TPT July 2012

Technology News

HFI/HFC longitudinal seam welding of tubular sections

circuit against deformed tubes (risk of being dragged along) and simplify safe inductor changes. If impeders cannot be used in individual sections due to a lack of space, a separate contact unit makes it easy to change from induction welding to contact welding with automatic contact adjustment and wear indication. Contact wear is monitored and compensated by position encoders. Extensive process expertise gained from using EloWeld TM HF generators with virtually all high-frequency weldable materials and tube sections over several decades enables users to produce perfect welds thanks to fully reproducible frequencies matched to production processes and defined welding energy. SMS Elotherm supports customers with the services of experienced commissioning specialists.

of all, material yield is improved through precise cutting of the non-compliant tube ends rather than always cutting fixed crop lengths, thereby leaving the maximum possible prime length. Given the non-compliant tube ends will vary in length and the possibility for special fault areas that must also be removed, the resulting prime tubes will vary in length. In this case, unnecessary material losses will be avoided by optimising the actual prime length against the customer order log. In essence, the actual prime lengths, after testing, are best fit to the customer order log so multiple orders can be accumulated simultaneously thereby limiting material loss and optimising yield.” By integrating the new cutting equipment, the customer will reduce non-value added transportation and enable post inspection re-working without sorting. In addition, untested To reduce service costs, easily replaceable standard modules with a single Mosfet or IGBT are used instead of expensive power units in the form of compact modules with many transistors. The digitally configurable converter features modern diagnostics and visualisation with online status and fault indications in plain text. Separation of the converter from the external resonant circuit offers additional decisive advantages. The external resonant circuit contains no unprotected electronic power units liable to cause problems due to vibration and moisture. There are no sensitive components, such as transistors or driver boards, in the direct vicinity of the welding line. They are located in the converter cabinet behind the line or in a central control room for easy servicing. The HF output transformer is designed as an isolating transformer, and pneumatic inductor clamps protect the external resonant

THE first result of this year’s Tube Show in Düsseldorf was a big order received by Reika fromVallourec &Mannesmann, a global leader in the tube industry. The company ordered two cut-off machines for optimised end cutting of tubes after ultrasonic testing. The new cut-off equipment will enable fully automatic cutting of untested ends anddefect zonesafter tubeshavepassed through an integrated phased array testing system (an advanced method of ultrasonic examination). “This will give the possibility to separate untested or defective tube ends and samples, in a given cycle time, after the phased-array test,” says Reika managing director Hans-Jörg Braun. The cutting machines including conveyors will be integrated in the existing material flow. “With our cutting machines, several improvements can be achieved with a single stroke,” Mr Braun added. “First ELOTHERM claims to be the only manufacturer to offer customers both constant-current and constant-voltage high-frequency welding generators. Constant-current welders using a parallel resonant circuit with Mosfet transistors are designed for welding powers up to 800kW and frequencies from 100 to 600kHz. The EloWeld TM constant-voltage HF generator with a series resonant circuit and IGBT transistor modules, introduced by Elotherm in the mid-1990s, offers welding power up to 2,000kW. Both EloWeld TM systems feature convenient and reliable load adaptation using reproducible capacitor switching with pneumatic switches, either manually or automatically from the control cabinet. A drawback of variable frequency adjustment, eg retuning the resonant circuit for different jobs, is the need for readjustment to restore the original frequency, voltage and current settings, which may be very time-consuming.

SMS Elotherm GmbH – Germany Website: www.sms-elotherm.de

Cut-off machines for optimised end cutting into finishing lines

ends could be separated and sampled easily, leading to an additional run-time optimisation of the tested products. Clean cuts are guaranteed on all cutting machines delivered by the Hagen company, equipped with carbide cutting tools – perpendicular and parallel, so there will be no damage on the surface, Mr Braun said. “High tool life is reducing also the tooling cost, whereas the high speed rotating cut-off head and large tool feed lead to reduction of cutting time. Short idle times and total cycle times increase productivity.” Since processing is done cleanly and dry without coolant lubricants, there is no need for another finishing step. Hans- Jörg Braun concluded: “Simple but effective – just like all our machines.” Reika GmbH & Co KG – Germany Email: sabine.gerstkamp@reika.de Website: www.reika.de

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J uly 2012