1,STT Surface Tension TransferNovember 2008表 面 张 力 过 渡 技 术,Michael HuApplication and Product Development Manager of Automation Division of Shanghai Lincoln Electric,2,Basics 基本概念,S.T.T. = Surface Tension Transfer 表面张力过渡Research Began July 1985 1985年开始研究开发Purpose is to develop a welding process which eliminates spatter when use 100% CO2 shielding gas目的是为了开发一种使用CO2保护气体而没有飞溅的焊接方法STT is a Unique GMAW Process一种独特的气保护焊接工艺,3,Basics 基本概念,Neither CC Nor CV既不是恒流源也不是恒压源Based on interactive WAVEFORM CONTROL TECHNOLOGYTM基于交互式波形控制技术Based on High Speed Inverter Technology 基于高速逆变技术Precision Current Controlled Short Arc精密电流控制的短路过渡焊接,4,Advantages 优点,Low spatter 低飞溅量Low fume 低烟尘Low cost Gas 低气体成本Controlled Heat Input 可控制的热输入量All Position 可进行全位置焊接Good Fusion 良好的焊接成型Handles Poor Fit-up 适用较差的接头形式,5,Manual Welding: STT vs Short Arc 手工焊接: 表面张力过渡 vs 短路过渡,Standard GMAW标准的气保护焊接,Surface Tension Transfer表面张力过渡,6,Traditional GMAW 传统 气保护焊接,7,STT Welding 表面张力过渡焊接,8,Standard GMAW标准的气保护焊接,Surface Tension Transfer表面张力过渡,Robotics Welding: STT vs Short Arc 机器人焊接: 表面张力过渡 vs 短路过渡,9,G.M.A.W = Gas Metal Arc Welding 熔化极气体保护焊接MIG/MAG Welding MIG/MAG 焊接MIG = Metal Inert Gas 惰性气体熔化极保护焊MAG= Metal Active Gas 活性气体熔化极保护焊Solid Wire with External Shielding Gas实芯焊丝和外部保护气体DC+ Polarity 直流正接,What is GMAW? 什么是GMAW?,10,Overview of GMAW processes 气保护焊接工艺概述,Consistent Voltage GMAW (CV) 恒压气保护焊接Pulse GMAW (MIG/MAG)脉冲气保护焊接STT (Surface Tension Transfer)表面张力气保护焊接,11,CV Power Source Output 恒压电源输出,Welding Circuit Consists of CV Power Sources with a Wire Feeder 焊接回路由恒压电源和送丝机组成Voltage is Proportional to Arc Length 电压与电弧长度成正比Current Changes Dramatically to Maintain Constant Arc Length 电流动态变化以维持恒定的电弧长度,12,Modes of Arc Transfer 熔滴过渡形式,Short Circuit (Short Arc) Transfer 短路过渡 Globular Transfer 滴状过渡Spray Transfer 喷射过渡,Conventional 常规形式,Waveform Control Technology TM波形控制技术,Pulse Spray Transfer 脉冲喷射过渡Surface Tension Transfer 表面张力过渡,13,Short Arc Transfer 短路过渡,Low Voltages & Low Amperages 低电压&低电流Typically Smaller Wire Diameters 典型的小直径焊丝Typical Shielding Gases Include CO2 , 75/25 Ar/CO2 典型保护气体 100%CO2, 72/25 Ar/CO2The Wire Shorts to Workpiece. 焊丝与工件短路The Voltage = 0 电压为零The Amperage Accelerates Rapidly 电流快速增加Wire Breaks off Producing a Weld Bead and Spatter 焊丝断开产生焊缝和飞溅,14,Short Arc Transfer 短路过渡,15,Low Heat Input低热输入All Position Welding全位置焊接Low Cost低成本Poor Fit Up 适应较差的接头形式,Spatter飞溅大Potential Lack of Fusion容易产生熔合缺陷Limited to Thin Material只适用于薄板材料焊接,Advantages优点,Limitations 缺点,Short Arc Transfer 短路过渡,16,Globular Transfer 滴状过渡,High Voltage & High Amperages高电压和高电流Typically Larger Wire Diameters典型的大直径焊丝100% CO2, 75/25 Ar/CO2 Gas Mix (Lower Cost Shielding Cost) 100%CO2, 75/25 Ar/CO2混合气体(低成本保护气体),17,Globular Transfer 滴状过渡,Ball Forms on the End of the Electrode球形熔滴在焊丝端部形成Before a Short Circuit Occurs, the High Amperage and Gravity Pull the Ball off to form weld and SPATTER在形成短路之前,高电流电磁力和重力将熔滴推离焊丝,过渡到熔池形成焊缝和飞溅,18,Globular Transfer 滴状过渡,Deep Penetration较深的熔深High Deposition高熔敷率Low Cost Gas低成本气体,Excessive Spatter过多的飞溅Flat & Horizontal Only只能进行平焊和横焊,Advantages 优点,Limitations 缺点,19,Spray Arc Transfer 喷射过渡,High Voltages & High Amperages高电压和高电流Typically used with Wire Diameters of .035 and Larger一般使用0.035直径以上的焊丝直径A Minimum of 80% Argon in the Gas Mix使用最少含有80%以上氩气的混合气,20,Spray Arc Transfer 喷射过渡,Sharp Point Forms on End of Electrode在焊丝端部形成铅笔状Fine Droplets Are Directed in a Straight Line From the Wire to Weld Puddle 很细小的熔滴形成一条直线从焊丝过渡到熔池中，形成焊缝。,21,Spray Arc Transfer 喷射过渡,Smooth Weld Bead光滑的焊缝成型Deep Penetration熔深很深High Deposition高熔敷率Little to No Spatter很少或没有飞溅,Potential Undercut容易出现咬边Expensive Shielding Gas保护气体成本高Flat & Horizontal Only只能平焊和横焊,Advantages 优点,Limitations 缺点,22,Stable CV Transfer Modes 稳定的CV过渡模式,Short Arc 短路过渡,Globular Arc滴状过渡,Spray Arc 喷射过渡,WFS (current) Increasing送丝速度（电流）增加,Voltage Range电压范围,23,Surface Tension 表面张力Pinch Forces 电磁收缩力Jet Forces 电弧推力,Forces in Arc 电弧的作用力,24,Surface Tension 表面张力,25,Surface Tension 表面张力,Droplet on wire焊丝上的熔滴,Weld Puddle,26,Surface Tension 表面张力,The small drop is absorbed into the big drop小的熔滴被大的熔滴吸收了,27,Surface Tension and Pinch Forces表面张力和电磁收缩力,Surface Tension Forces 表面张力Wet Droplet to Weld Puddle 润湿熔滴到熔池Pinch Forces电磁收缩力Separate Shorted Electrode from Puddle将短路的焊丝与熔池分离,28,Pinch Force 电磁收缩力,R = Outer Conductor Radius (cm),r = Inner Conductor Radius (cm),Maximum at r=0,29,Jet Forces 电弧推力,Thermal Mechanism 热机械过程Caused by Vaporized and Accelerated Metal in the Anode and Cathode Drop Regions 由在阳极和阴极之间蒸发和被加速的金属粒子产生Complex Phenomenon复杂的现象Very Pronounced at High Currents大电流时非常显著,30,Transition Current 过渡电流,Below Transition Current 低于过渡电流Electrode is Melted 焊丝被熔化Surface Tension Holds Droplet on the Wire表面张力将熔滴留在焊丝端部Above Transition Current 高于过渡电流Droplet is Expelled from Wire and Transferred to Work熔滴被推离焊丝，过渡到工件,31,Transition Current 过渡电流,Pinch Forces Exceed the Surface Tension Forces, Molten Metal is Expelled and Transferred form the Electrode 电磁收缩力超过表面张力，熔化金属被推离焊丝,