共查询到19条相似文献,搜索用时 66 毫秒
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根据流体的质量、动量、能量守恒方程,建立了穿孔等离子弧焊接过程中的等离子电弧三维数学模型,用磁矢量法求解磁场问题.模型包括了一部分喷嘴和钨阴极,小孔也被包含进模型中.利用ANSYS有限元分析软件求解模型,得到等离子电弧的温度分布,以研究等离子弧焊中电弧反翘现象.结果表明,等离子电弧反翘随小孔尺寸的增大而减弱,电弧尾焰随小孔尺寸的增大而增强;而适当的增加焊接速度以使小孔轴线与电弧轴线之间形成一定的偏差是形成等离子电弧反翘现象的必要条件;焊接电流主要是通过改变小孔尺寸而对电弧反翘产生影响. 相似文献
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根据受控脉冲穿孔的控制策略,研制出等离子弧焊接(PAW)小孔状态的检测与控制系统,采用等离子弧尾焰电压作为表征小孔状态的传感检测信号,对不同焊接电流作用下的焊接过程进行实时监测,系统可以同时采集焊接电流和尾焰电压信号,并对信号进行分析、处理,建立了焊接电流、尾焰电压和背面熔宽三者之间的定量关系曲线.结果表明,尾焰电压信号能够迅速准确地反映出小孔状态和焊缝背面熔宽.根据检测试验得到的数据,建立穿孔型PAW焊接闭环控制系统,通过对普通平板和改变散热条件工件进行闭环控制焊接试验,获得了适当的焊缝背面熔宽及良好的焊缝质量,证明了该系统运行稳定、可靠. 相似文献
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以5 mm厚的5A06铝镁合金板材为主要研究对象,焊缝的正面熔宽和背面熔宽为成形特征参数,通过正交试验确定焊枪行走角变化对焊缝成形影响的显著性,从能量传递的角度研究了焊枪行走角的变化对等离子弧穿孔立焊焊缝成形产生影响的机理.结果表明,焊枪行走角对焊缝成形的影响在焊接电流和离子气体流量之间;焊枪与试板垂直时正面熔宽最大,而随着行走角的减小,焊缝背面熔宽逐渐增大.焊枪行走角的改变使熔池正面的能量密度以及背面最高温度截面和最大熔宽截面的相对位置发生变化,对焊缝背面熔宽的影响可归结于厚度方向不同截面热源位置的偏离与工件厚度导致的传热滞后之间相互作用的结果. 相似文献
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基于等离子穿孔型弧焊(K-PAW)的焊缝成形结构特点,通过对多种不同的热源作用模式进行比较,获得了适合K-PAW焊接成形工艺的体积热源组合式作用模式。把组合式模式应用到K-PAW焊接成形热过程中的SYSWELD软件有限元数值模拟分析中,计算了不锈钢K-PAW焊接工艺中的温度场及成形焊缝的结构尺寸大小,结果表明了所采用热源模式的准确性。 相似文献
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A new kind of control system for keyhole plasma arc welding (K-PAW) was developed based on the computer and the Graphics Language--LabVIEW. It can set and output the required current waveforms with desired decreasing slopes so that the corresponding "opening and closing" of keyhole can occur periodically. With this control strategy of welding current waveforms, the workpiece is fully penetrated while no burn-through Occurs. Keyhole plasma arc welding experiments were conducted to verify the stability and reliability of the developed system. 相似文献
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试验采用光、声信号检测设备,对1.8 mm镀锌钢板的CO2激光焊接过程中的蓝紫光信号、红外辐射信号、可听声信号进行了高速采集,对比激光深熔焊与热传导焊过程中三路信号的联系与区别,分析研究了激光深熔焊过程的小孔与等离子体产生过程的瞬态行为.结果表明,等离子体与小孔并不总是同时产生,等离子体要先于小孔产生,热传导焊过程中也可能存在等离子体,在试验条件下,等离子体在激光作用于工件后3~4 ms产生,稳定的小孔在焊接后约14 ms后形成,并且激光焊接中产生等离子体的激光功率密度阈值要小于产生小孔的阈值. 相似文献
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During stable keyhole plasma arc welding, the pilot arc and the transferred arc exist at the meantime, and the arcs can be considered as a composition of two parts inside and outside the nozzle, respectively. Under the mechanical constriction and thermal contraction effects, the inside arc has certain arc length, electron density and arc profile etc. inducing constant tungsten-to-nozzle voltage. However, the arc outside the nozzle diverges at about 5 degrees and has certain characteristics similar to the free arcs. The nozzle-to-workpiece voltage (NTWV) depends mainly on the length of the arc, which gets bigger as increasing of the weld penetration and keyhole size. The NTWV sensor is developed for monitoring NTWV in real time. The welding experiments are designed to get different penetrations and keyhole sizes. It is found that as the weld penetration and the keyhole size increase, NTWV also increases linearly. The NTWV signals can be used as the feedback variable in automatic control of keyhole plasma arc welding. 相似文献
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The key problem for numerical simulation of plasma arc welding (PAW) process is to develop a suitable and adaptive volumetric heat source mode which reflects the physical characteristics of keyhole PAW. To this end, the keyhole geometry under different PAW process conditions must be predicted. In this paper, a mathematical model for determining the keyhole shape is developed with considering the mass and momentum conservation of the in-keyhole plasma jet as well as the pressure equilibrium at the plasma jet/liquid metal boundary. A suitable heat source model related to the keyhole shape is applied to the calculation of PAW weld dimensions. The predicted results are in good agreement with the experimental ones. 相似文献
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一种新型等离子小孔焊接熔透闭环控制系统 总被引:2,自引:0,他引:2
建立了以电流和等离子体气流为控制变量的等子体小孔焊接熔透闭环控制系统,采用小波方法从焊接电弧电压信号中实时、准确地提取熔池穿孔信息,通过对2个参量的协调控制,成功地实现了“一脉一孔”的焊接工艺。实验表明,该系统不仅显著地提高了电弧穿透力,.能够有效地对10mm厚不锈钢进行小孔型焊接,而且具有良好的快速响应性能,成功克服了3-6mm厚度渐变及附跃变化带来的扰动,实现连续、稳定、可靠的较厚板穿孔焊接。 相似文献
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Modeling the keyhole shape and dimension in plasma arc welding 总被引:1,自引:1,他引:0
It is of great significance to model the keyhole shape and dimensions to optimize the plasma arc welding process parameters. In this study, through employing a combined volumetric heat source mode, the weld pool in keyhole plasma arc welding is determined firstly, and then the dynamic force-balance condition on the interface between the plasma jet and the molten metal is dealt with in describing the keyhole formation inside the weld pool. The effects of welding current on the shape and size of keyhole are numerically analyzed. The sharp transformation from a partial keyhole to a full-penetration keyhole is quantitatively demonstrated. 相似文献
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Numerical analysis of keyhole shape and keyhole establishment time is of great significance for selection and optimization of the process parameters in keyhole plasma arc welding. In this paper, a three-dimensional transient model is developed to analyze the evolutions of keyhole shape and keyhole establishment time in continuous current plasma arc welding process. Firstly, a combined volumetric heat source model is used to simulate the transient variation of temperature field. And then the surfaced formation equation is adopted to calculate dynamic features of the keyhole shape and keyhole establishment time inside weld pool, in which the force action on weld pool surface is considered. Experiment is conducted to validate the numerical simulation results. The predicted keyhole size and keyhole establishment time are in agreement with the experimental measurement. And the calculated fusion zone geometry is consistent with the measured one. 相似文献