Papers by Keyword: Surface Accuracy

Abstract: The research analyzed the distribution of cutter position point data outputted by software CAM, based on the precision of surface milling. The model of the tool-path is established by using the piece-wise interpolation function, combining with the distribution characteristic of cutter position point. The segmentation optimization of the tool-path is also realized via the limitation and judgment of the string high error of the segmented trajectory and the optimization algorithm is integrated into the post-processing to improve the precision of the surface milling. The experiment results of surface milling show a positive effect of cutter position point optimization on surface milling accuracy.

Abstract: The paper proposes a new ultra-high-precision machining technique, based on magnetic abrasive finishing, to achieve both high dimensional accuracy and surface accuracy of microscale-diameter materials that are difficult or impossible to machine conventionally. Microscale-diameter zirconia ceramic bars were used as the workpieces, and were machined by means of the proposed technique at different workpiece revolution speeds (1,000, 10,000, 20,000, and 35,000 rpm). Machining depth increased with workpiece revolution speed, and was the greatest for the highest speed studied of 35,000 rpm. The technique also yielded excellent performance in terms of the surface roughness; the initial surface roughness (Ra) of 0.18 µm was decreased to 0.02 µm under machining at 35,000 rpm for 40 s. SEM and AFM micrographs gave evidence of the technique’s high performance.

Abstract: To research the surface accuracy sensitivity of mesh antennas to cable length, the whole coordinates interaction method (WCIM) and the difference algorithm for sensitivity calculation are used. The calculating model of a large hoop truss mesh antenna was studied, and then some valuable conclusions were drawn from analyzing the calculating results of the numerical example, the feasibility of the approach were also proved. In the same situation of equilibrium, the surface accuracy sensitivity to the length of the individual cable is different. With the initial tensions in the networks increase, the sensitivity to the length of all the cables and the range of sensitivity decrease. The algorithm presented can be used to optimize the networks and adjust the surface accuracy of mesh antennas.

Abstract: Aspheric detection technology has always been the key factor which affects the further enhance of aspheric precision manufacturing. Without high-precision detection methods and instruments to fit processing accuracy, aspherical precision machining and ultra-precision machining is difficult to achieve. A contact measurement of aspheric surface detection technology and its error analysis are mainly introduced in this paper, and testing equipment is the UK Taylor Hubson profilometer with instrument precision 0.2μm and measure the caliber 200mm.

Abstract: In mechanical processing, according to the requirements of components’ high surface quality, this paper makes a structure design of high-speed cylindrical grinding machine transmission system. Such structure is mainly used in high-speed grinding and powerful grinding, so as to improve the grinding efficiency. The design provides a certain basis for the further research of grinding machine structure.

Abstract: This paper introduces the affecting factors of tool clamping error of the axis direction in aspheric manufacturing process, and analyses the effects of tool clamping errors of the wheel along X and Y directions on processing area and contour error curve in depth in the aspheric manufacture parallel grinding, and calculates the relationship between tool clamping error of axis direction and aspheric shape error, and applies the theory in the machining process. The experiments show that the processing time decreases by 60% with satisfactory precision. The surface accuracy of 0.15 μm (0.237λ) of PV value and 0.023 μm (0.036λ) of RMS value can be achieved for 51.5 mm diameter aspheric surfaces. The theoretical analyses and error compensation methods are validated through the experiments, and the results show that the rapid process of aspheric surfaces can be realized.

Abstract: This paper describes the basic data process of antenna surface geometrical measurement and the quality evaluation indexes, which are surface accuracy and its uncertainty.The peak to peak value of normal deviation is used to characterize the surface accuracy,and its deviation is defined as its uncertainty.The measurement errors are given under repeated measuring conditions.Under repeated measuring conditions,the simulation method is that adding the measurement errors calculated by repeated measurement to theoretical coordinates.Under single measuring conditions, the first step is to convert the measurement data from the measuring coordinate system to the design coordinate system to get the transformation parameters;then use these parameters to convert theoretical coordinates to the measurement coordinate system;and then add measurement errors to transformed coordinates for simulation.The key point is adding measurement errors to the data which do not contain measurement errors.The simulation and actual measurement experiments of a Φ0.7 meter antenna were conducted,which showed that the method is correct.

Abstract: In this paper stable eccentric immersed polishing is investigated according to Preston equation. The polishing trace, speed, density of polishing fluid etc were analyzed in detail. The polishing practicability of the technology was verified for polishing a piece of zerodur and the supersmooth surface with the flatness of PV0.04μm was obtained. The roughness of the surface has decreased to Ra0.37nm from initial Ra1.5nm after polishing 120 minutes.

Abstract: As a new fixed-abrasive machining method, chemo-mechanical grinding (CMG) is developed from chemical mechanical polishing (CMP), with the obvious advantage of geometric accuracy determinacy and no slurry. To improve material removal rate and enhance the popularity of CMG, this paper introduces a combined grinding method, i.e., two dimensional ultrasonic vibration assisted CMG (2D-UACMG). Si wafer is taken as the workpiece and the influence of ultrasonic vibration modes and process parameters on the surface roughness and the material removal is examined. The results show 2D-UACMG can obtain better surface quality with little surface damage at nanometer level compared with the conventional CMG without the ultrasonic vibration.