共查询到19条相似文献,搜索用时 328 毫秒
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针对板管间接点焊过程中焊接变形较大,引起接头质量难以保证的问题.通过采集电极位移曲线,研究板管间接点焊过程中膨胀量和变形量的变化规律,分析不同焊接工艺参数(焊接电流、电极力和焊接时间)对该点焊过程的影响.结果表明,板管间接点焊焊接阶段,膨胀过程与变形过程相互耦合;保持阶段,在电极力作用下,焊接变形进一步加大,最大变形量随着电极力的增大和焊接热输入的增多而线性增加.发生喷溅时,电极位移曲线出现阶梯状畸变,可利用位移曲线斜率的变化评判该点焊的喷溅现象.研究结果为板管间接点焊过程在线监测与质量控制提供理论指导. 相似文献
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利用改进的交流电阻点焊监控系统采集电极位移和焊接电流,经分析认为电极位移曲线上的波动是由50 Hz的交流电阻热脉冲引起的.利用电阻点焊中的洋葱环现象分析了电极位移波动特征的机理,认识到电极位移在熔核形成前以热膨胀为主,在熔核形成后以相变膨胀为主,并且都具有波动特征.利用焊接电流曲线提供的晶闸管触发角和导通角依次计算功率因数角、动态电阻和动态电阻热.通过位移波动周波峰值与动态电阻热的对比分析,发现位移波动周波峰值在点焊过程中对热膨胀与相变膨胀有较强的敏感性,能用来反应熔核形成过程的不同阶段. 相似文献
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为了研究电阻点焊接头质量,分析了铝合金2A12电阻点焊过程中的电极力、电极位移和焊接电流三组动态数据,并绘制了动态数据三曲线图.结果表明,在焊接过程中合格焊点的电极力曲线变化情况是:开始有轻微下凹现象,然后是小幅增长并伴随轻微波动,最后有向下倾斜的趋势,每个阶段不足或过度,则有不合格焊点产生.电极位移曲线的上升率直接与能量供应率有关,电极位移最大时刻与加载锻压力时刻之间的曲线形状与金属熔化量和软化区大小有关. 相似文献
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本文介绍了一套点焊过程电极压力测试装置,并对不同焊接参数和焊接条件下的点焊过程静态电极力及 动态电极压力特性曲线进行了分析,实验结果表明,利用该测试装置能够有效地测取点焊过程的静态及电极压力,并可用于点焊过程质量控制。 相似文献
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铝合金点焊热膨胀电极位移法质量实时控制的研究 总被引:1,自引:0,他引:1
对热膨胀电极位移法在铝合金点焊质量实时控制方面应用的可行性进行了研究。利用自行研制的三相直流波式点焊实验装置,采用闭环反馈控制,对1.0mm+1.0mmLF6铝合金进行了试验,试验表明,系统对网络电压波动,电极压力波动、电极磨损以及焊点分流等民产生的影响能够给予有效补偿。 相似文献
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《Science & Technology of Welding & Joining》2013,18(2):140-145
AbstractElectrode displacement has been used to monitor resistance spot weld quality for long, but the fluctuation of the electrode displacement has not been well studied. This paper analysed the mechanism of the displacement fluctuation by collecting the welding current and electrode displacement during welding process and extracted the incremental pulse expansion of the electrode displacement, which was named as the displacement fluctuation peak. Through metallurgical experiments, the relationship of the displacement fluctuation peak with the weld nugget growth during resistance spot welding process was analysed. The whole process can be divided into four successive stages, and five characteristic points of the displacement fluctuation peak curve were selected to online predict the weld quality. The variation in the displacement fluctuation peak curve under different welding currents was studied, and the results showed that the displacement fluctuation characteristics can be used to effectively evaluate the weld quality. 相似文献
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针对电阻点焊车间生产,开发了一套点焊过程动态数据采集装置,用以采集和分析点焊过程喷溅行为的动态特征.利用系统对试验室环境下的点焊过程进行数据采集,分析了焊接电流、电极力、焊件表面状态、小边距及分流影响下喷溅的动态电阻曲线特征.结果表明,低碳钢点焊过程喷溅发生时,其动态电阻及其变化率曲线形式、峰值的大小、峰值点到达时刻和停留时间、峰值下降量等都有所不同;曲线在不同阶段有不同程度的突变,前期突变程度较大,后期较为平缓;提取的喷溅动态特征参量为动态电阻曲线及其变化率曲线的不同程度突变. 相似文献
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《Science & Technology of Welding & Joining》2013,18(4):480-487
AbstractAlthough there have been a number of investigations on monitoring and controlling the resistance spot welding (RSW) of low carbon galvanised steels, those of advanced high strength steels (AHSS) are limited. A data acquisition system was designed for monitoring weld expulsion via the measurement of voltage, current, electrode force and displacement and the calculation of resistance. The dynamic resistance, electrode force and tip displacement were characterised and correlated with the phenomenon of expulsion during RSW of dual phase (DP) steel using an ac welder. Two control strategies for DP600 spot welding were proposed on the basis of the rate of change in the dynamic resistance and the electrode force. 相似文献
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《Science & Technology of Welding & Joining》2013,18(6):431-436
AbstractAlthough there have been many investigations into monitoring and control of resistance spot welding (RSW) of sheet metal having a thickness greater than 0.5 mm, that of thinner components has rarely been investigated. Monitoring of expulsion in a small scale RSW process was carried out via measurement of voltage, electrode displacement, and force change during the welding current pulse. It was found that electrode displacement increased steadily during the current pulse for an expulsion free weld. For welds with visible expulsion, the electrode voltage had a small but readily observed spike; the electrode displacement showed a dip or a decrease in total amplitude; the force change during a welding cycle was of greater magnitude. Since the system uses a constant current power supply, the voltage increase corresponds to an increase in dynamic resistance associated with the expulsion event. It was also observed that the magnitude of the electrode displacement dip was directly related to the volume of expelled material. The force change is a relatively sensitive indicator for use in expulsion detection. Of the three signals, detection of the voltage spike is the most readily implemented method for monitoring expulsion in small scale RSW. It was also shown that, owing to the small magnitudes of the forces and displacements, careful design of the welding system is necessary to ensure that unwanted vibrations do not interfere with the process signals. 相似文献
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为提高电阻点焊的控制精度和焊接质量,根据电阻点焊过程的特点和要求,通过集成变论域、人工神经网络和模糊控制技术,提出了基于变论域电阻点焊模糊人工神经网络控制方案,开发了四层模糊神经网络结构,分析了计算过程,推导了四层模糊神经网络各层的计算方法和计算公式,研究了输入输出变论域伸缩因子的确定方法,定义了输入变量的7个模糊子集和输出变量的13个模糊子集,确定了49条模糊控制规则,研究开发了一种电阻点焊变论域模糊人工神经网络控制器,结合实际产品的设计开发进行了试验研究与分析,证明了变论域电阻点焊模糊神经网络控制方法的优越性. 相似文献
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Poor quality of resistance spot welding (RSW) often causes quality issues like structural integrity and noise in the car body assembly. Research activities for reliable monitoring methods of RSW quality have therefore been extensive. So far, most of the monitoring methods found in literature are good for off-line utilization only and thus very expensive to apply. This paper introduces into a real-time and in-situ RSW quality monitoring method, which takes the input electrical impedance of the welding system as the monitoring signature. This signature is obtained by probing and processing the input voltage and current throughout the welding process. As input impedance characterizes a dynamic system, its variation with time reveals the conditions of the welding process which result in the final weld quality. By recognizing the pattern of the real part by an artificial neural network, we demonstrate that the weld quality could be classified non-destructively and automatically. Due to the fast signal collecting and processing, the quality monitoring is finished almost in real-time, i.e., classification can be completed before the next welding process is started. Another feature of the method is being in-situ because monitoring action does not jeopardize the welding operation or alter any of the welding parameters in general. 相似文献