Automated setup and fixture planning system for box-shaped parts

The topic of the research is related to the domain of computer-aided manufacturing process planning. This paper deals with the problem of setup and fixture planning for the machining of box-shaped parts on the horizontal machining centres. The setup and fixture planning involves the definition of setups, the setup sequence and conceptual design of fixtures for each setup. The central topic of this research is the automation of the conceptual design of fixtures. This topic is interconnected with the setup planning, and accordingly, the aim of the author has been the integrated handling of tasks of setup and fixture planning and the finding of solution in an integrated system. Based on the workpiece model, the developed system automatically determines the setup sequence, the content of setups and the conceptual solution of fixture for each setup. The paper presents the problems of fixture solutions and the partial tasks of workpiece holding, the typical solution of partial tasks and the conditions of their application and finally offers a new method, which makes the integrated handling of tasks of setup and fixture planning and finding solution in an integrated system possible.     

基于图的夹具特征识别方法研究

夹具特征识别是实现夹具自动化设计的基础。本文在属性邻接图的基础上,给出了一种通过几何推理实现夹具特征识别的方法。在该方法中定义了制造特征方向,并通过最大凹边凝聚的方法,实现了极限表面的识别,在此基础上通过一系列几何推理算法来识别夹具特征。该方法可以有效地解决CAD与夹具设计CAD之间的集成问题,为自动化夹具设计探索了一种新的途径。     

Automatic recognition of intersecting features for side core design in two-piece permanent molds

The automatic recognition of molding features (protrusions, depressions, and their intersections), core, and cavity surfaces plays an important role in shortening the lead time in mold design and manufacturing as well as aiding the side core design. Consequently, in this paper, an automatic mold feature recognition system to recognize protrusion, depression as well as intersecting depression features is proposed and implemented. The recognition of various types of intersecting features is a significant contribution to the literature. The output generated by the accessibility analysis (without discretizing the part) is used as the input to the feature recognition module. The newly developed system is assessed by comparing its results with those of earlier systems. A comprehensive case study is presented that can demonstrate the additional capabilities of the proposed system to those of the present in the published literature.     

Development of Automated Fixture Planning Systems

Fixturing is an important manufacturing activity. The computeraided fixture design technique is being rapidly developed to reduce the lead time involved in manufacturing planning. An automated fixture configuration design system has been developed to select automatically modular fixture components and place them in position with satisfactory assembly relationships In this paper, an automated fixturing planning system is presented in which fixturing surfaces and points are automatically determined based on workpiece geometry and operational information. Fixturing surface accessibility, feature accuracy, and fixturing stability are the main concerns in the fixture planning. The system development, the fixture planning decision procedure, and an implementation example are presented in the paper.     

特征在加工过程中的变异性研究

从加工工艺角度分析特征在加工过程中的演变规律。提出了变异特征的概念,探讨了变异特征在结构、属性、类型等方面的变特点。给出了变异特征属性邻接图和边面关联矩阵, 表达了变异特征组成成面之间的有机联系。通过一般产品上特征的变异性定义,实现了基于变异特征的零件建模,并在夹具安装规划自动设计系统中初步应用,得到了较理想的夹具装夹方案。     

基于相交特征信息建模及其提取技术的研究

针对相交特征的自动工艺规划算法对产品制造信息的需求,研究了基于特征的自动工艺规划算法对特征几何属性和工艺属性信息的需求关系,提出了一种针对相交特征制造工艺决策的产品信息模型。以虚面信息作为搜索相交特征相关信息的驱动信息,建立由虚面信息索引层、相交特征索引层、基本制造信息层三个层次的信息所构成相交特征制造信息模型。通过对基于特征基面的制造特征自动识别算法的研究,以一个应用实例对相交特征制造信息的获取过程进行解释,表明了基于相交特征的制造信息模型的实用性和有效性。     

定位基准的自动优选原理与算法

为了在CAD CAPP自动系统中确保加工精度 ,研究并导出了特征综合定位能力计算的量化公式。给出了系统算法流程图。解决了特征与面的信息转换和数据结构等问题。在夹具安装规划系统FSPS上成功实现了定位面的自动优选和细分     

加工余量的自动确定

为使机床夹具自动设计系统能够快速、准确地自动确定加工余量,分别对影响加工余量的八种因素作了详细的分析和推导,给出了一套实用、准确的计算公式,并成功地应用于夹具安装规划自动系统.     

A STEP AP 203–214-based machinable volume identifier for identifying the finish-cut machinable volumes from rough-machined parts

This paper presents a STEP AP203–214-based machinable volume identifier (MVI) to identify the finish-cut machinable volume in prismatic parts by deducting the rough-machined part from the final part. The MVI provides an intermediate link between rough and finish machining computer-aided process planning system for automatic generation of process plans while machining prismatic parts. To calculate the machinable volumes of manufacturing features, the MVI utilizes the output of the feature identifier which contains the information about the dimensional details, edge loops, edges, vertices, coordinate points, and location planes of the features. In this research, a total of 234 features have been considered; out of which, 32 are normal and 202 are tapered. To calculate the machinable volumes for these features, generalized methodologies are developed for 17 basic feature types, each having a varying number of specific features. Initially, the pattern strings are generated for the front and back face of the rough-machined feature and final feature. Then, MVI uses the predefined syntactic pattern strings stored in the strings database and checks with the generated strings of the feature to determine the shape of the machinable volume stored in the volumes database. After determining the shape, one relevant methodology or more (for features having combination of more than one taper) are selected from among the 17 “feature type” specific methodologies developed for finish-cut machinable volume identification. In this article, methodology is presented for one basic feature type which covers 14 features and explained through one case study. The final output from this module is stored as a text file with full dimensional details of machinable volumes for later use inside the machining planning module. The proposed MVI can be used in Computer Integrated Manufacturing Industries as an intermediate linker to achieve a robust manufacturing environment.     

Process Planning Using Adjacency-Based Feature Extraction

The use of attributed adjacency (AA) feature recognition can encapsulate the engineering significance of a part and represent it as a matrix or an arc-node graph. This creates a feature recognition technique that involves scanning a matrix or graph for a combination of zeros (concave relationships/edges) and ones (convex), or smaller arc-node graphs that are predetermined to be features. AA techniques have often suffered problems when dealing with feature interactions, as a feature found must be exactly matched with those stored. This paper presents a modification of the AA matrix and employs a new concept for identifying features and the application in developing software for process planning. A unique feature taxonomy is described, which when combined with the new feature identification system creates a feature recognition and extraction system that includes curved surfaces and eliminates the need for separating interacting primitive features. The new system takes its input from neutral STEP files and produces a list of features with complete information for process planning. cycle, and so automatic feature recognition has its place in manufacturing. ID="A1"Correspondance and offprint requests to: R. Ibrahim, Faculty of Engineering, Monash University, Caulfield Campus, 900 Dandenong Road, Caulfield East, 3145 Victoria, Australia. E-mail: raafat. ibrahim@eng.monash.edu.au     

基于制造资源能力的装夹工艺分层设计技术

为发展创成式的计算机辅助工艺设计,研究了计算机辅助工艺设计系统中工件装夹规划的自动生成算法.基于扩展有向图,建立了零件的公差信息和基准-加工特征关系的数学表示模型,基于公差分析和制造资源能力模型,建立了从单件层到多件层的工件装夹工艺生产算法.该数学模型和算法可自动识别工件的加工特征、装夹基准,并根据制造资源能力和公差分析对装夹进行优化分组,实现装夹分组对工件加工精度的影响最小化,进而生成装夹规程.最后以实例证明了该方法的可行性.     

A setup planning methodology for prismatic parts considering fixturing aspects

Setup planning is an important part of process planning that has been widely investigated by various researchers. However, the output of the traditional setup planning approaches is limited and insufficient for the upstream process planning activity, fixture design. In this work, a setup planning system is developed that provides sufficient inputs to the fixture designer in terms of recommended depth of cut and feed, fuzzy clamping forces, near optimal locator and clamp layout, and sizes of the locators and clamps. The fixture designer can further optimize the fixture plan by taking these inputs. The methodology is illustrated with the help of an example.     

Computer aided manufacturing planning for mass customization: part 2, automated setup planning

Setup planning plays a crucial role in CAPP to ensure product quality while maintaining acceptable manufacturing cost. The tasks of setup planning include identifying manufacturing features and corresponding manufacturing processes, determining the number of setups, part orientation, locating datum and process sequence in each setup, and selecting machine tools and fixtures. An automated setup planning technique and system has been developed based on not only the tolerance analysis, but also the manufacturing resource capability analysis. The automated setup planning is divided into two levels: setup planning in single part level and in machine station level. Algorithms for setup generation and process sequencing have been developed and a case study of setup planning is presented.     

An intelligent process planning system for prismatic parts using STEP features

This paper presents an intelligent process planning system using STEP features (ST-FeatCAPP) for prismatic parts. The system maps a STEP AP224 XML data file, without using a complex feature recognition process, and produces the corresponding machining operations to generate the process plan and corresponding STEP-NC in XML format. It carries out several stages of process planning such as operations selection, tool selection, machining parameters determination, machine tools selection and setup planning. A hybrid approach of most recent techniques (neural networks, fuzzy logic and rule-based) of artificial intelligence is used as the inference engine of the developed system. An object-oriented approach is used in the definition and implementation of the system. An example part is tested and the corresponding process plan is presented to demonstrate and verify the proposed CAPP system. The paper thus suggests a new feature-based intelligent CAPP system for avoiding complex feature recognition and knowledge acquisition problems.     

Integrated setup planning and operation sequencing (ISOS) using genetic algorithm

Process planning is an essential component for linking design and manufacturing process. Setup planning and operation sequencing are two most important functions in the implementation of CAD/CAPP/CAM integration. Many researches solved these two problems separately. Considering the fact that the two functions are complementary, it is necessary to integrate them more tightly so that performance of a manufacturing system can be improved economically and competitively. This paper presents a generative system and genetic algorithm (GA) approach to process plan the given part. The proposed approach and optimization methodology analysis constraints such as TAD?(tool?approach?direction), tolerance relation between features and feature precedence relations to generate all possible setups and operations using workshop resource database. Tolerance relation analysis has a significant impact in setup planning for obtaining the part accuracy. Based on technological constraints, the GA algorithm approach, which adopts the feature-based representation, simultaneously optimizes the setup plan and sequence of operations using cost indices. Case studies show that the developed system can generate satisfactory results in optimizing the integrated setup planning and operation sequencing in feasible condition.     

可重组自动装配夹具编码及智能规划专家系统的研究

介绍面向自动装配系统的分类编码用于可重组自动装配夹具智能规划系统的零部件信息输入,对原有的ＶＢ编码系统进行改进,使之便于计算机进行数据处理和面向用户的开放性并提出装配夹具元件编码系统的表示方法,分析可重线与自动装配夹具规划专家系统结构,确定各个组成部分的结构和功能;开发基于面向对象方法地在Ｃ＾＋＋开发平台上建造的可重组自动装配夹具智能规划专家系统。     

孔系组合夹具三维构形自动生成研究

采用ObjectARX语言开发了具有夹具特征和装配特征的参数化的孔系组合夹具元件库,并基于夹具特征和专家系统,建立了一种自动确定定位和夹紧区域的孔系组合夹具构形图自动生成系统,并阐述了有关算法主要思想.     

基于三维特征模型的零件制造信息的提取

从实际应用出发,采用人工辅助识别制造特征、自动提取特征参数的方法,较好地实现了由零件的三维设计模型自动地获取零件的绝大部分制造信息,从而实现了三维CAD系统与CAPP系统的集成。所开发的零件制造信息提取模块在某汽车底盘厂得到应用。     

A Surface Area Calculation and CAPP System for Non-Axisymmetric Deep Drawing Products

In this paper a surface area calculation for non-axisymmetric deep drawing products of elliptical shape was constructed for the design of blank shapes of deep drawing products by using an AutoLISP function in AutoCAD software. A computer-aided process planning (CAPP) system for rotationally symmetric deep drawing products has been developed. In this study, a CAPP system for non-axisymmetric deep drawing products of elliptical shape was constructed using process sequence design. The system developed consists of four modules. The first is the recognition of shape module for recognising non-axisymmetric products. The second is a 3D modelling module for calculating the surface area for non-axisymmetric products. The third is a blank design module for creating an oval-shaped blank with an identical surface area. The fourth is a process planning module based on production rules that play the most important role in an expert system for manufacturing. The production rules are generated and upgraded by interviewing field engineers. The drawing coefficient, the punch and die radii for elliptical shape products are considered as the main design parameters. The suitability of this system was verified by applying it to a real deep drawing product. This surface area calculation and CAPP system should be very useful for reducing the lead-time for manufacturing and for improving the accuracy of products.     

Development of a computer-integrated system to support CAD to CAPP

During the 1990s, Computer-Aided Design (CAD) and Computer-Aided Process Planning (CAPP) have emerged as effective means of improving productivity and efficiency, resulting in widespread research work related to CAD and CAPP integration in the hope of achieving seamless data flow among the relevant computer systems. Unfortunately, the efficiency of process planning systems still needs significant improvement due to the problems of design data loss or design data mis-interpretation. This paper attempts to introduce an intelligent computer-integrated system for reliable design feature recognition in order to achieve automatic process planning. Moreover, it describes a rule-based computer-integrated system for recognizing features of components stored as STEP format, analyzing the design files and designing manufacturing processes. In this approach, the STEP design file is used as the information source for generating detailed manufacturing process. The significance of this research is that the product designs with dissimilar formats from various CAD systems can now be interconnected and automatically coded for multiple manufacturing purposes. It presents an effective method that rule-based reasoning is used to create optimal process plans for metal cutting.