海洋平台桩腿齿条精密氧气切割工艺试验研究

桩腿齿条是自升式钻井平台升降系统的核心零部件,其加工成形质量直接影响到自升式钻井平台的制造。桩腿齿条的加工,在国际上均采用数控火焰切割机完成,一次成形达到设计要求,且切割断面质量较高,产品直接投入使用,不再进行机械加工,可提高生产效率。目前国内对自升式钻井平台桩腿齿条的需求主要依赖进口,供货周期长、价格昂贵,限制了海洋平台的制造。文中针对CJ46,JU2000两种主流型号桩腿齿条,通过对齿条钢板材料、设计参数及制造标准,结合工艺要求对齿条成形所需的切割工装设备条件以及工艺参数进行探讨,并结合1:1试验件的切割工艺试验研究,形成桩腿齿条的精密氧气切割工艺,为桩腿齿条的自主生产奠定基础。     

衬套类零件压铸模抽芯结构分析及其液压抽芯设计

通过对衬套类零件压铸模斜滑块抽芯、斜导柱抽芯、齿轮齿条抽芯、液压抽芯结构对比分析，提出液压抽芯可实现此类模具设计的通用化和系列化，并对液压抽芯设计做了进一步阐述。     

液压削匀机的常见故障及解决方法

削匀加工是皮革加工过程的一个主要工序,如果处理不好,会严重影响加工质量.本文以常用的现代制革设备系列液压削匀机为例,从液压削匀机的液压系统和该机经常出现的故障两方面分析了皮革加工质量的影响因素.并介绍了相应的解决方法.     

万能铣床对长齿条的加工

介绍了在万能铣床上加工长齿条的方法，克服了无专用加工设备的困难，并保证了产品的加工质量，降低了生产成本，效果良好。     

工件翻转装置液压传动系统设计

工件翻转装置是自动化生产线的重要组成部分,其设计的好坏直接影响整个自动化生产线的工作水平.设计工件翻转装置的机械结构,利用齿轮齿条传动结合液压传动系统实现工件的翻转;设计工件翻转装置的液压传动系统并分析其工作原理.结果表明:利用液压传动系统控制机械装置的运动,可以很好地实现工件的翻转.该液压翻转装置具有结构简单、输出力大、惯性小以及易于控制等优点,与电气控制、可编程控制器和计算机控制等结合,可组成各式自动化机械,在自动化生产中具有广阔的应用前景.     

两自由度摇摆台耦合动力学建模与仿真

考虑两自由度摇摆台内、外平台的耦合效应以及负载偏心造成的偏载力矩对驱动系统的影响,采用齐次变换方法建立了两自由度摇摆台的动力学模型。驱动系统采用齿轮齿条液压缸,考虑齿条间隙、液压流量非线性等影响,对液压伺服系统进行了仿真分析。仿真结果为驱动、控制系统的设计提供了参考依据。     

21吨齿条推钢机齿条的焊接

21吨齿条推钢机上的齿条(加工刨齿后)净重2300公斤,材质为45号铜钢,加工后齿面硬度170～210H_B,要求齿条上下表面不平行度不得大干0. 2公厘。由于我厂铸造及热处理技术和设备条件上的限制,要求将齿条分为甲乙二段铸造,再分别进行热处理,然后用焊接的方法将两部分焊接在一起(见图1)。齿条制造总的工艺过程是:铸造,退火,粗加工(包括刨接口处的焊缝坡口,见图2),淬火及回火(回火后     

转阀式液压助力转向系统建模与仿真分析

考虑了汽车液压助力转向器中的机械子系统与液压子系统,建立了相应的数学模型并利用Matlab/Simulink控制系统仿真软件建立了汽车液压助力转向系统的仿真模型.仿真分析了活塞有效面积、扭杆刚度和系统供油流量的变化对系统响应的影响情况,结果表明:增加系统供油流量、减小扭杆刚度都会使转向器的助力油压增大,此时齿条的位移将增大从而使稳定时间延长;活塞有效面积的大小几乎不影响助力油压的大小,齿条助力将随活塞有效面积成正比例变化.     

某钢管喷标设备的改造设计

钢管喷标设备是近年来生产企业为了适应国际化要求、满足用户需求、提升产品形象而投入的设备.由于是新设备,其质量等级参差不齐.为此,对原有设备存在的问题进行了分析,对立柱、导向机构、升降机构和驱动装置等主要零部件进行了重新设计与加工,采用双立柱结构使得设备刚性增大,稳定性增强;齿轮齿条传动加线性滑轨导向的移动装置运行平稳,可靠性增强;双导向轴的升降装置使得升降灵活,效率高.使用结果表明改造后的设备完全符合工艺要求.     

载重汽车液压挡土装置传动机构优化

对重型自卸车车厢顶盖液压启闭装置的扇形轮驱动机构、链条驱动机构、液压杠杆通过法兰盘连接齿条驱动机构、车厢顶盖单侧反转机构和液压缸体上安装齿条驱动机构的工作原理和性能进行比较分析。结果表明:不论是在空间安排上还是在稳定性上,液压缸体上安装齿条驱动机构都具有前几种系统不能比拟的优势,值得推广。     

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。