共查询到18条相似文献,搜索用时 60 毫秒
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反极性弱等离子弧增材制造具有制造周期短、制造成本低、工件可靠性强等特点,具有广阔的应用前景。介绍了3种反极性等离子弧丝材熔积增材制造方法的基本原理和应用现状,并分别从控制系统、焊接设备、焊接材料等3大方面综合论述了等离子弧增材制造的发展现状和存在的问题,分析了反极性等离子弧增材制造的发展方向。 相似文献
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以变极性等离子电弧稳定性机理及其控制方法为研究对象,自行研制了80C196KC单片机为控制核心,主电路为双逆变型电路拓扑结构的VPPA1型变极性等离子焊接电源.重点分析小电流过零再引燃机理及其在大规范焊接条件下变极性等离子弧焊接系统及其电弧的稳定性.分别提出了在小电流焊接时通过程序设定方法将变极性等离子电弧由正极性变反极性之前提高过零电流,而大规范焊接条件下则控制过零电流的新观点,对科学认识变极性等离子电弧特性及其焊接过程控制有重要的指导意义. 相似文献
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采用光谱方法对水蒸气等离子弧的组成和温度进行了诊断,诊断结果表明,水蒸气等离子弧主要由氢原子、氢离子、氧原子、氧离子和白南电子组成;水蒸气等离子弧具有高温高焓特性,并具有强氧化性。通过光谱法对水、水 乙醇及水 丙酮等不同介质的水蒸气等离子弧温度进行了测量,结果表明,纯水介质的水蒸气等离子弧温度最高,水 乙醇介质电弧温度最低;随着乙醇或丙酮浓度的增加,电弧温度下降。对不同介质的水蒸气等离子弧的切割和焊接性能进行了试验研究,试验结果表明,浓度为20%~30%的乙醇或丙酮水蒸气等离子弧具有较好的切割性能;但是水蒸气等离子弧的焊接性能还不能令人满意。 相似文献
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A double invert variable polarity plasma arc (VPPA) power source based on 16-bit MCU applied for aluminum alloys was developed. Mechanics, electrical and the produced heat mechanism of VPPAW arc were tested and analyzed. Results indicate that during the VPPA welding procedure of aluminum alloy, the arc of electrode negative (EN) has more effect on force, whereas the arc of electrode positive ( EP ) has more effect on heat. It should be noted that keeping the balance of the force and heat is the critical element of VPPAW. This power source had been successfully used to weld aluminum alloy with a 15 mm thickness in vertical welding. The conclusions are applicable to the variable polarity plasma arc welding technique used in the aerospace industry. 相似文献
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变极性等离子弧焊的优点在于能够灵活调节特征工艺参数如电流频率、正负半波电流幅值及导通时间比,以满足铝合金焊接时的阴极清理和形成穿孔焊。介绍了国内外在实现变极性电流波形、电弧稳定性、阴极清理机理、小孔信号检测等方面的研究现状。指出保证前后级同步是双逆变电路形式的技术关键,双通道形式可克服主、维弧干涉并降低钨电极烧损。溅射、电介质击穿及瞬时熔化和蒸发是目前解释阴极清理机理的主要理论,重要的是工艺参数对清理的影响规律。近年来又出现了几种新的小孔检测方法,而正面检测及多传感信息融合仍是其主要发展方向。 相似文献
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分析了铝合金变极性等离子弧穿孔立焊工艺特点,提出了通过对焊接参数的精确控制,实现变断面铝合金变极性等离子弧穿孔立焊工艺的方法,并将焊接电流、离子气流量和焊接速度确定为变断面铝合金变极性等离子弧穿孔立焊过程的被调节参数.保持穿孔熔池上"热"和"力"的动态平衡是调节焊接参数的根本依据,是实现变断面试件自动焊接的关键所在.采用单片机为核心的控制器对焊接参数进行实时调节,动态保持穿孔熔池上热和力平衡,实现了变断面铝合金变极性等离子弧穿孔立焊工艺. 相似文献
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利用U形压力计测试了不同工艺参数条件下的变极性等离子焊接的电弧压力,利用正交试验测试了不同正极性电流、反极性电流、正反极性时间比和等离子气流量四种参数条件下的电弧压力.结果表明,电弧压力随着这些因素的增加而增加,而四种因素对电弧压力影响的大小依次为:等离子气流量>正极性电流>正反极性时间比>反极性电流.分析原因,等离子气流量是通过冷却压缩提高电弧压力,压缩了电弧尺寸,而焊接电流则通过电磁压缩,但也提高了电弧半径.由于正反极性阶段电弧压力的差异较为明显.因此正反极性时间比对电弧压力也有显著的作用.Abstract: VPPA pressure was measured at different welding parameters by U-tube barometer method. The effects of different welding conditions on arc force, including straight polarity current, reverse polarity current, time ratio, plasma gas flow rate were analyzed by the orthogonal experiment. The results indicates that VPPA pressure increased with these four parameters, and the influences of the welding parameters are in order of plasma gas flow rate, straight polarity current, time ratio, and reverse polarity current. Then the mechanisms were discussed. The plasma gas can cool and compress the arc column and compress the arc radius, which increases the VPPA pressure; while the welding current increases the arc radius by electromagnetic compression, which enhances the VPPA pressure. Moreover, due to the great difference of VPPA pressure between straight polarity phase and reverse polarity phase, time ratio is also one of key factors to VPPA pressure. 相似文献
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研发了一种单电源双脉冲混合调制VPPA(variable polarity plasma arc,VPPA)焊接系统,在典型VPPA焊接基础上加入高低频调制脉冲,可输出1~5 kHz高频脉冲,1~2 Hz低频脉冲及高低频混合脉冲. 以3003铝合金为试验对象,采用脉冲VPPA焊接方法,对其进行焊接试验,并通过焊接接头拉伸性能测试、显微相组织分析及断口扫描电镜等手段对铝合金的焊接质量和接头性能进行了分析. 结果表明,由于高低频混合脉冲电流的周期性变化,对熔池产生搅拌、冲击作用,从而提高了焊接接头抗拉强度,细化焊缝晶粒组织,断口韧窝趋于均匀且密度增加,提高了铝合金焊缝质量. 相似文献
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Variable polarity plasma arc welding (VPPAW) is one of the most excellent processes used for welding aluminum alloys recently. It combines the advantages of variable polarity welding and plasma are welding, and can achieve the most rational heat distribution and cathodic cleaning. With the VPPAW equipment developed by authors, the cathodic cleaning regularity that is one of the most important problems in VPPAW is investigated in this paper. The results will be helpful in realizing the real cleaning mechanism. 相似文献