Xuesen Zhao

Fabrication of microstructures on the surface of a micro/hollow target ball by AFM

An AFM-based mechanical scratching technique is employed to fabricate microstructures with a depth of several nanometers on the surface of a micro (the diameter is 0.1–0.5 mm) thin wall and a hollow (the thickness of the wall is 0.8–1.2 µm) glass target ball. Based on analysis of the materials removal mechanism on the hollow target ball surface by an AFM diamond tip, effects of the normal load, fixed conditions on the machining process are studied. Using the AFM-based nanomachining system which is integrated with a high-precision stage, triangular and circular microstructures are fabricated on the target ball surface. Moreover, square taper holes are fabricated by this technique which solves the problems of fabrication of micro inflation holes in inertial confinement fusion (ICF) experiments. It indicates that the AFM-based mechanical machining approach has potential applications in the fields of machining a curved surface and real three-dimensional microstructures.

Study on the auto-leveling adjustment vibration isolation system for the ultra-precision machine tool

The requirement of the vibration isolation system for ultra-precision machine tool was extremely stringent. However, most of the isolation systems currently cannot meet the requirement. Therefore, it is urgently needed to design a new vibration isolation system to fulfill the strict vibration capability required by ultra-precision machine tool. In this paper the structure and principle of the conventional vibration isolation systems composed of air springs were first elucidated thoroughly. Based on these knowledge, we have designed a vibration isolation system with the function of auto-leveling adjustment for a home-made ultra-precision machine tool. The capability of vibration isolation system was validated by an experimental method, in which acceleration-frequency curves were recorded. And post data processing including the analyzing the cut-off frequency and amplitude attenuation were followed. The experimental results demonstrated that the air spring vibration isolation system designed in this paper has the capability to effectively isolate the vibration from the ground: it has a higher attenuation ratio for vibration with a frequency beyond 3 Hz, which preferably meet the vibration isolation requirement of the ultra-precision machine tool.

Nearly arc-length tool path generation and tool radius compensation algorithm research in FTS turning

In the non-rotational symmetrical microstrcture surfaces generation using turning method with Fast Tool Servo(FTS), non-uniform distribution of the interpolation data points will lead to long processing cycle and poor surface quality. To improve this situation, nearly arc-length tool path generation algorithm is proposed, which generates tool tip trajectory points in nearly arc-length instead of the traditional interpolation rule of equal angle and adds tool radius compensation. All the interpolation points are equidistant in radial distribution because of the constant feeding speed in X slider, the high frequency tool radius compensation components are in both X direction and Z direction, which makes X slider difficult to follow the input orders due to its large mass. Newton iterative method is used to calculate the neighboring contour tangent point coordinate value with the interpolation point X position as initial value, in this way, the new Z coordinate value is gotten, and the high frequency motion components in X direction is decomposed into Z direction. Taking a typical microstructure with 4μm PV value for test, which is mixed with two 70μm wave length sine-waves, the max profile error at the angle of fifteen is less than 0.01μm turning by a diamond tool with big radius of 80μm. The sinusoidal grid is machined on a ultra-precision lathe succesfully, the wavelength is 70.2278μm the Ra value is 22.81nm evaluated by data points generated by filtering out the first five harmonics.

Design and Implementation of a Novel Single-Driven Ultrasonic Elliptical Vibration Assisted Cutting Device

In this paper, a novel single-driven ultrasonic elliptical vibration cutting (SDUEVC) device with a succinct structure and a simple assembly is proposed and investigated. A tailored horn with a tilted-slot structure was employed in the designed SDUEVC device. Also, the elliptical trajectory formation mechanism of the designed SDUEVC device was described by using the theory of mechanical vibration. Furthermore, the finite element method (FEM) was used to optimize the tilted-slot structure parameters and there are four parameters selected as the optimization factors. The results indicated that the proposed SDUEVC device can generate larger vertical amplitude than previous SDUEVC devices, which provides an important and positive effect for the cutting performance of the proposed SDUEVC device. According to the optimized results, a prototype SDUEVC device was fabricated and its vibration characteristic was tested. When the excitation signal voltage was 500 Vp-p, the test results indicated that the amplitudes in the axial and vertical directions were 8.7 μm and 6.8 μm, respectively. Furthermore, an elliptical trajectory was generated at the cutting tool tip. Finally, the proposed SDUEVC device was used to fabricate microdimple patterns as the initial application to confirm the feasibility of the proposed SDUEVC device.

An on-machine error compensation method for an ultra-precision turning machine

On-machine error compensation (OMEC) is efficient at improving machining accuracy without increasing extra manufacturing cost, and involves the on-machine measurement (OMM) of machining accuracy and modification of program code based on the measurement results. As an excellent OMM technique, chromatic confocal sensing allows for the rapid development of accurate and reliable error compensation technique. The present study integrated a non-contact chromatic confocal probe into an ultra-precision machine for OMM and OMEC of machined components. First, the configuration and effectiveness of the OMM system were briefly described, and the relevant OMEC method was presented. With the OMM result, error compensation software was then developed to automatically generate a modified program code for error compensation. Finally, a series of cutting experiments were performed to verify the validity of the proposed OMEC method. The experimental results demonstrate that the proposed error compensation method is reliable and considerably improves the form error of machined components.