A friction stir welding equipment with high rotation speed and constant load is successfully developed in this study to weld the multi-laminated silicon steel sheets widely used on regular transformers. This equipment consists of a spinning unit, a loading unit, and a feeding unit. A WC round rod with 3 mm diameter is used as welding tool. Under different operating conditions, such as the normal load(140~480 N), the spindle speed (12000~24000rpm), the feeding rate (0~1.58 mm/s), the welding characteristics and the welding mechanism of multi-laminated silicon steel sheets, and the welding feasibility of the transformer are investigated.
Firstly, the contour map of welding depth in terms of spindle speed,normal load, and depth of point welding is established for dwell welding time 15 seconds.
Secondly, based on this contour map, two experimental conditions of the long-pass welding tests are selected to investigate the effect of normal load (Fd), the spindle speed (Ns), and the feeding rate (f) on the failure load of weld under the shear. According to the experimental results, the empirical formula is obtained as Ff =40.6(Fd¡DNs)1.123(f)-0.791. In this formula,(Fd¡DNs)1.123(f)-0.791 is proportional to the frictional work per unit moving distance. With the larger frictional work, this represents the heat generation of the workpiece material is higher with more uniform friction stir, so that the bonding strength of the material increases and the failure load of weld is larger.
According to the micrograph observations, the thermo-mechanically affected zone is significantly influenced by high heat action generated from the friction between the tool and the weld surface region, so that the plastic flow of the workpiece material occurs to cause the multi-laminated silicon steel sheets bonding together.
Finally, the transformer is successfully welded under the experimental conditions of the long-pass welding tests with the smaller welding depth and the better failure load.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0822111-173106 |
| Date | 22 August 2011 |
| Creators | Lin, Jia-Shiang |
| Contributors | Kuo-Chen Huang, Rong-Tsong Lee, Chung-Ming Lin, Yuang-Cherng Chiou |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0822111-173106 |
| Rights | user_define, Copyright information available at source archive |
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