Abstract:
A system and apparatus for dispensing lumber is described. The apparatus includes a pusher, such as a chain driven lug, which pushes against the side of a row of lumber, thus sequentially pushing the top row of a lumber pack into a transport system. The apparatus also includes a hydraulic lift which enables the lumber pack to be moved upwards for the dispensing of subsequent rows.

Description:
FIELD 
       [0001]    This application relates to the handling of sawn timber and similar products, and particularly the dispensing of lumber from packs for processing. 
       BACKGROUND 
       [0002]    When processing lumber it is necessary to take long boards of timber and saw them into required lengths. Timber is typically supplied in packs of stacked boards. Packs may be, for instance, in the order of 15 boards wide and 15 boards high 
         [0003]    Traditionally, it has been necessary for workers to move each board in turn to a saw in order for it to be cut to a required length. As will be appreciated, this is a highly labour intensive operation. 
         [0004]    It is therefore desirable to automate the supply of boards to a saw by means of a suitable mechanism. Such automation presents challenges, however. 
         [0005]    Boards are heavy and bulky, and for this reason gravity feed mechanisms are impractical. Instead, the mechanism must be equipped to remove individual boards from the top of a pack. As the height of a pack changes as boards are removed, the mechanism must be able to adapt for this. 
         [0006]    The width of boards is generally constant within a pack, but may vary between packs, and for different applications. Accordingly the mechanism must be equipped to manage a variety of board widths. 
         [0007]    One mechanism known to the applicant which attempts to overcome these problems does so by positioning wood packs beneath an overhead rail onto which is located a vertically extending suction plate. The suction plate is positioned above a board to be retrieved, and then lowered to contact this board. A vacuum is applied to the suction plate in order to hold the board in place. The suction plate is then raised to the rail, and moves along the rail until the board is over a destination conveyor. The suction plate is then lowered until the board is close to the conveyor, at which time the vacuum ceases and the board is allowed to fall into position. 
         [0008]    Another mechanism known to the applicant uses a similar overhead rail concept, with a vertically extending grabbing mechanism which uses two self-tapping screw threads to bore into the board and hold into position. The threads are reversed when the board is ready to be dropped to its destination. This has an advantage over the suction plate in that the connection is much more secure, and the likelihood of a board being dropped whilst being moved is lessened. On the other hand, there is a significant disadvantage in that two holes are bored into the board. 
         [0009]    Both of these mechanisms have further disadvantages. The mechanism must be able to identify a targeted board, and to locate directly above it. This can require highly complex measuring devices such as laser guidance systems. Should boards not be taken in an appropriate sequence, the pack may become unstable and boards may fall over. Finally, the arrangements are sensitive to changes in layout and dimensions, which suggests that scaling of these mechanisms for different sized operations is at best difficult. 
         [0010]    It would be advantageous to provide an alternative lumber handling mechanism which seeks to avoid some of the difficulties associated with known mechanisms. 
       SUMMARY 
       [0011]    According to one implementation, there is provided a lumber dispensing apparatus having: 
         [0012]    a pack-supporting platform which is able to be moved vertically; 
         [0013]    a row-moving pusher which is able to be moved horizontally; 
         [0014]    a rotation-preventing guide located above the pack-supporting platform; and 
         [0015]    a lumber restraint located alongside the pack-supporting platform, whereby 
         [0016]    when the pack-supporting platform contains a pack of timber, comprising boards arranged in rows and having a top-most row: 
         [0017]    the pack-supporting platform is arranged to raise the pack until the top-most row is in position adjacent the row-moving pusher; and 
         [0018]    the row-moving pusher is arranged to engage the top-most row of timber at an end remote from the lumber restraint, and to push the top-most row of timber in a transverse direction over the lumber restraint, the lumber restraint being lower by a vertical displacement less than the depth of two boards than a highest part of the top-most row when the pack is raised. 
         [0019]    It will be appreciated that a member is provided next to the lumber restraint to catch each board as it is dispensed, and to move it into position for further processing. 
         [0020]    In accordance with a second implementation, there is provided a method of dispensing lumber from a pack, the pack comprising boards of timber arranged in rows, the method including the steps of: 
         [0021]    locating the pack beneath a rotation-preventing guide; raising the pack until the topmost row is adjacent the rotation-preventing guide; 
         [0022]    pushing the top-most row in a transverse direction so that boards of the top-most row sequentially fall over a side of the pack; and 
         [0023]    subsequently raising the pack until the new topmost row is adjacent the rotation-preventing guide. 
         [0024]    It is preferred that the lumber dispensing apparatus is associated with a lumber transport system, which may include a series of continuous loop transporters, such as transfer chains. The lumber dispensing apparatus may be equipped to operate in series, whereby a plurality of lumber dispensing apparatuses are arranged in sequence. Each of these apparatuses may include a portion of the lumber transport system located above the rotation-preventing guide. 
         [0025]    Each lumber dispensing apparatus may be associated with a lumber receiver adjacent the lumber restraint, onto which the dispensed lumber is pushed. The lumber transport system may provide an alternative route for lumber to reach the lumber receiver: it may be pushed from the pack onto the receiver, or may be brought from another pack, over the rotation-preventing guide, to the lumber receiver. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    It will be convenient to further describe several implementations of the lumber handling apparatus, including both lumber dispensing apparatus and lumber transport system. Other embodiments are possible, and consequently the particularity of the following description is not to be understood as superseding the generality of the preceding description. In the drawings: 
           [0027]      FIG. 1  is a side view of a lumber dispensing apparatus in accordance with the present invention; 
           [0028]      FIG. 2  is a upward-looking cross section through line A-A of the lumber dispensing apparatus of  FIG. 1 ; 
           [0029]      FIG. 3  is an enlarged view of a lumber restraint within the lumber dispensing apparatus of  FIG. 1 ; 
           [0030]      FIG. 4  is a plan view of the lumber restraint of  FIG. 3 ; 
           [0031]      FIG. 5  is a perspective of a lumber dispenser utilising three of the lumber dispensing apparatuses of  FIG. 1 ; and 
           [0032]      FIG. 6  is a schematic perspective of a lumber handling apparatus including six of the lumber dispensers of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0033]    Referring to the Figures, there can be seen in  FIG. 1  a lumber dispensing apparatus  10 , having an upright  12  and a cantilevered cross bar  14 . 
         [0034]    The cross bar  14  houses a dispensing drive mechanism, in the form of a continuous loop dispensing chain drive. The chain drive is located between a drive shaft  16  and an idler sprocket  18 , located at longitudinally spaced ends of the cross bar  14 . 
         [0035]    The chain drive operates a row-moving pusher in the form of a dispensing lug  20 . The dispensing lug  20  extends vertically downward from a carriage  22 , which is coupled to the chain drive by a mount block  24 . 
         [0036]    Rotation-preventing guides  26  are located on either side of the cross bar  14 . The guides  26  are laterally spaced from the cross bar  14 , and are held into a position vertically beneath the cross bar  14  by brackets  28 . The brackets  28  are pivoted against the cross bar  14 , and are resiliently biased by torsion springs  27  or other resilient members to maintain the guides  26  in a neutral position slightly beneath the height of the lug  20 . 
         [0037]    The guides  26  are elongate, and are parallel to a longitudinal axis of the cross bar  14 . In their neutral position the guides  26  are located below the cross bar  14 . 
         [0038]    The dispensing apparatus  10  also includes a pack supporting platform  30 . The platform  30  is mounted onto a trolley  32 , sized and shaped to locate over a hydraulic lift  34 . The hydraulic lift  34  is located directly beneath the cross bar  14 , and allows the platform  30  to be raised from an initial position wherein wheels  36  of the trolley  32  are in contact with the floor to a final position wherein the platform  30  may be in contact with the guides  26 . 
         [0039]    The dispensing apparatus further includes a second upright  40 . In  FIG. 1 , a second upright  40  can be seen spaced from the first upright  12  on the opposite side to that of the hydraulic lift  34 . This second upright  40 , although coupled to the first upright  12  by an angled connecting beam  42 , is more correctly considered as being associated with an adjacent dispensing apparatus  10  as will be seen below. 
         [0040]    The second upright  40  includes a lumber restraint  44  located at the upper end thereof. The lumber restraint  44  comprises a length of square section tubing  45  extending horizontally, in the horizontal direction perpendicular to the guides  26 . The lumber restraint  44  has a plurality of receiving guides  46  spaced along its length. The receiving guides  46 , which in the embodiment shown are formed from bars welded into position, extend upwardly at an angled of about 35° to the horizontal, from a low point along the front top corner of the square section tubing  45  to a high point above a top face of the square section tubing  45 . The lumber restraint  44  also includes a dispensing guide  48  which is formed from flat bar extending between the high point of the receiving guides  46  to the top rear corner of the square section tubing  45 . The dispensing guide  48  is thus angled at about 55° to the horizontal. 
         [0041]    It will be appreciated that a gap  50  extends between neighbouring receiving guides  46 , and anything entering this gap will be trapped beneath the dispensing guide  48 . 
         [0042]    The lumber restraint  44  is located at a height immediately below that of the lug  20 . 
         [0043]      FIG. 5  shows a lumber dispenser  60 , which is formed by three lug dispensing apparatuses  10  laterally spaced. It will be noted that the three dispensing apparatuses  10  share certain elements: there is a common drive shaft  16  extending through all three cross bars  14 ; there is a single trolley  32  and hydraulic lift  34 ; and a single lumber restraint  44 . 
         [0044]    Use of the lumber dispenser  60  will now be described. 
         [0045]    A pack of lumber  62  is first loaded onto a trolley  32 . As shown in  FIG. 5 , a pack  62  comprises boards  64  stacked so as to have a top row  66 , a second row  68  and subsequent rows  70 . The trolley  32  is then positioned over the hydraulic lift  34  such that the boards  64  are parallel to the lumber restraint  44 . 
         [0046]    The hydraulic lift  34  then raises the platform  30  until the top row  66  is level with the lugs  20 . This has the effect of raising the guides  26 , which are held in contact with the top row  66  by virtue of the torsion springs  27 . 
         [0047]    As can be seen in  FIG. 6 , the lumber restraint  44  connected to an adjacent lumber dispenser  60  is positioned next to the platform  30 , on the other side of the platform  30  to the first uprights  12 . The arrangement is such that the square section tubing  45  of the lumber restraint  44  locates against the second row  68  of the pack  62 , once the top row  66  is raised to the appropriate height. 
         [0048]    Rotation of the drive shaft  16  causes simultaneous movement of the carriages  22  and their associated lugs  20  along the cross bars  14 . The lugs  20  engage with an innermost board  64  of the top row  66 , and push it in a direction away from the first upright  12 . This board  64  engages its neighbouring board  64 , and so on, until the entire top row  66  is being pushed away from the first upright  12 . The boards are held down by the guides  26 , which prevent rotation of any one board. 
         [0049]    The outermost board  64  of the top row  66  is pushed over the lumber restraint  44 , and falls to a lumber receiver which is part of the lumber transport system to be described below. The lumber transport system carries the outermost board  64  away, in time for the next board  64  to be pushed over the lumber restraint  44 . 
         [0050]    Any slats (that is, small pieces of timber used for stabilising purposes) within the pack  62  will fall into the gap  50 . 
         [0051]    When the entire top row  66  has been pushed over the lumber restraint  44 , the direction of drive shaft rotation is reversed and the lugs  20  return to their initial position. The hydraulic lift  34  then raises the platform until the previous second row  68 , now a new top row  66 , is in position for dispensing. 
         [0052]    The lumber handling apparatus has a plurality of lumber dispensers  60 , together with the lumber transport system. 
         [0053]    The lumber transport system centres around a number of continuous loop transporters, being continuous chains having lumber engaging lugs located regularly along their length. 
         [0054]    A first such transport chain  80  is located along the connecting beam  42 . A lumber guide  82 , being simply a short length of steel, leads from the lumber restraint  44  to the base of the connecting beam  42 . This constitutes the lumber receiver. The first transport chain  80  is then arranged to transport a board  64  from the lumber receiver to the top of the cross bar  14 . A second transport chain  84  then moves the board  64  along the cross bar  14  to a drop ramp  86  located at a distal end of the cross bar  14 . The board  64  slides down the drop ramp  86  to land on a first transport chain  80  of the next lumber dispenser  60 . 
         [0055]    In this way the lumber handling apparatus becomes entirely modular.  FIG. 4  shows six lumber dispensers  60  arranged to supply boards  64  to a jump conveyor  90  and thence to a saw  92 . Any one lumber dispenser drive shaft  16  can be operated in order to push a single board into the transport system, and then to the jump conveyor  90 . Appropriate timing of the drive shafts  16  means that timber from desired packs  62  can be provided to the jump conveyor  90  at a required rate. When a pack  62  is exhausted, its trolley  32  can be lowered, removed, restocked, and returned without disturbing the operation of the transport chains, and therefore without interrupting continuous supply of timber to the saw  92 . 
         [0056]    Modifications and variations as would be apparent to a skilled artisan are deemed to be within the scope of the present invention.