scholarly journals Theoretical and Experimental Investigation of Surface Topography Generation in Slow Tool Servo Ultra-Precision Machining of Freeform Surfaces

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2566 ◽  
Author(s):  
Duo Li ◽  
Zheng Qiao ◽  
Karl Walton ◽  
Yutao Liu ◽  
Jiadai Xue ◽  
...  
Keyword(s):  
Surface Topography ◽  
Tool Path ◽  
Tool Path Generation ◽  
Surface Generation ◽  
Precision Machining ◽  
Path Generation ◽  
Freeform Surfaces ◽  
Ultra Precision ◽  
Slow Tool Servo ◽  
Radius Compensation

Freeform surfaces are featured with superior optical and physical properties and are widely adopted in advanced optical systems. Slow tool servo (STS) ultra-precision machining is an enabling manufacturing technology for fabrication of non-rotationally symmetric surfaces. This work presents a theoretical and experimental study of surface topography generation in STS machining of freeform surfaces. To achieve the nanometric surface topography, a systematic approach for tool path generation was investigated, including tool path planning, tool geometry selection, and tool radius compensation. The tool radius compensation is performed only in one direction to ensure no high frequency motion is imposed on the non-dynamic axis. The development of the surface generation simulation allows the prediction of the surface topography under various tool and machining variables. Furthermore, it provides an important means for better understanding the surface generation mechanism without the need for costly trial and error tests. Machining and measurement experiments of a sinusoidal grid and microlens array sample validated the proposed tool path generation and demonstrated the effectiveness of the STS machining process to fabricate freeform surfaces with nanometric topography. The measurement results also show a uniform topography distribution over the entire surface and agree well with the simulated results.

Tool path generation for ultra-precision polishing of freeform optical surfaces in an off-axis three-mirror imaging system

2015 ◽  
Vol 231 (5) ◽  
pp. 814-824 ◽  
Author(s):  
Dengpeng Huang ◽  
Lei Zhang ◽  
Shijun Ji ◽  
Ji Zhao
Keyword(s):  
Tool Path ◽  
Imaging System ◽  
Concentric Circle ◽  
Tool Path Generation ◽  
Numerical Control ◽  
Path Generation ◽  
Freeform Surfaces ◽  
Primary Mirror ◽  
Tool Paths ◽  
Ultra Precision

The optical performance of the off-axis three-mirror imaging system can be greatly improved using freeform surfaces. This article focuses on the polishing of the primary mirror and tertiary mirror in an off-axis three-mirror imaging system. The primary mirror and tertiary mirror are fabricated on one monolithic substrate and described by non-uniform rational B-spline–based freeform surfaces. The separated and integrated polishing strategies are presented for polishing the two mirrors on the four-axis computer numerical control polishing platform. A tool path generation approach is proposed for polishing of the non-uniform rational B-spline–based freeform surface. Three kinds of the tool paths are given for ultra-precision polishing of the primary mirror and tertiary mirror with the freeform surfaces. The concentric circle path and the approximately concentric circle path are generated for polishing two mirrors separately, while the spiral path is calculated for integrated polishing of two mirrors simultaneously. The polishing tool posture along the planned tool paths is also analyzed. The ultra-precision polishing experiments of the primary mirror and tertiary mirror on the four-axis computer numerical control polishing platform are performed to verify the proposed approach for tool path generation.

scholarly journals Adaptive Spiral Tool Path Generation for Diamond Turning of Large Aperture Freeform Optics

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 810 ◽  
Author(s):  
Dongfang Wang ◽  
Yongxin Sui ◽  
Huaijiang Yang ◽  
Duo Li
Keyword(s):  
Tool Path ◽  
Tool Path Generation ◽  
Diamond Turning ◽  
Surface Generation ◽  
Machining Efficiency ◽  
Path Generation ◽  
Control Points ◽  
Large Aperture ◽  
Freeform Optics ◽  
Slow Tool Servo

Slow tool servo (STS) diamond turning is a well-developed technique for freeform optics machining. Due to low machining efficiency, fluctuations in side-feeding motion and redundant control points for large aperture optics, this paper reports a novel adaptive tool path generation (ATPG) for STS diamond turning. In ATPG, the sampling intervals both in feeding and cutting direction are independently controlled according to interpolation error and cutting residual tolerance. A smooth curve is approximated to the side-feeding motion for reducing the fluctuations in feeding direction. Comparison of surface generation of typical freeform surfaces with ATPG and commercial software DiffSys is conducted both theoretically and experimentally. The result demonstrates that the ATPG can effectively reduce the volume of control points, decrease the vibration of side-feeding motion and improve machining efficiency while surface quality is well maintained for large aperture freeform optics.

Study on Tool-Path Generation for Ultra-Precision Machining of Optical Lens Array

2012 ◽  
Vol 516 ◽  
pp. 595-599
Author(s):  
Kui Liu ◽  
Pei Ling Liu ◽  
Hu Wu ◽  
Kah Chuan Shaw
Keyword(s):  
Tool Path ◽  
Cutting Tool ◽  
Tool Path Generation ◽  
Numerical Control ◽  
Precision Machining ◽  
Path Generation ◽  
Software Platform ◽  
Optical Lens ◽  
Lens Array ◽  
Ultra Precision

In this study, a computer numerical control (CNC) programming software platform for ultra precision machining of optical surfaces was developed based on an MS Windows application framework and openGL. Using cylindrical coordinates, the tool path can be generated based on the polar angle, radius and a linear coordinate of the Z-axis, as well as cutting tool nose radius compensation. A 3D simulation based on tool path generation was developed for machining verification, which largely reduces the oscillation of the machine during the ultra precision machining process. Ultra precision machining of an optical lens array was carried out on a 5-axis ultra precision machining centre using a single crystalline diamond cutter. The experimental results indicated that the oscillation effect can be largely reduced using the cutting tool path using a super steady machining strategy. This software platform is designed as a framework, where the capability and functions can be expanded by adding in more freeform surface packages.

Study of The Tool Path Generation Method of an Ultra-Precision Spherical Complex Surface Based on a Five-Axis Machine Tool

2021 ◽  
Author(s):  
Tianji Xing ◽  
Xuesen Zhao ◽  
Zhipeng Cui ◽  
Rongkai Tan ◽  
Tao Sun
Keyword(s):  
Surface Roughness ◽  
Tool Path ◽  
Spherical Surface ◽  
Tool Path Generation ◽  
Path Generation ◽  
Tool Paths ◽  
Spherical Surfaces ◽  
Spherical Complex ◽  
Ultra Precision ◽  
Five Axis

Abstract The improvement of ultra-precision machining technology has significantly boosted the demand for the surface quality and surface accuracy of the workpieces to be machined. However, the geometric shapes of workpiece surfaces cannot be adequately manufactured with simple plane, cylindrical, or spherical surfaces because of their different applications in various fields. In this research, a method was proposed to generate tool paths for the machining of complex spherical surfaces based on an ultra-precise five-axis turning and milling machine with a C-Y-Z-X-B structure. Through the proposed tool path generation method, ultra-precise complex spherical surface machining was achieved. First, the complex spherical surface model was modeled and calculated, and then it was combined with the designed model to generate the tool path. Then the tool paths were generated with a numerically controlled (NC) program. Based on an ultra-precision three-coordinate measuring instrument and a white light interferometer, the machining accuracy of a workpiece surface was characterized, and t[1]he effectiveness of the provided tool path generation method was verified. The surface roughness of the machined workpiece was less than 90 nm. Furthermore, the surface roughness within the spherical region appeared to be less than 30 nm. The presented tool path generation method in this research produced ultra-precision spherical complex surfaces. The method could be applied to complex spherical surfaces with other characteristics.

Tool path optimal design for slow tool servo turning of complex optical surface

2016 ◽  
Vol 231 (5) ◽  
pp. 825-837 ◽  
Author(s):  
Xu Chen ◽  
Min Kang ◽  
Xingsheng Wang ◽  
Muhammad Hassan ◽  
Jun Yang
Keyword(s):  
Optimal Design ◽  
Tool Path ◽  
Tool Path Generation ◽  
Interpolation Error ◽  
Machining Accuracy ◽  
Calculation Error ◽  
Path Generation ◽  
Optical Surface ◽  
Toric Surface ◽  
Slow Tool Servo

In order to increase the machining accuracy of slow tool servo turning of complex optical surface, the optimal design for tool path was studied. A comprehensive tool path generation strategy was proposed to optimize the tool path for machining complex surfaces. A new algorithm was designed for tool nose radius compensation which had less calculation error. Hermite segment interpolation was analyzed based on integrated multi-axes controller, and a new interpolation method referred to as triangle rotary method was put forward and was compared with the area method and three-point method. The machining simulation indicated that the triangle rotary method was significant in error reduction. The interpolation error of toric surface was reduced to 0.0015 µm from 0.06 µm and sinusoidal array surface’s interpolation error decreases to 0.37 µm from 1.5 µm. Finally, a toric surface was machined using optimum tool path generation method to evaluate the proposed tool path generation method.

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