Automated Generation of Fixture Configuration Design

Author(s):  
Yong Bai ◽  
Yiming (Kevin) Rong

Abstract Flexible fixturing is a necessary aspect of flexible manufacturing systems (FMS) and computer-integrated manufacturing systems (CIMS). Modular fixtures are most widely used in industry for job and small batch production. Computer-aided fixture design (CAFD) has become a research focus in implementing FMS and CIMS. Fixture configuration design is an important issue in CAFD. A review of the current research in CAFD indicates that one major problem impeding the automated generation of fixture configuration design is the negligence of study on fixture structures. This paper investigates fundamental structures of dowel-pin 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 candidates and mount them into appropriate positions on baseplate with an interference checking. A prototype system for automated design of dowel-pin modular fixture configurations is presented in this paper. Fixture design examples are given in the end of the paper.

1997 ◽  
Vol 119 (2) ◽  
pp. 208-219 ◽  
Author(s):  
Yiming (Kevin) Rong ◽  
Yong Bai

Flexible fixturing is a necessary aspect of Flexible Manufacturing Systems (FMS) and Computer-Integrated Manufacturing Systems (CIMS). Modular fixtures are most widely used in industry for job and batch production. Computer-Aided Fixture Design (CAFD) 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 configurations 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 candidates and mount them into appropriate positions on a baseplate with interference checking. A prototype system 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.


Author(s):  
W. Ma ◽  
Z. Lei ◽  
Y. Rong

Abstract This paper presents a computer-aided modular fixture design system: FIX-DES. When fixturing requirements are specified as locating/clamping surfaces and points, a fixture configuration will be automatically generated by (1) selecting fixture elements from a fixture element database to form fixture units based on fixture element assembly relationships and (2) placing the fixture units and elements into position on a baseplate while the fixturing requirements and assembly relationships (e.g., hole alignment) are maintained. The fixture element assembly relationships can be automatically established when the geometric models and fixturing functions of the fixture elements are specified so that the FIX-DES system can be easily applied to different fixture systems. The system also provides the interactive design and design modification functions for human expert involvement. The system was developed with core programs in C/C++ and interface programs in a specific CAD environment. The system has been successfully applied in industry and can be easily transferred to other CAD systems. The overall structure of the FIX-DES system is introduced in the paper. The development of the automated fixture configuration design (AFCD) functions are presented in detail. Finally a fixture configura-tion design example is given to illustrate the application of the system.


Author(s):  
Paul C. Xirouchakis

Abstract “Entity-life modeling” (ELM) is a general method for the modeling and design of concurrent software. One area where it can applied is for the control software for flexible manufacturing systems (FMS). The application of ELM allows the integration and overall control of the operation of the numerically controlled machinery, the material transportation and storage facilities into automated factories within the context of computer integrated manufacturing (CIM). The development of flexible manufacturing has been hampered by the lack of such a general approach to FMS software design. ELM is based on the principle that processes and objects in the software are patterned after concurrent “threads of events” and objects in the problem domain. A job in an FMS represents such a thread with events such as “pick from storage”, “place on stand”, etc., which all occur sequentially and with certain time intervals. Several job threads are in progress simultaneously as different jobs are being processed. In the software, a thread of events is represented by a process, such as an Ada task. The direct coupling between the analysis and an efficient control-system software implementation is an advantage over other analysis models, such as Petri nets. A simple FMS is used as an example. It consists of a storage facility and a number of numerically controlled workstations. A conveyor belt is used for the transportation of parts between storage and workstations and between workstations.


Author(s):  
J R Dai ◽  
A Y C Nee ◽  
J Y H Fuh ◽  
A Senthil Kumar

In the development of a modular fixture design system, it is essential to have a modular fixture element database that can be integrated with a CAD system, in addition to the other considerations such as fixture configuration, interference checking, etc., which are also important to fixture designers. This paper describes a new method to create the fixture element database and model the fixturing towers (i.e. subassemblies). By using this method, the database can be effectively created and is easy for use in fixture assembly. The modular fixture tower database is used to represent the subassembly of fixtures. This will simplify the fixture design and assembly process. A built-in interference checking methodology is embedded in the planning stage that will ensure a collision-free fixture design. The system is developed using the knowledge- based system, ICAD, and interfacing with UG-II for modelling the workpiece. Examples of fixture design generated by the system are also provided to illustrate the development.


1990 ◽  
Vol 90 (6) ◽  
pp. 12-16
Author(s):  
Yunus Kathawala

Several examples of successful expert systems applications are presented. Examples of expert systems as applied in process planning, operations planning, inventory control, process design, quality control and scheduling are covered, and the performance of these expert systems is described. Expert systems will become an essential part of computer‐integrated manufacturing (CIM) and flexible manufacturing systems (FMS) because they can perform several of the tasks mentioned above.


1997 ◽  
Vol 119 (4A) ◽  
pp. 593-602 ◽  
Author(s):  
Wayne Cai ◽  
S. Jack Hu ◽  
J. X. Yuan

Fixtures are used to locate and hold workpieces during manufacturing. Because workpiece surface errors and fixture set-up errors (called source errors) always exist, the fixtured workpiece will consequently have position and/or orientation errors (called resultant errors). In this paper, we develop a variational method for robust fixture configuration design to minimize workpiece resultant errors due to source errors. We utilize both first-order and second-order workpiece geometry information to deal with two types of source errors, i.e., infinitesimal errors and small errors. Using the proposed variational approach, other fundamental fixture design issues, such as deterministic locating and total fixturing, can be regarded as integral parts of the robust design. Closed-form analytical solutions are derived and numerical examples are shown. By employing the nonlinear programming technique, simulation software called RFixDesign is developed. This paper presents a new procedure for robust fixture configuration design that contributes especially to fixture designs where deformation is not influential.


Author(s):  
Brahim Bouzouia

This paper presents an  innovative Multi-Agent approach related to an advanced real time control  of flexible manufacturing systems. The proposed architecture is based on the paradigm of Distributed Intelligence and Multi-Agent Systems. The developed  Multi-Agent prototype system integrates  the following functions: Scheduling, dispatching, monitoring and error handling. A new negotiation protocol for manufacturing systems is presented in this paper. The purpose of this protocol is to assign dynamic operations to the resources of the Manufacturing System in order to accomplish the proposed tasks. This protocol is able to deal with exceptions.  


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