一种挤压半空心铝型材的遮盖式一模双孔分流模的结构

提出了一种针对半空心铝型材采用遮盖式一模双孔的挤压模结构。通过实际例子,详细介绍了这种模具结构有关参数的选择。主要包括挤压机能力的选择,模孔布置、分流孔设计、下模焊合室结构和工作带的选择。介绍了模具强度的校核方法。将传统的平面模、单孔分流模与这种新的遮盖式双孔模的实际挤压结果进行了对比。这种新的模具结构简单、容易加工。实践表明,采用这种新的一模双孔挤压模结构可显著提高模具的寿命、提高铝型材生产效率和降低成本,所得型材尺寸精度高、表面光亮,是一种值得推广的的模具结构。     

半空心铝型材保护导流式分流模结构

介绍了半空心铝型材挤压模的研究现状,分析了针对半空心铝型材的5种模具结构,包括整体式平模、镶嵌式分流模、遮盖式分流模、吊挂式分流模和切割式分流模。提出了一种新的半空心铝型材挤压的保护导流式分流模具结构,结合具体实例,介绍了这种保护导流式挤压模结构,详细分析了这种结构的组成和参数选择,主要包括分流孔的设计、挤压机能力的选择、分流桥的结构、应力间隙和工作带的选择,并给出了模具强度校核方法。根据挤压结果,与传统平面模、切割式分流模进行了对比。结果表明,这种新型模具结构简单、便于加工,可显著提高模具强度和寿命。     

一种半空心铝型材一模四孔保护式分流模结构

介绍了一种针对半空心铝型材的一模四孔保护式挤压模结构。详细描述了这种新的结构的有关参数的确定,主要包括模具结构的组成、分流孔的设计、下模焊合室结构与工作带的选择等。新的结构打破了传统的由二件组成的结构,而采用了由三件组成的形式。介绍了模具强度的校核方法。并根据挤压结果,对传统的普通分流模、单孔切割式分流模、一模双孔切割式分流模和新的一模四孔保护式分流模结构进行了比较。这种新的一模四孔分流模结构具有结构简单、便于加工的特点。实践表明,这种挤压半空心型材新的一模四孔分流模结构,可以大幅度提高挤压机的挤压生产效率,并可显著提高模具的寿命,挤压的铝型材尺寸精度高,表面光亮,是一种值得推广的结构。     

一种半空心铝型材嵌入保护式分流模结构

提出了一种针对半空心铝型材挤压的嵌入保护式分流模结构。这种结构是由三件组成的分流模,有别于传统的二件式结构。介绍了这种新的模具结构组成要素,主要是在上模和下模都设计了假的模芯。详细描述了这种结构有关参数的选择,包括上模结构、分流孔设计、配合间隙的确定、下模模芯尺寸的确定以及焊合室与工作带的选择等。并对三种模具的挤压结果进行了比较。结果表明:这种三件组合镶嵌式保护式分流模结构具有明显优势,可以大大提高模具的寿命,是一种值得复制推广的模具结构。     

一种保护式一模双孔分流模结构

对一模多孔挤压模深入研究和开发,提出了一种针对半空心型材一模双孔保护式挤压模结构。通过常见的实际例子,详细描述了这种结构有关参数的选择与优化方法,主要包括模孔的布置、分流孔的设计、模芯的结构、下模焊合室和工作带的选择。介绍了模具强度的校核方法。结果表明,这种新的一模双孔挤压模结构是有效的,可以提高生产效率、降低成本。     

半空心铝型材一模双孔导流式挤压模结构

针对半空心铝型材的挤压生产,提出一种一模双孔导流式挤压模结构。结合实例介绍了这种结构模具的有关参数的选择与优化方法。主要包括分流孔的设计、分流桥的结构和工作带的选择。提出了模具强度的校核方法。根据挤压生产结果,将这种新的双孔模结构与传统的平面模、单孔分流模进行了对比。该模具具有结构简单、容易加工的特点。使用结果表明,这种一模双孔导流式挤压模结构,能有效地提高生产效率、降低成本,是值得推广的。     

内外上模镶嵌三件式分流挤压模

当前新能源电动汽车发展迅猛，水冷式电动机是其核心部件之一。电动机外壳材料采用的是铝合金挤压型材，这种型材在生产中容易出现诸如内孔椭圆及壁厚差异大等形状与尺寸精度不达标的问题。解决这些问题的关键是模具。通过分析水冷式铝合金电动机外壳的结构特征及传统的模具现状，针对上述问题提出了一种内外上模镶嵌三件式分流挤压模，其主要部件包括分流板、上模和下模，而与传统分流模不同的是上模由一个外上模和一个内上模镶嵌组成。介绍了这种新型模具的组成以及主要部件的结构参数选择。采用分流板可以合理调配金属流量和降低挤压力。采用内、外上模镶嵌结构形式可以解决制造精度低及制造误差积累大的问题，使模具具有互换性，并且可节约材料和缩短加工周期。设计应力空间则可以保护内上模，解决壁厚严重不均的问题。实践表明，这种新型模具解决了传统模具在挤压时出现的问题，是一种值得复制和推广的新型模具。     

半空心铝型材挤压模的设计

半空心铝型材是很常见的铝材,这些型材的挤压模具的主要问题是模具强度不够。分别介绍了为保证半空心型材挤压模具的强度而设计的几种模具结构,它们是一体式整体平面模、遮盖式分流模、遮盖式导流模、碰穿式分流模与整体式分流模。在生产实践中,可以根据半空心型材的结构特点与质量要求来选择与之相适应的模具结构。     

一种半空心铝型材一模双孔保护式分流模结构

提出了一种针对半空心铝型材的一模双孔保护式挤压模结构。通过实例介绍这种模具结构的有关参数的选择与优化方法。主要包括模孔的布置、分流孔的设计、模芯的结构、下模焊合室和工作带的选择。介绍了模具强度的校核方法。这种新的一模双孔挤压模结构是有效的,可以提高生产效率、降低成本,值得推广。     

半空心铝型材一模四孔切割式分流模

介绍了一种半空心铝型材一模四孔分流模结构。为了保证模具的强度,采用分割式分流模结构,改变了传统的分流模的结构组成,增设了前置分流板。详细介绍了一模四孔分流模结构的参数选择,主要包括挤压机能力、模孔的布置、分流孔的设计、下模焊合室和工作带等。根据挤压结果,对普通的分流模和一模四孔分流模结构进行了对比。实践表明,这种针对半空心型材的一模四孔分流模具可以大幅提高挤压机的效率和降低生产成本。     

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).     

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.     

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.     

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。