脉冲真空电弧离子镀发射特性的测量

通过大量工艺实验,镀制了改变脉冲真空电弧离子源电源参数(主回路电压,脉冲频率)、基片高度以及磁场等工艺参数的样品,选择了一种合适的膜厚测量仪器进行了膜厚分布测量,获得了离子源各种工艺参数对其发射特性影响的曲线.     

脉冲真空电弧离子镀发射特性的测量

通过大量工艺实验,镀制了改变脉冲真空电弧离子源电源参数(主回路电压,脉冲频率)、基片高度以及磁场等工艺参数的样品,选择了一种合适的膜厚测量仪器进行了膜厚分布测量,获得了离子源各种工艺参数对其发射特性影响的曲线.     

脉冲真空电弧离子镀发射特性的测量

通过大量工艺实验 ,镀制了改变脉冲真空电弧离子源电源参数 (主回路电压 ,脉冲频率 )、基片高度以及磁场等工艺参数的样品 ,选择了一种合适的膜厚测量仪器进行了膜厚分布测量 ,获得了离子源各种工艺参数对其发射特性影响的曲线     

Research on narrow-gap GMAW with swing arc system in horizontal position

In this paper, a novel swing arc welding system developed for horizontal narrow gap gas metal arc welding (NG-GMAW) which was used in welding and joining heavy plate structures was designed and attempted. Using this welding system, two sound heavy plate beads, i.e., “multi-layer single-pass” welding and “multi-layer double-pass” welding structures, were obtained through adjusting swing amplitude and frequency. Two different welding structures are both without sagged molten pool and interlayer slags, especially obtaining the complete sidewall penetration. All these welding features ensure the bead with higher tensile properties and hardness than the base metal, respectively. This welding system displays considerable flexibility and convenience and possesses a tremendous advantage in the auto-welding industry.     

The chaotic characteristic of the carbon-monoxide utilization ratio in the blast furnace

In this paper, carbon monoxide utilization ratio (CMUR) is served as a real-time index to evaluate the energy consumption of blast furnace (BF), and the chaotic analysis method is also presented to study the characteristic of CMUR. Firstly, the time series data measured from two representative BFs are adopted as the sample to investigate the characteristics of CMUR. Secondly, the phase space model of CMUR is reconstructed, and two key related parameters of the model are derived as well. Finally, the value of the chaotic attractor's saturated correlative dimensions in the reconstructed phase space of CMUR is obtained. The result shows that the sample time series of these two BFs have chaos property. Furthermore, the development process of CMUR is also proved to be the chaotic process. It provides a solid foundation for us to further study the chaotic predication and control of CMUR, which helps us to better master the variational tendency of CMUR and provides the effective operation guidance for the BF on the spot to reduce the energy consumption in BF.     

电子灭弧器-用于消除交流接触器的触点电弧

在控制三相电动机起动和停止时，交流接触器触点间通常会产生很强的飞弧。对交流接触器的触头造成损害。电子灭弧器从根本上消除了产生飞弧的原因而彻底灭弧，保护了交流接触器和设备的使用安全。     

Heat input in full penetration welds in gas metal arc welding (GMAW)

Weld bead characteristics are metallurgically controlled by heat input, which depends on the welding parameters. However, for numerous welding specialists, an accurate measurement of the current, voltage, and welding speed is enough for preventing unambiguous process specifications. But a comprehensive knowledge of the effect of others parameters, such as plate thickness and the type of pass to be performed (full penetration, root pass, or filler pass), is also required if a less conservative welding procedure is aimed. The goal of the present paper is to increase the ability to control the quality of the welding processes used in production by considering the effect of heat losses through the back side of the weld by radiation for full penetration welding, when developing welding procedure specifications. It is concluded that the thermal efficiency factor and, consequently, the heat input need to be differentiated in the welding specifications for full penetration welding.     

Impacts of external longitudinal magnetic field on arc plasma and droplet during short-circuit GMAW

In gas metal arc welding, electromagnetic force, plasma stream force, gravity, and surface tension are the most important factors that affect metal transfer and spatter generation rate. In this paper, different kinds of external electromagnetic fields were introduced to gas metal arc welding (GMAW). The photos of arc plasma and droplet and electric signals covering welding current and arc voltage were acquired synchronously by an analysis and evaluation system based on LabView for GMAW. It was confirmed that the metal transfer frequency was improved, and spatter generation rate was diminished under controls of external electromagnetic fields. The influencing rules of external electromagnetic fields on electromagnetic force, the gravity, the plasma stream force, and surface tension were studied by three physical models, and the mechanism of external electromagnetic fields was revealed. This paper is for the purpose of discussing these factors and will make a profit for the application of electromagnetic coupling control to short-circuit GMAW.     

TIG焊机中引弧、稳弧脉冲装置的原理与故障排除

结合工作经验和具体机型,分析了直流TIG焊机中引弧脉冲装置的原理和交流TIG焊机中引弧、稳弧脉冲装置的原理,根据具体案例,介绍了此类故障的分析思路和排除方法.     

组合冲头式力脉冲发生器冲击特性研究

为增大力脉冲发生器对冲击脉冲的调节范围,拟采用组合式冲头对传统冲头进行改进。本文使用实验法进行组合冲头的冲击实验,实验证明通过更换组合冲头中高分子材料及其轴向尺寸的方法可达到增大冲击脉冲调节范围的目的。研究表明,在力脉冲发生器中使用组合式冲头可明显增大冲击脉冲峰值和脉宽的调节范围,该方法可作为提高力脉冲发生器性能的一种有效手段。     

Study on arc characteristics and their influences on weld bead geometry in narrow gap GMAW of 5083 Al-alloy

As an efficient process, narrow gap gas metal arc welding (NG-GMAW) was employed to join thick plates of 5083 Al-alloy. In this paper, arc characteristics in NG-GMAW of 5083 Al-alloy and their influence on the weld bead geometry were studied with synchronous acquisition system for various groove types, welding modes, welding current levels, and swing frequencies. The arc profiles were measured and appear to be entirely different compared with that in bead-on-plate GMAW process, meanwhile the arc size changes with varied welding mode, welding current, and arc swing frequency. Arc characteristics highly affect the weld bead geometrical parameters such as bead width, welding penetration, sidewall penetration, and weld surface concavity. Linear regressions were made between the arc characteristics and the weld bead geometrical parameters both in swing and non-swing arc process. It showed that a negative linear correlation exists between welding penetration and arc length, sidewall penetration, and arc warpage, while a positive linear correlation exists between weld surface concavity and arc warpage in non-swing arc process. In contrast, a non-linear correlation exists among them and the variation tendency remains the same in swing arc process.     

New discovery of pulse arc shape of sheet tungsten electrode

Journal of Mechanical Science and Technology - The synergistic effect of sheet tungsten electrode and pulse current can further reduce the heat input, effectively regulate the arc plasma jet...     

Effect of pulse frequency on microstructure and properties of Ti-6Al-4V by ultrahigh-frequency pulse gas tungsten arc welding

An experimental program of welding a titanium alloy, Ti-6Al-4V, was carried out using ultrahigh-frequency pulse gas tungsten arc welding (UHF-GTAW). The characteristics of the welds were investigated, such as the defection, microstructure, and mechanical properties. The experimental results show that the high pulse frequency reduces the heat input from the UHF-GTAW process, while gaining one-side welding with backing as a precondition. Basketweave and long acicular α′ martensite only existed in some areas of the FZ (fusion zone) with both low uniformity and distribution density (8.4 %) as a result of conventional GTAW processes. With a pulsed current, basketweave and short acicular α′ martensite were distributed in the FZ evenly. Short acicular α′ martensite could be detected within the parallel long acicular α′ martensite in the CGR when f?>?30 kHz. Plastic weld joints were characterized by both the elongation, A, and the percentage of the area reduction, Z, and were optimized with a high pulse frequency. Ideal mechanical properties of the joints were achieved with an A of 68 % and a Z of 150 % with f?=?30 kHz. The integrated effects of the pulse frequency and the heat input are the key factors for determining the microstructure morphology and the mechanical properties.     

System identification of controlled pulse keyhole plasma arc welding process

The development of closed-loop control systems is one of the most effective ways to improve the stability of the keyhole status during keyhole plasma arc welding (K-PAW). Due to the disadvantages of the one-pulse-one-keyhole technology based on the conventional square current waveform, the controlled pulse welding current waveform is newly applied to control the keyhole open and close periodically. In order to realize the real-time control on the keyhole behavior with this advanced current waveform, welding experiments and system identification are conducted based on the classical control theory. One complete welding cycle can be divided into 3 periods. The keyhole establishing time is the most important time variable, which determines the keyhole behavior and welding process stability. At the same time, the averaged efflux plasma arc voltage during one pulse cycle can reflect the real keyhole dimension and status in a real-time manner. Therefore, two single-input-single-output (SISO) systems are proposed, in which keyhole establishing time and keyhole average dimension are taken as the system controlled variables respectively. Welding experiments are designed with the peak current varying randomly. Experiments show that the keyhole establishing time changes in an opposite direction to the varied peak current, and the averaged efflux plasma arc voltage varies with the same trend as the peak current. Based on the least squares technique and F test of classical system identification, second order difference equation for keyhole establishing time/peak current system and first order difference equation for keyhole average dimension/peak current system are obtained. It is proved that the calculated data by the two mathematical expressions are well matched with the measured data. The proposed research provides mathematical expressions and theoretical analysis to develop closed-loop systems for the controlled pulse K-PAW.     

The effect of a hot-wire in the tandem GMAW process ascertained by developing a multiphysics simulation model

Journal of Mechanical Science and Technology - Physical phenomena such as arc interference, deflection in droplet transfer, and bulging in weld pool are observed in the tandem gas metal arc welding...     

CO2气体保护焊在汽车焊接中的应用

CO2气体保护焊具有高效、节能、焊接变形小、焊缝成形美观等优点,且随着国产CO2气体保护焊机和焊丝开发应用,只要合理使用CO2气体保护焊,其在汽车工业中有很大的使用价值。     

Estimation and control of droplet size and frequency in projected spray mode of a gas metal arc welding (GMAW) process

New estimators are designed based on the modified force balance model to estimate the detaching droplet size, detached droplet size, and mean value of droplet detachment frequency in a gas metal arc welding process. The proper droplet size for the process to be in the projected spray transfer mode is determined based on the modified force balance model and the designed estimators. Finally, the droplet size and the melting rate are controlled using two proportional-integral (PI) controllers to achieve high weld quality by retaining the transfer mode and generating appropriate signals as inputs of the weld geometry control loop.