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薄膜，都是通过一种名为钻石车削的技术制造的。在这个过程中，一件形状良好的钻石刀具被安装在精密车床上，这样金属零件就可以被加工出光学质量的表面。然后这些零件被用作模具，以非常经济和精确的方式再现上述产品。然而，在传统的钻石车削工艺中，可加工表面仅限于几种类型的旋转对称表面，由于金刚石工具无法响应快速旋转的主轴。因此，许多设计良好、要求很高的光学表面，如用于微透镜阵列的光学表面，无法以令人满意的精度制造。建议的研究是设计一种快速工具伺服，它可以在2000倍重力加速度下产生非常快的运动。当与精密车床相结合时，快速工具伺服在每一次主轴旋转中将金刚石刀具进出1000次以上，从而可以生成非旋转对称的表面。我们还将设计和制造一种由新型紧凑型电磁执行器引导、悬挂和驱动的精密主轴。该执行器可以根据精密主轴位置传感器的反馈信号自动调整主轴上的力。因此，主轴运动误差可以减少到3纳米以下。拟议工作的突破性成果将显著提高数码投影仪镜头、数码相机镜头等产品的自由曲面制造效率和精度。

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.