【摘要】 本文通过测定切割中电参数的变化,研究了大厚度板切割中等离于弧阳极斑点的运动及其对双弧的影响规律。指出大厚度板切割中除因其使用的电弧功率大,压缩程度高,容易促使出现双弧外,阳极斑点在切口中大幅度跳动,使切割电流和等离子弧负载的瞬时工作点处于剧烈的波动状态,频繁出现的峰值电流远远大于平均电流,引起弧柱急剧膨胀,温度升高,易使喷嘴受热加剧,其压缩孔道壁上的气流层破坏而局部形成电弧通道,也是大厚度板切割中容易出现双弧的一个重要原因。其次本文还研究了切割中喷嘴电位对双弧的影响,指出喷嘴与其出口处弧柱间的电位差大小对双弧有极大的影响。可以对喷嘴电位进行简单的人为控制而影响双弧产生的难易。在试验研究的基础上提出了两项适用于大厚板切割的双弧防止措施:(1) 用适当的电阻器将喷嘴与工件连接起来,以提高喷嘴电位,减小它与其出口处弧柱间的电位差。(2) 改进切割电源,尽量提高电源外特性的陡度,以减小因阳极斑点大幅度跳动引起的电流波动。试验结果证明这些措施既可有效地防止双孤,又不降低切割能力,对于实现稳定的等离子弧大厚度板切割,有很重要的意义。更多还原

【Abstract】 The movement of auode spot and the law of its influence on series-arcing in plasma cutting of thick plates have been studied by measuring the electric parameters during cutting processes. It was indicated that an important cause to produce the series-arcing is the wide jumping amplitude of the auode spot on the kerf wall besides the high power and serious constriction of the plasma arc. The influence of electric potential of plasma nozzle on series-arcing has also been studied.It was shown that the potential difference between the nozzle and the are column at its exit has most important influence and the series-arcing can be ontrolled simply by changing the electric potential of the nozzle. In present paper two new methods for enhancing the ability to prevent the cseries-arcing have been developed. One of them is to control the electric potential of plasma nozzle and the other is to increase the droping steepness of the static volt-ampere characteristic of the power supply, so that the wandering amplitude of the current in the kerf is reduced. Experimental results show that the measures mentioned above may effictively prevent the series-arcing without the reduction of the cutting ability in plasma cutting processes so that they will be significantly important for thick plate cutting.更多还原