Abstract:
Apparatus and methods of processing fiber-cement workpieces to form fiber-cement shake panels. One embodiment of such a method comprises positioning a cured fiber-cement workpiece over an anvil plate having at least one slot and driving a cutting blade along a straight, vertical path to pass a cutting edge of the cutting blade through the workpiece. The process can optionally include coating the fiber-cement panels before installing the fiber-cements panels on a wall.

Description:
TECHNICAL FIELD 
       [0001]    This technology generally relates to cutting machines and knife/die apparatus for cutting fiber-cement materials to form, for example, shake-panel siding used on or in houses and other structures. 
       BACKGROUND 
       [0002]    The exterior surfaces of houses and other structures are often protected by exterior siding products made from wood, vinyl, aluminum, bricks, stucco, fiber-cement and other materials. Wood and fiber-cement siding (FCS) products, for example, are generally planks, panels or shakes that are attached to plywood or composite walls. Although wood siding products are popular, wood siding can become unsightly or even defective because wood generally rots, warps or cracks over time. Wood siding products are also highly flammable and subject to insect damage. FCS is an excellent alternative building material because it is nonflammable, weatherproof, relatively inexpensive to manufacture, and does not use the limited remaining cedar or fir resources. FCS also does not rot, nor is it consumed by insects. 
         [0003]      FIG. 1  shows a prior art fiber-cement shake-panel  20  having a length L extending along a longitudinal direction and widths W 1  and W 2  extending along a direction transverse relative to the length L. The shake-panel  20  has side edges  23  separated from each other by the longitudinal direction, a top edge  22  extending along the longitudinal dimension between the upper ends of the side edges  23 , and a bottom edge  24  extending along the longitudinal dimension between the bottom ends of the side edges  23 . The top and bottom edges  22  and  24  are typically substantially parallel to each other and separated by a constant widthwise dimension or varying widthwise dimensions (e.g., W 1  or W 2 ). The shake-panel also includes a web portion  32  and a plurality of shake sections  30   a  and  30   b  of different lengths L s1  and L s2  projecting from the web portion  32 . The individual shake sections  30   a  and  30   b  are separated by slots  28  such that the shake sections  30   a  and  30   b  have various widths corresponding to the distance between adjacent slots  28 . 
         [0004]      FIG. 2  illustrates an early prior art cutting machine  34  suitable for forming the shake-panel  20  shown in  FIG. 1 . Referring to  FIG. 2 , the cutting machine  34  includes a frame  36 , a plurality of cutting stations  35   a - 35   d , and a plurality of rollers  58  for supporting and advancing a sheet of fiber-cement to be cut. The cutting stations  35   b  and  35   c  are configured to cut the slots  28  shown in the shake panel  20  of  FIG. 1 . The cutting station  35   b  includes a slot cutting assembly  53  having a blade holder  54 , a plurality of cutting blades  56  attached to the blade holder  54 , and an actuator  60  for driving the blade holder  54  along rotational path R 1 . Each cutting blade  56  is configured to cut an individual slot  28  shown in the shake panel  20 . The blade holder  54  is pivotally connected to the frame  36  such that the actuator  60  moves the blade holder  54  along the rotational path R 1  between a cutting position (lowered position not shown in  FIG. 2 ) and a retracted position (raised position shown in  FIG. 2 ). The cutting station  35   c  includes a cutting assembly  63  having a blade holder  62  pivotally connected to the frame, a plurality of slot cutting blades  64  attached to the blade holder  62 , and an actuator  60  coupled to the blade holder  62  and the frame  36  to rotate the cutting assembly  63  along another rotational path R 2 . 
         [0005]      FIG. 3  illustrates a cutting assembly  63   a  used in a later cutting machine described in U.S. patent application Ser. No. 11/371,452 filed on Mar. 8, 2006, which is incorporated herein by reference in its entirety. The cutting assembly  63   a  includes a blade holder  62   a , a plurality of cutting blades  64   a  attached to the blade holder  62   a , and a lower anvil  70  with a plurality of slots  72  configured to receive respective cutting blades  64   a . In operation, a fiber-cement workpiece (not shown) is gripped between rollers  58   a  and drive belts  59  that move the workpiece along a path P until the workpiece is positioned at a desired location between the cutting blades  64   a  and slots  72 . An actuator (not shown in  FIG. 3 ) rotates the workpiece holder  62   a  downwardly as indicated by arrow R so that the cutting blades  64   a  pass through the fiber-cement workpiece and into corresponding slots  72 . The rollers  58   a  and/or the belts  59   a  then drive the workpiece along the path P to withdraw the workpiece from the cutting blade  64   a , and then the actuator rotates the workpiece holder  62   a  upwardly into the position illustrated in  FIG. 3 . 
         [0006]    PacTool International, Ltd. (PacTool), the assignee of the present invention, developed the cutting machines shown in  FIGS. 2 and 3 . Although the existing cutting machines illustrated in  FIGS. 2 and 3  are suitable for forming the shake-panel  20  illustrated in  FIG. 1 , they required a significant amount of maintenance that increased the operating cost. For example, the shape of the cutting blades  64   a  and the rotational motion of the blade holder  62   a  required a significant amount of force to drive the cutting blades through the fiber-cement workpiece. This generally caused a sudden fracture in the fiber-cement workpiece that would in turn transmit significant impact forces to the lower plate  70 , the blade holder  62   a  and the frame  36 . The impact forces were so great that welded connections between members of the frame  36  cracked and broke apart, and other parts of the machine would wear quickly. Therefore, PacTool sought to improve the longevity of the cutting machine. 
         [0007]    In addition to the high operational costs of the existing cutting machines, the fiber-cement industry is moving toward pre-painted shake-panel products in which the shake-panels are painted or stained at a manufacturing site before they are shipped to a distributor and installed. The shake-panels are painted or stained in a manner in which particles or dust remaining on the cut shake-panels can foul the paint and/or the painting equipment. This can increase maintenance costs and downtime for the painting equipment and reduce the quality of the finished coat of paint. The cutting blades  56 ,  64  and  64   a  illustrated in  FIGS. 2 and 3  produce good quality edges along the slots without creating nearly as much dust as a rotating abrasive disc, but these blades nonetheless produce a small amount of dust that sticks to the shake-panels and subsequently fouls the painting equipment used to pre-paint the shake-panels. Therefore, PacTool International also sought to develop an improved cutting machine that could produce fiber-cement shake-panels suitable for pre-painting operations. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is an isometric view of a prior art fiber-cement shake-panel. 
           [0009]      FIG. 2  is a side view of a prior art cutting machine for forming the shake-panel of  FIG. 1  from cured fiber-cement panels and/or planks. 
           [0010]      FIG. 3  is an isometric view of a prior art slot cutting assembly for forming slots in cured fiber-cement planks or panels. 
           [0011]      FIG. 4A  is an isometric view of a cutting blade or knife for cutting slots in cured fiber-cement panels and/or planks in the manufacturing of fiber-cement shake-panels in accordance with an embodiment of the disclosure. 
           [0012]      FIG. 4B  is a side view of the cutting blade of  FIG. 4A  and an anvil plate of a fiber-cement cutting machine in accordance with an embodiment of the disclosure. 
           [0013]      FIG. 4C  is an end view of the cutting blade and anvil plate shown in  FIG. 4B . 
           [0014]      FIGS. 4D-4G  are side views of cutting blades in accordance with other embodiments of the technology. 
           [0015]      FIG. 5  is an isometric view of a cutting machine for, forming fiber-cement shake-panels in accordance with an embodiment of the disclosure. 
           [0016]      FIG. 6  is an isometric view showing a portion of the cutting machine of  FIG. 5  in more detail. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    The following disclosure describes cutting machines and methods for cutting cured fiber-cement materials to form shake-panels or other fiber-cement products. Many specific details of certain embodiments are set forth in the following description and in  FIGS. 4A-6  to provide a thorough understanding of such embodiments. One skilled in the art, however, will understand that the invention may have additional embodiments, or that the invention may be practiced without several of the details described below. In the figures and description that follow, like elements and features are identified by like reference numerals. Additionally, the sizes and relative positions of elements in the drawings may not necessarily be drawn to scale. For example, unless otherwise expressly described in the text, the shapes, angles or dimensions of various elements are not drawn to scale, and some of these elements are arbitrarily enlarged to improve the legibility of the drawings. Further, unless expressly stated in the text, the particular shapes of the elements as drawn are not intended to convey any information regarding the actual shape of the particular elements, and have been selected for ease and recognition throughout the figures. 
         [0018]    Reference throughout this specification to “one example,” “an example,” “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the example or embodiment is included in at least one example of the present technology. Thus, occurrences of the phrases “in one example,” “in an example,” “one embodiment,” or “an embodiment” in various places throughout this specification are not necessarily all referring to the same example or embodiment. Furthermore, the particular features, structures, routines, steps, or characteristics may be combined in any suitable manner in one or more examples or embodiments of the technology. The headings provided herein are for convenience only and are not intended to limit or interpret the scope or meaning of the claimed technology. 
         [0019]      FIG. 4A  is an isometric view of a cutting blade  100  in accordance with an embodiment of the technology. In this embodiment, the cutting blade  100  includes a head  102  having holes  103   a  and slots  103   b  configured to reversibly attach the blade  100  to a blade mount as explained in more detail below with reference to  FIG. 5 . The cutting blade  100  further includes a channel  104  and a shank  106 . The channel  104  is thinner than the shank  106  so that the blade  100  does not contact the workpiece when the blade  100  is in a lowered position. The shank  106  further includes an inclined edge  107  that extends at an angle α relative to an axis parallel to a cutting path S. The cutting blade  100  can optionally include a hardened cutting element  108  either attached to or integral with the shank  106 . The cutting element  108  has a cutting edge  109  inclined at the angle α and extending at the angle α all the way from a first end  111  to a second end  112 . The cutting element  108  can also have a piercing portion  115 , such as a sharp tip or edge, at the lowermost extent of the cutting edge  109  and sidewalls  114 . In other embodiments, the cutting edge  109  can be at the inclined edge of the shank  106 , and thus the cutting edge  109  can have sidewalls defined by either the sidewalls of the cutting element  108  or the sidewalls of the shank  106  depending on which of these features initially engages the workpiece W. 
         [0020]      FIGS. 4B and 4C  are side and end views, respectively, of the cutting blade  100 , an anvil plate  200 , and a fiber-cement workpiece  250 .  FIGS. 4A and 4B  further illustrate the operation of the cutting blade  100  to form a slot  252  ( FIG. 4C ) in the fiber-cement workpiece  250  by moving the cutting blade  100  along a straight cutting path S between a raised position and a lowered position. Referring to  FIG. 4B , the blade  100  is in the raised position above the anvil plate  200  and aligned with a slot  210  in the anvil plate  200 . The slot  210  includes a first end wall  211  having a first clearance C 1  relative to the first end  111  of the cutting element  108  (e.g., the first end of the cutting edges  109 ) and a second end wall  212  having a clearance C 2  relative to the second end  112  of the cutting element  108  (e.g., the second end of the cutting edges  109 ). Referring to  FIG. 4C , the slot  210  in the anvil plate  200  can further include sidewalls  213  having a clearance C 3  relative to sidewalls  113  of the shank  106  and/or sidewalls  114  of the cutting element  108 . 
         [0021]    In operation, a fiber-cement workpiece  250  is positioned under the blade  100  and over the slot  210  when the blade  100  is in the raised position shown in  FIG. 4B . An actuator (not shown in  FIGS. 4A and 4B ) drives the blade  100  downward so that the piercing portion  115  of the cutting element  108  pierces the fiber-cement workpiece  250  and the cutting edge  109  slices through the workpiece along the longitudinal dimension of the slot  210  to form the slot  252  in the workpiece W. Referring to  FIG. 4C , the blade  100  moves downwardly along the straight cutting path S until the channel  104  is aligned with workpiece  250 . The workpiece  250  can then be moved in a direction D L  along the longitudinal dimension of the slot  210  until the workpiece  250  clears the blade  100 . The blade  100  is then raised along the straight path S to the raised position illustrated in  FIG. 4B  to cut another workpiece. The channel  104  enables the workpiece W to be removed from the cutting area and the blade  100  to be raised to the raised position without passing the shank  106  or cutting element  108  upwardly through the slot  252  formed in the workpiece W. This eliminates delamination that could otherwise be caused by moving the cutting element  108  or shank  106  upwardly through the slot  252 . 
         [0022]    In a specific embodiment of the blade  100  illustrated in  FIGS. 4A-C , the angle α is from approximately 83.5° to approximately 85°. Although this angle is relatively shallow with respect to the surface of the workpiece  250 , it produced a much cleaner cut with far fewer cracks along the cut slot  252  compared to a test blade having an angle α of 78°. Using an angle α of approximately 83.5° to approximately 85° also produced less dust compared to blades with lower angles (i.e., steeper incline relative to the surface of the workpiece  250 ). The embodiment of the blade  100  having an angle α of approximately 83.5° to approximately 85° is accordingly well-suited for cutting slots in fiber-cement workpieces to form shake-panels that are prepainted at a manufacturing facility before being shipped to a distributor. 
         [0023]    A specific embodiment of the blade  100  and the anvil plate  200  shown in  FIGS. 4A-C  has end clearances C 1  and/or C 2  of approximately 0.005-0.015 inch and side clearances C 3  on each side of approximately 0.008-0.020 inch. The end clearances C 1  and C 2  are preferably 0.010 inch for cured fiber-cement workpieces that have a low moisture content and a nominal thickness of 0.25 inch. The side clearances C 3  between the sidewalls  114  of the cutting element  108  are preferably 0.015-0.018 inch, and in particular 0.017 inch, for cutting a cured fiber-cement workpiece having a low moisture content and a nominal thickness of 0.25 inch. The end clearance of 0.010 inch and the side clearance of 0.17 inch provide excellent edge quality along the slot  252  formed in a cured fiber-cement workpiece with a nominal thickness of 0.25 inch that further enhances the appearance and reduces the amount of dust. Even a modest difference in the side clearance C 3  to 0.020 inch causes a significant degradation of edge quality along the slot  252  that may render the shake-panels with such slots unsuitable for prepainting. 
         [0024]      FIGS. 4D-4G  illustrate additional embodiments of cutting blades  100 . As opposed to the cutting edge  109  extending at the angle α all the way from the first end  111  to the second end  112  as shown in  FIGS. 4A-4C , other embodiments of the cutting edge  109  can be curved and or extend at a different angle for a portion of its length. For example, the cutting edge  109  can have a single curve of either a single radius or more generally a compound radius (shown in  FIG. 4D ), or the cutting edge  109  can extend at a first angle from the first end  111  to an intermediate point P i  and then a second angle from the intermediate point P i  to the second end  112 .  FIGS. 4F and 4G  show cutting blades  100  with double cutting edges  109   a  and  109   b  that extend from a piercing portion  115  located between the first and second ends  111  and  112 . In  FIG. 4F  the double cutting edges  109   a  and  109   b  are straight edges, whereas in  FIG. 4G  the double cutting edges  109   a  and  109   b  are curved. The cutting element  108  is optional, and thus the cutting edges  109 ,  109   a  and  109   b  shown in  FIGS. 4A-4G  can be part of the shank  106  as shown in  FIGS. 4D-4G  or the cutting element  108  attached to the shank  106  as shown in  FIGS. 4A-4C . 
         [0025]      FIG. 5  is an isometric view illustrating a cutting machine  500  for forming fiber-cement shake-panels or other fiber-cement products from cured, low moisture content fiber-cement planks and panels. The cutting machine  500  includes a frame  510 , a plurality of rollers  512  and belts  514  that individually and/or together drive a workpiece through the cutting machine  500 , and a cutting assembly  520 . The cutting assembly illustrated in  FIG. 5  includes a cross member  522 , blade mounts  524  projecting from the cross member  522 , actuators  526  attached to the cross member  522 , and end guides  528  that guide the cross member  522  along a straight path S. The cutting assembly  520  can further include press down rollers  529  that move with the cross member  522  and blade mounts  524 . The cutting machine  500  can further include an anvil plate  530  having a plurality of slots  532  corresponding to the blade mounts  524 . The blades are not mounted to the blade mounts  524  in the embodiment of the cutting machine  500  illustrated in  FIG. 5 . In operation, the actuators  526  drive the cross member  522  downwardly along the straight path S between a raised position and a lowered position. 
         [0026]      FIG. 6  is an isometric view illustrating a portion of the cutting assembly  500  illustrated in  FIG. 5  with an embodiment of the blades  100  illustrated in  FIGS. 4A-C . In the embodiment illustrated in  FIG. 6 , the blades  100  are mounted to the blade mounts  524  such that the first end  111  of the cutting element  108  of one blade and the second end  112  of the cutting element  108  of the another blade face in the same direction. As a result, the cutting edges  109  of the two blades project downwardly in opposite directions along the Y-axis. This configuration of attaching the blades  100  to the blade mounts  524  causes equal and opposite forces along the Y-axis as the blades  100  move through the fiber-cement workpiece, which inhibits the workpiece from moving along the Y-axis during the cutting process. This becomes more important with the close tolerances between the cutting element  108  and the slots  532 . In other embodiments, the blades  100  can be attached to the blade mounts  524  such that the cutting edges  109  all slope downwardly in the same direction relative to the Y-axis. In still a different embodiment, blades that are not adjacent to each other can be mounted in a reverse configuration similar to the embodiment illustrated in  FIG. 6 . 
         [0027]    The blades  100  can be attached to the blade mounts  524  using shims to adjust the position of the blades  100  along the X-axis. This allows the blades  100  to be accurately aligned with corresponding slots  532  in the anvil plate  530  within the tight tolerances required to cut the fiber-cement panels and planks in a highly dust-free manner. Moreover, the combination of the holes  103   a  and slots  103   b  in the head  102  of each blade  100  enables the blades  100  to be attached the blade holders  524  in either the forward or reversed position relative to the Y-axis. The slots  103   b  further allow adjustment along the Y-axis to aligned the ends of the blades  100  with the ends of the slots  532  in the anvil plate  530 . 
         [0028]    The blades  100  illustrated in  FIG. 6  also provide good, square corners at the closed or blind end of the slots cut through the workpiece. By providing a hard, sharp cutting element  108  that can withstand the abrasiveness of cured fiber-cement, the closed end of the slots can have highly squared corners. This improves the appearance of the slots and appears to reduce the particles or dust that remain on the workpiece after passing through the cutting machine. 
         [0029]    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. For example, although the blades and cutting assemblies described above are very well suited for cutting slots in cured, low moisture fiber-cement panels, they can also be used to form slots in uncured or partially cured pieces of fiber-cement that have higher moisture content. Accordingly, the invention is not limited except as by the appended claims.