TPT November 2013

Technology News

Weld seam detection on precision steel tubes with low error rate THE position of a weld seam has a crucial influence on the quality of the final product when bending or hydraulic forming a tube. An unfavourable seam position causes deviations in geometry, has influence on the firmness and in the life span of the produced component or precipitates by cracking during the manufacturing process. In order to prevent such disadvantages, different solutions for the localisation of the weld seam were established. Common optical procedures, such as colour marking of the longitudinal welds in order to detect their position, are widespread. Camera-based systems, which detect the visible welding seam are also in use. What to do, if colour marking is not possible or the welding seam is not visible? This problem arises when an application requires a treatment of the tube after welding, for example in the production of precision steel tubes. The cold drawing of the tubes changes the original surface and impedes the usage of colour. If the tube is additionally annealed, the welding seam may become invisible in its external appearance. At this point Roland Electronic offers alternative techniques, well known from the non-destructive testing of materials with eddy current, magnetic induction as well as the magnetic This technique is based on the crystalline modifications of the structure within the weld seam. In the process of welding ferromagnetic steel, martensitic crystals are formed within the range of the heat effect zone. Since martensitic crystals hardly occur in the unwelded structure, the welding seam is detected by the crystal structure modification. The weld seam detector SND40 supports these alternative techniques and offers high process reliability in practical usage. Tubes with scraped weld seam and calibrated diameter will reach in the first detection run ratios of 99.9 per cent. The error rates in detection with an SND40 system are between 0 and 100ppm. leakage flux method. All these techniques have the advantage of dry functioning and without significant radiation exposure.

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Messe Düsseldorf GmbH P.O. Box 101006 40001 Düsseldorf _ Germany

Tel. +49(0)211/4560-01 Fax +49(0)211/4560-668 www.messe-duesseldorf.de

Roland Electronic GmbH – Germany Website: www.roland-electronic.com

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N ovember 2013

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09.09.13 12:20