The increased use of high-strength steels and new coatings for automotive components require different approaches and new technologies within all areas of manufacturing. The need for new approaches is also recognized for resistance welding. The new generation of servo weld guns presents clear advantages over the pneumatic weld guns. They allow high rates of motion with low-impact contact, short force build-up as well as reproducible electrode forces. Independent programmability of the servo axis opens unrestricted flexibility in controlling the opening stroke and 'instantaneous' modification of the welding force. The consistent use of electro-mechanical drives enables the monitoring and adaptive control of electrode force, electrode movement, equalizing force, and equalizing movement during the welding process. The fusion of the medium-frequency direct current (MFDC) welding controller and the servo drive control into one single weld technology controller produces shorter reaction times and allows adaptive control of both welding current and electrode force. It operates independent of the gun position and can compensate the respective position influences. Gaps between advanced high-strength steel (AHSS) sheets present a special 'challenge' to adaptive controllers for resistance welding. The variation of the spring-back rates and the hardening caused by stamping results in bigger component tolerances and lead to larger gaps. The consistent use of electro-mechanical drives enables the detection and compensation of gaps by adjusting the electrode force to the needed value. With the analysis of the recorded welding data, critical weld spots can be identified and selective measures can be implemented. Servo welding guns with electric motors open up new, extensive possibilities for the quality assurance and documentation concerning resistance welding. The weld technology controller may use in addition to the signal curves of welding current and electrode voltage the force and movement curves of the electrodes as well as the gun equalizing signals. This offers extensive possibilities not only for the adaptive process control, but also for the monitoring and supervision in quality control.
Servo gun controls for AHSS steels
Sheet Metal Welding Conference, 12 ; 6/3-6/10
2006
10 Seiten, 10 Bilder, 2 Quellen
Conference paper
English
Widerstandsschweißen , Fahrzeugbauteil , Servoregler , Elektrodenkraft , Flexibilität , Fertigungsüberwachung , elektromechanischer Antrieb , Monitoring , Bewegungssteuerung , Reaktionszeit , Adaptivregelung , Spalt , Auffederung , Aushärten (Metall) , elektrischer Strom , elektrische Spannung , Qualitätskontrolle , Prozesskontrolle
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