Patent Publication Number: US-2018050465-A1

Title: Carbide insert mechanical clamp feed roller

Description:
FIELD OF THE INVENTION 
     This invention generally relates to a feed roller head and more specifically to a system and method for using a feed roller head to shift a work piece in a predetermined direction. 
     BACKGROUND OF THE INVENTION 
     Typically, saw-teeth are required on the feed roller heads used in lumber mills in order that cants (or squared-off logs which have two opposed planar surfaces) may be securely gripped for accurately positioned feeding into a band saw or saw cluster. 
     At present, in commercial operations, the saw-teeth are available in short strips of the various lengths. One or more strip lengths, depending on the length of the feed roller head, are forced into a tight-fitting groove in the body of the feed roller head by hammering or pinch clamping. The saw-teeth become blunted and ineffective after about six months to a year&#39;s use and require replacement. 
     In order to replace the worn saw-teeth, it is necessary to first remove the feed roller head from the machine. The technique for removing the inserts involves manually (or less commonly, pneumatically) chiseling the inserts out of the groove. Manual chipping is slow and inflicts damage to the groove. Pneumatic removal poses potential hazards to the operators due to the danger of flying metal fragments. Replacement of an insert can only be conducted by the conventional manual technique about three times before excessive damage to the groove has resulted. Usually at this point the saw-teeth strips are welded into the groove, for a final usage and upon dulling of these welded teeth the whole feed roller head usually is discarded. 
     Feed roller heads having are well known, as exemplified, by U.S. Pat. App. No. 2015/0210474 teachings a tapered feed roller head; U.S. Pat. No. 4,509,574 that teaches an improvement in a debarking machine wherein feed roll spikes having plus-shaped cutting edges are provided; and U.S. Pat. No. 4,385,650, which describes an improved feed roller head for logs that has a plurality of radially extending trapezoidally shaped pyramids spaced circumferentially about the surface. 
     However, there still exists the need for a feed roller head having a gripping insert that is more durable, can be easily replaced to extend the usable life of the feed roller head, and replacement of the gripping insert is speedier and less labor intensive. The invention provides such a feed roller head. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein. 
     BRIEF SUMMARY OF THE INVENTION 
     In one aspect the invention provides a system for working on a work piece having a feed roller having a feed roller head. The feed roller head having a body including at least one gripping insert and at least one clamping element for clamping at least one gripping insert to the body of the feed roller. The feed roller head having a rotary axis. The feed roller is capable of shifting a workpiece in a predetermined direction when the at least one gripping insert contacts the work piece and the feed roller head is rotated about its rotary axis. The system further comprising a machining system downstream of said feed roller having a machining element capable of working on the work piece being fed in the predetermined direction by the feed roller head. 
     In another aspect the system has a helical gripping insert is made from carbide. 
     According to another aspect the machining element of the system is a cutting tool capable of cutting the work piece. 
     According to another aspect the feed roller head in the system can shift the work piece in the predetermined direction between 50 feet per minute and 400 feet per minute. 
     In yet another aspect, the feed roller head in the system rotates about the rotary axis between 1 and 100 rotations per minute. 
     According to one aspect the work piece processed in the system is a piece of wood. 
     In another aspect the clamping element of the feed roller head used in the system is coupled to the feed roller head by a compound screw. 
     In yet another aspect a feed roller head having a feed roller body configured to rotate in a predetermined direction about an axis of rotation. The feed roller head having at least on clamp arranged to provide support along a helical path. The feed roller head having a helical slot formed by the combination of the feed roller body and the at least one clamp along the helical path. The slot having a front wall formed by the feed roller body and a rear wall formed by the at least one clamp and the front wall is forward of the rear wall relative to the predetermined direction. The feed roller head having a helical gripping insert clamped into the slot by the at least one clamp. 
     According to another aspect the feed roller head has a helical gripping insert is made from carbide. 
     In yet another aspect the clamp comprises a plurality of clamping wedges residing in a helical channel defined by the feed roller body. 
     According to one aspect the multiple helical channels clamping wedges and helical gripping inserts are arranged at different angular positions about the axis of rotation. 
     In yet another aspect a second helical gripping insert is clamped into a second slot by the clamp. 
     According to another aspect the second slot is formed by a combination of the feed roller body and the at least one clamp along the helical path, the second slot having a rear wall formed by the feed roller body and a front wall formed by the at least one clamp, wherein the front wall is forward of the rear wall relative to the predetermined direction. 
     In yet another aspect, the body of the feed roller head has a connection portion to connect with a feed roller of a machining system. 
     According to yet still another aspect, the connection portion of the feed roller head is a through bore. 
     According to yet another aspect a method including powering a feed roller causing at least one feed roller head to rotate about its rotary axis. Placing the work piece on the feed roller such that it comes into contact with at least one gripping insert coupled to the feed roller head. Shifting the work piece a predetermined direction toward the machining system through contact with the gripping insert. Releasing the work piece from the gripping insert of the feed roller head such that the work piece shifts the predetermined direction and is completely received by the machining system. Processing the work piece through the machining system. 
     According to yet another aspect a method of advancing sheet material including engaging the sheet material with a feed roller. The feed roller having a feed roller head having a body. The feed roller head includes at least one gripping insert and at least one clamping element for clamping the at least one gripping insert to the body of the feed roller. Rotating said feed roller head about a rotary axis and feeding the sheet material in a predetermined direction with the at least one gripping insert contacting the work piece during said rotating. 
     According to another aspect a method where the sheet material is a wood material, and wherein the gripping insert indents the wood material leaving an indentation. 
     According to yet another aspect a method where the indentation is between 0.1 millimeter and 2 millimeter deep. 
     In yet another aspect a method including machining a layer from the wood material and removing the indentation during machining. 
     According to another aspect a method where the machining comprises utilizing a rotating cutter having a plurality of knives disposed about a cutter body, and during an operation mode, the feed roller is operated at a rotational speed of between 1 and 100 rpm; and wherein the rotating cutter is operated at a rotational speed of between 3,000 rpm and 12,000 rpm. 
     According to another aspect a plurality of gripping inserts and a plurality of the clamping elements are provided at a regular angular spacing around the body of the feed roller. The regular angular spacing is provided such that at least one of the gripping inserts is in contact with the sheet material at all times to ensure continuous feeding of the sheet material. 
     Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings: 
         FIG. 1  is an isometric view of a feed roller head having a gripping insert having a helical shape and made of carbide in accordance with a preferred embodiment of the present invention; 
         FIGS. 2 and 3  are side and end views of the feed roller head shown in  FIG. 1 , respectively; 
         FIG. 4  is an enlarged partial end view of the feed roller head shown in  FIG. 1 , illustrating the securement of the gripping insert; 
         FIGS. 5 and 6  are side and end views of the gripping insert for use in the feed roller head shown in  FIG. 1 , respectively; 
         FIG. 7  is a cross-section of the gripping insert shown in  FIGS. 5 and 6 ; 
         FIG. 8  is an isometric view of one of the clamping wedges as used in the feed roller illustrated in  FIG. 1 ; 
         FIGS. 9, 10, and 11  are plane, side and end views of the clamping wedge shown in  FIG. 8 , respectively, with hidden lines showing threaded hole and profile details; 
         FIG. 12  is a cross-sectional illustration of the feed roller head detail shown in  FIG. 4 ; 
         FIG. 13  is a perspective side-view of a system for shifting a work piece incorporating the feed roller head illustrated in  FIG. 1  and a machining system to process the work piece; 
         FIG. 14  is a partial perspective view of the feed roller head showing an exploded view of one set of gripping inserts, clamping wedges, and compound screws removed from a helical channel of the feed roller head. 
     
    
    
     While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , a feed roller head  10 , having a first helically shaped gripping insert  12  and a second helically shaped gripping insert  12 ′ in accordance with one aspect of the present invention is illustrated. The feed roller head  10  is used to grip a work piece and then shift the work piece a predetermined distance and direction. 
     The feed roller  102  has a motor  108  (see  FIG. 13 ) that drives the feed roller head  10  about an axis of rotation  14  (see  FIG. 3 ) in a predetermined direction  38 . The feed roller head  10  has a connection portion  13 . The connection portion  13  provides a means for the feed roller head  10  to connect to a feed roller  102  of a machining system  100  (see  FIG. 13 ). In a preferred embodiment, the connection portion  13  is a through bore that extends axially through the body  16  of the feed roller head  10  along the axis of rotation  14  (see  FIG. 3 ). However, as will be understood by one having ordinary skill in the art, the connection portion  13  of the feed roller head  10  is not limited to being a through bore and the feed roller head  10  may connect with the feed roller  102  by any means generally known in the art. 
     As illustrated, the feed roller head  10  is configured to rotate in a single predetermined direction  38  about the axis of rotation  14 . The direction of rotation for the disclosed embodiment, as viewed in  FIG. 3  and indicated by arrow  38 , is counter-clockwise about the axis of rotation  14 . 
     As shown in  FIG. 1 , the feed roller head  10  of the present invention generally includes a feed roller body  16 , gripping inserts  12 ,  12 ′ and a plurality of clamping wedges  18 . The gripping inserts  12 ,  12 ′ provide gripping edges  20  for the feed roller head  10  and are secured to the feed roller body  16  by a plurality of clamping wedges  18 . In a preferred embodiment, the gripping inserts  12 ,  12 ′ are manufactured from carbide and the feed roller body  16  and clamping wedges  18  are manufactured from steel. The gripping inserts  12 ,  12 ′ are wedged between a portion of the feed roller body  16  and the clamping wedges  18 . Embodiments of the feed roller head  10  may include any number of gripping inserts  12 ,  12 ′, but typically more than one, and typically with a balanced orientation (e.g. the gripping inserts  12 ,  12 ′ being equally spaced apart at angular intervals). Further, typically embodiments of the feed roller head  10  will space the gripping inserts  12 ,  12 ′ such that at least one of the gripping insert  12 ,  12 ′ is in contact with the work piece until the work piece has been shifted off of the feed roller head  10  in the predetermined direction  112  (see  FIG. 13 ). 
     As is best illustrated with reference to  FIGS. 1-4, 12, and 14  the outer periphery  22  of the feed roller body  16  includes helical channels generally indicated at  24 . The channels  24  provide a first area/void for receiving the clamping wedges  18  and the gripping inserts  12 ,  12 ′. The first area/void of the channel  24  includes a leading wall  26  and a trailing wall  28  extending radially inward. The leading wall  26  is forward of the trailing wall  28  relative to the predetermined direction of rotation  38  of the feed roller head  10 . In addition, the leading wall  26  extends along a helical path that is substantially parallel to a helical path of the trailing wall  28 . 
     Further, the channels  24  provide a second area/void for partially receiving the clamping wedges  18 . The second area/void of the channel  24  includes a second leading wall  33  and a second trailing wall  35  extending radially inward. The second leading wall  33  is forward of the second trailing wall  35  relative to the predetermined direction of rotation of the feed roller head. In addition, the second leading wall  33  extends along a helical path that is substantially parallel to a helical path of the second trailing wall  35 . 
     As shown in  FIG. 2 , the helical channels  24  extend between opposed axial ends  32  and  34  of the feed roller body  16 . The helical channels  24  also extend angularly about the axis of rotation  14  of the feed roller head  10 . The helical shape is preferably configured with respect to the predetermined direction of rotation  38 . Specifically, the helical channels  24  preferably coil about the axis  14  in a direction opposite the predetermined direction of rotation  38 . In the illustrated embodiment, the feed roller head  10  is designed to rotate counter-clockwise (see arrow  38  in  FIG. 3 ). As a result, the helical channels  24  extend angularly in the opposite clockwise direction, indicated by arrow  39 , when moving in an axial direction from the distal  32  end to the connection end  34 . Conversely, if the feed roller head  10  is designed to rotate clockwise, when viewed up the axis of rotation  14  from the distal end  32  to connection end  34 , the helical channels  24  would preferably extend angularly in the counter-clockwise direction. 
     At least one clamp and preferably multiple clamps in the form of clamping wedges  18  secure the gripping inserts  12 ,  12 ′ within the helical channel  24 . The gripping inserts  12 ,  12 ′ have a helical shape and extend along a helical path. In a preferred embodiment, the gripping inserts  12 ,  12 ′ are manufactured from carbide. As best illustrated with reference to  FIGS. 1 and 2 , the helical path and contour of the gripping inserts  12 ,  12 ′ are the same as the helical path and contour of the helical channel  24 . 
     The gripping insert  12  is secured and locked to the feed roller body  16  by being wedged in a first slot  76 . In the illustrated embodiment the first slot  76  is defined between the leading wall  26  of the helical channel  24  and the front face/wall  54  of the clamping wedges  18  collectively. The gripping inset  12 ′ is secured and locked to the feed roller body  16  by being wedged in a second slot  77  that is defined between the trailing wall  28  of the helical channel  24  and the rear face/wall  56  of the clamping wedges  18  collectively. 
     The first receiving slot  76  and the second receiving slot  77  are wider radially inward towards the axis of rotation  14 . Furthermore, the width of a radially outer portion of the first receiving slot  76  and the second receiving slot  77  are narrower than the width of the bottom  62  of the respective gripping inserts  12 ,  12 ′ inserted in the first and second receiving slots  76 , 77 . By having the gripping inserts  12 ,  12 ′ with a wider bottom  62  than a radially outer portion of their respective first receiving slot  76  and second receiving slot  77 , the clamping wedges  18  act to positively lock the gripping inserts  12 ,  12 ′ in the radial direction. This inward positive locking arrangement opposes centrifugal forces applied to the gripping inserts  12 ,  12 ′ resulting from high speed rotation of the feed roller head  10  during use. 
     Best illustrated with reference to  FIGS. 5 and 7 , the leading face  42  of the first gripping inserts  12 ,  12 ′ have a top edge  90 , which provides the gripping edge  20 . As shown in  FIG. 4 , the leading face  42  of the first gripping insert  12  abuts with the leading wall  26  of the helical channel  24  at interface  50 . A trailing face  52  (see  FIGS. 6 and 7 ) of the first gripping insert  12  abuts with a front face  54  of the clamping wedge  18  at interface  58  (see  FIGS. 4 and 12 ). Likewise, the leading face  42  of the second gripping insert  12 ′ abuts the trailing face  56  of the clamping wedge  18  at interface  59  and the trailing face  52  of the second gripping insert  12 ′ abuts the trailing wall  28  of the helical channel  24  at interface  51 . 
     In accordance with an aspect of the present invention, the clamping wedges  18  are located between the gripping inserts  12 ,  12 ′. Further, in accordance with another aspect of the present invention, the top surface  19  of the clamping wedge  18  is located radially inward of the top surface  90  of the gripping inserts  12 ,  12 ′ relative to the axis of rotation  14  of the feed roller head  10 . Importantly, this helps to protect the clamping wedges  18  by preventing the top surface  19  of the clamping wedges  18  from making unnecessary contact with the work piece that is being shifted, which can lead to wearing of the clamping wedges  18 . 
     Each of the clamping wedges  18  are threadedly secured to the feed roller body  16  by a fastener that may take the form of a compound screw  66 , as illustrated in  FIG. 12 . The compound screw  66  includes a tool engagement socket  68 , illustrated by dashed lines, for engaging the compound screw  66 . For example, the tool engagement socket  68  may be a hex socket for receipt of and engagement with an Allen wrench (not shown). The compound screw  66  is a screw that has both a portion of left handed threads  70  and a portion of right handed threads  72  about the same axis of rotation. The left handed threads  70  threadedly engage an internally threaded bore  73  of the clamping wedge  18 , and the right handed threads  72  engage an internally threaded bore  74  of the feed roller body  16 . Thus, as the compound screw  66  is turned, it concurrently threads into or out of both the clamping wedge  18  and the feed roller body  16 . 
     As the compound screw  66  is concurrently threaded into the clamping wedge  18  along a bottom surface  34  of the helical channel  24  of the feed roller body  16 , the clamping wedge  18  is tightened, and specifically, drawn radially inward and towards the feed roller body  16  and into the helical channel  24 . The clamping wedge  18  in combination with the helical channel  24  form the first receiving slot  76  between the leading wall  26  of the helical channel  24  and the front face  54  of the clamping wedge  18  where the gripping insert  12  can at least partially rest on bottom surface  27  of the helical channel  24 . Likewise, the clamping wedge  18  in combination with the helical channel  24  form a second receiving slot  77  between the trailing wall  28  of the helical channel  24  and the rear face  56  of the clamping wedge  18  where the gripping insert  12 ′ can at least partially rest on bottom surface  29  of the helical channel  24 . 
     The first receiving slot  76  and the second receiving slot  77  are helical having the same helical shape and contour as the helical channel  24  and the gripping insert  12 . With the clamping wedges  18  aligned sided by side and secured to the feed roller body  16  within the helical channel  24 , as illustrated in  FIGS. 1 and 2 , the first receiving slot  76  and the second receiving slot  77  extend between opposed ends  32  and  34  of the feed roller body  16 . To establish the helical path, each clamping wedge  18  is partially angularly offset from one another in the angular direction  39  of the helical path about axis of rotation  14 . Furthermore, the leading faces  54  of the clamping wedges  18  that provide support for the gripping insert  12  are configured such that there is a smooth transition from one clamping wedge  18  to the next and the trailing face  52 , and consequently, the gripping insert  12 , is fully supported by the clamping wedges  18  collectively. Likewise, the trailing faces  56  of the clamping wedges  18  that provide support for the gripping insert  12 ′ are configured such that there is a smooth transition from one clamping wedge  18  to the next and the leading face  42 , and consequently, the gripping insert  12 ′, is fully supported by the clamping wedges  18  collectively. 
     The leading wall  26  of the helical channel  24  and the leading face  54  of the clamping wedge  18  cooperate and co-act to secure the gripping insert  12  illustrated in  FIG. 7 . Likewise, the trailing wall  28  of the helical channel  24  and the trailing face  56  of the clamping wedge cooperate and co-act to secure the gripping insert  12 ′. 
     During assembly, the clamping wedge  18  is tightened down causing it to wedge between the trailing face  52  of the first gripping insert  12  and the leading face  42  of the second gripping insert  12 ′. As the clamping wedge is wedged against the trailing face  52  of the first gripping insert  12  it imparts a tangential load on the gripping insert  12  that presses the leading face  42  of the gripping insert  12  against the leading wall  26  of the helical channel  23 . Likewise, as the clamping wedge  18  is wedged against the leading face  42  of the second gripping insert  12 ′ it imparts a tangential load on the second gripping insert  12 ′ that presses the trailing face  52  of the second gripping insert against the trailing wall  28  of the helical channel  24 . The tangential load applied to the gripping inserts  12 ,  12 ′ further secures the gripping inserts  12 ,  12 ′ to the feed roller body  16 . 
     When the gripping inserts  12 ,  12 ′ are clamped to the feed roller body  16 , the gripping inserts  12 ,  12 ′ extends radially beyond a portion of the outer periphery  22  of the feed roller body  16 , as shown in  FIG. 4 . This ensures that both the outermost radial path  91  of the gripping inserts  12 ,  12 ′ and the innermost radial path  93  of the gripping inserts  12 ,  12 ′ are able to make strong contact with the work piece to shift the work piece in the predetermined direction  112 , while also preventing the clamping wedges  18  from making inadvertent contact with the work piece, which could cause damage to the clamping wedges  18  or cause the clamping wedges  18  to loosen. 
     As best illustrated in  FIGS. 4 and 7 , the gripping insert  12  has a tapered outer peripheral surface  90  to better define the gripping edge  20  for engagement with the work piece. By having the outer surface  90  canted away from the gripping edge  20  from an outermost radial path  90  to an inner most radial path  93  of the outer surface  90 , relative to the axis of rotation  15 , it allows the gripping edge  20  to rotate about the outermost radial path  91  of the assembled feed roller head  10 . The radially inward tapering of the outer peripheral surface  90  from the outermost radial path  91  to the innermost radial path  93  also acts help the gripping inserts  12 ,  12 ′ to make strong contact with the work piece while at the same time allowing the work piece to release from the gripping inserts  12 ,  12  after the gripping inserts  12 ,  12 ′ has shifted the work piece in the predetermined direction  112 . 
     Turning to  FIG. 13 , a machining system  100  employs a feed roller  102  using feed roller heads  10 , to shift a piece of lumber or work piece  106 , in a predetermined direction  112 . The feed roller heads  10  are coupled to the feed roller  102  via the connection portion  13  of the feed roller heads  10  (see  FIGS. 1 and 3 ). The feed roller heads  10  can rotate about their axis of rotation  14  (see  FIG. 3 ) in a predetermined direction  38  that correspond with the predetermined direction  112  that the piece of lumber or work piece  106  is to be shifted. 
     In use, the feed roller heads  10  rotate about their axis of rotation  14  (see  FIG. 3 ) in the predetermined direction  38 . The feed roller heads  10  then contact the piece of lumber or work piece  106  with their gripping inserts  12 ,  12 ′ that shift the piece of lumber or work piece  106  in the predetermined direction  112 . The feed roller heads  10  will continue to rotate in the predetermined direction  38  and the gripping inserts  12 ,  12 ′ will continue to contact the piece of lumber or work piece  106  causing it to shift in the predetermined direction  112  until the piece of lumber or work piece  106  is fully inserted into the processing system  104 . 
     In the illustrated embodiment, the processing system  104  consists of a cutting tool  105 , which can be for example a band saw or cluster saw. The feed roller  102  has a motor  108  and belts  109  and  111  to rotate the feed roller heads  10  in a predetermined direction  38  that correspond with the predetermined direction  112  that the piece of lumber or work piece  106  needs to be shifted. 
     Further, it should be noted that some processing systems  104  require the feed roller  102  to shift the work piece in the predetermined direction  112  with sufficient force to drive the work piece through the processing system  104 , such as for example, when a feed roller head  10  is required to shift a piece of lumber or work piece  106  in a predetermined direction  112  as the piece of lumber or work piece  106  is ripped by a cutting tool  105 , such as a band saw or cluster saw. 
     According to one embodiment, it is envisioned that the feed roller head  10  can rotate between 1 and 100 rotations per minute. 
     According to another embodiment, it is envisioned that the feed roller head  10  can shift a work piece in a predetermined direction  112  between 50 and 400 feet per minute. 
     According to another embodiment, it is envisions that the gripping inserts  12 , 12 ′ can indent a piece of lumber or work piece  106 , such as a sheet material, such that the piece of lumber or work piece  106  is left with an indentation. 
     In yet another embodiment, it is envisioned that the indentation left in the lumber or work piece  106 , such as a sheet material, by the gripping inserts  12 , 12 ′ can be between 0.1 millimeter and 2 millimeter deep. 
     In yet another embodiment, it is envisioned the processing system  104  can machine a layer from the piece of lumber or work piece  106 , such as a sheet material, to an indentation made in the piece of lumber or work piece  106 , such as a sheet material, by the gripping inserts  12 , 12 ′ during machining. 
     According to another embodiment the processing system  104  utilizes a cutting tool  105 , such as a rotating cutter having a plurality of knives disposed about the rotating cutter. 
     According to another embodiment, it is envisioned that the cutting tool  105 , such as a rotating cutter having a plurality of knives disposed about the rotating cutter, can operate at a rotational speed of between 3,000 rpm and 12,000 rpm. 
     According to another embodiment, it is envisioned that in operation the feed roller head  10  can have a rotational speed of between 1 and 100 rpm. 
     According to another embodiment, it is envisioned that gripping inserts  12 , 12 ′ and clamping elements, such as clamping wedges  18 , are provided at a regular angular spacing around the body  16  of the feed roller head  10 . The regular angular spacing of the gripping inserts  12 , 12 ′ and the clamping elements, such as clamping wedges  18 , allow for at least one of the gripping inserts  12 , 12 ′ to be in contact with a piece of lumber or work piece  106 , such as a sheet material, at all times to ensure continuous feeding of the piece of lumber or work piece  106 , such as a sheet material. 
     All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
     Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context