Abstract:
The log positioning and conveying apparatus is used for conveying a log from an upstream end to a downstream end, and for positioning a log according to a predetermined downstream position. The apparatus comprises an open frame and a number of powered conveying rollers arranged therein in a row. These rollers, in addition to being rotatable, are displaceable in two directions relative to the open frame, namely, in a vertical direction for correcting the position of the log vertically relative to the open frame, and in a horizontal direction transversal to the longitudinal axis of the conveying apparatus, for correcting the position of the log transversely relative to the longitudinal axis.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to log conveyors for feeding logs to a chip-and-saw apparatus, and more particularly to a log positioning conveyor capable of adjusting the position of the log.  
         BACKGROUND OF THE INVENTION  
         [0002]    For environmental and economical reasons, it is essential to maximize the production of lumber from each log. To achieve the best possible wood yield from a log, the log has to be suitably positioned in relation to the stationary sawing members of a sawing apparatus in which the log is fed, both with respect to the angular position of the log about its longitudinal axis and the orientation and position of the longitudinal axis of the log.  
           [0003]    Modern log-positioning machines are computer-assisted. It is known to scan the front face of the log with an optical scanner, and to subsequently analyze the log image by means of a computer program. The computer can command a log turning apparatus to adjust the angular position of the log about its longitudinal axis, according to a computed optimal log position.  
           [0004]    However, some problems exist in the existing systems. Firstly, the entire geometry of the log is not computed, and consequently, the log-scan of the front face of the log is not necessarily representative of the entire length of the often longitudinally irregular log. Thus, even if the log is rotated to obtain an optimized log position according to the front face of the log, the overall yield from the log may not be optimal. Also, although a certain optimal log position is computed and the log turning apparatus is controlled to rotate the log according to the desired position, the effective real position of the log may not be exactly as desired, since the log may react in an unforeseen manner while it is rotated, and it may accidentally be positioned differently from the computed optimal position.  
         SUMMARY OF THE INVENTION  
         [0005]    The invention relates to a log positioning and conveying apparatus defining an upstream end and a downstream end, and a longitudinal axis extending between said upstream and downstream ends, for positioning a log defining a peripheral surface according to a predetermined downstream position, said log positioning and conveying apparatus comprising:  
           [0006]    an open frame;  
           [0007]    at least two rollers rotatably carried by said frame and defining respective rotational axes arranged transversally to and in a spaced-apart fashion along said longitudinal axis of said log positioning and conveying apparatus;  
           [0008]    first selectively powered roller actuators carried by said frame and allowing said rollers to be selectively independently displaced in a first direction transversal to said longitudinal axis;  
           [0009]    second selectively powered roller actuators carried by said frame and allowing said rollers to be selectively independently displaced in a second direction transversal to said longitudinal axis and transversal to said first direction; and  
           [0010]    third selectively powered roller actuators carried by said frame and capable of selectively rotating said rollers about their respective rotational axes;  
           [0011]    wherein each said roller can be controlled by a corresponding one of said third roller actuators to be rotated for conveying a log along said longitudinal axis towards said downstream end, and by corresponding ones of said first and second actuators to be displaced along said first and second directions respectively for engaging the peripheral surface of the log and gradually correcting the position of the log for positioning the log according to its predetermined downstream position as it is being conveyed towards said downstream end, whereby a dynamic log channel is defined on a load-bearing surface of said rollers for supporting the log in said log channel.  
           [0012]    In one embodiment, said rotational axes of said rollers are parallel and horizontal.  
           [0013]    In one embodiment, said log positioning and conveying apparatus further comprises at least two additional rollers carried by said frame and each spacedly overlying a corresponding one of the first-named rollers and forming longitudinally successive pairs of vertically spaced-apart co-operating rollers therewith, wherein each roller of said pairs of co-operating rollers is controlled by a corresponding one of said third roller actuators to be rotated for conveying a log along said longitudinal axis towards said downstream end, and by corresponding ones of said first and second actuators to be displaced along said first and second directions respectively for engaging the peripheral surface of the log and correcting the position of the log for positioning the log according to its predetermined downstream position as it is being conveyed towards said downstream end, whereby a dynamic log channel is defined between two rollers forming each said pair of co-operating rollers for receiving the log in said log channel, with the two rollers forming each said pair of rollers being destined to engage opposite sides of the peripheral surface of the log as it engages said log channel.  
           [0014]    In one embodiment, said open frame further comprises a number of roller units moveably mounted thereon, each said pair of co-operating rollers being carried by a corresponding roller unit; wherein each said second actuator is operatively connected to a corresponding one of said roller units; and wherein upon selective activation of said second actuators, said roller units will be independently displaced along said second direction, with said rollers being displaced in said second direction along with said corresponding roller unit.  
           [0015]    In one embodiment, said open frame is provided with a number of rail members thereon arranged parallel to each other and parallel to said second direction, and wherein said roller units are provided with track members that engage corresponding rail members, whereby said roller units can be slideably displaced along said second direction.  
           [0016]    In one embodiment, said rollers define an outer peripheral wall and are provided with spikes radially projecting from said outer peripheral wall.  
           [0017]    In one embodiment, said roller units each pivotally carry a pair of pivotable arms each controlled in its pivotal displacement by a corresponding one of said first roller actuators, each said arm of said pair of pivotable arms rotatably carrying a roller.  
           [0018]    The present invention also relates to a log processing system comprising:  
           [0019]    a) a log positioning and conveying apparatus defining an upstream end and a downstream end, and a longitudinal axis extending between said upstream and downstream ends, for positioning a log defining a peripheral surface according to a predetermined downstream position, said log positioning and conveying apparatus comprising:  
           [0020]    an open frame;  
           [0021]    at least two rollers rotatably carried by said frame and defining respective rotational axes arranged transversally to and in a spaced-apart fashion along said longitudinal axis of said log positioning and conveying apparatus;  
           [0022]    first selectively powered roller actuators carried by said frame and allowing said rollers to be selectively independently displaced in a first direction transversal to said longitudinal axis;  
           [0023]    second selectively powered roller actuators carried by said frame and allowing said rollers to be selectively independently displaced in a second direction transversal to said longitudinal axis and transversal to said first direction; and  
           [0024]    third selectively powered roller actuators carried by said frame and capable of selectively rotating said rollers about their respective rotational axes;  
           [0025]    wherein each said roller can be controlled by a corresponding one of said third roller actuators to be rotated for conveying a log along said longitudinal axis towards said downstream end, and by corresponding ones of said first and second actuators to be displaced along said first and second directions respectively for engaging the peripheral surface of the log and gradually correcting the position of the log for positioning the log according to its predetermined downstream position as it is being conveyed towards said downstream end, whereby a dynamic log channel is defined on a load-bearing surface of said rollers for supporting the log in said log channel, said log processing system further comprising:  
           [0026]    b) a control center destined to possess data representing the shape of the log being conveyed through said log positioning and conveying apparatus and to compute an optimal log position for sawing a log according to an optimal wood yield, with said predetermined downstream position corresponding to said optimal log position, said first and second actuators being controlled by said control center; and  
           [0027]    c) at least one log position monitoring scanner each capable of scanning a plane intersecting said log channel upstream of a corresponding one of said rollers, each said at least one monitoring scanner being operatively connected to said control center for forwarding real-time log position data concerning the position of a log;  
           [0028]    wherein said control center will control said first and second actuators to move said rollers along said first and second directions respectively for engaging the peripheral surface of the log and for correcting a deficient position of a log being conveyed by said log positioning and conveying apparatus according to said data representing the shape of the log and to said real-time log position data received from said at least one monitoring scanner.  
           [0029]    In one embodiment, said log processing system further comprises a log-shape scanner linked to said control center and destined to scan a log for forwarding to said control center said data representing the shape of the log being conveyed through said log positioning and conveying apparatus.  
           [0030]    In one embodiment, said log processing system further comprises a log turner linked to said control center, for rotating a log about its log longitudinal axis.  
           [0031]    In one embodiment, said monitoring scanners are infrared optical detectors. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0032]    In the annexed drawings:  
         [0033]    [0033]FIG. 1 is a side elevation of a log-processing system comprising the end portion of a log conveyor, a log-shape scanner, a log turner, a log positioning and conveying apparatus according to the present invention, and a sawing apparatus, with a log being carried by the conveyor being partly shown;  
         [0034]    [0034]FIG. 2 is an enlarged perspective view of the log positioning and conveying apparatus of the system of FIG. 1 with the viewing angle being inverted relative to FIG. 1, i.e. that the downstream end of the apparatus is located on the left-hand side in FIG. 2, part of the frame in the foreground and the base of the apparatus being removed for clarity of the view, FIG. 2 further showing a log being conveyed in the apparatus;  
         [0035]    [0035]FIG. 3 is similar to FIG. 2, but is shown from an inverted angle relative to FIG. 2, i.e. with the downstream end located on the right-hand side in FIG. 3, with part of the frame in the foreground of FIG. 3 being removed for clarity of the view;  
         [0036]    [0036]FIG. 4 is an enlarged side elevation of a roller unit of the log positioning and conveying apparatus of FIGS. 2 and 3;  
         [0037]    [0037]FIG. 5 is a perspective view of the roller unit of FIG. 4;  
         [0038]    [0038]FIG. 6 is a cross-sectional view of the roller unit taken along lines VI-VI of FIG. 5;  
         [0039]    [0039]FIG. 7 is a side elevation of the roller units, the benches on which they are mounted and the optical scanners of the log positioning and conveying apparatus of FIG. 1, with a log being conveyed by the apparatus; and  
         [0040]    [0040]FIG. 8 is a block-diagram suggesting the interaction between different components of the log-processing system of FIG. 1.  
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0041]    With reference to FIG. 1, there is shown a log processing system  1  comprising a log conveyor  122  of known construction with a log-shape scanner  120  mounted thereon, a log turning apparatus  124  of known construction, a log positioning and conveying apparatus  10  according to the present invention, and a sawing apparatus  126  of known construction. Log-processing system  1  is used for conveying a log L from an upstream end  1   a  defined immediately upstream of log-shape scanner  120 , to a downstream end  1   b  defined immediately downstream of sawing apparatus  126 , the log being properly positioned and cut while it is being conveyed by system  1 , as described hereinafter.  
         [0042]    As shown in appended FIGS. 1-7, log conveying and sawing apparatus  10  comprises an open frame  12 , rollers  50 ,  51 , lateral actuators  40 , arm-pivoting actuators  44 ,  45 , roller rotation-inducing motors  55 ,  56 , and log-position monitoring devices  60   a ,  60   b . Apparatus  10  further defines an upstream end  10   a  and a downstream end  10   b , and a longitudinal axis  11  extending from upstream end  10   a  to downstream end  10   b.    
         [0043]    [0043]FIG. 1-3 show log conveying and sawing apparatus  10 . However, in FIG. 2, the orientation of apparatus  10  is inverted relative to the angle of FIGS. 1 and 3, i.e. downstream end  10   b  is on the left-hand side in FIG. 2 while it is on the right-hand side in FIGS. 1 and 3.  
         [0044]    [0044]FIGS. 1-3 show that frame  12  comprises a ground-resting base  16 , four pairs of spaced-apart upright beams  14   b  upstanding from and integrally fixed to base  16 , a pair of longitudinal top struts  14   a  each integrally linking the top ends of the four beams  14   b  of a same side, four top crossbars  15  integrally linking top struts  14   a , and lateral reinforcement bars  14   c  linking each two successive beams  14   b . A protective side panel  20  is mounted to each beam  14   b  downstream thereof. A longitudinal log channel extends between the two sets of four aligned beams  14   b  and between top crossbars  15  and base  16 , as further detailed hereinafter.  
         [0045]    Base  16  supports four roller units mounting benches  22  that are serially longitudinally fixed to base  16  with respective fixing brackets  21 ,  23  that are bolted to base  16 . Each bench  22  integrally carries a pair of spaced-apart rail members  18   a ,  18   b . Each bench  22  forms a rectangular frame defining a central bench opening therein. Each bench  22  is also provided with an actuator bracket  19  carrying a lateral actuator  40  used for selectively shifting roller units  30  laterally, as described hereinafter.  
         [0046]    Four laterally shiftable roller units  30 , as introduced hereinabove, are mounted onto corresponding roller-unit mounting benches  22 . FIGS. 4-6 show that each roller unit  30  comprises a table  34 , two upright plates  32   a ,  32   b  integrally attached to table  34  and a top crossbar  33  extending between and attached to the top end portion of plates  32   a ,  32   b . An opening  38  is provided in the central region of table  34  and a lip  39  contouring opening  38  projects upwardly from the top surface of table  34 . A U-shaped casing  41  projects downwardly from the bottom surface of table  34  into the above-mentioned central bench opening, with its two side arms being fixedly attached to lip  39  and with its open top registering with opening  38 .  
         [0047]    On the bottom surface of table  34 , two longitudinally spaced-apart pairs of transversely aligned rail-engaging track members  31   a ,  31   b  are provided in order for each roller unit  30  to be guided in its slideable engagement on rail members  18   a ,  18   b.    
         [0048]    Roller unit  30  further comprises a protruding finger member  35  fixedly and firmly attached to the side of table  34  adjacent plate  32   b . Finger member  35  links roller unit  30  to its corresponding lateral actuator  40 .  
         [0049]    Lateral actuators  40  are hydraulic cylinders, each firmly affixed to a corresponding bracket  19  and with its piston free end being attached to the finger member  35  of a corresponding roller unit  30 . Roller units  30  being slideably mounted onto a corresponding bench  22 , upon selective activation of actuators  40 , each roller unit  30  can be independently shifted transversally relative to longitudinal axis  11 .  
         [0050]    Each roller unit  30  further comprises a pair of vertically spaced-apart, H-shaped pivot arms  42 ,  43  defining respective transversally spaced-apart side plates  42   a ,  42   b  and  43   a ,  43   b  integrally linked by crossbars  42   c  and  43   c  at an intermediate portion of side plates  42   a ,  42   b  and  43   a ,  43   b . Side plates  42   a ,  43   a  and  42   b ,  43   b  are attached at a first pivot end thereof to the roller unit upright plates  32   a  and  32   b , respectively. Thus, arms  42  and  43  can pivot about respective pivotal axes  36 ′ and  37 ′. Side plates  42   a ,  42   b  and  43   a ,  43   b  further define roller free ends opposite their pivot ends.  
         [0051]    Roller unit  30  is further provided with arm-pivoting actuators  44  and  45 . Actuator  44  is a hydraulic cylinder pivotally attached at one end to the outer surface of side plate  42   a  of arm  42 , and is pivotally attached at its other end to upright plate  32   a  of roller unit  30 . When activated, actuator  44  can hence pivot arm  42  about pivotal axis  36 ′. Actuator  45  comprises two back-to-back hydraulic cylinders  45 - 1  and  45 - 2 . Actuator  45  extends through opening  38  in table  34 , and is pivotally attached at one end to crossbar  43   c  of arm  43  and the other end to a pivotal joint  73  provided within casing  41 . When activated, actuator  45  can hence pivot arm  43  about pivotal axis  37 ′.  
         [0052]    Arms  42 ,  43  carry rollers  50 ,  51  that are journalled at the above-mentioned roller ends of side plates  42   a ,  42   b  and  43   a ,  43   b  respectively. Rotation actuators in the form of rotation-inducing motors  55  and  56  are carried by arms  42  and  43 , respectively, and control the rotation of rollers  50  and  51 .  
         [0053]    A dynamic log channel is defined within apparatus  10 , extending between each pair of vertically spaced rollers  50 ,  51  of all four consecutive roller units  30 . This log channel is said to be dynamic since, upon selective activation of actuators  40 ,  44  and  45 , each roller  50 ,  51  will be displaced vertically and transversely, and the log channel position will thus vary over time.  
         [0054]    Rollers  50 ,  51  are provided with spikes radially projecting from their outer peripheral wall.  
         [0055]    As shown in FIGS. 2, 3 and  7 , apparatus  10  is provided with four pairs of co-operating log-position monitoring scanners  60   a ,  60   b . In one embodiment, scanners  60   a ,  60   b  are infrared optical scanners. Each top monitoring scanner  60   a  is provided on a distinct top beam  15  of frame  12 . Four bottom monitoring scanners  60   b  are attached to base  16 , although they may also simply rest on the ground or on another structure underlying benches  22 .  
         [0056]    Monitoring scanners  60   a ,  60   b  function by pairs, and each scanner of a same pair is arranged in facing alignment with the other scanner of that pair. Top scanners  60   a  are oriented downwardly, and bottom scanners  60   b  are oriented upwardly. Each pair of log-monitoring scanner  60   a ,  60   b  is located upstream of a corresponding roller unit  30 . In one embodiment, top scanner  60   a  is an infrared wave emitter and bottom scanner  60   b  is an infrared wave receiver.  
         [0057]    As schematically shown in FIG. 8, apparatus  10  cooperates with a control center  110 . Control center  110  comprises a computer  100  and an actuator controller  102  communicatively linked together. Actuator controller is linked to actuators  40 ,  44 ,  45 ,  55  and  56  and can selectively control the activation thereof. Computer  100  is operatively connected to log-shape scanner  120  and to log-position monitoring scanners  60   a ,  60   b  and can receive information therefrom.  
         [0058]    In use, a log L is conveyed by conveyor C towards log processing system  1 . While being conveyed onto conveyor  122 , log L will pass through log-shape scanner  120 . Log-shape scanner  120  is of known construction, and will obtain data representative of the three-dimensional shape of log L and transmit this log-shape data to computer  100  of control center  110 . This log-shape data can be for example an assembly of multiple successive equally spaced two-dimensional image scans from which the entire log shape is more or less precisely determined. A three-dimensional virtual model of the log can then be created by computer  100 , which is representative of the real shape of the log. From this three-dimensional model, an optimal wood yield can be computed by computer  100  according to known yield computing methods.  
         [0059]    As log L is conveyed beyond the free extremity of conveyor  122 , it will engage log turner  124 , that is of known construction, that will both convey the log towards apparatus  10  and rotate the log about its own log axis according to a desired angular position. Thus, a log L entering apparatus  10  will have a desired angular position relative to the log&#39;s own longitudinal axis.  
         [0060]    Log L will be conveyed through apparatus  10  by means of its gradual engagement between rollers  50 ,  51  that are powered into rotation by their respective motors  55 ,  56 . The optional spikes on the roller outer surfaces help prevent the rollers from slipping on the log surface and ensure proper conveyance of log L along the apparatus longitudinal axis  11 . More particularly, the top rollers  50  will initially be positioned at a topmost limit position, and the bottom rollers  51  will initially be positioned at a lowermost limit position. As log L enters the apparatus upstream end  10   a , the first pair of top and bottom rollers  50 ,  51  will be displaced by their respective actuators  44 ,  45  towards log L to engage the log outer surface. The rotating rollers  50 ,  51 , pivotally biased by means of their respective arms  42 ,  43  against the log outer surface with actuators  44 ,  45 , will consequently frictionally move log L along longitudinal axis  11 . A similar action will successively occur with all pairs of rollers  50 ,  51  downstream of the first, upstream pair of rollers  50 ,  51 .  
         [0061]    The initial and subsequent engagement of all rollers  50 ,  51  against the outer surface of log L will be determined by computer  100 . Thus, the vertical displacement of rollers  50 ,  51  for engaging the outer surface of log L may be accomplished differently for different log shapes. This will help provide a proper conveyance of log L along longitudinal axis  11  notwithstanding particular log shapes. As log L advances along longitudinal axis  11 , rollers  50 ,  51  are thus likely to move vertically in an up-and-down motion, to compensate for the often irregular log shape, according to the control exercised by control center  110  on actuators  44 ,  45 .  
         [0062]    Also, as log L advances along longitudinal axis  11 , it will be positioned according to a predetermined downstream position (relative to apparatus  10 ) as computed by computer  100 . Indeed, sawing apparatus  126  having stationary blades, the latter will cut log L according to the linear direction in which log L is conveyed through sawing apparatus  126 . Thus, once the virtual three-dimensional model of log L is accomplished and an optimal yield is determined by computer  100 , an optimal log downstream position will be determined which will allow log L to be conveyed through sawing apparatus  126  to cut log L to obtain the computed optimal yield.  
         [0063]    This predetermined downstream position of log L relative to apparatus  10 , will be obtained by adjusting the horizontal and vertical position of log L as it is conveyed by apparatus  10 . The vertical adjustment of the log position will be accomplished by vertically independently moving rollers  50 ,  51  by means of actuators  44 ,  45  as explained hereinabove. The horizontal adjustment of the log position will be accomplished by horizontally and transversely independently moving roller units  30  by means of actuators  40 . Thus, the position of log L and its angle of incidence, as it is discharged at the downstream end  10   b  of apparatus  10  towards sawing apparatus  126 , will be set according to the predetermined downstream position, to obtain the optimal computed wood yield from log L.  
         [0064]    Considering that log L may be accidentally displaced by rollers  50 ,  51  in an effective real position that would be different than an anticipated computed position of log L, the co-operating pairs of monitoring scanners  60   a ,  60   b  will help correct such a deficient log positioning. Indeed, as log L moves along longitudinal axis  11 , each pair of monitoring scanners  60   a ,  60   b  will scan a detection plane intersecting the log channel and thus allowing control center  110  to verify the real position of log L upstream of each roller unit  30 . If the real position of log L, as determined by the pairs of co-operating scanners  60   a ,  60   b , is different from the anticipated position of log L, then control center  110  will command actuators  44 ,  45  and/or  40  to move rollers  50 ,  51  vertically and/or transversely to correct the position of log L in real-time.  
         [0065]    In order to perform maintenance tasks on sawing apparatus  126 , apparatus  10  has been provided with a downstream bench  22 , referred to as bench  22 - 1  in the annexed FIGS. 2 and 3, that is wider than the other benches  22 . Consequently, the downstream roller unit  30  (referred to as roller unit  30 - 1  in FIGS. 2 and 3) can be shifted to a lateral limit position which allows it to clear the central downstream end portion of apparatus  10 , in order to allow a human operator to step onto bench  22 - 1  to perform maintenance tasks on sawing apparatus  126  or within positioning apparatus  10 .  
         [0066]    Suitable power means (not shown) are connected to actuators  40 ,  44 ,  45 , roller motors  55 ,  56 , control center  110 , conveyor  122 , log-shape scanner  120 , log turner  124 , monitoring scanners  60   a ,  60   b , sawing apparatus  126 , and any other element that might require power.  
         [0067]    In an alternate embodiment of the invention (not shown in the appended drawings), instead of having two rows of rollers (a top row of rollers formed by four longitudinally consecutive rollers  50  and a bottom row of rollers formed by four longitudinally consecutive rollers  51 ), the positioning and conveying apparatus of the present invention could comprise a single bottom row of four longitudinally consecutive rollers fixed to open frame  12 . This bottom row of rollers would still be controlled by rotation inducing motors similar to motors  55 , and could thus be rotated to convey a log on their upper load-bearing surface from upstream end  10   a  to downstream end  10   b  of the apparatus. In this alternate embodiment, the rollers forming the single bottom row of rollers would still be displaceable transversally to longitudinal axis  11 , and vertically, to achieve predetermined downstream position of log L.