ABSTRACT

The surface roughness required for the optical application and lenses is in the range of nanometers possible to achieve in single-point diamond turning (SPDT). The machining parameters like feed, spindle speed, tool nose radius, and depth of cut influence the surface roughness. These parameters, along with tool-workpiece interaction, develop vibration, and this vibration deteriorates the surface roughness. Three different vibrations as feed, cutting, and infeed act on the tool in three directions: X, Y, and Z. In this study, the impact of these three-direction vibrations is studied on the polymethylmethacrylate (PMMA). The infeed vibration is creating a ‘tool jump,’ leaving the material left uncut below it. This uncut material is responsible for the variation in surface roughness. The Taguchi’s L₁₈ orthogonal array is used for experimentation, and the three-axis accelerometer is used to measure the tool vibrations during machining. Grey relational analysis is applied to find out the optimum parameters for lower surface finish and low vibration responses. A mathematical regression model has been developed, followed by a confirmation test to verify the experimental responses. The surface roughness (S_a) 25.9 nm is formed by utilizing optimized parameters. This study is beneficial for optical industries manufacturing, e.g., Intra-ocular lenses, Spectacle lenses, ophthalmic lenses, by providing optimum processing conditions.

摘要

光学应用和透镜所需的表面粗糙度在纳米范围内，可以在单点金刚石车削 (SPDT) 中实现。进给、主轴转速、刀尖半径和切削深度等加工参数会影响表面粗糙度。这些参数以及工具与工件的相互作用会产生振动，并且这种振动会降低表面粗糙度。进给、切削和进给三种不同的振动在三个方向上作用于刀具：X、Y 和 Z。在本研究中，研究了这三个方向的振动对聚甲基丙烯酸甲酯 (PMMA) 的影响。进给振动会产生“刀具跳跃”，使材料在其下方未切割。这种未切割的材料是造成表面粗糙度变化的原因。田口的 L ₁₈正交阵列用于实验，三轴加速度计用于测量加工过程中的刀具振动。应用灰色关联分析来找出低表面光洁度和低振动响应的最佳参数。已经开发了一个数学回归模型，然后进行了确认测试以验证实验响应。利用优化的参数形成25.9 nm的表面粗糙度( S _{a )。}这项研究通过提供最佳加工条件，有利于光学工业制造，例如人工晶状体、眼镜片、眼科镜片。