【作者】 张红兵；

【导师】 黄石生；

【作者基本信息】 华南理工大学 ， 材料加工工程， 2010， 博士

【摘要】 双丝脉冲MIG高速焊技术不仅可以提高焊接速度,而且可以加深熔深,增强焊缝韧性,减少焊缝的气孔现象,以其高效优质而成为国内外焊接领域的研究热点。双丝焊不是单丝焊的简单堆砌,传统的集中控制式焊接系统及分立的焊接辅助设备无法满足双丝焊精确协同控制和自动化焊接的需要。分布式控制系统是双丝脉冲MIG高速焊的理想系统架构。其设计思想是,每个焊接设备,如焊接电源、送丝机、行走机构、冷却水箱、储气罐和手动控制盒等,都设计为可独立求解局部问题的嵌入式智能控制单元,它们通过现场总线共享焊接过程信息,并籍此严格按照时序紧密协作共同完成双丝焊过程。这种架构既解决了双丝焊的协同控制问题,也提高了焊接自动化水平。焊接智能控制单元是硬实时嵌入式系统,它包括数据库、控制、环境反应和通信四大模块,本文从硬件、软件和控制算法三个方面对其研究。以ARM为嵌入式系统的核心设计了具有CAN总线通信能力的数字化弧焊逆变电源和送丝机。ARM的数字化PWM发生器提高了弧焊逆变电源和送丝机的静态特性和动态响应能力。采用嵌入式实时多任务操作系统μC/OS-Ⅱ可以提高弧焊逆变电源和送丝机等焊接设备的异常事件的响应速度和软件可靠性。将焊接过程的所有内容划分为不同的任务,并定义了任务的优先级别。重要的任务优先级别高。为避免多个任务同时对同一个共享资源的访问,引入信号量以确定共享资源的访问机制。重要任务将处理数据的结果以消息邮箱的形式传递给其他非重要的任务以提高数据处理速度。CAN总线是焊接设备共享信息的通信媒介。开发了用于焊接设备信息交互的焊接通信协议,为焊接设备的开放性、互操作性与互换性奠定了基础。采用全双工方式的RS-422总线构建了双丝脉冲MIG高速焊系统中主从弧焊逆变电源之间的局域高速总线,并定义了完整的通信协议。研究了模糊逻辑控制技术在双丝焊中的应用。以峰值弧压偏差和偏差变化率为输入量,以脉冲基值时间为输出量,采用模糊智能控制器控制双丝焊过程中的弧压从而保持弧长的稳定。采用Fuzzy-PID控制器和模糊推理思想,不断检测送丝速度,根据偏差和偏差变化率,对PID控制器的三个参数进行在线整定,使送丝机具备快速的动态响应能力和良好的恒速效果。构建了双丝脉冲MIG高速焊分布式控制系统并以此为基础进行了大量的试验。焊接设备通信正常并能紧密配合地完成自动焊接过程。双丝协同控制效果明显,主从机电弧的脉冲相位满足设计要求。弧焊逆变电源动、静态特性优良,焊接过程弧长稳定,焊接速度快、效率高。更多还原

【Abstract】 Tandem arc pulsed MIG high-speed welding technology can not only improve welding speed, deepen the melting pool depth, enhance the weld seam toughness, but also decrease porosity of weld joint. It becomes the research focus in the field of welding because of its efficient and high quality. Double wire welding is not simple combination of two single wire weldings. The traditional direct digital control system and discrete auxiliary equipments can not meet the need of precise coordination control and automation welding of double wire welding.A distributed control system is ideal system architecture for tandem arc pulsed MIG high-speed welding. The design idea is that, every welding equipment, such as welding power source, wire feeder, running gear, water cooling tank, gasholder and manual control box, is a embedded intelligent control unit with the ability of solving the local problems. They share welding process information by fieldbus and closely cooperate with each other to complete double wire welding process. The system architecture can not only solve the problem of coordinated control, but also improve the welding automation level. Welding intelligent control unit is a embedded realtime system. It includes database, control, environmental reaction and communication modules. The paper will research its hardware, software and control algorithm.Digital arc welding inverter and wire feeder with CAN bus are designed using ARM as controller. Digital PWM generator of ARM enhances the static properties and dynamic response ability.μC/OS-Ⅱ, an embedded realtime multi-task operating system, can improve the response ability against various welding signals and software reliability of arc welding inverter and wire feeder. All the contents of the welding process will be divided into different tasks with priority level. The most important task, the higher priority level. To avoid simultaneous-sharing on the shared resources, some semaphores are introduced in to ensure the smooth performance of the arc welding power supply. An important task transfers data processed to other not important task via message boxes to improve the data processing speed.The CAN bus is a communication media via it welding equipment share information. A welding communication protocol for welding equipment information interaction is developed.The local high speed bus between master and slaver arc welding inverter is designed in tandem arc pulsed MIG welding system using full-duplex RS-422 bus. A complete communication protocol is defined.The application of fuzzy logic control technology in double wire welding is researched. Using peak voltage error and error rate as input, pulse valley time as output, fuzzy logic controller controls arc voltage to keep the length of arc stable. Continuous detecting of the wire feeding speed, three parameters of PID controller are adjusted online according to error and erroe rate. The wire feeder has fast response ability and constant wire feeding speed.A distributed control system of tandem arc pulsed MIG high speed welding is designed and a lot of testing are done based on it. The communication between welding equipments can work well and they can closely work together to complete automated welding process. The cooperative control between master and slaver welding power sources works well. The relationship of pulse phases of master and slaver welding currents comply with the design requirements. The arc welding power sources have excellent static and dynamic characteristics. The arc length keeps stable during welding process. The system has high welding speed and high efficiency.更多还原