Abstract:
A wood cutting band saw blade includes a cutting edge and a back edge, wherein the cutting edge is defined by a plurality of teeth spaced relative to each other. The plurality of teeth include a plurality of set teeth each having a tip, each defining a bend plane, and each including a shelf located at least partially between the tip and the bend plane for reducing saw dust passing to the kerf and accumulating on the band saw blade. Each of the set teeth may define a relief surface and a cutting surface where the relief surface extends from one side of the tip in a direction opposite that of the movement of the band saw blade and the cutting surface extends from another side of the tip. The shelf includes a shelf surface extending from the cutting surface and may terminate in a shelf tip.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to saw blades and, more particularly, to wood cutting band saw blades having a tooth form configured to reduce saw dust passing to the kerf walls and to the side walls of the band saw blade. 
     BACKGROUND INFORMATION 
     It is desirable to minimize the amount of sawdust remaining on the kerf walls when cutting work pieces. For example, excessive saw dust remaining on wood products, such as pallets, will tend to collect in the eyes and/or breathing passages of workers handling the pallets. In addition, dust can be particularly problematic when cutting frozen wood, such as logs. In particular, the fast-moving blade creates friction that, in turn, heats the wood and allows the wood to release moisture. The moisture collects on the kerf walls and sides of the band saw blade, and binds the sawdust thereon into a glue-like mixture. Then, the glue-like mixture freezes when the blade exits the work piece, resulting in a frozen, hardened layer of saw dust on the side walls of the blade. The frozen layer of sawdust can cause unwanted vibrations in the saw blade, and if sufficiently thick, can cause the blade to fracture. 
     U.S. Pat. No. 820,969 to Grelck (“Grelck”) shows a wood-cutting saw blade wherein the front of each tooth is provided with one or more projections which act as “sawdust-removers” to remove the sawdust as it is produced. More specifically,  FIG. 1  shows a saw blade with each tooth “b” provided on its front or cutting edge and below its point with a projection “c”. In  FIG. 4 , each tooth is provided with two such projections “c” and “d” spaced relative to each other. Grelck teaches that only the very end of the point of the tooth is set, and thus the bend plane of each tooth is spaced above the projections “c” and “d”. Accordingly, saw dust which is created along the sides of the points that have been set is not captured by the projections “c” and “d” as they are below the bend plane. Instead, saw dust passes by either side of the projections in the direction of the kerf walls thereby building up and causing the above-described problems. 
     Accordingly, it is an object of the present invention to provide a saw blade which better reduces the quantity of saw dust collecting on the kerf walls. 
     It is also an object to overcome one or more of the above-described drawbacks and disadvantages of the prior art. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a wood cutting band saw blade that when cutting wood produces saw dust and forms a kerf. The band saw blade comprises a cutting edge defined by a plurality of teeth spaced relative to each other, and a back edge located on an opposite side of the band saw blade relative to the cutting edge. The plurality of teeth comprise a plurality of set teeth each having a tip, each defining a bend plane, and each comprising a shelf located at least partially between the tip and the bend plane for reducing saw dust passing to the kerf and accumulating on the band saw blade. 
     Preferably, each of the set teeth defines at least one relief surface and a cutting surface, where the relief surface extends from one side of the tip in a direction opposite that of the movement of the saw blade and terminating at one end of an intermediate surface, and the cutting surface extends from another side of the tip. Preferably, the shelf includes a shelf surface extending from the cutting surface and terminating at another end of the intermediate surface. 
     Another aspect of the present invention is directed to a wood cutting band saw blade having a lateral surface and generating dust during cutting of wood. The band saw blade comprises a base having a back edge and a cutting edge defined by a plurality of teeth spaced relative to each other and being located on an opposite side of the band saw blade relative to the back edge. The plurality of teeth comprise a plurality of set teeth, of which each set tooth defines a tip, a bend plane and a dust gap extending approximately between an outer lateral point of the tip and a lateral surface of the base. The band saw blade further comprises means for reducing the quantity of dust passing through the dust gap. 
     A further aspect of the present invention is directed to a wood cutting band saw blade having a lateral surface and generating dust during cutting of wood. The band saw blade comprises a base having a back edge and a cutting edge defined by a plurality of teeth spaced relative to each other and being located on an opposite side of the band saw blade relative to the back edge. The plurality of teeth comprise a plurality of set teeth, of which each set tooth defines a tip, a bend plane and a dust gap dimension extending approximately between an outer lateral point of the tip and a lateral surface of the base. The band saw blade further comprises means for reducing the dust gap dimension. In a preferred embodiment of the present invention, the means for reducing the dust gap dimension includes at least one shelf formed between the bend plane and the tip of a set tooth. In another embodiment of the present invention, the means for reducing the dust gap dimension further includes a relief portion extending from the tip of a set tooth at an acute angle to a transverse axis of the saw blade. 
     One advantage of the present invention is that the location of the shelf or like means for reducing the quantity of dust passing through the dust gap minimizes the collection of dust on both the kerf walls and sides of the saw blade. 
     Other advantages of the present invention will become readily apparent in view of the following detailed description of preferred embodiments and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevational view of a portion of a wood cutting band saw blade showing a pair of teeth comprising a shelf located between a tip and a bend plane in accordance with an embodiment of the present invention. 
         FIG. 2  is an enlarged cross-sectional view taken along line  2 - 2  of  FIG. 1  showing a pair of teeth adjacent to a kerf wall. 
         FIG. 3  is an enlarged cross-sectional view taken along line  3 - 3  of  FIG. 1 . 
         FIG. 4  is a side elevational view of a portion of a wood cutting band saw blade showing a single tooth having a generally linear shelf surface in accordance with another embodiment of the present invention. 
         FIG. 5  is a somewhat schematic, cross-sectional view of another embodiment of the wood cutting band saw blade of the present invention wherein each set tooth includes a shelf and a relief portion to further reduce or minimize the dust gap between the blade and kerf walls. 
         FIG. 6  is a somewhat schematic, partial top plan view of the band saw blade of  FIG. 5 . 
         FIG. 7  is a side elevational view of a portion of a wood cutting band saw blade showing a single tooth having two shelves in accordance with another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A wood cutting band saw blade in accordance with an embodiment of the present invention is illustrated generally at  10  in  FIG. 1 . The band saw blade  10  defines a cutting direction indicated by the arrow a, and comprises a band  12  having cutting edge  14  and a base  15  including a back edge  16 . The band saw blade  10  defines a longitudinal axis “L” and a transverse axis “T”. It will be appreciated by those of ordinary skill in the relevant art that the cutting edge  14  of the band saw blade  10  comprises a plurality of teeth  17 ,  17 ′,  17 ″( FIG. 2 ) etc., disposed along the cutting edge. It will also be appreciated that all or a subset of the teeth  17 ,  17 ′,  17 ″, etc. may be angled or set along a bend plane  18  as better seen in  FIG. 2 . 
     Referring now to  FIG. 2 , a plurality of the teeth  17 ′,  17 ″, etc. are each set at an angle A′, A″, etc. relative to axis A. In the preferred embodiments of the present invention, angle A′, A″, etc. as preferably within a range of approximately 75-89°, and most preferably approximately 84° (or approximately 1° to approximately 15° with respect to transverse axis T). It will be understood that Angles A′, A″, etc. may also vary from tooth to tooth in a particular pattern. Also, each of the teeth  17 ′,  17 ″, may be set in a manner such that they extend in directions which alternate from one side of transverse axis T of the band saw blade  10  to the other side as illustrated in  FIG. 2 . In another example, the pattern may comprise both set teeth and unset or straight teeth. In a preferred embodiment, the pattern may include five teeth comprising a first unset tooth and four set teeth, the latter four of which alternate from one side of the transverse  20  axis T to the other side. Other patterns also may be employed in accordance with the present invention. For example, U.S. patent application Ser. No. 09/435,108 entitled “Band Saw Blade Having Reduced Noise and Uniform Tooth Loading Characteristics”, assigned to the assignee hereof, and hereby incorporated herein by reference as part of the present disclosure, describes several tooth patterns that may include variously setting primary, secondary and tertiary teeth in such a manner as to minimize noise and vibration of the band saw blade. 
     Referring again to  FIGS. 1 and 2 , the teeth  17 ,  17 ′ each comprise a tip  20 ,  20 ′, a relief surface  22 ,  22 ′, and a cutting surface  24 ,  24 ′, and each tooth is separated from the next by an intermediate surface comprising a curvilinear base surface  26  defining a gullet  28 . The relief surface  22 ,  22 ′ and cutting surface  24 ,  24 ′ each extend from the tip  20 ,  20 ′, and preferably connect together with the curvilinear base surface  26  defining the gullet  28 . It will be understood that the curvilinear base surface  26  may be configured in a particular shape that assists in discharging dust and chips created during cutting. Such a configuration is described, for example, in U.S. Pat. No. 6,167,792, entitled “Improved Tooth Form For A Saw Blade”, assigned to the Assignee hereof, the entire contents of which is hereby incorporated herein by reference as part of the present disclosure. 
     In accordance with a feature of the present invention, each set tooth  17 ,  17 ′, etc. defines a shelf  30 ,  30 ′ extending from the cutting surface  24 ,  24 ′ and comprising a shelf surface  34 ,  34 ′ and a shelf tip  36 ,  36 ′. The shelf  30 ,  30 ′ is configured to function, as described in more detail below, to collect saw dust, e.g. various sized wood chips and other particulate matter generated during cutting of a kerf including a kerf wall  38  in a work piece  39 , as shown in  FIG. 2 , and to remove the collected dust away from the kerf wall  38 . It will be recognized that the shelf tip  36 ,  36 ′ may be of any suitable configuration including, e.g., a rounded configuration (not shown). 
     As used herein, the term shelf refers to any suitable structure which may capture and/or remove sawdust during cutting of a work piece such as, for example, a ledge-like structure extending outwardly from a cliff-like structure as illustrated in the disclosed embodiment. 
     It will be understood by one of ordinary skill in the pertinent art that the location and dimensions of the shelf  30 ,  30 ′ affects the functionality of the shelf in removing dust. For simplicity, the following will use tooth  17 ′ for an example in describing the location of the shelf  30 ′; however, it will be understood that this description may be equally applicable to all teeth disposed on the band saw blade  10 . As shown in  FIG. 2 , the distance between the tip  20 ′ and shelf tip  36 ′ is defined as “S 1 ,” and the distance between the tip  20 ′ and the bend plane  18  is defined as “B”. Also, the distance between the tip  20 ′ and the curvilinear base surface  26  is defined as “D”. If S 1  is set equal to or greater than B, then the shelf  30 ′ will not be in a proper location to “catch” and remove the dust cut from the kerf wall  38 . Specifically, a dust gap “DG” is defined between a lateral point  40 ′ of the tooth  17 ′ (which also establishes the kerf wall  38 ) and a side surface  42  at the base of the band saw blade  10 . Effectively, the shelf  30 ′ reduces the size of the dust gap or creates an effective dust gap “EDG” that is substantially less than DG. 
     It has been found that S 1  preferably ranges from between approximately 0.06 inch and approximately 0.12 inch, and is most preferably approximately 0.09 inch, where B is approximately 0.20 inch and D is approximately 0.30 inch. 
     In order to quantify a percent reduction of the dust gap size, the ratio of S 1 /B is utilized. The present inventor has determined that the ratio of S 1 /B preferably ranges between approximately 0.25 and approximately 0.75, more preferably ranges between approximately 0.30 and approximately 0.60, and most preferably is approximately 0.45. Accordingly, a shelf depth of approximately ⅓ D (or approximately ½ the depth of the bend plane) is sufficient to prevent choking and provide a desirable effective dust gap. It will be understood that these dimensional parameters apply to straight or unset teeth as well as to set teeth. 
     It also will be appreciated that the width of the effective dust gap can not only be manipulated by adjusting the depth (dimension S 1 ) of the shelf, but also by adjusting the set angle A′ of the tooth  17 ′. For example, increasing the set angle A′ relative to the transverse axis T, as illustrated in  FIG. 2 , will necessarily reduce the width of the effective dust gap. 
     The configuration of the shelf  30 ′ also influences the ability of the shelf to remove dust. For example, it will be recognized that the available space created by the length of the shelf surface  34 ′ must be sufficient to prevent dust from “choking” or over-filling the shelf. With reference to  FIG. 1 , it has been found that the length “L 1 ” of the shelf surface  34 ′ is preferably between approximately 0.06 inch and approximately 0.10 inch, and most preferably is approximately 0.08 inch. The length L 1  may be made between the projected intersection of the cutting surface  24 ′ and shelf surface  34 ′ and an outer edge of the shelf tip  36 ′. 
     The shelf surface  34 ,  34 ′ also may be angled to optimize dust capture and prevent, e.g., choking as discussed above. In particular, by angling the shelf with respect to the back edge  16  of the blade, the quantity of sawdust captured and the re-direction of the chip flow, e.g., to the gullet  28  for sweeping the chips out of the kerf is increased. For example, while shelf surface  34 ,  34 ′ may comprise a first portion  34   a ,  34 ′ a  that may be generally parallel to the back edge  16  of the band saw blade  10 , a second portion  34   b ,  34 ′ b  is provided that is disposed at an angle “A 1 ” relative to the back edge. Angle A 1  is preferably between approximately 10° and approximately 20°, and is most preferably approximately 15° in the direction of the back edge. However, it will be understood that less preferably the shelf surface may be angled in a direction away from the back edge (not shown). Optionally, the first portion  34   a ,  34 ′ a  may be angled relative to the back edge  16  at between approximately 4° and approximately 10°, and most preferably approximately 7° (not shown). 
     Another embodiment of the band saw blade of the present invention is shown generally at  110  in  FIG. 4 . The band saw blade  110  is similar in many respects to the band saw blade  10  described above, and therefore like reference numerals preceded by the number 1 are used to indicate like elements. 
     In this embodiment, shelf surface  134  of the band saw blade  110  defines a generally planar configuration over substantially the entire shelf length, and a shelf surface angle A 2  relative to the back edge  116  of between approximately 4° and approximately 10°, and most preferably approximately 7°. 
     Tests conducted cutting frozen cherry at a band speed of approximately 5500 feet per minute (FPM) and a board speed of approximately 65 FPM, using a band saw blade of the present invention being 1.348 inch high, by 0.042 inch thick and having 1 tooth per inch (TPI), was found to have a 70-90% weight percent reduction in residual saw dust on the finished boards as compared to cutting with a conventional band saw blade. 
     Referring now to  FIGS. 1 and 3 , the band saw blade  10  may also comprise a bump  42  that may function to urge chips received from a tooth  17 ′ to be redirected toward the cutting edge  14  and out of the kerf. The bump preferably includes a height H that ranges from approximately 0.04 inch through approximately 0.06 inch, and a lateral width W which ranges from between approximately 0.005 inch to approximately 0.015 inch as measured from a respective side of the band saw blade  10 . The bump  42  is preferably formed by swaging. It will be appreciated that swaging the bump (and by not locating the bump at the traditional location at the base of the rake face) substantially reduces the chances of the formation of harmful stress risers in the band saw blade  10 . 
     Turning now to  FIGS. 5 and 6 , another embodiment of a band saw blade in accordance with the present invention is shown generally at  210 . The band saw blade  210  is similar in many respects to the band saw blade  10  described above, and therefore like reference numerals preceded by the number 2 are used to indicate like elements. In this embodiment, each of the set teeth includes a shelf  230  and a relief portion to further reduce or minimize the dust gap between the blade  10  and the kerf walls (not shown). 
     The band saw blade  210  is generally similar to the band saw blade  10  of  FIGS. 1-3 ; however, each set tooth  217 ′,  217 ″, etc. further includes a relief portion  244 ′,  244 ″, respectively, formed on the upper corner of the tooth on the side facing the respective kerf wall  238 . As illustrated in  FIG. 5 , the relief portions  244 ′,  244 ″ each define a relief angle RA′, RA″ (shown in  FIG. 5 ). The relief portions form an angle which is preferably within the range of between approximately 0° and approximately 2° with respect to a plane defined by the unset tooth  220 . The relief portions  244 ′,  244 ″ function to locate the respective shelf  230  closer to the kerf wall  238  to thereby further reduce the dust gap DG to DG 1  and, in turn, decrease the effective dust gap from EDG to EDG 1 . The relief portion may also define a tangential angle “TA” (shown in  FIG. 6 ). In this way, the edge is relieved to reduce the effects of friction during cutting of a work piece (not shown). The angle TA is preferably within the range of between approximately 3° and approximately 6° with respect to a plane defined by the side of the blade body  210 . It will be understood that the dimensions and interrelationship of S 1  and B, as described above, applies to the current embodiment as well. The straight or unset tooth  220  provided in this embodiment also includes a shelf  230  similar to that described above. 
       FIG. 7  illustrates a band saw blade  310  in accordance with another embodiment of the present invention. The band saw blade  310  is similar in many respects to the band saw blade  10  described above, and therefore like reference numerals preceded by the number 3 are used to indicate like elements. The tooth  317  may be similar to teeth  17 ,  17 ′,  17 ″ and  117  described above in conjunction with  FIGS. 1-3  and  5 , although, the tooth  317  further includes a second shelf  346 . The second shelf  346  comprises a second shelf surface  348  and a second shelf tip  350 , and functions to re-direct chips which have passed the first shelf  330 . Each second shelf  346  has a dimension S 2  which is defined as the distance measured between the tip  320  of a particular tooth  317  and the second shelf tip  350 . The dimensions S 1  and B may both be determined in the same manner as discussed above in conjunction with  FIGS. 1 and 2 . It has been found that S 2  is preferably determined through the relationship of S 2 =(B+S 1 )÷2. Accordingly, for the range of S 1  given above, S 2  preferably is within the range of between 0.13 inch and 0.16 inch, and is most preferably 0.145 inch. It has been found that the shelf length L 2  (measured in a similar manner to L 1 ) is preferably approximately 70% to approximately 90% of L 1 . Most preferably, the shelf length L 2  is approximately 80% of L 1 . 
     In the operation of the band saw blade, the shelf operates to collect substantially all of the sawdust generated upon cutting the work piece and tends to force the collected dust upwardly and out of the kerf. As a result, very little dust is allowed to fall downwardly into the dust gap formed between the sides of the blade and kerf walls. Also, a substantial clearance is maintained between the base of the blade and the kerf walls, thereby significantly reducing friction between the blade and kerf walls and, in turn, minimizing vibrations and increasing blade life in comparison to prior art band saw blades. 
     As may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, numerous changes and modifications may be made to the above-described and other embodiments of the present invention without departing from its scope as defined in the appended claims. For example, the shelf or similarly functioning means, may take various different configurations while still performing the function of reducing the passage of saw dust into the kerf. In addition, the blade need not define any unset teeth; rather all teeth may alternate from one side of the transverse axis of the blade to the other. Accordingly, this detailed description of preferred embodiments is to be taken in an illustrative as opposed to a limiting sense.