Locating error analysis and tolerance assignment for computer-aided fixture design

Rong, Yi; Hu, Weixin; Kang, Young Jin; Zhang, Y.; Yen, David W.

doi:10.1080/00207540110056243

Cited by 53 publications

(15 citation statements)

References 5 publications

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“…The variance of the position error of the workpiece is minimized and the stochastic characteristic of the locating errors are integrated into the optimization. Rong et al [23] presented a locating error evaluation algorithm with sensitivity analysis functions for the 3-2-1 locating scheme, pin-hole location scheme and V-block locating scheme. The prototype system was applied to two automobile manufacturing companies.…”

Section: Geometry Methods In Fixture Analysis and Verificationmentioning

confidence: 99%

Fixture Feasibility: Methods and Techniques for Fixture Planning

Kang

Peng

2008

Computer-Aided Design and Applications

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Fixture planning is a complex activity restricted by the extreme diversity of workpieces and several environmental factors including machine tools, assembly tools, grasping devices, and cutting tools. This paper reviews methods and techniques for the geometry analysis of fixture feasibility in product development. Fixture synthesis methods including geometrical analysis and fixture assembly planning are surveyed. The implementation of CAD-based and Web-based fixture planning systems is discussed in respect to their reasoning methods, functionality, limits and potentials. A novel fixture planning system is proposed and further research activities are identified. INTRODUCTIONOver the decades, substantial research has been conducted to decrease production cost and processing time in manufacturing to meet the competitive market demand. The workpiece handling system, which largely affects the usability of machine tools, is used to clamp, change and store the workpiece in manufacturing [1]. Fixtures play an important role in workpiece handling. Proper fixture planning can dramatically reduce the manufacturing cost, the lead-time, and labor skill requirements in product manufacturing. Also, the integration of fixture planning with computer-aided design and computer-aided manufacturing (CAD/CAM) provides an overall optimal solution for product design and manufacture. However, fixture planning is a highly experience-based activity. There are not many fixture planning tools available for industry applications due to the extreme diversity and complexity of workpieces. New manufacturing technologies, such as computer-integrated manufacturing, flexible manufacturing systems, lean manufacturing, agile manufacturing and internet-based manufacturing, bring new challenges to fixture planning in terms of the planning theory, planning reliability and planning efficiency. Fixtures are used to locate, hold and support workpieces in manufacturing operations such as machining, inspection, and assembly. A traditional fixture, called dedicated fixture, is designed to hold a specific workpiece. The cost of design and fabricating dedicated fixtures can take up to 10-20% of the total manufacturing system cost. Usually, design and manufacturing of dedicated fixtures are time-consuming due to some workpieces' tight tolerance and restricted machining operations. Flexible and adaptable fixtures dramatically reduce the fixturing cost and lead-time since they are reusable [2]. Using flexible and adaptable fixtures can expect as much as 80% reduction of the fixture cost. Modular fixture, one type of flexible fixtures, is a set of ready-made, re-usable, standard components and combination units. The set includes base plates, supports, locators, clamps and accessories. Modular fixtures provide many fixture configurations for different workpieces by using a variety of fixture element combinations. Much work of fixture planning has been reported based on modular fixtures [3][4][5][6]. Computer-aided fixture planning (CAFP) aims to determine fixture co...

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Section: Geometry Methods In Fixture Analysis and Verificationmentioning

confidence: 99%

Fixture Feasibility: Methods and Techniques for Fixture Planning

Kang

Peng

2008

Computer-Aided Design and Applications

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“…In this article, the workpiece locating errors and the machining errors were used as evaluation indexes for fixture design. With consideration of 3-2-1, Pin-Hole and V block, Rong et al 5 proposed a locating error analysis method for three fixture layouts. In Raghu and Melkote, 6 Qin et al, 7 Vishnupriyan et al, 8 Zhu et al 9 and Wang, 10 factors including geometric errors of workpiece and fixture are considered.…”

Section: Introductionmentioning

confidence: 99%

Locating error analysis for workpieces with general fixture layouts and parameterized tolerances

Tang

et al. 2014

Proceedings of the Institution of Mechanical Engineers, Part B:

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In manufacturing engineering, locating error analysis for workpieces is a common issue in predicting the quality of machined features, computer-aided fixture design and tolerance allocation. This article presents a locating error analysis approach for workpiece with general fixture layouts and parameterized tolerances. Initially, a fixture is transformed into six locating points in the space. A linearized model is then derived to convey the relationship between the errors of locating points and the locating errors, by using the implicit differentiation and the first-order Taylor expansion. Then, the tolerances for the features of plane, cylinder and free-form surface are parameterized using 4 × 4 homogeneous transformation matrices. Finally, two formulas are derived to calculate the errors in the locating points in surface-to-surface mating and hole-to-pin mating. Two workpieces are presented to demonstrate and validate the proposed method. The relative errors between the results calculated by the proposed method and the results calculated by 3DCS are less than 3%.

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“…This can have a profound influence on the position and orientation of the part in the fixture. With a tolerance sensitivity analysis, one can determine this influence of the misplacement of the locators and calculate the allowable tolerances in the locator placement [29][30][31]. Automatically reconfigurable fixtures holding integrated position transducers should offer sufficient position resolution.…”

Section: Verification Analysesmentioning

confidence: 99%

Recent Research on Flexible Fixtures for Manufacturing Processes

Bakker¹,

Papastathis²,

Ratchev³

et al. 2013

MENG

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Fixtures, are used to fixate, position and support workpieces, and form a crucial tool in manufacturing. Their performance influences the manufacturing (and assembly) process of a product. Furthermore, fixturing can form a significant portion of the needed investment and total process planning time for the manufacturing system. Many fixturing concepts, as contribution to increase the flexibility of the manufacturing system, are reported in the literature. The flexible fixturing designs can be classified into the following seven categories: modular fixtures, flexible pallet systems, sensor-based fixture design, phase-change based concepts, chuck-based concepts, pin-type array fixtures and automatically reconfigurable fixtures. It is observed that the more intelligent and automated fixturing systems are designed with the demands for automation in certain industries in mind. Furthermore, different fixturing solutions suit the engineering demands for different manufacturing areas, this means that for the foreseeable future all technologies will remain current. From the self-reconfigurable fixturing techniques a new fixturing capability is emerging: in process reconfigurability for the optimal placement of clamps and supports during the whole process time. These several concepts together with some recent patents are studied here. The paper concludes with some prospective research directions in the field of flexible fixturing.

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Locating error analysis and tolerance assignment for computer-aided fixture design

Cited by 53 publications

References 5 publications

Fixture Feasibility: Methods and Techniques for Fixture Planning

Fixture Feasibility: Methods and Techniques for Fixture Planning

Locating error analysis for workpieces with general fixture layouts and parameterized tolerances

Recent Research on Flexible Fixtures for Manufacturing Processes

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