共查询到18条相似文献,搜索用时 375 毫秒
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夹具布局和夹紧力大小影响切削变形的大小和分布.基于遗传算法和有限元方法,提出一种夹具布局和夹紧力优化设计方法.该方法将同步优化夹具布局和夹紧力大小以及施加变夹紧力相结合,首先以加工变形最小化和变形分布最均匀为目标同步优化夹具布局和夹紧力大小,然后在优化后的夹具布局的基础上求解使得加工变形最小的变夹紧力大小.使用该方法进行底座薄壁零件的夹具优化设计,结果表明优化得到的设计优于经验设计和多目标优化方法,该方法有效地降低了加工过程中工件的变形,提高变形均匀度. 相似文献
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首先通过分析缸盖与夹具定位元件、夹紧元件之间的接触特点,建立了相应的接触副模型。在假定夹具夹紧点的布局位置以及夹紧顺序固定的基础上,以定位元件与工件接触区域半弹性变形所导致的工件最小位移为第一目标函数,同时以接触点变形最小总余能为第二目标函数。根据工件的具体加工过程静力平衡列出约束条件,构建了夹紧力的多目标优化模型。最后,根据多目标优化模型得到相应的结果。夹具的多重夹紧力经过该模型优化后,对应所需的夹紧力显著降低,这对提高加工精度和减少成本具有重要的意义。 相似文献
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杨亚辉 《机械设计与制造工程》2016,(10):25-28
利用改进的遗传算法对机床夹具夹紧力进行了优化分析,首先对遗传算法进行了优化,然后建立了夹紧力的优化目标及相应的约束条件,最后采用混合遗传算法对该优化模型进行优化。结果表明,优化后的夹紧力明显减小,而且各个方向的夹紧力分布也更为合理。该方法对其他夹紧力的计算具有一定的参考意义。 相似文献
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机床夹具在设计过程中夹紧力的计算 总被引:2,自引:0,他引:2
在机床夹具的设计过程中,夹紧力起着非常重要的作用。本文结合应用实例,主要介绍了在实际加工中如何正确计算夹紧力的大小,基本思路是根据静力平衡原理求出理论夹紧力的大小,然后乘以安全因数得到合理的实际夹紧力的大小。 相似文献
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Machining fixture layout design using ant colony algorithm based continuous optimization method 总被引:3,自引:2,他引:1
K. P. Padmanaban K. P. Arulshri G. Prabhakaran 《The International Journal of Advanced Manufacturing Technology》2009,45(9-10):922-934
In any machining fixture, the workpiece elastic deformation caused during machining influences the dimensional and form errors of the workpiece. Placing each locator and clamp in an optimal place can minimize the elastic deformation of the workpiece, which in turn minimizes the dimensional and form errors of the workpiece. Design of fixture configuration (layout) is a procedure to establish the workpiece–fixture contact through optimal positioning of clamping and locating elements. In this paper, an ant colony algorithm (ACA) based discrete and continuous optimization methods are applied for optimizing the machining fixture layout so that the workpiece elastic deformation is minimized. The finite element method (FEM) is used for determining the dynamic response of the workpiece caused due to machining and clamping forces. The dynamic response of the workpiece is simulated for all ACA runs. This paper proves that the ACA-based continuous fixture layout optimization method exhibits the better results than that of ACA-based discrete fixture layout optimization method. 相似文献
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S. Selvakumar K. P. Arulshri K. P. Padmanaban K. S. K. Sasikumar 《The International Journal of Advanced Manufacturing Technology》2013,65(9-12):1573-1586
In machining fixtures, minimizing workpiece deformation due to clamping and cutting forces is essential to maintain the machining accuracy. This can be achieved by selecting the optimal location of fixturing elements such as locators and clamps. Many researches in the past decades described more efficient algorithms for fixture layout optimization. In this paper, artificial neural networks (ANN)-based algorithm with design of experiments (DOE) is proposed to design an optimum fixture layout in order to reduce the maximum elastic deformation of the workpiece caused by the clamping and machining forces acting on the workpiece while machining. Finite element method (FEM) is used to find out the maximum deformation of the workpiece for various fixture layouts. ANN is used as an optimization tool to find the optimal location of the locators and clamps. To train the ANN, sufficient sets of input and output are fed to the ANN system. The input includes the position of the locators and clamps. The output includes the maximum deformation of the workpiece for the corresponding fixture layout under the machining condition. In the testing phase, the ANN results are compared with the FEM results. After the testing process, the trained ANN is used to predict the maximum deformation for the possible fixture layouts. DOE is introduced as another optimization tool to find the solution region for all design variables to minimum deformation of the work piece. The maximum deformations of all possible fixture layouts within the solution region are predicted by ANN. Finally, the layout which shows the minimum deformation is selected as optimal fixture layout. 相似文献
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B. Li S. N. Melkote 《The International Journal of Advanced Manufacturing Technology》2001,18(10):701-707
This paper presents a fixture layout and clamping force optimal synthesis approach that accounts for workpiece dynamics during
machining. The dynamic model is based on the Newton– Euler equations of motion, with each fixture–workpiece contact modelled
as an elastic half-space subjected to distributed nor-mal and tangential loads. The fixture design objective in this paper
is to minimise the maximum positional error at the machining point during machining. An iterative fixture layout and clamping
force optimisation algorithm that yields the "best" improvement in the objective function value is presented. Simulation results
show that the proposed optimis-ation approach produces significant improvement in the work-piece location accuracy. Additionally,
the method is found to be insensitive to the initial fixture layout and clamping forces. 相似文献
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Development of a finite element analysis tool for fixture design integrity verification and optimisation 总被引:2,自引:1,他引:2
Nicholas Amaral Joseph J. Rencis Yiming Rong 《The International Journal of Advanced Manufacturing Technology》2005,25(5-6):409-419
Machining fixtures are used to locate and constrain a workpiece during a machining operation. To ensure that the workpiece is manufactured according to specified dimensions and tolerances, it must be appropriately located and clamped. Minimising workpiece and fixture tooling deflections due to clamping and cutting forces in machining is critical to machining accuracy. An ideal fixture design maximises locating accuracy and workpiece stability, while minimising displacements.The purpose of this research is to develop a method for modelling workpiece boundary conditions and applied loads during a machining process, analyse modular fixture tool contact area deformation and optimise support locations, using finite element analysis (FEA). The workpiece boundary conditions are defined by locators and clamps. The locators are placed in a 3-2-1 fixture configuration, constraining all degrees of freedom of the workpiece and are modelled using linear spring-gap elements. The clamps are modelled as point loads. The workpiece is loaded to model cutting forces during drilling and milling machining operations. Fixture design integrity is verified. ANSYS parametric design language code is used to develop an algorithm to automatically optimise fixture support and clamp locations, and clamping forces, to minimise workpiece deformation, subsequently increasing machining accuracy. By implementing FEA in a computer-aided-fixture-design environment, unnecessary and uneconomical “trial and error” experimentation on the shop floor is eliminated. 相似文献
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B. Li S.N. Melkote 《The International Journal of Advanced Manufacturing Technology》2001,17(2):104-113
Workpiece motion arising from localised elastic deformation at fixture-workpiece contacts owing to clamping and machining
forces is known to affect significantly the workpiece location accuracy and, hence, the final part quality. This effect can
be minimised through fixture design optimisation. The clamping force is a critical design variable that can be optimised to
reduce the workpiece motion. This paper presents a new method for determining the optimun clamping forces for a multiple clamp
fixture subjected to quasu-static machining forces. The method uses elastic contact mechanics models to represent the fixture-workpiece
contact and involves the formulation and solution of a multi-objective constrained oprimisation model. The impact of clamping
force optimisation on workpiece location accuracy is analysed through examples involving a 3-2-1 type milling fixture. 相似文献
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Manjuri Hazarika Uday S. Dixit Sankha Deb 《The International Journal of Advanced Manufacturing Technology》2010,51(9-12):1099-1109
Setup planning is an important part of process planning that has been widely investigated by various researchers. However, the output of the traditional setup planning approaches is limited and insufficient for the upstream process planning activity, fixture design. In this work, a setup planning system is developed that provides sufficient inputs to the fixture designer in terms of recommended depth of cut and feed, fuzzy clamping forces, near optimal locator and clamp layout, and sizes of the locators and clamps. The fixture designer can further optimize the fixture plan by taking these inputs. The methodology is illustrated with the help of an example. 相似文献
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优化定位布局是减小薄壁件装夹变形的重要手段,现有研究大多以节点法向变形最小为优化目标而忽略其他方向上的变形,为此提出了一种新的基于花授粉算法的夹具布局优化方法。针对曲面薄壁件,在建立法向约束定位模型的基础上,通过应变能来描述所有方向上的变形,以薄壁件的整体应变能最小为目标,结合花授粉算法和基于Python语言的参数化有限元分析,实现薄壁件的定位布局寻优。最后以飞机蒙皮定位布局优化为例验证方法的有效性,并通过与遗传算法的对比表明,花授粉算法在优化薄壁件的定位布局时具有更优的性能。 相似文献
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Shaopeng Tian Zhengdong Huang Liping Chen Qifu Wang 《The International Journal of Advanced Manufacturing Technology》2006,30(1-2):76-86
In this paper, we present an approach for optimally selecting the locating positions of workpieces and identifying feasible clamping regions that meet the requirements of the form-closure principle for fixture layout. This approach firstly finds an optimal configuration of locating points on a set of faces of the workpiece which minimizes the error transfer from locating points to machining features. In the formulation of the optimization, the error transfer is modeled using an error transfer matrix. The eigenvalues of the matrix are used as objective functions of the optimization. Secondly, this approach computes the clamping wrench cone and its member wrench can form a form-closure fixture layout, together with the formerly selected locating points. Finally, it generates the feasible clamping regions by projecting the clamping wrench cone onto faces of the clamping feature faces. An example is included to illustrate the effectiveness of the proposed approach. Compared with traditional methods in which only error transfer from the locating points to the workpiece’s mass-center is considered, the error transfer control in this approach is more effective and of greater efficiency. In addition, the clamping wrench cone projection method for the generation of feasible clamping regions is more suitable for handling cases with concave clamping faces than traditional convex-combination-based methods. 相似文献