TPT January 2014

Technology News

Weld seam detection on precision steel

tubes THE position of a weld seam has a crucial influence on the qual- ity of the final product when bending or hydraulic forming a tube. An unfavourable

seam position causes deviations in geom- etry, 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 that detect the visible welding seam are also in use. However, colour marking is not always possible, or the welding seam may not be 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 use of colour. If the tube is additionally annealed, the welding seam may become invisible in its external appearance. Roland Electronic offers alternative techniques, well known from the non-destructive testing of materials with eddy current, magnetic induction and the magnetic leakage flux method. These techniques have the advantage of dry functioning, without significant radiation exposure. Crystalline modifications of the structure within the weld seam can be used for detection. 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 SND40 weld seam detector supports these alternative techniques and offers high process reliability in practical usage. Roland Electronic claims that tubes with scraped weld seam and calibrated diameter will reach in the first detection run ratios of 99.9 per cent, and that the error rates in detection with an SND40 system are between 0 and 100ppm. Roland Electronic’s SND40 weld seam detector

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A M E M B E R O F T H E

G R O U P

W W W . Y O D E R M F G . C O M S A L E S @ F O R M T E K G R O U P. C O M PH: +1 216-292-4460 | FAX: +1 216-292-2898

Roland Electronic GmbH – Germany Fax: +49 7236 9392 33 Email: info@roland-electronic.com Website: www.roland-electronic.com

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J anuary 2014