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Svenman, E. & Runnemalm, A. (2017). A complex response inductive method for improved gap measurement in laser welding. The International Journal of Advanced Manufacturing Technology, 88(1-4), 175-184
Open this publication in new window or tab >>A complex response inductive method for improved gap measurement in laser welding
2017 (English)In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 88, no 1-4, p. 175-184Article in journal (Refereed) Published
Abstract [en]

Laser welding needs precise measurement of weldgap position to avoid weld defects. Most often, optical measurement methods are used, but well-aligned narrow gaps canbe difficult to detect. An improved inductive method capable of detecting zero gaps in square butt joints is proposed. The new method uses two eddy current coils, one on each side of the gap, and measures the complex response of the individual coils, i.e. both the inductive and resistive response. By combining the coil responses, both the position and the geometry of the weld gap can be estimated. The method was experimentally investigated by traversing a single coil over an adjustable gap between two plates and combining the measured coil responses into a simulated two-coil probe. The gap was adjusted in both misalignment and gap width up to 0.4 mm. Comparing the results to known settings and positions shows that gap position is measured to within 0.1 mm, if the probe is within a working area of 1 mm from the gap in both position and height. Results from the new method were compared to simulations, from the same experimental data, of a previously reported method where the coils were electrically combined by wiring them together. The previous method can give accurate results but has a much smaller working area and depends on servo actuation to position the probe above the gap. The improved method gives better tolerance to varying misalignment and gap width, which is an advantage over previous inductive methods.

Keywords
Seam tracking, Inductive, Complex response, Zero-gap measurement, Laser beamwelding, Square butt joint
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-10146 (URN)10.1007/s00170-016-8750-x (DOI)000392308400016 ()2-s2.0-84964330115 (Scopus ID)
Funder
Knowledge Foundation
Available from: 2016-11-17 Created: 2016-11-17 Last updated: 2019-05-23Bibliographically approved
Svenman, E. & Runnemalm, A. (2017). Model based compensation of systematic errors in an inductive gap measurement method. Measurement : Journal of the International Measurement Confederation, 105, 17-24
Open this publication in new window or tab >>Model based compensation of systematic errors in an inductive gap measurement method
2017 (English)In: Measurement : Journal of the International Measurement Confederation, ISSN 0263-2241, Vol. 105, p. 17-24Article in journal (Refereed) Published
Abstract [en]

This paper presents an improvement to a recently presented inductive gap measurement method, using a model to reduce systematic errors. Gap measurement is important in laser keyhole welding, where the laser beam and the resulting weld seam are very narrow, requiring high precision in alignment and gap preparation. The previously reported method for gap measurement uses one inductive coil on each side of the gap, each measuring distance to the gap and lift off above a plate, to estimate the position, width and alignment of the gap in a square butt joint. The method can detect zero width gap and shows position error less than 0.1 mm, but gap width and alignment measurement suffer from systematic errors. The improvement is based on a model that is designed to describe these systematic errors as functions of the gap dimensions. The model relies on observations of experimental data, and is calibrated to a small set of measurements. Using the model with the initial estimate of the gap dimensions to compensate the coil measurements, an improved estimate of the gap dimensions can be calculated. The errors in the compensated results are within 0.1 mm except for gap width, which still suffers from the effect of combined gap width and misalignment.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Seam tracking, inductive, complex response, zero gap, laser beam welding, error compensation
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-10148 (URN)10.1016/j.measurement.2017.03.043 (DOI)000401378400003 ()2-s2.0-85017174867 (Scopus ID)
Funder
Knowledge Foundation
Note

Ingår i lic. uppsats

Available from: 2016-11-17 Created: 2016-11-17 Last updated: 2019-05-23Bibliographically approved
Broberg, P. & Runnemalm, A. (2016). Analysis algorithm for surface crack detection by thermography with UV light excitation. In: Kaczmarek, M. & Bujnowski, A. (Ed.), Quantitative InfraRed Thermography 2016: Abstracts. Paper presented at 13th Quantitative InfraRed Thermography, Gdańsk, Poland, July 4-8, 2016 (pp. 144-149). Gdańsk, Poland: Publishing Gdańsk University of Technology
Open this publication in new window or tab >>Analysis algorithm for surface crack detection by thermography with UV light excitation
2016 (English)In: Quantitative InfraRed Thermography 2016: Abstracts / [ed] Kaczmarek, M. & Bujnowski, A., Gdańsk, Poland: Publishing Gdańsk University of Technology , 2016, p. 144-149Conference paper, Published paper (Refereed)
Abstract [en]

Surface crack defects can be detected by IR thermograpgy due to the high absorption of energy within the crack cavity. It is often difficult to detect the defect in the raw data, since the signal easily drowns in the background. It is therefore important to have good analysis algorithms that can reduce the background and enhance the defect. Here an analysis algorithm is presented which significantly increases the signal to noise ratio of the defects and reduces the image sequence from the camera to one image.

Place, publisher, year, edition, pages
Gdańsk, Poland: Publishing Gdańsk University of Technology, 2016
National Category
Production Engineering, Human Work Science and Ergonomics Manufacturing, Surface and Joining Technology Metallurgy and Metallic Materials
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-10130 (URN)
Conference
13th Quantitative InfraRed Thermography, Gdańsk, Poland, July 4-8, 2016
Available from: 2016-11-10 Created: 2016-11-10 Last updated: 2019-03-15Bibliographically approved
Runnemalm, A., Broberg, P., Garcia de la Yedra, A., Fuente, R., Beizama, A. M., Fernandez, E., . . . Henriksson, P. (2016). Automated inspection of welds with limited access by use of active thermography with laser line excitation. In: : . Paper presented at 19th World Conference on Non-Destructive Testing 2016. , Article ID 19664.
Open this publication in new window or tab >>Automated inspection of welds with limited access by use of active thermography with laser line excitation
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2016 (English)Conference paper, Published paper (Other academic)
Abstract [en]

Inspection of welds for detecting surface breaking defects is traditionally performed by using NDT methods such as Fluorescent Penetrant Inspection, Visual Inspection or Eddy Current. All those well-known techniques have drawbacks, as they need access to the surface, either for preparation with e.g. liquids or for using contact probes. Traditional methods also require a skilled operator to carry out the inspection, and moreover to analyse the obtained results. Furthermore, for the inspection of welds with limited access, the use of those traditional methods is even more complex, resulting in increased inspection time and reduced detection capability or in worst case, areas impossible to inspect. Therefore, the development of a fully automated non-contact method overcoming these limitations is desired. ;Active thermography is a novel NDT technique for weld inspection. The method has shown promising results for replacing traditional techniques when it comes to detection of surface breaking defects in metals. The method make use of an excitation source in order to heat the sample in a controlled manner during the test, and an infrared thermal camera for recordings of the thermal evolution. ;In this work, an automated solution developed and demonstrated for inspection of welds in a jet-engine component with limited access is presented. The NDT system is mounted on an industrial robot, making it possible to automatic scan the inspected area. The system consists of a, continuous laser-line excitation source together with a FLIR SC 655 microbolometer thermographic camera. In order to access limited areas, two polished aluminium mirrors have been used for both infrared radiation monitoring and laser excitation respectively. A solution for automatic analysing, defect detection and sizing is also included and presented.

Keywords
Welding, surface, inspection
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-10560 (URN)
Conference
19th World Conference on Non-Destructive Testing 2016
Available from: 2017-01-12 Created: 2017-01-12 Last updated: 2018-08-12Bibliographically approved
Bergström, P., Fergusson, M., Folkesson, P., Runnemalm, A., Ottosson, M., Andersson, A. & Sjödahl, M. (2016). Automatic in-line inspection of shape based on photogrammetry. In: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings: 25th – 27th of October 2016. Paper presented at 7th International Swedish Production Symposium, SPS16, Lund, Sweden, October 25–27, 2016 (pp. 1-9). Lund: Swedish Production Academy
Open this publication in new window or tab >>Automatic in-line inspection of shape based on photogrammetry
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2016 (English)In: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings: 25th – 27th of October 2016, Lund: Swedish Production Academy , 2016, p. 1-9Conference paper, Published paper (Refereed)
Abstract [en]

We are describing a fully automatic in-line shape inspection system for controlling the shape of moving objects on a conveyor belt. The shapes of the objects are measured using a full-field optical shape measurement method based on photogrammetry. The photogrammetry system consists of four cameras, a flash, and a triggering device. When an object to be measured arrives at a given position relative to the system, the flash and cameras are synchronously triggered to capture images of the moving object.From the captured images a point-cloud representing the measured shape is created. The point-cloud is then aligned to a CAD-model, which defines the nominal shape of the measured object, using a best-fit method and a feature-based alignment method. Deviations between the point-cloud and the CAD-model are computed giving the output of the inspection process. The computational time to create a point-cloud from the captured images is about 30 seconds and the computational time for the comparison with the CAD-model is about ten milliseconds. We report on recent progress with the shape inspection system.

Place, publisher, year, edition, pages
Lund: Swedish Production Academy, 2016
Keywords
Automatic, full-field, in-line, photogrammetry, shape inspection, single-shot
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-10249 (URN)
Conference
7th International Swedish Production Symposium, SPS16, Lund, Sweden, October 25–27, 2016
Available from: 2016-12-08 Created: 2016-12-08 Last updated: 2018-08-12Bibliographically approved
Sikström, F., Runnemalm, A., Broberg, P., Nilsen, M. & Svenman, E. (2016). Evaluation of non-contact methods for joint tracking in a laser beam welding application. In: The 7th International Swedish Production Symposium, Conference Proceedings: 25th – 27th of October 2016. Paper presented at 7th Swedish Production Symposium, Lund, Sweden, October 25-27, 2016 (pp. 1-6). Lund: Swedish Production Symposium
Open this publication in new window or tab >>Evaluation of non-contact methods for joint tracking in a laser beam welding application
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2016 (English)In: The 7th International Swedish Production Symposium, Conference Proceedings: 25th – 27th of October 2016, Lund: Swedish Production Symposium , 2016, p. 1-6Conference paper, Published paper (Other academic)
Abstract [en]

The use of automated laser welding is a key enabler for resource efficient manufacturing in several industrial sectors. One disadvantage with laser welding is the narrow tolerance requirements in the joint fit-up. This is the main reason for the importance of joint tracking systems. This paper describes anevaluation of four non-contact measurement methods to measure the position, gap width and misalignment between superalloy plates. The evaluation was carried out for increased knowledge about the possibilities and limitations with the different methods. The methods are vision-, laser-line-,thermography- and inductive probe systems which are compared in an experimental setup representing a relevant industrial application. Vision is based on a CMOS camera, where the image information is used directly for the measurements. Laser-line is based on triangulation between a camera and a projected laserline. Thermography detects the heat increase in the gap width due to external heat excitation. Inductive probe uses two eddy current coils, and by a complex response method possibilities to narrow gap measurement is achieved. The results, evaluated by comparing the data from the different systems, clearly highlights possibilities and limitations with respective method and serves as a guide in the development of laser beam welding.

Place, publisher, year, edition, pages
Lund: Swedish Production Symposium, 2016
Keywords
Joint tracking, Gap width, Misalignment, Inductive coil, Thermography, Laser line, Vision sensor
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-10147 (URN)
Conference
7th Swedish Production Symposium, Lund, Sweden, October 25-27, 2016
Note

Ingår i lic.uppsats

Available from: 2016-11-17 Created: 2016-11-17 Last updated: 2019-05-10Bibliographically approved
Broberg, P., Sjödahl, M. & Runnemalm, A. (2015). Comparison of NDT-methods for automatic inspection of weld defects. International journal of materials & product technology, 50(1), 1-21
Open this publication in new window or tab >>Comparison of NDT-methods for automatic inspection of weld defects
2015 (English)In: International journal of materials & product technology, ISSN 0268-1900, E-ISSN 1741-5209, Vol. 50, no 1, p. 1-21Article in journal (Refereed) Published
Abstract [en]

The purpose of this study is to investigate different NDT-methods for weld inspection in an objective manner. Test objects are produced with known variation of flaws: internal pores, surface and internal cracks, toe radius and weld depth. The NDT-methods compared are: phased array ultrasound, radiography, eddy current, thermography and shearography. The results show that radiography is the better method for volumetric defects in thin plates while ultrasound is better for flat defects and thicker, non-flat plates. Thermography was shown to have a good ability of detecting surface defects. A combination of ultrasound and thermography results in a detection of all the non-geometrical defects investigated in this study.

Keywords
non-destructive testing, NDT, weld defects, automatic inspection
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-3113 (URN)10.1504/IJMPT.2015.066863 (DOI)000352133300001 ()2-s2.0-84921311226 (Scopus ID)
Projects
ANDTE
Available from: 2011-01-27 Created: 2011-01-27 Last updated: 2017-12-11Bibliographically approved
Fuente, R., García de la Yedra, A., Beizama, A. M., Fernández, E., Gorostegui Colinas, E., Echeverria, A., . . . Henrikson, P. (2015). Development and demonstration of an automated system for limited access weld inspection by using infrared active thermography. In: Proceedings 7th International Symposium on NDT in Aerospace: . Paper presented at 7th International Symposium on NDT in Aerospace,16 – 18 November 2015 Bremen, Germany (pp. 1-8). Berlin
Open this publication in new window or tab >>Development and demonstration of an automated system for limited access weld inspection by using infrared active thermography
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2015 (English)In: Proceedings 7th International Symposium on NDT in Aerospace, Berlin, 2015, p. 1-8Conference paper, Published paper (Refereed)
Abstract [en]

Weld inspection for surface breaking defects detection has been traditionally performed by using NDT methods such as Fluorescent PenetrantInspection (FPI), Visual Inspection (VI) or Eddy Currents (EC). All those well known techniques have as common drawback the need of skilled operator intervention in order to analyse obtained results. In the specific case of inspection of welds with limited access, the application of those traditional methods is even more complex, thus increasing inspection time and reducing the defect detection capability. Therefore, the development of a fully automated non-contact method overcoming these limitations is desired. Active thermography (IRT) represents one of the most promising techniques for replacing traditional techniques for surface breaking defect detection in welds.This technique makes use of an excitation source in order to heat the sample undertest and an infrared camera for thermal evolution monitoring. With the combination of these excitation-monitoring techniques, heterogeneities in the heat flow caused bysurface breaking cracks can be detected. In this work, a robotic solution was developed and demonstrated for the inspection of welds with real cracks in a representative environment with limited access. The system consists of a continuous laser-line excitation source together with a FLIR SC 655 micro bolometer thermographic camera. In order to access limited areas, two different aluminium polished mirrors have been used for bothinfrared radiation monitoring and laser excitation respectively. The inspection results, analysis and comparison with traditional methods will be shown.

Place, publisher, year, edition, pages
Berlin: , 2015
Keywords
Weldning, automated systems
National Category
Aerospace Engineering Production Engineering, Human Work Science and Ergonomics
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-9283 (URN)
Conference
7th International Symposium on NDT in Aerospace,16 – 18 November 2015 Bremen, Germany
Available from: 2016-04-04 Created: 2016-04-04 Last updated: 2018-08-12
Svenman, E., Rosell, A., Runnemalm, A., Christiansson, A.-K. & Henrikson, P. (2015). Weld gap position detection based on eddy current methods with mismatch compensation. In: Proceedings of JOM 18 International conference on joining materials, Helsingör, Danmark, april 26-29, 2015: . Paper presented at 18th International Conference on Joining Materials In association with the IIW Helsingør-Denmark, April 26 to 29, 2015 (pp. 1-9). JOM-institute
Open this publication in new window or tab >>Weld gap position detection based on eddy current methods with mismatch compensation
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2015 (English)In: Proceedings of JOM 18 International conference on joining materials, Helsingör, Danmark, april 26-29, 2015, JOM-institute , 2015, p. 1-9Conference paper, Published paper (Refereed)
Abstract [en]

The paper proposes a method for finding the accurate position of narrow gaps, intended for seam tracking applications. Laser beam welding of butt joints, with narrow gap and weld width, demand very accurate positioning to avoid serious and difficult to detect lack of fusion defects. Existing optical and mechanical gap trackers have problems with narrow gaps and surface finish. Eddy current probes can detect narrow gaps, but the accuracy is affected by mismatch in height above the surface on either side of the gap. In this paper a non-contact eddy-current method, suitable for robotic seam tracking, is proposed. The method is based on the resistive and inductive response of two absolute eddy current coils on either side of the gap to calculate a position compensated for height variations. Additionally, the method may be used to estimate the values of height and gap width, which is useful for weld parameter optimization. To investigate the response to variations in height, the method is tested on non-magnetic metals by scanning one commercially available eddy current probe across an adjustable gap and calculating the expected response for a two-probe configuration. Results for gap position are promising, while mismatch and gap width results need further investigation.

Place, publisher, year, edition, pages
JOM-institute, 2015
Series
JOM, ISSN 2246-0160
Keywords
laser welding, seam finding, inductive, eddy current
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-8991 (URN)
Conference
18th International Conference on Joining Materials In association with the IIW Helsingør-Denmark, April 26 to 29, 2015
Available from: 2016-02-04 Created: 2016-02-04 Last updated: 2018-08-12
Runnemalm, A., Ahlberg, J., Appelgren, A. & Sjökvist, S. (2014). Automatic Inspection of Spot Welds by Thermography. Journal of nondestructive evaluation, 33(3), 398-406
Open this publication in new window or tab >>Automatic Inspection of Spot Welds by Thermography
2014 (English)In: Journal of nondestructive evaluation, ISSN 0195-9298, E-ISSN 1573-4862, Vol. 33, no 3, p. 398-406Article in journal (Refereed) Published
Abstract [en]

The interest for thermography as a method for spot weld inspection has increased during the last years since it is a full-field method suitable for automatic inspection. Thermography systems can be developed in different ways, with different physical setups, excitation sources, and image analysis algorithms. In this paper we suggest a single-sided setup of a thermography system using a flash lamp as excitation source. The analysis algorithm aims to find the spatial region in the acquired images corresponding to the successfully welded area, i.e., the nugget size. Experiments show that the system is able to detect spot welds, measure the nugget diameter, and based on the information also separate a spot weld from a stick weld. The system is capable to inspect more than four spot welds per minute, and has potential for an automatic non-destructive system for spot weld inspection. The development opportunities are significant, since the algorithm used in the initial analysis is rather simplified. Moreover, further evaluation of alternative excitation sources can potentially improve the performance.

Keywords
Spot welds, Inspection, Non-destructive testing, Thermography
National Category
Engineering and Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-5992 (URN)10.1007/s10921-014-0233-0 (DOI)000340594600010 ()
Projects
SpotLight
Funder
Vinnova
Available from: 2014-03-04 Created: 2014-03-04 Last updated: 2019-05-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6933-375X

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