【作者】 马德；

【导师】 殷树言；

【作者基本信息】 北京工业大学 ， 材料加工工程， 2004， 硕士

【摘要】 摘 要铝合金重量轻、比强度高、抗腐蚀性好，又便于回收再利用，近年来在汽车、高速列车、船舶等行业的应用越来越广泛，因此研究高效优质的铝合金焊接技术有重要意义。双脉冲焊，即低频调制脉冲焊是针对铝合金焊接的一种新工艺方法，已成功应用在奥迪 A8 的铝构架和汽车发动机进气管的焊接中，目前该法在国内还没有得到广泛应用和深入研究，本文结合 MCU+DSP 双机系统，在单脉冲焊稳定焊接的基础上提出铝合金双脉冲焊全数字控制系统设计，同时对双脉冲焊铝工艺进行了研究，获得了美观的焊缝成形和优良的焊接质量。传统的逆变焊机及大多数单片机实现的脉冲焊机，由于其基值、峰值闭环控制共用一片脉宽调制芯片，很难兼顾这两个阶段控制系统的静、动态性能指标。随着数字控制技术的发展，尤其是数字信号处理器(DSP)的广泛应用，为数字化控制提供了物质基础。本文针对脉冲焊控制需要，采用变参数数字 PI 调节，即根据工艺需要设计不同的基值电流、峰值电流控制器参数。对脉冲电流波形控制，实现了对脉冲上升沿和下降沿的分别、独立调节，同时很好保证了基值电流和峰值电流控制期间的稳态精度。弧长控制是焊接过程稳定的核心问题，本文提出一种新的电弧控制思路，即弧长同步脉冲控制法，采用一定的弧长控制算法使在弧长发生变化的当前脉冲周期就得到有效的控制，实现了全电流范围内对弧长的快速稳定调节，取得了良好的工艺效果。对薄板铝焊而言，脉冲电流波形的精确控制，弧长的及时调整、有效控制对防止自动焊回烧、短路等现象的发生，获得稳定的焊接过程很重要。实验证明，本文设计的双脉冲全数字控制系统，不仅获得了一致性好的脉冲电流波形，稳定的焊接过程，无回烧、顶丝现象发生（目前铝自动焊中常发生的现象），而且，良好的弧长控制作用防止了飞溅的发生，同时双脉冲焊铝时产生的熔池搅拌作用有效的减小了气孔发生的几率，细化了晶粒，获得了美观的鱼鳞纹焊缝。另外，本文设计的引弧程序实现了可靠的引弧过程。更多还原

【Abstract】 Abstract Aluminum alloy is of light, high strength, anti-erode and can be recycled. It isimportant to study aluminum alloy welding technique for its wide application in car,high-speed train and ship. Double-pulsed gas metal arc (DPMIG) welding is a newprocess for Aluminum alloy welding, it has been applied aboard because beautiful beadappearance can be got, pore and crack can be avoided to great extent using this methodin aluminum alloy welding. Only several foreign companies master the technique now,no correlative product and study in china. On the base of MCU+DSP technique, Fulldigital control system design of DPMIG is presented on the basis of PMIG design inthis study, and DPMIG process is studied too. One anolog chip is used for pulse current control in most conventional method,which is hard to take account of control system dynamic and static performance inpeak period, base period and arc-igniting period, so it is hard to get ideal pulse currentwaveform control result. The development of digital control technique and DSP’sappearance provide base of matter for studying digital welding power. Compared withconventional pulse current control method, the full digital control system design ispresented for PMIG/PMAG welding inverter in this study. A PI regulator with variableparameters is adopted for flexibly and accurately controlled pulse current-waveform.The experimental results validated pulse current’s rising and falling edge can beadjusted respectively and flexibly, the stable state precision of peak and base current isimproved. Arc-length control is the core of welding process stability. A new arc-lengthsynchronization pulse control method is presented and the higher arc-length adjustmentperformance is achieved within a wide range. For sheet metal aluminum welding,timely adjustment and effective control of arc-length is very important in order to avoidmelt back events in the GMAW mass production in an automated production line. The experimental results validated that the desirable control performance isachieved with the repeatable pulse current waveform, high-speed and stable arc-voltageadjustment. Even if arc length varies with higher frequency and large amplitude in －III－<WP=6>北京工业大学工学硕士学位论文DPMIG, the welding process is very stable. Spatter can be avoided with new arc lengthcontrol design and suitable process parameters. In addition, arc ignition program isdesigned and the stable arc ignition process is achieved.更多还原