电子接头自动装配机整体设计

为提高电子接头装配速度、提高装配质量,本文对电子接头自动装配机进行整体设计。电子通讯接头自动装配机由金属套筒与垫圈装配模块、基体与金属插件装配模块、双组件总装模块构成。金属套筒与垫圈装配模块将垫圈水平放置在金属套筒的底部。基体与金属插件装配模块将金属插件插入到基体,并对金属插件进行定位。双组件总装模块的功能是将套筒、垫圈组件和基体、插件组件进行安装,并把套筒外壁压入基体缺口进行固定,结束电子通讯接头的装配过程。

电子接头装配机金属套与垫圈装配模块气压传动系统设计

为提高电子接头装配速度、提高装配质量,电子接头自动装配机已成为各厂商争相研发的对象。为此,本文以电子接头自动装配机金属套与垫圈装配模块的气压控制系统为研究对象,详细分析了气压传动系统的结构及控制流程。为电子接头自动装配机的研发提供有力的技术支撑。

时效工艺对IC10/GH4169异种高温合金电子束焊接接头性能及组织的影响

采用电子束焊接将IC10与GH4169异种高温合金进行连接,结合显微硬度计、光学显微镜和扫描电镜等分析手段,研究了不同热处理工艺对IC10/GH4169异种高温合金焊接接头硬度及微观组织的影响。结果表明,焊缝由柱状晶及胞状组织构成,焊态焊缝中存在Laves相和NbC两类第二相。时效处理并未对接头宏观形貌产生影响,两侧母材区晶粒也未发生明显粗化。在不同时效工艺下,GH4169母材区及焊缝区显微硬度均发生了显著变化,而IC10母材显微硬度并未发生明显变化。时效处理使得IC10母材区晶界处出现了链状分布的析出相,GH4169母材及焊缝区出现了γ′/γ″相以及δ/η相。凝固过程中的元素富集和偏析使得时效处理后的焊缝区γ′/γ″相的分布不均匀。

TC21钛合金电子束焊接接头超高周疲劳行为研究

采用超声疲劳试验方法（20 k Hz）,研究TC21钛合金电子束焊接接头的超高周疲劳性能与断裂机理。结果表明,TC21钛合金电子束焊接接头的疲劳性能要远低于母材的疲劳性能。在短寿命阶段,电子束焊接接头和母材的疲劳裂纹均在表面萌生;当寿命增大时,两者疲劳裂纹的萌生位置均由表面转向内部,母材的疲劳裂纹主要萌生于内部显微组织,而电子束焊接接头疲劳裂纹主要萌生于内部焊接气孔缺陷。当寿命较长时,疲劳源区会出现＂鱼眼＂形貌特征,源区附近有白色颗粒状细晶区,即细晶区（Fine granular area,FGA）,其应力强度因子在2.90~3.33 MPa·m1/2,与疲劳寿命没有直接关系,可以认为是疲劳裂纹扩展门槛值。此外,基于AKINIWA小裂纹扩展理论,定量分析气孔尺寸与TC21焊接接头疲劳极限、疲劳应力的关系。

GH80A镍合金电子束焊接接头旋转弯曲高周疲劳行为研究

随着镍合金电子束焊接在工业中的大量应用,尤其是在航空发动机和燃气轮机等关键长寿命服役设备中的使用,有必要对镍合金电子束焊接接头的高周疲劳属性和断裂机理进行系统的分析研究。作者利用旋转弯曲高周疲劳试验机进行疲劳试验,获得了母材和焊接接头的应力–寿命(S–N)曲线和疲劳断口,同时利用扫描电镜(scanning electron microscope,SEM)对疲劳断口进行了微观特征分析,确定了母材和焊接接头在不同应力幅下的疲劳裂纹萌生区和扩展区,分析了裂纹萌生区位置与应力幅的关系。最后,利用有限元分析了焊接接头热影响区微裂纹位置与大小对材料疲劳性能的影响。从现有的试验和模拟结果可以得到:1)母材和电子束焊接接头应力–寿命(S–N)曲线分布趋势一致,但焊接接头疲劳强度要低于母材,在靠近107周次时,两者疲劳强度差距最小;2)在高应力幅(低周疲劳寿命阶段),母材和焊接接头的疲劳裂纹均起源于试件表面并且都是多点萌生断裂,焊接接头疲劳断口位置位于焊接熔合区或热影响区;3)在低应力幅(高周疲劳寿命阶段),疲劳裂纹在试件次表面萌生,焊接接头疲劳断口位于热影响区或焊接母材靠近热影响区;4)通过有限元模拟发现微裂纹的存在有利于裂纹的扩展。在拉应力作用下,横向微裂纹更优于纵向微裂纹沿着应力方向进行裂纹扩展;随着微裂纹尺寸增大,微裂纹间更易于相互贯通,形成更长的裂纹,从而降低了材料的疲劳性能。综上可知,电子束焊接仅仅影响材料的疲劳强度。疲劳断裂机理和母材一致都为穿晶解理断裂,疲劳裂纹萌生区域位置也和母材一样都受应力幅的直接影响。

TA12改进型钛合金电子束焊接头性能分析

采用真空电子束焊对TA12合金进行了焊接,试样表面成型性良好。通过光学显微镜、拉伸和疲劳试验等方法,对获得焊接接头的组织和机械性能进行了研究。结果表明:真空电子束焊焊接TA12改进型合金,焊缝区以马氏体为主,焊接接头有很好的机械性能,达到作为焊接结构件的要求。

添加纯钛夹层对TA15钛合金电子束焊接接头力学性能的影响

为了进一步优化TA15钛合金电子束焊接接头的强韧性匹配,研究了添加纯钛夹层对焊接接头力学性能的影响。利用扫描电镜对焊接接头显微组织进行了表征,对添加不同纯钛夹层条件下焊接接头的硬度、拉伸性能、冲击韧性、断裂韧性进行对比分析。研究结果表明:添加纯钛夹层对焊缝显微组织形态无明显影响;焊缝熔合区中部硬度存在低谷,而硬度在热影响区则出现峰值。

TA15钛合金电子束焊接接头高周疲劳性能研究

研究了TA15钛合金电子束焊接接头的高周疲劳性能和疲劳断口的金相组织,得到TA15钛合金棒状母材和2种电子束焊接接头的中值疲劳寿命,计算得到了电子束焊接接头99%可靠度和95%置信度水平上的安全疲劳寿命,分析了断口金相组织结构对疲劳性能的影响。研究结果可对TA15钛合金电子束焊接接头结构的工程应用提供参考。

TC17合金电子束焊接接头高周疲劳失效行为研究

电子束焊接构件广泛应用于航空发动机关键部位,其需要满足长寿命与高可靠性的设计要求.针对TC17合金电子束焊接接头,采用旋转弯曲疲劳试验方法,获得焊接接头的高周疲劳性能,同时利用电子扫描电镜对疲劳断口进行微观观察,探明焊接接头的高周疲劳裂纹萌生和扩展机理.结果表明,TC17合金电子束焊接接头在10~7周次的疲劳强度为450 MPa,约为母材强度的81%,试样失效位置均位于焊缝区;试样表面最大应力与内部气孔缺陷处应力集中形成竞争机制,在10~5~10~7周次内,裂纹萌生于内部气孔,在10~7周次后,裂纹萌生于试件表面;试样断口显示出明显的穿晶断裂区和沿晶断裂区,疲劳寿命随沿晶断裂区的应力强度因子下降而增加;气孔面积及真实应力为影响疲劳寿命的主要因素,气孔处应力强度因子与疲劳寿命呈线性下降关系.

退火处理对粉末冶金Ti_(2)AlNb合金电子束焊接接头显微组织和拉伸性能的影响

研究了焊态和退火处理态粉末冶金Ti_(2)AlNb合金电子束焊接接头的显微组织与拉伸性能。结果表明,焊态下熔合区为单一B2相,由粗大的柱状晶和等轴晶组成。经800~900℃焊后退火处理后,熔合区B2相内析出板条O相,形成O+B2相两相结构,随着退火温度升高,熔合区内O相尺寸增加,O相体积分数变化不大。焊接接头中熔合区显微硬度高于母材,焊后退火处理后,熔合区显微硬度升高,随着退火温度升高,熔合区显微硬度逐渐降低。焊态下,焊接接头表现出较高的室温拉伸强度和塑性,但在650℃高温拉伸时,焊接接头试样在未达屈服点时即在熔合区发生脆性断裂。经焊后退火处理,焊接接头室温拉伸强度和塑性略有降低,高温拉伸强度和塑性均显著改善,高温抗拉伸强度随退火温度升高而逐渐增加。

长光栅电子接长技术

本文叙述用两个或两个以上光栅读数头和一个或一个以上的短光栅尺组成的光栅测长系统。采用光栅信号细分后的脉冲相互切换计数技术,实现用短光栅尺测量大长度的目的。一次切换误差小于一个脉冲当量,达到精确测长的要求。

TC18钛合金电子束焊接接头DFR常规及腐蚀疲劳对比研究(英文)

通过对TC18钛合金电子束焊接接头在常规和3.5%NaCl水溶液腐蚀环境下的DFR腐蚀疲劳试验对比研究,试验结果计算得到在常规环境下TC18钛合金焊接件的疲劳额定强度截止值为725 MPa,其疲劳额定强度截止值为554 MPa,在腐蚀环境下,疲劳额定强度截止值下降23.6%。断口分析表明,疲劳断口有疲劳源区、疲劳裂纹扩展区和瞬断区3部分组成。疲劳寿命越长,裂纹扩展段也越长,裂纹扩展的条纹越细。在腐蚀疲劳条件下,同时有多条疲劳裂纹形成,并沿垂直于拉应力方向扩展,疲劳断口呈现多平面特征。断口表面可以发现较多的盐颗粒,说明在腐蚀溶液的作用下,盐溶液沿着疲劳裂纹的渗透性很强,在疲劳裂纹带上可以发现很多网状的盐颗粒,对TC18钛合金电子束焊接接头的疲劳性能有一定影响。

Fatigue behavior of AZ31B magnesium alloy electron beam welded joint based on infrared thermography

Fatigue behavior of AZ31B magnesium alloy electron beam welded joint undergoing cyclic loading was investigated by infrared thermography. Temperature evolution throughout a fatigue process was presented and the mechanism of heat generationwas discussed. Fatigue limit of the welded joint was predicted and the fatigue damage was also assessed based ontheevolution of the temperatureand hotspot zone on the specimen surfaceduring fatigue tests. The presented results show that infrared thermography can not onlyquicklypredict the fatigue behavior of the welded joint, but also qualitatively identify the evolution of fatigue damage in real time. It is found that the predicted fatigue limit agrees well with the conventionalS-Nexperimental results. The evolution of the temperatureand hotspot zone on the specimen surface can be an effectivefatigue damage indicatorfor effectiveevaluationof magnesium alloy electron beam welded joint.

Structure and mechanical properties of aluminum alloy/Ag interlayer/steel non-centered electron beam welded joints

Electron beam welding was carried out between aluminum alloy and steel with Ag interlayer. Seam morphology, structure and mechanical properties of the joints were investigated with different action positions of the electron beam spot. The results show that with the increment of the beam offset to the silver side from the interface between silver and steel, the seam morphology was improved, and the porosity in the Ag interlayer vanished. A transition layer mainly composed of Ag2Al and Al eutectic was formed at the interface between silver and aluminum, and became thin and spiccato as the beam offset increased. When the beam offset was too large, two IMC layers composed of FeAl and FeAl3 respectively were formed at the interface between steel and Ag interlayer. The optimal beam offset was 0.2 mm, and the maximum tensile strength of the joint was 193 MPa, 88.9% that of the aluminum alloy, and the fracture occurred at the interface between steel and Ag interlayer.

Electron beam welding of 304 stainless steel to QCr0.8 copper alloy with copper filler wire

Electron beam welding （EBW） of 304 stainless steel to QCr0.8 copper alloy with copper filler wire was carried out. Orthogonal experiment was performed to investigate the effects of process parameters on the tensile strength of the joints, and the process parameters were optimized. The optimum process parameters are as follows：beam current of 30 mA, welding speed of 100 mm/min, wire feed rate of 1 m/min and beam offset of-0.3 mm. The microstructures of the optimum joint were studied. The results indicate that the weld is mainly composed of dendriticαphase with little globularεphase, and copper inhomogeneity only occurs at the top of the fusion zone. In addition, a melted region without mixing exists near the weld junction of copper side. This region with a coarser grain size is the weakest section of the joints. It is found that the microhardness of the weld decreases with the increase of the copper content in solid solution. The highest tensile strength of the joint is 276 MPa.

BD480 型转杯纺纱机纺制C18.2 tex纱的实践

探讨在BD480型转杯纺纱机上纺制C 18.2 tex的最佳工艺。在做好原料选配和工艺路线选择的基础上,对熟条定量、转杯速度、分梳辊速度、工艺负压、排杂负压等工艺参数进行优选,采用Burmaster MB2+电子接头技术,利用BD480型转杯纺纱机的一系列优势,成功纺制出满足用户要求的C 18.2 tex转杯纱。认为:纺制的C 18.2 tex转杯纱最优工艺为熟条定量24 g/5 m,转杯速度90000 r/min,分梳辊速度8000 r/min,工艺负压5000 Pa,排杂负压1100 Pa。

Experimental Study on Heat Transfer Enhancement of Natural Circulation Liquid Cooling System for Electronic Component

The present research is an experimental study on heat transfer characteristics of a natural circulation cooling system for electronic components. A smooth chip and two micro-pin-finned chips were tested. The chip is mounted on the base of a rectangular horizontal duct located at the bottom of 250 mm high natural circulation loop.FC-72 is used as a coolant. The test conditions are set that the operation pressure of experimental system is 1. 013× 105 Pa, the flow rate of FC-72 is 150 g/min and the subcoolings are 10 K, 25 K and 35 k, respectively. Effect of the subcooling on nucleate boiling and critical heat flux(CHF) were investigated. The results show that subcoolingis found to significantly affect CHF for all chips and micro-pin-finned chips sharply enhanced the boiling heat transfer, CHF of micro-pin-finned chips are 2.5～3 times as large as that of smooth chip at the same subcooling.

Interfacial characteristics of high frequency induction brazed Cu and pre-metalized graphite joints

Oxygen-free copper and pre-metalized graphite were brazed using CuNiSnP braze alloy by high frequency induction heating method. Interracial microstructures and reaction phases were analyzed by scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDS）. The strength and resistance of the joints were tested. It is found that when the brazing parameters are optimized, the structures of the joints are graphite/（Cu,Ni）/Ni（s.s）＋NixPy/Cu3P＋Cu（s.s） （including Sn）＋eutectic structures （Cu3P＋Ni3P＋Cu（s.s）/Cu （s.s）/Cu）. When the temperature increases to 750℃ or the holding time prolongs to 300 s, the eutectie structures disappear and the amount of Cu3P increases. The maximum shear strength of the joints is 5.2 MPa, which fracture at the interface of graphite and metallization. The resistance of the joints is no more than 5 mΩ.

TA15钛合金电子束焊接接头高周疲劳性能研究

研究了TA15钛合金电子束焊接接头的高周疲劳性能和疲劳断口的金相组织。得到TA15钛合金棒状母材和2种电子束焊接接头的中值疲劳寿命，计算得到了电子束焊接接头99％可靠度和95％置信度水平上的安全疲劳寿命，分析了断口金相组织结构对疲劳性能的影响。研究结果可对TA15钛合金电子束焊接接头结构的工程应用提供参考。