Design of automatic parting in calibrator CAD for plastic profile extrusion dies via feature recognitions

A method to deal with the design of automatic parting in calibrator computer-aided design (CAD) for plastic profile extrusion dies via feature recognitions is presented. An integral design method to design all the calibrator plates simultaneously is presented. The approach to automatic parting in calibrators is proposed. For a given calibrator integral plate, the positions of calibrators’ parting faces are identified automatically based on recognitions of the visibility, attribute adjacent graphs of calibrator cavity surfaces. To meet the machining process requirements of calibrators, a parting process to achieve the final position of the calibrator parting faces is presented. A case study is presented to validate the proposed methodology.     

DESIGN TECHNOLOGY FOR INJECTION MOLD PARTING SURFACE BASED ON CASES AND KNOWLEDGE

On the basis of the comprehensive analysis about the automatic generation of the injection mold parting surface,the parting surface design method which introduces knowledge and case-based reasoning (CBR) into the computer-aided design is described by combining with the actual characteristic in injection mold design,and the design process of case-based reasoning method is also given.A case library including the information of parting surface is built with the index of main shape features.The automatic design of the mold parting surface is realized combined with the forward-reasoning method and the similarity solution procedure.The rule knowledge library is also founded including the knowledge,principles and experiences for parting surface design.An example is used to show the validity of the method,and the quality and the efficiency of the mold design are improved.     

多自由曲面产品注塑模具分型线的自动确定

为有效地确定多自由曲面产品模具分型线问题,提出了一种将特征识别技术和有限元方法相结合的模具分型线确定方法。在该方法中,首先,提出了基于图的特征识别方法来对产品中的侧凹特征进行识别,并在识别的基础上对产品模型进行简化;然后,提出了基于有限元的离散方法,对简化的产品模型的所有组成面进行离散,并根据网格面的可视性来判别组成面的可视性;最后,将产品中的所有组成面分成可视面组、不可视面组和退化面组,并通过抽取可视面组或不可视面组的最大边环来确定模具的分型线。研究实践表明,通过该方法可以有效地解决多自由曲面产品模具分型线的确定问题,提高模具设计的效率。     

CAD APPROACH FOR PLASTIC MOULD PARTING DIRECTIONS OPTIMIZATION

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Recognition of undercut features and parting surface of moulded parts using polyhedron face adjacency graph

An injection or die-casting mould is an assembly of parts containing an impression into which molten material is injected. In this article, the undercuts present in mould parts are divided into basically two parts: completely visible and partially visible. A graph-based approach is proposed to identify these undercuts even for the free form objects. Unlike conventional graph based methods a new polyhedron face adjacency graph (PFAG) is proposed with the key concept of visibility of undercuts by using Bezier surface. A rule-based approach is also discussed to automatically generate an optimal parting surfaceof irregular moulded parts. Since the generation of parting surface plays an important and effective role in mould – die design, thus it is essential to develop a simple and robust algorithm based on proposed methodology, which can effectively tackle the problem. Different case studies show that the proposed method can recognize various undercut features without much difficulty.     

注塑模具分型线自动搜索技术研究

提出了一种自动搜索模具分型线的方法。该方法首先依据脱模方向确定与之垂直的平面 ,并将塑料制件向该平面投影 ,得到模具分型线的主轮廓线 ,然后建立主轮廓线与制件表面上的边线和顶点投影映射关系 ,从中可以得到多种候选分型线 ,最后根据分型线的评价因子计算各分型线的优化目标函数值 ,确定最佳的分型线。实例测试表明 ,该方法具有较高的效率和实用性。     

基于Pro/E利用自动分型面技术创建模具型腔研究

简要介绍了Pro/E自动分型面技术,详细介绍了自动分型面形成操作步骤,并成功利用分型面创建了模具型腔;对分型面作了简要分析,利用自动分型面技术可以快速而准确的创建分型面,提高了设计效率.     

一种模具脱模方向自动判定及优选算法

提出一种自动判别模具脱模方向的算法。该算法以基于图的特征识别所获得的特征作为研究对象,通过特征间可视性分析运算来判断零件潜在的脱模方向,引入脱模方向判定原则,最终确定出脱模方向。该算法可解决存在多特征复杂零件脱模方向的判定问题,不但可以获得最优脱模方向,还可得到侧凹特征的相关信息。在UG平台上开发的自动脱模方向判别系统,提高了模具设计中该环节计算的效率和精度,为模具设计后续工作提供可靠保障。     

基于事例推理的模具分型面设计方法研究

在全面分析分型面自动设计方法的基础上，提出了基于事例推理的注塑模分型面设计方法，给出了基于事例推理的分型面设计总体框架。运用特征造型技术进行塑件三维建模，以主形状特征为索引构建了含有分型面信息的塑件事例知识库。采用正向推理策略与相似性求解相结合的方法，实现了模具分型面的自动推理设计，给出了分型面位置设计的推理方法与流程，提高了模具设计的质量和效率。     

基于UG NX 6.0 Mold Wizard的侧向抽芯直接分模方法

针对一需侧向抽芯的塑件,在UG NX 6.0中的Mold Wizard模块中,准确设置分型线,合理将分型面进行组合,快捷巧妙生成型芯、型腔及侧抽芯等,从而获得了实际应用的操作方法。使用该分模技术,有利于降低分模难度,提高模具设计精确度,掌握Mold Wizard分模的特点,为模具设计人员提供便利。     

Image processing-based accessibility analysis method for determining undercut-free parting direction

In injection molding, demoldability of a part without the use of a side core is possible only if all of its surfaces are fully accessible in the parting direction. A mold surface may be fully accessible from some directions, but may not be accessible from other directions. Therefore, to determine the undercut-free parting direction, an algorithm is developed that evaluates the accessibility of each part surface from a set of directions (called as candidate parting directions) by using image processing techniques. In the proposed methodology, the surface accessibility is determined by comparing the projected area of each surface on the image plane in the presence of other part surfaces to that of the same surface in the absence of other part surfaces. The algorithm can be used to determine the accessibility of planar, ruled, and free-form surfaces without tessellating the part surfaces. The algorithm includes a method that can also successfully classify surfaces that are oriented perpendicular to the parting direction. The surface classification can be used to identify the undercut-free parting direction, recognize the various undercut features, and form the visibility maps. The accuracy of the algorithm depends upon the number of pixels used to represent the part on the computer screen. The method has been successfully implemented, and test results are discussed in this paper.     

Feature extraction from freeform molded parts for moldability analysis

In the design of plastic injection molds, the depressions and protrusions (DP) preventing the removal of molded part from mold are referred to as undercuts. This paper describes an approach to recognize DP feature within the curvature region representation based on the curvature properties of entities in B-rep model. The recognized depression features and the concave transitions between protrusion features are potential undercuts which affect the choice of parting directions of the molded part. The possible withdrawal directions of the potential undercuts are derived by geometric reasoning and visibility map computation. This method can recognize isolated and intersecting features with planar, quadric, and freeform surfaces. The identified potential undercuts with their possible withdrawal directions can provide decision support information for mold design such as selecting parting direction, parting lines and surfaces, etc. The case study is presented to verify the feasibility of the developed method.     

Algorithm for automatic parting surface extension in the mold design navigating process

This study focused on the planning and development of an algorithm and process for automatic parting surface design under the CAD software architecture. Relating to the smooth opening of a mold, the parting surface is an important step of mold design. The parting surface can be categorized into the main parting surface and the shut-off parting surface. This study developed an algorithm of extension rules for the main parting surface and determined the contour vector and geometric relationship via computer software. It can realize the main parting surface automatic extension and can be embedded into a web-based mold design navigating process. Through a standardized design process, it can reduce the number of mouse clicks by 90%, enabling users to rapidly complete mold designs, reduce design errors, and improve efficiency.     

往复式骨架油封模具自动化设计技术研究

针对骨架油封模具设计周期长的问题,通过对往复式骨架油封进行研究,以模具设计为出发点,对模具中关键分型线的确定方法进行了研究,并分析了余胶槽、顶杆和相关壁厚等关键地方的变形规律,建立了数学模型。采用自顶向下的建模方法对模具总体装配及零件进行建模,依据模具设计规则,从油封三维模型的几何特征中提取构成模具型腔的各个零件及其分型线的关键特征,形成封闭的型腔特征曲面,进而利用这些特征曲面切除装配结构中的各个模板零件内侧特征,获得模具型腔结构特征,完成模具详细设计。该设计方法实现了骨架油封模具随油封尺寸自动变形设计,大大提高了设计效率。     

电热壶体的注射模设计

在注塑模具中，分型面的设计将直接影响模具的复杂程度和制造成本，并对产品的质量产生影响。以PRO／MOLDESIGN软件包为工具，通过对电热壶体的结构和工艺性分析，比较详细地论述了电热壶体模具分型面的设计考虑因素，并阐述了在PRO／MOLDESIGN上快速生成模具型芯、型腔的方法。     

壶体注塑模设计

在注塑模具中分型面的设计将直接影响模具的复杂程度和制造成本,并对产品的质量产生影响。以PRO/MOLD-ESIGN软件包为工具,通过对电热壶体的结构和工艺性分析,较详细地论述了电热壶体模具分型面的设计,并阐述了在PRO/MOLDESIGN上快速生成模具型芯、型腔的方法。     

汽车铝合金轮毂低压铸造模具设计

本文分析了低压整体式铝合金轮毂的低压铸造工艺性,并从铸型分型面、铸型不期而遇腔尺寸和铸型壁厚的确定,铸型排气系统、浇注系统、冷却系统的设计等几方面介绍了该产品模具结构设计要点。     

Pro／E中“裙边分型面”法分模思路探讨

Pro／E中裙边分型面法对于复杂的塑胶产品的分模是一种较好的设计方法,通过对裙边分型面分模思路的探讨,可以明确裙边分型面法的分模原理,进而明了裙边分析面分模的流程,结合塑胶模具设计的专业知识．可以快速的设计出合理的模具分型面。裙边分型面分模的基本思路就是主分型面（外围分型面）使用裙边分型面快速的创建,破孔分型面则根据模具结构要求可以通过基本做曲面的方法完成内部的分型面。     

面向制造的曲面设计系统

为了支持面向制造的曲面设计,提出了一个基于计算机辅助设计／计算机辅助制造系统的嵌人式计算平台,该计算平台主要包括约束信息建模和可制造性分析2个功能模块。通过对曲面可制造性判据的抽象,建立了应用信息模型,用于从曲面几何形状中提取制造约束信息。应用于曲面加工问题,给出了根据约束信息计算可行刀具方向的具体方法。面向模具零件分型曲面的设计,建立了可制造性分析工具。针对一个雕塑曲面零件设计实例,通过对模具分型方向和加工约束进行分析,给出了可行的分型曲面设计结果,验证了所提出的曲面可制造性分析方法的可行性。     

基于UG的注塑模具设计分模方法

UG的注塑模具设计过程是类似的,但作为模具设计最重要的一个环节分模却是灵活多变的。以风扇叶塑件为例,介绍了分模的基本原理,阐述了基于UG的自动分模与手工分模方法的分模过程,两种方法的灵活运用可大大提高注塑模具设计的效率。