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为提高当前柔性薄板零件装配偏差分析的效率,提出了一种考虑夹具配置的装配偏差分析模型。通过对柔性薄板的定位装配过程的研究,分析了零件偏差、夹具偏差和装配偏差在各个步骤中的变化过程,建立了N-2-1和3-2-1两种夹具定位规则下的装配前后偏差之间的线性关系;根据装配后夹具定位点的释放模式的不同,建立了过定位释放和完全释放两种模式下的装配偏差分析模型。最后,通过分析实例薄板的装配偏差,表明了该装配偏差分析模型的有效性。 相似文献
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对于在加工、装配、使用和维修过程中,多次装拆而能准确保持相对位置的零件,通常采用定位销来确定零件的相互位置。一般情况下,采用销定位的两被连接件均不需淬火处理,此时只需将两零件预装在一起直接配作销孔即可。但有时两被连接件中其一不需淬火处理而另一件是淬火件时也要采用销定位。我们知道,淬火后零件不能配钻、铰,但销孔又必须配作,如果在淬火处理前加工好销孔,经过淬火处理后会产生变形,致使两零件上的销孔距不相等,从而无法安装。此时,可采用如图1所示方法解决。先在淬火件上作一个大于销钉直径的孔,淬火后,打磨该… 相似文献
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柔性件装配偏差的有限元分析 总被引:1,自引:0,他引:1
利用有限元法对两个刚性小、形状不同且易变形的柔性件进行装配偏差分析。采用"6-2-1"定位方式对柔性件进行定位,通过影响系数法对柔性件装配偏差进行建模,分析在焊接装配中产生的偏差。结合有限元软件Workbench和MATLAB进行仿真计算,与CATIA TAA分析结果进行对比。研究结果表明:薄板A中测量点偏差的分析结果与CATIA TAA仿真结果存在偏差,而薄板B中测量值与CATIA TAA仿真结果基本相同,验证了分析结果的有效性,为产品分析提供了方便。最后,研究了焊接点个数对柔性件装配偏差的影响,得出柔性件装配偏差随着焊接点个数的增加呈先减小、后增加的趋势。 相似文献
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传统柔性件装配偏差分析所使用的超元刚度矩阵以文件形式存在,导致装配偏差计算流程操作复杂,分析人工成本大大增加。使用有限元法封装装配偏差计算,根据边界条件直接输出装配偏差,从而简化装配偏差计算流程。开展薄板装配试验,通过与仿真装配偏差数据进行对比,验证了该装配偏差计算方法的正确性。 相似文献
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为了提高薄板件钻孔夹具定位布局仿真模型的薄板件变形预测精度,提出一种基于分形接触理论的薄板件钻孔夹具定位布局建模方法。首先采用半弹性接触模型近似代替定位元件与薄板件之间的接触,并通过法向弹簧—阻尼单元模拟接触面的刚度和阻尼特性,然后借助分形接触理论获得定位点接触区域法向接触力与接触刚度、阻尼的关系,接着在通过有限元仿真得到各定位点处的法向接触力的基础上,求解每个定位点处的法向接触刚度与阻尼,最后建立薄板件钻孔夹具定位布局仿真模型,对薄板件钻孔后的变形进行预测。通过平板和曲板两个实例验证了所提建模方法的可行性和有效性。 相似文献
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探讨了减小薄板件切削加工变形的工艺方法,通过分析变形产生的原因,结合生产经验,提出了合理可行的工艺措施,能够控制零件的变形,保证其平面度和尺寸精度. 相似文献
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为实现钣金件的数字化制造,提出了钣金的数控冲压加工,研究了基于CNCKAD软件的数控程序编制问题。首先,选择典型的数控冲压设备,编制冲压加工工艺;然后,建立制造数学模型,定义编程操作,生成数控机床用的加工程序;最后,通过实例仿真加工,验证了所述方法的可行性和正确性。 相似文献
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Fixture Configuration Design for Sheet Metal Assembly with Laser Welding: A Case Study 总被引:1,自引:1,他引:0
B. Li B.W. Shui K.J. Lau 《The International Journal of Advanced Manufacturing Technology》2002,19(7):501-509
The role of assembly fixtures is gaining importance in order to meet the special requirement of metal fit-up for sheet metal
assembly with laser welding. Fixture configuration methodologies based on a new proposed locating scheme have been developed.
In order to demonstrate the feasibility of the proposed fixture design principles in industrial applications, an industrial
case study with cross-members assembly is presented. In order to obtain a physical model with the actual tolerances, reverse
engineering technologies are employed for geometric modelling of the assembled parts. For achieving modelling accuracy a CMM-based
finite-element model is produced and performance characteristics of the 3D features obtained. In the case study, the assembly
weld patterns are designed first, to determine the weld locations. Then the general design, the deterministic optimisation
and the robust design of the fixture configuration are carried out sequentially. The results of the case study show that the
proposed fixturing principles are applicable and effective. 相似文献
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B. Li B.W. Shiu K.J. Lau 《The International Journal of Advanced Manufacturing Technology》2001,18(4):266-275
The quality of the stamping process has a direct effect on laser welded sheet metal assembly. The fixture plays an important
role in the satisfactory metal fit-up that laser welding requires. The traditional "3-2-1" locating scheme will no longer
suffice for the deformable laser sheet metal assembly process. Because of the often poor stamping quality, a complex die fixture
has to be employed to meet the metal fit-up requirements. The die fixture corresponds to an "infinite-2-1" locating scheme
where the tooling cost is very high and yet lacks flexibility. This limits the application of laser welding. In this paper,
a new locating scheme with both total locating and direct locating for welds is proposed. A total locating scheme is used
to locate the overall assembly, and a direct locating scheme is used to locate the weld location, which is critical for ensuring
correct metal fit-up. A finite-element model and a prediction and correction method for the direct locator configuration are
developed in this paper. A case study is used to show that the proposed method is effective for sheet metal assembly for laser
welding. 相似文献
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A fixture plays a key role in ensuring proper metal fit-up in sheet metal assembly with laser welding. In this paper, an optimal
fixture configuration design model is proposed based on a new locating scheme which includes both total locating and direct
locating on welds. In this model, both the number and the location of the concerned locators are taken as objectives. The
proposed prediction and correction method is used for determining the number of direct locators, and a pattern sorting method
is developed for determining the number of total locators. Considering the degree of metal fit-up (DMF) to be a fuzzy quantity,
a feasible evaluation criterion of DMF is also developed using a fuzzy synthesis evaluation method. A powerful optimisation
technique – genetic algorithm – is employed as the optimisation procedure. A case study is presented which demonstrates the
effectiveness of the optimal model, and the degree of metal fit-up can be improved compared to the initial locating scheme. 相似文献
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基于拉丁超立方抽样的薄板装配误差分析 总被引:1,自引:0,他引:1
提出了一种基于拉丁超立方抽样的薄板装配误差分析方法,该方法在装配过程模型中考虑了零件与零件、零件与焊枪间的接触作用。实例中,通过构造关键点误差与偏差源的响应面来实现拉丁超立方抽样与直接抽样的计算结果比较,结果证明,该方法的收敛效率大大提高。 相似文献
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板料成形中悬空区起皱过程的数值模拟 总被引:3,自引:0,他引:3
以逐级更新Lagrange描述的有限变形虚功原理为理论基础,采用Mindlin退化板壳单元,开发板料冲压成形起皱过程的有限元数值软件WRSIM,模拟了3种典型悬空区起皱问题,所得结果与实验观察基本一致,该软件可与其他成形过程数值模拟软件一起用于模具CAE,以使在模具设计冲压件件的可成形性。 相似文献