecting radially outwardly from the peripheral outer edge; a first group in each half having five cutting edges including a first cutting edge and a last cutting edge defining therebetween a first group circumferential width of approximately sixty degrees; a second group in each half having three cutting edges including a first cutting edge and a last cutting edge defining therebetween a second group circumferential width of approximately forty degrees; a third group in each half having one cutting edge and having a third group circumferential width defined between the one cutting edge of the third group and the last cutting edge of the second group, the third group circumferential width being approximately thirty-six degrees; a first circumferential space being between the first and second groups in each half and having an approximately twenty-degree circumferential width; and a second circumferential space being between the third group in each half and the first group in the respective other half and having an approximately twenty-four-degree circumferential width. 
   The invention further provides a saw blade comprising a flat, circular disc having a peripheral outer edge and a center hole, the disc being divided into a first half and a second half, each half being a copy exact of the other half positioned in a diametrically opposite manner; a plurality of circumferentially-spaced teeth each having a cutting edge and projecting radially outwardly from the peripheral outer edge; a first group in each half having seven cutting edges including a first cutting edge and a last cutting edge defining a first group circumferential width therebetween which is approximately thirty-six degrees; a second group in each half having six cutting edges including a first cutting edge and a last cutting edge defining a second group circumferential width therebetween which is approximately forty-five degrees; a third group in each half having three cutting edges including a first cutting edge and a last cutting edge defining a second group circumferential width therebetween which is approximately thirty degrees; a fourth group in each half having two cutting edges defining a second group circumferential width therebetween which is approximately twenty degrees; a first circumferential space being between the first and second groups in each half and having an approximately nine-degree circumferential width; a second circumferential space being between the second and third groups in each half and having an approximately ten-degree circumferential width; a third circumferential space being between the third and fourth groups in each half and having an approximately ten-degree circumferential width; and a fourth circumferential space being between the fourth group in each half and the first group in the respective other half and having an approximately twenty-degree circumferential width. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the invention, illustrative of the best modes in which the applicant has contemplated applying the principles, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims. 
       FIG. 1  is a side view of a first embodiment of the saw blade of the present invention; 
       FIG. 2  is the same side view of the first embodiment of the saw blade as in  FIG. 1  with the sections clearly marked; 
       FIG. 3  is an enlarged view of a few teeth from the saw blade of the first embodiment in  FIGS. 1–2 ; 
       FIG. 4  is a side view of a second embodiment of the saw blade of the present invention; 
       FIG. 5  is the same side view of the second embodiment of the saw blade as in  FIG. 4  with the sections clearly marked; and 
       FIG. 6  is an enlarged view of a few teeth from the saw blade of the second embodiment in  FIGS. 4–5 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The improved saw blade of the present invention is shown in two embodiments in the Figures although other embodiments are contemplated as is apparent to one of skill in the art. Specifically, the first embodiment of the improved saw blade is indicated generally at  20  as shown in  FIGS. 1–2 , while a second embodiment of the improved saw blade is indicated generally at  120  as shown in  FIGS. 4–5 . 
   The first embodiment is saw blade  20  embodied as a standard seven and one quarter inch diameter saw blade although it may be of any other diameter used or contemplated by those of skill in the art. The saw blade whether embodied as blade  20  or  120  is a flat, circular disc  22 , made of steel or other like metals, with a center arbor hole  24  as is well known in the art. The disc  22  includes a peripheral edge  30  with a plurality of circumferentially-spaced teeth projecting radially outwardly therefrom for cutting and generally referred to as  32 . Each tooth  32  has a cutting edge  44  and is more fully described below. 
   In accordance with one of the features of the invention, the blade is divided into an even number of groups or sections, and in more detail the blade  20  in the first embodiment is divided into two halves of six sections while the blade  120  in the second embodiment is divided into two halves of eight sections. Each section along the peripheral edge has a matching or copy exact section diametrically opposite thereto such that a symmetry-like line divides the blade into two halves of a repeating pattern. 
   In further accordance with one of the features of the invention, the sections in each half do not have the same number of teeth or teeth of the same size as the other sections. More particularly, there are a different number of cutting edges  44  in each section in each half and the circumferential width between each of the adjacent cutting edges  44  within a given section is different than that of each other section in a given half. 
   Preferably in accordance with another feature of the invention, the size of the teeth remains the same and/or decreases in each section from a largest size to a smallest size in the direction of cutting (or vice versa), while the number of teeth increases or remains the same in each section in the direction of cutting (or vice versa respectively). More particularly, the circumferential width between each adjacent pair of cutting edges  44  remains the same and/or decreases in each section from largest to smallest in the direction of cutting (or vice versa), while the number of cutting edges  44  increases or remains the same in each section in the direction of cutting (or vice versa respectively). 
   Each tooth  32  includes a tooth body  40  defined as a sloped face or land  42  culminating in outwardly extending cutting edge  44 . On the opposite side of cutting edge  44  from land  42  is a notch or void  54  which communicates with the land  42  of an adjacent tooth  32 . Notch  54  thus separates the cutting edge  44  of one tooth  32  from the land  42  of an adjacent tooth  32 . More specifically, notch  54  includes a radial face  46  extending inwardly toward hole  24  adjacent cutting edge  44  of one tooth  32  into a bend  56  which communicates with land  42  of an adjacent tooth  32 . Land  42  may include an optional additional cutting or finishing edge  52  in the middle thereof for reducing kick-back and providing smoother cuts, whereby such land  42  in the embodiment shown includes a first steep tapered section  48  and a second slightly tapered section  50  separated by the additional cutting edge  52  although other configurations are contemplated including only one tapered section of a constant taper or a gradually changing taper. Specifically, land  42  may be any form of a surface behind tooth  32  that transitions into notch  54 . Cutting edge  44  may be a sharpened edge, or, as in the embodiments, an L-shaped seat  60  in which an insert such as a carbide or diamond tip  62  is seated and secured. The insert has a cutting face  64 . Where an insert is used, cutting edge  64  becomes the cutting edge of a tooth  32  and thus the term “cutting edge” includes “cutting face” in that scenario. 
   In accordance with yet another feature of the invention, the hook angle a of each tooth is most preferably between 15° (fifteen degrees) and 25° (twenty-five degrees). The hook angle a is specifically the angle between the tangent to the cutting face  44  and a radius line through hole  24 . 
   In more detail as to the first embodiment of the blade referred to as  20 , teeth  32  are arranged in a unique eighteen-tooth design that is divided into two copy exact sections, namely a first side  70 A and a second side  70 B divided by axis  72 . Since the blade as shown in  FIGS. 1–2  has a right and left copy exact side (sides  70 A and  70 B respectively), only the right side will be described below (except where necessary to refer to the other or left side where transitions occur). The first side  70 A includes nine teeth, namely teeth  32 A,  32 B,  32 C,  32 D,  32 E,  32 F,  32 G,  32 H, and  32 I separated by voids  54 . 
   In accordance with another feature of the invention, the nine teeth  32 A,  32 B,  32 C,  32 D,  32 E,  32 F,  32 G,  32 H, and  32 I of each side  70 A and  70 B are not all identical in size and spacing. Specifically in the embodiment shown, first side  70 A is divided into three sections  80 ,  82  and  84  (and thus the saw blade  20  has six sections over sides  70 A and  70 B) of varying circumferential distance with differing number of teeth and size of teeth in each. 
   Section  80  includes cutting edges  44  of five teeth  32 , namely teeth  32 A,  32 B,  32 C,  32 D, and  32 E, and these cutting edges define a first circumferential width between each adjacent pair of the cutting edges. Section  80  also includes the trailing components of four teeth  32 , namely teeth  32 B,  32 C,  32 D, and  32 E, so that those four teeth are fully within section  80 , and those teeth within section  80  are substantially identical to one another. These trailing components include land  42  having tapered sections  48  and  50 , and optional additional cutting edge  52 . Thereafter, section  82  includes cutting edges  44  of three teeth, namely teeth  32 F,  32 G and  32 H, and these cutting edges define a second circumferential width between each adjacent pair of the cutting edges that is different from the first circumferential width. Section  82  also includes the trailing components of two teeth, namely teeth  32 G and  32 H, so that those two teeth are fully within section  82 , and those teeth within section  82  are substantially identical to one another. Further thereafter, section  84  includes cutting edge  44  of one tooth, namely tooth  32 I, along with its trailing components, so that tooth  32 I is fully within section  84 . 
   Each of sections  80 ,  82  and  84  is specifically measured as the circumferential group width from the cutting edge  44  of the first tooth  32  of a section to the cutting edge  44  of the last tooth in the same section except where a section has only one tooth  32  and thus its circumferential group width is defined from the cutting edge  44  of the last tooth  32  of the previous section to the cutting edge  44  of the only tooth  32  in the section. Specifically, section  80  is the circumferential group width from the cutting edge  44  of the first tooth  32 A of the section  80  to the cutting edge  44  of the last tooth  32 E in the same section  80 , which is defined as angle b. Section  82  is the circumferential group width from the cutting edge  44  of the first tooth  32 F of the section  82  to the cutting edge  44  of the last tooth  32 H in the same section  82 , which is defined as angle c. Section  84  with only one tooth is the circumferential group width from the cutting edge  44  of the last tooth  32 H of the previous section  82  to the only cutting edge  44  of the only tooth  32 I in the section  84 , which is defined as angle d. The previous section for the first section is the last section, which would mean the last section of the other side where the blade has two copy exact sides, or simply the last section in the case where the sections span the entire circumference of the blade. For example, the section previous to section  80  of side  70 A is section  84  of side  70 B. 
   In between each of the sections are transitions or circumferential spaces  90 ,  92 , and  94 . Specifically, transition  90  is the space between sections  80  and  82 , transition  92  is the space between sections  82  and  84  but since the section  84  has only one tooth then no transition exists as section  84  and transition  92  have the same definition, and transition  94  is the space between sections  84  and  80  of the next side (the left side). This space is defined as the circumferential width from the cutting edge  44  of the last tooth of a section to the cutting edge  44  of the first tooth in the next section. Specifically, transition  90  is the circumferential width from the cutting edge  44  of the tooth  32 E of section  80  to the cutting edge  44  of the tooth  32 F in the next section  82 , which is defined as angle e. Transition  92  does not exist due to the one-tooth nature of section  84 . Transition  94  is the circumferential width from the cutting edge  44  of the tooth  32 I of section  84  to the cutting edge  44  of the tooth  32 A in the next section  80  (which is on the other side or left side in this case), which is defined as angle f. 
   In accordance with one of the features of the invention, the section angle b is 60°, the section angle c is 40°, the section angle d is 36°, the transition angle e is 20°, and the transition angle f is 24°. The effect is a design where section  80  has cutting edges  44  for five teeth, section  82  has cutting edges  44  for three teeth, and section  84  has cutting edges for one tooth, with uneven transitions between sections  80  and  82 , and between  84  and  80  of the other side (the left side). Although it is noted above that no transition  92  exists between sections  82  and  84  because the definition of transition  92  is the same as section  84 , nonetheless, it is also seen that what might be considered as transition  92  also differs from either of transitions  90  and  94 . 
   In more detail as to the second embodiment of the blade referred to as  120 , teeth  32  are arranged in a unique thirty-six tooth design that is divided into two copy exact sections, namely a first side  170 A and a second side  170 B by axis  172 . Since the blade as shown in  FIGS. 4–5  has a right and left copy exact side (sides  170 A and  170 B respectively), only the right side will be described below (except where necessary to refer to the left side). The first side  170 A includes eighteen teeth, namely teeth  132 A,  132 B,  132 C,  132 D,  132 E,  132 F,  132 G,  132 H,  132 I,  132 J,  132 K,  132 L,  132 M,  132 N,  132 O,  132 P,  132 Q, and  132 R. 
   As with the first embodiment and in accordance with one of the features of the invention, the eighteen teeth  132 A,  132 B,  132 C,  132 D,  132 E,  132 F,  132 G,  132 H,  132 I,  132 J,  132 K,  132 L,  132 M,  132 N,  132 O,  132 P,  132 Q, and  132 R of each side  170 A and  170 B are not all identical in size and spacing. Specifically in the embodiment shown, first side  170 A is divided into four sections  180 ,  182 ,  184  and  186  (and thus saw blade  120  has eight sections) of varying circumferential distance with differing number of teeth and size of teeth in each. Section  180  includes cutting edges  44  of seven teeth, namely teeth  132 A,  132 B,  132 C,  132 D,  132 E,  132 F, and  132 G, and these cutting edges define a first circumferential width between each adjacent pair of the cutting edges; Section  180  also includes the trailing components of six teeth, namely teeth  132 B,  132 C,  132 D,  132 E,  132 F and  132 G, so that those six teeth are fully within section  180 , and those teeth within section  180  are substantially identical to one another. As noted above, the trailing components include land  42  including tapered sections  48  and  50 , and optional additional cutting edge  52 . Thereafter, section  182  includes cutting edges  44  of six teeth, namely teeth  132 H,  132 I,  132 J,  132 K,  132 L and  132 M, and these cutting edges define a second circumferential width between each adjacent pair of the cutting edges that is different from the first circumferential width; Section  182  also includes the trailing components of five teeth, namely teeth  132 I,  132 J,  132 K,  132 L and  132 M, so that those five teeth are fully within section  182 , and those teeth within section  182  are substantially identical to one another. Further thereafter, section  184  includes cutting edges  44  of three teeth, namely teeth  132 N,  132 O and  132 P, and these cutting edges define a third circumferential width between each adjacent pair of the cutting edges that is different from the first and second circumferential widths. Section  184  also includes the trailing components of two teeth, namely teeth  132 O and  132 P, so that those two teeth are fully within section  184 , and those teeth within section  184  are substantially identical to one another. Finally thereafter, section  186  includes cutting edges  44  of two teeth, namely teeth  132 Q and  132 R, along with the trailing components of tooth  132 R, so that tooth  132 R is fully within section  186 . 
   In the same manner as described above with reference to the first embodiment, each section is specifically measured as the group circumferential width from the cutting edge  44  of the first tooth of a section to the cutting edge  44  of the last tooth in the same section except where a section has only one tooth  132  and thus its group circumferential width is defined from the cutting edge  44  of the last tooth  132  of the previous section to the cutting edge  44  of the only tooth  132  in the section. Specifically, section  180  is the group circumferential width from the cutting edge  44  of the first tooth  132 A of the section  180  to the cutting edge  44  of the last tooth  132 G in the same section  180 , which is defined as angle g. Section  182  is the group circumferential width from the cutting edge  44  of the first tooth  132 H of the section  182  to the cutting edge  44  of the last tooth  132 M in the same section  182 , which is defined as angle h. Section  184  is the group circumferential width from the cutting edge  44  of the first tooth  132 N of the section  184  to the cutting edge  44  of the last tooth  132 P in the same section  184 , which is defined as angle j. Section  186  is the group circumferential width from the cutting edge  44  of the first tooth  132 Q of the section  186  to the cutting edge  44  of the last tooth  132 R in the same section  186 , which is defined as angle k. 
   In between each of the sections are transitions or circumferential spaces  190 ,  192 ,  194  and  196 . Specifically, transition  190  is the space between sections  180  and  182 , transition  192  is the space between sections  182  and  184 , transition  194  is the space between sections  184  and  186 , and transition  196  is the space between sections  186  and  180  of the next side (the left side). This space is defined as the circumferential width from the cutting edge  44  of the last tooth of a section to cutting edge  44  of the first tooth in the next section. Specifically, transition  190  is the circumferential width from cutting edge  44  of tooth  132 G of section  180  to cutting edge  44  of tooth  132 H in the next section  182 , which is defined as angle l. Transition  192  is the circumferential width from cutting edge  44  of tooth  132 M of section  182  to cutting edge  44  of tooth  132 N in the next section  184 , which is defined as angle m. Transition  194  is the circumferential width from cutting edge  44  of tooth  132 P of section  184  to cutting edge  44  of tooth  132 Q in the next section  186 , which is defined as angle q. Transition  196  is the circumferential width from cutting edge  44  of tooth  132 R of section  186  to cutting edge  44  of tooth  132 A in the next section  180  (which is on the other side or left side in this case), which is defined as angle s. 
   In accordance with one of the features of the invention, the circumferential width or section angle g is 36.015°, the section angle h is 44.985°, the section angle j is 30.015°, the section angle k is 20°, the transition angle l is 9°, the transition angle m is 9.985°, the transition angle q is 10°, and the transition angle s is 20°. 
   In accordance with yet one more feature of the invention, it has been discovered that alternating the number of teeth in adjacent sections from odd to even provides additional benefits including noise reduction. 
   Accordingly, the improved saw blade of the above embodiments is simplified, provides an effective, safe, inexpensive, and efficient device which achieves all the enumerated objectives, provides for eliminating difficulties encountered with prior devices, and solves problems and obtains new results in the art. 
   In the foregoing description, certain terms have been used for brevity, clearness and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirement of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed. 
   Moreover, the description and illustration of the invention is by way of example, and the scope of the invention is not limited to the exact details shown or described. 
   Having now described the features, discoveries and principles of the invention, the manner in which the improved saw blade is constructed and used, the characteristics of the construction, and the advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangements, parts and combinations, are set forth in the appended claims.

Technology Classification (CPC): 8