用阀式顺序注射技术消除塑件表面熔接痕

应用Mouldflow软件对大型平板塑件采用阀式顺序注射成型过程进行了模拟,分析了塑件表面产生熔接痕的原因,通过控制阀浇口开闭时间和注射工艺参数的设置,达到减轻或消除塑件表面产生熔接痕的目的。     

汽车门把手塑件熔接痕产生的原因及消除方法

汽车制造中,塑料制品大量应用,塑件的质量直接影响着汽车质量。塑件注射成型中产生的不良品因素很多,其中熔接痕的产生是影响塑件质量的一个重要因素。因此,研究熔接痕的形成过程、影响因素及寻找消除熔接痕的方法具有重要的现实意义。     

基于Moldflow减轻或消除汽车储物盒熔接痕的解决方案

介绍了塑件上熔接痕的产生原因和关键因素,通过汽车储物盒的成型,采用Moldflow软件确定浇口位置的设置、预测塑件可能产生熔接痕的位置,对塑件局部壁厚进行优化后,设计的注射模生产出了满足客户要求的塑件。     

基于Moldflow的塑料玩具人前身注射工艺优化与模具设计

针对塑料玩具人前身在注射工艺中容易出现气穴、熔接痕、翘曲变形等缺陷,运用Moldflow软件进行模拟仿真分析,得到气穴、熔接痕的位置和各方向的翘曲变形量,同时选取合适的注射工艺参数,并运用UG软件对模具的成型零件进行设计。经实际生产验证:模具结构合理,生产的塑件达到使用要求。     

注射成型工艺参数对薄壁透明塑件熔接痕的影响

为解决薄壁透明塑件熔接痕问题,提出了一种局部加热的模具设计方式,利用工具显微镜和激光显微镜测量熔接痕的三维结构,研究了工艺参数(模具温度、熔体温度、注射压力)对熔接痕的影响。结果表明:提高模具温度、熔体温度和注射压力,都能使熔接痕的长度、宽度和深度有效减小;当形成熔接痕处的模具局部温度从55℃升高到80℃时,熔接痕的宽度减小了71.9%,深度减小了84.9%,有效提高了成型塑件的外观质量。     

基于Moldflow的汽车门板塑件模流分析

以某汽车门板塑件成型为例,运用Moldflow软件分析了汽车门板塑件的浇口位置和成型工艺,并对熔体填充过程进行模拟分析,对填充、保压、熔接痕、冷却效果、翘曲变形等进行了模拟分析,预测塑件注射成型的缺陷。基于模流分析的结果,设计合理的注射模结构,并用于指导生产,提高塑件成型质量。     

基于Moldflow的汽车保险杠浇注系统优化设计

以某汽车保险杠成型为例,用Moldflow软件模拟2种不同方案下塑件的注射成型过程,对比分析熔体流动填充状况、型腔注射压力分布、熔体流动前沿温度分布与塑件可能产生熔接痕、气穴、翘曲变形等模拟结果,找出了其中的较优方案,并用于指导生产,获得了高质量的塑件。     

大型塑件避免产生熔接痕的方法

介绍了汽车大型外观塑件的质量标准,分析了塑件熔接痕形成的原因。结合经验,给出了针对不同原因所导致熔接痕的改善对策。重点阐述了汽车大型塑件注射模调试过程中如何避免产生熔接痕的方法及修改模具型腔面的具体工艺。     

基于蒸汽模技术的平板电视面框外观质量研究

阐述了传统注射成型技术下,塑件会产生熔接痕、银丝纹等难以避免的缺陷,并分析了这些缺陷产生的原因,着重介绍蒸汽模技术在平板电视面框成型中的应用。     

车载蓝牙上盖高光无痕注射模设计

以车载蓝牙上盖为例,介绍了高光无痕注射模结构,重点阐述了模具中含随形介质通路的内部管道结构。注射成型实验证明,该结构类型的模具能有效消除或减轻熔接痕、流痕等缺陷,降低塑件表面粗糙度值,使塑件外表面达到高光效果。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。