EP1432982A1 - Device and method for detecting defects in a wood or wood-based product from its acoustic signature - Google Patents
Device and method for detecting defects in a wood or wood-based product from its acoustic signatureInfo
- Publication number
- EP1432982A1 EP1432982A1 EP02783210A EP02783210A EP1432982A1 EP 1432982 A1 EP1432982 A1 EP 1432982A1 EP 02783210 A EP02783210 A EP 02783210A EP 02783210 A EP02783210 A EP 02783210A EP 1432982 A1 EP1432982 A1 EP 1432982A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- brushes
- wood
- excitation
- detection device
- signal
- Prior art date
- Legal status (The legal status 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 status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
- G01N29/4409—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison
- G01N29/4436—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison with a reference signal
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/045—Analysing solids by imparting shocks to the workpiece and detecting the vibrations or the acoustic waves caused by the shocks
-
- 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
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/01—Indexing codes associated with the measuring variable
- G01N2291/015—Attenuation, scattering
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/023—Solids
- G01N2291/0238—Wood
Definitions
- the present invention relates to a device and method for real-time detection of faults in a wooden or wood-based manufactured object.
- Optimizing the industrial manufacturing stages in the wood sector requires increased quality control of the products upstream of the production chain. Indeed, a manufacturing defect detected at an early stage in the production chain will only entail a limited cost for its treatment. This search for optimization also responds to a concern for quality assurance and compliance with strict specifications of the products produced.
- the type of defect that one wishes to detect consists mainly of inhomogeneities in a wooden or wood-based product. These can result from the separation of a material into two or more layers, from the presence of inclusion, from singularity, or from a lack of connection between two or more layers of a laminated or plated material. These are commonly called “delaminations”.
- a first type of device allows direct and localized measurement of the density of the wood product using X-rays (Lanvin JD. Et al. (1998) Classification of structural wood using an X-ray densimeter, J.
- a non-destructive detection method for delaminations is also known (US Patent 3,937,065) in which the surface of an object to be tested is subjected to transverse shocks ("tapping mode") at a frequency of 60 Hz and detects the acoustic response emitted by the object.
- transverse shocks "tapping mode"
- this method of probing the surface of the object is not continuous, its application to the detection of defects in wood products at an industrial level is unsuitable.
- the objective of the present invention is therefore to propose a device and a method that is simple in their design and in their operating mode, rapid and economical for detecting faults in an object in real time.
- the invention relates to a device for detecting faults in an object comprising: - means for local excitation of the surface of the object,
- the means of local excitation of the surface of the object comprise at least one rubbing element.
- rubbing element means an element which, brought into contact with an object to be tested, is subjected to friction with the latter. Continuous contact is maintained by the pressure exerted by the element on the object to be tested, the latter being moved relative to said element, or vice versa.
- object any wooden or wood-based product.
- the rubbing elements comprise brushes
- the length and thickness of the bristles of the brush are adapted to bring their resonant frequency closer to the resonant frequency characteristic of defects;
- the detection means include vibration sensors placed near the friction elements;
- the rubbing elements are brushes and the detection means comprise vibration sensors coupled to the brushes;
- the invention also relates to a method for detecting faults in an object in which:
- - at least one rubbing element is used to excite the surface of the object tested, - the signal detected on a computer is processed digitally and in real time,
- FIG. 1 is a schematic representation of the device for detecting faults in an object, according to the invention.
- the time signal 14 constitutes the reference - its maximum amplitude calculated over a time interval can constitute a detection threshold - the time signal 15 is measured when the rubbing element meets a defect;
- FIG. 3 is a schematic top view of a plaice having a defect related to the bonding lines.
- inhomogeneity 1 can, for example, be a node in wood, inclusion or delamination in a material consisting of laminated or plated layers, this type of defect 1 being, in general, hidden.
- the fault detection device 1 is based on the analysis of the vibrational response of an object 2 under the action of continuous excitation.
- the device therefore comprises means of local excitation of the surface 3 of the object 2 comprising at least one rubbing element 4 (see FIG. 1).
- the means of local excitation of the surface 3 of the object 2 include brushes.
- These brushes include bristles 5 fixed to a plate-type support 6.
- These bristles 5 are mainly defined by their length, their section and their intrinsic properties (density, Young's modulus, etc.).
- these bristles 5 are metallic.
- the friction elements 4 When using several friction elements 4 to obtain a characterization of the object 2 tested, no longer linear, therefore one-dimensional, but planar (two dimensions), the friction elements 4 are offset with respect to each other in the axis of advancement of said object 2. This positioning makes it possible to avoid possible interactions between the friction elements 4.
- the detection means comprise, in one embodiment, a vibration sensor 7 placed near a friction element 4. In a preferred embodiment, these vibration sensors are microphones. In the case where several rubbing elements 4 are used, the microphones 7 are chosen to be directional and are placed in close proximity to each rubbing element 4 and to the object 2.
- the acoustic signal being detected by a microphone 7, with a bandwidth of 30 Hz to 20,000 Hz, it is seen to transform a variation in sound pressure into a variation in analog voltage of the order of 50 mV.
- This electrical signal is received on an acquisition card 8. It is first filtered, amplified and then digitized, using an analog / digital converter 9. This signal is finally processed by a micro- computer 10 or any computer system capable of processing information.
- scrolling means 1 1 make it possible to advance the object 2 at constant speed relative to the excitation and detection means. In another embodiment, scrolling means 1 1 make it possible to advance excitation and detection means at constant speed relative to the object 2.
- these scrolling means 1 1 comprise scrolling rollers. The running speed is between 0 and 50 m per minute.
- the elements of the device according to the invention cannot be limited to the above description and are liable to modifications with the evolution of technologies.
- the use of microphones 7 as detection means can for example be replaced by the use of vibration sensors directly coupled to the brushes.
- these vibration sensors are then accelerometers.
- Other rubbing elements 4 can also be used, in the context of the invention, such as styli, pads, tongues.
- the invention also relates to a method for detecting faults 1 in an object 2 in which the surface 3 of the object 2 to be tested is locally excited by means of at least one friction element 4. This local excitation of the surface 3 of object 2 is continuous.
- the friction elements 4 advantageously include brushes.
- the acoustic response emitted by the object 2 is then detected by detection means.
- the latter comprise, in a preferred embodiment, vibration sensors 7 placed near the friction elements 4.
- these vibration sensors are microphones.
- the object 2 is scrolled at a controlled speed with respect to the excitation and detection means.
- the excitation and detection means are scrolled at a controlled speed with respect to the object 2.
- the acoustic signal detected on a computer 10 is sent in real time, as well as the scrolling speed. of the object or means of excitation and detection to take it into account during digital processing.
- this signal is digitally processed using software and a representation of the signal by its amplitude 12 over time 13 is displayed in real time on a display window.
- the signal is automatically detected by fixing a detection threshold, either on the amplitude of the time signal, or on its frequency representation.
- the acoustic signature 14 characteristic of one of said objects 2 does not have any defects 1. This prior calibration from a healthy object 2 therefore makes it possible to compare the amplitude of the acoustic signal measured 1 5 for each of the objects 2 in the set with said signature 14.
- the abscissa axis 13 represents the time scale (s) of the ordinate axis 12, the amplitude scale (in arbitrary units).
- a theory has been developed to explain the amplification of the vibrational modes resulting from inhomogeneities 1. This theory refers to a coupling between the vibration modes of the brush and those of the object 2 to be tested. These modes being close to each other, we would witness resonance phenomena making the detection of inhomogeneities 1 very easy. We search therefore to adapt the length and thickness of the bristles 5 of the brush before any measurement of a set of objects 2, in order to bring their frequencies closer to the specific frequencies of the defects 1. The surface 3 of the object 2 having a resistance to friction, the bristles 5 of said brushes are vibrated.
- the first is that of the bristles in contact with the surface 3 of the object 2.
- the excitation of these bristles is generated by their friction with the surface 3.
- the second type of vibration of the bristles 5 relates to those which, without contact with the surface 3, are excited by their neighbors.
- a simplified approach for determining the natural frequencies of vibrations of the bristles 5 of the brush then consists in modeling said bristles 5 using the assumptions and the Bernoulli model in beam dynamics.
- Boundary conditions are also taken into account, ie the beam is either "embedded-free” for a pile 5 not in contact with the surface 3 of the object 2, or "embedded-pressed” for a pile 5 in contact with the surface 3.
- This device and this method can advantageously be used for non-destructive industrial control of assembled pieces of wood and wood-based products.
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Wood Science & Technology (AREA)
- Food Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR0112338A FR2830082B1 (en) | 2001-09-25 | 2001-09-25 | DEVICE AND METHOD FOR DETECTING DEFECTS IN A WOODEN OR WOOD-BASED PRODUCT FROM ITS ACOUSTIC SIGNATURE |
FR0112338 | 2001-09-25 | ||
PCT/FR2002/003272 WO2003027670A1 (en) | 2001-09-25 | 2002-09-25 | Device and method for detecting defects in a wood or wood-based product from its acoustic signature |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1432982A1 true EP1432982A1 (en) | 2004-06-30 |
Family
ID=8867598
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP02783210A Withdrawn EP1432982A1 (en) | 2001-09-25 | 2002-09-25 | Device and method for detecting defects in a wood or wood-based product from its acoustic signature |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1432982A1 (en) |
CA (1) | CA2461506C (en) |
FR (1) | FR2830082B1 (en) |
WO (1) | WO2003027670A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102005016738B4 (en) * | 2005-04-11 | 2010-01-07 | Minda Industrieanlagen Gmbh | Method and device for non-destructive testing of wood components |
FR2932268B1 (en) * | 2008-06-06 | 2017-11-17 | Cryospace Air Liquide Aerospatiale | METHOD AND INSTALLATION FOR NON-DESTRUCTIVE CONTROL OF THE ADHESION OF A GLUE COATING ON A SUPPORT |
CN109738524B (en) * | 2019-01-30 | 2021-07-30 | 南京林业大学 | System for evaluating internal quality of broad-leaved wood log and application |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4854172A (en) * | 1988-09-22 | 1989-08-08 | Regents Of The University Of California | Method and apparatus for measurement of density profiles in wood composites, using acoustic emission |
GB8826640D0 (en) * | 1988-11-15 | 1988-12-21 | Sensotect Ltd | Apparatus for determining surface roughness of material |
US5691476A (en) * | 1993-09-07 | 1997-11-25 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Method for ultrasonic imaging and device for performing the method |
GB9710719D0 (en) * | 1997-05-24 | 1997-07-16 | Ncr Int Inc | A system for authenticating printed documents |
US6088547A (en) * | 1999-07-16 | 2000-07-11 | Hewlett-Packard Company | Automatic fuser temperature control |
US6276209B1 (en) * | 1999-09-30 | 2001-08-21 | Perceptron, Inc. | System and method of assessing the structural properties of wooden members using ultrasound |
-
2001
- 2001-09-25 FR FR0112338A patent/FR2830082B1/en not_active Expired - Fee Related
-
2002
- 2002-09-25 CA CA2461506A patent/CA2461506C/en not_active Expired - Fee Related
- 2002-09-25 EP EP02783210A patent/EP1432982A1/en not_active Withdrawn
- 2002-09-25 WO PCT/FR2002/003272 patent/WO2003027670A1/en not_active Application Discontinuation
Non-Patent Citations (1)
Title |
---|
See references of WO03027670A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO2003027670A1 (en) | 2003-04-03 |
FR2830082A1 (en) | 2003-03-28 |
FR2830082B1 (en) | 2004-02-20 |
CA2461506C (en) | 2012-11-13 |
CA2461506A1 (en) | 2003-04-03 |
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AX | Request for extension of the european patent |
Extension state: AL LT LV MK RO SI |
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RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: GUILLEMAIN, PHILIPPE Inventor name: GRENIER, DAVIDC/O MR. GRENIER RAYMOND Inventor name: BRANCHERIAU, LOICLOTISSEMENT LE CLOS DES OLIVIERS Inventor name: BAILLERES, HENRI Inventor name: KRONLAND-MARTINET, RICHARD Inventor name: CALCHERA, GILLES Inventor name: LANVIN, JEAN-DENIS |
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17Q | First examination report despatched |
Effective date: 20100324 |
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STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
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18D | Application deemed to be withdrawn |
Effective date: 20180404 |
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RIC1 | Information provided on ipc code assigned before grant |
Ipc: G01N 29/14 20060101ALI20030410BHEP Ipc: G01N 29/04 20060101ALI20030410BHEP Ipc: G01N 33/46 20060101AFI20030410BHEP |