【作者】 左振龙；

【导师】 唐新华；

【作者基本信息】 上海交通大学 ， 材料加工工程， 2012， 硕士

【摘要】 目前窄间隙熔化极气体保护焊(NG-GMAW)普遍存在侧壁熔合不足的问题,针对此问题,本文在充分调研的基础上,经过分析研究认为通过调整焊丝伸出端与侧壁的夹角,以减小电弧与侧壁的距离,可在一定程度上改善侧壁融合问题,从而提出一种电弧摆动式窄间隙GMAW焊接技术。其基本原理是以步进电机直接驱动导电杆做周期性正反转运动,导电杆末端具有一定的弯角,其与导电嘴相连,焊丝从导电嘴送出后在坡口内引弧,由导电杆的周期性摆动带动电弧在坡口内作往复运动。焊接过程中采用热输入调节范围较宽的MAG焊接方法,以达到坡口两侧壁熔透均匀、增加工艺适应性的目的。本文首先基于CAE方法指导,设计制造了一种新型的电弧摆动式窄间隙GMAW焊枪。设计过程着重考虑了保护气管路、冷却水回路和焊枪绝缘性能对焊枪设计的要求,提出了四种保护气管路方案,利用ANSYS Fluent分析并确定了保护气管路的设计。在完成焊枪设计制造的基础上,分别采用正交试验和单因素试验方法研究了电弧摆动参数对焊缝成形的影响程度及其影响规律,并在试验过程中通过对焊接电压和电流信号的采集和分析,研究了电弧摆动对焊接稳定性的影响,最后通过多层单道窄间隙焊接试验,验证了电弧摆动式窄间隙焊枪设计思想的可行性。试验结果表明:电弧摆动式窄间隙焊枪焊接时气体保护效果良好,冷却水可保证焊枪长时间工作,焊枪绝缘可靠完全避免了侧壁起弧。研究表明:电弧的摆动速度和摆动角度是获得较宽焊缝的两个关键因素,为了获得成形一致的焊缝,电弧的摆动速度与侧壁停留时间必须配合好,否则会出现S形焊缝;焊接电压和电流信号分析表明,电弧摆动式窄间隙焊枪对于熔滴过渡有一定影响,但是仍能够保证焊接过程的稳定性;多层单道焊的试验结果表明,在电弧摆动参数合适、焊丝末端在窄间隙坡口中的空间位置得以精确控制条件下,可获得侧壁熔合良好,表面成形均匀的焊缝,这为该工艺的进一步研究奠定了一定基础。更多还原

【Abstract】 A problem of penetration at both groove sides is widespread in the application of Narrow Gap Gas Metal Arc Welding (NG-GMAW). After a study and analysis of lots of research achievements on this issue, it`s found that the penetration at groove sides can be improved to some extent by regulating the angle between welding wire tip and groove sides to decrease the distance between arc and groove sides. So a process of NG welding with arc-swing is proposed as a solution, which utilizes one stepper motor to drive a conductive rod. A part bended in an angle connects the conductive rob and contact tube. Welding wire gets though the tube into the groove and ignites. Because of periodic motion of the conductive rob in clockwise and anticlockwise, the arc swings between groove sides. In order to get proper and uniform penetration and high-adaptive process, MAG welding is applied due to its wide range heat input.Firstly, based on the CAE results, a new NG-GMAW torch with arc -swing is developed. The shielding gas nozzle, cooling water cycle and insulation of conduct tube are taken into consideration. With the assistance of ANSYS Fluent, a proper shielding gas nozzle solution is chosen. Orthogonal test and signal factor test are carried out to study the influence of swing parameters on appearance of weld. The data of welding current and voltage are acquired to study the influence of swinging arc on welding stability. At last a multi-layer single pass welding test is carried out to verify the feasibility of the process.The test results indicate that the shielding gas is sufficient, the cooling system can guarantee the torch for long-time-work, and the insulation is reliable for avoiding arc ignition between torch body and groove side-walls. Swinging velocity and swinging angle are key factors for getting wide weld beam. The swinging velocity and side holding-time should be well-matched in order to get uniform weld, otherwise an S-shape weld will occur. Analysis of welding current and voltage shows that the swinging arc has a little influence on the droplet transfer, but the stability of welding process can be guaranteed. The result of multi-layer with single pass welding test shows that a unified penetration on groove sides can be obtained under condition of accurately controlled wire tip position and proper welding parameters, which lays a certain foundation for further research of the process.更多还原