7.2等离子弧切割（课件）-《焊接方法与工艺》同步教学（高教版）

等离子弧切割 Process Variables Hypertherm, Inc. Copyright 2001 1 内容提要 电流 切割能力 气体要求 纯度要求 流量 等离子气 - 空气 - 氮气 - 氩气-氢气 - 氧气 屏蔽气（保护） 割炬高度 穿孔高度 切割高度 割炬高度控制 切割速度和弧压 切割质量的识别 最佳切割质量的定义 切割外观 切割参数表 切割方向 切割面现象诊断 挂渣 - 低速挂渣 -高速挂渣 - 上端口挂渣 切割面倾斜 -切割面倾斜问题 - 纠正方法 割缝宽度 后拖线 后拖线的识别 切割圆形 Process Variables Hypertherm, Inc. Copyright 2001 2 安培 (电流强度) 安培 – 电路中电子流量（每秒钟通过的电子量）的计量单位。 对某一确定厚度的材料, 如切割电流增大，切割速度必须相应提高。 对某一确定厚度的材料, 如加大切割电流，挂渣将会减少。 对某一确定厚度的材料, 选择较低电流切割，通常能获得较好的切面质量以及上口质量。 正常情况下消耗件使用寿命为低电流消耗件高于高电流消耗件，在使用氧气切割时尤其显著。 Process Variables Hypertherm, Inc. Copyright 2001 3 Selecting the correct amperage/consumable set. Once the correct plasma gas has been chosen, it remains to determine the current level and consumable set to be used. Most consumable sets are designed to run at a fixed current level over their entire operating thickness range. The best process for the job often depends on the customer requirements. Are you looking for a perfect edge finish, or are you willing to sacrifice angularity for increased speed? A good first place to look is in the operating manual. What is the thickness range for a given process. Most processes have a sweet spot that is, not surprisingly, in the center of their overall thickness range. Materials that are on the low end of a consumable sets range will usually have decreased edge quality and angularity, and you may be better served to select a lower current set for the job. Materials on the high end of the range will usually cut just fine, but perhaps with more dross and at a slower speed than a higher amperage consumable set, if one is available. By applying a speed Vs. quality equilibrium argument to the type of steel being cut, it should be mostly straightforward to determine what the best choice is. A good trial and error method is to either start at the highest current process or the lowest, and simply make trial cuts until you have found the process that meets your needs. 切割能力 所有等离子切割装置都规定有最大切割厚度和最大穿孔厚度。 Process Variables Hypertherm, Inc.