Research on ultrasonic-assisted drilling in micro-hole machining of the DD6 superalloy
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Research on ultrasonic-assisted drilling in micro-hole machining of the DD6 superalloy Xiao-Xiang Zhu1 • Wen-Hu Wang1 • Rui-Song Jiang2 • Zhan-Fei Zhang1 Bo Huang1 • Xiu-Wei Ma1
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Received: 13 October 2019 / Revised: 7 December 2019 / Accepted: 25 March 2020 Ó Shanghai University and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The DD6 nickel-based superalloy exhibits remarkably high temperature properties; therefore, it is employed as a crucial structural material in the aviation industry. Nevertheless, this material is difficult to process. Ultrasonic-assisted drilling (UAD) combines the characteristics of vibration processing technology and conventional drilling technology, significantly improving the machinability of difficult-to-machine materials. Thus, UAD experiments were performed on micro-hole machining of DD6 superalloy in this study. The effects of amplitude, frequency, spindle speed, and feed rate on thrust force, machining quality, and drill bit wear were studied; thereafter, a comparison was drawn between these effects and those of conventional drilling (CD). The experimental results reveal that the thrust force decreases with an increase in spindle speed or a decrease in feed rate for both UAD and CD. UAD can significantly reduce the thrust force. With the same processing parameters, the greater the amplitude, the greater the reduction of the thrust force. The surface roughness of the hole wall produced by UAD is lower than that of CD. Compared with CD, UAD reduces the burr height, improves machining accuracy, and reduces drill bit wear. Keywords Ultrasonic assisted drilling (UAD) Thrust force Machining quality Drill bit wear
& Rui-Song Jiang [email protected] 1
School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an 710072, People’s Republic of China
2
School of Aeronautics and Astronautics, Sichuan University, Chengdu 610065, People’s Republic of China
1 Introduction DD6 superalloy is a second generation nickel-based single crystal superalloy, exhibiting remarkably high temperature characteristics; it is a critical material that is used to manufacture turbine blades. Turbine blades operating at high temperature and under high pressure require film cooling to down-regulate surface temperatures to extend their service lives [1, 2]. The major existing processing methods for film cooling holes are conventional nanosecond laser processing and electrical discharge machining (EDM) [3–6]. EDM can only be used to process conductive materials; furthermore, it has a low processing efficiency, and fabrication and maintenance of its electrodes are difficult [7]. Compared with EDM, conventional nanosecond laser drilling is more efficient and capable of processing holes with complicated shapes at lower costs. However, like EDM, nanosecond laser drilling can also result in microcracks and a recasting layer. Accordingly, novel methods of film cooling hole processing should be explored. Ultrasonic-assisted drilling (UAD) is a novel technique that uses a ax
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