Based on chemical-mechanical polishing and combining mechanical and tribochemical polishing techniques, a precision lapping method suitable for parabolic polishing specified by grazing incident X-rays is introduced. Various factors affecting the polishing process are analyzed, and the results show that the proposed method is consistent with Preston's equation and Hertz contact principle. Therefore, this paper proposes a general material removal model based on the above two methods. The mid and high-spatial frequency errors are demanded to reach the requirements with an angular resolution consistently < 6 arcsec HEW and a roughness of 0.3 nm rms (between 1 mm and 0.002 mm spatial frequency range). To achieve the conformal ultra-smooth polishing of focusing mirrors, the process of full-aperture super-smooth pitch polishing is investigated. The influences of key polishing parameters are revealed. The evolution of the surface topology has been studied. A polishing setup is established to carry out experimental polishing to verify the optimum processing parameters obtained by simulations and previous polishing tests. Besides, the effect of abrasive particle size on the roughness is also verified. The roughness of the polished mandrel is measured at different positions, and the optimum roughness reaches Ra 0.359 nm. The polishing approach can significantly reduce the surface roughness of the replication mandrel, satisfying the low energy band focusing requirement of grazing incidence X-ray mirrors.
Over the past few years, atmospheric Inductively Coupled Plasma (ICP) has aroused extensive attention in optical fabrication field since its chemical etching-based processing mode does not mechanically damage work-pieces. However, the principle of chemical etching will inevitably bring some processing temperature while maintaining the efficiency. This makes the ICP jet easily cause thermal damage to the ultra-thin or low thermal conductivity optical elements, even cause the element to crack seriously. Therefore, this paper proposes a velocity-region dual adaptive path planning algorithm, which reduces the processing temperature by limiting the moving velocity of a single path, and achieves the removal of excessive peaks through Repeated traversals.
In this paper, a four-axis ultra-precision lathe for machining large-scale drum mould with microstructured surface is
presented. Firstly, because of the large dimension and weight of drum workpiece, as well as high requirement of
machining accuracy, the design guidelines and component parts of this drum lathe is introduced in detail, including
control system, moving and driving components, position feedback system and so on. Additionally, the weight of drum
workpiece would result in the structural deformation of this lathe, therefore, this paper analyses the effect of structural
deformation on machining accuracy by means of ANSYS. The position change is approximately 16.9nm in the
X-direction(sensitive direction) which could be negligible. Finally, in order to study the impact of bearing parameters on
the load characteristics of aerostatic journal bearing, one of the famous computational fluid dynamics(CFD) software,
FLUENT, is adopted, and a series of simulations are carried out. The result shows that the aerostatic spindle has superior
performance of carrying capacity and stiffness, it is possible for this lathe to bear the weight of drum workpiece up to
1000kg since there are two aerostatic spindles in the headstock and tailstock.
KEYWORDS: Spindles, Finite element methods, Control systems design, Control systems, Modal analysis, Systems modeling, 3D modeling, Nose, Chemical elements, Chemical analysis
An ultra-precision machine tool for machining of the roller has been designed and assembled, and due to the obvious impact which dynamic characteristic of machine tool has on the quality of microstructures on the roller surface, the dynamic characteristic of the existing machine tool is analyzed in this paper, so is the influence of circumstance that a large scale and slender roller is fixed in the machine on dynamic characteristic of the machine tool. At first, finite element model of the machine tool is built and simplified, and based on that, the paper carries on with the finite element mode analysis and gets the natural frequency and shaking type of four steps of the machine tool. According to the above model analysis results, the weak stiffness systems of machine tool can be further improved and the reasonable bandwidth of control system of the machine tool can be designed. In the end, considering the shock which is caused by Z axis as a result of fast positioning frequently to feeding system and cutting tool, transient analysis is conducted by means of ANSYS analysis in this paper. Based on the results of transient analysis, the vibration regularity of key components of machine tool and its impact on cutting process are explored respectively.
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