Hunan Key Laboratory Of Ultra Precision Machining Technology

Changsha, China

Hunan Key Laboratory Of Ultra Precision Machining Technology

Changsha, China

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Peng W.,National University of Defense Technology | Peng W.,Hunan Key Laboratory of Ultra precision Machining Technology | Guan C.,National University of Defense Technology | Guan C.,Hunan Key Laboratory of Ultra precision Machining Technology | And 2 more authors.
Optics Express | Year: 2014

Material removal rate has greatly relied on the distribution of shear stress and dynamic pressure on the workpiece surface in hydrodynamic effect polishing (HEP). Fluid dynamic simulation results demonstrate that the higher rotation speed and smaller clearance will cause the larger material removal rate. Molecular dynamic (MD) calculations show the bonding energy of Si-O in the silicon-oxide nanoparticle is stronger than that in the quartz glass, and therefore the atoms can be dragged away from the quartz glass surface by the adsorbed silicon-oxide nanoparticle. The deep subsurface damage cannot be efficiently removed by HEP due to its extremely low removal rate. However, the subsurface damaged layer can be quickly removed by ion beam figuring (IBF), and a thinner layer containing the passivated scratches and pits will be left on the surface. The passivated layer is so thin that can be easily removed by HEP process with a low material rate under the large wheel-workpiece clearance. Combined with the IBF process, the subsurface damage and surface scratches have been efficiently removed after the HEP process. Meanwhile there are not obvious duplicated marks on the processed surface and the surface roughness has been improved to 0.130nm rms, 0.103nm Ra. © 2014 Optical Society of America.


Peng Y.,National University of Defense Technology | Peng Y.,Hunan Key Laboratory of Ultra precision Machining Technology | Dai Y.,National University of Defense Technology | Dai Y.,Hunan Key Laboratory of Ultra precision Machining Technology | And 5 more authors.
International Journal of Machine Tools and Manufacture | Year: 2016

Because of finite stiffness of grinding system, grinding force will cause the tool deflection (the difference between actual cutting depth and nominal cutting depth). During helix path contour grinding, the grinding condition are variable at different grinding point which will bring forward different tool deflection and result in dimensional errors. This paper presents an error analysis model during multi-pass grinding, which can predict the accumulation process of surface profile error induced by tool deflection. It establishes the relationship between profile error and grinding parameters. The estimation method of key model parameters is described in the proposed model through series of experiments. According to the error analysis model, we can implement the varied feed rate and varied cutting depth method for compensating the profile error. The grinding experimentation and compensation grinding verifies the validity of error analysis model and effectiveness of compensation method, and the profile error reduced by 82.1% comparing with grinding process without compensation. © 2016 Elsevier Ltd


Peng W.,National University of Defense Technology | Peng W.,Hunan Key Laboratory of Ultra precision Machining Technology | Guan C.,National University of Defense Technology | Guan C.,Hunan Key Laboratory of Ultra precision Machining Technology | And 2 more authors.
Optical Engineering | Year: 2014

A material removal mechanism of ceria particles with different sizes in a glass polishing process was investigated in detail. Contrast polishing experiments were carried out using ceria slurries with two kinds of particle sizes and different amounts of hydrogen peroxide (H2O2) added in the slurries. The Ce3+ ions on the surface of the ceria particles were gradually oxidized to Ce4+ with increased H 2O2 concentration. It was found that the material removal rate (MRR) decreased sharply with an increasing concentration of H 2O2. There was no material removal when the concentration reached 2.0% for nanoparticle slurry. Nevertheless, the application of microparticles made the MRR decrease to a constant value when excessive H 2O2 was added. By comparison, we conclude that the material is removed by chemical reaction for ceria nanoparticles, while chemical reaction and mechanical abrasion simultaneously take place for ceria particles with sizes at scale of micrometers in the glass polishing process. It is clearly demonstrated from the experimental results that Ce3+ instead of Ce4+ ions play an important role in chemically reacting with the glass surface. An ultrasmooth surface with root-square-mean roughness of 0.272 nm was obtained after being polished by ceria nanoparticles. © 2014 Society of Photo-Optical Instrumentation Engineers.


Zhou L.,National University of Defense Technology | Zhou L.,HuNan Key Laboratory of Ultra precision Machining Technology | Dai Y.,National University of Defense Technology | Dai Y.,HuNan Key Laboratory of Ultra precision Machining Technology | And 6 more authors.
Optics Express | Year: 2015

A translation-reduced ion beam figuring (TRIBF) technique for five-axis ion beam figuring (IBF) plants is proposed to process large size components which cannot be processed in the traditional way. This novel technique enhances the capability of five-axis IBF plants by taking advantage of their rotation axes. The IBF kinematic model is described and the TRIBF processing technique is established by solving the motion parameters. Verification experiments are conducted on a 150 mm diameter planar mirror. This mirror was processed by TRIBF technique with only a 100 mm translation stage. The surface error was reduced from initial 10.7nm rms to 1.3nm rms within 97 minute processing time. The result indicates that the TRIBF processing technique is feasible and effective. © 2015 OSA.


Lu Y.,National University of Defense Technology | Lu Y.,Hunan Key Laboratory of Ultra precision Machining Technology | Xie X.,National University of Defense Technology | Xie X.,Hunan Key Laboratory of Ultra precision Machining Technology | And 2 more authors.
Applied Optics | Year: 2016

First, we introduce requirements for the ion beam polishing tool used in the subnanometer precision process. Based on the ion beam figuring (IBF) principle, the definitive factor of the IBF capability is analyzed, and the deficiencies of the ion beam polishing tool are identified. The effect of focused ion optics on the ion beam removal function is based on theoretic calculation and computer simulation; and focused three-grid ion optics are developed and tested. Finally, a 150 mm flat optics element is figured and results show that the contour error decreases from 15.58 nm RMS to 0.796 nm RMS, demonstrating that the ion beam polishing tool is very efficient for optical IBF. © 2016 Optical Society of America.


Tian F.,National University of Defense Technology | Tian F.,Hunan Key Laboratory Of Ultra Precision Machining Technology | Yin Z.,National University of Defense Technology | Yin Z.,Hunan Key Laboratory Of Ultra Precision Machining Technology | And 2 more authors.
International Journal of Advanced Manufacturing Technology | Year: 2016

The fabrication of high-quality freeform surfaces is based on ultra-precision diamond turning with fast tool servo (FTS) technology which allows direct machining of the freeform surfaces with sub-micrometric form accuracy and nanometric surface roughness. Surface roughness is an important factor in evaluating the performance of the optical freeform surfaces. This paper presents a theoretical and experimental analysis of surface generation in ultra-precision single-point diamond turning. In this model, we take into consideration the basic machining parameters as well as the relative vibration between the workpiece and the tool in both the cutting and feeding directions. Theoretical model is built to predicting the surface roughness of machined flat surface as well as freeform surfaces. A series of experiments have conducted and the results show good correlation between the theoretical model and the fabricated surfaces. © 2016 Springer-Verlag London


Tian F.,National University of Defense Technology | Tian F.,Hunan Key Laboratory Of Ultra Precision Machining Technology | Yin Z.,National University of Defense Technology | Yin Z.,Hunan Key Laboratory Of Ultra Precision Machining Technology | And 2 more authors.
International Journal of Advanced Manufacturing Technology | Year: 2016

Single point diamond turning (SPDT) based on tool servo system is one of the significant techniques to fabricating the optical freeform surfaces. The conventional fast tool servo (FTS) actuated by piezoelectric actuator has the problem of short stroke, while the drawback of the slow tool servo (STS) is low frequency response. This paper briefly presents a novel long range fast tool servo (LRFTS) with high frequency response and long stroke. The total stroke can reach up to 30 mm. The LRFTS uses a voice coil motor as the actuating element and air bearings as the guide mechanism. The LRFTS utilizes a linear encoder to measure the displacement of the tool for closed loop control. The servo performance of the LRFTS system’s amplitude and frequency response is analyzed. The physical model of the LRFTS is identified. A series of experiments have been conducted to verify the performance of the designed LRFTS. Micro-lens array fabrication experiments on an aluminum part are conducted using the designed LRFTS. The factors influencing the surface roughness have been analyzed. © 2016 Springer-Verlag London


Liao W.,National University of Defense Technology | Liao W.,Hunan Key Laboratory of Ultra Precision Machining Technology | Dai Y.,National University of Defense Technology | Dai Y.,Hunan Key Laboratory of Ultra Precision Machining Technology | And 2 more authors.
Applied Optics | Year: 2014

Morphology evolution at microscopic scales has an inseparable relationship with surface material behaviors, especially during ultrasmooth surface fabrication. In this work, the influence of initially existing local densification on ion nanopatterning of a fused-silica surface is investigated. Our research results indicate that fused-silica surfaces will easily densify permanently under a compressive load, exhibiting an anisotropic surface at the nanoscale. During the subsequent ion-beam sputtering process, the densification-dependent sputtering would influence and even dominate surface morphology evolution, which is identified as being an important evolution mechanism. However, ion-induced relaxation mechanisms will overcome surface roughening in the absence of local densification, and an ultrasmooth surface with root mean square roughness down to 0.06 nm is obtained in our experiment. © 2014 Optical Society of America.


Liao W.,National University of Defense Technology | Liao W.,Hunan Key Laboratory of Ultra Precision Machining Technology | Dai Y.,National University of Defense Technology | Dai Y.,Hunan Key Laboratory of Ultra Precision Machining Technology | And 4 more authors.
Applied Optics | Year: 2014

Ion beam figuring (IBF) is established for the final precision figuring of high-performance optical components, where the figuring accuracy is guaranteed by the stability of the removal function and the solution accuracy of the dwell time. In this deterministic method, the figuring process can be represented by a two-dimensional (2D) convolution operation of a constant removal function and the dwell time. However, we have found that the current 2D convolution operation cannot factually describe the IBF process of curved surfaces, which neglects the influences of the projection distortion and the work-piece geometry on the removal function. Consequently, the current 2D convolution algorithm would influence the solution accuracy for the dwell time and reduce the convergence of the figuring process. In this part, based on the material removal characteristics of IBF, a mathematical model of the removal function is developed theoretically and verified experimentally. Research results show that the removal function during IBFof a curved surface is actually a dynamic function in the 2D convolution algorithm. The mathematical modeling of the dynamic removal function provides theoretical foundations for our proposed new algorithm in the next part, and final verification experiments indicate that this algorithm can effectively improve the accuracy of the dwell time solution for the IBFof curved surfaces. © 2014 Optical Society of America.


Liao W.,National University of Defense Technology | Liao W.,Hunan Key Laboratory of Ultra Precision Machining Technology | Dai Y.,National University of Defense Technology | Dai Y.,Hunan Key Laboratory of Ultra Precision Machining Technology | And 4 more authors.
Applied Optics | Year: 2014

Ion beam figuring (IBF) is established for the final precision figuring of optical components. In this deterministic method, the figuring process is represented by a two-dimensional (2D) convolution operation of a constant removal function and the dwell time, where the figuring precision is guaranteed by the stability of the removal function as well as the solution accuracy of the dwell time. However, the current 2D convolution equation cannot factually reflect the IBF process of curved surfaces, which neglects the influence of the projection distortion and the workpiece geometry. Consequently, the current convolution algorithm for the IBF process would influence the solution accuracy for the dwell time and reduce the convergence of the figuring process. In this part, we propose an improved algorithm based on the mathematical modeling of the dynamic removal function in Part A, which provides a more accurate dwell time for IBF of a curved surface. Additionally, simulation analysis and figuring experiments are carried out to verify the feasibility of our proposed algorithm. The final experimental results indicate that the figuring precision and efficiency can be simultaneously improved by this method. © 2014 Optical Society of America.

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