Abstract:
A log-feeding device comprises two relatively movable units each carrying automatically self-centering chain-engaging sprockets, the chains being formed of flights provided with channels having serrations and knife-edges for grasping the bark surface of a log being fed therethrough.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Benefit of U.S. Provisional Application for Patent Ser. No. 61/202,436 filed on Feb. 27, 2009, which is incorporated herein by reference, is hereby claimed. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a log-feeding device for a bark-stripping machine. 
       BACKGROUND OF THE INVENTION 
       [0003]    Many types of such devices have been proposed and operate with varying degrees of efficiency and efficacy. Most of these devices employ at least one array of rollers, which capture and centre logs for their passage to and through the debarking machine. Some examples of the prior art devices are listed as follows: Canadian Patent No. 601,739 to Nicholson; U.S. Pat. No. 3,374,839 to Foster et al; U.S. Pat. No. 3,724,518 to Zehavi et al; U.S. Pat. No. 3,833,162 to Sato; U.S. Pat. No. 4,609,019 to Hutson; and U.S. Pat. No. 6,216,756 to Mason. All of the foregoing propose the use of rollers arranged in differing configurations and mounted on support arms allowing the accommodation of surface contours and a range of log diameters. However, maintenance of devices of this kind can be difficult and required at frequent intervals thus occasioning high operational costs, bearing in mind the loss of production time expended on this activity. 
         [0004]    Accordingly, there is a need for an improved log-feeding device, and components thereof, which is relatively simple in design and operation and offers a lower maintenance cost burden by reducing downtime. 
       SUMMARY OF THE INVENTION 
       [0005]    It is therefore a general object of the present invention to provide an improved log-feeding device, and components thereof, for a bark-stripping machine. 
         [0006]    An object of the present invention is to provide a compact log-feeding device with ease of access to its moving parts, thus facilitating maintenance and thereby reducing down time. 
         [0007]    Another specific object of the present invention is to provide a powered floating roller assembly for engagement in use with a log to feed same through the device and thence to a debarking machine, the assembly being of relatively simple construction with a self-compensating centering mechanism for ensuring a smooth passage of the log into and through the device and then into the log debarking machine. 
         [0008]    A yet further object of the present invention is to provide a feed chain incorporating a plurality of contact members for frictionally engaging and capturing a log for centering and feeding it towards and into the debarking machine, the contact members having a novel and unique operational profile that is functionally effective, and which can accommodate a wide diameter variety of logs, starting with relatively small diameter logs. 
         [0009]    According to an aspect of the present invention, there is provided a log feeding  20 , device comprising a base mountable on a substructure, two complementary log feeding units connected to one another and mounted on the base, a first log feeding unit including a housing provided with a first drive plate having a first sprocket array comprising a first pair of drive sprockets disposed one above the other and being mounted on first substantially horizontal drive shafts extending through the first drive plate, the axes of the said drive shafts being biased toward one another and movable in relation to the drive plate in an arcuate manner in a substantially vertical plane, a pair of upper and lower idler sprockets disposed one above the other and provided on the housing of the first log feeding unit spaced from the first pair of drive sprockets, first biasing mechanisms associated with said drive shafts for effecting such biasing movement, a second log feeding unit including a housing provided with a second drive plate having a second sprocket array comprising an upper sprocket and a lower sprocket each mounted on a second substantially horizontal drive shaft extending through the second drive plate, the second shafts being movable in relation to the second drive plate in substantially vertical and horizontal planes, actuating and biasing mechanisms associated with said second drive shafts for effecting such relative movement and in use biasing the sprockets of the second log feeding unit toward one another, an upper feeder chain reeved around the upper sprockets of the first feeding and the second feeding units, a lower feeder chain reeved around the lower sprockets of the first feeding unit and the second feeding unit, the upper and lower feeder chains being provided with log-engaging flights together forming a pathway through which in use a log is transported therealong by means of the feeder chain engagement therewith, and a drive arrangement for the sprockets. 
         [0010]    In use the base of the log feeding device would be placed upon the substructure, for example the ground or a floor of a wood mill or wherever as appropriate. 
         [0011]    The housing of the first log-feeding unit includes a top part on which the drive arrangement for the sprockets is conveniently provided, the drive arrangement consisting of an electric or other motor coupled to a gearbox the axle of which carries a drive pulley over which a drive belt passes and engages pulleys provided on the drive shafts on one side of the first drive plate. The drive belt serves to drive all the sprockets on the first log-feeding unit, the sprockets being disposed on the other side of the first drive plate. 
         [0012]    The first log-feeding housing further comprises the first drive plate attached to and depending from the top part, and two sides. The first drive plate is formed with two arcuate slots through which the first drive shafts extend orthogonal thereto. 
         [0013]    The housing of the second log-feeding unit includes a top part with the second drive plate attached thereto and depending vertically therefrom with the second drive shafts extending therethrough and carrying the second sprocket array on the side of the plate facing the first log-feeding unit. The second drive plate is also formed with clearance slots through which the drive shafts extend and within which they are capable of moving. 
         [0014]    The base is slidably mounted on the substructure for displacement of the device thereon using an actuation mechanism for effecting such displacement. The actuation mechanism is typically constituted by at least one fluid actuable ram acting between the base and the substructure. 
         [0015]    Accordingly once the sprockets of the two housings are aligned together a path for a log is thus defined. In this respect upper and lower feed chains are provided in endless loops and are reeved around three upper and three lower sprockets of the two housing. Tensioning of the chain to the appropriate level is achieved by activating the second actuating mechanisms acting on the second drive shafts in a horizontal direction. 
         [0016]    Each chain comprises a series of links engageable with the sprockets, the links carrying the log-engaging flights each of channel form with serrations in combination with knife-edges. The channels on each chain at the nip between the two chains form the pathway for the log. It will be understood that the flights on one chain are offset from those on the adjacent chain to avoid interference one with the other during travel. 
         [0017]    Suitably placed proximity sensors may be disposed in association with the log-feeding device whereby an approaching log carried on a feed conveyor to the device is sensed and the primary sprockets carried on the second log-feeding unit are actuated to provide an appropriately sized opening to allow feeding of the log into the pathway formed by the two chains. Thereafter the sprockets are biased towards the pathway formed for the passage of the log. In similar manner, the biasing mechanisms provided for the drive sprockets and the idler sprockets of the first log-feeding unit are biased toward such pathway. The biasing mechanisms may conveniently be an open compression spring or may be sealed gas-filled units allowing compression and expansion. 
         [0018]    According to another aspect of the present invention, there is provided a log-engaging member device for mounting on a feeder chain for contacting and carrying logs, the log-engaging member device comprises a body formed of a channel section having serrations and knife-edges, the knife-edges being V-shaped and the channel section tapering towards a centre of the member body. The serrations and the knife-edges are substantially perpendicularly oriented relative to one another. 
         [0019]    Other objects and advantages of the present invention will become apparent from a careful reading of the detailed description provided herein, with appropriate reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    Further aspects and advantages of the present invention will become better understood with reference to the description in association with the following Figures, in which similar references used in different Figures denote similar components, wherein: 
           [0021]      FIG. 1  is a perspective view of the device taken from the discharge end thereof, and without the feed chains for clarity purposes; 
           [0022]      FIG. 2  is a top plan view of the device shown in  FIG. 1 ; 
           [0023]      FIG. 3  is an elevation view in the direction of the arrow A in  FIG. 1 ; 
           [0024]      FIG. 3   a  is a front elevation view in the direction of the arrow C in  FIG. 1 ; 
           [0025]      FIG. 4  is an elevation view in the direction of the arrow B in  FIG. 1 ; 
           [0026]      FIG. 5  is an internal elevation view of the first log-feeding housing showing the biasing mechanisms and the interlocking mechanisms for the sprocket drive shafts; 
           [0027]      FIG. 6  is an internal elevation view of the second log-feeding housing showing the biasing and actuating mechanisms and the interlocking mechanisms for the sprocket drive shafts; 
           [0028]      FIG. 7  is a side view of the upper and lower feed chains; 
           [0029]      FIG. 8  is a view on the line  8 - 8  of  FIG. 7  with a log of relatively large diameter held between the feed chains; 
           [0030]      FIG. 9  is a similar view to that shown in  FIG. 8  with a log of relatively small diameter held between the feed chains; 
           [0031]      FIG. 10  is a perspective view of a flight forming part of the feed chains; 
           [0032]      FIG. 10   a  is an underside perspective view of the flight of  FIG. 10 ; 
           [0033]      FIG. 10   b  is an end elevation view of the flight of  FIG. 10   a  showing the positioning of a log as it is primarily engaged by the flight; and 
           [0034]      FIG. 11  is a diagrammatic side view of the log-feeding device in use with logs being primarily captured by and fed through the device between the upper and lower feed chains. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0035]    With reference to the annexed drawings the preferred embodiment of the present invention will be herein described for indicative purpose and by no means as of limitation. 
         [0036]    Referring first to  FIGS. 1 to 6 , there is illustrated a log-feeding device  1  for a debarking machine (not shown) comprising a base  2  slidably mounted on a rigid structure formed of spaced apart ground-engaging guide runners  4 , and on which is mounted a first log-feeding unit  6  interconnected with a second log-feeding unit  8  via top and bottom square-sectioned beams  12 , relative movement between the units  6 ,  8  and the base  2  being achieved by a fluid operable ram  10  for each of the runners  4 , with each ram  10  being connected to the respective runner  4  and the first log-feeding unit  6  of the device  1 . The displacement of the device  1  on the runners  4  provides an easy access to surrounding equipment (not shown) of the debarking machine for maintenance purposes. 
         [0037]    The unit  6  is comprised of a housing  14  having a top plate  16  on which is mounted a drive arrangement  17  consisting of a drive motor  18  driving, via drive belt  19  or the like-(shown in dotted lines in the Figures), a gearbox  20  provided with an output shaft  22  for driving a transmission belt  24 . A vertical drive plate  26  provides a base on which movable cantilever arms  28  for upper and lower drive shafts  30  carrying drive sprockets  32  are mounted. The shafts  30  protrude through the drive plate  26  which has arcuate slots  34  provided therein whereby movement of the cantilever arms  28  about respective pivot shaft  27  occasions arcuate movement of the shafts  30  and thus of the sprockets  32 . As can be more readily seen in  FIG. 4  to the rear of the plate  26  there is arranged a drive set  40  for the transmission belt  24  including three drive cogs  42  mounted on stub shafts  44  in pillow block bearings  46 . Secondary belts  50  are provided for driving the drive shafts  30  as seen in the left hand side of  FIG. 4 . As will be seen the drive belts  24  and  50  are pocketed and engage the teeth of the drive cogs  42  to give positive drive engagement. Idler sprockets  32 ′ are provided in an upper and a lower disposition relative to one another and in line generally with the upper and lower drive sprockets  32  respectively, to rotate about respective pivot shafts  27 ′ via cantilever arms  28 ′, with the shafts  30 ′ protruding through arcuate slots  34 ′ of the drive plate  26 . 
         [0038]    Referring now to  FIG. 5  an internal view of the unit  6  is shown and accommodated between the drive plate  26  and another front plate  61  of the unit are biasing mechanisms  62 ,  62 ′ such as open compression springs or sealed gas-filled units for biasing swinging movement of the cantilever arms  28 ,  28 ′ to bias the respective sprockets  32 ,  32 ′ towards one another, and the respective cantilever arms  28 ,  28 ′ toward corresponding stopper  31 ,  31 ′ preferably made out of flexible material such as rubber or the like. The cantilever arms  28 ,  28 ′ are mechanically interlinked for simultaneous opposite displacements via crossbar  29  pivotally connected thereto, whereby clockwise displacement of one arm  28  causes counter-clockwise displacement of the other arm  28 , thereby ensuring centering of the log being fed there between. 
         [0039]    Referring now to  FIG. 6 , the unit  8  is constituted in part by a housing  70  having a front plate  75  encasing lever arms  72  carrying at their distal ends the drive shafts  74  for sprockets  76 . The drive shafts  74  extend through a second drive plate  75  which is provided with suitable clearance slots  75 ′ allowing vertical and horizontal movement of the shafts. The lever arms  72  are pivotally connected to respective cranks  78  which are interconnected by crossbar  73  pivotally connected thereto. The crossbar  73  (for simultaneous opposite displacement) and the cranks  78 , pivotally mounted on the housing  70  about pivot shafts  77 , are respectively provided with actuating mechanisms  79 ,  79 ′ which latter are fluidly intercommunicating such that added pressure on one  79  occasions a reduction of pressure on the other  79 ′, thus yielding a balancing and centering effect during use. However, the sprockets  76  represent the entry sprockets which are adapted for opening initially to allow entry into the feeder by a log and are then brought together in support mode. In response to a signal from sensor  99  (see  FIG. 3 ) detecting a specific log diameter reaching the device (controller not shown), the actuating mechanisms  79 , typically a sealed gas-filled unit or the like, is inflated, while the other two actuating mechanisms  79 ′, also typically a sealed gas-filled units or the like, are simultaneously retracted to supply gas into the unit  79  to move the two sprockets  76  away from each other and enable the coming log  100  to get into the device  1  there between. Biasing mechanisms  79 ″ are provided also for keeping a tension in the feed chain and further aid in resetting the sprockets  76  once the opening mode has been completed. 
         [0040]    As can be seen from  FIG. 7  upper and lower feeder chains  80  are reeved over the sprockets  32  and  76 ; the mid-sprockets  32 ′ (as best seen in  FIGS. 3 and 5 ) are idler sprockets used to keep tension into the respective feed chain  80  whilst the sprockets  76  are driven by the end driving sprockets  32  powered by the motor  18 . A nip  81  is formed by the chains  80  between the log-engaging member or flights  82  thereof as can more clearly be seen from  FIGS. 3   a ,  8  and  9 . 
         [0041]    Referring now to  FIGS. 10 ,  10   a , and  10   b , detailed views of the flights  82  are to be seen. In particular, each flight  82  is bolted to a base plate  83  (see  FIGS. 8 ,  9  and  11 ) carried by at least one link of the chain  80 . The flight  82  comprises a plate  84  to which is welded a shallow V-shaped channel  85  (see  FIG. 10   b ) narrower at its mid point than at its side (see  FIGS. 10 and 10   a ). The channel  85  is bounded at its edge distal from the plate  84  by an upstanding sharpened blade  86  or knife-edge forming the inside of the V-shape and used to ensure gripping of the flight  82  into the log  100  to lift and prevent the latter from sliding back off the flight  82  as shown in the bottom section of  FIG. 11 . Along the distal edge of the channel  85  there are formed sharp serrations  87  for indenting in use a log to feed same along the device  1  by virtue of the movement of the chains  80 . 
         [0042]    Reference will now be made to  FIG. 11 , which shows diagrammatically the path of a log into the log-feeding device of the present invention, the motor of the feeder having been started, and the chains  80  now moving in the direction of travel shown in the figure, namely to the right as viewed in the drawing. As a log  100  reaches the entry to the feeder by virtue of it being transported by a conveyor shown in outline at  101  in  FIG. 2 , it is captured by a flight  82  on the lower chain  80  and more particularly is first snagged by the blade  86  which cuts into the surface of the log. As other flights come into contact with the log they also grab and capture the log and transport it along the pathway defined between the two chains and their flights. The serrations  87  of the flights  82  assist by their frictional engagement with the surface, i.e. the bark, of the log to feed the log to a debarking machine (not shown).  FIGS. 8 and 9  show the cross sectional view of logs of greater and lesser diameter respectively captured within the flights  82 .  FIG. 10   b  demonstrates the effectiveness of the channel  85  in centering the log should it be initially offset relative to the centre of the pathway. The log  100  merely rolls or slides along the blade  86  into the centre from  100 ′ to  100 ″ for a smooth and efficient passage through the feeder. 
         [0043]    Furthermore, the profile and construction of the chain flights enables the feeder to cater for wide range of log diameters. 
         [0044]    Although the present invention has been described with a certain degree of particularity, it is to be understood that the disclosure has been made by way of example only and that the present invention is not limited to the features of the embodiments described and illustrated herein, but includes all variations and modifications within the scope and spirit of the invention as hereinafter claimed.