AU780469B2 - Unfinished wood product cutting optimization system - Google Patents

Description

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: Name of Applicant: Weyerhaeuser Company Actual Inventor(s): WILLIAM D SNYDER, ELMER CHRISTENSEN, STANLEY L FLOYD, LARRY H JONES, CALVIN K KENDALL, BILLY B PEARCE, EVERETTE SHAW, MICHAEL J YANCEY Address for Service: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: UNFINISHED WOOD PRODUCT CUTTING OPTIMIZATION SYSTEM Our Ref: 622785 POF Code: 19671/19671 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): 22,154a UNFINISHED WOOD PRODUCT CUTTING OPTIMIZATION SYSTEM Field of the Invention The present invention relates to wood product processing systems in general, and systems for optimizing lumber cutting decisions in particular.

Background of the Invention In any manufacturing business, profitability depends in part on the extent to which the conversion of raw materials into finished products is optimized. This is particularly true in the wood products industry where raw logs are cut into lumber.

Currently, the decision of how to cut lumber from a log is made by having a human operator visually grade a log based on such features as the number of knots in the log, the straightness of the log, any rot, etc. Next, the log is scanned using lasers or other sensors to determine its shape and dimensions. Given the grade of a log, a price table is selected and used by the sawing system's optimizing computer to calculate the assortment of lumber sizes that maximizes the value recovered from the log. The price "tables are based on lumber market values, historical sawmill recovery data and may also take into account market demand by grade and dimension.

While this method works well for sawmills selling only visually graded lumber, it does not work well for mills wanting to sell various grades of higher-valued stress-rated lumber. For instance, it is well known that for some dimensions, lumber having a high modulus of elasticity (MOE) or stiffness is worth more than lumber with a low MOE. Boards having a high MOE and appropriate strength properties can be 25 used in such applications as floor joists or roof trusses where such properties are desired. However, the relation between stiffness and price is not always straightforward.

For example, 2" x 8" (50.8 X 203.2 mm) boards are very desirable if they meet certain stiffness and strength criteria, but not very desirable if they do not. Having an advance estimate of the structural properties of the wood allows the sawing optimization system to avoid making low stiffness/strength 2x8 lumber, and instead making either 2x6 (50.8 X 152.4 nun) or 2x10 (50.8 X 254 mm) lumber where the price penalties for lower structural properties are less pronounced. In the past, there has not been a practical way to predict the MOE of lumber to be produced from a log and to take the predicted MOE into consideration when making cutting decisions.

Given the shortcomings in the art, there is a need for a system that can determine and consider the potential stiffness of lumber to be cut from a log in addition to the conventional measurements of shape and dimensions in order to make a cutting decision that will maximize the profit to be made from an individual log.

4.FEB.2005 15:21 4.FEB2085 5:21 P-ILLIPS ORM FIrZ 61299294511 N.2 .42 NO.524 P.14/24 2 Summary of the Invention The present invention is a stress wave velocity system that estimates the stiffness of lumber to be produced fiom unfinished wood products such as logs, eants, or boards. To use logs as an example, an accelerometer is placed agaiust the log while the log is struck with a pneumatic hammer. Signals received from the accelerometer are analysed to estimate the speed of a stress wave induced in a log. Once the speed of the stress wave is known, a price table is selected that relates various lumber dimensions to current market prices. A computer system within the sawmniUl utilizes the selected price table to maximize the value of the lumber produced from a given log.

The stress wave velocity system includes a pair of proximity sensors that determine whether a log is present. If a log is present, a sensor tube including the accelerometer and pneumnatic hammer is moved on a sliding carriage to engage the log.

Air stored in a pneumatic accumulator is released into the hammer such that a striking face of the hammer engages the log. Vibration signals from the accelerometer are digitized, and transfonmed to the frequency domain by a computer-based signal analys er. The computer based signal analyser searches the signal spectrum for resonance frequencies caused by the pneumatic hammer. Estimates of a length of a log redetermined from a laser on one end of the log and by measuring the distance that the 0O sensor tube is moved in order to engage the log at the other end. From the length of the log and the resonance frequency determined, the speed of the stress wave in the log can be estimated. From the speed of the stres wave, an appropriate price table is selected and used by the computer system to determine the optimium manner in which to out r. lumber from the log.

According to one aspect the present invention provides a method of predicting one or more structural properties of lumber to be cut from gn unfinished wood product and to use the one or more predicted structural properties in determining how the unfnished wood product can be cut by a lumber breakdown system, comprising: grading an exterior of the unfinished wood product; determining a first plurality of price tables for which lumber may be recovered from the unfinished wood product based onl the grading of the exterior of the unfinished wood product; measuring a length of the unfinished wood product; generating a stress wave in the unfinished wood product; COMS ID No:SBMI-01 108840 Received by IP Australia: Time 15:20 Date 2005-02-04 4.FEB.2005 15:21 4.FEH2005 5:21 PHILLIPS ORMi FITZ 61299294511 N.2 .52 NO.524 P.15/24 2a determining a stress wave velocity in the unfinished wood product, the stress wave velocity being related to a modulus of elasticity of the lumber to be ou$ from the unfinished wood product; selecting a lumber price table from the first plurality of price tables based on the determined stress wave velocity, the price table relating lumber dimensions having the predicted modulus of elasticity to a current market value; and providing the selected price table to the lumber breakdown system that determines a set of dimensions of the unfinished wood product and computes how the unfinished wood product should be cut to maximize the value of the lumber recovered from the unfinished wood product.

According to another aspect, the present invention provides a system for predicting a modulus of elasticity of lumber to be cut from. a unfinished wood product and to use the predicted modulus of elasticity in determining how the unfinished wood product cani be cut by and optimized by a unfinished wood product breadown system, comprising: grading an exterior of the unfinished wood product; :determining a first plurality of price tables for which lumber may be recovered from the unfinished wood product based on the grading of the exterior of the 20 unfinished wood product; a measurement system that determines a length of the unfinished wood product; a hammer that selectively strikes the unfinished wood product to impart a. stress wave in the unfinished wood product; 25a sensor that measures vibrations in the unfinished wood product from the stress Wave; a computer system that receives signals from the sensor and determines a velocity of the stress wave that is related to the modulus of elasticity of the lumber to be *cut from the unfinished wood product, the computer system selecting a lumber price table from the first plurality of price tables based on the predicted modulus of elasticity, wherein the lumber price table relates lumber dimensions having the predicted modulus of elasticity to a current market value, the computer system further providing the selected lumber price table to the lumber breakdown system to determine how the unfinished wood prodqcet should be cut to maximize the value of the lumber recovered from the unfinished wood product.

COMS ID No: SBMI-0110640 Received by IP Australia: Time 15:20 Date 2005-02-04 4.FEB.2005 15:21 4.FEB2005 5:21 PHILLIPS ORM FITZ 61299294511 N.2 .62 NO.524 P.16/24 2b According to a further aspect, the present invention provides a method of processing boards from a primary breakdown system in a sawmill comprising: grading an exterior of the board; s determining a first plurality of price tables for which lumber may be recovered from the board based on the grading of the exterior of the board; measuring a length of the board; generating a Mtess wave in the board; determining a stress wave velocity in the board, the stress wave velocity being related to a modulus of elasticity of the board; selecting a price table from the first plurality of price tables based on the predicted modulus of elasticity; the price table relating wood products having the predicted modulus of elasticity to a current market value; anad processing the board in accordance with the selected price table such that a value of the wood products produced from the board is maximized.

According to yet aohraspect, the present invention provides a method of processing unfinished lumber on a trimmer system in a sawmill comprising: .2:..:grading an exterior of the unfinished lumber; determining a first plurality of price tables far which lumber may be recovered ~from the unlfinished lumber based on the grading of the exterior of the unfinished lumber; .measuring a length of a piece of unfinished lumaber; generatig a stress wave in the unfinished lumber; :determninffg a stress wave velocity in the unfinished lumber, the stress wave velocity being related to a predicted modulus of elasticity of the unfinished lumber; selecting a price table fromt the first plurality of price tables based on the predicted modulus of elasticity; the price table relating wood products having the predicted modulus of elasticity to a current market value; and processing the unfinished lumber with the trimmner system in accordance with the selected price table such that a value of the wood products produced from the unfinished lumber is maximized, COMS ID No: S8MI-01106640 Received by IP Australia: Time 15:20 Date 2005-02-04 4.FEB.2085 15:22 PHILLIPS CR11 FITZ 61299294511 NO.524 P.17/24 2c According to yet a fljther aspect, the present invention provides a method of processing unfinished wood products on a mre stem merchandiser in a sawmill comprising: grading an exterior of the unfinished wood product; determining a first plurality of price tables for which lumber may be recovered from the unfinished wood product based on the grading of the exterior of the unfinished wood product; measuring a length of the unfinished wood product; generating a stress wave in the unfinished wood product; determining a stress wave velocity in the unfinised wood product, the stress wave velocity being related to a modulus of elasticity of the tree stem; selecting a price table from the first plurality of price tables based on a predicted modulus of elasticity, the price table relating wood products having the predicted is modulus of elasticity to a current market value; and *processing the unfinished wood poutsuch thta value of the wood products~ produced from the unfinished wood product is maximized.

:Brief Description of the Drawings The foregoing aspects and many of the attendant advantages of this invention 20 will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when takcen in conjunction with the accompanying drawings, wherein: :FIG,' I is a block diagram of a stress wave velocity (SWVV) system that obtains prs which are used to determine how logs are to be out into lumber according to the prsentinvention; FIG. 2 is an environmental view of a stress wave signal acquisition unit (SAU) tha obtains stress wave signals from a log according to the present invention; FIG. 3 is a front isometric view of the SAUl according to the present invention; FIG. 4 is a rear isometric view of the SAUl according to the present invention; COMS ID No: SBMI-01 106640 Received by IP Australia: Time (t1:m) 15:20 Date 2005-02-04 FIG. 5 is a side elevation view illustrating how the SAU engages a log; FIG. 6 is a plan view showing in detail how an accelerometer and pneumatic hammer of the SAU engage a log; FIG. 7 is a chart, illustrating the relationship between the speed of the stress wave in the log and the MOE of the wood in the log.

Detailed Description of the Preferred Embodiment The present invention is a system for predicting the modulus of elasticity (MOE) or stiffness and associated structural properties of lumber to be cut from a log. By knowing the MOE of the wood in the log, more optimal decisions can be made regarding how a log is to be processed.

FIG. 1 is a block diagram of a portion of a sawmill where raw logs are received and cut into lumber. A number of logs 50 are moved towards a series of cutting saws (not shown) by a log ladder 52. At the top of the log ladder, the movement of a log is suspended for approximately two seconds while an operator of the log ladder visually 15 grades the log. The log is then rolled onto a "sharp chain" 54 a primary breakdown infeed system) that carries the log to the cutting saws.

To supplement the information used to make cutting decisions, the present invention is a stress wave velocity (SWV) system that determines the speed of a stress wave that is induced in a log. The SWV system includes a stress wave signal acquisition unit (SAU) 22 that engages the log 50 while it is halted on the log ladder and imparts a stress wave into the log. The distance that the SAU 22 is moved to engage the log is measured. In addition, a laser 24 is used to measure the distance to another end of S °the log. From these measurements, the length of the log is determined.

As will be described in further detail below, the SAU 22 strikes the log with a °oot.i S 25 pneumatic hammer and picks up vibrational signals from a standing stress wave in the log with an accelerometer. From the round-trip time of the stress wave, the speed of the .i stress wave in the log can be estimated and correlated to a predicted MOE of the lumber to be produced from the log.

The SWV system further includes a SWV analysing computer system 26 that receives the electronic signals produced by the accelerometer within the SAU 22.

Finally, the SWV system includes a pair of basic modules 28 and 30 that provide data from the SWV analysing computer system 26 and the laser 24 to a programmable logic controller 32. The programmable logic controller 32 controls the operation of the log 4 ladder 52, the sharp chain 54 and the cutting saws (not shown). The controller 32 is interfaced with a computer system 34 that is part of the primary breakdown system of the sawmill that receives data from a plurality of conventional sensors (not shown) that determine the dimensions of the log including its length, diameter and taper. From these measurements, the computer system 34 determines the lumber that should cut from the log.

To determine the speed of a stress wave in the log 50, the programmable logic controller 32 directs the SAU 22 to move toward the log 50. The distance that the SAU has to extend in order to engage the log is recorded. The distance together with the measurements made by the laser 24, allows the programmable logic controller 32 to compute the length of the log. Once the SAU has engaged the log, the programmable logic controller 32 causes the SAU 22 to impart a stress wave in the log. The vibrations caused by the stress wave are detected by the SAU and provided to the SWV analysing computer system 26.

Because the SAU 22 is subject to a great deal of vibration that is produced from the machinery and logs moving within the sawmill, the SWV analysing computer system 26 analyzes the signals received from the accelerometer within the SAU 22 in order to separate those signals caused by the stress wave from those induced by the .•""background noise. To accomplish this, the SWV analysing computer system 26 20 digitizes the signals received from the accelerometer. The signals are then transformed into the frequency domain using a conventional Fast Fourier Transform. Next, the SWV analysing computer system 26 searches for resonance frequencies in the spectrum between a lowest and a maximum expected frequency.

The speed of the stress wave induced by the SAU 22 can be measured by 25 determining the time it takes the stress wave to travel to the end of the log and back according to the equation: S= 2L 000$0 where S is the speed of the stress wave, L is the length of the log and is the round trip time. In the frequency domain, the time for the stress wave to travel to the end of the log and back is related to the resonance frequency of the stress wave according the equation: "f where fis the resonance frequency of the stress wave. Therefore the speed of the stress wave, S, can be determined according to the equation: S=2Lf (3) In practice, it is known that the speed of the stress wave varies between an expected minimum of approximately 6000 feet per second to a maximum of approximately 20,000 feet per second. Therefore the spectrum of the signals produced by the accelerometer is searched for resonance frequencies that occur between a lowest expected frequency (LEF) and a maximum expected frequency (MEF) that are defined by the equations: LEF Smin 2L (4) MEF Sma x /2L Once the resonant frequency is found, it is used in Equation 3 to compute the speed of the stress wave inducted in the log by the pneumatic hammer.

From the speed of the stress wave in the log, an estimate of the modulus of elasticity or MOE of the log can be made. According to the chart set forth in FIG. 7, it has been determined that the speed of the stress wave in the log varies directly with the MOE of the wood in the log. This data was obtained for Loblolly pine. As will be appreciated by those skilled in the art, the particular relationship between the speed of the stress wave and the MOE of the wood in a log may vary depending on the type of wood being analysed, the age of the log or other factors. The particular relationship for other types of wood is determined by measuring the SWV in a log, cutting lumber from the log and following the lumber through the manufacturing process. The MOE of the lumber is then carefully measured in a laboratory and related to the SWV measured.

Once speed of the stress wave in the log has been determined, a price table for the log is selected. Table 1 illustrates the currently preferred method of selecting price tables. Stress wave velocities below 11,000 feet per second are considered to correlate to relatively low MOE'S, while stress wave velocities above 12,000 feet per second correlate to a high MOE.

TABLE 1: PRICE TABLE SELECTION CRITERIA Log Grade Input SWV Thresholds Log Position 1 2 3 SWV=<11000 All Table 1 Table 2 Table 3 11000<SWV<12000 First Table 4 Table 4 SWV>=12000 First Table 5 Table 6 11000<SWV<12000 Second Table 7 Table 7 SWV>=12000 Second Table 8 Table 8 As in the past, the operator of the log ladder indicates whether the log is either grade I, II or III. In addition, the operator of the log ladder indicates whether the log is from the base of a tree (the first log position) or from higher up (the second log position). This information is used to select the preferred price table. For example, a grade I log from a first position having a stress wave velocity between 11,000 and 12,000 feet per second uses price table 4. A similar log having a stress wave velocity that is greater than 12,000 feet per second uses price table 5 etc. Because the higher 10 stress wave velocity is indicative of wood having a higher MOE, price table 5 can be constructed to reflect the premium that can be charged for the stiffer boards produced.

Once the appropriate price table is selected, the computer system 34 of the primary breakdown system uses the selected price table as well as the measurements of the log's dimensions to determine the most optimum series of cuts to make to maximize the value of the lumber produced.

FIG. 2 illustrates the SAU 22 in greater detail. In order to shield the stress wave SAU 22 from as much vibration as possible, the SAU is mounted on a pedestal 58 that .o* is not coupled to the log ladder 52. The SAU 22 preferably obtains its signals from a ooo# log at the position on the log ladder where the log is halted momentarily in order to 0oo0i 20 grade the log prior to being placed on the sharp chain 54. Although the SAU 22 could be located at other positions along the log ladder 52, obtaining the stress wave velocity just before the logs are placed on the sharp chain is preferable because logs will sometimes get out of order as they travel on the log ladder. If this happens, it can be difficult to associate the SWV data received with a particular log to be cut. The SAU 22 illustrated in FIG. 2 is shown without a protective cover. However, in practice a metal cover having an open end for a pneumatic hammer and an accelerometer is placed over the device to protect the components therein and to reduce the amount of dirt that enters the device.

As shown in FIG. 3 the SAU 22 is built on a U-shaped aluminum base channel 62 having a substantially flat bottom surface and short side walls. Disposed at equal distances along the length of the base channel are three U-shaped stiffening members 64. The stiffening members 64 have a flat base portion that is seated on the bottom surface of the base channel and a pair of arms that engage an inner surface of the side walls such that the side walls are strengthened.

To increase the height of the SAU 22, the base channel 62 is secured to a foot channel 66 that is a piece of U-shaped aluminum having the same width as the base channel. The length of the foot channel 66 is shorter than the length of the base channel 62 such that when the base channel 62 and the foot channel 66 are aligned at one end, the base channel overhangs a portion of the foot channel.

Secured to the flat portion of the stiffening members 64 is a sliding carriage 68. The sliding carriage includes a base plate 70 that is moved by a pneumatic 20 piston back and forth along a pair of rods 72. The sliding carriage 68 is preferably equipped with rod wipers and pressurized bushings to reduce the amount of saw dust and grit that gets between the base plate 70 and the rods 72. The sliding carriage used in the presently preferred embodiment of the invention is a PHD Slide Model x 8 available from PHD, Inc. of Fort Wayne, IN.

Mounted to the base plate 70 of the sliding carriage 68 is a sensor tube 76. The sensor tube 76 houses an accelerometer 78 and a pneumatic hammer 84.

The accelerometer 78 has a metal tip 80 that engages a cut surface on a log in order to °measure vibrations caused by a stress wave within the log. The accelerometer is mounted to the sensor tube 76 with a rubber gasket 82 that shields the accelerometer from vibrations caused by the SAU 22 as well as from some of the vibrations occurring in the sawmill.

Positioned behind and on either side of the sensor tube 76 are a pair of photoelectric proximity sensors 90 that determine when a log is present in front of the SAU 22. The sensors 90 are supported by a pair of vertically extending arms 92 having one end secured to the bottom surface of the base channel 62. The arms are connected with a linkage 93 so as to form an arch behind the sensor tube 76.

When the presence of a log is detected by the photoelectric sensors the sensor tube 76 on the base plate 70 is moved until the metal tip 80 of the accelerometer 78 engages the cut surface of the log. The pneumatic hammer 84 is then fired in order to impart a stress wave into the log. The accelerometer measures the longitudinal vibrations of the log in order to estimate the speed of the stress wave, which is related to the MOE or the stiffness of the wood in the log.

Also included in the base channel 62 is an inductive proximity sensor 94 that detects the presence of a metal plate 96 that extends outwardly from the base 70 of the sliding carriage 68. The proximity sensor is used to tell when the sensor tube 76 is in the fully retracted position and therefore when the log ladder can be restarted.

Finally, the foot channel 66 includes a number of pneumatic hose connectors 98 to which pneumatic hoses are inserted in order to supply the unit SAU 22 with compressed air to drive the sliding carriage 68 and fire the pneumatic hammer 84.

FIG. 4 shows the SAU 22 with one of the side walls of the base channel 62 removed to further illustrate the components contained therein. The foot channel 66 is secured to a bottom surface of the base channel 62 with a pair of angle brackets 100.

Disposed behind the photoelectric proximity sensors 90 is another photoelectric distance sensor 110. The distance sensor 110 is mounted on a generally L-shaped bracket 112 that is secured to the bottom of the base channel 62. Light from the distance sensor 110 shines through the arch created by the arms 92 and linkage 93 that support the proximity sensors 90. The light measures the distance to a white reflecting plate 114 that is mounted to an end of the pneumatic hammer 84.

A pressure regulator 120 receives compressed air from a pneumatic hose 122 that is connected to a hose connector 98. The pressure regulator 120 provides compressed air to the pressurized bushings of the sliding carriage.

FIG. 5 illustrates how the sensor tube 76 is extended on the base 70 of the slidable carriage 68 in order for the accelerometer to engage a cut surface at an end of a log 50. When the log 50 reaches the top of the log ladder, the base 70 of the sliding carriage is extended until the metal tip 80 of the accelerometer contacts the log.

°The metal tip 80 continues to be forced against the log until the pneumatic hammer is fired and the signals produced by the accelerometer have been recorded. After the signals from the accelerometer have been recorded by the SWV analyzing computer system 26 (FIG. I1), the base 70 and sensor tube 76 are retracted until the next log is ready to be measured.

The details of the sensor tube 76 and pneumatic hammer 84 are shown in FIG. 6. As discussed above, the accelerometer 78 is mounted to a front face of the sensor tube 76 with a rubber gasket 82. The accelerometer 78 is preferably a PCB Model #328F11 I available from PCB Piezotronics, Inc. of Depew, New York. However other accelerometers could be used. Signals from the accelerometer are carried on a cable 140 to the remotely located SWV analyzing computer system where the signals are analyzed in order to compute the speed of stress wave in the log.

8 The pneumatic hammer 84 comprises a cylindrical tube 144 having a cap 146 disposed at an end thereof. The reflective plate 114 is secured to the outer face of the cap 146. At the other end of the cylindrical tube 144 is a second cylindrical tube 148. The cylindrical tube 148 includes a butt section 150 that is undercut to fit within the tube 144 and form a friction fit. The butt section 150 is sealed at one end and receives compressed air from a pneumatic hose 152 that is connected to the pneumatic accumulator 131 (shown in FIG. Within the second cylindrical tube 148 is a movable cylinder 156 having a hammer striking surface 160 at its distal end. When air stored in the pneumatic accumulator 131 is released by a solenoid valve 130 (FIG. 4), the air is carried by the hose 152 to the butt section 150 of the hammer. The air is then expelled from an open end of the cylindrical tube 148 thereby carrying the movable cylinder 156 forward to strike the cut surface of the log. After striking the log, the movable cylinder 156 is retrieved within the cylindrical tube 148 by a spring 164 that has one end fixed to the cap 146 at the end of the hammer.

As can be seen, the present invention provides additional information concerning how logs can be cut to maximize their economic value. By determining the velocity of a stress wave in the log, estimations can be made of the stiffness of the lumber that will be produced. This stiffness value can be factored into the determination of how the log will be cut in order to produce maximum value. Because an estimation of 20 the MOE of the wood can be determined before the log is cut, a better use of the wood in the log can be made.

While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention. For example, the present invention can be used on a stem merchandiser to aid in deciding which logs should be used to make lumber or other products such as plywood etc. Stems with high SWV's could be cut into sawmill logs to produce high stiffness/strength lumber once it is determined "that a stem has a high enough SWV to produce lumber, the stem can be cut into lengths that will optimize the value of the lumber produced. Stems with lower SWV's could be cut into logs for plywood where high stiffness and strength properties are not required.

Another use of the present invention is in an edger breakdown optimization system. A sawmill primary breakdown system breaks logs into cants and sideboards, using saws and chipping devices. Cants are routed to a cant edger (also known as a gang edger), which breaks the cants down into boards, using saws and chipping devices.

It is typical that some of the cant boards do not have the full cross section for the target lumber over the entire length, but contain areas where part of the original, rounded surface of the log are still present. Such boards are routed to a board edger, which will reduce the width and/or the thickness of the board such that a piece 9 of lumber of optimal value is produced. The cant boards may be routed to a trimmer on their way to the edger. The trimmer typically has a scanner and an optimisation system which decides whether to just trim off the part of the board which does not have the required cross section, or decides to pass the entire piece on to the edger. After edging, the pieces are then routed back through the trimmer, where the boards are cut into their optimal lengths.

Sideboards may have two or four machined surfaces, defining the target thickness and/or width of the boards, but they typically contain large areas of the original rounded surface of the log. Sideboards are treated the same way as the cant boards needing trimming and/or edging.

As in the case of the primary breakdown application of the invention, a more valuable assortment of lumber can be obtained if knowledge of the modulus of elasticity of the lumber were known and used by the trimmer and edger breakdown optimization systems.

Throughout the description and claims of this specification, the word "comprise" and variations of that word, such as "comprising" and "comprises" are not intended to exclude other additives, steps or integers.

S o *o

Claims (15)

1. 4.FEB.2005' 15:22 PHILLIPS ORM FITZ 61299294511 M0.524 P.18/24 THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A method of predicting one or more struotural properties of lumber to be cut from an tWninished wood product and to use the one or more predicted structural properties in determinilig how the unfinished wood product can be cut by a lumber breakdown system, comprising: grading an exteior of the unfinished wood product; determining a first plurality of price tables for which lumber may be recovered from the unfinished wood product based on the grading of the exterior of the unfinished wood product; measuring a length of the unfinished wood product; generating a stress wave in the unfinished wood product; determining a stress wave velocity in the unfinished wood product, the stress wave velocity being related to a modulus of elasticity of the lumber to be cut from the unfinished wood product; selecting a lumber price table from the first plurality of price tables based on the determined stress wave velocity, the price table relating lumber dimensions having the predicted modulus of elasticity to a current market value; and :providing the selected price table to the lumber breakdown system that determines a set of dimensions of the unfinished wood product and computes how the 20 unfinished wood product should be cut to maximize the value of the lumber recovered from the unfinished wood product, The method of claim 1 wherein the step of generating a stress wave in the unfinished wood product comprises striking the unfinished wood product with a hamnmer. 3. The method of claim I or 2 wherein the step of determining the stress wave veldcity further comprises the steps of: monitoring vibrations from the unfinished wood product with a transducer; receiving a signal from the transducer that is produced by the stress wave; searching the signal from the transducer in the time domain for successive amplitude peaks representing a reflection of the stress wave generated in the unfinished wood product; determining an elapsed time between the successive peaks; and from the elapsed time and the length of the unfinished wood product, determining the stress wave velocity. COMS ID No: SBMI-01106640 Received by IP Australia: Time 15:20 Date 2005-02-04 4.FEB.2005 15:22 PHILLIPS ORM FITZ 61299294511 N0.524 P.19/24 II 4, The method of any one of claims 1 to 3 wherein the step of determining the stress wave velocity fbrther comprises the steps of: monitoring vibrations from the unfinished wood product with a transducer; receiving a signal from the transducer that is produced by the stress wave; converting the signals received from the transducer into a frequency spectrum; searching the frequency spectrum for resonant frequencies caused by the stress wave generated in the unfinished wood product; and from the resonant frequencies and the length of the unfinished wood product, determining the stress wave velocity, 5, The method of claim 4 wherein the step of searching the frequency spectrum for the resonant frequencies comprises the step of searching the spectrum between a minimum and a maximum expected fiequency that are related to expected minimum and maximum stress wave velocities for the length of the unfinished wood product. 6, The method of any one of claims I to 5 which the unfinished wood product is a log,
2. 7. The method of any one of claims I to 5 in which the unfinished wood product is a cant. S: 8, The method of any one of claims 1 to 5 in which the unfinished wood product is a side board.
3. 9. A system for predicting a modulus of clasticity of lumber to be cut from a unfinished wood product and to use the predicted modulus of elasticity in determining how the unfinished wood product can be cut by and optimized by a unfinished wood product breakdown system, comprising; grading an exterior of the unfinished wood product; determining a first plurality of price tables for which lumber may be recovered from the unfinished wood product based on the grading of the exterior of the unfinished wood product; a measurement system that determines a length of the unfinished wood product; a hammer that selectively strikes the unfinished wood product to impart a stress wave in the unfiished wood product; a sensor that measures vibrations in the unfinished wood product from the stress wave; a computer system that receives signals from the sensor and determines a velocity of the stress wave that is related to the modulus of elasticity of the lumber to be cut from the unfinished wood product, the computer system selecting a lumber price COMS ID No: SBMI-01106640 Received by IP Australia: Time 15:20 Date 2005-02-04 4.FEB.2005 15:23 4.FEB2005 5:23 PHILLIPS ORM FITZ 61299294511 N.2 .02 NO.524 P.2e/24 12 table from the first plurality of price tables based anthe predicted modulus of elasticity, wherein the lumber price table relates lumber dimensions having the predicted modulus of elasticity to a current market value, the computer system fiuther providing the seleeted lumber price table to the lumber breakdown system to determine how the unfinished wood product should be out to maximize the value of the lumber recovered from the unfinished wood product. The system of claim 9 wherein computer system converts the signals received from the sensor into a frequency spectrum and searches the frequency spectrum for the resonant frequencies caused by the stress wave induced in the unfinished wood product. t0 11. The system of claim 9 or 10 wherein the sensor is an accelerometer.
4. 12. The system4 of claim I I wherein the accelerometer is mounted in a sensor tube and wherein the accelerometer is mounted to the sensor tube with a isolation gasket to shield the accelerometer from extraneous vibrations,*
5. 13. The system of any one of claims 9 to 12 In which the unfinished wood product is is a log. :14. The system of any one of clais 9 to 12 in which the unfinished wood product is :aacant. The system of any one ofeclaims 9 to 12 in which the unfinished wood product is a side board.
6. 16. A method of processing boards from a primary breakdown system in a sawmill com'prising: grading an exterior of the board; determining a firist plurality of price tables for which lumber may be recovered from the board based on the grading of the exterior of the board; measuing 4lengthbof the board, geneatig astrss avein the board; determining a stress wave velocity in the board, the stress wave velocity being related to a modulus of elasticity of the board: selecting a price table from the first plurality Qf price tables based on the 3o predicted modulus of elasticity: the price table relating wood products having the predicted modulus of elasticity to a current market value; and processing the board in accordance with the selected price table such that a value of the wood products produced from the board is maximized.
7. 17. The method of claim 16 in which the boards are cant boards.
8. 18. The method claim 16 in which the boards are side boards. COMS ID No: SBMI-01108840 Received by IP Australia: Time 15:20 Date 2005-02-04 4.FEE.2005 15:23 4.FTB2005 5:23 PHILLIPS ORM FITZ 61299294511 N.2 .12 NO.524 P.21/24 13
9. 19. A method of processing unfinished lumber on a trimmer system in a sawmill comprng: grading an exterior of the unfinished lumber; determinig a first plurality of price tables for which lwnber may be recovered from the lumber based on the grading of the exterior of the lumber, measuring a length of a piece of unfinished lumber; generating a stress wave in the unfinished lumber-, determining a stress wave velocity in the unfinished lumber, the stress wave velocity being related to a predicted modulus of elasticity of the unfnshed lumber; selecting a price table from the firt plurality of price tgbles based on the predicted modulus of elasticity; the price table relating wood products having the predicted modulus of elasicity to a current market value; and processig the unfinished lumber with the triummer system in accordance with the selected price table such that a value of the wood products produced from the unfinished lumber is maximized. A method of processing unfinished wood products on a tree stem merchandiser in a sawmill comprising: :grading an exterior of the unfinished wood product; etermining a first plurality of price tables for which lumber may be recovered 20 froma the unfiihed wood product based on the grading of the exterior of the unfinished wood product; :measuring a lenigth of the unfinished wood product; generating a stress wave in the unfinished wood product; determining a stress wave velocity in the unfinished wood product, the stress wave velocity being related to arnodulus of elasticity of the tree stem; selecting a price table fronm the first plurality of price tables based on a predicted modulus of elasticity, the price table relating wood products having the predicted modulus of elasticity to a current market value; and processing the unfinished wood product such that a value of the wood products produced from the unfinisbed wood product is maximized.
10. 21. The method of claim 20 in which the unfinished wood product is a log.
11. 22. The method of claim 20 in which the unfinished wood product is a cant.
12. 23. The method of claim 20 in which the unfinished wood product is a side board.
13. 24. A method of predicting one or more structural properties of lumber to be out from an unfinished wood product and to use the one or maore predicted structural COMS ID No: SBMI-01106640 Received by IF Australia: Time 15:20 Date 2005-02-04 4.FEB.2005 15:23 4.FEB2005 5:23 PHILLIPS ORM FITZ 61299294511 N.2 .22 NO.524 P.22/24 14 properties in determining bow the unfinished wood product can be cut by a lumrber breakdown system, comprising: grading an exterior of the unfinished wood product determining a first plurality of price tables for which lumber may be recovered s from the unfinished wood product based on the grading of the exterior of the unifinished wood product; measuring a length of the unfinished wood product generating a stress wave in the u.nfinished wood product; determining a stess wave velocity in the unfinished wood product, the stress wave velocity being related to a modulus of elasticity of the lumber to be cut from the unfinished wood product; selecting a lumber price table from a first plurality of price tables based on the determined stress wave velocity, the price table relating lumber dimensions having the predicted modulus of elasticity to a current inariet value; and providing the selected price table to the lumber breakdown system that determines 4 Set of dimensions of the unfinished wood product and computes how the unflnished wood product should be cut to maximize the value of the lumber recovered from the unfi-nished wood product substantially as herein described with reference to the accompaying drawings. *25. A system for predicting a modulus of elasticity of lumber to be cut from a 20 unfinished wood product and to use the predicted modulus of elasticity in determining how the unfinished wood product can be cut by and optimized by a unfinished wood product breakdown system, comprising: grading an exterior of the unfinished wood product; determining a first plurality of price tables for which ltumber may be recovered from the unfinished wood product based on the grading of the exterior of the 9 unfinished wood product; a measurement system that determines a l ength of the unfinished wood product; a hamrmer that selectively strikes the unfinished wood product to impart a stress wave in the unfinished wood product; 4 sensor that measures vibrations in the unfinished wood product from the stress wave; a computer systein that receives signals from the sensor and determines a velocity of the stress wave that is related to the modulus of elasticity of the lumber to be cut from the unfinished wood product, the computer system selecting a lumber price table from the first plurality of price tables based on the predicted modulus of elasticity, COMS ID No: SBMI-01106640 Received by IP Australia: Time 15:20 Date 2005-02-04 4. FEB.20:0I5 15:24 PHILLIPS ORM FITZ 61299294511 NO. 524 P.23/ 24 wherein the lumber price table relates lumber dimensions having the predicted modulus of elasticity to a curr=t mlarlCet value, the oompute? system further providing the selected lumber price table to the lumber breakdown system to determine how the unfinished wood product should be cut to maximize the value of the lumber recovered s from the unfipished wood product substantially as herein described with reference to the accompanying drawings. 26, A method of processing boards from a primary breakdown system in a sawmill comprising: grading an exterior of the board; determining a first plurality of price tables for which lumber may be recovered from the board based on the grading of the exterior of the board; measuring a length of the board; generating a stress wave in the board; determining a stress wave velocity in the board, the stress wave velocity being related to a modulus of elasticity of the board; selecting a price table from the first plurality of price tables based on the predicted modulus of elasticity; the price table relating wood products having the predicted modulus of elasticity to a current market value; and processing the board in accordance with the selected price table such that a value 20 of the wood products produced from the board is maximized substantially as herein •described with reference to the accompanying drawings.
14. 27. A method of processing unfinished lumber on a trimmer system in a sawmill *see. comprising; :grading an exterior of the unfinished lumber; determining a first plurality of price tables for which lumber may be recovered from the unfinished lumber based on the grading of the exterior of the unfinished lumber; measuring a length of a piece of unfinished lumber; generating a stress wave in the unfinished lumber; determining a stress wave velocity in the unfinished lumber, the stress wave velocity being related to a predicted modulus of elasticity of the unfinished lumber; selecting a price table from the first plurality of price tables based on the predicted modulus of elasticity; the price table relating wood products having the predicted modulus of elasticity to a current market value; and COMS ID No: SBMI-01106640 Received by IP Australia: Time 15:20 Date 2005-02-04 4.FEB.2005 15:24 PHILLIPS ORM FITZ 61299294511 N0.524 P.24/24 16 processipig the unfinished lumber with the trimmer system in accordance with the selected price table such that a value of the wood products produced from the unfinished lumber is maximized substantially as herein described with reference to the accompanying drawings.
15. 28. A method of processing unfinished wood products on a tree stem merchandiser in a sawmill comprising: grading an exterior of the unfinished wood product; determining a first plurality of price tables for which lumber may be recovered from the unfinished wood product based on the grading of the exterior of the unfinished wood product; measuring a length of the unfinished wood product; generating a stress wave in the unfinished wood product; determining a stress wave velocity in the unfinished wood product, the stress wave velocity being related to a modulus of elasticity of the tree stem; selecting a price table from the first plurality of price tables based on a predicted modulus of elasticity, the price table relating wood products having the predicted modulus of elasticity to a current market value; and processing the unfinished wood product such that a value of the woo4 products produced from the unfinished wood product is maximized substantially as herein 20 described with reference to the accompanying drawings. 4" Dated: 4 Februay 20 0 PHILLIPS ORMONDE FITZPATRICK 0g 0 Attorneys for: Weyerhaeuser Company a COMS ID No: SBMI-01106640 Received by IP Australia: Time 15:20 Date 2005-02-04