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以外加横向交变磁场作用下的等离子体弧为研究对象,建立了等离子体弧摆动幅度和热流密度分布的数学模型.对横向交变磁约束下的等离子体弧射流特性进行理论研究,并分析工艺参数和励磁强度对横向交变磁约束等离子体弧形态和特性的影响规律.结果表明,横向交变磁场可有效控制等离子体弧形态和位置,等离子体弧在横向交变磁场作用下,分布范围增大、热流密度梯度减小.其摆动幅度随磁场强度的增加而增大,但过高的磁场强度会使等离子体弧变得不稳定;相同励磁强度下,气流量和弧电流越小、喷嘴到工件的距离越大,则摆动幅度越大;而工件表面的等离子体弧热流密度分布随励磁强度的增强趋于平坦化;相同励磁条件下,热流密度峰值随气体流量和弧电流的增大而增大、随喷嘴到工件距离的增大而减小. 相似文献
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The shape of arc plasma in gas-shielded arc welding is an important factor for the quality and efficiency of the welding. The arc plasma changes its shape by an external magnetic field because the arc is a flow of electricity and is subjected to the electromagnetic force. In this study, we examined the control of arc plasma by a cusp-type magnetic field. The field produces a high and low magnetic area alternatively, and changes the cross-section of the arc plasma from a circular to an elliptical shape. The previous study using solenoid coils to produce a cusp-type magnetic field reported that magnetized arc plasma provided deeper penetration. However, the solenoid device developed for the cusp magnetic field was too large in comparison with the size of the welding torch used for production welding. Therefore, this study investigated the magnetic control of arc plasma with permanent magnets that have recently become smaller in size and higher in intensity. Theoretical analysis model was constructed to determine the optimum arrangement of the magnets. This analysis requires a three-dimensional numerical model because the temperature-, velocity-, and electromagnetic fields of arc plasma change three-dimensionally by the additional magnetic field. It was analytically and experimentally shown in TIG arc welding that the arc shape could be elliptical cross-section even using the permanent magnets. Furthermore, our analysis showed that the effective magnetization direction of magnets was vertical, and this result was confirmed experimentally. As a result, we obtained the good bead appearance in the high-speed welding with this magnetic control. 相似文献
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Aimed at plasma arc welding, a mathematic model was established according to the theory of magnetic fluid dynamics. The model was numerically analyzed by ANSYS software. The temperature, current density and plasma velocity distributions of normal arc had been simulated and compared with those of double arc. The results show that the appearance of double arc has made the temperature of the nozzle rise up to 5 000 K. The appearance of side arc could make the current density of the main arc decrease, and also make the maximal temperature of the arc reduce. 相似文献
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《Science & Technology of Welding & Joining》2013,18(6):443-449
AbstractThe sound emitted during plasma arc cutting is closely related to the cutting conditions including cutting speed, arc current, operating gas flowrate, torch standoff height, nozzle shape, etc., and it therefore contains useful information for the evaluation of the plasma arc cutting process. The present work investigates the characteristics of the sound emitted during plasma arc cutting under various cutting conditions, using fast Fourier transformation and probability statistical analyses. An acoustic model of plasma arc cutting, having two jet sound sources, is proposed to interpret this sound. The sensitive frequency band of the cutting sound and the relationship between the cutting sound and the conditions are then revealed. It is shown that the cutting sound is a random signal readily affected by cutting conditions, and its energy is concentrated in the high frequency field and originates mainly from the mixing region of the first sound source and the mixing and transition regions of the second sound source. Experimental results also suggest the possibility of developing an acoustically based monitor system for this plasma arc process, and of reducing the acoustic exposure level, thereby improving working conditions. 相似文献
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AnewtypeofpilotarcpowersourceusedforA.C.plasmaarcweldingofaluminumalloys¥ZhengBing;WangQilongandLiXia(HarbinInstituteofTechno... 相似文献
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电弧离子镀技术已经成为镀膜技术中不可或缺的技术之一,并在金属、装饰、硬质耐磨等领域被广泛研究和应用。膜层技术的研究应用促使对电弧源技术的研究主要集中在长寿命、高可靠性和大颗粒抑制这几方面,且后者的开展必须建立在前者的基础上。大颗粒抑制的关键在于减少弧斑在靶面的驻留时间,可通过巧妙的永磁或电磁设计来实现具有较强横向磁场分量的靶面,但当磁场强度增大时,必须综合考虑纵向磁场和横向磁场的比例关系,考虑靶材本身的特点。另一种抑制大颗粒的方法是脉冲电弧技术,脉冲电弧源引弧频繁,在结构设计上和恒流电弧源有很大的区别,瞬时电流能达到数千、甚至一万安培以上,能够获得很高的沉积速率,同时阳极的设计使等离子体形成定向喷射,过滤掉大部分大颗粒。 相似文献
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利用设计的轴向磁场产生装置,采用理论与试验相结合的思路,将其作用于非熔化极焊接过程,包括等离子焊接和钨极氩弧焊(TIG)两种焊接方法.利用高速摄像装置观察电弧形态变化,获得并对比两种电弧的变化情况.结果表明,由于等离子电弧本身组成的特殊性,导致其与TIG电弧在同样磁场作用下发生变化的程度不同.然后做出运动受力分析,建立了轴向磁场下的粒子运动模型,由于粒子轴向运动速度的差异性,导致轴向磁场下带电粒子的运动阶段的不同,给出了两者在磁场下不同变化的原因. 相似文献
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对双丝间接电弧在自身磁场及外加磁场变化的情况下,电弧形态随磁感应强度值的变化规律进行了研究.自身磁场变化通过改变两焊丝夹角角度实现,外加磁场由励磁线圈产生,对间接电弧施加横向及纵向磁场,磁场强度利用特斯拉计测出,并借助高速摄像系统对磁场变化时的电弧形态进行拍摄.研究表明,通过改变两焊丝夹角及施加横向磁场的方式,可使两焊丝所夹区域内外磁场强度之差变大,使得电磁力的外扩作用增大,电弧变细长;施加纵向磁场时,电弧在与两焊丝垂直的平面内发生偏转,其偏转程度随纵向磁场强度增加而增加. 相似文献
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交变纵向磁场作用下MIG焊电弧行为研究 总被引:1,自引:0,他引:1
为了研究交变纵向磁场作用下MIG焊接电弧的物理特性,提高焊接质量,分析了交变纵向磁场作用下电弧带电粒子的受力情况和运动状态,并利用高速摄像手段研究了交变纵向磁场对电弧形态的影响。结果表明,无外加交变纵向磁场时,自由电弧稳定燃烧,电弧轴线与焊丝轴线相重合;当加入交变纵向磁场时,电弧围绕焊丝轴线做逆时针和顺时针交替变化的旋转运动,电弧轴线偏离焊丝轴线;随着励磁电流的增加,电弧的旋转半径增大,电弧偏离焊丝轴线的角度增大,电弧烁亮区域面积减小;当励磁电流为30 A时,电弧的最大偏转角度为45°,此时电弧燃烧变得不稳定,甚至息弧,焊接过程不稳定。 相似文献
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根据流体的质量、动量、能量守恒方程,建立了穿孔等离子弧焊接过程中的等离子电弧三维数学模型,用磁矢量法求解磁场问题.模型包括了一部分喷嘴和钨阴极,小孔也被包含进模型中.利用ANSYS有限元分析软件求解模型,得到等离子电弧的温度分布,以研究等离子弧焊中电弧反翘现象.结果表明,等离子电弧反翘随小孔尺寸的增大而减弱,电弧尾焰随小孔尺寸的增大而增强;而适当的增加焊接速度以使小孔轴线与电弧轴线之间形成一定的偏差是形成等离子电弧反翘现象的必要条件;焊接电流主要是通过改变小孔尺寸而对电弧反翘产生影响. 相似文献
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在镍基堆焊合金等离子弧堆焊过程中引入横向交流脉冲磁场,研究了横向交流脉冲磁场频率对等离子弧堆焊层金属组织及性能的影响,并利用光学金相、x射线衍射、显微硬度和湿砂橡胶轮磨损试验等方法,系统分析了不同脉冲磁场频率作用下堆焊试样的硬度、耐磨性及组织.结果表明,外加横向交流脉冲磁场可以有效改善堆焊层金属的结晶形态,细化晶粒,在适当的脉冲磁场频率作用下,可以获得最佳的电磁搅拌效果,增加堆焊层金属中硬质相的数量,控制硬质相的生长方向,提高等离子弧堆焊层的硬度和耐磨性.Abstract: The nickel-base alloy was deposited on the low carbon steel by plasma arc surfacing with transverse magnetic field. The influence of transverse alternative pulsed magnetic field frequency on microstrueture and properties of plasma arc surfacing layer was researched. The hardness, wear resistance and micmstructure of surfacing layer at different pulsed magnetic field currents were systematically analyzed by optical electronic microscope, wear test and microscopic hardness test. The results indicated that the transverse alternative pulsed magnetic field can effectively improve the crystal shape in plasma arc surfacing layer and refine crystal grain. With the proper pulsed magnetic field frequency, the optimum effete of electromagnetic stirring can be obtained, the amount of hardening phase in overlay deposit is increased, the growth direction of hardening phase can be controlled and the hardness and wear resistance of the surfacing overlay are improved. 相似文献