Effect of weld tip geometry on ultrasonic welding of A6061 aluminum alloy

Transcription

1 [ 27 p (2009)] ** *** ** Effect of weld tip geometry on ultrasonic welding of A6061 aluminum alloy by WATANABE takehiko, MIYAJIMA Daisuke and YANAGISAWA Atsushi Authors ultrasonically welded A6061 aluminum alloy sheet using two types of weld tips with the different contact face geometry, and investigated the effect of the weld tip on the performance and interface structure of the welds. One type of tip has a cylindrical contact face without knurl, which is called C-tip in this study. The other type of tip has flat contact face with knurl, which is called K-tip in this study. The following main results were obtained. The strength of the joints welded using C-tip was higher than that welded using K-tip and the fluctuation in joint strength with C-tip was smaller. The C-tip could stably produce the higher strength joint. Using K-tip, the knurl indentations were made on the workpiece surface due to the pyramidal projections on the weld tip, and the indentation size expanded with welding time, resulted in the deterioration of the joint property. On the other hand, the indentation made on a workpiece surface by using C-tip showed a distinctive shape like an ellipse elongated perpendicular to the ultrasonic vibration, and the indentation grew with welding time. Using K-tip, unbonded regions remained at the weld interface due to the concave on the weld tip face. In the cross-sectional structure parallel to the workpiece width of the joint welded using C-type of tip, the distinctive feature was observed that the faying surface of the anvil workpiece was mixed with that of the sonotrode workpiece by intense plastic deformation and a horn-like protuberance intruding into the sonotrode workpiece was formed at the periphery of the welded area. Key Words: Ultrasonic welding, Tip geometry, Cylindrical tip, Knurled tip, Aluminum alloy sheet, Joint strength, Interfacial structure 1. 1) 6000 A6061 2) 0.8 mm * ** Member, Niigata University, Graduate School *** Student Member, Niigata University, Graduate School 3) 4 5) 2. 1mm A6061 T6 Al Mg Si 302 MPa 110 HV Al 2 A6061 T6 100 mm 10 mm 10.5 mm Ra= 0.42 m W 15 khz 53 m peak to peak

2 8 A mm 10 mm 10 mm 10 mm 0.8 mm 0.3 mm 90 Knurled 200 mm Curved K C Fig. 1 Fig mm Al 10.0 mm Al Fig. 2 U SEM EDS C 1.0 s 588 N 882 N 1176 N 1470 N 6) Fig. 3 K 1470 N 588 N 882 N 1176 N C K K C 1176 N 1470 N C K Al 3.2 K C K Fig. 2 Schematic of the preparation of tensile test specimen. Fig. 1 Schematic of the apparatus for ultrasonic welding and the combinations between horn side tip and anvil side tip. Fig. 3 Relation between clamping force and tensile load of joints welded using K-tip and C-tip.

3 N 0.5 s 1.0 s 1.5 s 2.0 s 2.5 s 3.0 s Fig. 4 K 2.0 s C 2.0 s 1171 N 3.0 s Al 1.0 s 2.0 s 2.5 s K C C C 558 N 1470 N 0.5 s 3.0 s Fig N 1.5 s 1300 N 3.3 K C Al Fig N K Al Fig. 7 W1 W2 K C Fig s 3.4 K C SEM Fig N Fig. 8 K 1) Fig. 4 Relation between welding time and tensile load of joints welded using K-tip and C-tip. Fig. 6 Surface appearances of the horn-side workpiece scratched by K-tip and C-tip. Fig. 5 Relation between welding time, clamping force and tensile load of joints using C-tip. Fig. 7 Appearance of indentation produced by K-tip and relation between indentation size and welding time.

4 10 A6061 Fig. 10 Cross-sectional images parallel to the workpiece width of joint interface welded using K-tip. Fig. 8 Fracture surfaces of joints welded using K-tip at welding times of 0.5s to 1.5s. Fig. 11 Cross-sectional images parallel to the workpiece width of joint interface welded using C-tip. Fig. 9 Fracture surfaces of joints welded using C-tip at welding times of 0.5s and 1.0s. 1.0 s E S D E S D 1) Fig. 9 C 0.5 s SEM S D 1.0 s SEM S D N 0.5 s, 1.0 s, 1.5 s K C Fig. 10 Fig. 11 Fig. 10 K 0.5 s 1.5 s 0.5 s 1.5 s 1) Fig. 11 C 0.5 s 1.0 s 0.8 s 1.2 s

5 s Fig. 9 7) 8) m C 1176 N 1.0 s Fig. 12 Fig. 13 Fig. 14 SEM (a) (b) SEM 4. K C K C K C C Fig. 12 Behavior of thick oxide film on the faying surface of anvil side workpiece after welding using C-tip. Fig. 13 Behavior of thick oxide film on the faying surface of horn side workpiece after welding using C-tip. Fig. 14 SEM photograph of fracture surface of horn side specimen with thick oxide film welded under 1176N clamping force and 1.0s welding time.

6 12 A6061 Fig. 15 Schematic representations for the bonding processes in ultrasonic welding using K-tip and C-tip. K C Fig. 15 (a) (b) (a) K 7) (b) C 6) 5. C K A C K 2 K Al C 3 K C 1) WATANABE Takehiko, ITOH Hajime, et al: Ultrasonic Welding of Heat Treatable Aluminum Alloy A6061 Sheet, Quarterly Journal of Japan Welding Society, Vol.26 No.2 (2008), pp (in Japanese) 2) Edited by R. L. O Brien: Welding Handbook 8 th Edit, AWS, 1991, pp ) R. JAHN, R. COOPER and D. WILKOSZ: The effect of Anvil Geometry and Welding Energy on Microstructures in Ultrasonic Spot Welds of AA6111-T4, Metallurgical and Materials Transactions A, Vol. 38A, No. 3 (2007), ) Minoru Okada and Sigeo Shin: Study on Ultrasonic Welding (1 st Report), J. of JWS, Vol.32, No.1 (1963), pp (in Japanese) 5) Fujio Tomiyasu and Kenji Takahashi: Ultrasonic Welding, J of JWS, Vol.32, No.4 (1963), pp (in Japanese) 6) L. A. GALIN (Translated by T. SATO): Elastic contact theory, Gendaikougakusha, 1974, pp.46. (in Japanese) 7) U. I. CHANG and J. FRISCH: On Optimization of Some Parameters in Ultrasonic Metal Welding, Welding Journal, Vol.53, No.1 (1974), 24S-35S. 8) Yasuo TAKAHASHI, Takamasa KAMEDA, et al: Numarical Study of Interfacial Deformation during Thermosonic Micro-bonding, Proc. of 9 th Symposium on Microjoining and Assembly Technology in Electronics 2003, pp (in Japanese)