板材成对液压成形工艺加载路径对成形性的影响(英文)

板材成对液压成形可以用于制造复杂几何截面的空腔构件,通过合理的工艺加载路径可以实现板材的流动控制。研究非焊接板材成对液压成形工艺以及两个主要工艺参数(合模力和液压力)的影响。通过理论计算研究不同合模力对应的极限液压力,得到极限液压力曲线,揭示不同工艺参数组合对变形行为的影响规律。通过有限元分析和实验研究验证了理论值,结果表明它们之间具有较好的一致性。实验采用2种线性加载路径和1种阶梯型加载路径研究加载路径对变形行为和零件成形性的影响,结果表明采用阶梯型加载路径可以得到很好的成形性。     

加载路径对铝合金航空复杂薄壁构件主动式充液成形性能的影响

针对目前航空用铝合金复杂薄壁构件充液成形难度大的技术瓶颈,采用非线性有限元软件DYNAFORM对不同加载方式下的某铝合金大尺寸加强框零件的充液成形过程进行了数值仿真,其中液力加载路径包括线性加载、三角波脉动加载、梯形波脉动加载。采用单一变量控制法,重点分析了在脉动加载条件下振幅、频率以及波形等关键参数对零件成形性能的影响规律,并选取最优工艺参数进行了实验验证。结果表明,线性加载路径下零件开裂几率较大,成形困难,而脉动加载路径下零件成形性显著提高且易于贴模,采用梯形波脉动加载时,由于存在保压过程,成形后零件壁厚更加均匀,减薄率最小。此外,当振幅为4 MPa、频率为0. 3 Hz时,壁厚及减薄率的控制效果最好。最终获得的实际零件的成形质量优异,满足工程生产要求。     

固定碗冷挤压工艺及模具设计

通过对固定碗零件冷挤压工艺进行了分析，介绍了固定碗零件冷挤压工艺及设备选择，分析了高分子润滑剂和磷化皂化的特点，提出了采用高分子润滑剂进行毛坯润滑，介绍了镦扁的目的，挤压模具结构设计，实现了该零件冷挤压加工的顺利进行。     

内压加载路径对汽车前梁内高压成形质量的影响

为了探索工艺参数对内高压成形工艺的影响,对异型截面的汽车前梁内高压成形过程进行了实验研究,材料选用3A21铝合金,采用了两类内压加载路径,对成形外观及壁厚分布进行了比较和分析。实验结果表明,低压合模高压整形的双线性加载较单线性加载路径在成形外观、壁厚分布以及防止缺陷方面优越很多。圆弧过渡区是异型截面零件最大减薄处,双线性加载情况下减薄率达到12％,是容易发生破裂缺陷的区域。     

用氟硅酸钠,硫酸铝,食盐为主要原料合成冰晶石

本文介绍用氟硅酸钠、硫酸铝、食盐为主要原料合成高分子比冰晶石的工艺过程,找出了除去冰晶石产品杂质的条件,得到了能制出优质高分子比冰晶石的结论。     

高分子润滑剂在挤压中的应用

润滑剂在挤压过程中非常重要。本文对黑色金属冷挤压用的高分子润滑剂作了一些论述，阐述了高分子润滑剂的润滑机理，结合实际生产，讨论了润滑剂的使用方法，并与传统的磷化皂化工艺进行了详细对比。分析讨论了该润滑剂在温挤压中的应用。     

高分子薄膜润滑在板料拉深中的应用研究与发展趋势

介绍了高分子薄膜润滑在板料拉深中的应用研究与发展趋势,分别从高分子摩擦润滑的机理、板料成形中高分子薄膜的润滑工艺以及高分子润滑材料的摩擦学研究3个方面概述了目前高分子薄膜润滑的研究及应用现状、高分子润滑剂的润滑特点,简述了高强度钢板拉深成形中存在的问题和高强度钢板成形时采用高分子薄膜进行润滑会获得良好的成形性能,并指出高分子薄膜润滑存在的问题和发展趋势。     

某大型航空铝合金锻件局部加载成形质量控制

以某大型铝合金航空锻件为对象,针对整体一次加载成形时载荷过大的问题,提出了局部加载成形工艺方案,利用有限元法对锻件分段局部加载成形充填和载荷、多道次之间变形量分配及各道次加载顺序进行了研究。结果表明:该铝合金大锻件采用整体加载方案时,最大成形载荷为400 MN,超过了现有设备能够提供的载荷;采用局部加载3段2道次成形时,每道次成形载荷均可控制在300 MN以内,第1道次上下模具停止距离为55 mm,且加载方式为从锻件中间往两边加载,能够获得填充完整的锻件,满足现有设备要求。     

基于ANSYS分析的螺栓组拧紧工艺研究

构建了盘式螺栓组连接有限元模型;运用ANSYS设置载荷步模拟螺栓组分步拧紧全周期;通过对多次分步加载仿真计算得到:分步拧紧会降低螺栓间残余预紧力分布不均的程度,改善结合面的应力分布状况.并得到了残余预紧力和结合面接触应力的标准差随分步加载步数的变化规律.进而用此规律对某型发动机盘式螺栓组现有拧紧工艺进行优化,ANSYS仿真结果表明优化后工艺较原工艺拧紧效果更好,对工程应用具有一定的指导意义.     

铜合金三通多向加载挤压成形工艺数值模拟与试验

利用有限元分析软件MSC-Superform模拟铜合金三通多向加载方式的成形过程。通过对多向同步、分步、顺序加载3种不同成形方式的模拟,得出了多向分步加载成形为较佳的工艺方案。根据模拟的工艺参数进行试验,验证了铜合金三通成形工艺参数、模具结构的正确性及可行性,可为类似零件的成形提供参考。     

过程参数对微型机械模内组装成型流固耦合变形影响

聚合物模内组装成型,是解决聚合物微型机械成型加工技术难题的先进成型技术,其成型的微型零件的制造精度和零件组装配合精度,主要受控于二次成型熔体充填流动与固体微型零件之间的流固耦合作用。该文通过有限元数值模拟技术,研究聚合物微型机械模内组装二次成型过程参数,对一次成型固体微型零件的流固耦合作用效应和流固耦合变形的影响规律。研究结果表明,增加二次成型熔体注射速度,可使二次成型熔体的充填流动与一次成型固体微型轴表面间的流固耦合作用效应增强,并使一次成型微型零件整体温度场趋于均匀,从而导致一次成型固体微型零件流固耦合弯曲应力和弯曲变形增加,热应力和热变形减小;降低二次成型熔体注射速度,可提高聚合物微型机械模内组装成型的成型加工精度及组装配合的精度。     

KH-550对聚合物矿物复合材料力学性能的影响

钢纤维增强聚合物矿物复合材料(SFPMC)中,聚合物基体、钢纤维、骨料和填料组成多相界面,利用KH-550偶联剂改善界面结合状态,进而提高材料力学性能.选取不同长径比和含量的钢纤维制备SFPMC,研究了经过KH-550表面偶联处理和未经KH-550表面偶联处理的钢纤维对聚合物矿物复合材料强度的影响,并分析了KH-550的偶联作用.试验结果表明:与采用未经偶联处理钢纤维的试件相比,采用经KH-550偶联处理钢纤维的试件抗压强度提高显著,最大抗压强度可达110.8MPa,比采用未经偶联处理钢纤维的试件提高了13.68%.     

粘结剂和添加剂对注射成型各向异性粘结NdFeB磁体的影响(英文)

研究了在取向磁场下由HDDR磁粉注射成型的各向异性粘结NdFeB磁体,分析了粘结剂和添加剂对各向异性粘结NdFeB磁体的密度、磁性能以及抗压强度的影响.通过磁粉表面改性,磁粉的抗氧化性能以及磁体的磁性能都得到提高.比较了6种粘结剂对磁体性能的影响,从中得到比较理想的粘结剂,并且考察了抗氧剂以及润滑剂加入量对于磁体性能的影响.试验中,混炼温度为205～215 ℃,注射温度为265℃,注射压力为5～6 MPa,保压时间为5 s,模具加热温度为80℃.制得的磁体的性能为:Br=0.72 T,iHc=983 kA/m,(BH)max=75 kJ/m3.     

Numerical simulation of mould filling process for pressure plate and valve handle in LFC

In lost foam casting (LFC),the distribution of polymer beads during the bead filling process is not uniform,and the collision between polymer beads determines the distribution of two-phase flow of gas and solid.The interaction between the gas and solid phases reveals as coupling effect of the force that gas exerts on particles or vice versa,or that among particles.The gas-solid flow in filling process is nonlinearity,which makes the coupling effect an essential point to carry out a simulation properly.Therefore,information of each particle's motion is important for acquiring the law of filling process.In bead filling process,compressed air is pressed into mold cavity,and discharged from gas vent,creating a pressure difference between outer and inner space near the gas vent.This pressure difference directly changes the spatial distribution and motion trace of gas and solid phases.In this paper,Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) are employed to simulate the fluid dynamic character based on Newton's Third Law of Motion.The simulation results of some casting products such as pressure plate and valve handle are compared with the result obtained from practical experiment in order to test the feasibility of DEM.The comparison shows that this DEM method can be a very promising tool in the mould filling simulation of beads' movement.     

Investigation of the effect of substituent on the growth of polymer for 3-substituted polythiophenes via pyrolysis mass spectrometry

In this study, direct pyrolysis mass spectrometry analyses of electrochemically polymerized poly(decanedioic acid bis-(2-thiophen-3-yl-ethyl)ester) and poly(terepthalic acid bis-(2-thiophen-3-yl-ethyl)ester) were performed to investigate structural and thermal characteristics. It was found that when the ester linkages contain hydrocarbon chains, the growth of polymer occurred through both 2- and 5-positions. On the other hand, when the ester linkages contain more rigid groups such as phenyl, steric hindrance inhibited the growth of the polymer through 2-position and polymerization proceeded via coupling of thiophene moieties mainly at 5-position yielding a polymer with a lower conductivity.     

SiOx纳米抗菌剂制备及在羊毛纤维中的应用研究

利用纳米SiOx的多孔结构,采用离子交换法制备纳米SiOx抗菌剂,使用硅烷偶联剂对纳米抗菌剂进行表面改性,降低其表面自由能,并初步探讨了该抗菌剂在羊毛纤维中的应用。经测试表明,纳米抗菌剂的抗菌率可达96％以上;表面改性可增强纳米抗菌剂与高聚物的相容性,用该抗菌剂制备的抗菌羊毛纤维,在具备抗菌功能的同时,又具有良好的力学性能。     

Mechanistic studies of the electropolymerization of 2,2′-bithiophene and of pyrrole to form conducting polymers

The electropolymerizations of 2,2′-bithiophene and of pyrrole to form conducting polymers were investigated by several electrochemical methods. Cyclic voltammetry indicates that a peak at 1.1 V is associated with the polymer and that the same product is formed from thiophene as from 2,2′-bithiophene. The rate of polymer formation has a zero kinetic order dependence on monomer concentration for polymerization of pyrrole or 2,2′-bithiophene. A dependence on concentration of supporting electrolyte is interpreted as a consequence of anion diffusion and oxidative doping in the polymer. The kinetic results are consistent with an oxidative coupling mechanism for polymer formation. The electrochromic switching of the polymer film was investigated by spectroelectrochemical methods and the kinetics were examined over a range of film thicknesses.     

基于体壳耦合模型的钛合金薄板激光焊接变形分析

针对钛合金薄板激光焊接变形的数值模拟提出了一种高效体壳耦合模型,即在近缝区采用实体单元以充分表征焊接过程中板材厚度方向的热/力学不均匀性,在远离焊缝区采用壳单元建模以减小单元数量,在两种单元的界面建立接触并采用MPC算法进行焊接变形计算. 采用体壳耦合模型与三维实体模型分别计算了0.8 mm厚TC1钛合金激光焊接变形. 结果表明,两种模型的计算值均与试验测量值相近,但体壳耦合模型耗时仅为三维实体模型的30%左右,表明体壳耦合模型在保证计算精度的前提下能显著提高计算效率.     

Integration of polymer elements at the end of optical fibers by free-radical photopolymerization

In this article, we report a method of free-radical photopolymerization on the top end of a single-mode optical fiber. The process is very simple to carry out and uses the visible light guided in the fiber. It permits one to produce, on the fiber end, a micronic polymer tip which may be viewed as an extension of the fiber core and whose optical properties improve the intrinsic capability of the fiber, particularly in terms of efficiency of coupling with a laser source. Formation of the tip is explained by self-guiding of the light within the material and photophysical response of the material.     

All-optical light modulation in anthraquinone dye doped waveguides based on an improved prism coupling method

In this paper, an improved all-optical light modulation scheme has been proposed with respect to photo-induced changes of the refractive index of polymer planar waveguides by the m-line spectroscopy technique. An improved prism coupling method was used to realize it. In this prism coupling configuration, the strong pump (writing) beam excited by an Ar⁺ laser at 514 nm is illuminated on film sample by passing through the upper base of prism, and induces local refractive index changes by heating. A probe (reading) beam, which is coupled into prism coupling system and forms waveguide modes in film, is modulated for its changes of reflectivity due to changes of refractive index of waveguide film. A shift of sharp guided wave resonance is observed and 20 ms of response time is obtained.