BACKGROUND

1. Field

This disclosure relates generally to processing of harvested logs and more specifically to an apparatus, method and system for sorting logs into diameter ranges.

2. Description of Related Art

Harvested logs from forestry operations are typically transported to a sawmill by train or truck. Batches of logs arriving at the yard of the sawmill may vary considerably in diameter and length. The logs in the yard may be handled by one or more log loaders that use a grapple to pick up batches of logs and deliver the logs sawmill equipment for processing. Due to the size of logs and the nature of the loading equipment it is not practical to perform any individual sorting and in most cases sawmill processing must be able to handle a fairly wide range of different log dimensions. Sawmill processing generally involves debarking the logs and then processing the logs through a canter line to cut the logs into cants. A cant is a piece of wood that has been sawn on at least three sides. Cants may be further processed into dimensional lumber. Modern canter lines are generally highly automated and can adapt their setup for differences between logs on the fly. Each log may be passed through a scanner that determines how to best to orient and cut the log for optimal yield or utilization. The log is then oriented according to the scanner determination and passed to the canter, which is also set up in accordance with the scanner determination. Since it may be necessary to frequently change setup between logs, the throughput of logs through a canter line may be limited. Canter setup changes takes a finite time and the individual logs in the log feed thus need to be fed through the canter line with sufficient spacing between logs to accommodate the setup change time. This spacing may in some instances be 10 - 14 feet.

SUMMARY

In accordance with one disclosed aspect there is provided a log sorting apparatus. The apparatus includes a conveyor having a receiving end for receiving a feed of singulated logs, the conveyor being operable to transport each log in a lengthwise orientation from the receiving end to one of a plurality of discharge locations along the conveyor. Each discharge location includes a longitudinal conveyor section and is associated with a range of log diameters. The apparatus also includes a log diameter sensor disposed proximate the receiving end of the conveyor and operable to determine a log diameter for each log received at the receiving end of the conveyor. The apparatus further includes a plurality of actuators, each actuator associated with at least one discharge location and selectively actuable by a controller to laterally discharge logs from the longitudinal conveyor section that fall within the range of diameters associated with the discharge location.

Each actuator may include at least one arm that exerts a lateral force on the log when actuated by the controller to cause the lateral discharge of the log at the discharge location.

Each actuator may further include a hydraulic cylinder coupled to the at least one arm.

Each conveyor section may be associated with a first discharge location to a first lateral side of the conveyor section and a second discharge location to a second lateral side of the conveyor section and each respective actuator may be selectively operable to discharge logs in a first diameter range to the first lateral side of the conveyor section and to discharge logs in a second diameter range to the second lateral side of the conveyor section.

Each actuator may include a first arm disposed to engage a side of the log opposite to the first lateral side when actuated and a second arm disposed to engage a side of the log opposite to the second lateral side when actuated and the first arm and second arm may be disposed to permit the log to pass between the first and second arms when not actuated.

The actuator may include a horseshoe shaped body having the first arm and second arm disposed on open ends of the horseshoe shaped body.

The apparatus may include a frame disposed at each discharge location, the frame being operable to receive and accumulate logs discharged from the conveyor at the discharge location.

The frame may include a plurality of pairs of crossed beams, each pair of crossed beans being spaced apart from an adjacent pair of crossed beams along the longitudinal conveyor section and forming a bunk for receiving discharged logs. The crossed beams may be spaced to permit access of a grapple of a loader to simultaneously grasp a plurality of logs accumulated in the bunk.

Each log may be spaced apart from other logs in the feed of singulated logs by a spacing distance and may further include at least one proximity sensor disposed at each discharge location along the conveyor, the proximity sensor being operable to generate a proximity signal for tracking movement of each log along the conveyor, and the controller may be operably configured to receive the proximity signal and cause the actuator to discharge each log at one of the discharge locations having an associated log diameter range corresponding to the determined diameter of the log.

The apparatus may include a feeder disposed at the receiving end of the conveyor and operably configured to receive pluralities of logs from a loader and to singulate the logs to provide the feed of singulated logs at the receiving end of the conveyor.

The feeder may include a log deck and a step feeder, the log deck being operably configured to receive the pluralities of logs from the loader and transport the logs to the step feeder, the step feeder being operably configured to separate and deliver singulated logs to the receiving end of the conveyor.

The conveyor may include a mill chain extending between a first sprocket disposed at the receiving end of the conveyor and a second sprocket disposed at an end of the plurality of longitudinal conveyor sections, at least one of the first and second sprockets being driven by a motor to cause the mill chain to be advanced to transport the logs along the conveyor.

The mill chain may include a plurality of v-blocks mounted on and spaced apart along on the mill chain and having an angle selected to receive and support each singulated log at the receiving end for transport along the conveyor while facilitating lateral discharge of the logs at the respective discharge locations.

The log diameter sensor may include a light curtain operably configured to optically measure the diameter of each log transported past the sensor.

In another disclosed aspect a system for processing harvested logs into lumber is disclosed. The system may include the log sorting apparatus above that is operable to sort logs into pluralities of sorted logs having a diameter within a range of diameters. The system also includes at least one debarking apparatus, configured to remove bark from each sorted plurality of logs loaded at one of the discharge locations. The apparatus further includes at least on canter line operable to receive one of the sorted pluralities of debarked logs and to cut the logs into cants, the at least one canter line having been previously configured to process logs within one of the diameter ranges.

A spacing between successive logs in the sorted plurality of debarked logs on the canter line may be less than about 18 inches.

In accordance with another disclosed aspect there is provided a method for sorting logs for processing in a sawmill. The method involves receiving a feed of singulated logs at a receiving end of a conveyor, the conveyor being operable to transport each singulated log in a lengthwise orientation from the receiving end along the conveyor. The method also involves determining a diameter of each singulated log received at the receiving end of the conveyor, and causing each log to be discharged from the conveyor at one of the plurality of locations along the conveyor, each location being associated with a range of diameters.

In accordance with another disclosed aspect there is provided a method for processing harvested logs into lumber. The process involves sorting the logs in accordance with the method above into pluralities of sorted logs having a diameter within a range of diameters. The method further involves debarking each sorted plurality of logs loaded at one of the discharge locations. The method also involves receiving one of the sorted pluralities of debarked logs on a canter line operable to cut the logs into lumber, the at least one canter line having been previously configured to process logs within one of the diameter ranges.

Other aspects and features will become apparent to those ordinarily skilled in the art upon review of the following description of specific disclosed embodiments in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate disclosed embodiments,

Figure 1 is a plan view of a log sorting apparatus in accordance with a first disclosed embodiment; Figure 2 is a perspective view of one of a plurality of supports making up a conveyor of the log sorting apparatus shown in Figure 1;

Figure 3 is a perspective view of a plurality of the supports shown in Figure 2 configured to provide two successive longitudinal conveyor sections;

Figure 4 is a schematic view of a control system for controlling the log sorting apparatus shown in

Figure 1;

Figure 5 is a process flowchart showing block of codes for directing a microprocessor based controller of the control system shown in Figure 4 to control operation of the log sorting apparatus;

Figure 6 is a table representing values stored in a memory of the controller while implementing the process shown in Figure 5;

Figure 7 is a table showing possible ranges of diameter associated with each of a plurality of discharge locations implemented by the log sorting apparatus; and

Figure 8 is a block diagram of a system for processing harvested logs into lumber.

DETAILED DESCRIPTION

Referring to Figure 1, a log sorting apparatus in accordance with a disclosed embodiment is shown in plan view generally at 100. The log sorting apparatus 100 may be located at a sawmill for processing harvested logs. The log sorting apparatus 100 includes a conveyor 102 having a receiving end 104 for receiving a feed of singulated logs, where a singulated log (such as the log shown at 106) is a log that has been separated from other logs. The conveyor 102 is operable to transport each log in a lengthwise orientation (i.e. in the direction of arrow 108) from the receiving end 104 to one of a plurality of discharge locations 110 - 116 along the conveyor. In the embodiment shown the conveyor 102 is implemented using an endless mill chain 150 having a plurality of links 152 and log supports 154 attached to the links for supporting the logs for transport along the conveyor 102. The mill chain 150 extends around a first sprocket 156 at the receiving end 104 and a second sprocket 158 located at a distal end of the conveyor 102 and is driven by an electric motor 160 at the second sprocket to cause the mill chain to advance to transport logs along the conveyor 102. In this embodiment the log supports 154 are configured as v-blocks mounted on and spaced apart along on the mill chain 150. The singulated logs may be rolled onto the v-blocks at the receiving end 104 of the conveyor 102. The v-blocks have support faces at an angle selected to retain the log in the support 154. Each singulated log would thus be received and supported by a plurality of the v-block log supports 154 at the receiving end 102 for travel along the conveyor while also facilitating lateral discharge of at the respective discharge locations 110 - 116.

Each of the discharge locations 110 - 116 extends along a longitudinal conveyor section. In the embodiment shown in Figure 1 the discharge locations 110 and 112 share a longitudinal conveyor section 118 and the discharge locations 114 and 116 share a longitudinal conveyor section 120. The discharge locations 110 and 114 are to a first lateral side of the conveyor sections 118 and 120 while the discharge locations 112 and 116 are to a second lateral side of the conveyor sections. In other embodiments only a single discharge location may be associated with each longitudinal conveyor section.

The log sorting apparatus 100 also includes a log diameter sensor 122 disposed proximate the receiving end 104 of the conveyor 102. The log diameter sensor 122 is operable to determine a log diameter for each log received at the receiving end 104 of the conveyor. In the embodiment shown a log 124 is currently passing over the sensor 122, which scans and determines a diameter of the log. In one embodiment the sensor 122 may be a ScanMeg Type HD light curtain scanner available from ScanMeg of Boisbriand, Quebec Canada. The ScanMeg light curtain scanner is able to measure a wide range of log diameters to an accuracy of about 1 mm using infrared light beams. In other embodiments the log diameter sensor may be implemented using a sensor based on other optical or non-optical measuring technology.

The log sorting apparatus 100 further includes a plurality of actuators selectively actuable to laterally discharge logs from the longitudinal conveyor section that fall within the range of diameters associated with the discharge location. In the embodiment shown, a plurality of actuators 126 are disposed along the longitudinal conveyor section 118, in this case associated with both the discharge location 110 and the discharge location 112.

In the embodiment shown in Figure 1 the longitudinal conveyor section 118 is made up of four similar supports 130, 132, 134, and 136, which support the conveyor 102 and the actuators 126. Referring to Figure 2, the support 130 is shown in perspective view. The support 130 includes a concrete base 200, which rests on the ground and to which a pair of upright beams 202 are mounted. The support 130 also includes a cross plate 204 attached to upper ends of the upright beams 202. In this embodiment, the actuator 126 is implemented as a horseshoe shaped kicker 206 having a first arm 208 and a second arm 210 disposed on open ends of a horseshoe shaped body. The kicker 206 is pivotably mounted on a shaft 212 extending outwardly from the cross plate 204 and is able to pivot in either direction, as indicated by the arrow 214, thus causing the arms to move in a generally lateral direction with respect to the conveyor 102. The kicker 206 is actuated by a hydraulic cylinder 216, which receives a flow of hydraulic fluid from a hydraulic system (shown in Figure 4) causing a piston rod 218 to extend or retract to cause the kicker 206 to rotate anticlockwise to the right or clockwise to the left. The arms 208 and 210 are disposed to exert a generally lateral force on a log when the kicker 206 is rotated, thus causing lateral discharge of the log. Following discharge of the log, the hydraulic cylinder 216 is operated to return kicker 206 to an unactuated or centrally oriented position, which permits logs to pass between the first and second arms 108 and 210.

In this embodiment the support 130 further includes pair of beams 220, 222 and 224, 226 mounted in a crossed or "X" configuration on each lateral side of the support. The crossed beams 220, 222, 224 and 226 of the support 130 together with spaced apart beams of adjacent supports 132, 134 and 136 form a frame or bunk for receiving laterally discharged logs from the conveyor section 118. In the embodiment shown there are four laterally disposed bunks 140, 142, 144, and 146 (labeled in Figure 1 as bunks 1A, IB, 2A and 2B respectively). The crossed beams of each bunk 140 - 146 are spaced apart to permit access for a grapple of a loader to simultaneously grasp a sorted plurality of logs accumulated in the bunk. Each bunk 140 - 146 accumulates logs discharged at the respective discharge locations 110 - 116. Logs accumulated in the bunks 140 - 146 may be conveniently loaded by a logging grapple of a log loader for further processing as a sorted plurality of logs, which will have diameters that fall within the range associated with the discharge location.

Still referring to Figure 2, the mill chain 150 of the conveyor 102 (a portion of which is shown in Figure 2) passes through a central opening in the horseshow shaped kicker 206 between the pair of arms 208 and 210. The support 130 further includes upper and lower chain supports 230 and 232, each configured as a U-channel beam extending along the conveyor 102 between adjacent supports. The upper chain support 230 is attached to the cross plates 204 and the lower chain support 232 is attached between the pair of upright beams 202 below the kicker 206. ln the embodiment shown in Figure 1 the longitudinal conveyor section 118 includes four supports 130, 132, 134, and 136 and the longitudinal conveyor section 120 also includes four similar supports. The longitudinal conveyor sections 118 and 120 are shown in perspective view in Figure 3 with the mill chain 150 being omitted in the Figure for sake of clarity. Referring to Figure 4, each of the supports 130 - 136 are configured as shown in Figure 2, except that the support 136 has the kicker 206 mounted behind the cross plate 204. The kickers 206 of each of the supports 130 - 136 may also not be regularly spaced along the conveyor 102. For example the kicker 206 of the support 130 may be spaced about 5 feet from the kicker of the support 132, which is spaced about 4 feet from the kicker of the support 134. The kicker of the support 136 is spaced apart from the kicker of the support 134 by about 5 feet. The longitudinal conveyor sections 118 and 120 are similarly configured for discharging logs of different length, in one embodiment between about 8 feet and 20 feet in length.

In the embodiment shown in Figure 1, the log sorting apparatus 100 includes a feeder 168 for providing a feed of singulated logs to the receiving end 104 of the conveyor 102. In the embodiment shown the feeder 168 includes a log deck 170 and a step feeder 172. The log deck 170 is operably configured to receive batches of logs from a log loader (not shown) and includes a conveyor 174 driven by a motor 176 that transports the logs to the step feeder 172. The step feeder 172 has a mechanism that separates the logs and conveys individual logs to the receiving end 104 of the conveyor 102. In one embodiment the step feeder 172 may be implemented using a double acting step feeder available from Linden Fabricating Ltd. of Prince George, BC, Canada. In one embodiment the conveyor 102 runs at a conveyor speed of about 450 feet per minute.

While only two longitudinal conveyor sections 118 and 120 are shown in Figure 1 and Figure 3, in practice additional longitudinal conveyor sections may be implemented to provide any desired number of discharge locations and bunks. For example, in one embodiment 5 longitudinal sections of conveyor may be arranged end-to-end to implement a log sorting apparatus having ten bunks. The number of bunks may be selected in accordance with a range of harvested log diameters typically received at the sawmill and also based on the canter lines available at the sawmill for processing logs.

Referring back to Figure 1, the log sorting apparatus 100 also includes a proximity sensor 164 disposed at the discharge location 110, 112 along the conveyor 102. The proximity sensor generates a proximity signal for tracking movement of the logs along the conveyor. The proximity sensor 164 generates proximity signals indicating whether or not a log is proximate the sensor. In one embodiment the feeder 168 is configured to cause each log in the feed of singulated logs traveling along the conveyor 102 to be relatively closely spaced, typically by a spacing distance of about 12 inches and no more than 18 inches. The signal generated by the proximity sensor 164 will thus having either a first state indicating that a log is in front of the sensor or a second state indicating that a space between logs is in front of the proximity sensor. A further proximity sensor 166 is disposed at the beginning of the conveyor section 120 ahead of the discharge locations 114, 116. In one embodiment the proximity sensor 164 and the proximity sensor 166 may be implemented using a Q4X photoelectric proximity sensor available from Banner Engineering Corp., Minneapolis, MN, USA.

A control system for controlling the log sorting apparatus 100 is shown in Figure 4 at 400. The control system 400 includes a controller 402 having an interface 404 for receiving log diameter signals from the log diameter sensor 122, and an interface 406 for receiving proximity signals from proximity sensors 164 and 166. In one embodiment the controller 402 may be implemented using a microprocessor based controller circuit, which would generally include a microprocessor and memory such as RAM memory for storing data during operation and/or a flash memory for storing program codes for configuring the controller to perform control functions.

The control system 400 also includes a hydraulic valve 410, a hydraulic fluid pump 412, and a hydraulic fluid reservoir 414. The controller 402 also includes an interface 408 for producing control signals for controlling operation of the hydraulic pump 412 and the valve 410 via a solenoid 416. The valve 410 is responsive to electrical signals received from the interface 408 at the solenoid 416 to switch between three valve states.

In a first state illustrated by the central valve symbol 418, when the hydraulic pump 412 is actuated by the control signal received from the interface 408, hydraulic fluid is drawn from the reservoir 414 via a line 420 and returned to the reservoir via a line 422. No fluid is delivered to the hydraulic cylinder 216.

In a second state illustrated by the right hand valve symbol 424, the hydraulic fluid drawn from the reservoir 414 is passed through the valve 410 to a first port 430 of the hydraulic cylinder 216. At the same time, hydraulic fluid is discharged through a second port 432 of the hydraulic cylinder 216 and returned via the valve 410 to the reservoir 414. Under these conditions the piston rod 218 of the hydraulic cylinder 216 extends causing the kicker 206 to rotate anticlockwise about the shaft 212. In a third state illustrated by the left hand valve symbol 426, the hydraulic fluid drawn from the reservoir 414 is passed through the valve 410 to a second port 432 of the hydraulic cylinder 216. At the same time, hydraulic fluid is discharged through the first port 430 of the hydraulic cylinder 216 and returned via the valve 410 to the reservoir 414. Under these conditions the piston rod 218 of the hydraulic cylinder 216 retracts causing the kicker 206 to rotate clockwise about the shaft 212.

In one embodiment each of the supports 130 - 136 associated with the conveyor sections 118 may be connected to the same valve 410 and controlled by the control system 400 to operate the respective hydraulic cylinders 216 together. In other embodiments each support 130 - 136 may have its own valve 410 to permit individual control of the kickers associated with the supports. This would have the advantage of only actuating kickers that were necessary to discharge the log at one of the discharge locations 110 - 116 based on the length of the log. The length of the log may be determined either at the log diameter sensor 122 or by the proximity sensors 164 and 166, based on the conveyor speed.

In one embodiment the controller 402 and interfaces 404, 406, and 408 may be implemented using a microprocessor based programmable logic controller (PLC), such as the Allen-Bradley ControlLogix 5580 Controller available from Rockwell Automation Inc. of Wisconsin, U.S.A. The Allen-Bradley ControlLogix 5580 PLC may be combined with various interface modules to provide the required functionality for monitoring the sensors and controlling the hydraulics as shown in Figure 4. The interfaces 404, 406, and 408 may be implemented using off-the-shelf interface modules suitable for interfacing with the respective log diameter sensor 122, the proximity sensor 164, the proximity sensor 166, valve 410, and hydraulic pump 412. The signals from the sensors may be received at the interface as digital signals (for example RS - 522 serial signals or other signal formats) or analog signals (for example, 4-20 mA output signals or other signal formats).

Referring to Figure 5, a flowchart depicting blocks of code for directing a microprocessor based controller 402 to control the log sorting apparatus 100 is shown generally at 500. The blocks generally represent program codes that may be read from a computer readable medium such as a flash memory device for directing the microprocessor to perform various functions related to log sorting. The actual code to implement each block may be written in any suitable programming program language, such as Ladder Diagram, Structured Text), Function Block Diagram, Instruction List, Sequential Flow Chart, used for PLC programming or any other programing language.

The process begins at 502, where the controller 402 is initialized. Block 502 may direct the microprocessor to load the program codes, perform internal checks, and establish communication with the sensors 122, 164, 166, the hydraulic pump 412, and valve 410. Block 502 also directs the microprocessor to produce signals at the interface 408 for activating the hydraulic pump 412 and to place the valve 410 in the first state 418, where no fluid is being delivered to the hydraulic cylinder 216. Under these conditions the kicker 206 would remain centered as shown in Figure 2 and logs are free to pass between the pair of arms 208 and 210 along the conveyor 102. Block 504 then directs the microprocessor to initiate three process threads 504, 506, and 508, which are described below and run in parallel during operation of the log sorting apparatus 100.

The process thread 504 directs the microprocessor of the controller 402 to receive and record log diameters and starts at block 510. Block 510 directs the microprocessor to receive signals from the log diameter sensor 122 at the interface 404, and based on the received signals to determine whether a log is passing over the diameter sensor. In one embodiment the step feeder 172 causes singulated logs to be spaced apart by about 12 - 18 inches. When a log (such as the log 124 in Figure 1) passes from the receiving end 104 of the conveyor over the diameter sensor 122, the sensor will detect the presence of the log begin producing an output signal representing the diameter of the log. When no log is located over the log diameter sensor 122 the output of the sensor log diameter sensor 122 will produce a signal indicating that there is a gap between singulated logs (i.e. a no-diameter state). If at block 510 it is determined that no log is detected at the log diameter sensor 122 then the microprocessor is directed to repeat block 510. If at block 510 it is determined that a log diameter is being detected at the diameter sensor 122 then the microprocessor is directed to block 512.

Block 512 directs the microprocessor to receive the diameter signal and extract a diameter value provided by the log diameter sensor 122. Block 514 then directs the microprocessor to again determine whether the signal currently being received from the log diameter sensor 122 indicates that there is still a log above the sensor, in which case the microprocessor is directed back to block 512 to read and average the received log diameter. If at block 514 the signal produced by the log diameter sensor 122 has a no-diameter state then the log has been transported away from the sensor 122 indicating the presence of a gap between singulated logs. By detecting the spaces between logs (provided through operation of the step feeder) the controller 402 is able to assign individual diameters to each singulated log in the feed. Block 514 then directs the microprocessor to block 516 where the average log diameter is recorded in the memory of the controller 402. In one embodiment a sequence number may also be assigned to each singulated log and the average log diameter may be recorded along with the log sequence number in a memory of the controller 402. An example of diameter values stored in memory is shown in Figure 6 represented by a table 600, where the log 124 has been assigned a sequence number of 1 and a diameter of 18.5 inches. Block 516 then directs the microprocessor to block 518, where the sequence number is incremented and the microprocessor directed back to block 510 to await the next singulated log. As shown in Figure 6, the process thread 504 results in the memory table 600 being populated with a sequence of averaged log diameters for each of the singulated logs 124 and 106 and for subsequent singulated logs in the feed.

The process thread 506 that runs in parallel with the process thread 504 starts at block 520. Block 520 directs the microprocessor to receive the proximity signal from the proximity sensor 164 and to determine whether a log is being detected at the proximity sensor 164. As shown in Figure 1, the proximity sensor 164 is located at a point along the conveyor 102 ahead of the longitudinal conveyor section 118. When the signal received from the proximity sensor 164 indicates that no log is currently being transported past the sensor, block 520 directs the microprocessor to repeat the block. When at block 520 the sensor indicates that a log has been detected at the sensor, the microprocessor is directed to block 522. Block 522 directs the microprocessor to determine whether the log has been transported past the proximity sensor 164. When the signal produced by the proximity sensor 164 changes to indicate that no objects are detected within the range of the sensor, a gap between the logs is currently passing the sensor. Accordingly, when at block 522 a log is still detected, the microprocessor is directed back to block 522. When at block 522 a log is no longer detected, the microprocessor is directed to block 524. Once the log passes the proximity sensor 164 the log will generally extend along the longitudinal conveyor section 118.

Block 524 directs the microprocessor to determine whether the log diameter of the log currently disposed on the longitudinal conveyor section 118 matches the diameter range of the Bunk A (140). Referring to Figure 7, as an example, the bunks 140 - 146 may be assigned log diameter ranges as set out in the table 700. Smaller diameter logs in this embodiment are discharged to the right to bunks IB (logs less than 8 inches in diameter) and 2B (logs more than 8 inches but less than 13 inches in diameter). Larger diameter logs are discharged to the left to bunks 1A (logs greater than 18 inches in diameter) and 2A (logs more than 13 inches but less than 18 inches in diameter). Other log ranges may be established depending on the nature of logs being processed and the further processing requirements of the sawmill.

Block 524 then directs the microprocessor to read the next log in sequence in the memory table 600 shown in Figure 6. In the example shown, the next singulated log is the log 124 having an assigned sequence of "1" and a measured average diameter of "18.5", which falls within the bunk 1A diameter range. Block 524 thus directs the microprocessor to block 526. Block 526 directs the microprocessor to cause signals to be produced at the interface 408 to place the valve 410 in the second state 424 resulting in the hydraulic cylinder 216 being extended and the kicker 206 rotated anticlockwise about the shaft 212 such that the arm 210 engages the log 224. Referring back to Figure 3, the log 124 is shown at the conveyor section 118 and the hydraulic cylinders 216 have been extended at each of the supports 130 - 136 to cause the kickers 206 to rotate anticlockwise about the shaft 212. The rotation of the kickers 206 causes the respective arms 210 to engage and discharge the log laterally into the bunk 1A (140). The plurality of actuators 126 ensures that the log is discharged in an orientation generally parallel to the conveyor 102. A log 302, also falling within the diameter range for bunk 1A, has been previously discharged at the discharge location 110 and is supported within the beams 220 and 222 of the bunk.

Block 532 then directs the microprocessor to cause the valve 410 to be placed in the third state 426 retracting the piston rod 218 of the hydraulic cylinder 216 and returning the kicker 206 to the central orientation. The process 506 then continues at block 534, which directs the microprocessor to flag the log as having been discharged from the longitudinal conveyor section 118 of the conveyor 102. In one embodiment the entry for the log 124 in the memory table 600 (Figure 6) may be deleted from memory, indicating that the log has been discharged. In other embodiments, the entry for the log 124 may include an additional flag (not shown) indicating that the log has been discharged. Block 534 then directs the microprocessor back to block 520 and the process 506 is repeated for the next log in the log feed.

If at block 524 the log does not fall within the diameter range of bunk 1A, the microprocessor is directed to block 528. Block 528 directs the microprocessor to determine whether the log falls within the diameter range of bunk IB. If the log also does not fall within the diameter range of bunk IB, block 528 directs the microprocessor back to block 520. In this case the kickers 206 of the conveyor section 118 remain centered and the log is transported through the conveyor section to the next conveyor section 120. If at block 528, the log falls within the diameter range of bunk IB, the microprocessor is directed to block 530. Block 530 directs the microprocessor to cause signals to be produced at the interface 408 to place the valve 410 in the third state 426. This would result in the hydraulic cylinder 216 being retracted and the kicker 206 rotated clockwise about the shaft 212 such that the arm 208 engages the log 224. The microprocessor is then directed to blocks 532 and 534, which as described above return the kicker 206 to a central orientation and flag the log as having been discharged.

The control system 400 also implements the process thread 508, which is identical to the process 506 but operates on the second proximity sensor 166 and for the conveyor section 120. When determining whether the log is within the diameter range of the bunks at blocks 536 and 540, the diameter of the log having the lowest sequence number in the memory table 600 is read. Since any discharged logs will have been flagged as such, the log at the longitudinal conveyor section 120 should be the log in the memory table 600 having the lowest sequence number. Additional logic may be necessary to resolve possible conflicts in the event that a log diameter is read from the memory table 600 by either of blocks 524 and 526 at the same instant as a log diameter is being read from the memory table 600 by either of blocks 536 and 540.

In embodiments having additional longitudinal conveyor sections, the process thread 406 would be implemented for each additional section to cause logs that fall within the diameter range associated with each section to be discharged laterally to either the left or right at the applicable discharge locations.

The embodiments of the log sorting apparatus 100 disclosed above thus provide a sorting apparatus that may be easily configured to suit the range of logs being received at a sawmill.

A system for processing harvested logs into lumber incorporating the log sorting apparatus 100 shown in Figures 1 - 4 is shown in Figure 8 at 800. Referring to Figure 8, the system 800 includes the log sorting apparatus 100 and controller 402 as described above that operates to sort logs into pluralities of sorted logs having a diameter within a range of diameters. In the embodiment shown the system further includes a first debarking apparatus 802 and a second debarking apparatus 802 which operate to remove bark from the sorted pluralities of logs. In one embodiment a log loader will load logs from one of the bunks 140 - 146 and transport the logs to one of the debarkers 802 or 804. Flaving more than one debarker provides some redundancy in the event of a failure and also provides additional capacity for debarking. The system 800 also includes a canter line 806. The canter line receives debarked and cuts the logs into lumber. Modern canter lines are generally highly automated and can be set up to handle logs having quite substantial differences in diameter by reconfiguring saw blades to obtain a desirable lumber yield from each log. In one embodiment the controller 402 may communicate sorted diameter range date to the canter line to permit configuration prior to the logs being received from processing into lumber. One advantage of the system 800 in including the log sorting apparatus 100 is that sorted pluralities of logs within one of the diameter ranges may be fed through the canter line 806 in batches. This facilitates setup of the canter line for optimal utilization of the logs and also permits the logs to be fed to the canter line 806 with minimal spacing between logs (typically less than about 18 inches). In some prior systems where logs are fed to the canter line 806 unsorted, the line must sense the diameter of each log and configure for optimal utilization. This places a practical limitation on the spacing between logs, in many cases requiring that the feed of logs have a separation of many feet, and typically about 14 feet depending on the capability of the canter line automated setup process. The disclosed embodiments provide a log sorting apparatus that improves the overall efficiency of operating a sawmill system such as shown in Figure 8 and also facilitates increased productivity of the canter line 806. The canter line 806 is usually associated with a high capital cost and complex setting procedures. In contrast the log sorting apparatus 100 would involve a significantly lower capital cost and has comparatively low complexity and simpler maintenance when compared to the canter line. The disclosed log sorting apparatus 100 thus has the potential for significantly improving operating efficiency of the sawmill system.

While specific embodiments have been described and illustrated, such embodiments should be considered illustrative only and not as limiting the disclosed embodiments as construed in accordance with the accompanying claims.