On-Line Estimation of Laser Weld Penetration

1997 ◽  
Vol 119 (4) ◽  
pp. 791-801 ◽  
Author(s):  
Jay F. Tu ◽  
Kishore N. Lankalapalli ◽  
Mark Gartner ◽  
Keng H. Leong
Keyword(s):  
Penetration Depth ◽  
Finite Size ◽  
Depth Estimation ◽  
Process Models ◽  
Bottom Surface ◽  
Weld Penetration ◽  
Weld Quality ◽  
Laser Weld ◽  
Production Environment ◽  
On Line

High-power CO2 laser welding has been widely used in the industry because of its high productivity and excellent weld quality. In order to tap the potential of this process completely, it is important to have on-line weld quality inspection methods to improve the process productivity and reliability by achieving 100 percent weld inspection. Weld penetration is one of the most important factors critical to the quality of a laser weld. However, it is very difficult to directly measure the extent of penetration without sectioning the workpiece. In this paper a model-based penetration depth estimation technique suitable for the production environment is developed. The proposed model relates the temperature measured on the bottom surface of the workpiece, weld bead width, laser beam power and welding speed to penetration depth. The closed-loop depth estimator combines the model and a model-error compensator to compensate for the uncertainty in the measurement of the laser power and absorptivity. Other effects considered are the averaging due to the finite size of the sensor, delay based on the sensor location and the process and sensor dynamics. Several bead-on-plate and butt welds were made on low carbon steel plates to validate the static process models and the depth estimation scheme. Temperatures on the bottom surface of the workpiece during welding were measured using infrared thermocouples. The welds were sectioned longitudinally to obtain the penetration profile. The penetration profiles estimated by the depth estimator matched satisfactorily with the measured penetration profiles. The results validate the capability of the proposed depth estimator to estimate penetration depth and its ability to trace the dynamic changes in penetration depth.

scholarly journals Laser Weld Penetration Estimation Using Temperature Measurements

1999 ◽  
Vol 121 (2) ◽  
pp. 179-188 ◽  
Author(s):  
K. N. Lankalapalli ◽  
J. F. Tu ◽  
K. H. Leong ◽  
M. Gartner
Keyword(s):  
Penetration Depth ◽  
Plate Thickness ◽  
Bottom Surface ◽  
Process Conditions ◽  
Measured Signal ◽  
Weld Penetration ◽  
Laser Weld ◽  
Low Carbon ◽  
Conduction Model ◽  
Bead Width

Penetration depth is an important factor critical to the quality of a laser weld. This paper presents a 3D heat conduction model with a moving line source to correlate the temperature measured on the bottom surface of the workpiece to the weld penetration, weld bead width and welding speed. Temperatures on the bottom surface of the workpiece are measured using infrared thermocouples located behind the laser beam. The averaging effect due to the temperature measurement spot size is analyzed. This paper provides a model-based approach for laser weld penetration monitoring instead of a pure empirical correlation between a measured signal (e.g., acoustic, infrared) and the penetration depth. Experiments were conducted to compare the depth estimation based on the model to bead-on-plate welds on low carbon steel plates of varying thickness at different laser power levels and speeds. It is shown that the temperature on the bottom surface is a consistent indicator of penetration depth and that the correlation is also sensitive to the sensor location as well as other process conditions such as weld shape, width, and the plate thickness. The proposed model is computationally efficient and is suitable for on-line process monitoring application.

Real-Time Weld Penetration Depth Monitoring With Laser Ultrasonic Sensing System

2005 ◽  
Vol 128 (1) ◽  
pp. 280-286 ◽  
Author(s):  
Bao Mi ◽  
Charles Ume
Keyword(s):  
Real Time ◽  
Penetration Depth ◽  
Weld Pool ◽  
Phased Array ◽  
Welding Process ◽  
Analytical Relationship ◽  
Correlation Technique ◽  
Weld Penetration ◽  
Weld Quality ◽  
Sensing System

A real-time ultrasound-based system for controlling robotic weld quality by monitoring the weld pool is presented. The weld penetration depth is one of the most important geometric parameters that define weld quality, hence, remains a key control quantity. The sensing system is based on using a laser phased array technique to generate focused and steered ultrasound, and an electromagnetic acoustic transducer (EMAT) as a receiver. When a pulsed laser beam is incident on the surface of a condensed matter, either the thermoelastic expansion or ablation induces mechanical vibrations that propagate as ultrasound within the specimen. Both the ultrasound generation by the laser phased array and the reception by the EMAT are noncontact, which eliminates the need for a couplant medium. They are capable of operating at high temperatures involved in the welding process. The ultrasound generated by the laser phased array propagates through the weld pool and is picked up by the EMAT receiver. A signal-processing algorithm based on a cross-correlation technique has been developed to estimate the time-of-flight (TOF) of the ultrasound. The relationship between the TOF and the penetration depth of the weld has been established experimentally and analytically. The analytical relationship between the TOF and the penetration depth, which is obtained by the ray-tracing algorithm and geometric analysis, agrees well with the experimental measurements.

A calibration tool for weld penetration depth estimation based on dimensional and thermal sensor fusion

2021 ◽  
Author(s):  
Aitor Zalakain-Azpiroz ◽  
Nieves Rodríguez ◽  
Aitor García de la Yedra ◽  
Joaquín Piccini ◽  
Xabier Angulo-Vinuesa
Keyword(s):  
Penetration Depth ◽  
Sensor Fusion ◽  
Depth Estimation ◽  
Thermal Sensor ◽  
Weld Penetration ◽  
Calibration Tool

Automated Deburring with a Filamentary Brush: Prescribed Burr Geometry

1999 ◽  
Vol 121 (3) ◽  
pp. 385-392 ◽  
Author(s):  
Robert J. Stango ◽  
Lienjing Chen ◽  
Vikram Cariapa
Keyword(s):  
Penetration Depth ◽  
Dynamic Model ◽  
Control Strategy ◽  
Feed Rate ◽  
Material Removal ◽  
Vision System ◽  
Closed Form Solution ◽  
Straight Edge ◽  
Finite Width ◽  
Production Environment

In this paper, a dynamic model for removal of edge burrs with a compliant brushing tool is reported. Description of the burr geometry is assumed to be known through on-line measurement methods such as a computer vision system in the flexible manufacturing cell. Dynamic response of the brush/workpiece system is evaluated on the basis of experimentally obtained data. Master Curves are introduced as machining descriptors which characterize the incremental burr removal performance of the brush/workpiece system, leading to the development of an analytical dynamic model for orthogonal burr removal using a finite-width brushing tool. Based upon the dynamic model for material removal, a control strategy for automatic deburring is presented for burr configurations having constant height as well as variable height. A closed-form solution for transverse brush feed rate is obtained which is applicable for removal of burrs having variable height, as described by suitable geometry functions. For illustrative purposes, simulations are carried out for a straight-edge burr profile and sinusoidal burr geometry. Results are reported which identify important relationships among brush feed rate, brush penetration depth, and brush rotational speed. In order to help assess the validity of the proposed analytical model and control strategy, experimental results are reported for a combination ramp/straight-edge burr configuration. The results demonstrate generally good correlation between the predicted and actual profile for the edge burr that has been machined. In addition, some important observations include; (1) burr removal is most rapidly carried out by using the highest brush speed and deepest brush/workpiece penetration depth, subject to the condition that the brush fiber is not damaged, (2) Currently available polymer abrasive brushing tools exhibit very slow machining characteristics and must be improved in order to be used in a production environment where burr size is appreciable, (3) Material removal characteristics of the leading and trailing edge of brushes may be a source of error which merits further investigation.

Monitoring of laser weld penetration using sensor fusion

2002 ◽  
Vol 14 (2) ◽  
pp. 114-121 ◽  
Author(s):  
Allen Sun ◽  
Elijah Kannatey-Asibu ◽  
Mark Gartner
Keyword(s):  
Sensor Fusion ◽  
Weld Penetration ◽  
Laser Weld

OCT-Einschweißtiefenüberwachung bei Unterdruck/OCT-based weld penetration monitoring at reduced ambient pressure – Influence of reduced ambient pressure on the OCT signal quality in laser deep penetration welding

2021 ◽  
Vol 111 (11-12) ◽  
pp. 863-868
Author(s):  
Thorsten Mattulat ◽  
Ronald Pordzik ◽  
Peer Woizeschke
Keyword(s):  
Penetration Depth ◽  
Ambient Pressure ◽  
Laser Beam Welding ◽  
In Situ Monitoring ◽  
Deep Penetration ◽  
Weld Penetration ◽  
Laser Deep Penetration Welding ◽  
Deep Penetration Welding ◽  
Non Destructive

Die optische Kohärenztomographie (OCT) erlaubt die zerstörungsfreie In-situ-Überwachung der Einschweißtiefe beim Laserstrahlschweißen. Für dieses Verfahren wird hier der Einfluss von verringerten Umgebungsdrücken auf die Messqualität untersucht. Es wird gezeigt, dass sich bei niedrigerem Umgebungsdruck deutlich größere Signalanteile aus dem Bereich des Bodens der Dampfkapillare zurückerhalten lassen. Auf diese Weise steigen die effektive Messfrequenz und die Erkennbarkeit von Änderungen der Einschweißtiefe.   Optical coherence tomography (OCT) enables non-destructive in-situ monitoring of the weld penetration depth during laser beam welding. For this technology, the influence of reduced ambient pressures on the measurement quality is investigated. It is shown that significantly larger signal components are obtained from the bottom of the vapor capillary at lower ambient pressure increasing the applicable measurement frequency and the detectability of changes in the weld penetration depth.

Estimation of Al/Cu laser weld penetration in photodiode signals using deep neural network classification

2021 ◽  
Vol 33 (4) ◽  
pp. 042009
Author(s):  
Kidong Lee ◽  
Sanghoon Kang ◽  
Minjung Kang ◽  
Sung Yi ◽  
Cheolhee Kim
Keyword(s):  
Neural Network ◽  
Deep Neural Network ◽  
Weld Penetration ◽  
Laser Weld ◽  
Neural Network Classification

scholarly journals Conditionals on crutches: Expanding the modal horizon

2020 ◽  
Author(s):  
Dario Paape ◽  
Malte Zimmermann
Keyword(s):  
Computational Modeling ◽  
Reaction Times ◽  
Process Models ◽  
Cognitive Mechanisms ◽  
Value Judgments ◽  
Value Judgment ◽  
Counterfactual Conditionals ◽  
Modeling Techniques ◽  
On Line ◽  
Truth Value

Using truth-value judgment tasks, we investigated the on-line processing of counterfactual conditionals such as "If kangaroos had no tails, they would topple over". Face-value plausibility of the counterfactual as well as the complexity of the antecedent were manipulated. Results show that readers' judgments deviate from face-value plausibility more often when the antecedent is complex, and when the counterfactual is plausible rather than implausible. We interpret our results based on the modal horizon assumption of von Fintel (2001) and argue that they are compatible with a variably strict semantics for counterfactuals (Lewis, 1973). We make use of computational modeling techniques to account for reaction times and truth-value judgments simultaneously, showing that implementing detailed process models deepens our understanding of the cognitive mechanisms triggered by linguistic stimuli.

Sign in / Sign up

Export Citation Format

Share Document