轮胎定型硫化机曲柄齿轮过盈配合有限元分析

利用ANSYS软件内嵌的APDL语言建立了轮胎定型硫化机曲柄齿轮组件的非线性接触模型。对压装过程进行静态接触分析,并对不同过盈量下应力分布结果进行比较,验证了模型的正确性,对于确定过盈配合中合理的过盈量和改进加工工艺具有重要意义。     

浅谈大卷装拉丝丝饼常见成形缺陷的改善

通过对大卷装拉丝机丝饼成形缺陷的改善试验研究,找出影响丝饼成形的因素,找到解决方案并实施,最终确定了适合的拉丝工艺参数。经过试验验证,效果良好,提高了大卷装丝饼纱的产品质量,同时提高了生产效率。     

用弦角测量控制法确定型材成形的模拟实验与分析

船用型材冷弯成形常采用端点测量控制法,但采用该方法时,冷弯设备的检测机构庞大、操作不便、造价高、难于制造和安装。为此,提出一种弦角测量控制法代替传统的端点测量控制法实现型材的冷弯成形。为了验证该方法的可行性,采用铜线模拟型材的中性层曲线进行压弯实验,同时对压弯的支点距离、进料步长等进行分析和论证。结果表明,采用该方法获得的铜线形状与型材样条曲线基本吻合。研究结果可为型材冷弯成形提供理论依据。     

板材多点成形中回弹的数值模拟及补偿研究

回弹是板材多点成形中一个必须解决的问题。利用有限元软件LS-DYNA对板材冲压成形的回弹进行数值模拟,采用动态显式算法模拟板材成形过程,隐式算法模拟卸载回弹过程。对不同曲率半径、不同屈服强度的圆柱面成形件进行数值模拟,分析得出回弹趋势和回弹分布,提出通过修正基本体群成形面来补偿回弹的方法,并用B样条曲线拟合生成的曲面。经过两次补偿,成形件精度提高,证明该方法可以很好地补偿多点成形中的回弹。研究结果对于减小因回弹带来的误差,提高成形件的成形精度具有十分重要的意义。     

浇注温度对锆基块体合金非晶形成能力和力学性能的影响

在水冷铜坩埚中采用铜模吸铸法以不同的浇注温度制备出四个一组直径3 mm的Zr55Al1ONi5Cu30合金试样,研究了浇注温度对锆基块体合金非晶形成能力、力学性能和组织的影响.研究结果表明,提高浇注温度可以增加锆基块体合金非晶形成能力和热稳定性;当铸造电压从7 kV提高至10 kV时,过冷液相区△Tx和参数γ分别从73 K增至89K,从0.413增至0.417;同时在一定温度范围内提高浇注温度可以提高错基块体非晶合金的压缩断裂强度和轻微的降低塑性.当铸造电压升高至10 kV时,不但可以提高Zr55Al10Ni5Cu30合金试样的压缩断裂强度,同时提高其塑性,并对此原因进行了分析.     

等温变形对异种钛合金焊缝组织性能的影响

通过改变等温变形工艺参数探讨了焊缝显微组织的变化机理与焊件的室温拉伸性能。结果表明:在较低应变速率下,以较大变形量变形时,焊接界面晶粒细化与位错切过晶界和晶内的O/α2相条及O/α2发生拉长、颈缩而断开的机制有关,变形量小时则主要以位错切断晶界及晶内O/α2条为主。应变速率低(10-4s-1)和高(10-2s-1)时,出现的粗细不同条状O/α2相是与动态再结晶的响应速率有关。在980℃,以10-2～10-4s-1应变速率和30%～50%变形Ti2AlNb/TC11双合金焊接接头,可得到高于TC11合金的室温强度。     

Study on the J-Integral and Failure Assessment Line of Electron Beam Welded Thick TC4-DT Alloy Joints

The effects of strength mis-matching on J-integral and failure assessment line (FAL) of electron beam welded thick TC4-DT titanium alloy joints have been investigated.Elastic and elastic-plastic finite elements (FE) calculations on centre crack tensile (CCT) specimens were made,and the condition of 20% strength mis-matching was considered.The results indicate that the limit load of the joint can be substituted by that of the base metal.The error of substitution is less than 5%.The failure assessment lines for both over-matching and under-matching joints are increasingly close to that of the base metal,with the ratio of weld width to specimen width (H/W) decreasing.Moreover,the failure assessment lines of the joints can be devised using the stress-strain curves of the base metal,which will be convenient for the practical application of engineering structures     

Inhibit the Porosity with Electron Beam Scanning Method in Welding LD10 Aluminum Alloy

LD10 aluminum alloy is becoming widely used in aeronautics and astronautics industries for the advantages of high specific strength and good mechanical property.Aluminum alloy is an active metal with low melting point and boiling point.The porosity is apt to occur in the processing of electron beam welding.In this article,the author investigated the influence of electron beam scanning welding parameters (scanning figure,scanning frequency,focus,and welding speed) on porosity.10 mm thick LD10 aluminum alloy were welded and then tested by X-ray inspection.The experiment results indicated that rational parameters would reduce the occurrence opportunity of porosity.Using the parameters of circle scanning,high scanning frequency,focus-out,and smaller welding speed,the porosity can be significantly reduced.     

Comparative Analysis on Microstructure and Mechanical Properties between EBW and TANDEM Welding of 7A52 Aluminum Alloy Joint

The plates with 20mm thickness of 7A52 aluminum alloy were welded by electron beam welding and TANDEM welding with ER5356 filler,respectively.The microstructure and mechanical properties of the joints were investigated.The results showed that the microstructure of EBW metal was finer and tighter than TANDEM welding.The heat-affected zone of the EBW joint was narrower,its hardness was higher and the tensile strength improved obviously compared to TANDEM welding.Excellent quality control of the EBW joint was made without abnormal porosity,inclusions and micro-cracks.Therefore,the EBW joint of 7A52 aluminum alloy showed excellent performance.     

新型铜合金/非晶复合材料的挤压成形特性

基于大块非晶在过冷液相区间具有较好的热塑性成形特点,选择铜基非晶Cu40Zr44Ag8Al8和铜合金,通过挤压成形工艺,制备出一种新型的铜合金/非晶复合材料;在703 K和挤压速度为0.4 mm/min下对该复合材料进行挤压,获得铜合金、非晶复合材料棒材.通过光学金相(OM)、X射线衍射(XRD)、示差扫描量热分析(DSC)和维氏硬度测试(HV)对挤压变形前、后芯部非晶进行形貌观察和结构分析.结果表明:芯部非晶在挤压前期呈不均匀分布,而后分布非常均匀;结合XRD、DSC和硬度的结果分析,在703 K下挤压后,芯部非晶没有发生晶化.