Inverter power supply system for high-power twin-wire pulsed GMAW

A type of novel inverter power supply system for high-power twin-wire pulsed gas metal arc welding (GMAW) is presented mainly for dealing with the disadvantages of the conventional power supply for twin-wire pulsed GMAW of which the output power is generally difficult to increase due to limitations of the power of semiconductors and the power density of magnetic devices.In the power supplies for the master and slave arcs,the digital signal processor (DSP) TMS320F28335 is used to form the DSP-based synergic control system for parallel high-power pulsed GMA W,which achieves high-power output of two parallel inverters controlled by a single DSP;master-slave communication is achieved by using e controller area network (eCAN)module of DSP,thus realizing anti-phase pulse output of high-power twin-wire pulsed GMA W and reducing the interference between twin arcs.The experiment results demonstrate that the designed inverter power supply system for high-power twin-wire pulsed GMAW can bring about high-power efficiency of welding,stable welding process and proper formation of welds.     

Study on fuzzy control IGBT inverter arc welding power source for robot

Arc welding robot is playing more and more important roles in modern welding manufacturing, but now available welding power sources seldom satisfy with robot system requirements. In this paper, study on fuzzy control IGBT inverter arc welding power source for robot is developed to bring robotic advantages into full play. Firstly, fast response 500A IGBT inverter arc welding rectifier is developed. Secondly, fuzzy control system, which features multi-functions, fast response and wide using range, is developed and reliable measures for preventing interference are designed. Finally, technological experiments for carbon steel are made. The welding experimental results show that the goal of design is attained.     

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.     

Digital arc welding power supply based on real-time operating system

A digital arc welding power supply was designed with the advanced reduced instruction set computer machine （ARM） and embedded real-time multi-task operating system micro C/OS- Ⅱ. The ARM, with its powerful calculating speed and complete peripheral equipments, is very suitable to work as the controller of the digital power supply. The micro C/OS- Ⅱ transplanted in ARM, helps to improve the respondent speed against various welding signals, as well as the reliability of the controlling software. The welding process consists of nine tasks. The tasks of great significance on reliability of the welder, for example, the A/D conversion of current and voltage, enjoy top priority. To avoid simultaneous-sharing on A/D converter and LCD module, two semaphores are introduced in to ensure the smooth performance of the welding power supply. Proven by experiments ,the ARM and the micro C/OS- Ⅱ can greatly improve both the respondent speed and the reliability of the digital welder.     

Effect of side transmission of power ultrasonic on structure of AZ81 magnesium alloy

In order to promote the application of power ultrasonic in metallurgic industry, ultrasonic vibration is introduced from the side of AZ81 ingot by adopting the automatic-attracting amplitude transformer horn which has independently been designed and produced, and the effect of the side transmission of ultrasonic on the solidification structure of metal is investigated. The results show that under this experimental condition, power ultrasonic can greatly improve the solidification structure of AZ81 magnesium alloy. Compared with the traditional modification methods in which inoculants are added into melt, power ultrasonic has a better performance. The present research gives us a new way for the application of ultrasonic refinement technique.     

Effect of ultrasonic melt treatment on degassing of Mg-6Zn-1Ca alloy

The effect of ultrasonic power and treatment time on degassing of Mg-6Zn-1Ca alloy was studied in this paper. The degassing effect was characterized by measuring densities of ingots. The results show that proper ultrasonic treatment can remove hydrogen from the melt of the Mg-6Zn-1Ca alloy. The ultrasonic degassing effect is closely related to the ultrasonic power density and treatment time. The degassing efficiency increases with an increase in ultrasonic power density when the melt is treated at 690 °C for 120 s, reaching its highest value at 1.2 W·cm-3. When the power density is 1.2 W·cm-3, with an increase in ultrasonic treatment time, the degassing efficiency increases at first, reaches its peak value at 120 s, then decreases as the ultrasonic treatment is further prolonged. In this experiment, the optimum degassing effect with an efficiency of 67.5 % is obtained by ultrasonic treatment with the power density of 1.2 W·cm-3 for 120 s. The maximum density of ingot can be increased from 1.8069 g·cm-3 to 1.8146 g·cm-3(increased by 0.43%).     

Effect of Ultrasound on Heterogeneous Nucleation in TIG Welding of Al–Li Alloy

The effect of ultrasound on heterogeneous nucleation in a tungsten inert gas(TIG) weld pool of 2195 Al–Li alloy has been investigated by a series of experiments. An ultrasonic vibration was imposed on the surface of base material before turning off the welding arc during the TIG welding implemented at a fixed point. The results suggest that ultrasound could promote heterogeneous nucleation in the TIG weld pool of 2195 Al–Li alloy. The grain around the fusion zone is changed from a column grain to an equiaxed grain after applying the ultrasonic treatment. To study the influencing mechanism of ultrasound on heterogeneous nucleation, further investigations were implemented where the welding arc was turned off after turning off the ultrasonic power. The results show that the equiaxed grain around the fusion zone disappeared gradually with an increase in heat input after turning off the ultrasonic power. It suggests that ultrasound could promote the heterogeneous nucleation particle to nucleate in advance before turning off the welding arc and the crystal nucleus could again be melted with an increase in heat input after turning off the ultrasonic power. Moreover, the effects of the welding current and ultrasonic amplitude on heterogeneous nucleation in the weld pool of 2195 Al–Li alloy were also investigated. Possible influencing mechanism of the welding current and ultrasonic amplitude on heterogeneous nucleation was discussed.     

A time-dependent measuring system for welding deformation

In this paper the establishment and application of a time-dependem measuring system for welding deformation are presented which is established with high quality sensors shielded from strong welding interferetwe. By using this system,vertical and horizontal displacements of the high temperature area are surveyed at the same time. And this system is also used for monitoring and controlling the deformation of real welded suttctures.     

Identification of acoustic emission signal in aluminum alloys spot welding based on fractal theory

The acoustic emission signal of aluminum alloys spot welding includes the information of forming nugget and is one of the important parameters in the quality control. Due to the nonlinearity of the signals, classic Euclidean geometry can not be applied to depict exactly. The fractal theory is implemented to quantitatively describe the characteristics of the acoustic emission signals. The experiment and calculation results show that the box counting dimension of acoustic emission signal, between 1 and 2, are distinctive from different nugget areas in AC spot welding. It is proved that box counting dimension is an effective characteristic parameter to evaluate spot welding quality. In addition, fractal theory can also be applied in other spot welding parameters, such as voltage, current, electrode force and so on, for the purpose of recognizing the spot welding quality.     

A research of arc welding inverter with high stable precision

This paper mainly introduces an output control method with high stable precision of a large power IGBT arc welding inverter.Experiments indicate that this kind of control mode can effectively improve the static and dynamic characteristics and stability of power supply system.And it can decrease the spatters in the welding process apparently.This power supply is especially suitable to automatic robot welding assembly line.It will be the developing direction of robot welding supply in the future.     

超声金属焊接双法兰结构声学系统设计

针对超声金属焊接声学系统需承载径向分力,而传统单法兰支承结构难以同时满足超声传递和结构刚度双重要求的问题,基于Ansys数值仿真与单因素实验相结合的方法,开展了超声金属焊接双法兰结构声学系统优化设计研究。首先,对声学系统进行分析,提出了一种声学系统双法兰支承方案;其次,进行法兰厚度尺寸对超声传递效率和支承结构刚度的影响规律研究;最后,通过实验对所设计的声学系统进行性能测试。结果表明:振动系统振幅放大倍数大于2.5,在满足焊接振幅要求的前提下,结构刚度大幅提高。通过仿真分析和实验,验证了双法兰结构的有效性,为超声金属焊接声学组件设计提供了新思路。     

基于超声跨态处理的焊接热循环试验

设计了基于超声跨态处理条件下的激光焊接热循环测试试验,分析超声振动对焊接过程的热影响表明,功率超声对焊接过程的热影响主要集中在声学效应、传热学效应及机械搅拌作用三个方面;研究了不同超声振动功率对焊接最高温度、加热速度、高温停留时间以及冷却时间等特征参数的影响规律,并结合功率超声对焊接过程的热影响分析对其本质原因进行了深入研究.结果表明,随超声功率的增加,焊接最高温度和高温停留时间均呈先降低后升高最后再降低的趋势,并且焊接最高温度在超声振动功率为1 200 W左右达到最大值;升温时间呈持续增加的趋势,但不同超声功率所对应的增加速率各不相同,而冷却时间则保持减小趋势.     

锂电池极片超声波金属焊接机的设计

根据锂电池电极焊接工艺要求,提出了一种基于压电陶瓷纵向振动的机械结构形式,设计了一种全数字化控制的超声波金属焊接机电源系统.该电源系统采用移相PWM数字振幅控制、振幅阶梯输出、可编程的缓启动,自动焊头频率搜索及自动频率跟踪等技术.实际使用证明,该机能快速实现自动频率跟踪、精确振幅控制、完善故障保护.     

基于DSP控制的超声金属焊接电源

为了进一步提高超声金属焊接的可靠性与稳定性,针对现有模拟超声焊接电源频率跟踪性能差、焊接过程振幅不可调的缺陷,文中提出了基于数字信号处理器(DSP)控制的超声电源方案.通过采集压电换能器两端电压、电流相位差,利用增量式PI控制算法实现了焊接过程的频率跟踪;采用脉冲宽度调节的方式实现了焊接过程超声振幅大小的调节.结果表明,采用数字控制的超声电源,实现了焊接过程振幅的连续可调;负载突变时,0.32 ms时间内可以实现频率跟踪过程.     

Input electrical impedance as signature for nondestructive evaluation of weld quality during ultrasonic welding of plastics

As a wide applied joining process of plastics with long history, ultrasonic welding of plastics could be helped by newer technologies in sensing, pattern recognition, etc. to improve production rate and weld quality. This paper introduces a new concept which allows in situ monitoring of an ultrasonic welding process in real time and assessing the resulted weld quality right after the completion of the process. In the method, the input voltage and current of a welding machine are first probed and processed to obtain the input electrical impedance during the whole welding period. Because there are no changes of the dynamic properties of the welding machine and fixtures during the process, the detected waveforms of the real and imaginary part of the impedance directly reflect the thermo-mechanical behavior of the plastic work-pieces at the joining point. By recognizing the patterns of these waveforms, the joining quality could then be properly evaluated. This new concept and the accordingly derived nondestructive evaluation method were investigated experimentally. The results show that the input electrical impedance is an effective signature and that the built system evaluates bonding quality of welds effectively and efficiently.     

CO2焊接逆变电源-电弧系统的仿真

由于短路过渡CO2焊接电弧负载的非线性与时变性的特点，CO2焊接电源-电弧系统的研究与设计有其固有的难点。作者采用在控制领域最具影响的MATLAB软件，在对CO2焊接电弧建模、逆变电源-电弧系统建模的基础上，仿真了波形控制CO2焊接逆变电源-电弧系统的动态过程，并且在模拟示波器上输出了CO2焊接电弧的几个典型参数的动态波形。通过计算机仿真，提出了CO2焊接过程平衡长度的概念，揭示了焊接过程平衡长度的物理过程，CO2焊接过程平衡长度的变化范围必须是大于零、最大值是几毫米(具体值与焊接参数有关)的数量程度。给出了波形控制CO2焊接逆变电源-电弧系统的控制结构，通过仿真可以看出短路过渡CO2焊接逆变电源控制参数对系统的影响规律，辅助优化设计系统。     

Effect of edge preparation on the weldability of plastics in ultrasonic welding

The kinetic mechanism of the formation of welded joints with ‘preferential penetration’ and ‘preferential melting’ in ultrasonic welding of plastics is described. It is shown that the preparation of weld edges in ultrasonic welding of rigid plastics increases the welding speed.     

埋弧焊电弧超声激励及其热动力学效应

为研究电弧超声激励的一般规律和电弧超声的热力学与动力学效应，选择超声频段的高频激励源与常规工频埋弧焊电源进行电磁耦合，在燃弧过程中激励出电弧超声，并对声发射信号进行了频谱分析。采用大弧焊参数并分别施加不同的激励频率进行埋弧焊试验，对焊接试样的熔合区与热影响区形态进行观察，研究熔合区和热影响区在电弧超声影响下的形态变化规律，并据此对电弧超声的热力学和动力学效应进行了初步探讨。     

激光焊接过程多传感器信号调理电路的设计

介绍了一种激光焊接声、光信号采集与信号调理电路的设计原理，并结出了相应的电路图。试验表明：该采集电路能够正确采集激光焊接过程特征信号，并能有教反映焊接过程的变化．可以满足激光焊接过程实时监测的要求。     

智能化逆变弧焊电源控制策略现状及发展趋势

弧焊电源是整个焊接设备的核心,而弧焊电源的发展更决定了焊接领域的发展。其中弧焊电源控制的好坏,直接影响着弧焊电源中各参数的反应速度与效率,因此,弧焊电源的控制设计成为其重要环节。本文介绍了逆变弧焊电源的发展历史,重点论述了智能化逆变弧焊电源控制的现状,介绍了近年来在逆变弧焊电源技术中模糊控制、神经网络控制、视觉采样以及...