Aus der Ferne betrachtet – Prozessüberwachung beim Remote‐Laserstrahlfügen und ihre Möglichkeiten

Müller-Borhanian, Jürgen; Kogel‐Hollacher, Markus

doi:10.1002/latj.200790129

Cited by 1 publication

(1 citation statement)

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“…The upper parts sketch cross sections of the welding processes, the lower parts show thermal images acquired coaxially to the laser axis piece material. Therefore, perturbations such as the ejection of spatters can cause instabilities which result in weld seam defects such as craters, pores, seam under fill, bonding failure, or insufficient penetration depth [4].…”

Section: Introductionmentioning

confidence: 99%

The full penetration hole as a stochastic process: controlling penetration depth in keyhole laser-welding processes

Blug

Abt²,

Nicolosi³

et al. 2012

Appl. Phys. B

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Although laser-welding processes are frequently used in industrial production the quality control of these processes is not satisfactory yet. Until recently, the "full penetration hole" was presumed as an image feature which appears when the keyhole opens at the bottom of the work piece. Therefore it was used as an indicator for full penetration only. We used a novel camera based on "cellular neural networks" which enables measurements at frame rates up to 14 kHz. The results show that the occurrence of the full penetration hole can be described as a stochastic process. The probability to observe it increases near the full penetration state. In overlap joints, a very similar image feature appears when the penetration depth reaches the gap between the sheets. This stochastic process is exploited by a closedloop system which controls penetration depth near the bottom of the work piece ("full penetration") or near the gap in overlap joints ("partial penetration"). It guides the welding process at the minimum laser power necessary for the required penetration depth. As a result, defects like spatters are reduced considerably and the penetration depth becomes independent of process drifts such as feeding rate or pollution on protection glasses.

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Section: Introductionmentioning

confidence: 99%