WO2009072968A1 - Procédé et agencement de classification de grumes - Google Patents

Procédé et agencement de classification de grumes Download PDF

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Publication number
WO2009072968A1
WO2009072968A1 PCT/SE2008/051389 SE2008051389W WO2009072968A1 WO 2009072968 A1 WO2009072968 A1 WO 2009072968A1 SE 2008051389 W SE2008051389 W SE 2008051389W WO 2009072968 A1 WO2009072968 A1 WO 2009072968A1
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WO
WIPO (PCT)
Prior art keywords
log
transducers
arrangement
positioning
acoustic
Prior art date
Application number
PCT/SE2008/051389
Other languages
English (en)
Inventor
Håkan Lindström
Simon Forslund
Ping Wu
Original Assignee
A-Sort Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by A-Sort Ab filed Critical A-Sort Ab
Publication of WO2009072968A1 publication Critical patent/WO2009072968A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/46—Wood
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
    • B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
    • B07C5/04—Sorting according to size
    • B07C5/12—Sorting according to size characterised by the application to particular articles, not otherwise provided for
    • B07C5/14—Sorting timber or logs, e.g. tree trunks, beams, planks or the like
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/04—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness specially adapted for measuring length or width of objects while moving
    • G01B11/043—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness specially adapted for measuring length or width of objects while moving for measuring length
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/08—Measuring arrangements characterised by the use of optical techniques for measuring diameters
    • G01B11/10—Measuring arrangements characterised by the use of optical techniques for measuring diameters of objects while moving
    • G01B11/105—Measuring arrangements characterised by the use of optical techniques for measuring diameters of objects while moving using photoelectric detection means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B17/00—Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations

Definitions

  • the present invention generally relates to handling of saw logs, and in particular to a method and means for classification of logs based on their material properties.
  • the transmitters and receivers are provided in a radial direction through the bark of the log into the outer rim of the wooden part in order to transmit or receive acoustic signals properly. In such a way, radial gradients of impulse velocity can be obtained, which are indicative of log quality.
  • An automatic log handling system is suggested, where the log is transported to an analysis position, at which transmitters and receivers, i.e. transducers, are positioned into appropriate position in relation to the log, measurements are performed and the logs are finally classified.
  • the classification according to WO2007/011296 is basically highly reliable. However, minor problems are found in the earlier proposed system configuration. Since the transit time transducers have to penetrate the bark in order to reach the wood of the log, the transducers are exposed to a high degree of wear. This may be solved by instead placing the transducers on the sawed ends. Such a configuration, however, raises other problems.
  • the optimum position for the transducers should be close to the outer rim of the wooden part of the log.
  • the log diameters typically vary over a large interval. Normally the largest diameters can be up to 5 or 10 times larger than the smallest ones. Fixed radial positions are not very suitable, since they have to be designed for the narrowest admitted logs. Furthermore, the logs do also exhibit varying lengths. Typical intervals could be from 2.5 m to 6 m.
  • transducers need to be positioned in the axial direction individually for each log. Since the transducers are sensitive equipment, which may be destroyed if it is smashed into the log, such adjustments can not be performed with too large velocities.
  • a typical throughput rate can be in the order of 0.2 to 1 log/ s. All the positioning problems described here above, necessary for adjusting the transducer positions, may sum up in that the total positioning time corresponds to a significant part of the total time the log spends in the analysis position. The throughput of the measurement system may be severely limited by such times for positioning.
  • An objective of the present invention is to improve the maximum throughput rate of logs through an arrangement for acoustical classification of logs.
  • a further objective of the present invention is to decrease wear of transducers used for the classification measurements.
  • Yet a further objective of the present invention is to provide fast positioning of transducers at optimal positions on logs' ends.
  • a method for classifying logs comprises bringing a log into an analysis position, positioning transducers for acoustic measurements at measuring positions at the log, performing acoustic measurements on the log and classifying the log based on the acoustic measurements.
  • the positioning comprises positioning of the transducers on or at both ends of the log in an axial direction of the log and the acoustic measurements are performed between the ends of the log.
  • the method further comprises determining of outer dimensions of the log before the log is brought into the analysis position.
  • the positioning of the transducers in the axial direction is then actively controlled to get a coarse positioning based on the determined outer dimensions. This coarse positioning is performed at least partly before or concurrently to the bringing of the log into the analysis position.
  • an arrangement for classifying logs comprises a log support structure for holding a log in an analysis position and transport means for bringing the log into the analysis position.
  • Transducers of an acoustic measurement equipment for acoustic measurements are attached to transducer support structures and positionable into measuring positions at the log.
  • Electronic circuitry of the acoustic measurement equipment is connected to the transducers for performing acoustic measurements on the log and means for classifying the log is connected to the electronic circuitry of the acoustic measurement equipment.
  • the means for classifying the log is arranged for basing the classifying on an output from the electronic circuitry of the acoustic measurement equipment.
  • the transducers are positionable into measuring positions on or at both ends of the log in an axial direction of the log and the electronic circuitry of the acoustic measurement equipment is arranged for performing acoustic measurements between the ends of the log.
  • the arrangement further comprises a dimension determining arrangement, arranged for determining outer dimensions of the log before the log is brought into the analysis position.
  • the arrangement also comprises a position control for controlling a coarse position in the axial direction of the transducer support structures connected to the dimension determining arrangement.
  • the position control is arranged for controlling the coarse position in the axial direction based on an output from the dimension determining arrangement.
  • the position control is further arranged for performing the controlling at least partly before or at least partly concurrently to the log being brought into the analysis position.
  • One advantage with the present invention is that the throughput rate of logs through a log classification system can be increased considerably, being in agreement with throughput rates of other parts of a saw mill.
  • FIG. 1 is a schematic drawing of an embodiment of an arrangement for log classification according to the present invention
  • FIG. 2 is a block scheme illustrating information flows in the embodiment of Fig. 1 ;
  • FIG. 3 is a flow diagram of steps of an embodiment of a method according to the present invention.
  • FIG. 4 is a schematic drawing of an embodiment of an arrangement of a transducer holder used in the embodiment of Fig. 1 ;
  • FIG. 5 is a schematic drawing of another embodiment of an arrangement of a transducer holder
  • FIG. 6 is a schematic drawing of yet another embodiment of an arrangement of a transducer holder
  • FIG. 7 is a schematic drawing of an embodiment of an arrangement of a transducer holder based on passive radial positioning
  • FIG. 8 is a schematic drawing of another embodiment of an arrangement for log classification according to the present invention.
  • FIG. 9 is a schematic drawing of yet another embodiment of an arrangement for log classification according to the present invention.
  • FIGS. 10A-B are schematic drawings of an embodiment of an arrangement for log classification according to the present invention, based on transverse transport to and from an analysis position;
  • FIG. 11 is a block diagram illustrating principles for redundant dimensional measurements.
  • a device emitting signals is denoted a “transmitter” or an “actuator”.
  • a device sensing different impinging signals is denoted a “receiver” or a “sensor”.
  • a “transducer” is used in the present disclosure as a common term for transmitter, actuator, receiver and sensor.
  • FIG. 1 An embodiment of an arrangement 1 for classifying logs is illustrated in Fig. 1.
  • a log 2 is entered into an introduction part 10 of the arrangement 1 for classifying logs by means of an input conveyor 12.
  • the log 2 is in the present embodiment transported in an axial direction, i.e. in the longitudinal direction of the log 2.
  • the log 2 is transported through a dimension determining arrangement 16 into an analysis part 20 of the arrangement 1 for classifying logs.
  • the dimension determining arrangement 16 comprises in the present embodiment a laser scanner equipment 18, determining dimension measures of the log 2 such as diameters and length. Based on such measures, a volume of the log 2 can be determined for use in the following quality classification.
  • the dimension determining begins when the log comes into contact with a follower wheel 17 of the dimension determining arrangement 16.
  • Four laser sensors 19 measure the circumference shape of the log at equidistant positions along the log 2 as the input conveyor 12 is moving the log 2. The equidistant positions are achieved by controlling the measurement frequency based on the speed of the follower wheel 17.
  • the follower wheel 17 stops and a total rotation angle of the follower wheel 17 can easily be translated into a length of the log 2.
  • the log length and the diameter or circumference information can easily be transformed into a log volume. This information is later used for classification purposes.
  • the distribution conveyor 22 transports the log 2 into an end position, in contact with a stop plate 14, as a preparation for the following entry into an analysis position.
  • a typical time for the log to pass the dimension determining arrangement 16 and reach the stop plate 14 is between 1 and 5 seconds.
  • the log 2 is forced by side transport means 21 to the side down to a log support structure 24.
  • the log 2 rolls or slides along two input support beams 23 into an analysis position 40, and is kept in the analysis position 40 by the log support structure.
  • a stationary measurement carrier 26 is arranged at the log support structure 24 just in front of the front end of the log 2, i.e., in an axial direction 3 of the log 2.
  • a movable measurement carrier 28 is similarly arranged at the log support structure 24 just behind the back end of the log 2, i.e., also in an axial direction 3 of the log 2.
  • the stationary measurement carrier 26 and the movable measurement carrier 28 are thus placed in positions at both ends of the log 2.
  • the stationary measurement carrier 26 and/ or the movable measurement carrier 28 comprise a respective transducer holder 30.
  • each transducer holder 30 comprises a number of transducers 50.
  • a position controller 55 is arranged for controlling a coarse position of the movable measurement carrier 28 and is connected to the dimension determining arrangement 16.
  • the position controller 55 comprises a control unit 56 and means 57 for moving the transducers.
  • the position controller 55 is thereby arranged for controlling the coarse position of the movable measurement carrier 28 based on an output from the dimension determining arrangement 16. This is performed at least partly before or at least partly concurrently to the log being brought into the analysis position 40.
  • the coarse position is in this particular embodiment a coarse position of the log support structure 24 in the axial direction as well as in a coarse position of the transducers 50 in a radial direction.
  • both the stationary measurement carrier 26 and the movable measurement carrier 28 are thus already positioned relatively close to one respective end of the log 2. Fine positioning is then rapidly performed and quality analysis can commence almost immediately, when the log 2 enters into the analysis position 40.
  • An acoustic measurement equipment comprises the transducers 50 as well as an electronic circuitry 60.
  • the electronic circuitry 60 of the acoustic measurement equipment is connected to the transducers for performing the measurements.
  • Transmitters are instructed to emit acoustical signals causing vibrations propagating in the log 2.
  • the transmitters are actuators providing mechanical stress pulses onto the surface of the log end.
  • the acoustic measurement equipment 60 collects relevant information, basically concerning acoustic properties of the log from the sensors.
  • the sensors are acoustical sensors placed in mechanical contact with the log 2 in order to register vibrations therein.
  • the log support structure 24 further comprises a weighing device 34, comprising a sensor at each end of the log support structure 24, which together determines the total weight of the log 2. Combined with the volume information from the dimension determining arrangement 16, a density of the log 2 can thus be determined, and used for the classification.
  • Means for classifying 70 the log typically a processor 72, is connected to the acoustic measurement equipment.
  • the processor 72 is in the present embodiment also connected to the dimension determination arrangement 16 for achieving volume information and to the weighing device 34 for achieving weight information.
  • the processor 72 is arranged for classifying the log based on an output from the acoustic measurement equipment, and in the present embodiment also on the volume and weight information.
  • the log 2 may in the present embodiment be marked according to the classification.
  • a paint sprayer equipment 32 is instructed by the means for classifying 70 to spray paint of a suitable color on the end of the log 2.
  • a paint sprayer equipment 32 is as such well known in prior art and is therefore not further discussed.
  • a classification into three classes can be made, where one class corresponds to a white color marking, another class corresponds to a black color marking and a third class corresponds to an unmarked log end.
  • different colors and/ or color patterns may be used.
  • the color marking can be used by systems further downstream the process line to distinguish between the different classes.
  • the log 2 When analysis and any marking of the log is finished, the log 2 is released from the analysis position by turning down two exit support beams 27 arranged at the log support structure 24. The log 2 is pushed by extractor beams 29 over the exit support beams down to an exit conveyor system (not shown). A total time for entering the analysis position, making the analysis and being released is designed to be in the order of 1 to 3 seconds.
  • An important part of the present invention is to use the dimension information for a log to enable a pre-setting of the axial position of the movable transducers.
  • Such presetting makes it possible to shorten the time the log spends in analysis position. It is preferable if the entire coarse positioning is performed before or concurrently to the log being brought into the analysis position. However, also a partly performed coarse positioning will reduce the total analysis time.
  • a connection 74 between the dimension determination arrangement 16 and the means for classification 70 illustrates the flow of information.
  • Means for obtaining property parameters 71 provides results to the means for classification over a connection 75, on which results the classification is based.
  • weight information and optionally also temperature information and other auxiliary property information are provided by a connection 76 between the weighing device 34, a temperature measuring device 73 and an auxiliary property information device 77 and the means for classification 70.
  • the auxiliary property information device 77 could e.g. be the camera system discussed in connection with Fig.
  • connection 74, 75, 76 were present also in prior-art classification systems.
  • information from the dimension determination arrangement 16 is additionally used for the purpose of speeding up the mechanical operation of the arrangement.
  • dimension information is sent from the dimension determination arrangement 16 to the position controller 55 by a connection 78.
  • Fig. 3 illustrates a flow diagram of steps of an embodiment of a method according to the present invention.
  • a method for classifying logs begins in step 200.
  • outer dimension of a log is determined.
  • Transducers for acoustic measurements are positioned in step 212 into measuring position at a coming position of the log.
  • the positioning comprises positioning of the transducers at both ends of the coming position of the log in an axial direction of the log.
  • the positioning further comprises actively controlled coarse positioning of the transducers in at least the axial direction based on the determined outer dimensions.
  • the log is brought into an analysis position in step 214.
  • the coarse positioning of step 212 is performed at least partly before or concurrently to the step 214.
  • Acoustic measurements are performed on the log in step 216, whereby the acoustic measurements are performed between the ends of the log.
  • the logs are classified, based on the acoustic measurements.
  • the method ends in step 299.
  • Fig. 4 is a detailed view of an embodiment of a transducer holder 30 of a movable measuring carrier 28 that can be used in a log classification arrangement, e.g., according to Fig. 1.
  • a motor 82 is arranged at a frame 80.
  • the shaft of the motor 82 is connected to a gear 84, transferring a rotation of the shaft into a rotation of a trapezoidal screw thread rod 90 extending between the frame 80 and a centre connection box 94, provided in the centre of the frame 80.
  • the trapezoidal screw thread rod 90 is engagably positioned through a threaded hole 92 in a transducer support structure 91.
  • the transducer support structure 91 has two further holes 93, through which a pair of guiding rails are provided. Upon turning the trapezoidal screw thread rod 90, the transducer support structure 91 will move towards the centre connection box 94 or out from the centre connection box 94 depending on the rotation direction.
  • Transducers 50 in this embodiment acoustic or ultrasonic sensors 51, are mounted on the transducer support structure 91.
  • the acoustic or ultrasonic sensors 51 are mounted in a spring-loaded manner in a direction perpendicular to the frame 80 plane.
  • the movable measuring carrier 28 can thereby be moved gently towards an end of a log, and the springs will take care of any deviancies from a perpendicular cut log, whereby the acoustic or ultrasonic sensors 51 are protected from mechanical damage.
  • a motion transfer structure 83 comprises a series of rods 86, gears 84 and edge gears 85 are provided, for transmitting the rotational motion of the motor shaft to three additional sets of trapezoidal screw thread rod 90 and transducer support structures 91.
  • a total of four vibration sensors 51 are thus provided symmetrically around the centre connection box 94, controlled by one common motor 82.
  • the motor is controlled by the position controller 55 (Fig. 1), based on the information from the dimension determination arrangement 16 (Fig. 1). By knowing a diameter of the back end of the log to be classified, the motor 82 can be instructed to move the transducer support structures
  • acoustic or ultrasonic sensors 51 will be situated at the same distance from the centre of the log. Such distance is then adapted to the smallest distance of the log circumference at the back end. Typically a small safety margin will place the vibration sensors safely at the wooden part of the log, but still close to the outer bark layer.
  • Such radial adjustment of the position is according to one embodiment of the present invention performed before or at least concurrently to the log entering the analysis position.
  • the common operation of the different transducer support structures 91 is enabled due to the adoption of a circular measuring scheme. This is a suitable approach in the embodiment of Fig. 1 , since the angular direction of the log may be altered between the dimension determination and the analysis position. A longest diameter of a non-circular cross-section of an end of the log may be positioned in another direction when the log has entered into the analysis position, which is why angular information can not be used. Furthermore, the analysis of the transit time measurements is simplified by assuming that all transducers are positioned at the same distance from the centre of the log.
  • the stationary measuring carrier 26 is basically equipped in a corresponding manner. However, here the transducers 50 are instead actuator means capable of introducing acoustic/ elastic waves into the log at different positions.
  • one of the transducer support structures 91 of the stationary measuring carrier 26 additionally supports a hammer for exciting vibrations in the other support structures 91 support vibration sensors that measure the resonance frequencies of vibration.
  • the transducers may be positioned radially independent from each other.
  • Fig. 5 illustrates such a system.
  • four motors 82 are provided.
  • Each motor 82 controls the position of a separate transducer 50.
  • the position controller 55 can instruct each motor 82 separately to position the respective transducer.
  • the transducers may e.g. always be positioned at the same distance from the interface between the wood and the bark.
  • analysis generally becomes more difficult to perform.
  • Fig. 6 illustrates another embodiment of a transducer holder 30.
  • the transducer holder 30 comprises a cam disk 100 with four spiral formed slots 108 and a frame disk 102 with four straight radially directed slots 110.
  • the cam disk 100 and the frame disk 102 are mounted concentrically and rotatable with respect to each other.
  • the cam disk 100 is provided with cogs 1 12 at the out rim.
  • Four transducer support structures 91 carry different transducers 50.
  • the transducers 50 are four acoustic or ultrasonic sensors 51, three vibration sensors 53 and one actuator 58 for introducing acoustic waves into the log.
  • a guiding pin 106 is mounted in each transducer support structure 91 and passes through a respective slot 108 in the cam disk 100 and a respective slot 110 in the frame disk 102.
  • a motor (not shown) is arranged for rotating the cam disk 100 relative to the frame disk 102.
  • the motion transfer structure 83 comprises in this embodiment the slots 108, 110 and the guiding pins 106. In such a way, a radial positioning is easily obtained, where all transducers 50 are moved in the same way.
  • the radial positioning of the transducers has been performed actively based on input information from the dimension determination arrangement.
  • Such radial positioning is, in analogy with the axial coarse positioning, preferably performed before or concurrently with the entry of the log into analysis position.
  • transducer support structures 91 carry respective transducers 50.
  • the transducer support structures 91 are attached to interaction structures 120.
  • Each interaction structure 120 has an interaction surface 121 which is inclined with respect to an axial direction.
  • the interaction structures 120 are triangular, presenting a straight sloping interaction surface 121.
  • the transducer support structures 91 comprise in this embodiment two holes 126, through which a pair of guiding rails 124 are provided.
  • the guiding rails are rigidly attached in a respective end piece 123 and a common centre piece 122.
  • a spring arrangement 128 provides a small spring force onto each transducer support structure 91, to position the transducer support structure 91 in a pre-determined position if no other forces are present.
  • a transducer 50 is also provided at the common centre piece 122 and will therefore always be positioned at the centre of a log 2. This embodiment therefore uses a total of five transducers 50.
  • a log 2 is entered just in front of the transducer holder 30 of the movable measuring carrier 28 by means of the coarse positioning described further above.
  • the transducer holder 30 is then translated towards the log 2 end, i.e. in an axial direction of the log 2.
  • This translation can be provided by the same means as providing the coarse axial positioning.
  • a separate fine positioning translating means can be provided.
  • the transducer support structures 91 are thereby translated towards the log 2 end. When the interaction surface 121 of the interaction structure 122 comes into contact with the bark at the log 2 end, the transducer support structures 91 are forced outwards in a radial direction.
  • the inclination of the interaction surface 121 is thus arranged for creating a radial, outwards directed, motion of the transducers upon further translation of the transducer holder 30 when the interaction surfaces 121 come into mechanical interaction with the log 2.
  • the axial translation ends when the sensors are positioned at a suitable axial position relative to the log end. If transducers requiring mechanical contact are used, the axial translation ends when the transducers reach the log 2 end. If contact-free transducers are used, a position sensor can be used to end the fine axial positioning at a suitable distance from the log.
  • Such a final axial position will (ideally) correspond to a predetermined interaction point 129 at the interaction surface 121. Since this interaction point 129 will be supported against the bark of the log 2, the corresponding transducer will be positioned at the same, predetermined, radial distance from a circumference of the log 2 end. A fine axial positioning will preferably take place also at the opposite end of the log 2, whereby the arrangement for classifying logs based on this approach preferably comprises two movable measuring carriers 28.
  • the transducers With a movable measuring carrier 28 being positioned in the above described manner at the ends of a log with uncircular end cross-sections, the transducers will be positioned at different positions relative to the centre of the log. For detailed analysis of the acoustic properties, the analysis algorithms may have to know the actual distances from the centre.
  • the transducer support structures 91 may in such a case be provided with position sensors, being able to detect a distance from the centre of the movable measuring carrier 28.
  • the transport of the log between the dimension determination arrangement and the analysis position can be performed in a way keeping track on the rotation of the log, the shape information can be extracted from the dimension determination arrangement and transducer positions can be calculated therefrom.
  • a major time saving is made by preparing a coarse axial positioning in advance, before the log enters into the analysis position.
  • a major time saving may be insufficient. In such cases, one may have to provide multiple analysis positions.
  • FIG. 8 another embodiment of an arrangement for classifying logs 1 is illustrated.
  • an analysis position 40 is provided at each side of the input distribution conveyor 22. While analysis of one log 2 at one of the analysis positions 40 is performed, another log 2 may be entered into the other analysis position 40.
  • an effective analysis time can be reduced by a factor of two. Since the analysis is believed to be the most crucial part, the provision of multiple analysis positions will be useful to meet an overall throughput rate.
  • An effective analysis time can be reduced by a factor of two. Since the analysis is believed to be the most crucial part, the provision of multiple analysis positions will be useful to meet an overall throughput rate.
  • anyone skilled in the art realizes that also more than two analysis positions 40 can be provided, thereby reducing the effective analysis time even further.
  • the log support structures with all its parts, and e.g. the transducers and transducer support structures have to be provided in multiples.
  • the dimension determination arrangement, the acoustic measurement equipment 60 and the means for classification 70 can be common resources for both analysis positions 40. In such a way, the provision of double analysis positions will result in limited increased costs compared to a single analysis position configuration.
  • Fig. 9 illustrates yet another embodiment of an arrangement for classifying logs 1.
  • the log is transported through the dimension determining arrangement 16 onto cradle 130 of conveyor rolls 132.
  • a follower wheel 17 of the dimension determining arrangement 16 is integrated in a last part of the input conveyor 12.
  • the entire cradle 130 is tiltable by means of tiltable supports 131 into an analysis position 40.
  • Weighing devices 34 are integrated in the tiltable supports 131.
  • Fig. 9 illustrates the situation where the cradle is in the analysis position.
  • a movable measuring carrier 28 and a stationary measuring carrier 26 are provided hanging down from a beam 134.
  • the movable measuring carrier 28 is arranged to be movable along the beam to obtain a coarse position.
  • An advantage of such a configuration is that the rotation of the log 2 is fairly well controlled and angular differences in the dimension determination can easily be utilized for analysis purposes.
  • a disadvantage is that the ends of the log 2 have to stick out from the cradle 130 in order to allow the movable measuring carrier 28 to move without collision risks with the cradle 130. This in turn limits the length variations of the logs that can be accepted by the arrangement.
  • the log 2 has to leave the cradle 130 and the cradle has to be tilted back into a position in front of the dimension determination arrangement 16 before the next log 2 can pass the dimension determination arrangement 16.
  • Fig. 1OA also illustrates an embodiment of an arrangement 1 for classifying logs, here utilizing a transverse transport to and from an analysis position 40.
  • Logs 2 are provided to the introduction part in any conventional manner.
  • the logs 2 are picked out from a pile of logs by a transporting staircase 136 and the transporting staircase 136 together with transport chains 146 convey the logs 8 into the analysis part 20 in a transverse manner up onto a measurement table 135.
  • a length of the log 2 is measured by a dimension determining arrangement 16, in this embodiment two laser distance meters 140, provided at each ends of the log 2.
  • the length information is as above utilized for an active controlled coarse positioning of transducers 50 in the axial direction 3, described more in detail below.
  • the analysis part 20 comprises totally four analysis positions 40 at the measurement table 135, which means that four logs 2 can be analyzed at a time.
  • an Y frame 142 moves up and grips the log 2 from below.
  • the Y frames 142 move with the transport chains 146 and continue the transverse transport of the logs 2. This is illustrated in Fig. 1OA, where the different logs 2 at the measurement table 135 have significantly different lengths and axial positions.
  • driving rollers 144 are provided at the Y frames 142, which driving rollers 144 are driven to displace the log 2 in the axial direction 3 towards a stop plate 14.
  • Fig. 1OB is a top view of the situation after such an alignment.
  • movable measurement carriers 28, on which transducers 50 and in this embodiment also a camera 138 are mounted are coarse positioned in the vicinity of a respective end of the logs 2, opposite to the aligned ends.
  • the stop plate 14 is moved down so that all the four log ends are free from being covered by any objects.
  • Stationary measurement carriers 26, stationary in the axial direction 3, are moved down to their respective measurement positions.
  • the stationary measurement carriers 26 are in this embodiment also equipped with transducers 50 as well as cameras 138.
  • the stationary measurement carriers 26 and movable measurement carriers 28 are in this embodiment similar to the ones illustrated in Fig. 6.
  • the cameras 138 are positioned to aim at the respective log end.
  • the cameras are preferably using a preset focus, since the distance to the log ends are fixed within certain uncertainty intervals.
  • the cameras 138 registers pictures of all the log ends, which can be used as additional information during the log classification stage as well as for determine the boundary of the log end, for the fine radial positioning of the transducers 50.
  • This functionality can easily be provided in an embedded image processing computer in each camera.
  • the cameras 138 may be provided at carriers separate from the measurement carriers 26 and 28. These carriers may both be stationary in the axial direction 3. In such a case, the cameras provided at the aligned log ends can operate with a fixed focus, while the cameras provided for registering the non-aligned ends have to be provided with auto- focus functionalities.
  • the boundary information obtained from the cameras are preferably used to adjust the radial positions of the transducers 50 at both the stationary measurement carriers 26 and the movable measurement carriers 28. Thereafter, the transducers 50 are fine adjusted in the axial direction 3 into the required measurement positions. In case the transducers 50 operate with measurements or excitations requiring mechanical contact, the transducers are gently moved in contact with the log ends. In case the transducers 50 operate with contact-free measurements or excitations, the transducers are moved into the proper positions at a prerequested distance from the log ends. Acoustic measurements are then performed. After the acoustic measurements, the movable measurement carriers 28 are removed from the log ends in order to allow removal of the logs from the measurement table 135. In the present embodiment, the logs 2 are moved into a discharge transport conveyor 148, which transports the logs away from the arrangement 1 for classifying logs.
  • the outer shape can e.g. be analyzed in order to identify occurrence of pressure deformed wood and the pattern and dimensions of the annual rings can give information about expected density of twigs and branches.
  • Such information can be combined with the results of the acoustical measurements for achieving an even more reliable quality classification, c.f. the property measurements 71 in Fig. 2.
  • Such information deduced from the pictures can be extracted from one of the log ends or from both, depending on the allowed complexity and cost of analysis.
  • analysis and control electronics are omitted.
  • anyone skilled in the art realizes that e.g. different kinds of electronic circuitry for position control, classifying, acoustical measurement control, and camera control has to be provided.
  • the Y frames 142 may lack driving rollers 144. In such an embodiment, the Y frames 142 just lift the logs from the measurement table 135 to fix them in position. Instead, movable measurement carriers 28 are provided at both ends of the log 2. The coarse positioning there preferably involves coarse positioning of the movable measurement carriers 28 on both ends of the log 2. Since the actual longitudinal position of the log on the measurement table 135 may shift somewhat during the transverse transport, a coarse positioning in longitudinal direction has preferably to be performed with sufficient security margins, and a fine positioning can be further supported by camera picture analysis and/ or laser distance measurements at each analysis position.
  • FIG. 1 1 illustrates a block diagram over such an arrangement.
  • a saw mill production line 150 comprises a log classification section 152 having an arrangement for log classification 152 according to the above described principles.
  • Logs pass through the log classification section 152, have their dimensions measured by a dimension determining arrangement 16 and can thus easily be associated with the corresponding diameter data 160.
  • the logs When exiting the log classification section 152, the logs are transported into a diameter sorting section 154.
  • an additional diameter measuring equipment 156 measures the diameter of the incoming logs.
  • the control unit 164 assigns a diameter class to each log.
  • the logs When the logs are output into a diameter sorting arrangement 166, the logs are directed into different bins 158 depending on the diameter class.
  • independent diameter measurements are available and there is thus an opportunity to find discrepancies between the two independent diameter determinations.
  • a part of such discrepancies can be explained by systematic measurement differences and may easily be calibrated by statistical methods. If such calibrated diameter measures anyway differ between the two measurements more than a predetermined threshold, one may assume that at least one of the measurements have to be erroneous.
  • the log can then be assigned to be separated into a remeasuring line 162 and be transported back to the log classification section 152 instead of being separated into a bin 158 of a particular diameter range.
  • Such simple arrangement is believed to be capable of increasing the probability of correct sorting, possibly up to a degree of 99%. The cost reduction for correcting mis- sorted logs will be enormous.
  • the diameter data 160 can be accompanied by data associated with the classification of the log, performed in the log classification section 152.
  • the control unit 164 can then be arranged to assign a classification, not only based on log diameter, but also on various property classification. This makes it possible e.g. to separate logs being classified as low quality logs into particular bins, irrespective of the diameter, while logs of "normal" quality still is sorted by diameter. Also exceptionally high-quality logs may be separated out in particular bins.
  • One alternative to the remeasuring line 162 would be to provide the control unit 164 with a discrepancy analysis section, provided with software for evaluating situations where the dimension measures differ, and provide a best estimate of a probable diameter, which then is used for sorting purposes.
  • a laser scanner equipment is used as an example of a dimension determination arrangement, where a follower wheel is responsible for the actual length measurement.
  • a follower wheel is responsible for the actual length measurement.
  • other length measuring devices and arrangements can be used.
  • a light emitter and optical sensor arranged at opposite sides of the log path will easily detect the beginning and end of a log. Together with speed information from the conveyor equipment, a log length can easily be determined.
  • dimension determination arrangements based on e.g. other type of radiation can equally well be utilized.
  • pure mechanical solutions can be found, e.g., where a number of follower wheels are provided around the periphery of the log to determine diameter as well as length.
  • different kinds of transducers can be provided.
  • the number of transducers on each side of the log also depends on the actual analysis that is going to be performed. In order to enable analysis according to the principles presented in WO2007/011296, at least two transducers are provided at each side. As can see in the embodiments described above, more transducers are also possible.
  • the classification marking is performed when the log still remains in the analysis position. In order to shorten the time in the analysis position even further, such marking can be made in a later stage. In such a configuration, the identities of the logs have to be possible to recover, which easily is provided by maintaining the order of the logs in which they were analyzed.
  • the acoustic measurement equipment, the means for classifying, the control unit of the position control and the dimension determination arrangement are described as separate units.
  • at least parts of these items are advantageously implemented by different processors and functionality of two or more of the items may therefore advantageously be combined in one and the same processor.
  • the separate units illustrated in the figures above should therefore be considered as functionality units rather than physical unit. However, different physical units are of course also possible to use.

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Abstract

L'invention porte sur un agencement de classification de grumes (1), qui comporte un moyen de transport (21) destiné à amener une grume (2) dans une structure de support de grume (24) dans une position d'analyse (40). Des transducteurs (50) pour des mesures acoustiques peuvent être positionnés dans des positions de mesure aux extrémités de la grume (2). Un agencement de circuit électronique (60) d'un équipement de mesure acoustique et un moyen de classification (70) de grumes sont connectés aux transducteurs (50). L'agencement comporte en outre un agencement de détermination de dimensions (16) agencé pour déterminer les dimensions externes de la grume avant que la grume ne soit amenée dans la position d'analyse. L'agencement comporte également une commande de position (55) destinée à commander une position approximative dans la direction axiale de structures de support de transducteurs connectés sur la base des dimensions externes déterminées. La commande de position est en outre agencée pour assurer la commande au moins partiellement avant ou au moins partiellement simultanément à l'amenée de la grume dans la position d'analyse. L'invention porte également sur un procédé correspondant.
PCT/SE2008/051389 2007-12-07 2008-12-02 Procédé et agencement de classification de grumes WO2009072968A1 (fr)

Applications Claiming Priority (2)

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SE0702752 2007-12-07
SE0702752-7 2007-12-07

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WO2009072968A1 true WO2009072968A1 (fr) 2009-06-11

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101710576B1 (ko) * 2015-08-26 2017-03-08 주식회사 에코란티 바형 레일이 구비된 초음파 탐상장치
CN108325869A (zh) * 2018-02-07 2018-07-27 国家林业局北京林业机械研究所 一种锯材分等装置及方法
CN108972806A (zh) * 2018-08-24 2018-12-11 王步熬 分料装置
CN109013376A (zh) * 2018-10-24 2018-12-18 福建农林大学 一种原木自动分级分拣装备结构
CN109443175A (zh) * 2018-11-30 2019-03-08 南安市晨星机械科技有限公司 建筑检测用的圆木尺寸检测装置
CN109530253A (zh) * 2018-11-02 2019-03-29 陈伟贞 一种半成品木材分拣控制系统

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3736968A (en) * 1970-11-25 1973-06-05 Sun Studs Method and apparatus for processing logs
US4515196A (en) * 1983-01-28 1985-05-07 Shields Dean W Log handling and sawing system
US5097881A (en) * 1991-04-25 1992-03-24 Blount, Inc. Ultrasonic log grading
WO2002008749A1 (fr) * 2000-07-21 2002-01-31 Industrial Research Limited Procede et appareil d'evaluation ou prevision les caracteristiques de bois ou autres materiaux ligneux
WO2003093800A1 (fr) * 2002-05-02 2003-11-13 CENTRE DE RECHERCHE INDUSTRIELLE DU QUéBEC Appareil et procede de test de la rigidite d'articles
WO2007011296A1 (fr) * 2005-07-15 2007-01-25 A-Sort Ab Dispositif et procédé de classement de billes de bois

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3736968A (en) * 1970-11-25 1973-06-05 Sun Studs Method and apparatus for processing logs
US4515196A (en) * 1983-01-28 1985-05-07 Shields Dean W Log handling and sawing system
US5097881A (en) * 1991-04-25 1992-03-24 Blount, Inc. Ultrasonic log grading
WO2002008749A1 (fr) * 2000-07-21 2002-01-31 Industrial Research Limited Procede et appareil d'evaluation ou prevision les caracteristiques de bois ou autres materiaux ligneux
WO2003093800A1 (fr) * 2002-05-02 2003-11-13 CENTRE DE RECHERCHE INDUSTRIELLE DU QUéBEC Appareil et procede de test de la rigidite d'articles
WO2007011296A1 (fr) * 2005-07-15 2007-01-25 A-Sort Ab Dispositif et procédé de classement de billes de bois

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101710576B1 (ko) * 2015-08-26 2017-03-08 주식회사 에코란티 바형 레일이 구비된 초음파 탐상장치
CN108325869A (zh) * 2018-02-07 2018-07-27 国家林业局北京林业机械研究所 一种锯材分等装置及方法
CN108325869B (zh) * 2018-02-07 2023-05-05 国家林业局北京林业机械研究所 一种锯材分等装置及方法
CN108972806A (zh) * 2018-08-24 2018-12-11 王步熬 分料装置
CN109013376A (zh) * 2018-10-24 2018-12-18 福建农林大学 一种原木自动分级分拣装备结构
CN109530253A (zh) * 2018-11-02 2019-03-29 陈伟贞 一种半成品木材分拣控制系统
CN109443175A (zh) * 2018-11-30 2019-03-08 南安市晨星机械科技有限公司 建筑检测用的圆木尺寸检测装置
CN109443175B (zh) * 2018-11-30 2021-04-23 安徽省瀚辰生态建设有限公司 建筑检测用的圆木尺寸检测装置

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