弧焊电源的负载持续率及其计算方法

焊接电源工作时会发热,温升过高会使绝缘损坏而烧毁。温升一方面与焊接电源提供的焊接电流大小有关,同时也与焊接电源使用的状态有关：同样焊接电流下,长时间连续焊接时温升高,焊一会、停一会温升低。     

国内外钢轨闪光焊机电源技术现状与发展

分析了国内外各种钢轨闪光焊电源的系统构成、用途;详细说明了交直流钢轨闪光焊电源系统的发展动态;分析了钢轨闪光焊机中焊接负荷过重、偏相引起的焊接电压闪变、焊接电流不稳定、系统功率因数cosφ很低、供电系统发热超载严重的形成机理以及对闪光焊接质量的影响;指出了解决上述问题的可能途径和优选方案;展望了未来钢轨闪光焊电源向直流化、高频化、数字化方向发展.     

苏州三光推出最新快走丝控制系统

苏州三光科技有限公司推出一款最新的EKDK快走丝线切割机控制系统。该控制系统的脉冲电源改变了常规电源系统依靠限流电阻来限流、大量的能量消耗在限流电阻上的电路，根据过山车力学原理，研制了一种全新的电加工电源电路。经过大量的切割试验，BKDK控制系统电加工电源具有以下特点：①低的电能消耗，与同类产品相比电源节能80％以上，而且控制柜不发热；②高的加工速度，加工电流为5．3A时，最快加工速度140mm^2／min；     

焊机的正确使用方法(四)——阻焊机的使用须知

一、设备 1.电源变压器阻焊机的负载持续率较低,在一个单位周期的短时间内承受大电流,因此在选择电源变压器时要考虑两点:(1)从发热方面考虑要具有足够的容量;(2)通电时电压降不能太大。     

Cu/Ni异种细直径金属丝自动钎焊设备研制

以发热电缆线芯制造为研究对象,采用深熔钎焊方法,研制出发热电缆线芯自动钎焊设备,实现不等径的Cu/Ni异种金属丝自动对接钎焊。阐述了发热电缆线芯自动钎焊设备的总体结构及功能;分析了发热电缆线芯自动钎焊设备的电源系统,其主电路采用单相交流调压结构;采用PLC控制器进行系统多轴协调控制。经实际应用,并通过拉伸试验机和扫描电镜对焊接接头的力学性能和微观组织进行了研究分析。结果表明,发热电缆线芯自动钎焊设备运行稳定可靠,较手动钎焊,其工作效率和接头质量明显提高。     

焊接设备——熔焊设备

20061180 弧焊电源的焊接电流、负载持续率和发热试验；20061181 基于小波分析仪的CO2焊机波形分析；20061182 PCH-110谐振焊接电源；20061183 用于长焊缝的埋弧焊装置；20061184 PAW2000管道全位置自动焊机；20061185 用于伺服焊钳自动化的模块系统；     

热管散热器在逆变弧焊电源中的应用

逆变弧焊电源不仅高效节能，而且质量轻，体积小，动态特性和弧焊性能好。其中的二极管，ＩＧＢＴ等发热器件采用热管散热器后，能进一步加大焊接电流提高了整机的综合性能，是现代焊机的发展方向之一。     

冷却风扇改装

冷却风扇改装我厂的天津仪表机床厂ＤＫ７７４０型线切割机床，工作比较稳定，只是功效控制柜和高频脉冲电源柜开机不长时间机柜箱体发热，而其冷却风扇均工作，只好将柜门打开散热，经仔细观察，原来功放控制柜的风扇据柜的上端，向下吹风，这样，功放元件发热的热空气，...     

晶体管式电阻点焊电源及其复合模式控制研究

为解决精密电阻焊过程中接触电阻变化范围大且难以预估,并由此产生焊接飞溅、虚焊等焊接质量不良的问题,设计了一种晶体管式电阻点焊电源及复合控制模式。主要介绍了晶体管式电源的主电路结构、工作原理、以dsPIC33FJ64GS610为核心的控制系统及复合控制方法。电源输出采用MOSFET开关100 kHz斩波控制,最大输出电流4 000 A,能够对电压、电流反馈快速响应。复合控制模式将恒压控制与恒流控制相结合,焊接初期采用电压反馈控制适应接触电阻的变化,在短时间内降低电阻焊过程中的不确定因素,后期利用恒流模式焊接,保证焊点发热。实验结果表明,针对初期接触电阻差异大的工件结构,复合控制模式能够有效提高其焊接稳定性。     

两种保护直流电器的节电驱动电源

在工厂常用的直流继电器、接触器、电磁铁与电磁阀中，维持铁芯吸合的线圈电流仅为吸合动作电流的20～25％左右。而一般在控制线路中，其线圈两端电压不变，则维持电流相当大而又根本没有必要，这样不仅线圈发热厉害，而且控制电源和驱动元件功耗增大，因而除对元器件选用要求严格外，又浪费了电能。尤其对有些直流电器线圈通电要求在一定的负载持续率之内，而使用场合又必须通电时间较长，则上述问题就显得更为突出。针对上述问题，现设计了两种性能优良的节电直流驱动电源。图1是小功率直流电器驱动电源，图2是大功率直流电磁阀类电器驱动…     

Free forming of locally heated specimens

A novel manufacturing method is investigated, in which a steep temperature gradient within the workpiece is induced to facilitate material flow locally. By this method, complex shapes can be formed without complicated dies. The feasibility of the idea is analyzed experimentally and numerically. Local heating is realized either by means of induction or laser heating. Experiments using materials 16MnCr5, X5CrNi18/9, and Ti6Al4V have been conducted under various process conditions. These experiments have also been modeled by finite element method (FEM) validating the analysis procedure. Electromagnetic models are used to analyze the heat generation pattern on the workpiece by induction. It is found that the most important process parameters are the thermal diffusivity and the temperature sensitivity of the flow curve of the workpiece material. The lower the thermal diffusivity and the higher the temperature sensitivity, the more differentiated local shapes can be formed. For the analyzed geometries, induction heating has been observed to be more effective. Deformation rate and initial workpiece geometry have also a significant effect on the achievable local deformations. Various failure modes such as unintended deformations, damage by fracture, and melting of the workpiece material are described. It is concluded that the new idea of forming local shapes by local heating is a feasible and controllable manufacturing alternative.     

Load relaxation of helical extension springs in transient thermal environments

The load relaxation behavior of small Elgiloy helical extension springs has been evaluated by a combined experimental and modeling approach. Isothermal, continuous heating, and interrupted heating relaxation tests of a specific spring design were conducted. Spring constants also were measured and compared with predictions using common spring formulas. For the constant heating rate relaxation tests, it was found that the springs retained their strength to higher temperatures at higher heating rates. A model, which describes the relaxation behavior, was developed and calibrated with the isothermal load relaxation tests. The model incorporates both time-independent deformation mechanisms, such as thermal expansion and shear modulus changes, as well as time-dependent mechanisms such as primary and steady state creep. The model was shown to accurately predict the load relaxation behavior for the continuous heating tests, as well as for a complex stepwise heating thermal cycle. The model can be used to determine the relaxation behavior for any arbitrary thermal cycle. An extension of the model to other spring designs is discussed.     

钢铁零件在氧化气氛中加热的防护

钢铁零件在空气介质中加热会发生氧化脱碳,不仅造成材料损失,也影响零件的热处理质量。硼砂水溶液、硼酸酒精溶液、氯化物水溶液和QW—F1保护剂均可以有效防止钢铁零件在空气中加热过程中发生氧化脱碳。介绍了这些防护剂的防护原理、主要成分、操作方法和应用实例。     

磁感加热法—节能环保的挤压锭坯加热工艺

介绍德国新开发的用于加热挤压铝合金锭坯的磁感加热系统的工作原理、装置结构及使用中的诸多优点。     

12V240曲轴镦锻感应电加热制度的研究

采用有限元数值模拟技术，分析了１２Ｖ２４０ 机车曲轴坯的感应电加热制度。按照镦锻工艺的要求，提出了改进的加热制度，为实际生产应用提供了依据和参考。     

热成形加热新技术

针对常规连续辊底炉的能耗高、维护成本高的缺点,提出了多层箱式炉的设计方案;针对常规加热方式的奥氏体化时间长、易氧化的缺点,依次研究了直接通电加热、感应加热和直接热传导加热3种新的热冲压加热成形工艺技术。直接通电加热具有加热速度快(可达250 ℃/s）、热效率高、能耗低、氧化少、成形后组织均匀,硬度高的特点,并可用于局部加热及不等温加热处理;通过合理配置和设计感应加热器的组合,可以实现奥氏体化35 s,总加热时间在35 s到60 s之间,加热速率最大可达到200 ℃/s,温度偏差控制在10 ℃之内;直接传导加热方式,在炉时间从传统炉的5~7 min减少到20~40 s,装置占地小,加热速度和加热温度可调范围宽、调节速度快,可满足不同系列要求的热冲压工艺需要。     

大型轴类锻件锻前加热的热透时间研究

利用有限元软件DEFORM-3D,对30Cr1Mo1V钢大型轴类锻件加热过程中温度场的变化规律进行了分析,研究了不同尺寸、形状等因素对热透时间的影响,建立了热透时间的数学模型,为制定锻前加热规范提供了理论依据。     

武钢1580mm生产线降温轧制工艺的实践

针对现行加热温度制度中加热温度过高而造成能耗较高、生产成本较高的压力,武钢热轧总厂三分厂经过充分研究分析,进行了降温轧制实践,部分商品材和供冷轧用带钢的热轧加热温度从1250℃大幅降低至1170℃,使轧线成材率提高约030%,吨钢加热平均能耗下降约0040GJ/t,产生了良好的经济效益和社会效益。     

Use of the implant test and acoustic emission technique to investigate hydrogen‐assisted cracking in the fusion zone of welded HSLA‐80 steel

Summary

Hydrogen‐assisted cracking in the fusion zone (FZ) was studied, using flux‐cored wire (AWS E 70T5 and AWS E 120 T5‐K4) and a CO₂ + 5% H₂ gas mixture to induce high values of diffusible hydrogen in high strength, low alloy steel (HSLA‐80) welds. An acoustic emission measurement system (AEMS) based on a root mean square (RMS) voltmeter was coupled to the implant test apparatus (NF 89–100) to determine energy, amplitude and number of signals. Using optical microscopy and scanning electron microscopy (SEM), it was observed that, in all tests, cracks were initiated in the partially molten zone and propagated in the coarse‐grained region of the heat affected zone (HAZ) when E 70 T5 wire was used and quasi‐cleavage (QC) fracture mode was predominant. When E 120 T5 K.4 wire was used, the cracks were propagated vertically across the FZ and the mixed fracture mode was predominant. A significant relationship between acoustic emission (AE) parameters and fracture modes was found in the cracking mechanism.     

电源频率和功率在透热感应加热中的选择

分析了长轴类零件在感应加热中涡流的分布，从加热效率、温度分布的均匀性及加热速度等方面，讨论了在穿透加热中，感应加热电源频率和功率选择时应考虑的因素和选择的依据。