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Hagen Kerl
| Title | A contribution to increasing the service life of electrode caps in resistance spot welding |
| ISBN | 978-3-8440-5690-7 |
| Type of publication | dissertation |
| Language | German, English |
| Pages | 154 pages |
| Illustrations | 97 illustrations |
| Format | 21 x 14.8 cm |
| price | 48,80 € / 61,10 SFr |
| Publication date | 2018 |
| Published by | Shaker Publishing House GmbH |
Summary
The work deals with the factors that reduce the tool life of electrode caps in resistance spot welding. With the increased use of different material grades in vehicle construction, increasing process costs arise for the joining process. Generally speaking, every type of sheet metal coating has an influence that reduces the amount of material required.
Common sheet metal coatings are zinc or aluminum-silicon coatings. These coatings and the sheet metal material itself react with the electrode cap during welding, which means that the electrode caps have to be re-milled and replaced more frequently. The wear of an electrode cap is made up of its enlarged working surface and the alloy formation with the sheet metal coating. Both increase the contact resistance of the electrode cap with the sheet metal surface. Suitable alloying concepts for the electrode caps are based on an increased hot hardness and the reduction of the diffusion quantity of foreign atoms. The investigations show that no cap material (CuCrZr1, CuAg0.1, Nitrode) is suitable for joining all sheet materials (HX340LAD+Z, 22MnB5+AlSi, AlMg3).
Furthermore, an analysis of the influence of various welding parameters is to be carried out, in particular with pulse welding, the discontinuous welding current feed. The interest lies in the change in the level when the welding parameters are varied. The analysis is carried out on single-cut and multi-cut asymmetrical sheet metal combinations.
The requirement to detect the welding lens growth non-destructively is realized by measuring the voltage drop between the joining sheets. The resistance curve can be used to determine when a weld lens first forms between which sheets.