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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。
In this paper, by measuring the change of electrical parameters during cutting, the motion of plasma arc anode spot in the cutting of large thickness plate and its influence on double arc are studied. It is pointed out that in addition to the large arc power and the high degree of compression used in the cutting of large thickness boards, it is easy to promote the emergence of double arcs. The anode spot greatly beats in the incision so that the instantaneous working point of the cutting current and the plasma arc load is in a violent fluctuation State, frequent peak current is much larger than the average current, causing the rapid expansion of the arc column, the temperature increases, easy to heat the nozzle increased, the compressed pore wall of the flow layer damage and the local formation of arc channels, but also large thick board cutting One of the important reasons for double arcs. Secondly, the influence of the nozzle potential on the double arc during cutting is also studied. It is pointed out that the potential difference between the arc nozzle and the outlet of the nozzle has a great influence on the double arc. It is easy to control the nozzle potential by simple human control. Based on the experimental study, two double-arc prevention measures are proposed for large heavy plate cutting: (1) Connect the nozzle and the workpiece with a proper resistor to increase the potential of the nozzle and reduce the arc between it and its exit Potential difference between. (2) improve the cutting power, try to improve the steepness of the characteristics of the power supply to reduce the current fluctuations caused by a substantial beating of the anode spot. The test results show that these measures can effectively prevent double solitary, without reducing the cutting ability, for the realization of plasma arc plasma cutting a large thickness, it is very important.