Computer-aided Fixture Design System Research Articles

Development of locating system design module for freeform workpieces in computer-aided fixture design platform

Development of an efficient computer-aided platform for fixture design requires intelligent algorithms to be developed as decision making tools for different designing functions. Locating system design is among the representative fixture design functions which are in need of such intelligent algorithms to implement their complicated roles. This rather unmet need has already hampered the development of automated computer-aided fixture design systems. The authors have proposed an analytical and algorithmic locating system design procedure as a part of their continuous effort to establish a PythonOCC-based platform, which is the subject of the present paper. In order to surmount the geometrical restrictions, workpieces with freeform geometries of NURBS types have been taken into consideration for locating system design. Constraining workpiece’s degrees of freedom, capacity of locating surfaces in bearing the machining loads, and ease of workpiece loading and unloading into and from the fixture together with some other checking rules constitute the characteristic criteria of the proposed analytic procedure. The proposed procedure has been employed for several workpieces with freeform geometries to evaluate its efficacy.

AN INTEGRATED RBR FIXTURE DESIGN SYSTEM

Traditionally fixture design processes are costly and time-consuming when carried out manually. To try to reduce the negative features, we are creating a computer-aided fixture design system, integrated in the SolidWorks’ environment. This system uses rule-based reasoning in the form of If-Then-Else rules, incorporated in its VB.NET code. This paper presents our progress in the form of an interactive add-in program for locating parts. This program generates modular fixtures for locating prismatic or cylindrical parts, using rules and mathematical equations. Its usage can shorten the time needed for determining the type and position of every module of the fixture, their assembling, and inspection.

Development of a computer-aided fixture design system for lightweight grippers in the automotive industry

The need for dedicated fixtures for flexible manufacturing systems is increasing, as dedicated fixtures are lighter, more compact, and more accurate than flexible fixtures. The main challenges are that parts and processes are becoming more and more complex, which requires designing novel or complex dedicated fixtures, and that, for one given flexible fixture to be replaced, several variants of such dedicated fixtures must be designed to hold a variety of individual parts, without causing increased costs and delays. The systematic fixture design method and computer-aided fixture design system (CAFDS) developed and applied for the presented industrial case - novel design of a lightweight (carbon fibre composite) robot gripper - is a possible approach to addressing these issues.

A knowledge reuse-based computer-aided fixture design framework

Purpose – Fixture design is a complicated task requiring both intensive knowledge and experience. This paper aims to present a computer-aided fixture design (CAFD) system framework based on design reuse technology. Design/methodology/approach – Fixture design domain ontology is constructed by analyzing fixture design document corpus. A design reuse engine is proposed to realize fixture design knowledge retrieval and fixture model retrieval based on ontology and find fixture design cases similar to fixture design problem, and then use evolutionary methods to modify the retrieved model to meet the design requirements and then generate a new fixture. Findings – The paper finds that the proposed framework is an efficient tool to improve efficiency of fixture design. Practical implications – Fixture design existing experience and cases can be used efficiently reused and to advance new fixture design processes. Originality/value – This paper presents a CAFD system framework capable of carrying out fixture design through full using of the existing fixture design resource and experienced knowledge.

A review of computer-aided fixture design with respect to information support requirements

This paper lays the foundation for an integrated representation for advanced computer-aided fixture design (CAFD) systems through a systematic comparative analysis of the existing CAFD systems. Significant work done in the CAFD field, the different methods used for each design phase, their working principles, and the information modeling requirements are presented. Information flows are developed through identification of CAFD phases (problem definition, fixture synthesis, and fixture analysis), of the effective methods for each, and of their input/output traffic. This survey is used to establish the representation and information requirements for integrated CAFD leading to a novel representation scheme. Specifically, the information types required include geometric information, locator information (number, type, orientation, and position), material properties, machining information (tool paths), applied forces, tolerance requirements, and displacement (errors).

Fixture design information support for integrated design and manufacturing

Although a vast amount of research has been conducted on developing computer-aided fixture design systems, the need for information exchange between the fixture design domain and other manufacturing domains has not been thoroughly dealt with. This paper addresses this gap in fixture design research through the development of appropriate information models for computer-aided fixture design systems to support integrated design and manufacturing. A fixture design activity model is presented that relates fixture design to other design and manufacturing activities. The implementation of the information models in XML and the exchange of the information models based on an XML messaging approach are also discussed.

Immobilization check for fixture design

Fixture design contributes highly to manufacturing safety and quality. Computer aided fixture design (CAFD) facilitates more cost effective and efficient workholder design. However, heuristic and case-based approaches are still common. This paper addresses CAFD using the computational geometry approach. The correctness of a fixture design will be determined through vector-theoretic immobilization checking of the fixture points (i.e. location and clamping points) proposed. Details of the translational and rotational immobilization checking theory are explained, which are also applicable to general three-dimensional shapes. In real life, perfect geometry does not exist. As contemporary CAFD systems cannot cater for non-ideal geometry satisfactorily, the paper also develops an interval analysis scheme for toleranced immobilization checks. A real-life case study is presented to demonstrate the procedure.

Static and dynamic models for predicting the effects of supports on machining flatness and roughness

This paper presents analytical static and dynamic models of a rigid workpiece held in a machining fixture in contact with locators and clamps (in a 3-2-1 scheme) and three supports (in three locating planes) influenced by machining forces and moments. The model is used to predict the effects of support parameters including the support position, rigidity and preload on improving machining accuracies. Milling and creep feed grinding experiments are performed to verify the model. The model can be used to develop present computer aided fixture design systems that consider only locators and clamps in a force analysis module.

Computer-aided fixture design system for comprehensive modular fixtures

Fixture design plays an important role at the planning stage before shop-floor production. A desired fixture design can be employed to hold the workpart securely so that slippage and excessive deformation can be prevented during machining. Therefore, appropriate fixturing contributes highly to machining quality. To reduce lead time and the human effort devoted to fixture planning, computer-aided fixture design (CAFD) is required. In this paper, a CAFD system consisting of three modules, i.e. Fixture Data Management, Fixture Element Selection and Fixture Layout Design, is developed. According to fixture feature recognition and classification, a comprehensive fixture database in the Fixture Data Management module is constructed to maintain efficiently the fixture-related data. The domain of the fixture database consists of modular mechanical fixtures, modular hydraulic fixtures and modular V-blocks. After expertise extraction, suitable fixture elements can be automatically selected according to the machining conditions in the Fixture Element Selection module. Finally, by integrating previous reasoning algorithms, fixturing locations and orientations are determined. Feasible fixture layouts that meet manufacturing and inspection specifications can be generated in the Fixture Layout Design module. The prototype system is implemented under commercial CAD and database management system (DBMS) software. Comprehensive fixture databases and a rule-based knowledge base are built to provide effective data management. The paper aims to propose a systematic CAFD framework and application system to provide efficient decision support for different types of fixture planning.

A Fast Interference Checking Algorithm for Automated Fixture Design Verification

Fixtures are tooling devices used to locate, support and hold workpieces during a manufacturing process. The major purpose of a computer-aided fixture design (CAFD) system is to provide a fixture design based on fixturing principles and workpiece information. Interference checking between the machining tool and fixture units, as well as between fixture units, is one of the important functions of automated fixture design. This paper presents a fast interference checking algorithnt for automated modular fixture design validation. It is based on the study of the geometric characteristics of modular fixture components and the machining tool. The fixture component model is simplified into a 2D contour model with height information. The tool-path model is represented by a moving dot for 3-axis operations, or a moving line segment in 5-axis operations, as the fixture component model is expanded according to the tool radius. The method is different from the popular collision detection procedure using swept volume and is more efficient for fixturing verification. Application of this method will greatly reduce the computation complexity for fixturing interference checking. The method is implemented with a CAFD system. An example is given at the end of the paper.

Computer-aided fixture design: a review

Abstract This paper reviews some of the current developments in computer-aided fixture design (CAFXD), and proposes directions for future research initiatives. The literature has indicated a growing interest in the development of computer-aided fixture design systems. The motivation for this manufacturing research is stimulated by the desire to reduce setup and production costs, and the potential rewards of automation. Most of the papers published have centred on the micro aspects of fixture design that addressed singular problems; but as the research matures, more systems will be directed towards an integration with other computer-aided engineering tools for total fixture design. In this paper the recent developments in CAFXD and projections for emerging systems are presented.

Fixturing Feature Recognition for Computer-aided Fixture Design

Flexible fixturing is an important issue in flexible manufacturing systems (FMS) and computer-integrated manufacturing systems (CIMS). Application of modular fixture systems is a solution of flexible fixturing. One difficulty in applying modular fixtures is the complexity of their design and assembly. This paper presents a group technology (GT) based computer-aided design (CAD) system for modular fixture designs. A new coding system with fixturing information is proposed for identifying fixturing features of the pan. Based on the concept of GT, a fixture design database is developed to acquire and accumulate expert knowledge, and to retrieve the fixture designs made by experienced people for a new fixture design. A user fixture component database can be used to generate fixture designs and a graphics output including a fixture component list. Compared with other fixturing CAD systems in literature, this is an application-oriented CAD system for industry, which can be used to deal with complex fixturing problems. In this paper, GT based identifications of fixture features are emphasized, and the structure of the computer-aided fixture design system is introduced. An implementation example is presented.