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电阻点焊质量决定了车身强度和车辆安全。超声无损检测方法常用于焊后抽检,但车身焊装完成后,结构内部诸多焊点难以触及,无法检测。针对上述问题,将超声检测技术应用于焊接过程监测,基于脉冲-回波超声探头与特征信号分析技术,研究点焊过程工件内部超声场瞬态分布情况;设计了新型内置超声波探头电极结构,将超声探头嵌入电极动臂水冷腔,进行脉冲电阻点焊超声在线监测试验,分析超声时程、焊接过程超声回波特征;利用声学信号实时记录焊核熔化和凝固过程,并研究点焊典型焊接缺陷虚焊的超声回波图特征,分析基于回波的虚焊焊点鉴别方法。研究结果表明,通过观察C扫描图像特征与A扫描信号的变化,能够很好地划分点焊接头的热影响区、熔合区、熔核区以及焊接缺陷。通过C扫描图像特征对虚焊焊点进行快速识别,进而实现点焊缺陷检测和熔核尺寸测量。 相似文献
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为解决使用现有超声检测系统评估电阻点焊熔核直径误差较大的问题,基于相控阵超声探头与特征信号分析技术,提出了一种点焊熔核直径定量化检测方法,重点研究了表面压痕对单阵元超声信号的影响规律,揭示了基于阵元超声信号的熔核边缘识别方法,并试验验证了熔核直径评估方法的精度.试验结果表明,点焊熔核直径的相控阵超声检测结果与金相检验结... 相似文献
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低碳钢点焊熔核直径的超声水浸聚焦法检测 总被引:1,自引:0,他引:1
介绍用超声水浸聚焦法测定低碳钢点焊熔核直径.检测及验证结果表明,根据透过焊点的超声波形第一峰值的变化情况,可以较准确地确定点焊熔核的直径. 相似文献
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采用不同焊接工艺对TRIP980钢板进行点焊试验,研究了焊接电流、焊前预热及焊后热处理工艺对点焊性能的影响. 结果表明,随着焊接电流的增大,焊点的熔核直径和拉剪力均增大,但当电流过大而发生飞溅时,焊点的熔核直径和拉剪力开始减小. 焊前预热工艺可提高点焊飞溅电流,进而可以获得更大的熔核直径及拉剪力. 在对焊点进行焊后热处理的情况下,当焊接电流与焊后热处理电流之间的冷却时间超过900 ms时,可显著改善熔核组织,降低熔核硬度,提高焊点拉剪力. 相似文献
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运用低碳钢薄板点焊超声检测有限元仿真模型,对气孔、压痕过深、熔核过小、脱焊等四种缺陷类型的点焊检测超声仿真信号进行快速傅里叶变换得到其频谱图,并采用统计学方法分别提取了超声信号时域和频域特征值.通过分析超声在不同缺陷焊点内部的传播规律,以及特征值的变化规律,总结了点焊缺陷类型的识别方法.利用该方法对大量点焊试样超声检测试验信号进行缺陷识别并与金相试验结果对比分析. 结果表明,综合分析超声检测信号时域和频域特征值规律,能够有效地识别点焊缺陷类型. 相似文献
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文中采用永磁体作为磁场源,研究了外加稳定磁场对铝合金电阻点焊的熔核尺寸、焊点力学性能、断裂模式以及微观组织的影响.文中还对熔核直径与峰值载荷之间的关系进行了研究.结果表明,永磁铁的工作距离对熔核直径大小具有重要影响.距离越近,外磁场促进熔核直径增加的效果越明显.外加磁场能够有效增加焊点熔核直径、提高点焊接头的剪切拉伸强度、促进断裂模式由界面断裂向纽扣断裂转变.在不同工艺参数下,熔核直径增长在3.5%~14.1%,剪切拉伸力可提高4%~25%.外加磁场可促进点焊熔核内等轴晶的形成和细化.峰值载荷与熔核尺寸、工件厚度、母材极限抗拉强度的乘积具有良好的线性关系. 相似文献
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采用AlSi5铝合金焊丝,冷金属过渡方法对汽车车身用6061铝合金进行了搭接点塞焊试验,研究了送丝速度、铝板孔直径、点塞焊时间对点塞焊接头焊点直径、焊核直径和拉伸载荷的影响.结果表明,送丝速度主要影响焊点直径的大小,点塞焊时间和铝板孔直径主要影响焊核直径和拉伸载荷.接头拉伸载荷主要取决于焊核直径的大小,焊核直径越大,拉伸载荷越大,与焊点直径关系不大.接头为典型的熔焊接头,焊缝主要由α-Al固溶体和Al-Si共晶相组成,点塞焊接头断裂方式为撕裂型断裂. 相似文献
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Electron beam welding (EBW) is a fusion welding process in which a beam of high-velocity electrons is applied to two materials to be joined.It is a complex high-temperature metallurgical process,and the quality of welding may deteriorate because of defects caused by improper welding parameters,especially in the EBW of thickened aluminum alloy plate.Ultrasonic phased array(UPA) technology has been applied more widely in the field of nondestructive testing because of its ability of effectively controlling the shape and direction of the emitted ultrasonic beam.In present research,a specimen with EBW seam on thickened aluminum plate was tested with a linear array ultrasonic phased array probe,and a large number of B-scan images of the weld were acquired by electronic scanning in probe combined with the mechanical scanning of the probe along the weld direction.This large number of B-scan images were stacked to construct the volume data,with which the 3D image of the weld discontinuities were reconstructed,and the 3D visualization was realized.More details about weld discontinuities' spatial distribution and orientation were revealed,and this approach also made the results of non-destructive ultrasonic testing more easily to understand. 相似文献
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《中国焊接》2016,(2)
Electron beam welding(EBW) is a fusion welding process in which a beam of high-velocity electrons is applied to two materials to be joined.It is a complex high-temperature metallurgical process,and the quality of welding may deteriorate because of defects caused by improper welding parameters,especially in the EBW of thickened aluminum alloy plate.Ultrasonic phased array(UPA) technology has been applied more widely in the field of nondestructive testing because of its ability of effectively controlling the shape and direction of the emitted ultrasonic beam.In present research,a specimen with EBW seam on thickened aluminum plate was tested with a linear array ultrasonic phased array probe,and a large number of B-scan images of the weld were acquired by electronic scanning in probe combined with the mechanical scanning of the probe along the weld direction.This large number of B-scan images were stacked to construct the volume data,with which the 3D image of the weld discontinuities were reconstructed,and the 3D visualization was realized.More details about weld discontinuities' spatial distribution and orientation were revealed,and this approach also made the results of non-destructive ultrasonic testing more easily to understand. 相似文献
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针对两层板及三层板组合下的5052铝合金进行了外加磁场与常规情况下的电阻点焊,研究了外加磁场对铝合金点焊熔核偏移影响. 结果表明,外加磁场改善了两层板及三层板非等厚度铝合金的熔核偏移情况,尤其是针对熔核偏移较严重的板材厚度组合下,外加磁场改善熔核偏移的作用更加明显. 之后针对外加磁场和常规点焊情况的不同两层及三层板铝合金板厚组合式样进行了剪切拉伸测试. 结果表明,外加磁场在改善点焊熔核偏移的同时,提高了点焊接头的强度. 因此,外加磁场是一种改善非等厚度铝合金点焊熔核偏移及提高接头剪切拉伸性能的有效方法. 相似文献
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Gang Tie Shen Chunlong National Key Laboratory of AWPT Harbin Institute of Technology Harbin P. R. China Gong Runli Inspection Branch of State Factory Beijing P. R. China 《中国有色金属学会会刊》1998,(3)
1INTRODUCTIONSpotweldinghasbeenwidelyusedinaluminumaloystructuresofspacecraftandaircraftduetoitscharacteristicsoftechnology.... 相似文献
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分析了外加磁场对铝合金电阻点焊接头质量的影响,包括熔核尺寸、接头力学性能和微观组织. 结果表明,外加磁场增大了熔核直径、提高了点焊接头的剪切力和吸收能. 在不同工艺参数下,熔核直径增长在5%~25%,剪切拉伸力可提高10%~30%. 在一些焊接参数下,外加磁场可以降低焊接电流、减短焊接时间,从而提高焊接效率、降低能耗. 外加磁场可促进点焊熔核内等轴晶的生成和细化晶粒.当焊接电流很小或很大、焊接时间过短或过长时,都会降低外加磁场的效应. 因此当对点焊施加外磁场时,应在合理的工艺参数下进行,以最大限度地发挥外加磁场的作用. 相似文献
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在介绍大电阻介质材料的制备及其在铝合金点焊中的应用方法的基础上,以LF21防锈铝合金点焊为例,经金相试样分析及扫描电镜分析,对比研究了在不同的焊接电流下,应用介质材料与未应用介质材料时的熔核形貌、缺陷及组织.结果表明,未加入大电阻介质的点焊熔核均出现气孔和未熔合缺陷;而加入大电阻介质,形核效果良好,有个别小气孔但未出现影响焊点力学性能的未熔合缺陷.此外,加入大电阻介质降低了对焊件表面质量的要求,从而提高了铝合金点焊质量的稳定性;可降低焊接电流,导致较低的电极温度从而提高了电极寿命. 相似文献