Concurrent tolerance allocation and scheduling for complex assemblies

Geetha, K.; Ravindran, D.; Kumar, M. Siva; Islam, M. N.

doi:10.1016/j.rcim.2015.03.001

Cited by 28 publications

(13 citation statements)

References 55 publications

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“…However, the relationship between the tolerance band and production cost of the driving actuator is so complex that there is almost no ready-made cost-tolerance model. Therefore, the principles generally applied in the real-life engineering for tolerance design, namely, the equal and scaled tolerances, 40,41 will be adopted to conduct the input tolerance design for parallel mechanisms. To be specific, the equal tolerance means to select the actuators with the same allowable deviation intervals, whereas the scaled tolerance indicates these intervals are proportional with the prescribed coefficient.…”

Section: Tolerance Designmentioning

confidence: 99%

A novel approach of input tolerance design for parallel mechanisms using the level set method

Zhao

Guo

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part B:

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Input uncertainties inevitably result in the output error for parallel mechanisms, which will lead to significant influence on good work performance. To control the output error within the specification boundary, this article proposes a novel approach of input tolerance design based on the level set method for the driving joint. The implementation of the proposed method can be divided into two subtasks. First, using the level set method, the exact input error boundary is determined by means of evolving an initial input error interface with a defined normal speed field, thereby transforming the problem of exploring the exact boundary into solving a partial differential equation with initial value. On this basis, according to the equal and scaled principles, the tolerance width of each input is evaluated in an intuitionally geometrical manner, that is, searching the maximum geometry corresponding to the principle inside the exact input error boundary. Finally, two planar parallel mechanisms with different degrees of freedom are introduced as numerical examples to demonstrate the execution and effectiveness of the proposed method.

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Section: Tolerance Designmentioning

confidence: 99%

A novel approach of input tolerance design for parallel mechanisms using the level set method

Zhao

Guo

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part B:

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“…The other property of the dimensional analysis is the form-closure for rigid motions derived from the kinematic formulations, the simplest form of which is the error accumulation and allocation according to the AS of the parts. The second base drives many research fruits from the tolerance synthesis for rigid assemblies 31,32 to the variation analysis for multistage assemblies. 33,34 Meanwhile, the combination of the FEA with kinematic formulations also supports the dimensional tolerance, error, and variation analyses for compliant assemblies.…”

Section: Assembly Dimensional Analysismentioning

confidence: 99%

Assembly sequence optimization for minimizing the riveting path and overall dimensional error

Tang

Mao

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part B:

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Due to the complexities of calculations based on different representations of constituent parts in an assembly, the combined improvement of efficiency and precision for the riveting has seldom been studied by the sequence planning or dimensional engineering. This article develops an assembly sequence optimization method that simultaneously minimizes the path length and overall dimensional error for the solid riveting. The sequence is denoted by the order of classifications for the nodes around the rivet holes in the finite element model for the assembly. Ant colony algorithm is applied on the optimization by integrating two calculations, that is, the length calculation of riveting path and the calculation of the dimensional error related to rivet upsetting directions and assembly sequence. Results for three assemblies are presented which show a good degree of optimization in performance for different scales of assemblies with different numbers of rivets that share the same solid riveting process.

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“…The general practice of mechanical tolerance design is to treat tolerance design as a combination of tolerance modeling, assembly simulating, tolerance allocation, and optimization. The best combination of part tolerance is assigned through multi-dimensional objective constraints in order to meet environmental clearance, conform to functional requirements, improve product quality, and lower manufacturing costs in the late design stage [4][5][6]. To increase the accuracy and robustness of the designed tolerance scheme, the influence of processing feature degradation caused by machining precision deterioration is taken into consideration.…”

Section: Introductionmentioning

confidence: 99%

Assembly Tolerance Design Based on Skin Model Shapes Considering Processing Feature Degradation

Zhang

Qiu

et al. 2019

Applied Sciences

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To increase the reliability and accuracy of tolerance design, more and more research works are considering not only orientation and position deviations; they are also forming errors in tolerance modeling. As a direct cause of form errors in industrial mass production, the processing features of the machining system degrade over time. Under the Industry 4.0 paradigm, an assembly tolerance design method based on Skin Model Shape is proposed to take the effect of degrading processing features into consideration. A continuous-time multi-dimensional Markov process is trained through maximum likelihood estimation based on the nodal sampling point set on the machined surface. Degradation of the machined surface is modeled based on the joint probability distribution of nodal displacements. Assembly force constraints and assembly entity constraints are applied to spatial assembly simulations. Tolerance synthesis takes the manufacturing cost and assembling probability as design objectives. A design example of the rotary feed component in a five-axis machine tool is proposed for explanation and verification.

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Concurrent tolerance allocation and scheduling for complex assemblies

Cited by 28 publications

References 55 publications

A novel approach of input tolerance design for parallel mechanisms using the level set method

A novel approach of input tolerance design for parallel mechanisms using the level set method

Assembly sequence optimization for minimizing the riveting path and overall dimensional error

Assembly Tolerance Design Based on Skin Model Shapes Considering Processing Feature Degradation

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