Temperature Characteristics of the Droplet Detaching from the Wire Tip in MIG Welding
Temperature Characteristics of the Droplet Detaching from the Wire Tip in MIG Welding
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MIG焊接焊丝尖端脱离熔滴的温度特性
DOI：
10.2207/qjjws1943.36.1117
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发表时间：
1967
期刊：
影响因子：
--
通讯作者：
K. Fukuda
中科院分区：
文献类型：
--
作者：
K. Ando;K. Nishiguchi;K. Fukuda
在图1和图2所示的特殊电极布置下，用热量法测量了电弧焊中从焊丝尖端分离的熔滴的热含量。Ozawa已经报道了这个问题，我们进一步进行了测试，以了解低导电率和高导电率焊丝的温度特性。图4显示了铜和铝焊丝的结果，图6显示了钢和不锈钢焊丝的结果。对于铝导线，以cal/g表示的热含量Qm在球状转移范围内随着电流的增加而增加，并达到几乎恒定的高值。对于喷雾传递范围，温度估计接近于沸点。在钢丝或不锈钢丝（图6）的恒定丝伸长下，Qm-I的特性曲线如图7所示。对于球状转移范围AB，Qm随着电流I的增加而增加，这与图8中所示的铝的情况类似。在达到最大值之后，Qm随着电流的进一步增加而减小（曲线BCD）Jm的减小与丝尖的类似于锯齿的形成有关，这是低导热率和低导电率的丝的众所周知的特性，并且这表明当丝尖采取类似于锯齿的形式时，液滴可以更容易地分离。图6（a）中的Qm-I曲线可以从上述思想清楚地解释。图8示出了对于特别长的线材延伸的铝线材的Qm-I曲线，并且该曲线示出了与钢丝的趋势相同的趋势。现在我们理解，当线材通过焦耳损失被充分预热时，液滴温度降低到与线材材料的熔点一样低，当焦耳加热可以忽略不计时，它会上升到沸点，而金属丝被足够大电流密度的电弧突然加热。图9、图11示出了根据图11和图12所示的Qm和比熔化速率m（mg/sec）计算的等效熔化电压。4-8.从这些数字中我们可以清楚地估计焦耳加热和阳极加热。
Heat content of the droplet detaching from the wire tip in MIG arc welding is measured calorimetrically under a special electrodes arrangement shown in Fig. 1, 2.Ozawa already reported on this problem and we tested further to understand the temperature characteristics for wires of low and high conductivities.Fig. 4 shows the results for copper and aluminum wires and Fig. 6 those for steel and stainless steel wires. For aluminum wire, the heat content Qm expressed in cal/g increases as the current is increased in globular transfer range and reaches a nearly constant high value. The temperature is estimated to be nearly equal to the boiling point for the spray transfer range.The characteristic curve of Qm-I under a constant wire extension for steel or stainless steel wire (Fig. 6) is shown in Fig. 7. Qm increases as the current I is increased for globular transfer range, AB, which is similar to that of aluminum shown in Fig. 8. After reaching a maximum value, Qm decreases for further current increase (curve BCD).The decrease of Qm is related to the pencil-like forming of the wire tip, which is the well-known characteristic for wires of low thermal and electric conductivities, and this suggests that the droplet can detach more easily when the wire tip takes the pencil-like form. Qm-I curves in Fig. 6(a) can be explained clearly from the above mentioned idea. Fig. 8 shows a Qm-I curve for aluminum wire for an extraordinarily long wire extension, and the curve shows the same tendency as that of steel wire.Now we understand that the droplet temperature decreases to as low as the melting point of the wire material when the wire is preheated sufficiently by joule's loss, and it rises to as high as the boiling point when the joule's heating is negligible and the wire is heated abruptly by arc of sufficiently large current density.Figs. 9, 11 show the equivalent melting voltage calculated from Qm and the specific melting rate m (mg/Amp⋅sec) shown in Figs. 4-8. From these figures we can clearly estimate the joule's heating and the anode heating.