Abstract: Flexible fixturing is a necessary aspect of Flexible Manufacturing Systerm(FMS) and Computer-Integrated Manufacturing Systems(CIMS)，Modular fixture are most widely used in industry for job and batch production. Computer-aided fixture design（CADS） has become a research focus in implementing FMS and CIMS. Fixture configuration design is an important issue in the domain of CAFD. A review of the current research  in CAFD indicates that a major problem impeding the automated generation of  fixture configuration is the lack of studies on fixture structures. This paper investigates fundamental structures of dowel-pin based modular fixtures and fixturing characteristics of commonly used modular fixture elements. A modular fixture element assembly relationship graph（MFEARG） is designed to represent combination relationships between fixture elements, Based on MFEARG, algorithms are developed to search all suitable fixturing unit condidates and mount them into appropriate positions on a baseplate with interference checking.A prototype systerm for automated design of dowel-pin modular fixture configurations is presented in this paper. Fixture design examples are given at the end of the paper.43844

1.Introduction

 Reducing production cycle time and responding to the rapid change of product design is a means of surviving and thriving in the competitive marker for most manufaturing companies. Manufacturing planning,including tooling，makes a major contribution in the production cycle. With the develpoment of CNC technology which makes machining time much shorter than ever，the attempt to reduce manufacturing time is focus on decreasing the time involved in workpiece setup. Flexible fixturing has become an inportant issue in FMS and CIMS. There are several different categories of flexible fixtures such as phase-change material，modular, adjustable, and programmable fixtures where modular fixtures are widely used in industry. Modular fixtures were originally developed for small batch production to reduce the fixturing cost，where the dedicated fixtures were not economically feasible. The flexibility of the modular fixture is derived from the large number of fixture configurations from different combinations of the fixture element which may be bolted to a baseplate. Modular fixture elements can be dis-assembled after pro-cessing a batch of parts and re-used for new parts. Modular fixture configuration design is a complex and highly experience-dependent task. This impedes further applications of modular fixtures. Lack of skillful fixture designer is a common problem in industry. The development of computer-aided fixture design systems is necessary to make manufacturing systems truly flexible

shows an outline of fixture design activities in manufacturing systems, including three steps：setup planning fixture planning, and fixture configuration design. The objective of setup planning is to determine the number of setups needed, the orientation of workpiece in each setup and the machining surfaces in each setup. The setup planning could be a sub-set of process planning. Fixture planning is used to determine the locating, supporting and clamping points on workpiece surfaces. The task of fixture configuration design is to select fixture elements and place them into a final configuration to locate and clamp the workpiece . As more and more CNC machines and machining centers are employed, many operations can be carried out within a single setup , which needs to be ensured by a well designed fixture configuration . This paper focuses on automated fixture configuration design(AFCD).

Some previous research on setup planning can be found in the Computer-Aided Process Planning（CAPP）area[5,6,7] , Most of the research in CAFD area was on fixture planning, including: a method for automated determination of fixture location and clamping derived from a mathematical model[8]; an algorithm for selection of locating and clamping positions which provided the maximum mechanical leverage[9]; kinematic analysis based fixture planning [10,11]; and rule-based systems developed by European researchers to design modular fixtures for prismatic workpieces [12,13]. 夹具结构设计英文文献和中文翻译:http://www.751com.cn/fanyi/lunwen_44890.html