scholarly journals Generation and characterization of ultra-precision compound freeform surfaces

2019 ◽  
Vol 103 (1) ◽  
pp. 003685041988011
Author(s):  
Lingbao Kong ◽  
Yingao Ma ◽  
Mingjun Ren ◽  
Min Xu ◽  
Chifai Cheung
Keyword(s):  
Tool Path ◽  
Complex Geometry ◽  
Experimental Studies ◽  
Machining Process ◽  
Freeform Surface ◽  
Freeform Surfaces ◽  
Machining Errors ◽  
Hybrid Machining Process ◽  
Ultra Precision

Compound freeform surfaces are widely used in bionic and optical applications. The manufacturing and measurement of such surfaces are challenging due to the complex geometry with multi-scale features in a high precision level with sub-micrometer form accuracy and nanometer surface finish. This article presents a study of ultra-precision machining and characterization of compound freeform surfaces. A hybrid machining process by combining slow slide servo and fast tool servo is proposed to machine compound freeform surfaces. The machining process for this hybrid tool servo is explained, and tool path generation is presented. Then, a normal template-based matching and characterization method is proposed to evaluate such compound freeform surfaces. Experimental studies are undertaken to machine a compound freeform surface using the proposed method based on a four-axis ultra-precision machine tool. The machined compound freeform surface is also measured and characterized by the proposed analysis and characterization method. The experimental results are presented, and the machining errors for compound freeform surfaces are also discussed.

A Framework of an Integrated Platform for Modelling and Measurement of Freeform Surface Generation in Ultra-Precision Raster Milling

2007 ◽  
Vol 339 ◽  
pp. 422-426 ◽  
Author(s):  
Ling Bao Kong ◽  
Chi Fai Cheung ◽  
Wing Bun Lee ◽  
Sandy To
Keyword(s):  
Measurement System ◽  
Tool Path ◽  
Surface Generation ◽  
Freeform Surface ◽  
Product Model ◽  
Freeform Surfaces ◽  
Design Component ◽  
Integrated Platform ◽  
Ultra Precision ◽  
Efficient Measurement

This paper presents an integrated platform for modelling and measurement of freeform surface generation in ultra-precision raster milling. It is composed of several components which are optics design component, tool path generator, modelling system, measurement system, evaluation component, compensation component and optimization component, respectively. The research emphasizes on modelling and simulation of freeform surface generation, the prediction of the cutting performance and hence the optimization of cutting strategy in the ultra-precision raster milling of freeform surfaces. A measurement system is also proposed to carry out a fast and efficient measurement plan of freeform surfaces. Non-uniform Rational B-Spline (NURBS) will be employed for the development of the integrated platform which will meet Standard for the Exchange of Product model data (STEP).

Dividing the Complicated General Shapes of the Surface into Partial Elements According to Curvature (Gauss and Maximal Curvature) and its Multi-Axis Machining

2014 ◽  
Vol 693 ◽  
pp. 225-230
Author(s):  
Jiří Šafka ◽  
Martin Lachman ◽  
Petr Zelený ◽  
Martin Seidl
Keyword(s):  
Standard Method ◽  
Gaussian Curvature ◽  
Tool Path ◽  
Working Time ◽  
Machining Process ◽  
Freeform Surface ◽  
Freeform Surfaces ◽  
Surface Areas ◽  
Complex Shapes ◽  
Optimal Setting

The paper deals with multi-axis machining of complex shapes of freeform surfaces. Machining of such surfaces is very difficult and the critical operation is the optimal setting of tilt and lead angle which, along with other parameters, must ensure collision-free machining. This paper describes the possible dividing of solved freeform surface areas into partial elements with similar properties from CAD data using Matlab software instruments. The partition is solved by algorithms calculated according to the curvature of the surface using both methods the maximum and the Gaussian curvature. These partial elements can be machined separately which allows employment of tools with optimal dimensions for individual elements. This process enables significant reduction of tool-path necessary for machining these shapes which also leads to reduction of the working time. Furthermore, there are practical examples including a comparison of standard method and the use of machining process optimized by the algorithm in this article.

Recognition of Freeform Surface Machining Features

2010 ◽  
Vol 10 (4) ◽  
Author(s):  
Jun Wang ◽  
Zhigang Wang ◽  
Weidong Zhu ◽  
Yingfeng Ji
Keyword(s):  
Critical Points ◽  
Computer Aided Design ◽  
Tool Path ◽  
Machining Process ◽  
Freeform Surface ◽  
Critical Surface ◽  
Machining Features ◽  
Computer Aided ◽  
Freeform Surface Machining ◽  
Machining Process Planning

This paper describes a method of machining feature recognition from a freeform surface based on the relationship between unique machining patches and critical points on a component’s surface. The method uses Morse theory to extract critical surface points by defining a scalar function on the freeform surface. Features are defined by region growing between the critical points using a tool path generation algorithm. Several examples demonstrate the efficiency of this approach. The recognized machining features can be directly utilized in a variety of downstream computer aided design/computer aided manufacturing (CAM) applications, such as the automated machining process planning.

Inspection Technology for F-Theta Lens: Practices and Discussions

2007 ◽  
Vol 364-366 ◽  
pp. 1191-1196 ◽  
Author(s):  
Hua Li ◽  
Suet To ◽  
Ling Bao Kong ◽  
Chi Fai Cheung ◽  
Wing Bun Lee
Keyword(s):  
Measurement Methods ◽  
Freeform Surface ◽  
Measurement Technology ◽  
Measuring Instruments ◽  
Freeform Surfaces ◽  
Existing Problems ◽  
Laser Scanners ◽  
Pros And Cons ◽  
Lens Surface

This paper presents the inspection technology for a freeform surface component which is named F-theta lens. F-theta lens is widely used in laser scanners, printers, etc. Freeform characterization is one of the main approaches to verify the manufacturing precision of freeform surface. At present, there is still a lack of techniques for the characterization of freeform surfaces. This study aimed to explore some approaches to inspect freeform surfaces. Two types of measurement methods, namely contact and non-contact measurement methods, are employed to measure the F-theta lens surface. The pros and cons, the existing problems, different applications and areas for improvement of the two methods are discussed. A series of advanced measuring instruments are used in the measurement process. A brief description of measurement mechanisms of these instruments is also presented. As a whole, this paper contributes to the development of the precision measurement technology for optical freeform surfaces.

Development of Cutting Strategy in Ultra-Precision Raster Milling of Freeform Surface

2014 ◽  
Vol 633-634 ◽  
pp. 615-619
Author(s):  
Su Juan Wang ◽  
Su Et To ◽  
Xin Chen ◽  
Jian Qun Liu
Keyword(s):  
Cutting Parameters ◽  
Integrated System ◽  
Machining Process ◽  
Freeform Surface ◽  
Machining Time ◽  
Tool Paths ◽  
Nc Program ◽  
Ultra Precision ◽  
Cutting Strategy

This paper studies the development of cutting strategy in the fabrication of freeform surface in ultra-precision raster milling (UPRM). The tasks of developing cutting strategy in freeform machining involve in the selection of cutting parameters and the planning of tool paths. An integrated system is built in this study to develop the cutting strategy, automatically generate NC program, simulate the tool paths and machining process, as well as make predictions for the machining time and the surface quality of the raster milled freeform surface. Experiment is conducted to verify the developed system and the experimental results show that the system is applicable for the machining of freeform surface in UPRM. This study therefore contributes to avoiding the need to conduct expensive and time consuming trial cutting tests to ensure the product quality in the freeform machining.

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.

Measurement Scheme Synthesis in Multi-Station Machining Systems

2004 ◽  
Vol 126 (1) ◽  
pp. 178-188 ◽  
Author(s):  
Dragan Djurdjanovic ◽  
Jun Ni
Keyword(s):  
Genetic Algorithm ◽  
Machining Process ◽  
Human Knowledge ◽  
Quantitative Characterization ◽  
Root Cause ◽  
Measurement Scheme ◽  
Machining Errors ◽  
Synthesis Procedure ◽  
Selection Of

Different sets of measurements carry different amounts of information about the root causes of quality problems in machining. The selection of measurements in multi-station machining systems is currently a slow and error-prone process based on expert human knowledge. In this paper, we propose systematic procedures for synthesizing measurement schemes that carry the most information about the root causes of dimensional machining errors. The amount of root cause information conveyed by a given set of measurements was assessed using the recently introduced formal methods for quantitative characterization of measurement schemes in multi-station machining systems. The newly proposed measurement scheme synthesis procedures were applied to devising measurement schemes in an automotive cylinder head machining process. It was observed that the measurement scheme synthesis procedure based on a genetic algorithm robustly outperformed the synthesis procedures based on the heuristics of successive measurement removal.

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