低VOC低成膜温度水性聚氨酯分散体的合成与表征

以环氧树脂、甲基丙烯酸甲酯(MMA)和丙烯酸羟丙酯(HPA)复合改性水性聚氨酯(WPU),制得以丙烯酸酯为核,聚氨酯为壳,HPA为核壳之间桥连的核壳交联型PUA复合乳液。实验研究结果表明:这种复合乳液可以达到较高硬度漆膜(1H以上),最低成膜温度(2～5℃左右)。MMA添加量增大,涂膜硬度、耐水性逐渐提高,乳液的稳定性则随着降低。当MMA含量为20%左右时综合性能较好。     

新疆苏吉泉石墨矿床中的纳米石墨锥的结构表征

在新疆苏吉泉花岗岩所含团块状石墨中发现许多纳米级锥状矿物,经高分辨电镜能谱分析其化学成份为碳,电子衍射和高分辨分辨像分析表明其为纳米石墨锥.锥的顶角一般在15.5o～36.0o之间.在高分辨电镜观察基础上,讨论了纳米石墨锥的形成机制.根据三元长石温度计计算,纳米石墨锥的形成温度分别为480～950℃,压力为511～878MPa.     

Agile manufacturing of a micro-embossed case by a two-step electromagnetic forming process

A very agile method, that relies solely on simple single-sided tooling, to form open-box-like enclosures with surface detail such as highly embossed surface features is demonstrated and analyzed. For example, this method may be used to fabricate personal electronics cases. The technique uses electromagnetic forces in a two-step process. In the first step a newly developed uniform pressure electromagnetic actuator is used to make a micro-embossed pre-form that can contain very fine surface detail in the part by micro-embossing features in the forming die. This blank is then trimmed. In the second major step electromagnetic flanging is used to give greater depth and steeper walls to the case. Both electromagnetic operations use one-sided tooling and very light equipment. In principle the tooling needed for this type of process can be put to use within days or hours of finalizing the component design and precise tooling tolerances or precise alignment are not required. This work shows the essential feasibility of this approach to manufacturing either small or large lots of components.     

汽车轻量化条件下先进高强钢的发展及现状

介绍了轻量化条件下汽车车身用材的 4 种设计路线，结合具体车型说明了混合用材车身设计的发展趋势，讨论了钢板、铝合金、碳纤维车身用材的优缺点，客观评价了钢铁材料在汽车轻量化条件下的应用前景。总结了 2008～2018 年汽车车身 3 大部位使用先进高强钢强度等级的发展过程，以日本JFE公司为例，介绍了其研发的最新车身用材的力学性能及在一款新车型车身上的设计应用。同时，针对高强钢在冲压成形过程中容易产生冲压裂纹、冲压皱折和冲压尺寸偏差等问题，介绍了该公司相应的新技术及应用效果。     

洗发水瓶盖注射模设计和工艺分析

注射成型是重要的塑料成型方式,成型中工艺参数对塑件质量有重要影响。通过对洗发水瓶盖的工艺分析,确定零件的生产方案并设计了二次分型注射模具。在模具中设计了螺纹脱模机构、通过控制运动方向的特殊弧形侧抽芯机构、浇注系统、螺纹转动保险机构和温度控制系统的结构设计,对该注射模具的设计过程进行了全面的阐述。     

异形孔加强片级进模设计

通过对异形孔加强片零件的工艺分析,确定了该零件多工位级进模冲压成形的排样方案及相应的模具结构.     

Numerical and Experimental Evaluation of Springback in Advanced High Strength Steel

The automotive industry is using more and more of Advanced High Strength Steel in order to reduce the weight of the car. Since this will generate more springback, it is of vital importance to be able to predict the amount of springback in the parts. Otherwise, many late changes have to be made in order to fit the parts in their position. In order to increase the ability to understand and test the behavior of the springback in sheet-metal parts, a new semi-industrial experimental tool, the flex-rail, has been developed. This is a very flexible tool, which can be used for various kinds of materials, from mild steel and aluminum to advanced high strength steel such as TRIP-steel and CP-steel by using different insert. The tool is designed for experimental analysis of 3D-springback, which is the case in the more complicated automotive parts, such as b-pillars and side members. The scope of this work is to analyze the springback behavior and prediction for Advanced High Strength Steel both numerically and experimentally. Sheet-metal-forming simulations were made in LS-DYNA. The results proved that the new geometry, flex-rail, gave a complex springback behavior for all tested materials. Furthermore, the prediction of springback showed good correlation in sections with small amounts of twist but that LS-DYNA under-predicts the springback for sections with large amounts of twist for all materials except DP600. This article was presented at Materials Science & Technology 2006, Innovations in Metal Forming symposium held October 15-19, 2006 in Cincinnati, OH.     

电磁无接触成形过程熔体形状的数值模拟及实验研究

应用有限元方法模拟计算了电磁约束成形过程中感应器结构、固／液界面位置、熔体上顶面位置、电流频率及熔体种类对熔体形状的作用规律。结果表明：喇叭形内壁的感应器中熔体可获得侧面基本垂直的理想形状；固／液界面、熔体上顶面位置对熔体形状有明显的影响：电流频率的变化对熔体成形形状的影响很小：在感应器结构、固／液界面及熔体上顶面位置等确定后，合金种类对熔体形状几乎没有影响。同时对电磁成形规律进行了研究，表明实验与模拟计算的结果取得了很好的吻合。用电磁成形方法完成了Al合金、TiAl化合物和Ni基高温合金的无接触成形，制备出了样件，并对组织实现了定向控制。     

Mechanism of Springback-Free Bending of High-Strength Steel Sheets under Warm Forming Conditions

Tensile loading-unloading tests of high-strength steel sheets in an elevated temperature range are conducted using a 100 kN servo-controlled hydraulic dynamic fatigue testing machine, aiming at clarifying the mechanism of the springback-free phenomenon occurring in warm sheet forming. From stress-strain curves obtained by the tests, it is found that the abrupt decrease in the springback of formed steel sheets at approximately 750 K in isothermal v-bending tests is mainly caused by high-temperature transient creep deformation. Also, from the results obtained by the isothermal v-bending test, bending-unbending deformation observed at temperatures higher than 750 K, as a result of high-temperature creep, was found to have a secondary effect in the springback-free phenomenon.     

CMT电弧增材制造316L不锈钢成形精度与组织性能分析

以冷金属过渡电弧增材制造的方法成形了316L奥氏体不锈钢单道多层薄壁件,分析了不同焊接参数下材料的成形宽度、侧面成形误差、沉积有效率以及显微组织的变化. 结果表明,随着焊接速度的减小,成形试样的宽度逐渐增大;随着热输入的增加,侧面成形误差呈先减小后增大的趋势,沉积有效率呈先增大后减小的趋势,侧面成形误差与沉积有效率的变化相反. 沉积效率越大,侧面成形误差越小,成形有效率可达到90%以上. 成形件显微组织为γ-Fe和δ铁素体,δ铁素体形貌有树枝状和蠕虫状两种. 显微硬度测试结果显示在垂直于沉积方向和平行于沉积方向硬度值变化不大,这与各方向成形材料的显微组织比较均匀有关.