机器人空心螺柱旋弧焊枪研制与工艺试验研究

发布时间：2018-04-24 20:24

本文选题：空心螺柱 + 旋弧焊　；参考：《南京理工大学》2017年硕士论文

【摘要】：针对大直径空心螺柱自动焊接需求,在机器人自动焊系统研究的基础上,提出了空心螺柱旋弧焊接方案,设计全新的旋弧自动焊枪,该焊枪包括步进电机单元、电磁式电弧螺柱焊枪主体、气爪单元、径向对称磁场单元和连杆机构,并根据焊枪特点设计了相应的机器人工作站,工作站包括空心螺柱焊枪、六轴工业机器人、柔性焊接平台、拉弧螺柱焊接用电源和旋弧磁场电源,以及相应的控制模块。该工作站可以实现空心螺柱的自动焊接,并提升定位精度、焊接效率和自动化程度。焊枪设计主要包括施加磁场使电弧发生旋转、利用步进电机自动控制螺柱焊拉弧高度、设计气爪夹头、并重新设计焊枪框架结构。焊枪稳定可靠,可以夹持12mm～60mm任意高度,外径在Φ12mm～Φ32mm任意直径的空心螺柱,可以控制拉弧高度在以0.5mm为单位,从0mm～5mm任意调节,径向对称磁场单元可以产生贯穿于螺柱端面的径向对称磁场,使焊接电弧发生旋转,进行旋弧焊接工艺试验。对焊接电弧施加磁场后,电弧形态变化复杂,利用COMSOL Multiphysics构建1:1比例模型,定义材料,模拟磁场在螺柱端面到母材之间的分布情况,并进行粒子、磁场耦合分析,得到不同焊接电流与磁场电流下粒子的运动轨迹,分析得到当旋弧半径大于螺柱半径2mm时可以获得较为优质的焊接接头,并设计了适应该模型的APP,方便进行其他型号螺柱的工艺模拟。通过对各个模块的控制需求分析,设计了利用机器人控制柜直接操控焊枪和焊接工艺的控制方案。其中利用西门子PLC,和EM253模块控制步进电机,NX100控制柜输出信号给PLC,以4位二进制数的形式,0.5mm为单位控制丝杠螺母移动距离,最终控制拉弧高度,同时NX100的输出端子排直接控制电磁阀、焊接电源和旋弧电源的开启与关闭,最终直接通过编写机器人程序完成整个焊接流程。对外径16mm,内径8mm的空心螺柱工艺实验研究,得到最优焊接参数为拉弧高度3mm、预压深度3mm、焊接电流800A、焊接时间为800ms和旋弧磁场电流0.7A,其接头抗剪强度可达到362Mpa,通过工艺对比发现,旋弧磁场应用基本解决了偏弧问题,旋弧磁场电流增加有助于电弧向外扩散的趋势。本研究的主要成果和创新点:在原有焊枪设计的基础上,应用旋弧原理设计了新型自动空心螺柱旋弧焊枪及其控制系统,通过工艺试验,基本解决了空心螺柱偏弧问题,得到焊缝成型美观和抗剪强度高的焊接接头,并根据焊枪结构对旋弧焊接原理进行有限元模拟分析,理清磁场对电弧的作用机理,为其他型号的螺柱工艺试验打下基础。
[Abstract]:In order to meet the requirement of automatic welding of large diameter hollow studs, based on the research of robot automatic welding system, this paper puts forward a scheme of spiral arc welding of hollow studs, and designs a new automatic arc welding torch, which includes step motor unit. The main body of electromagnetic arc stud welding gun, air claw unit, radial symmetrical magnetic field unit and connecting rod mechanism are designed. According to the characteristics of welding torch, the corresponding robot workstation is designed. The workstation includes hollow stud welding gun, six-axis industrial robot. Flexible welding platform, arc stud welding power supply and arc magnetic power supply, and the corresponding control module. The workstation can realize automatic welding of hollow studs and improve positioning accuracy, welding efficiency and automation. The design of welding torch mainly includes applying magnetic field to make the arc rotate, using step motor to automatically control the arc height of stud welding, designing air claw chuck, and redesigning the frame structure of welding torch. The welding torch is stable and reliable. It can hold the hollow studs with arbitrary height of 12mm~60mm and diameter of 桅 12mm ~ 桅 32mm. The arc height can be controlled in units of 0.5mm and adjusted arbitrarily from 0mm~5mm. Radial symmetric magnetic field unit can produce radial symmetric magnetic field through the end of stud, make welding arc rotate, and carry out spiral arc welding process test. After applying magnetic field to welding arc, the variation of arc shape is complicated. The 1:1 proportional model is constructed by COMSOL Multiphysics, the material is defined, the distribution of magnetic field between the end face of stud and base metal is simulated, and the coupling analysis of particle and magnetic field is carried out. The motion trajectories of particles under different welding current and magnetic field current are obtained. When the radius of spiral arc is larger than the radius of stud 2mm, a better welding joint can be obtained. The APP suitable for the model is designed to simulate the process of other types of studs conveniently. By analyzing the control requirements of each module, the control scheme of welding torch and welding process is designed by using robot control cabinet. Among them, Siemens PLC and EM253 module are used to control the output signal of step motor NX100 control cabinet to PLC. In the form of 4-digit binary number, 0.5 mm is used to control the moving distance of the screw nut, and finally the arc height is controlled. At the same time, the output terminal row of NX100 directly controls the solenoid valve, welding power supply and arc power source to open and close. Finally, the whole welding process is completed directly by writing the robot program. The experimental study on hollow studs with outer diameter of 16mm and inner diameter of 8mm shows that the optimum welding parameters are 3mm arc height, 3mm preloading depth, 800A welding current, 800ms welding time and 0.7A current of rotating arc magnetic field. The shear strength of the joint can reach 362Mpa. The application of rotating arc magnetic field solves the problem of arc bias, and the increase of arc magnetic field current is helpful to the trend of arc diffusion. The main achievements and innovations of this study are as follows: on the basis of the original welding torch design, a new type of automatic hollow stud rotary arc welding gun and its control system are designed based on the principle of rotary arc, and the problem of hollow stud arc deviation is basically solved through technological tests. The welding joints with beautiful weld formation and high shear strength were obtained, and the principle of spiral arc welding was simulated by finite element method according to the welding torch structure. The mechanism of magnetic field acting on arc was clarified, which laid the foundation for other types of stud technological test.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG409

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