New Zealand inventors file US patent application for maximizing lumber recovery from a log using system that uses acoustic and X-ray technology to determine log elasticity, density, and provides cutting pattern based on stiffness profile

Wendy Lisney

January 10, 2014 (Politics & Government Week) – A patent application by the inventors PARKER, Jeffrey (Rotorua, NZ); LAUSBERG, Marco (Rotorua, NZ), filed on May 2, 2013, was made available online on January 2, 2014, according to news reporting originating from Washington, D.C., by VerticalNews correspondents.

This patent application is assigned to Wqi Limited.

The following quote was obtained by the news editors from the background information supplied by the inventors: "U.S. Pat. No. 6,889,551 discloses a method of lumber break down to maximise the value of the lumber recovered from a log or similar by a system which includes determining an acoustic velocity in the log to predict an average modulus of elasticity, determining density profile information, and utilising the stiffness profile in cutting the log, typically by generating a sawing pattern for the log.

"It is an object of the present invention to provide an improved method and apparatus for breaking down a tree stem, log, cant, flitch or slab to sawn timber, or to at least provide the public with a useful choice."

In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventors' summary information for this patent application: "In one aspect in broad terms the invention comprises a method of breaking down a stem, log, cant or slab which includes: determining an acoustic velocity value for the stem, log, cant or slab, determining density profile information using x-ray radiation across the width of the stem, log, cant or slab, including locating a position of minimum density in a stem, log, cant or slab, predicting a stiffness profile across the stem, log, cant or slab from the acoustic velocity and the density profile information across the stem, log, cant or slab, and utilising the stiffness profile in cutting the stem, log, cant or slab including locating a sawing pattern for the stem, log, cant or slab by locating a centre of the sawing pattern in a predetermined position relative to the determined position of minimum density of the stem, log, cant or slab. The method may include estimating elasticity or stiffness profile across the length of timber by calculating an initial profile of elasticity or stiffness across the timber using an elasticity model of the timber, and determining a revised elasticity or stiffness profile using the measured velocity, density information and initial elasticity profile and/or validating the elasticity or stiffness profile by calculating a velocity of a compression wave in the timber using the density information and elasticity or stiffness profile and comparing the calculated velocity with the measured velocity.

"Preferably determining density profile information using x-ray radiation includes moving the stem, log, cant or slab through at least one beam of x-ray radiation or moving at least one source of x-ray radiation relative to the stem, log, cant or slab.

"Preferably determining density profile information includes measuring x-ray radiation energy after propagating through a stem, log, cant or slab.

"Preferably the method further comprises generating a sawing pattern from the determination of the position of minimum density.

"In a second aspect the invention may broadly be said to consist of a method of breaking down a stem, log, cant or slab comprising the steps of: determining an acoustic velocity value for the stem, log, cant or slab, determining density profile information across the width of the stem, log, cant or slab, including locating a position of minimum density in a stem, log, cant or slab, predicting a stiffness profile across the stem, log, cant or slab from the acoustic velocity and the density profile information across the stem, log, cant or slab, and utilising the stiffness profile across the stem, log, cant or slab to generate a sawing pattern for cutting the stem, log, cant or slab.

"In one embodiment the method further comprises cutting the stem, log, cant or slab by locating a centre of the sawing pattern in a predetermined position relative to the determined position of minimum density of the stem, log, cant or slab.

"In one embodiment the step of predicting the stiffness profile across the stem, log, cant or slab comprises calculating an initial profile of stiffness across the stem, log, cant or slab from an elasticity model of the stem, log, cant or slab, and determining a stiffness profile using the acoustic velocity value for the stem, log, cant or slab, the density profile information and the initial stiffness profile.

"Preferably the method further comprises validating the stiffness profile by calculating a velocity of a compression wave in the stem, log, cant or slab from a velocity profile derived from the density profile information and the stiffness profile, and comparing the calculated velocity with the acoustic velocity value.

"Preferably the method further comprising adjusting the stiffness profile according to the comparison and validating the adjusted stiffness profile in accordance with the steps of claim 3.

"In one embodiment the step of determining density profile information includes subjecting the stem, log, cant or slab to x-ray radiation.

"Preferably determining density profile information further includes measuring the x-ray radiation energy level after propagating through the stem, log, cant or slab.

"The x-ray radiation may comprise a collimated beam, a diverging beam, a converging beam, or any combination thereof.

"The x-ray radiation may be provided by one or multiple radiation source(s).

"Preferably the method further comprising calibrating the x-ray radiation to an energy level prior to subjecting the stem, log, cant or slab to the x-ray radiation. Preferably calibrating the x-ray radiation comprises passing a control stem, log, cant or slab through the x-ray radiation and adjusting the x-ray radiation energy level to an appropriate energy level for the control.

"Preferably subjecting the stem, log, cant or slab to x-ray radiation comprises moving the stem, log, cant or slab through at least one beam of x-ray radiation. Alternatively subjecting the stem, log, cant or slab the step to x-ray radiation includes moving at least one source of x-ray radiation relative to the stem, log, cant or slab.

"In one embodiment the step of determining an acoustic velocity value of the stem, log, cant or slab comprises applying a force to the stem, log, cant or slab and measuring a frequency of vibration resulting from the applied force.

"Preferably the method further comprises forming one or more laser marker lines on the stem, log, cant, or slab in accordance with the sawing pattern and cutting the stem, log, cant or slab with a cutting machine in accordance with the marker lines.

"In a third aspect the invention may broadly be said to consist of a method of determining a stiffness profile of a stem, log, cant or slab comprising the steps of: determining an acoustic velocity value for the stem, log, cant or slab, determining density profile information across the width of the stem, log, cant or slab, including locating a position of minimum density in a stem, log, cant or slab, and predicting the stiffness profile across the stem, log, cant or slab from the acoustic velocity and the density profile information across the stem, log, cant or slab.

"In a fourth aspect the invention may broadly be said to consist of a system for breaking down a stem, log, cant or slab comprising: a measuring system configured to: determine an acoustic velocity value for the stem, log, cant or slab, and determine density profile information across the width of the stem, log, cant or slab, including locate a position of minimum density in a stem, log, cant or slab, and at least one processor configured to predict a stiffness profile across the stem, log, cant or slab from the acoustic velocity and the density profile information across the stem, log, cant or slab, for generating a sawing pattern for cutting the stem, log, cant or slab, wherein the sawing pattern is dependent on the position of minimum density of the stem, log, cant or slab.

"Preferably the system further comprises an output monitor for displaying the predicted stiffness profile across the stem, log, cant or slab.

"Preferably the measurement system comprises at least one x-ray radiation source and at least one x-ray radiation detector configured to locate on either side of the stem, log, cant or slab in a density measurement position of the stem, log, cant or slab in use, the at least one source configured to apply x-ray radiation energy through the stem, log, cant or slab and the at least one detector configured to receive and measure an energy level of x-ray radiation propagating through the stem, log, cant or slab, and the measurement system further comprising at least one processor configured to determine the density profile information from one or more energy levels measured by the at least one detector across the stem, log, cant or slab.

"Preferably the at least one source is located above the stem, log, cant, or slab in the density measurement position, and the at least one detector is located underneath the stem, log, cant or slab in the density measurement position.

"Preferably the measurement system comprises a compressed air driven hammer located adjacent the stem, log, cant or slab in an acoustic velocity measurement position of the stem, log, cant or slab in use and configured to strike the stem, log, cant or slab to stimulate vibration in said stem, log, cant or slab, and an accelerometer configured to locate against an end of the stem, log, cant or slab in the acoustic velocity measurement position in use, and output data relating to a frequency of the vibration, the measurement system further comprising at least one processor configured to determine the acoustic velocity value from the frequency data of the accelerometer.

"Preferably the system further comprises a cutting system including: a laser source configured to generate at least one laser marker cutting line on the stem, log, cant or slab corresponding to the sawing pattern, and a sawing machine configured to cut the stem, log, cant or slab in accordance with the at least one laser marker cutting line.

"Preferably the system further comprises a transport system configured to convey the stem, log, cant or slab in use first to a measurement stage associated with the measurement system and then to a cutting stage associated with the cutting system.

"The term 'comprising' as used in this specification and claims means 'consisting at least in part of'. When interpreting each statement in this specification and claims that includes the term 'comprising', features other than that or those prefaced by the term may also be present. Related terms such as 'comprise' and 'comprises' are to be interpreted in the same manner.

"As used herein the term 'and/or' means 'and' or 'or', or both.

BRIEF DESCRIPTION OF THE FIGURES

"The invention is further described with reference to the accompanying figures in which:

"FIG. 1 is a flow diagram which comprises schematic overview of the information and processing required for MoE estimation according to the invention.

"FIG. 2 is a flow diagram showing a preferred form methodology for estimating an MoE profile for a log or cant.

"FIGS. 3A-3C show density, MoE and velocity profiles respectively as a function of timber radius.

"FIG. 4A-4D show initial and revised MoE profiles as a function of timber radius.

"FIGS. 5A-5D show in further detail a preferred form method for estimating an MoE profile.

"FIG. 6 shows a graph of measured density profile information.

"FIG. 7A-7C show structural sawing patterns for a cant with a position of minimum density located at the geometrical centre.

"FIG. 8A-8B show a cant having a position of minimum density located offset from the geometrical centre and associated sawing patterns.

"FIG. 9 schematically illustrates a preferred form of apparatus of the invention in plan view.

"FIG. 10 schematically illustrates a preferred form of apparatus of the invention in perspective view.

"FIG. 11 shows a graph of the mean cant MoE for the group having high acoustic velocity."

URL and more information on this patent application, see: PARKER, Jeffrey; LAUSBERG, Marco. Method of Estimating Timber Stiffness Profiles. Filed May 2, 2013 and posted January 2, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=6268&p=126&f=G&l=50&d=PG01&S1=20131226.PD.&OS=PD/20131226&RS=PD/20131226

Keywords for this news article include: Wqi Limited.

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