Evaluation of friction in upsetting

Distributions of contact stresses at the neutral point in metal forming are very hard to be properly predicted due to the complex interface situation and lack of suitable friction models. In this paper, the dynamic friction model in which the friction depends on both time rate of strain and normal pressure has been applied to predict contact stresses in cylinder upsetting. Case studies have shown that the predicted results agreed with the experimental data chosen from literature. By comparing with two other friction models, the dynamic friction model seemed to give a better solution.     

电液伺服阀综合测试台的设计

介绍一种工业专用的液压伺服阀综合测试台的组成、液压系统及其测控系统的设计原理、测控软件的研发,重点阐述液压伺服阀综合测试台测试伺服阀静、动态性能的原理,提出采用压力闭环来保持伺服阀压降恒定。     

液芯率对金属形变的影响

通过模拟试验,研究了液芯轧制过程液芯率对金属形变各个因素的影响。结果表明,液芯率≤6％的F8·5吨钢锭,可以正常轧制,成品质量良好。用于初轧生产,令人感到满意。     

布袋除尘器吸风罩的研究

为了提高生活垃圾焚烧发电除尘系统除尘效率,提出除尘系统吸风罩的结构改造措施,力图通过改变吸风罩结构尺寸,以较小的风量获得良好的除尘效果.利用CFD模拟软件,对不同扩张角的吸风罩内部气固两相流动进行数值模拟.结果表明:扩张角为60°～90°时,吸风罩内部速度场分布均匀,无明显的涡流、回流.利用数值模拟可以有效地缩短设计过程,减少产品开发成本,满足现代工业设计要求.     

Rheological properties in blends of poly(aryl ether ether ketone) and liquid crystalline poly(aryl ether ketone)

Rheological properties of the blends of poly(aryl ether ether ketone) (PEEK) with liquid crystalline poly(aryl ether ketone) containing substituted 3‐trifluoromethylbenzene side group (F‐PAEK), prepared by solution precipitation, have been investigated by rheometer. Dynamic rheological behaviors of the blends under the oscillatory shear mode are strongly dependent on blend composition. For PEEK‐rich blends, the systems show flow curves similar to those of the pure PEEK, i.e., dynamic storage modulus G′ is larger than dynamic loss modulus G″, showing the feature of elastic fluid. For F‐PAEK‐rich systems, the rheological behavior of the blends has a resemblance to pure F‐PAEK, i.e., G″ is greater than G′, showing the characteristic of viscous fluid. When the PEEK content is in the range of 50–70%, the blends exhibit an unusual rheological behavior, which is the result of phase inversion between the two components. Moreover, as a whole, the complex viscosity values of the blends are between those of two pure polymers and decrease with increasing F‐PAEK content. However, at 50% weight fraction of PEEK, the viscosity‐composition curves exhibit a local maximum, which may be mainly attributed to the phase separation of two components at such a composition. The changes of G′ and G″ with composition show a trend similar to that of complex viscosity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4040–4044, 2006     

火焰切割机数控代码的二次处理

根据火焰切割机的加工工艺要求,要对数控代码进行二次处理--对数控程序进行转换或在原有的数控程序中添加代码.分析了进行代码二次处理的几种原因,重点阐述了零件加工前在零件数控代码中添加引入和引出线代码的几种不同情形及实现方法.     

Crystallization behaviour and high coercivity of （Nd,Pr）（13）Fe（80）Nb1B6 melt-spun ribbons

Amorphous (Nd,Pr)₁₃Fe₈₀Nb₁B₆ ribbons were crystallized at 670–730°C for 5–25 min to study the effects of isothermal crystallization on their behavior and magnetic properties. XRD results indicate that the isothermal incubation time is 12, 5, and less than 5 min at 670, 700, and 730°C, respectively. High coercivities, with the maximum value of _i H _c = 1616 kA/m at 700°C for 19 min, measured by a physical property measurement system, are obtained in the crystallized ribbons. This is mainly attributed to the addition of Pr and Nb, because Pr₂Fe₁₄B has a higher anisotropic field than Nd₂Fe₁₄B, and Nb enriched in the grain boundary regions can not only reduce the exchange-coupling effects among hard grains, but also impede grain growth during the crystallization process. In addition, it should also be related to the characteristics of the furnace that the authors designed.     

一种新型可乐型饮料的研制

主要研究以啤酒生产中的原料作为部分原料,辅以可乐原料,采用特殊工艺生产一种新型可乐饮料。该产品既具有黑啤酒的外观特征又具有普通可乐的口感特征,是一种介于啤酒和可乐之间的新产品。通过实验确定了新型糖化工艺、麦汁处理技术和其它工艺参数,采用此工艺生产的可乐饮料符合GB/T10792－1995标准。     

盐析辅助液液萃取结合气相色谱-质谱法测定酱油中4种氯丙醇

为满足绿色、快速筛查需求,建立盐析辅助液液萃取结合气相色谱-质谱法测定酱油中1,3-二氯-2-丙醇、2,3-二氯-1-丙醇、3-氯-1,2-丙二醇和2-氯-1,3-丙二醇的分析方法。方法 以D5-3-氯-1,2-丙二醇为内标物,酱油样品经乙腈提取,氯化钠盐析分层,七氟丁酰基咪唑衍生,HP-5MS 毛细管柱(30 m×0.25 mm,0.25 μm)分离,采用选择离子监测的气相色谱-质谱法的选择离子监测(selected ion monitoring,SIM)模式进行测定。实验考察了盐析助剂、萃取溶剂对4种氯丙醇萃取效率的影响。结果 最优实验条件下,4种氯丙醇在0.006~0.120 mg/kg范围内4种氯丙醇的线性关系良好,且相关系数都大于0.999,检出限为0.002 mg/kg,定量限为0.006 mg/kg。在0.02、0.05、0.10 mg/kg的加标水平下,4种氯丙醇的加标回收率在为70.2%~103.5%范围内,相对标准偏差(relative standard deviations,RSDs)在为1.6%~5.5%范围内。结论 本方法快速、简便、节省溶剂,适用于酱油中氯丙醇的快速定性、定量分析。     

三维四面体网格模型在固体矿产储量估算中的研究与应用

矿体储量估算涉及到大量地质数据,传统的手工计算工作量大,计算繁琐。利用计算机以三维矿体模型为基础进行储量计算,可以有效提高矿产储量估算和管理的效率。在对当前几种常用三维矿体建模方法进行分析的基础上,选择四面体网格模型来进行矿体建模,并提出了一种基于约束的四面体网格的矿体储量计算方法。该方法的主要优点在于可以通过四面体网格模型,对矿体边界以及矿体内部品位分布等进行统一的管理,计算精度高。因此,该方法具有一定的理论研究意义和实际应用意义。