Jain Anil Kumar, Pandey Pulak M
Rocket Motor Fabrication Activities, Vikram Sarabhai Space Centre, Indian Space Research Organization, Trivandrum 695022, India.
Deptt. of Mech Engg, IIT Delhi, India.
Ultrasonics. 2017 May;77:1-16. doi: 10.1016/j.ultras.2017.01.015. Epub 2017 Jan 23.
Un-deformed chip thickness is a critical parameter in machining processes. Measuring un-deformed chip thickness experimentally is a complicated process, especially in micro machining and may not even be measured accurately. The un-deformed chip thickness has an influence on material removal rate, cutting forces, specific energy and surface finish etc. In ceramic machining, it is also an indication of material removal mode such as ductile or brittle fracture. In the present study, an effort is made to model undeformed chip thickness, cutting forces and specific cutting energy in rotary ultrasonic machining (RUM) applied to the side milling operation. RUM may be considered as super-imposition of ultrasonic vibrations on the grinding process. The kinematics of ultrasonic motion has been applied to the grinding for the development of the RUM process models. To validate the models, machining experiments have been performed on borosilicate glass in RUM and grinding modes. Percentage of ductile mode of fracture for the machined surfaces has been evaluated using SEM images. Surface roughness values have also been compared for the same material removal rate conditions to ascertain fracture mode. Developed models have been verified and found that ductile mode of fracture as well as surface finish were higher in RUM as compared to grinding process for same material removal rate. RUM process for six aerospace grade materials has also been tried using micro and macro tools and size effects studied.
未变形切屑厚度是加工过程中的一个关键参数。通过实验测量未变形切屑厚度是一个复杂的过程，尤其是在微加工中，甚至可能无法准确测量。未变形切屑厚度会对材料去除率、切削力、比能和表面光洁度等产生影响。在陶瓷加工中，它还可指示材料去除模式，如延性或脆性断裂。在本研究中，致力于对旋转超声加工（RUM）侧面铣削操作中的未变形切屑厚度、切削力和比切削能进行建模。旋转超声加工可被视为超声振动叠加在磨削过程上。超声运动学已应用于磨削，以开发旋转超声加工过程模型。为了验证模型，在旋转超声加工和磨削模式下对硼硅酸盐玻璃进行了加工实验。使用扫描电子显微镜图像评估加工表面的延性断裂百分比。在相同材料去除率条件下，还比较了表面粗糙度值以确定断裂模式。已验证所开发的模型，发现在相同材料去除率下，与磨削过程相比，旋转超声加工中的延性断裂模式以及表面光洁度更高。还使用微型和宏观刀具对六种航空航天级材料进行了旋转超声加工，并研究了尺寸效应。
