Abstract:
A method and apparatus for selecting random length boards for nesting into a single row of predetermined lengths includes the initial step of arranging a plurality of random length boards on an accumulating rack. A plurality of the boards are then conveyed to channels in an adjacent storage rack. The length of each board is determined as the board is conveyed from the accumulating rack to the storage rack, and this information is transmitted to a central processor. The processor calculates combinations of board lengths in the storage rack which will form a single stock row having a combined board length within a predetermined target range. The processor then selects a preferred combination of boards from the possible combinations, and activates gates in the channels to drop the boards to a conveyor and move the selected boards to a stock row accumulating location. The processor then activates gates on the accumulating rack tracks to convey additional boards to empty channels in the storage rack, and repeats the process. The apparatus includes an accumulating conveyor with longitudinal tracks positioned adjacent a storage rack with longitudinal channels aligned with the tracks. A scanning assembly is positioned between the accumulating conveyor and storage rack for scanning boards moving between the conveyor and storage rack, to determine the length of each board. The central processor is connected to the scanning assembly, and gates on the accumulating rack and storage rack, to automatically operate the system.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
         [0001]    (Not applicable)  
         STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT  
         [0002]    (Not applicable)  
         BACKGROUND OF THE INVENTION  
         [0003]    (1) Field of the Invention  
           [0004]    The present invention relates generally to apparatus for selecting random length materials, such as wood flooring stock and bundling nested combinations into a standard length, and more particularly to an improved apparatus for automated sorting of a plurality of random length stock into standard length combinations for bundling.  
           [0005]    (2) Background Information  
           [0006]    Solid wood flooring is typically produced in random lengths which vary from nine inches to eight feet long. The length is determined by cuts made to remove randomly placed defects in the natural raw material.  
           [0007]    The flooring stock is typically shipped in standard bundles ranging from seven to eight feet long, and therefore the flooring stock is conventionally bundled in one of two ways: (1) sorting by length to the nearest even foot in length, with various length bundles included on a single pallet; and (2) nesting various lengths of wood stock into a standard bundle, typically seven to eight feet long. In either case, the top layer of flooring in each bundle is inverted, so that the face of the product is protected from damage during shipping and handling.  
           [0008]    Nesting is becoming the preferred method of bundling, because it is easier to handle and ship and typically assures a random assortment of lengths for the installer.  
           [0009]    The most popular method for assembling random length wood flooring into nested bundles uses people to manually assemble the bundles. Generally, a person will first determine the grade of the flooring board by visual inspection. The inspected stock is then placed into a rack and sorted by its approximate length. A person on the other side of the rack will then remove selected pieces from one or more slots in the rack, visually judging the lengths to make a row of the desired standard length, when the pieces are nested end to end. In this method, the wood stock is generally sorted into approximate one foot increments. However, rarely are the boards exactly cut to the foot, and therefore are either longer or shorter than the increment slot in the rack in which it is placed. For this reason, once a combination of pieces is selected by the person assembling the bundle, it is often necessary to remove and replace various pieces to adjust the overall length of the nested row to fit the predetermined standard.  
           [0010]    On the other hand, if the person grading the stock sorts the stock into racks with smaller increments, the sorting rack must necessarily be larger, and more time must be spent determining the proper slot in the rack for storage, as well as determining appropriate lengths for selection and nesting into the desired predetermined length row.  
           [0011]    In some cases, a separate automated sorting mechanism is used to sort the wood stock by approximate length after grading. However, the nesting process is still currently accomplished manually by people. After enough rows of a proper length have been selected (usually twelve to fifteen rows for standard strip flooring) the top layer of product is manually inverted to protect the upper face of the product. The bundle is then tied together with plastic straps by a banding machine and the bundles are palletized for shipping.  
           [0012]    As each row of nested lengths are assembled into a stack forming a bundle, each row is typically abutted flush, allowing the distal ends of the rows to vary. Thus, the bundle will typically include a proximal end with all rows abutted flush, and a distal end with a “jagged” appearance because of the various completed lengths of rows.  
           [0013]    In an alternative bundling method, each end of the pieces of material are abutted against stops, forming flush ends, with the gaps between nested pieces located in the middle of the bundle. Frequently, the interleaving of the pieces in this particular method is not adequate to hold the bundle together and the bundle is not as secure when bound. This method also makes it more difficult to estimate the total actual footage of the material in the bundle. Because the longest and shortest rows in the bundle are typically four to six inches longer or shorter than the predetermined average, longer pallets are necessary for shipping and storage.  
           [0014]    In forming a “jagged end” bundle, the bundle assembler typically starts with a long piece of wood stock, or a combination of short pieces, and then chooses a short piece that will nest with the initial piece or pieces to approximate the desired predetermined length. This results in most of the short pieces being located at the jagged end of the bundle, which can then be easily dislodged from the bundle during handling and shipping. Frequently, when a truck or container of flooring is opened at its destination, dozens of short pieces of flooring have fallen from the bundles, with no way of determining which piece belongs to which bundle. This in turn results in a shortage of wood product from bundles, to the end user.  
           [0015]    The process of assembling bundles is further complicated by the measuring rules commonly used in this industry. A standard machining or “end matching” allowance of ¾ inch is allowed on each piece of flooring. End matching is the process of putting a groove on one end of a piece of flooring stock and a tongue on the other end. The tongue and groove then interlock to prevent displacement of the ends of the flooring over time. The standard method of measurement for wood flooring calls for the addition of ¾ inch to the length of the face of each piece, in order to allow for the material which is necessarily removed by the end matching process. This means that, if a row is being assembled for a standard length bundle, it may be ¾ inch short if the row consists of one piece of wood stock, 1½ inches short if made up of two pieces of wood stock, etc. In practice, the average length is assumed, and the target bundle length is shortened by the required amount.  
           [0016]    Industry grading rules also require a minimum average length for each grade. The system of the present invention allows the processor to easily keep track of this information.  
           [0017]    The current process of creating nested rows to form bundles by hand is time consuming, tedious, and proficiency requires consider experience. Some bundle assemblers never become good at choosing an acceptable combination of wood stock lengths on the first or second try, and therefore must spend additional time in a trial and error process to form a bundle. Further, the manual process of selecting rows for a bundle is not particularly accurate when assembled by hand, especially if the person assembling the bundle is in a hurry to create the bundle.  
           [0018]    Further, once assembled, it is difficult to obtain an accurate measure of the material which is included in each bundle, especially if the method of forming the bundle with two flush ends is utilized.  
         BRIEF SUMMARY OF THE INVENTION  
         [0019]    It is therefore a general object of the present invention to provide an improved bundling apparatus for selecting random length pieces of product to form standard length bundles.  
           [0020]    Another object is to provide a bundling apparatus which is automated to improve the accuracy of the overall length of rows within a bundle.  
           [0021]    A further object of the present invention is to provide an automated bundling apparatus which is capable of documenting the length of pieces within a bundle more accurately than possible when assembled by hand.  
           [0022]    Yet another object is to provide an automated bundling apparatus in which the number of pieces in a row of a bundle is automatically tracked, to automatically compensate for end matching allowance.  
           [0023]    Still another object is to provide a bundling apparatus which is capable of tracking minimum average length information for each grade of product.  
           [0024]    These and other objects of the present invention will be apparent to those skilled in the art.  
           [0025]    The method and apparatus for selecting random length boards for nesting into a single row of predetermined lengths includes the initial step of arranging a plurality of random length boards on an accumulating rack. A plurality of the boards are then conveyed to channels in an adjacent storage rack. The length of each board is determined as the board is conveyed from the accumulating rack to the storage rack, and this information is transmitted to a central processor. The processor calculates combinations of board lengths in the storage rack which will form a single stock row having a combined board length within a predetermined target range. The processor then selects a preferred combination of boards from the possible combinations, and activates gates in the channels to drop the boards to a conveyor and move the selected boards to a stock row accumulating location. The processor then activates gates on the accumulating rack to convey additional boards to empty channels in the storage rack, and repeats the process. The apparatus includes an accumulating conveyor with longitudinal tracks positioned adjacent a storage rack with longitudinal channels aligned with the tracks. A scanning assembly is positioned between the accumulating conveyor and storage rack for scanning boards moving between the conveyor and storage rack, to determine the length of each board. The central processor is connected to the scanning assembly, and gates on the accumulating rack and storage rack, to automatically operate the system.  
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0026]    The preferred embodiment of the invention is illustrated in the accompanying drawings, in which similar or corresponding parts are identified with the same reference numeral throughout the several views, and in which:  
         [0027]    [0027]FIG. 1 is a top plan view of the bundling apparatus of the present invention;  
         [0028]    [0028]FIG. 2 is a side elevational view of the stock accumulating section, scanning section, and storage section of the bundling apparatus;  
         [0029]    [0029]FIG. 3 is an enlarged view of a portion of FIG. 2;  
         [0030]    [0030]FIG. 4 is an enlarged end elevational view of the bundling apparatus taken from the right end of FIG. 1;  
         [0031]    [0031]FIG. 5 is an enlarged end elevational view of the bundling mechanism of the apparatus;  
         [0032]    [0032]FIG. 6 is a flowchart showing the method for restocking the storage section of the bundling apparatus; and  
         [0033]    [0033]FIG. 7 is a flowchart showing the method for selecting boards of the apparatus. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0034]    Referring now to the drawings, and more particularly to FIG. 1, the selection and bundling apparatus of the present invention is designated generally at  10  and includes an accumulating conveyor  12 , a scanning assembly  14 , a storage rack  16 , a row accumulating section  18 , and a bundling mechanism  20 .  
         [0035]    Referring now to FIGS. 1 and 2, accumulating conveyor  12  includes a support frame  22  formed of a pair of parallel and longitudinally extending side frames  24  and  26 , a forward end  28  and a rearward end  30 . A plurality of powered rollers  32  are arranged parallel to one another and extend transversely between side frames  24  and  26  from forward end  28  to rearward end  30 . Rollers  32  are oriented coplanar and are powered to rotate in the same direction, so as to carry wood stock placed on the forward end towards the rearward end of frame  22 . A plurality of longitudinally extending parallel dividers  34  are spaced above the rollers to form a plurality of longitudinally extending tracks in which wood stock is placed and carried on rollers  32 . Preferably, the rollers  32  of accumulating conveyor  12  are operated at a speed which carries the wood stock at a rate of approximately 60 feet per minute.  
         [0036]    Referring now to FIGS. 1 and 3, each track  36 , formed between pairs of divider walls  34 , has an operable gate  38  movable between a stop position projecting upwardly into the path of wood stock  40  in track  36 , and a lowered position (shown in solid lines in FIG. 3) permitting stock  40  to pass by gate  38  within track  36 . Gate  38  is preferably operated by a pneumatic cylinder  42  or the like, which in turn is connected to a central control  44 . Central control  44  thereby selectively operates gate  38  to permit or stop the passage of stock  40  within each track  36 .  
         [0037]    As shown in FIG. 1, accumulating conveyor  12  includes a plurality of tracks  36 , each of which will hold a plurality of individual pieces of wood stock  40 . Each piece of stock is preferably of uniform width and thickness, but has a variety of unequal, random lengths based upon cuts made to remove defects from the natural raw material. A sensor  46  is located proximal the rearward end  30  of frame  22  in each track  36 , in order to detect the presence of a piece of stock  40  in each of the particular tracks  36 . Sensor  46  is shown schematically above the accumulating conveyor  12 , but could be located below the conveyor between rollers  32 , as well. Sensors  46  may be of any conventional mechanical, ultrasonic, conductive or photoelectric switch, and are all connected to central control  44  to transmit a signal to the central control indicating the presence of a piece of stock  40  within the track and stopped at the gate  38 . When central control  44  determines that a piece of stock  40  in a particular track  36  is ready to continue to the scanning area, it will send a signal to cylinder  42  to drop gate  38 , allowing the stock to move past the gate on the powered rollers  32 .  
         [0038]    Referring now to FIG. 3, scanning assembly  14  includes a horizontal, low friction, wear resistant bed plate  48  extending from the rearward end  30  of accumulating conveyor frame  22  to the forward end of storage rack  16 . Bed plate  48  is positioned at a height coplanar with the tops of rollers  32 , such that wood stock  40  passing past gate  38  will slide across the top surface of bed plate  48  after leaving the rearward most roller  32 .  
         [0039]    A pair of constant speed feed rollers are positioned parallel to one another and slightly spaced apart, oriented transversely to the direction of travel of stock  40 , and spaced above the bed plate  48  a distance such that the feed rollers will engage and feed stock  40  by friction between the feed rollers  50  and bed plate  48 .  
         [0040]    Feed rollers  50  rotate at a speed to feed stock  40  at a rate of about 240-250 feet per minute, much faster than the speed of travel of stock  40  on the accumulating conveyor  12 . Because feed rollers  50  propel the stock  40  at a faster rate than accumulating conveyor  12 , a gap develops between multiple pieces of stock within the same track  36 . The central control  44  will detect this gap via sensor  46 , and trigger cylinder  42  to raise gate  38  to the stop position, to thereby halt the movement of the next piece of stock  40 .  
         [0041]    Scanning assembly  14  includes a sensor  52  for determining the length of each piece of wood stock  40  which passes through the scanning assembly  14 . In the preferred embodiment of the invention, a photoelectric sensor including a transmitter  52   a  and receiver  52   b  (shown in FIG. 1) is arranged horizontal between feed rollers  50  and parallel to feed rollers  50 , at a height above bed plate  48  such that wood stock  40  will break the photoelectric beam as it passes over the top of bed plate  48  as it is fed by feed rollers  50 . Sensor  52  is connected to central control  44 , and the central control will detect the time at which the leading edge of a piece of stock  40  breaks the beam between transmitter  52   a  and receiver  52   b , and the time at which the stock no longer interrupts the lightbeam. Because feed rollers  50  are rotated at a known constant speed, the length of the piece of stock  40  can be determined by the elapsed time that the lightbeam is interrupted. A pair of feed rollers  50  are utilized, a first feed roller upstream of the sensor and a second feed roller downstream of the sensor  52 , such that the wood stock  40  is moved at a constant rate of speed as it passes through the beam of sensor  52 .  
         [0042]    An alternative to the use of a timer would be the use of a sensor on a cog wheel attached to feed rollers  50 . The teeth on the cog wheel are counted by the controller as the feed rollers  50  rotate during the period of time that a board is sensed by the sensor. Other similar and equivalent methods of measuring boards are contemplated by the inventor.  
         [0043]    While a single transmitter  52  is shown in the preferred embodiment of the invention for detecting the length of all of the pieces of wood stock  40  passing through the scanning area, a separate sensor could be utilized with each track  36 , or with a group of tracks  36 , if a faster scanning rate is desired.  
         [0044]    Referring now to FIGS. 1 and 3, feed rollers  50  advance the wood stock  40  through the scanning assembly  14  to storage rack  16 . Storage rack  16  includes a plurality of channels  54  directly aligned with each of tracks  36 , to receive wood stock  40  from each of tracks  36 . As shown in FIG. 4, each of channels  54  is separated by parallel side walls  56  and a bottom gate  58 . Each bottom gate  58  is pivotally mounted along one edge on a hinge  60  to permit a piece of wood stock  40  to be selectively dropped out the bottom of the channel  54  onto a cross-feed conveyor  62 . As shown in FIG. 4, each bottom gate  58  has a pneumatic cylinder  64  connected thereto for pivoting the gate  58  between a generally horizontal storage position, and a sloped “drop” position.  
         [0045]    A plurality of cross-feed conveyors  62  are arranged transversely under storage rack  16 , and are preferably belt conveyors. Conveyors  62  move wood stock  40  dropped from storage rack  16 , transversely to a row accumulator conveyor located in the row accumulating section  18  immediately adjacent the storage rack  16 . Each cylinder  64  is connected to central control  44  such that central control  44  selectively drops the appropriate gates  58  to select particular pieces of wood stock  40  to row accumulating section  18 . As each piece of wood stock  40  reaches the end of cross-feed conveyors  62 , it drops on to the row accumulator conveyor  66 , which transports the wood stock  40  longitudinally to a row accumulator apparatus  68  in row accumulating section  18  (as shown in FIG. 1). Row accumulator apparatus  68  includes a stop gate  70  located at the downstream end of accumulating conveyor  66 , operable between a stop position projecting downwardly into the path of wood stock  40  being carried on conveyor  66 , and an upper position permitting wood stock to travel past the gate to be fed back to the operator at the entry point of the selection and bundling apparatus  10 . A pair of sensors  72  and  74  are positioned over accumulating conveyor  66  and spaced upstream of stop gate  70  predetermined distances. As noted above, a row of wood stock is accumulated to a predetermined length which desirably falls between minimum and maximum target lengths. The minimum target length is detected by sensor  72  and the maximum target length is detected by sensor  74 , positioned upstream of sensor  72 .  
         [0046]    For example, if the minimum and maximum target lengths are seven feet and eight feet respectively, wood stock  40  will be carried by accumulating conveyor  66  to stop gate  70 . Each subsequent piece of wood stock will contact a previous piece to form an accumulated row length. If the selected pieces form a length which does not reach to the location of sensor  72 , the central control  44  will reject the entire row and recirculate the stock back to the operator for placement on the accumulating conveyor  12 . If the row of accumulated wood stock is detected by sensor  72  but not detected by sensor  74 , then the central control  44  will have confirmation that the accumulated length of the wood stock pieces is within the minimum and maximum target lengths, and will proceed with processing. If both sensors  72  and  74  detect a piece of wood stock, then central control  44  will recognize that the accumulated row length is beyond the maximum parameters, will reject the row, and will activate stop gate  70  to recirculate the wood stock back to the operator for placement back in the accumulating conveyor  12 .  
         [0047]    Gate  70  also permits the selection and bundling apparatus to purge the storage rack  16  of stock, such as upon startup or the like.  
         [0048]    Referring now to FIG. 5, if the accumulated row of stock, designated generally at  76  is within the appropriate length parameters, it is pushed transversely from the accumulating conveyor  66  by a pneumatic pusher  78  on to a layer accumulator  80 . The layer accumulator holds a plurality of stock rows  76  until a sufficient number of rows are accumulated for a particular bundle width. FIG. 5 shows a bundle width of three stock rows  76 . Once a sufficient number of rows has accumulated to form a layer, the same pneumatic pusher  78  pushes the entire layer on through the layer accumulator  80  into the bundle accumulator  82 . A plurality of layers are subsequently stacked on the bundle accumulator  82  to a predetermined height for a bundle  84 .  
         [0049]    The layer accumulator  80  is pivotally mounted along a central longitudinal axis so that the last layer to be stacked on bundle  84  may be inverted before placement on top of the bundle. Once bundle  84  has been formed, an out-feed conveyor  86  transports the bundle to the bundle packaging station (not shown).  
         [0050]    Referring once again to FIG. 1, the central controller  44  includes a processor which is programmed to automate the entire selection and bundling apparatus  10 . As each piece of wood stock  40  moves from a track  36  through scanning assembly  14  to storage rack  16 , the controller stores the length of the particular board along with the location of that board in storage rack  16 . Once all, or a predetermined number of channels  54  in storage rack  16  are filled with wood stock, the central controller  44  is programmed to determine the best combination of lengths available to fit the target length of an accumulated stock row  76 .  
         [0051]    The central controller  44  may select as few as one board, or as many as five or six pieces to best fit the target length row. However, the computer program biases the selection process to give preference to longer pieces in making the piece selections for a stock row  76 , rather than having the controller determine the absolute best mathematical solution. This is because the best mathematical solution has a tendency to utilize shorter pieces first, since a row with many short pieces will have more possible combinations and therefore will more easily fit an accurate target length. If this occurs, only long pieces would be left in the storage rack, and a combination of long pieces would not fit the target length.  
         [0052]    In operation, the initial step in operating bundling apparatus  10  is in the supplying of wood stock to accumulating conveyor  12 . This may be accomplished either manually, or by other automated apparatus, to substantially fill conveyor  12  with random lengths of stock  40 .  
         [0053]    Referring now to FIG. 6, the central processor  34  executes an in-feed routine designated generally at  88  in order to fill channels  56  of storage rack  16  (as shown in FIG. 1). This routine includes the step of selecting one row or channel of storage rack  16  and determining whether the particular row is empty, and also detects whether there is any wood stock available on the in-feed accumulating conveyor  12 . If either there is no stock available or the storage rack row is not empty, the routine determines whether the detected row is the last row of storage rack  16 . If not, it repeats the sequence with the next subsequent row of the storage rack.  
         [0054]    If the storage rack row is empty and the in-feed conveyor has stock available, then the in-feed routine will activate a gate  38  to permit a piece of wood stock to be fed and measured in scanning apparatus  14  and stored in the empty channel of storage rack  16 . This process is then repeated for each channel  56  of storage rack  16  until all of the channels have been checked and filled if possible.  
         [0055]    Once storage rack  16  has filled to a predetermined capacity, central controller  44  will initiate the stock row selection routine  90 , shown in detail in FIG. 7. As discussed above, the central controller will first look to determine whether a single board is present in one of channels  56  which has a length greater than 85 inches. If so, the controller will activate the bottom gate  58  of the selected channel  54  to drop the board on the cross-feed conveyor and advance the board to the row accumulating conveyor  66  (as shown in Figure 4).  
         [0056]    Once there is an empty row  54  in storage rack  16 , the central controller will then go back to the in-feed routine  80  to fill that row, assuming that additional wood stock is available on accumulating conveyor  12 .  
         [0057]    If no single board in storage rack  16  has a length greater than 85 inches, the stock row selection routine then determines whether the total length of the available boards is greater than 93 inches. If not, then no combination of boards can be combined to meet the target length range, and either additional boards will be added to storage rack  16 , or the controller  44  will wait for more stock to appear on the in-feed conveyor  12 .  
         [0058]    Assuming that the total length of the available boards is greater than 93 inches, then the stock row selection routine will first identify the longest board available and assume that it is part of the solution. Central controller  44  then determines the best possible fit of remaining boards combined with the longest board, up to a maximum of five total boards. If the best solution does not fall between the minimum and maximum length (in this case 93 inches and 99 inches, respectively) then the routine will eliminate the longest board from consideration and continue the routine using the next longest board. This will repeat until the best solution falls between the minimum and maximum length. Central controller  44  will then open the bottom gates  58  of the selected channels  54  to drop the boards that are part of that solution. The central controller then returns to the in-feed routine to resupply the storage rack  16 , as described above.  
         [0059]    Whereas the invention has been shown and described in connection with the preferred embodiment thereof, many modifications, substitutions and additions may be made which are within the intended broad scope of the appended claims.