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针对0Cr18Ni9不锈钢连续多弯导管在实际生产中成形质量差、尺寸精度低的问题,采用数控弯曲成形数值仿真的方法优化工艺参数,提高产品的成形质量。基于有限元仿真平台,建立管材数控弯曲成形、抽芯及回弹的三维有限元模型,并通过仿真与试验结果的对比验证模型的准确性。由于连续多弯导管由多个弯曲段组成,首先研究各个弯头成形过程中的关键工艺参数对成形结果的影响,对工艺参数组合进行优化,基于此进行连续多弯导管成形仿真。结果表明:简单采用各个单弯管件的最优工艺参数的组合进行连续多弯导管的成形并不能得到合格的管件,通过调整前后两次弯制的弯曲角度组合,补偿两个弯头之间的应力干涉对成形精度的影响,获得了成形质量满足要求的合格产品。 相似文献
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冷弯成形工件具有高效、经济的特点,发达国家每年冷弯成形工件的用量占钢铁用量的8%,而叠合型材是冷弯件中应用最多的一类,但由于存在回弹引起的质量问题,设计人员通常会以降低工件的其他性能以达到相似产品形状。该文基于型材叠合的虚拟弯曲理论,利用PROFIL冷弯轧辊计算机辅助设计软件及该软件自动建立ABAQUS模型的功能,分析冷弯成形过程。为验证虚拟弯曲理论的设计效果,分别建立了常见原始工艺路线和基于虚拟弯曲理论的叠合成形工艺路线,并利用有限元模拟,分析了两种板材叠合成形的工艺路线。受力分析结果和模拟结果均表明,叠合型材的补助弯曲设计可以解决叠合型材的回弹问题。 相似文献
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基于凸弯边橡皮成形模拟分析和试验验证,分析了橡皮的不同简化模型对凸弯边橡皮成形起皱模拟精度的影响。在用ABAQUS模拟凸弯边橡皮成形时,橡皮简化为厚向4 mm的体单元网格,并用增强的沙漏控制模型,可兼顾计算精度和计算效率。基于工艺参数对凸弯边橡皮成形起皱规律的影响规律,确定了影响凸弯边橡皮成形的橡皮硬度和压力的最佳工艺参数。基于有限元模拟和试验设计,获取不同几何结构的凸弯边橡皮成形极限弯边高度。通过数学分析方法,建立了TB5钛合金凸弯边橡皮成形极限预测模型,并用试验验证其预测的准确性。 相似文献
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对TA2纯钛板辊弯成形回弹显微机理进行了系统研究,采用辊弯成形工艺对TA2纯钛板进行了单道次及多道次不同设计角度的冷变形加工。首先,研究了不同设计角度辊弯成形板材的回弹规律,其次,利用显微硬度计测试了辊弯成形样品的显微硬度变化,最后,通过电子背散射衍射实验研究了TA2辊弯成形板材的显微组织、织构和取向差的演变规律。结果表明,在单道次辊弯成形实验中,随着设计角度的增大,回弹逐渐减小,显微硬度逐渐增大,主要原因是孪生参与协调塑性变形,织构强度逐渐增大,变形量增大导致位错密度降低。在终设计角度为30°的辊弯成形实验中,随着道次数的增加,回弹逐渐增大,而显微硬度逐渐降低,孪生现象消失,织构强度逐渐降低,位错密度逐渐增大,这是由变形量递增,反复加载卸载后通过位错滑移产生的弹性回复逐渐增大导致的,这是由辊弯成形所特有的工艺特点决定的。 相似文献
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针对方矩形焊管在冷弯成形过程中的回弹问题,利用COPRA软件进行冷弯成形工艺设计,确定了适用于柔性制造的工艺参数,基于ABAQUS软件建立了8种冷弯成形有限元模型,先后进行显示动力学分析和静力学分析,模拟板材冷弯成形和卸载过程,得到了不同模型各道次的回弹角度,同时,通过单因素分析法研究了板料厚度、侧壁高度和成形宽度对回弹的影响。结果表明:最终成形角相同时,回弹角度呈先增大后减小的趋势;增大板料厚度、成形宽度和减小侧壁高度均会分别导致冷弯成形中各道次的回弹角度减小,且回弹角度与板料厚度成线性关系;在进行弯角二的冷弯成形过程中,宽度方向板材的等效应力基本不变,弯角一不会发生回弹现象。 相似文献
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制造信息的收集整理与集成是面向工艺方案设计的重要技术单元.本文从制造信息学的角度出发,构造一种基于制造信息驱动的面向工艺方案设计的集成信息系统.该系统关注的主要问题集中在有关制造水平环节的工艺设计领域内.通过对零件几何信息与非几何信息进行集成或解析,以便构造和获取适宜的制造信息模型.构造该信息系统的关键技术在于工艺设计过程中所涉及的制造信息模型及相关数据结构的建立,并通过认知主体的干涉与控制,以实现自信源至信宿的信息内容传递与处理.系统获取的大量制造信息数据最终存储于面向对象的工程数据库.在基于模糊综合评估理论的推理机制作用下,通过组织和调用这些数据,以获得最优的工艺方案设计. 相似文献
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针对传统装配序列规划不考虑非单调因素的问题,提出一种基于知识规则与几何推理的非单调装配序列规划方法。首先,对非单调装配过程及其特点进行了分析,并采用包含状态信息的层次关联图及装配知识规则两种方式对非单调装配过程信息进行表达。最后依据所建立的装配信息模型,采用基于知识规则与几何推理相结合的非单调装配序列生成方法,实现非单调装配序列的规划。 相似文献
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H. H. Jo S. K. Lee S. B. Lee B. M. Kim 《International Journal of Machine Tools and Manufacture》2002,42(6):763
This paper describes a numerical analysis of non-steady state porthole die extrusion, which is useful for manufacturing long tubes with a hollow section. Materials divided through several portholes are gathered within a chamber and are then welded under high pressure. This weldability classifies the quality of tube products and is affected by process variables and die shapes. However, porthole die extrusion has been executed based on the experience of experts, due to the complicated die assembly and the complexity of metal flow. To better assist the design of die and to obtain improvement of productivity, non-steady 3D FE simulation for porthole die extrusion is required. Therefore, the objective of this study is to analyze the behavior of metal flow and to determine the welding pressure of hot extrusion products according to various billet temperatures, bearing length, and tube thickness by FE analysis. The results of FE analysis are compared with those of experiments. 相似文献
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为了使CAM系统能直接准确读取CAD系统中与CAM相关的产品加工信息,应用ICES(Initial Graphics Exchanges Specification)规范,提出一种基于工厂设计模式的加工信息提取框架。它并未采用硬编码方式,而是将几何实体的创建过程从客户端程序中分离出来,这就大大提高了该接口可组合性、可维护性以及可复用性,为解决集成制造系统的信息共享问题提供了一种实用方法。 相似文献
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以建立满足工序需求的工件定位点数量最少的定位布局为目标,以定位法线为介质,基于定位法线的工件定位的几何定理,推论出工件自由度与定位法线关系,获得自由度约束模型的定位法线信息;建立工件自由度数学模型,运用逻辑减运算法则建立工件各类型自由度之间关系,获得自由度模型的规划方案;根据规划方案中的定位法线信息,得出定位点初始布局。利用典型实例详细介绍了基于定位法线进行工件定位点布局规划的应用过程。该方法仅需自由度信息,规划过程简便,适用于各类工件,尤其是复杂工件的初步定位方案设计。 相似文献
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Qing Liu Chun Zhang H.-P. Ben Wang 《International Journal of Machine Tools and Manufacture》1997,37(3):237-248
The manufacturing of high-quality products at low costs is one of the greatest challenges of every company today. Form accuracy is among the quality parameters of machined parts and is directly related to functional performance. Control and improvement of form accuracy is to be performed under the computer-integrated manufacturing (CIM) concept. This paper investigates the form accuracy of mechanical machining and studies the essential aspects and procedures of form-accuracy simulation. The emphases are on the integration of form-accuracy analysis and the simulation into the CIM database construction and virtual manufacturing. Form-accuracy analysis in this paper reveals that the inherent drawbacks in design will directly affect the geometric quality of a workpiece, and proper process planning can enhance the manufacturability of parts with the required geometric quality. The simulation procedure implemented in this paper can be used at the design stage to predict the form accuracy of a machined part and functional performance. The procedure can also be used at the process planning stage to predict and control form accuracy during the machining process. 相似文献
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An expert system for generation of machine inputs for laser-based multi-directional metal deposition 总被引:1,自引:1,他引:0
Rajeev Dwivedi Radovan Kovacevic 《International Journal of Machine Tools and Manufacture》2006,46(14):1811-1822
Laser-based multi-directional metal deposition (LBMDMD) is a very effective way of fabricating a part directly from its digital model. The method, however, requires a lot of human intervention during the process planning. Driven by already developed expert systems for the process planning in Computer Aided Design (CAD) and manufacturing, this paper intends to suggest a task framework for the automation of the process planning for LBMDMD using principles of Artificial Intelligence (AI). The process can be divided into distinct steps, and geometric reasoning can be applied to determine a set of facts and rules for the automation. The principles of first order logic are applied for the representation and further simplification of the process into a set of “if–then” based rules. This paper explains the framework, the facts, and the rule base used for the process planning. 相似文献
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N. Ismail N. Abu Bakar A.H. Juri 《International Journal of Machine Tools and Manufacture》2005,45(6):649-655
The work presented in this paper proposes a new technique called Edge Boundary Classification (EBC) for feature recognition from B-rep models. The technique uses the spatial addressability information of solid models that identifies the solid and void ‘sides’ of a boundary entity. Features can be interpreted from B-rep models based on the spatial properties of boundary entities. The purpose of feature recognition is to convert the geometric CAD data of a modeled part into a set of features suitable to support manufacturing activities such as in process planning system and inspection system. The application of the technique for cylindrical-based and conical-based features is presented. A case study is discussed and demonstrated to validate the proposed algorithms. 相似文献