The Analysis of Circular-Riveting the Laminated Cores in Stamping the Electrical Steel Plates

• Main Authors: HUANG,YUN-KUI, 黃筠貴
• Other Authors: LIN,HENG-SHENG
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/46266126846227246860

碩士 === 國立高雄應用科技大學 === 模具工程系 === 104 === The stators, rotators (both are generally called iron cores) and E1 iron cores are widely applied to the motors and the transformers of all sorts of products. The technique of circular lamination riveting is generally being used to manufacture iron cores. Riveting means making a bump on the electrical steel which is similar to punching but the material is not ruptured (the V shape riveting have part of rupture). Two electrical steels are fixed through interference fit of raised part and concave part. The quality of riveting directly affects the probability of dispersion. Dispersions refer to the failure of riveting between two electrical steels, and occur frequently in the process of the wire-wound or the vibration among products. Therefore, to improve the quality of riveting between two electrical steels is important for the yield rate and the electrical property of the product. The study discusses the relationship of riveting force in applying variant die clearances to electrical steels. Three different electrical steels of 0.5mm thickness, H470, H600 and H1300 respectively, and die clearances 1%, 2%, 3%, and 4% plate thickness are being used. DEFORM 2D is used to simulate the pre-forming of electrical plate (forming the bumps), define the depth formed and make the bumps rivet with each other. After that, exit the riveting bumps, make comparison between those riveting forces, and get the exit-load from different die clearness. The simulation shows that the depth of 0.43 mm is shaped when using H1300, followed by H600 depth of 0.412 mm and finally the H470 depth of 0.40 mm. Using 90% of depth limit as riveting safe depth to avoid bumps rupture. The result reveals that, both in simulation analysis and experiment of riveting force, the die of small die clearance create the best riveting force. On the contrary, the dies of big die clearance cause too much interference which results in severe deformation of convex part and concave part, and consequently, the riveting easily failed because of the phenomenon of self-loosening. According to the stress distribution and convex forming, riveting force is affected by the angle of sidewall deformation (taper angle), area of contact and the amount of compressive stress. Among all, the taper angle is the most influential. The taper angle disperses the compressive stress which not only reduces the normal compressive stress of sidewall but causes self-loosening, diminishing the effects of riveting. As a result, less interference (smaller die clearance) should be applied to round riveting die design.