STT 焊接工艺培训

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Surface Tension 表面张力
R Pin Pout
g
Pout
Pin - Pout = 2 g R
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Pin
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Surface Tension 表面张力
Droplet on wire
焊丝上的熔滴
Weld Puddle
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Surface Tension 表面张力
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
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Short Arc Transfer 短路过渡
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Short Arc Transfer 短路过渡
Advantages优点
• Low Heat Input
• 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
FAnode FCathode
的金属粒子产生
• • • • Complex Phenomenon
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
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Short Arc Transfer 短路过渡
• • • • • • • Low Voltages & Low Amperages 低电压&低电流 Typically Smaller Wire Diameters
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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
Limitations 缺点
• Spatter
低热输入
• All Position Welding
飞溅大
• Potential Lack of Fusion
全位置焊接
• Low Cost
容易产生熔合缺陷
• Limited to Thin Material
低成本
• Poor Fit Up
只适用于薄板材料焊接
STT Surface Tension Transfer
November 2008
表 面 张 力 过 渡 技 术
Michael Hu Application and Product Development Manager of Automation Division of Shanghai Lincoln Electric
-
的焊丝与熔池分离
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Pinch Force 电磁收缩力
1.45x10-7 P=
I2(R2-r2)
p R4
PSI
I
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r = Inner Conductor Radius (cm) R = Outer Conductor Radius (cm)
Maximum at r=0
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Jet Forces 电弧推力
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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
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/CO2 The Wire Shorts to Workpiece.
焊丝与工件短路
The Voltage = 0
电压为零
The Amperage Accelerates Rapidly
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
-
表面张力将熔滴留在焊丝端部 • Above Transition Current 高于过渡电流
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
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Modes of Arc Transfer 熔滴过渡形式
Conventional 常规形式
• Short Circuit (Short Arc) Transfer 短路过渡 • Globular Transfer 滴状过渡 • Spray Transfer 喷射过渡
• 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
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Advantages 优点
1. Low spatter 低飞溅量
2. Low fume 低烟尘
3. Low cost Gas 低气体成本 4. 5. 6. 7. 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
复杂的现象
Very Pronounced at High Currents
大电流时非常显著
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Transition Current 过渡电流
Current 电流
Pulsed脉冲
80 Amps
410 Amps
• Below Transition Current 低于过渡电流 Electrode is Melted 焊丝被熔化 Surface Tension Holds Droplet on the Wire
The small drop is absorbed into the big drop
小的熔滴被大的熔滴吸收了
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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
• Expensive Shielding Gas
熔深很深
• High Deposition
保护气体成本高
• Flat & Horizontal Only
高熔敷率
• Little to No Spatter
只能平焊和横焊
很少或没有飞溅
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Stable CV Transfer Modes 稳定的CV过渡模式
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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
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Manual Welding: STT vs Short Arc 手工焊接: 表面张力过渡 vs 短路过渡
Surface Tension Transfer 表面张力过渡
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Standard GMAW 标准的气保护焊接
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Traditional GMAW 传统 气保护焊接
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STT Welding 表面张力过渡焊接
适应较差的接头形式
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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)
• DC+ Polarity 直流正接
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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 GM接
•STT (Surface Tension Transfer)
表面张力气保护焊接
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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
Voltage Range
Spray Arc 喷射过渡
电压范围
Globular Arc滴状过渡 Short Arc 短路过渡 WFS (current) Increasing
送丝速度（电流）增加
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Forces in Arc 电弧的作用力
• Surface Tension 表面张力 • Pinch Forces 电磁收缩力 • Jet Forces 电弧推力
• 一种独特的气保护焊接工艺
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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
• Flat & Horizontal Only
高熔敷率
• Low Cost Gas
只能进行平焊和横焊
低成本气体
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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
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。
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Spray Arc Transfer 喷射过渡
Advantages 优点
• Smooth Weld Bead
Limitations 缺点
• Potential Undercut
光滑的焊缝成型
• Deep Penetration
容易出现咬边
磁力和重力将熔滴推离焊 丝,过渡到熔池形成焊缝和 飞溅
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Globular Transfer 滴状过渡
Advantages 优点 • Deep Penetration Limitations 缺点 • Excessive Spatter
较深的熔深
• High Deposition
过多的飞溅
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Robotics Welding: STT vs Short Arc 机器人焊接: 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
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What is GMAW? 什么是GMAW?
• G.M.A.W = Gas Metal Arc Welding