第10讲共挤塑模设计

介绍了各种塑料复合型材共挤模的结构设计：模外复合共挤模，模内复合共挤模，多层复合共挤模及可控型坯共挤模的设计方法。     

塑料异型材表面复合共挤模具的调试

塑料异型材表面彩色复合共挤在国内日益兴起 ,对该类挤出模具的调试是获得满意共挤出异型材的关键之一 ,现结合共挤模具 ,探讨了共挤工艺参数的设定、共挤层厚度的控制、共挤层表面质量的控制、共挤层与基材的粘结强度等共挤出模具的调试技术     

共挤双向拉深复合管材挤压模设计

介绍一种共挤双向拉深复合二层塑料管材挤压模结构,为了增强复合管材纵横向拉伸强度和物料的加工性能,对挤压模特点、物料的塑化及成型原理作了论述。结果表明:挤压模设计合理,与普通挤压模相比,具有物料塑化性能好,挤出稳定,管材纵横向强度高,表面质量好,制造成本低等特点。     

塑料异型材后共挤模具的设计

塑料异型材后共挤技术是一种新型的塑料异型材软硬复合共挤技术，越来越得到人们的重视和广泛应用，有广阔的应用前景。本文论述了塑料异型材后共挤模具的总体结构，技术设计要点以及在实际生产中的应用。     

多工位复合共挤挤出模头设计

介绍了国内外PVC-U复合共挤产品的现状及多工位复合共挤的定义,并阐述了多工位复合共挤挤出模头结构特点及设计的技术难点。通过对多工位复合共挤产品断面及多工位复合共挤模头结构的技术分析,确定了多工位复合共挤挤出模头的设计要素,以供类似专业技术人员参考。     

单机共挤复合棒材机头设计

设计了单机共挤复合棒材机头,介绍了单机共挤复合棒材机头的工作原理及结构、口模成型段尺寸的确定和内、外螺杆分流板的设计。该机头设计合理、结构紧凑,能很好地完成复合棒材的挤出成型。     

铜,铝与钢冷轧固相复合的粘合机制

近年来,多层金属材料的应用日益广泛。用冷轧固相复合法生产复合板带材,因具有产品粘合可靠、表面质量好、便于成卷连续自动化生产等优点,更得到迅速地发展。但是,目前冷轧复合技术只适用于生产宽度不大的产品。为进一步扩大其应用范围,生产宽度更大的多层金属复合材料,必须开拓新的轧制工艺技术,以求在以下两方面得到进展:     

精密冷挤零件的复合热处理工艺

齿轮精密冷挤是 90年代初国外开始大量应用的先进齿轮加工工艺。与传统的工艺相比 ,它具有精度高、工序简单、工件表面光洁度高等优点。对小模数齿轮及薄壁齿圈等零件 ,可以使全部工序冷挤成型 ,不但替代了齿部的切削加工 ,而且具有很高的生产效率和较低的生产成本。某合资厂生产的洗衣机的制动轮 ,为碗形内齿轮零件 ,零件简图如图 1所示。它是由低碳钢 ( 0 0 8%～ 0 1 0 %Ｃ)精密冷挤加工成型 ,经表面硬化处理后 ,不再进行机加工。图 1　制动轮零件简图外方对制动轮表面硬化处理技术要求 :表面硬度 >550ＨＶ ,硬化层深度 0 3ｍｍ ,硬化…     

钒铬复合渗的研究

应用光学显微镜、显微硬度计、扫描电镜、电子探针和Ｘ射线衍射仪研究了Ｔ１０、４５、３Ｃｒ２Ｗ８Ｖ、９ＳｉＣｒ和ＧＣｒ１５钢在固体渗钒后，再进行盐浴渗铬的复合渗层的组织结构和性能。结果表明，钒铬复合渗层的厚度显著高于单渗钒层与钒铬共渗层。复合渗层具有高硬度、高耐磨性、高耐蚀性和抗高温氧化性等优良的综合性能，并可通过调整工艺改变复合渗层中渗钒层与渗铬层硬度的比例，来满足工件不同使用性能的要求。     

酒钢高速线材棒材复合生产线改造后工艺特点

本改造方案是在保证酒钢原一高速线材生产产品的基础上,利用现有厂房、起重运输设备、钢坯上料加热设备、部分轧钢设备及公用辅助设施,在线材生产线上增加一条高速直条棒材生产线,使原生产线形成一条既具有线材生产能力、又具有棒材生产能力的复合生产线。     

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。