Ultra-precision motion systems

在今天的市场上，许多消费品，如隐形眼镜，DVD读/写头，以及几乎每台笔记本电脑屏幕上的增光膜，都是通过一种称为金刚石车削的技术制造的。 在这个过程中，一块形状良好的金刚石工具被安装在精密车床上，这样金属零件就可以加工出光学质量的表面。 这些零件然后被用作模具，以非常经济和精确的方式复制上述产品。 然而，在传统的金刚石车削工艺中，由于金刚石刀具不能响应快速旋转的主轴，可生产的表面限于几种类型的旋转对称表面。 因此，许多精心设计的和非常需要的光学表面，如微透镜阵列中使用的那些，不能以令人满意的精度制造。提出的研究是设计一种快速刀具伺服，它可以产生非常快的运动在2000倍的重力加速度。 当与精密车床结合使用时，快速刀具伺服系统在每次主轴旋转中将金刚石刀具移入和移出1000多次，从而可以生成非旋转对称表面。 我们还将设计和建造一个精密主轴，该主轴由一种新型的紧凑型电磁致动器引导、悬浮和驱动。 该执行器可根据精密主轴位置传感器的反馈信号自动调节主轴上的力。 因此，主轴运动误差可以减小到小于3纳米。该研究成果将显著提高数字投影机镜头、数码相机镜头等产品自由曲面的制造效率和精度。

In today's market, many consumer products, such as contact lenses, DVD read/write heads, and the light-enhancing films on almost every laptop screen, are manufactured by a technology called diamond turning.  In this process, a piece of well-shaped diamond tool is installed on a precision lathe, so that metal parts can be machined with optical-quality surfaces.  These parts are then used as molds to reproduce products such as mentioned above, in a very economical and precise way.  However, in conventional diamond-turning processes, the producible surfaces are limited to several types of rotationally symmetric surfaces, due to the inability of the diamond tool to respond to fast-rotating spindles.  As a result, many well-designed and much-demanded optical surfaces, such as those used in micro-lens arrays, cannot be manufactured with satisfying precision. The proposed research is to design a fast tool servo, which can generate very fast motion at 2000 times of gravity acceleration.  When combined with a precision lathe, the fast tool servo moves the diamond cutting tool in and out over 1000 times in each spindle revolution so that non-rotationally symmetric surfaces can be generated.  We will also design and build a precision spindle that is guided, suspended, and driven by a novel compact electromagnetic actuator.  This actuator can automatically adjust forces on the spindle according to the feedback signals from precision spindle position sensors.  Therefore, the spindle motion errors can be reduced to less than 3 nanometers. The breakthrough results of the proposed work will significantly improve the efficiency and accuracy of manufacturing free-form surfaces for products such as digital projector lenses, digital camera lenses, and so on.