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A method for evaluating the error averaging effect of hydrostatic guides is proposed, which considers three-dimensional profile error of guides. Error averaging models for hydrostatic guides with single pad and double opposed pads are deduced, respectively. Results show that the error averaging effect is influenced by the profile error in both the width and length directions of hydrostatic guides. Additionally, the oil film stiffness plays an essential part in the error averaging effect when a hydrostatic guide is composed of opposed pads. Experimental results show the method is effective for predicting linear motion error caused by components profile error.

Non-rotational symmetric surface machining requires at least three numerically controlled axes, so there exists a desperately need of an ultra-precision vertical linear axis for ultra-precision machine tools. Based on the above consideration, a vertical ultra-precision linear axis has been developed to satisfy the need for non-rotational symmetric surface ultra-precision machining. The paper discusses the design challenges of the vertical ultra-precision linear axis and presents the mechanical structure designed with dual linear motor drive. A guide component and a gravity compensation mechanism have been designed. Finite element models for the vertical ultra-precision were established to evaluate the dynamic performance of the vertical ultra-precision linear axis. Analysis results show that the configuration of the vertical ultra-precision linear axis is reasonable with good dynamic performance.

Non-rotational symmetrical micro-structured surfaces have gained more and more applications in advanced optical systems. To obtain such surfaces with low cost and high efficiency, this paper presents the key technologies for turning of such surfaces including the diamond turning system, tool path generation and tool nose compensation algorithms. The grid based tool path generation algorithm has been proposed for on-line tool path generation. The tool nose compensation is achieved by constructing cubic Hermite interpolation curve which could improve the calculating efficiency greatly. Then several micro-structured surfaces were fabricated and we focused on the analysis of micro lens array (MLA). Height of the spherical cap, diameter of the scope, and the radius of the curvature are evaluated, their maximum deviation from designed values are -2.23%, 2.27%, and 4.29% respectively. This further verified the diamond machining is an enabling method to fabricate high precision non-rotational symmetrical micro-structured surfaces.

A new design is proposed according to the requirement of a 5-axis ultra-precision machine tool for optical manufacture. This investigation was performed to see how the different configure styles influence the static performance characteristics of externally-pressurized air bearings with orifice, such as load capacity and stiffness. Based on the static performance characteristic analysis, the optimum design is done for the externally-bearing system. Finite difference method was used to obtain the numerical solution of Reynolds Equation. Load capacity was the integration of Pressure over the solution area, while the stiffness is the derivative of load capacity to gas film thickness. The load capacity of the externally-pressurized bearing grows with the increase of supply pressure and goes up with the increase of eccentricity of shaft relative to the bearing; the stiffness turns out to be tough with high supply pressure. The stiffness gets a maximum at zero eccentricity of the spindle, and gradually reduces with the increase of the eccentricity. It has proven that there exists an optimum gas-film clearance where maximum value of stiffness is obtained. There is also an optimum gas-film clearance for maximum load capacity. It should be noted that these two values is different. The restrictor throat diameter has an important influence on the stiffness and load capacity, both of which go down while larger diameter is in use. It can be concluded that there exists an optimum gas-film clearance for aerostatic bearing-rotor system. More attentions should be paid on supply pressure, gas-film thickness and orifice diameter to obtain a spindle of good performance.