新型钢管脚手架十字扣件的研制

新型钢管脚手架十字扣件又称钢管脚手架快速十字扣件，是国家专利产品，该种扣件与传统的钢管脚手架十字扣件相比，结构上用一楔子代替了两个螺栓，装卸方便快速，可重复使用，使用寿命大大提高，材质上用铸态球墨铸铁ＱＴ４５０－１０代替了传统扣件使用的玛钢ＫＴ３８０－８，机械性能好，生产成本低，生产效率高。     

锻压温度对钢制机械扣件性能的影响

采用不同温度进行了钢制机械扣件的锻压试验,并进行了力学性能和腐蚀性能测试。结果表明:锻压温度对扣件力学性能和耐腐蚀性能有明显影响。在试验条件下,随始锻温度从1170℃增大到1290℃、终锻温度从680℃增大到760℃,扣件力学性能和耐腐蚀性能均先提高后下降。扣件的始锻温度和终锻温度分别优选为1260、720℃。     

压铸工艺对ADC12铝合金建筑脚手架扣件力学性能和腐蚀性能的影响

采用不同的模具温度和浇注温度进行了ADC12铝合金脚手架扣件压铸试验,并进行了力学性能试验和腐蚀试验。结果表明:在试验条件下,随模具温度从200℃增至350℃或浇注温度从680℃增至740℃时,扣件的力学性能和腐蚀性能均先增加后减小。与200℃模具温度相比,模具温度275℃时压铸的ADC12铝合金脚手架扣件的抗拉强度增大33 MPa,断后伸长率减小0.9%,腐蚀电位正移116 m V;与680℃浇注温度相比,710℃浇注时压铸ADC12铝合金脚手架扣件的抗拉强度增大30 MPa,断后伸长率进减小0.7%,腐蚀电位正移94 m V。ADC12铝合金脚手架扣件压铸时的模具温度和浇注温度分别优选275、710℃。     

低碳马氏体扣件弹条的研究

利用低碳马氏体的强韧化机理，采用低碳合金钢代替中碳弹簧钢进行Ⅰ型扣件弹条的生产。制作的扣件弹条经适当温度淬火及回火后勘和学性能指标完全满足和超过ＴＢ／Ｔ１４９５．２－９２中所规定的各项性能指标。     

新型建筑铸钢扣件的铸造工艺研究

在1475～1575℃浇注温度、1～9 min浇注时间内,进行了ZG25CrV新型建筑扣件的铸造试验,并进行了耐磨性和耐蚀性的测试与分析。结果表明,扣件耐磨性和耐蚀性随浇注温度提高、浇注时间延长而先提高后下降。浇注温度不宜过高也不宜过低,浇注时间不宜过长也不宜过短。与1475℃浇注温度相比,1550℃浇注时扣件的磨损体积(10.5×10~(-3)mm~3)减小57.7%,腐蚀电位正移135mV(-0.824→-0.689V);与9 min浇注时间相比,当浇注时间为3 min时扣件的磨损体积(10.5×10~(-3)mm~3)减小51.6%,腐蚀电位正移129 m V(-0.818→-0.689V)。ZG25CrV钢建筑扣件的浇注温度和浇注时间分别优选为1550℃、8 s。     

水溶性淬火介质KR9180在弹条扣件淬火中的工艺试验

介绍了水溶性PVP类有机淬火介质KR9180的特性,并使用浓度为15%的KR9180淬火剂对弹条扣件进行了淬火试验。结果表明,用浓度为15%的KR9180水溶性淬火剂代替油淬火,弹条扣件的硬度、显微组织及疲劳性能均能满足技术要求。     

合页扣件级进模设计

通过对合页扣件的成形进行工艺分析,指出冲压成形过程中的关键点,制定了合理的冲压工艺,设计了生产合页扣件的精密级进模,灵活布置浮顶镶件控制成形。实践证明,模具结构合理、可靠,生产的零件合格,对类似零件的成形有一定的参考作用。     

锻压工艺参数对Q235-Cr钢建筑脚手架扣件性能的影响

采用不同的工艺参数对Q235-Cr钢建筑脚手架扣件进行了锻造,并对试样进行了耐腐蚀性能和冲击性能的测试与分析。结果表明:在试验条件下,随始锻温度从1200℃升高至1300℃,终锻温度从685℃升高至745℃或锻压速度从20 mm/min增大至50 mm/min,扣件的耐腐蚀性能和冲击性能均先提高后下降。扣件的最佳锻压工艺参数为:始锻温度1275℃、终锻温度715℃和锻压速度40 mm/min。     

山地城市地铁制动/轨道结构参数对钢轨波磨的影响

目的 山地城市地铁相较于平原城市地铁具有爬坡大且曲线多的复杂线路特点,其钢轨波磨问题更加严重。探究山地城市地铁制动区间钢轨波磨的形成机理,提出相应钢轨波磨的控制方法。方法 首先,结合现场调研建立了轮对-轨道-制动系统的有限元模型。然后,采用复特征值分析法研究了轮对-轨道-制动系统的摩擦自激振动特性,进而对制动闸片的表面织构及扣件参数进行参数化分析。最后,基于最小二乘法,采用2种拟合方程对扣件参数进行多参数拟合,并采用遗传算法与粒子群算法确定抑制钢轨波磨扣件参数的最优解。结果 发现轮对-轨道-制动系统存在2个不稳定振动频率,分别为653.73 Hz与584.76 Hz,其中653.73 Hz的复特征值实部较大,为46.53。对比不同表面织构,采用正六边形织构表面闸片的轮对-轨道-制动系统复特征值实部最小,为19.46。对比扣件参数优化前后,采用优化后的扣件参数的轮对-轨道-制动系统复特征值实部较小,为0.49。结论 轮轨子系统与制动子系统的摩擦耦合作用导致轮对-轨道-制动系统摩擦自激振动,是诱导山地城市地铁制动区间钢轨波磨产生的重要因素。当采用正六边形表面织构闸片或设置扣件参数中垂向刚度为36.2 MN/m,垂向阻尼为2 800 N.s/m,横向刚度为25 MN/m,横向阻尼为2 000 N.s/m时能有效抑制钢轨波磨的产生。     

南钢高铁弹簧钢市场占有率国内第一

正截至2017年底,用南钢高铁弹簧钢生产的高铁扣件已累计应用于国内17条高铁线,占国内市场25%的份额,市场占有率和业绩国内排名第一。同时,南钢作为第一牵头单位参与制定了国家标准《高速铁路扣件用弹簧钢热轧盘条》。2006年,我国高铁还处于探索起步阶段,南钢就已开始着手高铁扣件用钢的研发。在此之前,我国铁路经过5次提速,迈入了"铁路高速化时期"。南钢敏锐地察觉到,对高铁用钢必须早研发、早进入。但是,当时国内并无开发高铁用     

吸尘器弯管接头注射模设计

分析了吸尘器弯管接头的结构,对具有整圈内置卡扣特征的塑件,设计了复合抽芯的内缩结构,实现弯管接头卡扣的顺利脱模,采用此方法提高了生产效率。经生产实践证明:模具结构可靠,生产的塑件满足要求。     

SMT建模仿真研究现状及发展

概述了SMT再流焊工艺过程、所用组装件以及形成的焊点3方面的仿真进展，充分展现了计算机模拟在再流焊研究中的重要作用。     

Interfacial Design for Joining Technologies: An Historical Perspective

This paper gives an historic perspective of the concept of “Interfacial Design” in joined (e.g. soldered, brazed, diffusion bonded) assemblies. During the course of history, the awareness grew that the interface in a material joint can be perceived at different length scales. With the continuing development of joining materials and technologies, it became evident that the performance of assemblies is critically dependent on the structure and composition of the multiple internal interfaces in the material joints. Resulting trends in the microstructural design of soldering, brazing, and other bonding materials by smart engineering of internal interfaces, as driven by increasingly complex technological requirements, are briefly addressed.     

Electrical measurement of a lead-free solder assembly after environmental tests by SEM internal probing

In this study, electrical characterization for lead-free materials in bump technology was developed and joint assemblies were thermally treated under temperature cycling tests. Measurements of sheet resistivity and contact resistance of intermetallic compounds (IMCs) in solder joints were conducted. Quantitative analysis and elemental redistribution of IMCs were obtained by field-emission electron probe microanalyzer. A scanning-electron microscopy internal probing system was introduced to evaluate electrical characteristics in IMCs after thermal treatments. To determine resistivity of IMCs, a novel method incorporating SELA-EM2 and a focused ion beam was developed to prepare the joint sample.     

Corrosion performance and mechanical properties of joined automotive materials

The automotive industry envisions that an optimized vehicle in terms of performance and cost can be achieved only by using different materials at different vehicle locations in order to utilize the functionality of the different materials to a full extent. Currently, steel and aluminum are the most important construction materials for the mass production of automotive structure. However, other materials such as magnesium alloys and stainless steel are also used. The use of dissymmetric assemblies of materials in the automotive industry has also led to the development of joining technologies other than spot welding and arc welding such as clinching, adhesive bonding, laser welding, and MIG brazing. However, and despite the development of these new joining technologies, there are still important gaps of knowledge with regards to the corrosion performance of different joint populations using dissymmetric and symmetric materials. Materials commonly used in the automotive industry including steel and aluminum‐based susbtrates were assembled with different combinations using various joining techniques in order to evaluate their corrosion performance as well their mechanical properties after cyclic accelerated corrosion tests. The results indicated a relationship between the corrosion inside the confined joint and the decrease of the mechanical properties of the assemblies.     

轴承感应拆装的计算机仿真研究

在研究轴承内环感应拆装的基础上,建立了感应加热过程中工件内电磁场和涡流分布的基本方程.通过MATLAB软件对被加热工件进行了电磁场和涡流分布的计算机模拟,形象描述了工件内电磁场的分布规律,证明了集肤效应的存在,为轴承感应拆卸装置的设计研究提供了理论依据.通过对感应加热过程中轴承内环内外表层温度的测试,间接证明了所建模型和计算机仿真的正确性.     

轨姿控液路分离接头流道仿真计算与分析

轨姿控系统液管路分离接头因工作过程中存在流阻和液动力大的问题而影响其自身和下面级发动机工作,因此对液管路分离接头进行优化改进具有重要应用价值。根据液管路分离接头在某型轨姿控系统中所处的位置及工作原理,从减小流阻和稳态液动力的角度出发,设计了两型液路分离接头,采用3种不同装配方式,运用CFD软件FLUENT对液管路分离接头管道内部流场进行了分析计算。结果表明:所设计的第二型、采用第一种装配方式能使液管路分离接头管道内部流场压力分布较均匀,流阻和稳态液动力较小,表明优化后的管道内部结构合理,满足设计要求。     

A comparative study of the residual deformation of an automotive gear-case assembly due to deep-penetration high-energy welding

A three-dimensional elastic–plastic finite element model was used to investigate the relative effects of different joint forms on the welding distortion and residual stresses in an automotive differential assembly due to deep-penetration high-energy welding. Numerical studies were carried out to determine optimal selections of heat generation rate and the number of weld segments to ensure both computational efficiency and accuracy of the calculation. To model the constraints and boundary conditions realistically, contact elements were used at the mating surfaces of different structural components and the shrink fit between the gear and differential case was modeled using couple sets. Two situations representing welded gear-case assemblies where the weld joints were oriented at 0° and 30° with respect to the radial direction were analyzed. Predicted welding distortions and residual stresses are compared and discussed in detail. The results indicate that the residual tensile stresses in the 0° radial joint are larger than those in the 30° angled joint and that residual distortion is sensitive to joint form.     

The effects of external loading on a yield tightened joint

If bolted assemblies are to perform adequately under service conditions it is vital that the clamp load on the joint should be as great as possible consistent with the design features of the joint. Furthermore, each fastener of the joint should exert the same clamping force if distortion and overloading are to be avoided. Recent research has shown that better consistency of clamping load can be achieved if the fasteners of the joint are tightened using a yield tightening technique rather than the more traditional torque control method. This paper examines the behaviour of fasteners tightened to yield under various conditions of lubrication. The behaviour of the yield tightened fastener under additional external loading is also examined. The results show that fasteners tightened to yield respond in an elastic manner under the initial application of an external load. It is also shown that under appropriate lubrication conditions a fastener can be repeatedly retightened to yield without failure occurring. It is felt that these results should be of particular interest to design and development engineers within industry in general and the machine tool industry in particular.     

Modelling of deformation and failure of crash toughened adhesive bonded lap shear joints

Abstract

With an increase in the use of advanced high strength steels in vehicle architectures, materials joining issues have become increasingly important. Among the various joining methods, adhesive bonding is increasingly used in automobile manufacturing. Successful implementation of adhesive bonding to improve structural crashworthiness and reduce vehicle weight requires the knowledge of issues related not only to processing but also to joint performance. In this study, a new anisotropic yield criterion which is determined from tensile and shear tests, is developed and incorporated into a finite element model to predict the static load displacement curves of various adhesive bonded steel joints. In the developed model, when the calculated plastic strain of bonded steel joint reaches the equivalent plastic strain of the adhesive the joint is regarded as failed. Modelling results have been validated by the experimental data. Since the model covers different steel grades, gages, and overlap distances, the model can be used to predict the static strengths of adhesive bonded assemblies. Finally, the model is employed to evaluate the effect dissimilar steel grades and sheet gages on the joint strength of lap shear bonded steel joints. The results show that for the joints made of dissimilar steel grade and sheet gage, the stiffness (i.e. strength and thickness) of the two adherends should be balanced to obtain the optimum joint strength.