水中超声频脉冲等离子弧切割方法及工艺研究.pdf

江苏科技大学
硕士学位论文
水中超声频脉冲等离子弧切割方法及工艺研究
姓名:黄婧芝
申请学位级别:硕士
专业:材料加工工程
指导教师:王加友
2011-03-20
摘要

摘要
高效、高质量、低成本,是现代等离子弧切割技术的发展方向。水中等离子弧切
割具有切割效率高,热变形小,切割时噪音低、粉尘少、弧光辐射低等优点,因此在
实际工业中得到了广泛应用。但是水中等离子弧切割也存在着一些不足。首先,水中
等离子弧切割一般使用直流电源,存在着电弧压缩程度不够、轴指向性不好的局限性,
因此切口成形不够好。其次,水中切割存在着切割面倾斜角过大、挂渣不容易清除、
切口硬度偏高等质量问题。
本文基于干式超声频脉冲切割原理,构建了水中超声频脉冲切割系统,将超声频
电源与等离子弧切割电源并联,实现了对等离子切割电弧的超声频脉冲调制。为了分
析水中超声频脉冲和不同等离子气的工艺效果,分别在干式和湿式条件下,进行了空
气和氧气等离子切割试验,并且每种试验条件下都进行了直流切割以及超声频脉冲切
割。试验过程中,首先对切口成形进行比较,包括上下切口宽度、左右侧倾斜角、左
右侧平直度以及切口挂渣;其次测量了切口硬度,并观察了热影响区显微组织;最后
探讨了组织变化与硬度变化之间的关系。
试验结果表明:超声频脉冲的调制作用,使等离子弧切割切口成形明显改善。以
水中氧气等离子弧切割低碳钢为例,当切割速度为 60cm/min 时,下切口宽度、右侧倾
斜角、右侧平直度的最大改善率分别达到了 %、%和 65%。同时,水中超声频
脉冲的作用,减少了切口挂渣,并且在空气等离子弧切割时改变了熔渣形态。然而,
脉冲幅值对切口挂渣的影响不大。超声频脉冲的作用还使得水中切割时切口硬度降低,
热影响区宽度降低、晶粒变细小。

关键词:水中等离子弧切割;超声频脉冲电弧;切口成形;切口硬度;切口显微组织






I
Abstract
Abstract
The modern plasma arc cutting technology developing direction is towards to efficiency,
high quality and low cost. With the advantages of high efficiency, low thermal distortion and
low noise, little dust and low arc radiation, underwater plasma arc cutting technology has
been widely used in industry. However, there’re some disadvantages in underwater plasma
arc cutting. Firstly, a dc power supply is generally employed by underwater plasma arc
cutting which leads to undesirable cut shape because of the limitation of insufficient
compression degree and inclined axial direction. Secondly, quality problems such as wide
bevel angle, tough dross clear and higher hardness occur since the cutting process is
proceeding under the water.
This paper constructed an underwater system based on the principle of dry ultrasonic
frequency pulsed plasma arc cutting. Therefore, the ultrasonic frequency pulsed modulation
of the arc was realized by paralleling an ultrasonic frequency pulse generator with an
ordinary cutting power supply. To analyze the effects of water and ultrasonic frequency