Abstract:
An extended-life cutting blade is adapted for mounting on a hand-held cutting tool in multiple operative orientations. A single cutting blade may provide up to four independent shear edges, each of which has a useful life. The blade can be easily changed from an orientation adapted to cut a workpiece with one shear edge to a different operative orientation adapted to cut with a different shear edge by selecting an appropriate mount on the blade.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     The present application claims priority from U.S. Patent Application No. 60/______ entitled “EXTENDED CUTTING BLADES FOR HAND-HELD CUTTING TOOLS,” filed 10 Aug. 2001, and identified by Perkins Coie LLP Docket No. 31957-8010. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention relates to hand-held cutting tools, such as those used to cut fiber-cement siding.  
       BACKGROUND  
       [0003]     The exteriors of houses and other types of buildings are commonly covered with siding materials that protect the internal structures from external environmental elements. The siding materials are typically planks or panels composed of wood, concrete, brick, aluminum, stucco, wood composites or fiber-cement composites. Wood siding is popular, but it is costly and flammable. Wood siding also cracks causing unsightly defects, and it is subject to infestation by insects. Aluminum is also popular, but it deforms easily, expands and contracts in extreme climates and is relatively expensive. Brick and stucco are also popular in certain regions of the country, but they are costly and labor intensive to install.  
         [0004]     Fiber-cements siding (FCS) offers several advantages compared to other types of siding materials. FCS is made from a mixture of cement, silica sand, cellulose and a binder. To form FCS siding products, a liquid fiber-cement mixture is pressed and then cured to form FCS planks, panels and boards. FCS is advantageous because it is non-flammable, weather-proof, and relatively inexpensive to manufacture. Moreover, FCS does not rot or become infested by insects. FCS is also advantageous because it may be formed with simulated wood grains or other ornamental designs to enhance the appearance of a building. To install FCS, a siding contractor cuts the panels or planks to a desired length at a particular job site. The siding contractor then abuts one edge of an FCS piece next to another and nails the cut FCS pieces to the structure. After the FCS is installed, trim materials may be attached to the structure and the FCS may be painted.  
         [0005]     Although FCS offers many advantages over other siding materials, it is difficult and expensive to cut. Siding contractors often cut FCS with a circular saw having an abrasive disk. Cutting FCS with an abrasive disk, however, generates large amounts of very fine dust that creates a very unpleasant working environment. Siding contractors also cut FCS with shears having opposing blades, as set forth in U.S. Pat. No. 5,570,678 and U.S. Pat. No. 5,722,386, which are herein incorporated in their entireties by reference. Although the shears set forth in these patents cut a clean edge in FCS without producing dust, many siding contractors prefer to use a hand-held tool because they are accustomed to cutting siding with hand saws. Therefore, in light of the positive characteristics of FCS and the need for a hand-held cutting tool, it would be desirable to develop a hand-held cutting tool that quickly cuts clean edges through FCS without producing dust.  
         [0006]     To meet the demand for a hand-held FCS cutting tool, the present inventors developed a hand-held tool with a reciprocating cutting blade which is the subject of U.S. Pat. No. 5,993,303 (“the &#39;303 patent,” the entirety of which is incorporated herein by reference). The hand-held tool of the &#39;303 patent may have a hand-held motor unit with a housing, a motor inside the housing, and a switch operatively coupled to the motor to selectively activate the motor. A head having a casing may be attached to the housing of the motor unit. The head may also have a reciprocating drive assembly coupled to the motor.  
         [0007]     The hand-held cutting tool of the &#39;303 patent also has a blade set with first and second fingers attached to either the casing or the motor housing, and a reciprocating cutting member between the first and second fingers. The first finger may have a first guide surface and a first interior surface. Similarly, the second finger may have a second guide surface and a second interior surface. The first and second guide surfaces are preferably in a common plane, and the first and second interior surfaces are spaced apart from one another by a gap distance. The reciprocating cutting member of the blade set has a body with a first width approximately equal to the gap distance and a reciprocating blade projecting from the body. The reciprocating blade has a first side surface facing the first interior surface of the first finger, a second side surface facing the second interior surface of the second finger, and a top surface. The first side surface of the blade is preferably spaced apart from the first interior surface of the first finger by 0.040-0.055 inches for cutting ¼ inch and 5/16 inch thick fiber-cement siding. Similarly, the second side surface of the blade is spaced apart from the second interior surface of the second finger by 0.040-0.055 inches. The distance between the first and second side surfaces of the blade and the first and second fingers, respectively, may be approximately 13%-22% of the thickness of the fiber-cement siding workpiece.  
         [0008]     The top surface of the reciprocating blade may also have a width less than the first width of the body. For example, the top surface of the reciprocating blade may be between 0.140 and 0.165 inches, and more preferably between 0.160 and 0.165 inches for cutting ¼ inch and 5/16 inch thick fiber-cement siding. The top surface may also have a curvature concave with respect to the first and second guide surfaces of the first and second fingers.  
         [0009]     In operation, a drive assembly is operatively coupled to the reciprocating member to reciprocate the blade into and out of the gap between the fingers. As the drive assembly moves the blade into the gap between the fingers, the top surface of the blade and the straight guide surfaces of the fingers shear the fiber-cement siding.  
         [0010]     One drawback of the hand-held tool of the &#39;303 patent, however, is that the fingers can be worn away relatively quickly in cutting the abrasive FCS. If the fingers are worn, the edge of the finger may not cleanly break the surface of the FCS or the spacing between the reciprocating blade and the fingers can fall outside desirable tolerances. FCS is a relatively brittle material that tends to crack along rough edges and unpredictable paths. Excessive wear of the shear edge and/or the interior surface of a finger can lead to unacceptable cutting of the FCS. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is an isometric view of a hand-held cutting tool and a blade set in accordance with one embodiment of the invention.  
         [0012]      FIG. 2  is a rear isometric view of a casing and blade set in accordance with an embodiment of the invention.  
         [0013]      FIG. 3  is a front isometric view of the casing and blade set of  FIG. 2 .  
         [0014]      FIG. 4A  is a bottom elevational view of one blade of the blade set of  FIGS. 1-3 .  
         [0015]      FIG. 4B  is a side elevational view of the blade of  FIG. 4A .  
         [0016]      FIG. 4C  is a bottom isometric view of the blade of  FIG. 4A .  
         [0017]      FIG. 5A  is a bottom elevational view of a blade in accordance with another embodiment of the invention.  
         [0018]      FIG. 5B  is a side elevational view of the blade of  FIG. 5A .  
         [0019]      FIG. 5C  is a bottom isometric view of the blade of  FIG. 5A .  
         [0020]      FIG. 6  is a side isometric view of a casing and blade set in accordance with an embodiment of the invention utilizing a pair of the blades shown in  FIGS. 5A-5C .  
     
    
     DETAILED DESCRIPTION  
       [0021]     Various embodiments of the present invention provide cutting heads and blades for hand-held cutting tools and methods of reconfiguring a cutting head for a hand-held cutting tool. The following description provides specific details of certain embodiments of the invention illustrated in the drawings to provide a thorough understanding of those embodiments. It should be recognized, however, that the present invention can be reflected in additional embodiments and the invention may be practiced without some of the details in the following description.  
         [0022]      FIG. 1  is an isometric view of a hand-held cutting tool  10  for cutting a workpiece W, which may comprise FCS. The cutting tool  10  has a motor unit  20  with a housing  22 , a motor  24  (shown schematically in phantom) inside the housing  22 , and a switch  26  operatively coupled to the motor  24 . The housing  22  preferably has a handle  27  configured to be gripped by an operator. One suitable motor unit  20  is the No. 3208-90 electric motor unit manufactured by Black and Decker Corporation. Another suitable motor unit  20  is the No. 7802 pneumatic motor unit manufactured by Ingersoll-Rand Corporation.  
         [0023]     The output of the motor unit  20  may be converted into a reciprocal motion with a head  30  having a casing  32  and a reciprocating drive assembly  36  (shown schematically in phantom). The casing  32  is attached to the housing  22  of the motor unit  20 . Additionally, the reciprocating drive assembly  36  is coupled to the motor  24  via a gear assembly  38  (shown schematically in phantom) to translate the rotational output from the motor unit  20  into a reciprocating motion. A suitable head  30  is the shear head manufactured by Kett Tool Co., as set forth in U.S. Pat. No. 4,173,069, entitled “Power Shear Head,” which is herein incorporated by reference.  
         [0024]     The cutting tool  10  may also have a blade set  50  with a first blade  60   a  attached to one side of the head  30 , a second blade  60   b  attached to another side of the head  30 , and a cutting member  90  between the first and second blades  60   a  and  60   b.  The first and second blades  60   a  and  60   b  are preferably attached to the head  30  to space the blades  60   a - b  from one another by a gap  66  in which the cutting member  90  may be received. In the illustrated embodiment, the blades  60   a - b  are attached to the casing  32 . The casing  32  may include a pair of spaced-apart flanges  40   a  and  40   b  which define a support of the casing.  
         [0025]      FIGS. 2 and 3  are perspective views of the blade set  50  used with the hand-held cutting tool  10 . The cutting member  90  may have a body  91  with a first width approximately equal to a gap distance G between the first shear face  62   a  of the first blade  60   a  and the first shear face  62   b  of the second blade  60   b . The cutting member  90  may also have reciprocating blade  92  projecting from the body  91  between the first and second blades  60   a  and  60   b . The reciprocating blade  92  has a first side surface  94  facing the first blade  60   a , a second side surface  95  facing the second blade  60   b , and a curved top surface  96 . The edge along the top surface  96  and the first side surface  94  defines a first cutting edge  97  of the reciprocating blade  92 , and the edge along the top surface  96  and the second side surface  95  defines a second cutting edge  98  of the reciprocating blade  92 .  
         [0026]     FIGS.  4 A-C illustrate a blade  60  in accordance with one embodiment of the invention. The first blade  60   a  and the second blade  60   b  shown in  FIGS. 1-3  may be identical. Only one blade  60  is shown in FIGS.  4 A-C, but it should be understood that the first and second blades  60   a - b  of  FIGS. 1-3  may have the same structure shown in FIGS.  4 A-C.  
         [0027]     The blade  60  has a body  61 . The body includes a first shear face  62  and a second shear face  64 . The first and second shear faces  62  and  64  may be substantially planar and parallel to one another. The first and second shear faces  62  and  64  are spaced from one another to define a thickness of the body  61 . A guide surface  80  extends between the first and second shear faces  62  and  64  along a first elongate edge of the body  61 . A first shear edge  82  is defined at the junction between the guide surface  80  and the first shear face  62 . A second shear edge  84  is defined at the junction between the guide surface  80  and the second shear face  64 . The first and second shear edges  82  and  84  may be parallel to one another and spaced from one another by the thickness of the body  61 .  
         [0028]     As noted above, the blade  60  may be carried by the casing  32  of the housing  30 . The blade  60  may be attached to the casing  32  in at least two different operative orientations, with a first mount  70   a  mating with the casing  32  to orient the blade in a first operative orientation and a second mount  70   b  used to mount the blade  60  in a second operative orientation. In the illustrated embodiment, the first mount  70   a  comprises a first pair of mounting holes passing through the thickness of the body  61  and the second mount  70   b  comprises a second pair of mounting holes passing through the thickness of the body  61 . In particular, the blade  60  has a central mounting hole  66 , which may be disposed generally midway along the length of the blade  60 . A first outer mounting hole  68  is spaced a fixed mounting distance D from the central mounting hole  66  in a first direction and a second outer mounting hole  69  is spaced the same fixed mounting distance D from the central mounting hole  66  in a second direction.  
         [0029]     In the illustrated embodiment, the central mounting hole  66  is shared by the first and second mounts  70   a - b . Hence, the first mount  70   a  includes the central mounting hole  66  and the first outer mounting hole  68 , whereas the second mount  70   b  includes the central mounting hole  66  and the second outer mounting hole  69 . If so desired, more than three mounting holes may be employed. In such a circumstance, the first mount  70   a  may comprise two of these mounting holes while the second mount  70   b  may comprise two different mounting holes.  
         [0030]     The mounting distance D is selected to coincide with the distance D between a pair of spaced-apart mounting rods  42  and  44  (best seen in  FIG. 1 ). The first mounting rod  42  may pass through the central mounting hole  66  and the second mounting rod  44  may pass through the first outer mounting hole  68  or the second outer mounting hole  69 , depending on the operative orientation of the blade  60 .  
         [0031]     The blade  60  of FIGS.  4 A-C illustrate mounting holes  66 ,  68  and  69  which pass through the thickness of the body  61 . It should be understood, though, that the mounting holes  66 ,  68  and  69  could instead be replaced with mounting points bearing the same spatial relationship as the illustrated mounting holes. Such a mounting point may, for example, comprise a recess (not shown) or protrusion (not shown) carried by one or both of the shear faces  62  and  64 . The casing  32  of the housing  30  may be adapted to mate with such recesses or protrusions to fix the position of the blade  60  in one of the desired operative orientations.  
         [0032]      FIGS. 2 and 3  illustrate the first blade  60   a  and the second blade  60   b  carried by the housing  30 . In particular, the first mounting rod  42  passes through the support flanges  40   a - b , through the central mounting hole  66  of each of the blades  60   a - b , and through the body  91  of the cutting member  90 . The first mounting rod  42  may define an axis about which the cutting member  90  may pivot when reciprocating. The second mounting rod  44  passes through the first outer mounting holes  68  (not visible in  FIGS. 2 and 3 ) of each of the blades  60   a - b . Hence, each of the blades  60   a - b  is mounted to the casing  32  via its first mount ( 70   a  in FIGS.  4 A-C). The second outer mounting hole  69  is disposed distally of the casing  32 .  
         [0033]     The first shear face  62   a  of the first blade  60   a  and the first shear face  62   b  of the second blade  60   b  are oriented toward one another and are positioned adjacent the cutting member  90 . The second shear face  64   a  of the first blade  60   a  abuts the first support flange  40   a  of the casing  32  and may lie flush against the inner surface of the first support flange  40   a . The second shear face  64   b  of the second blade  60   b  may also be oriented outwardly away from the cutting member  90  and be mounted flush against an inner surface of the second support flange  40   b  of the casing  32 .  
         [0034]     With the blades  60   a - b  mounted in this fashion, the first shear edges  82   a - b  of the blades  60   a - b  are positioned to cooperate with the cutting member  90  to shear the workpiece W. This relative positioning of the first shear edges  82   a - b  with respect to the reciprocating cutting member  90  is achieved by the fixed spacing and orientation of the first shear edge  82  of each blade  60  with respect to the first pair of mounting holes  70   a . This is illustrated in  FIG. 4B  by noting that the central mounting hole  66  is spaced a distance S 1  from the first shear edge  82  and the first outer mounting hole  68  is space a distance S 2  from the first shear edge  82 . The distances S 1  and S 2  may be the same or they may differ from one another.  
         [0035]      FIG. 4B  indicates that the second outer mounting hole  69  is also spaced the same distance S 2  from the guide surface  80  of the blade  60 . As a consequence, the orientation and spacing of the second shear edge  84  of the blade  60  with respect to the second mount  70   b  is the same spacing and orientation between the first mount  70   a  and the first shear edge  82 . This allows the blade to be reoriented on the head  30  to position the second shear edge  84  adjacent to the reciprocating cutting member  90  for cooperation therewith to cut a workpiece W simply by switching from the first mount  70   a  to the second mount  70   b.    
         [0036]     When the cutting edge of a finger of the hand-held FCS cutting tool of the &#39;303 patent becomes dull or the facing surface of the finger becomes too worn, the finger is commonly replaced with a new finger. Given the strength and abrasion-resistant requirements of such a finger, though, the finger can be fairly expensive. The effective life of a blade  60  in accordance with the embodiment of  FIGS. 1-4  is effectively double the total life of one of the fingers used in connection with the tool of the &#39;303 patent. When the first shear edge  82  of the blade  60  becomes dull, the blade  60  can be detached from the casing  32 . Rather than disposing of the blade  60 , the blade can be flipped lengthwise to position the second outer mounting hole  69  to receive the second mounting rod  44  therethrough. This orients the first shear face  62  outwardly into abutment with the casing  32  and spaces the first shear edge  82  transversely outwardly from the cutting member  90 . Mounting the blade in this position also orients the second shear face  64  inwardly toward the cutting member  90  and positions the second shear edge  84  adjacent the reciprocating blade  92  to cooperate with the cutting member  90  to cut a workpiece W. The second shear edge  84  was previously spaced transversely outwardly from the cutting member  90  when the cutting member  90  sheared the workpiece W with the first shear edge  82 . As a result, the second shear edge  84  will remain sharp and ready for use even if the blade  60  has already been used to cut a number of workpieces W using the first shear edge  82 .  FIGS. 5-6  illustrate an alternative embodiment of the invention. The blade  60  of  FIGS. 1-4  effectively doubles the useful life of the blade by providing a pair of shear edges  82  and  84 , each of which can be selectively positioned adjacent the reciprocating cutting member  90  to shear a workpiece W. The blade  160  of  FIGS. 5-6  effectively quadruples the life of a single blade by providing four spaced-apart shear edges  182 ,  184 ,  186 , and  188 , each of which can be positioned to cut a workpiece with the cutting member  90 .  
         [0037]     Much like the blade  60  of FIGS.  4 A-C, the blade  160  of FIGS.  5 A-C has a first shear face  162  and a second shear face  164 . The shear faces  162  and  164  are spaced from one another to define a thickness of the body  161 . A first guide surface  180  extends between the first and second shear faces  162  and  164  along a first elongate edge of the body  161 . A second guide surface  181  extends between the first and second shear faces along a second elongate edge of the body  161 . The first and second guide surfaces  180  and  181  may be generally parallel to one another, as shown. A first shear edge  182  is defined at the junction between the first guide surface  180  and the first shear face  162 . A second shear edge  184  is defined at the junction between the first guide surface  180  and the second shear face  164 . A third shear edge  186  is defined at the junction between the second guide surface  181  and the first shear face  162 . A fourth shear edge  188  is defined at the junction between the second guide surface  181  and the second shear face  164 .  
         [0038]     The blade  160  has at least five mounting points by which the blade  160  can be mounted to the housing  30  of the hand-held tool  10 . These mounting points are typified in the drawings as mounting holes which pass through the thickness of the body  161 . In an alternative embodiment, the mounting points may comprise protrusions or recesses in the faces  162  and  164  of the blade  160 , much as noted above in connection with the blade  60 .  
         [0039]     The blade  160  may include at least one central mounting hole  166 , a first outer mounting hole  168 , a second outer mounting hole  169 , a third outer mounting hole  178 , and a fourth outer mounting hole  179 . If a single central mounting hole  166  is employed, each of the outer mounting holes  168 ,  169 ,  178 , and  179  may be spaced the same fixed mounting distance D from the central mounting hole  166 . In the illustrated embodiment, the blade  160  includes two central mounting holes. The first central mounting hole  166  is spaced the fixed mounting distance D from the first outer mounting hole  168  and from the second outer mounting hole  169 . A second central mounting hole  176  is spaced the same mounting distance D from the third outer mounting hole  178  and the fourth outer mounting hole  179 .  
         [0040]     The first central mounting hole  166  and the first outer mounting hole  168  define a first pair of mounting holes  170   a . The first central mounting hole  166  and the second outer mounting hole  169  define a second pair  170   b  of mounting holes. The second central mounting hole  176  and the third outer mounting hole  178  define a third pair  170   c  of mounting holes. The second central mounting hole  176  and the fourth outer mounting hole  179  define a fourth pair  170   d  of mounting holes.  
         [0041]      FIG. 6  illustrates a first blade  160   a  and a second blade  160   b  attached to the casing  32  of the housing  30 . Each of the blades  160   a - b  is attached to the casing  32  via the first pair ( 170   a  in  FIG. 5B ) of mounting holes by passing the first and second mounting rods  42  and  44  therethrough. This orients the first shear edge  182   a  of the first blade  160   a  and the first shear edge  182   b  of the second blade  160   b  adjacent the cutting member  90  to cut a workpiece W.  
         [0042]     Because the mounting holes of each pair  170  are spaced from one another the same mounting distance D, the blade  160  can be reoriented in four different operative orientations by passing the mounting rods  42  and  44  through different pairs  170  of mounting holes in the blade  160 . Each of the pairs  170  of mounting holes is spaced a fixed distance from and has a fixed orientation with respect to an associated one of the shear edges. In particular, the first pair  170   a  of mounting holes is associated with the first shear edge  182 , the second pair  170   b  of mounting holes is associated with the second shear edge  184 , the third pair  170   c  of mounting holes is associated with the third shear edge  186 , and the fourth pair  170   d  of mounting holes is associated with the fourth shear edge  188 . By attaching the blade  160  to the casing  32  with the mounting rods  42  and  44  extending through any one of the four pairs  170  of mounting holes, the shear edge associated with the selected pair of mounting holes will be positioned to cooperate with the cutting member  90  to shear a workpiece W. As a consequence, by simply flipping the blades  160   a  and  160   b  to different operative orientations with respect to the casing  32 , each blade  160   a - b  can provide four different shear edges for cutting workpieces W. This effectively quadruples the life of the blades.  
         [0043]     Another embodiment of the invention provides a method of reconfiguring a cutting head for a hand-held cutting tool such as the cutting tool  10  shown in  FIG. 1 , though other designs (including, but not limited to, the embodiment of  FIGS. 5-6 ) may be employed instead. In a first operative orientation of the blades  60   a  and  60   b , the first shear edge  62  of each blade is positioned adjacent the reciprocating cutting member  90  for cooperation therewith and the second shear edge  64  of each blade  60  is spaced transversely outwardly of both the reciprocating cutting member  90  and the first shear edge  62 . In one method of the invention, the first mount  70   a  of the first blade  60   a  is detached from the casing  32 . The body  61  of the first blade  60   a  is turned and the second mount  70   b  of the first blade  60   b  is mated to the casing  32  to attach the first blade  60  to the casing  32  in a second operative orientation. In this second operative orientation, the second shear edge  64   a  of the first blade  60   a  is positioned adjacent the reciprocating cutting member  90  for shearing a workpiece W and the first shear edge  62  of the first blade  60  is positioned transversely outwardly of both the reciprocating cutting member  90  and the second shear edge of the first blade. Much the same process can be used to reorient the second blade  60   b  to position its second shear edge  64   b  adjacent the cutting member  90 .  
         [0044]     From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.