1、毕 业 设 计（论 文）外 文 参 考 资 料 及 译 文译文题目： Built-up Edge Investigation Invibration Drilling of Al2024-t6对铝2024-T6钻削积屑瘤研究 学生姓名： 学 号： 专 业： 所在学院： 指导教师： 职 称： 20xx年 2月 27日 Built-up Edge Investigation in Vibration Drilling of Al2024-T6abstractAdding ultrasonic vibrations to drilling process results in an advanced
2、 hybrid machining process, entitled vibration drilling. This study presents the design and fabrication of a vibration drilling tool by which both rotary and vibrating motions are applied to drill simultaneously. High frequency and low amplitude vibrations were generated by an ultrasonic transducer w
3、ith frequency of 19.65 kHz. Ultrasonic transducer was controlled by a MPI ultrasonic generator with 3 kW power. The drilling tool and workpiece material were HSS two-ute twist drill and Al2024-T6, respectively. The aim of this study was investigating on the effect of ultrasonic vibrations on built-u
4、p edge, surface quality, chip morphology and wear mechanisms of drill edges. Therefore, these factors were studied in both vibration and ordinary drilling. Based on the achieved results, vibration drilling offers less built-up edge and better surface quality com- pared to ordinary drilling.Keywords:
5、 Vibration drilling、Drilling、Ultrasonic、Aluminum 2024-T61. IntroductionDrilling processes constitute a big part of all machining processes (about 40%) 1, which may have a great effect on production costs. A strategy that can reduce these costs is optimizing these processes. A recent method used to i
6、mprove twist drilling process is adding ultrasonic vibrations to the process. In this method, ultrasonic vibrations are used to improve Ordinary Drilling (OD). This kind of drilling process, that is a hybrid process, is entitled Vibration Drilling (VD) in this paper. In VD the high frequency and low
7、 amplitude vibrations are added to OD in direction of feed. Hence, the drill bit has an additional ultrasonic reciprocating motion in the longitudinal direction. Different investigators have reported a variety of improvements in using VD. Babitsky et al. 2 showed that it is possible to drill through
8、 thin, exible plates with little deformation by VD in contrast to OD where a back support needed to hold plates against thrust force. They explained that the reduction of deformation of plates in VD is because of a discon- tinuous cutting phenomenon which decreases thrust force. Pujana et al. 3 repo
9、rted that in VD of Ti6Al4 V, chips intend to break. Azarhoushang and Akbari 4 studied the drilling of Inconel 738- LC. They found that the surface quality improves in VD when compared to OD. Other researchers who applied ultrasonic vibrations to machining processes declared that thrust force and tor
10、que decreased by these processes 59. Li etal. 10 developed multi-stage control for vibration condition of VD in order to optimize drilling of laminated composite materials. They changed the vibration condition according to the workpiece material being cut and the cutting situation (entrance, middle
11、and exit of the hole). By this technique, the average deection of drill point, error of the hole diameter and the exit burr height were reduced by over 20%, 80% and 40%, respectively, in contrast to OD. Liao et al. 11 investigated the VD of Inconel 718. The reduction of chips length and torque varia
12、tions in VD were reported in comparison to OD. Zhang et al. 12 showed that in micro VD in compared with micro OD, tool life increases. They also demonstrated that in VD, because of the drill skidding reduction, hole dimensional accuracy can be improved. Chen et al. 13 developed a voltage controller
13、to keep resonance condition during VD. The reported results showed that by this technique tool life in VD of Inconel 718 enhanced when compared to OD. However, against all mentioned benets for VD, there are some unexpected results. For example, reduction of tool life has been reported in some resear
14、ches 14,15. The present researchers believe that much more studies need to be done to know VD. To do this, some drilling experiments performed on Al2024-T6. Use of aluminum alloys in industry is growing because they are lightweight metallic materials and have different interesting mechanical and the
15、rmal properties 16. But, in dry machining of these alloys, the major problems are built-up edge formation and low quality of generated surface 1620. These problems are more critical in producing of precision workpieces. In this work, built-up edge in VD of Al2024-T6 is studied in detail. Also, the effect of VD on surface quality is investigated and compared to OD. The inuence of machining condition and built-up edge on chip morphology is also presented.2. Vibration drillingFig. 1 shows a schematic conguration of 1D vibration dr
