Restoration and Enhancement of X-Ray Images of Molten Pool during Laser Deep Penetration Welding

2012 ◽  
Vol 201-202 ◽  
pp. 356-359
Author(s):  
Jun Bin Xiang ◽  
Xiang Dong Gao
Keyword(s):  
Molten Pool ◽  
High Speed ◽  
Blind Deconvolution ◽  
Welding Process ◽  
304 Stainless Steel ◽  
Deep Penetration ◽  
X Ray ◽  
Laser Deep Penetration Welding ◽  
Contrast Stretching ◽  
Deep Penetration Welding

Owing to a strong capability of penetration, the radiography can be used to observe and analyze the formation of a molten pool inside weldments during laser deep penetration welding. The shape of a molten pool and the thermal transmit of laser through keyhole can be monitored and analyzed in real-time. During a high-power fiber laser bead on plate welding of Type 304 stainless steel, a high-speed radiography camera was employed to capture the molten pool images. These captured X-ray images were degraded by the disturbance and noises from the welding process and radiography devices. This paper proposes an efficient arithmetic to restore and enhance the X-ray images of molten pools. The point spread function (PSF) of X-ray image degeneration was obtained through blind deconvolution, And the PSF was applied as a parameter to implement the constrained least squares filtering of X-ray image of a molten pool. Also, the X-ray image was enhanced by contrast stretching transformation. Experimental results showed that the proposed arithmetic of image restoration and enhancement could improve the quality of X-ray images efficiently and protrude the contour feature of a molten pool.

Spatters during Laser Deep Penetration Welding with a Bifocal Optic

2016 ◽  
Vol 1140 ◽  
pp. 123-129 ◽  
Author(s):  
Joerg Volpp ◽  
Jennifer Srowig ◽  
Frank Vollertsen
Keyword(s):  
Energy Efficient ◽  
High Speed ◽  
Stable Process ◽  
Welding Process ◽  
Industrial Applications ◽  
Deep Penetration ◽  
Laser Deep Penetration Welding ◽  
Deep Penetration Welding ◽  
Processing Steps ◽  
Weld Seams

The energy efficient, high-speed laser deep penetration welding process is a technology which is increasingly used for industrial applications. In order to guarantee weld seams of high quality a stable process needs to be established. Especially when welding aluminium alloys the weld quality is reduced due to occurring spatters which entails a loss of material. Solidified spatters remain on the surface of the specimen after welding and need to be cleaned for further processing steps. One method to change the process behaviour is beam shaping. In this work, a bifocal optic is used to produce two foci along the beam axis in order to manipulate the energy input into the keyhole. Bead-on-plate welds are produced in aluminium alloy EN AW-6082 and mild steel S235. For comparison, welding is conducted using standard optics. The spatter occurrence is compared when using these different beam shapes. While a reduced number of spatters per time are observed the spatter size increases when using the bifocal optic in this study.

Simulation of Three-Dimensional Transient Behavior of Molten Pool in Laser Deep Penetration Welding

2016 ◽  
Vol 43 (11) ◽  
pp. 1102004
Author(s):  
夏胜全 Xia Shengquan ◽  
何建军 He Jianjun ◽  
王 巍 Wang Wei ◽  
吕学超 Lü Xuechao ◽  
张彤燕 Zhang Tongyan
Keyword(s):  
Molten Pool ◽  
Three Dimensional ◽  
Transient Behavior ◽  
Deep Penetration ◽  
Laser Deep Penetration Welding ◽  
Deep Penetration Welding

Numerical Simulation of Temperature Field during Laser Deep Penetration Welding

2011 ◽  
Vol 675-677 ◽  
pp. 865-867
Author(s):  
Ren Ping Wang ◽  
Y.P. Lei
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Computational Analysis ◽  
Energy Equation ◽  
304 Stainless Steel ◽  
Deep Penetration ◽  
Governing Equations ◽  
Laser Deep Penetration Welding ◽  
Deep Penetration Welding ◽  
Laser Keyhole Welding

A computational analysis is achieved during laser deep penetration welding. Multiple reflection and absorption are implemented simultaneously with the ray tracing technique in the keyhole. With all the governing equations including continuity, momentum and energy equation, the VOF method is adopted to trace the free surface of the molten pool. Temperature field is achieved by numerical simulation. The laser keyhole welding experiments on 304 stainless steel sheet showed that the computational results agree well with experimental results.

scholarly journals Experimental analysis of key parameters of laser fion welding of honeycomb plate heat exchanger

2019 ◽  
Vol 23 (5 Part A) ◽  
pp. 2757-2764
Author(s):  
Xinwu Du ◽  
Xin Jin ◽  
Huangzhen Lv ◽  
Shiguang Wang
Keyword(s):  
Heat Exchanger ◽  
Welding Process ◽  
Plate Heat Exchanger ◽  
Deep Penetration ◽  
Optimal Arrangement ◽  
Weld Shape ◽  
Plate Heat ◽  
Laser Deep Penetration Welding ◽  
Deep Penetration Welding ◽  
Hydraulic Bulging

The combination of laser deep penetration welding and hydraulic bulging is the most advanced production technology of honeycomb plate heat exchanger in the world. The micro-shape and heat transfer effect of the heat exchanger of honeycomb plate are mainly determined by the distribution mode of welding spot, weld shape and welding point arrangement. Therefore, the important principle of the honeycomb plate heat exchanger processing is to improve the pressure as much as possible to form turbulence while ensuring the welding quality. In the present experimental work, the effect of different weld shape and weld distribution of honeycomb plate heat exchanger produced by 06cr19n10 plate using hydraulic bulging and laser deep penetration welding on hydraulic bulging effect was studied carefully. The results showed that the optimal arrangement method is the equilateral triangle. The welding process parameters were optimized to increase the welding strength. The results showed that when the welding power was 2.1 kW, the bonding strength of the weld was the highest, at 52.70 kN. When the welding power was 2.2 kW and the gap between the welding points was 30 mm, the tensile strength of the honeycomb plate was the best, at 19.0 MPa. The results of this paper provide experimental support for industrial production of honeycomb plate heat exchanger.

scholarly journals Influence of Magnesium on Spatter Behavior in Laser Deep Penetration Welding of Aluminum Alloys

2019 ◽  
Vol 3 (3) ◽  
pp. 71
Author(s):  
Felsing ◽  
Woizeschke
Keyword(s):  
Aluminum Alloys ◽  
High Speed ◽  
Pure Aluminum ◽  
Welding Process ◽  
Magnesium Content ◽  
Flight Path ◽  
Deep Penetration ◽  
Camera System ◽  
Flight Path Angle ◽  
Deep Penetration Welding

The quality of welds, as well as the necessity of post-processing, is challenged by spatter generation during the laser keyhole welding process. In this study, the influence of the magnesium content on spatter behavior is studied for three aluminum alloys (Al99.5, AlMg3, and AlMg5). A synchronized dual high-speed camera system is used to observe the spatter behavior and to reconstruct 3D spatter trajectories as well as determine the characteristics of spatter velocity, flight path angle, and approximate spatter size. The mean spatter velocities and flight path angles of the welding experiments with the three alloys were in welding direction between 4.1 m/s and 4.6 m/s and 44.8° and 51.0°, respectively. Furthermore, the AlMg alloys show excessive spatter behavior with spray events of more than 50 spatters at a time, and less frequently spatter explosions. Spatter spray events show a character similar to spatter explosions. Volumetric evaporation is proposed as effecting these events. In contrast, and resulting from a different mechanism, pure aluminum (Al99.5) shows group ejection events with at least 10 spatters at a time. In this study, there are no correlations between spatter velocities and flight path angles, nor between velocities and approximate spatter sizes.

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.

Sign in / Sign up

Export Citation Format

Share Document