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High-speed ACFM tests were carried out using a rotary test piece that contained spark-eroded notches. The ACFM sensor detected the induced notches during inspection at 121.5 km/h. The recorded signal remained unaffected by the increases in inspection speed under constant lift-off. To simulate actual rail inspection conditions at high speed, further tests were carried out using a spinning rail rig and a set of rails that contained spark-eroded notches of various shapes and sizes up to a speed of 32 km/h. Although, the ACFM sensor successfully detected the majority of the notches, the signal obtained was affected by lift-off variations. 相似文献
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气辅注射成型参数设置不合理会造成吹穿、气指、缩水、穿透不足等各种成型缺陷.利用Moldflow软件采用正交实验法对提手GAIM的主要工艺参数:熔体温度、注射时间,熔体体积、气体延迟时间、气体注射时间,及压力进行模拟分析,在对每次实验结果进行分析基础上,对成型参数进行进一步优化.采用优化工艺,气体贯通整个提手,产品质量减... 相似文献
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对家电产品中常用的碳素结构钢Q215A"U形件"弯曲回弹进行有限元数值模拟,分析出凹模圆角半径,凸、凹模间隙,摩擦因数和凸模速度等与弯曲回弹量的关系,为模具制造和冲压生产从业人员提供有益的参考。 相似文献
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Effect of residual stress on ACFM crack measurements in drill collar threaded connections 总被引:5,自引:0,他引:5
The drill collar threaded connection of the type used in hydrocarbon exploration is a critical component of the drillstring that is highly susceptible to fatigue damage. In an attempt to reduce costly downhole failures the connections are cold rolled to introduce compressive residual stress, and when in service the connections are routinely inspected. The Alternating Current Field Measurement (ACFM) technique is an increasingly popular method of thread inspection, however, results have indicated that the ACFM defect sizing capability may be compromised when it is used to inspect recently cold rolled connections. If a connection is cold rolled without first being defect free, subsequent inspections may under estimate crack depth with the standard interpretation. Inspection before rolling is therefore necessary. 相似文献
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针对高强钢纵弧棱U型梁类件的冲压成形问题,分析了纵弧棱U型梁成形件各个区域的冲压变形特点,再通过有限元分析总结了其成形过程的应力、应变分布情况和厚度变化规律,并结合模拟结果与物理试验探讨了该类零件在成形过程的减薄和增厚行为.验证结果表明:该梁类件的主要变形区为翼板区,且厚度从端部至中部逐渐减小;主要危险部位处于中部侧壁... 相似文献
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在介绍一种斜对称U形弯曲件结构特点的基础上,对零件加工工艺性进行了分析,并且对弯曲模加工的零件产生变形原因进行了探讨,借助有限元软件对零件弯曲变形过程进行了数值仿真,使变形现象更为直观。针对零件产生缺陷的原因,对弯曲模结构进行了改进,使制件完全达到设计要求。 相似文献
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为了掌握U形件回弹的规律,本文运用数值模拟技术及回归分析的方法,建立了U形件校正弯曲的多因素回弹预测数学模型.此模型与实验结果的相关性达到了86%,并对结果进行了残差分析验证,对U形件回弹起到了较好的预测作用. 相似文献
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构建了自阻加热在线冲压试验平台,设计并制造了U形弯曲成形模具,对自阻加热冲压技术进行了工艺验证试验。结果表明:仅需对模具、夹具进行适当创新设计,自阻加热冲压就可以在传统设备上进行,从而显著降低热冲压件的生产成本。为了制造汽车车身上的高强度钢U形梁类零件,设计了一套自阻加热冲压工艺装备:专用弹性夹持装置可以快速夹紧、卸下金属板坯,同时提供弹性拉力,消除细长板坯由于热胀冷缩或自重引起的弯曲,并减小冲压过程对通电回路的冲击;切断弯曲模具两端的冲裁结构与压边顶件的机构配合,可以实现工件的自动顶出,从而提高生产效率。 相似文献
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对U形固定夹进行了工艺分析,详细介绍了各成形工序的模具结构特点、在试模过程中出现的问题、解决这些问题的方法和补救措施,充分考虑了模具结构的可调整性、易损件的更换和模具制造成本的控制。模具已投入生产达3年,经济效益好。 相似文献
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Investigation on the bar clamping position of a new type of precision cropping system with variable frequency vibration 总被引:3,自引:0,他引:3
L.J. Zhang S.D. Zhao J. Lei W. Liu 《International Journal of Machine Tools and Manufacture》2007,47(7-8):1125-1131
The purpose of this paper is to obtain the correct clamping position of the bar during the cropping process based on a new type of precision cropping system with variable-frequency vibration. The mathematical model is built by finite-element method and the simulation experiments were designed by means of an orthogonal method. The analytical results show that the diameter D of the bar exerts an influence on the ratio of the maximum tension stress to the maximum shear stress near the notch bottom remarkably. The influence of the length L2 of second-segment bar extending out the clamping die on it can be minimal. The reasonable geometrical parameters of the clamping bar for a segment of bar with definite length to diameter ratio are determined: the proportion of L1 to the diameter D of the bar is 0.3, and the proportion of L2 to D is 0.25. According to the special feature of the obtained cutting surface, a new measurement method is proposed and applied to assess the quality of the cross-section. The theoretical analysis and experiments prove that, by reasonably setting clamping position of the bar, high-quality cross-section can be obtained. 相似文献
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