熔化极气体保护焊焊枪的构造

熔化极气体保护焊焊枪的作用是传导焊接电充、导送焊丝和保护气体,按其用途可分为半自动焊焊枪（手提式）和自动焊焊枪（安装在机械装置上）两种。在焊枪内部装有不同孔径的导电嘴,以适应不同直径焊丝的需要,焊枪还具有一个向焊接区输送保护气体的通道和喷嘴,喷嘴是易损件,应该很方便地更换。     

宾采尔焊枪的最新研究成果

介绍了宾采尔焊枪3项最新的研究成果。CO2焊接用陶瓷喷嘴：该喷嘴的陶瓷内芯受到金属外壳强大压应力作用，能在CO2焊接时可靠地使用；施风冷却焊枪：CO2在枪颈中沿螺旋通道盘旋流出，大大提高了CO2与枪颈间的热交换，使焊枪得到了充分的冷却；自保护药芯焊丝焊枪：降低发热并改进了送丝性能。     

焊接机器人送丝系统故障分析及解决方案

焊接机器人送丝系统故障约占机器人总故障率的70%以上,是造成咬边、夹渣、偏焊、大颗粒飞溅及焊穿等焊接缺陷的主要原因,严重制约着企业的生产效率及成本。将送丝系统故障发生部位总结为4段1丝,即焊枪段、枪缆段、送丝机段、外部送丝管段及焊丝段。通过排除法精确定位送丝系统故障的发生位置,从耗材磨损情况、配件老化情况及辅料的质量状态出发,逐段分析送丝系统故障的产生原因并提出相应解决方案,为焊接机器人的高效应用提供有益参考。     

MAG三丝焊工艺试验

MAG三丝焊设计基于分体式的双丝焊枪,在双丝焊枪的正中间加入第三焊丝,利用双丝焊的热量来熔化第三焊丝。针对7 mm焊脚的水平角焊进行了焊接工艺试验。结果表明,MAG三丝焊与双丝焊焊缝质量相当,焊缝晶粒更细小,熔敷效率提高20%,焊接速度更快,显现出了MAG三丝焊的一定优势。     

带延时电路的电流继电器在CO-2弧焊送丝机中的应用

国内外功能比较全面的半自动CO_2气体保护焊送丝机中,都具有一种接触送丝功能,即焊丝的送进不受焊枪上开关的控制,而只靠焊丝能否与工件接触产生电弧电流来决定是否送丝。这种功能给焊接操作提供了较多的方便,而实现这一功能必不可少的控制元件之一,就是电流继电器。下面就我厂批量生产的送丝机中所应用的电流继电器,以及新设计的相应触发延时开关电路进行简要介绍。 1、电流继电器的结构与原理电流继电器结构如图1所示。焊接电缆穿过电流继电器中心孔,当焊丝与工件接触引燃     

螺旋缝埋弧焊管内外自动焊焊枪结构设计

介绍传统焊枪和新设计埋弧焊管内外自动焊焊枪的结构,分析新型埋弧焊枪的工作原理,对比两种焊枪在生产中的应用情况。分析认为:与传统焊枪相比,新设计的埋弧焊枪能始终保证焊丝与导电嘴一侧接触,保证焊接时焊丝的位置稳定,通过风冷可以有效降低焊丝温度,同样工况下提高了焊缝形貌及理化性能结果。新设计的焊枪结构仍存在短板,无法针对多丝焊进行调节;焊接内径较大的焊管时,利用传导机构调节内焊丝位置较容易,管径小时则不易操作。建议与自动化测量技术相结合,根据导电嘴损耗自动调节焊丝位置,避免因忘记手动操作或位置局限难操作等引起的焊丝位置偏离而造成的产品质量问题。     

焊接与切割设备的使用和维修(二十一)--送丝系统、焊枪、导电嘴、喷嘴对焊接质量的影响

阐述了CO2焊中送丝方式应与焊接电源相配合，对电弧自调节作用、弧压反馈送丝方式作了仔细说明，对CO2送丝机的调速电路、焊枪、送丝软管、导电嘴、喷嘴的结构特点及其对焊接质量的影响进行了深入的分析。     

T.I.M.E.高速气保焊性能与应用研究

对T.I.M.E.高速气保焊的原理与性能进行了研究,介绍了保护气体、焊丝伸出长、焊接电源、焊枪设计、送丝机构和焊接效率等方面的特点,并进行了与普通MAG焊对比的焊接性能试验,得出采用高速气保焊工艺所焊试板的各项性能符合标准要求。     

CO_2焊枪结构的改进

我厂曾购进一台NBC-400型CO_2焊机,由于焊枪结构不合理、材料不过关,不能正常使用。原焊枪结构如图1所示。焊丝经送丝导电管1由送丝嘴3送出。送气管里的CO_2气经导气环6上的均匀分布的圆周孔流出,进入金属喷嘴4。导气环6的材质为聚四氟乙烯塑料,起送丝管与送气管之间的绝缘作用。固定套5固     

焊丝校直器在自动焊送丝系统中的应用

自动焊的送丝过程极其复杂,在自动焊的工业化应用中,由于送丝导致的问题如设备停机、焊接缺陷等十分常见。本文研究了焊丝校直器在自动焊送丝系统中的作用,并分别通过检测送丝过程、焊接过程及最终的产品焊接质量,证明了安装焊丝校直器有助于稳定自动焊送丝过程,并通过实际运用解决了困扰自动焊多年的送丝问题,产生了巨大的经济效益,同时为今后自动焊设备送丝系统的研发指明了方向。     

Effect of homogenisation heat treatment on heat affected zone cracking susceptibility.Study of weldability of Inconel 718 cast alloy (3rd Report)

ALW has developed a new tungsten inert gas (TIG) robotic welding process which combines the quality of the TIG process with the productivity of the MIG process. The keystone is the particular configuration of the torch: the weld wire is fed directly into the arc zone, where the temperatures are higher resulting in ‘continuous liquid-flow’ transfer. This configuration also offers the advantage of reduced overall dimensions and greater accessibility of the torch for robotic welding of complex geometries. There is no longer any need to position and direct the weld wire with respect to the torch and the joint to be welded. Hence, the sixth axis of the robot is free.

The applications to date relate to the welding of stainless steel containers, butt and lap welding, carbon steel mechanical parts with intermittent beads in the thin or medium thickness range. Applications on thin, galvanised sheeting, using CuSi₃ wire with no spatter, have been successfully tested in the weld-brazing field, in partnership with the automobile industry. Other applications may include the welding of stainless steels and light alloys for the food and furniture sectors, among others.     

Prediction of dilution in GMA and UGMA stainless steel single layer cladding using response surface methodology

Abstract

This paper describes the use of a variant of GMAW process named as UGMAW (universal gas metal arc welding) process for single layer stainless steel cladding, which makes use of a specially designed torch to preheat the filler wire, using an auxiliary welding power source, before its emergence from the torch. The experimental work undertaken was that of single layer cladding of 12 mm thick low carbon steel with the austenitic stainless steel 316L solid filler wire of 1·14 mm diameter. Dependence of dilution was investigated using four factor five level central composite rotatable design to develop relationship for predicting dilution, which enables to quantify the direct and interactive effects of four numerical factors, namely, wire feed rate, open circuit voltage (OCV), welding speed, electrode stickout and one categorical factor, preheat current. External preheating of the filler wire in UGMAW process resulted in greater contribution of arc energy by resistive heating owing to which significant drop in the main welding current and hence low dilution values were observed. Numerical optimisation was carried out and the optimal solutions generated indicate that for same levels of dilution, higher deposition rates are achievable in UGMAW process, thus making it a good choice for low cost surfacing applications.     

水下机器人局部干法焊接系统的分析

针对核电站优质水下焊接修复需求,研制了一套局部干法水下机器人焊接系统.以DSC微处理器为核心,结合二次逆变主电路,设计了全数字多波形柔性输出的大功率水下焊接电源;采用电枢电压反馈控制、高频斩波脉宽调制及动静密封技术,开发了紧凑型潜水送丝装置;针对焊接局部保护和排渣难题,开发了基于收缩喷管原理的双气帘结构微型排水罩.集成专用水下焊枪、机器人、视觉系统等,搭建水下机器人局部干法焊接试验平台,开展水下焊接试验.结果表明,研制的局部干法焊接系统样机性能可靠,引弧成功率高,焊接过程稳定,焊缝成形美观.     

Welding current prediction in GMAW and UGMAW processes using response surface methodology

Abstract

Among all process variables in gas metal arc welding (GMAW) process, welding current is the most influential variable affecting heat input and weld quality. Its dependence on other process variables in GMAW and universal gas metal arc welding (UGMAW) processes (which makes use of a specially designed torch to preheat the filler wire independently, before its emergence from the torch) has been investigated using four factor five level central composite rotatable design to develop relationship for predicting welding current, which enables to quantify the direct and interactive effects of four numeric factors, namely wire feedrate, open circuit voltage, welding speed and electrode stickout and one categorical factor preheat current. Mathematical models developed show that welding current increased linearly with increaseing wire feedrate and open circuit voltage, whereas it decreased with increasing electrode stickout and preheat current. Numerical optimisation was carried out, and the optimal solutions generated indicate that under the same input conditions higher deposition rates are achievable in UGMAW process.     

Computational fluid dynamics analysis of a wire-feed, high-velocity oxygen fuel (HVOF) thermal spray torch

The fluid and particle dynamics of a high-velocity oxygen fuel (HVOF) thermal spray torch are analyzed using computational and experimental techniques. Three-dimensional computational fluid dynamics (CFD) results are presented for a curved aircap used for coating interior surfaces such as engine cylinder bores. The device analyzed is similar to the Metco diamond jet rotating wire (DJRW) torch. The feed gases are injected through an axisymmetric nozzle into the curved aircap. Premixed propylene and oxygen are introduced from an annulus in the nozzle, while cooling air is injected between the nozzle and the interior wall of the aircap. The combustion process is modeled using a single-step, finite-rate chemistry model with a total of nine gas species which includes dissociation of combustion products. A continually fed steel wire passes through the center of the nozzle, and melting occurs at a conical tip near the exit of the aircap. Wire melting is simulated computationally by injecting liquid steel particles into the flow field near the tip of the wire. Experimental particle velocity measurements during wire feed were also taken using a laser two-focus (L2F) velocimeter system. Flow fields inside and outside the aircap are presented, and particle velocity predictions are compared with experimental measurements outside of the aircap. This work was performed at Sandia National Laboratories, which is operated by Lockheed Martin for the U.S. Department of Energy under contract DE-AC04-94AL85000.     

旁路耦合微束等离子弧增材制造自适应高度控制系统

在xPC Target实时目标环境下,采用旁路耦合微束等离子弧进行增材堆垛试验,探究最大临界送丝速度、焊炬悬空高度和总电压等过程参数之间的关系.通过数据分析得到了送丝速度与总电压的回归模型,进一步在xPC Target系统中创建变送丝和电压反馈相结合的自适应高度调节控制模型,搭建了基于自适应高度调节的旁路耦合微束等离子弧增材制造控制系统,进行了在台阶形基板上的堆垛成形试验和单墙体零件自适应堆垛试验.结果表明,该控制系统能提高增材制造过程的稳定性;优化堆垛高度方向上的成形路径设计;实现复杂形状基板上金属零件的堆垛成形.     

浅谈我国钢制压力容器焊接新技术

针对我国钢制压力容器相对薄弱的焊接领域,如厚壁压力容器、承装腐蚀介质的压力容器和不锈钢复合板压力容器,介绍了我国钢制压力容器的焊接新技术,包括窄间隙多丝埋弧焊、激光-电弧复合热源、带极电渣堆焊、药芯焊丝CO2气保护焊、脉冲TIG焊;分析了焊接新技术在压力容器焊接中的应用,并对未来发展进行展望。     

Underwater robot local dry welding system

To satisfy the demand for good quality underwater welding and maintenance of nuclear power stations, a set of local dry automatic welding systems has been developed. These systems were based on an underwater robot that consisted of a special high-power underwater welding power supply, diving wire feeder, mini drain cap, welding robot, and special underwater welding torch. With a digital signal controller microprocessor as its core and combined with a dual inverter topology, the welding power supply was characterized by full-digital construction and multi-waveform flexible output. A compact diving wire feeding device was designed, based on the armature voltage negative feedback and high-frequency chopping pulse width modulation.This device yielded a high-efficiency seal of the driving motor with the help of dynamic and static sealing technology. To overcome the difficulty of local protection and deslagging in the welding area, a mini drain cap (with a duplexgas structure) based on the principle of the convergent nozzle was designed. The practical tests and the underwater welding experiments revealed that the underwater robotic local dry welding system is quite feasible. That is, the system could strike the arc stably and reliably in the shallow water environment, and formed beautiful welding seams.     

The characteristics of welding currents in a rotating arc lead tandem GMAW process and the weld-seam tracking

Tandem gas metal arc welding (T-GMAW) process shows a high deposition rate that up to three times of the single electrode GMAW,so the welding speed could be significantly increased in this process.However,the majority of this process applications are based on the pre-programmed robotic welding,which does not allow them to track the seam real-time during welding.Rotating arc sensor,sensing the seam position by detecting the changing of welding currents,has been widely adopted in the automatic robot welding process.It is proposed in this paper to integrate the rotating arc sensor with a trailing torch to develop a new approach of rotating arc lead tandem gas metal arc welding (RLT-GMAW) process.The characteristics of the welding currents in the proposed new welding process were firstly studied,and then a self-turning fuzzy control seam tracking strategy was developed for the mobile robot automatic welding.The experimental results showed that the proposed RLT-GMAW process had an excellent seam tracking performance and high welding deposition rate.Even if there were some electromagnetic interactions between the two arcs,the deviation of the welding seam could also be reflected by the fluctuation of the welding currents on the leading arc once the correct welding parameters were selected.Based on the detected deviation,the welding tracking experiments showed that the proposed self-turning fuzzy controller had a good performance for the RLT-GMA W process seam tracking.     

A study on consumable aided tungsten indirect arc welding

A consumable aided tungsten indirect arc welding method has been studied. This method is different from the traditional TIG welding because it introduces an MIG welding torch into the traditional TIG welding system. An indirect arc is generated between the consumable electrode of the MIG welding torch and the tungsten electrode of the TIG welding torch, but not generated between the tungsten electrode of the welding torch and the base metal. Welding current flows from the consumable electrode to the tungsten electrode in the free-burning indirect arc. The consumable aided tungsten indirect arc welding not only rapidly melts the welding wire but also effectively restrains the excessive fusion of the base metal. The welding experiment and the theoretical analysis confirm that this method can obtain a high deposition rate and a low dilution ratio during the welding process.