基于旋转变换的鞋楦变翘曲面重构CAD技术

为推动鞋楦设计的快速化、个性化、多样化发展,提出并实现了一种基于旋转变换的鞋楦变翘曲面重构CAD技术。交互选定两变换截面,通过旋转变换将鞋楦前翘高、后翘高等参数值变换到个性化设计需求值;对变换后的鞋楦进行均化处理,实现两变换截面处的鞋楦曲面平滑过渡;对楦底腰窝部中轴线进行微调并将微调量映射到鞋楦模型上来设计与变换后鞋楦相匹配的鞋楦腰窝段。利用提出的曲面重构过程在MATLAB软件平台上设计了参数化和可视化交互式两种方法进行鞋楦变翘设计的CAD模块,其界面具有操作简单方便、易于实时编辑的特点。通过对算法实现结果的高斯曲率和体积进行分析,rhf 验证了重构后鞋楦模型能很好地保持原鞋楦的合脚性及曲面光顺性特征。     

基于CAD/CAM软件的鞋楦逆向设计与制造

本文运用CAD/CAM软件—Geomagic Studio、CimatronE,以鞋楦逆向设计为实例,论述了点云处理、错误修复、曲面生成的方法,对样品鞋进行逆向设计及数控加工程序编制,提出了一套完整的鞋楦逆向设计及数控加工的方法,并为模具设计提供了建构复杂曲面模型的有效途径。     

以Pro/E和MasterCAM为基的鞋楦反求与仿真加工

运用Pro/E逆向技术,对鞋楦原始点云进行处理,并运用小平面建模和重新造型的方法重构鞋楦曲面,完成鞋楦实体模型的构建,然后将实体模型导入MasterCAM软件仿真加工。由于鞋楦为不规则的回转体,故采用四轴加工方法,完成鞋楦的仿真。所做的反求为鞋楦数据的保存和网络化制造提供了支持,同时仿真加工验证了鞋楦模型实际加工的可行性。     

鞋楦CAD系统中的离散设计方法

提出鞋楦的离散设计方法，该方法通过3坐标测量机获得鞋楦表面数据，经过数据预处理、参数化和截面曲线构建等操作，得到鞋楦CAD系统中的鞋楦离散模型，为数控编程、帮样设计等后续应用所用。     

特征尺寸驱动的鞋楦参数化设计

针对鞋楦数字化设计中对非线性尺寸的约束要求,提出一种基于微分坐标变形的尺寸驱动曲面变形方法,实现围长驱动的楦型设计。基于足-楦尺寸的对应关系修改鞋楦上的非线性尺寸,将围长尺寸变化映射为围线形状的变化,再由变化后的围线形状通过网格变形技术转化为楦型曲面的形状修改。通过迭代计算,可以保证围度曲线长度的精确约束;同时,根据楦型设计规律增加的位置约束和方向约束使变形后的曲面能够继承原有楦型曲面内在的形状特征;拉普拉斯变形拥有的特征保持性特点使变形后的鞋楦仍然保持原有的楦型样式,且其最小二乘意义下的求解框架有利于均布计算误差,使变形更加光顺、自然。试验结果表明,所提方法变形自然,实用性强。     

Shoe Last Machining Using Virtual Digitising

Shoe lasts are the moulds used in the footwear industry in order to mount the shoe. Most of the machines used in the sector to make lasts are simply mechanical copiers. CAD/CAM systems have just arrived in the shoe last market but their accuracy and efficiency is no better than traditional machines, and so it is difficult to persuade the industry to adopt new systems. A tool-path generation algorithm that takes advantage of traditional copier systems that do not fulfil the CNC standards is presented in this paper. The tool path is computed from a "virtually digitised" model of the last surface. The algorithm is then analysed in terms of computing cost and accuracy, and refined by applying a series of optimisations. Some computer architectures are proposed in order to reduce the computation time. The proposed algorithm has been successfully implemented in a commercial CAD/CAM system specialised for shoe-last making. Finally, some illustrative examples are given.     

Technical evaluation of a CAD system for orthopaedic shoe-upper design.

Computer aided design is now employed routinely in the volume shoe trade. New styles are developed on a three-dimensional image of the last followed by automated pattern generation and engineering. It is suggested that such systems could be useful in the orthopaedic footwear industry although the different requirements for these bespoke products need careful consideration. A clinical trial has been conducted on the Shoemaster (Clarks Shoes) upper design system both to assess its technical capabilities and to consider its role in improvement of service and cosmetic appearance. This particular system works throughout on a three-dimensional representation of the shoe last, which offers particular advantages for integration with shape capture and reproduction. The report concentrates on the technical evaluation to assess (a) its ability to work with unusual last shapes dictated by medical requirements and (b) its potential for integration into a complete computer system for design of both shoe lasts and shoe uppers. The trial indicates that this particular system is promising in both respects.     

鞋楦夹具设计方法研究

针对鞋楦外形轮廓不能由初等解析曲面构成,需要有效快速提取鞋楦曲面数据信息,提出了一种基于CATIA二次开发的鞋楦表面信息提取方法。对鞋楦表面形状及工艺要求进行了分析,并根据形封闭原理和定位夹紧原则提出鞋楦零件的定位夹紧方案,最后,运用雅可比矩阵进行夹紧计算。研究结果验证了所提的定位夹紧方案的可行性。     

Rapid parametric design methods for shoe-last customization

With the development of computer-aided design (CAD) technology and increasing demands of customized footwear, shoe-lasts are requested to be designed rapidly so as to speed-up the process of footwear manufacturing. Thus, this study presents a CAD system for shoe-last rapid customized design based on the piecewise reconstruction to realize the interactive deformation and separate/global shoe-last form reuse. First, piecewise remodeling method is proposed based on the multi-layer parametric definition and contour curves are extracted from the mesh. Then, five types of proper constraints to support surface manipulation are proposed, and the draft-driven deformation by the contour curve bending can realize the interactive local surface design in free angle of view. Finally, shoe-last styles can be saved and reused globally or separately to share design results between different shoe-lasts. Experimental examples show that customized shoe-lasts can be easily and rapidly generated by adopting the parametric design methods.     

基于椭圆拓扑变换的叶片二维叶型参数化方法

叶型参数化方法服务于叶片设计、制造和再制造全生命周期。针对目前叶型参数化方法难以兼顾造型参数几何含义直观和叶型曲率及曲率导数的连续性问题,提出了一种基于椭圆拓扑变换的二维叶型参数化方法。该方法基于椭圆与叶型曲率分布特征与拓扑结构的一致性,通过构造多个拓扑变换使椭圆变形成二维叶型。在变形过程中,建立了叶型主要几何特征参数与造型参数的一一对应关系且自然地保持了椭圆的高阶连续性。为验证该方法的有效性,对不同几何特征的叶型进行了反演验证。结果表明,与现有方法相比,该方法可用更少的造型参数实现更高的拟合精度;反演叶型曲率及曲率的导数均连续变化;反演叶型和原始叶型气动性能保持很好的一致性;改变单个造型参数可直观地改变叶型几何特征。因此,该参数化方法更易设计出低损失高负荷的叶型,传递的设计意图也更易被制造和再制造环节理解使用,有利于保障叶片的最终服役性能。     

鞋楦曲面重构

本文根据鞋楦曲面体的形状特征,探讨了鞋楦曲面片的划分问题,并以双三次NUBRS曲面方法为工具,利用其良好的 特性,通过调整权因子和控制顶点,可灵活地改变曲面的形状,实现鞋楦曲面重构。     

STEP-NC compliant process planning of additive manufacturing: remanufacturing

Additive manufacturing is becoming one of the key methods for reproducing repair sections in remanufacturing processes. The major advantage of using additive processes is to minimize production time and waste. However, the surface quality and shape accuracy are usually insufficient for the final product because the approximated representation format causes the accumulation of the error during the geometric operations of the process planning. This limitation is a barrier to utilize additive processes as finishing processes, such as general metal cutting. There is need to improve the final quality of parts obtained with additive manufacturing. In this paper, STEP-based numerical control (STEP-NC)-based process planning is applied to the additive manufacturing. ISO 14649 (STEP-NC) describes part programs with geometric data directly and also contains the information necessary for the intelligent process planning. This paper proposes the STEP-NC-based representation method of additive manufacturing and the series of geometric reasoning to automate the derivation of the repair section. The proposed representation has the benefits to provide a high accuracy for the final surface and to describe multiple materials. Topological data maintain low error during the series of process planning through the CAD-CAM-CNC chain. The proposed platform supports consideration of the process tolerance and comparison of the selected plan with alternative processes. In order to show the practical advantages, an analysis of the remanufacturing process is carried out. The case study of remanufacturing a pocket part is presented in order to validate the proposed process plan. The result of the case study shows the improvement in terms of automatic process planning and surface quality accuracy.     

基于Imageware和UG的鞋楦逆向构建与数控仿真加工

运用Handyscan 3D激光扫描仪测得鞋楦点云数据,利用Imageware软件完成鞋楦实体模型的构建,然后将实体模型导入UG软件进行仿真加工。仿真加工结果验证了鞋楦模型实际加工的可行性。     

鞋楦曲面反求

介绍了鞋楦数据类型,母楦曲面数据检测的方法和特点,并讨论了测量头环形面与母楦的切触点不同的问题,在此基础上,提出一种数据处理方法,为测量头环形面建立了空间坐标系,并推导出相应的空间方程,最终把母楦表面离散数据点的计算,转换为射线簇和测量头环形面求交问题,利用数值分析中的二分法逐步逼近求解,从而获得母楦表面离散数据点的位置值.     

鞋楦曲面的逆向设计与数控加工

探讨了基于逆向工程的鞋模曲面设计方法,利用Laser-RE600型激光扫描系统采集了鞋模曲面的几何数据,将数据导入逆向软件Geomagic Studio中进行数据拼接、去噪和重新采样等处理,并将处理后的点云数据导入Pro/E软件中完成了鞋楦曲面的三维重构,最后利用Mastercam X4软件对鞋楦母模进行了NC仿真加工,为复杂零件的数字化逆向设计提供参考。     

Computer-aided process planning for NC tool path generation of complex shoe molds

This paper presents a computer aided process planning (CAPP) system for numerical control tool path generation of complex shoe molds. This CAPP system includes both the automation of auxiliary boundary curve generation and machining strategies. The automation of auxiliary boundary curve generation and machining strategies make tool path generation more accurately and efficiently. Traditional shoe mold making is a very tedious process. Even with the utilization of computer-aided design and computer-aided manufacturing (CAD/CAM), the CAM process requires long hours of tool path programming and debugging. It would also take a long time to calculate (sometimes several hours) the tool path for complex athletic footwear. In order to reduce the tool path editing and programming time, this paper proposes the use of CAPP to reduce processing time and increase efficiency. It is difficult, if not impossible, to develop a generic CAPP system that can generate a process plan to solve general production problems. However, it is quite possible to capture the domain knowledge of a certain production process and embed that knowledge into a CAPP system. We prove, by using such a system, that a very complicated process planning problem can be overcome by a knowledge-based CAPP approach. With such an approach, the traditional manufacturing process of shoe molds can be converted to an automatic manufacturing process with the CAPP system. In fact, shoe molds for real production have been created using the developed CAPP system, demonstrating the effectiveness of this approach. In this paper, we show that several complex and different shoe molds and their machining strategies were automatically planned by the proposed CAPP system. The result of a comparison between the CAPP system with the traditional approach is presented and discussed.     

基于计算几何的曲面造型方法研究

以Pro/Engineer和UGNX为代表的计算机辅助设计和辅助制造软件,在制造行业已经成为产品设计和产品制造工程师的重要工具。这些CAD/CAM软件都必须能够胜任曲面造型的功能,它是产品三维设计的必然前提,因此曲面造型成为计算机辅助几何设计和计算机图形学的一项研究重要内容,而计算几何正是对曲面造型进行研究的数学方法。通过对曲面造型和计算几何的相关概念的介绍,详细阐述了基于计算几何方法建立曲面参数曲线的各种数学建模过程。这些数学建模方法能为各种CAD/CAM系统实现曲面功能提供理论指导。     

基于CAD模型的鞋楦数控刀位点算法

分析了现有鞋楦数控加工方法及其特殊性,提出了一种基于刀具和鞋楦CAD模型,采用三维离散化求最小距离的方法,解决了鞋楦数控加工刀位计算困难的问题.该方法主要步骤如下:(1)建立鞋楦和刀具的三维CAD模型;(2)规划优化的刀具路径轨迹;(3)计算各个刀位点.实践证明该方法快速、准确的生成所需的鞋楦加工刀位.     

考虑二元Copula统计量的晶圆制造叠加误差监测

目前,大多数晶圆制造研究集中在基于离散数据的缺陷模式识别上,而芯片的光刻制造是连续叠加过程,因此基于连续数据的晶片重叠误差监测具有挑战性和必要性。在数据监测过程中充分考虑数据的可解释性,同时结合晶圆数据特性及其物理意义加入新的惩罚项,改进LTS-SPCA降维模型,提出了灵活度较高的稳健稀疏主成分分析技术;然后基于Copula的置换对称、反射对称两种性质,考虑晶圆的几何特征,建立了最佳多元耦合统计量,用于监测晶圆制造的叠加过程异常。所提方法监测异常数据的准确率可达91.75%,具有较高的工程应用价值。     

基于包络法的鞋楦表面点三维反求

鞋楦曲面的检测法采用近似求解获取鞋楦曲面数据,误差大,易导致楦面变形。利用包络法原理反求鞋楦表面数据点,将触测轮在鞋楦表面的滚动测量视为刀具对鞋楦的反复加工过程,生成的包络面替代鞋楦表面,可大大提高精度,并给出了试验验证。