锻造操作机旋转位置控制系统仿真研究

针对400 kN/800kN·m锻造操作机旋转控制系统的特点,通过MATLAB/Simulink和AMESim协同仿真技术对锻造操作机旋转液压伺服控制系统进行建模和仿真研究.仿真结果表明:基于模糊控制算法的控制系统可以自动适应锻造操作机的现场工作环境,动态输出PID控制器的各项调节参数,与基于普通PID算法的控制系统相...     

200kN锻造操作机系统压力异常的原因分析

国内某厂关键设备200 kN锻造操作机在使用过程中出现了油温升高过快的现象,经现场测试发现其系统压力出现了明显异常情况。针对此问题,分析了200 kN锻造操作机工作原理,通过理论计算方法确定了系统压力油走向,进一步研究找到了系统压力异常变化的原因。分析研究结果表明,密封圈损坏导致的缓冲缸内泄漏量增大是引起200 kN锻造操作机系统压力变化的根本原因,而密封圈损坏和缓冲缸密封型式选用不合理有着直接关系。     

100kN锻造操作机试制成功

100kN锻造操作机于1992年5月在太原重型机器厂试制成功,其主要技术性能达到了80年代初期世界先进水平。它的试制成功和采用,对发挥大型自由锻造水压机的能力,提高劳动生产率,减轻锻造工人的繁重体力劳动,提高锻件的质量等都将起到显著的作用,并为我国大型快锻油压机的开发奠定了基础。 100kN锻造操作机是太原重型器厂为宝鸡有色金属加工厂新开发的联动型锻造操作机,它是31.5MN锻造水压机的配套设备,用于钛合金的锻造生产,也可用于16MN、20MN自由锻水压机。能夹持100kN和100kN以下的锻件作翻转、升降、倾斜、侧摆、侧移、夹紧放松和进退七个     

基于AMESim的锻造操作机大车行走液压控制系统仿真研究

针对200 kN·m/500 kN·m锻造操作机大车行走电液比例控制系统的工作特性,利用Pro/E三维软件建立了操作机实体模型,得到较为精确的负载质量;利用AMESim仿真软件建立了大车行走液压控制系统的仿真模型,研究不同工况下操作机大车行走系统的动态特性;仿真结果为操作机大车行走液压控制系统的设计、调试提供参考.     

钳口凸齿对锻造操作机夹持过程影响的研究

分析了钳口凸齿对锻造操作机夹持力的影响,结果表明表面带凸齿的钳口夹持工件时比平钳口夹持工件更为省力和有效。通过对热工件受挤压时变形情况的分析,确定了热工件的屈服应力;对钳口夹紧工件时的工况进行模型简化和受力分析,得出了钳口表面带凸齿的锻造操作机夹持力计算方法;对300,400和800 kN锻造操作机进行了实例计算,计算结果证明了计算方法的有效性。     

1000kN/2500kNm锻造操作机吊挂装置仿真研究

基于动力学系统分析软件ADAMS,建立了1000kN/2500kNm锻造操作机吊挂装置的虚拟样机模型,分析了上升和倾斜运动时各部件的运动及受力情况。结果表明,钳杆最大平升高度、最大上倾和下倾角度、平升缸和倾斜缸静平衡驱动力均满足设计要求,仿真结果可以为锻造操作机的设计制造提供指导。     

锻造操作机近恒力输出夹持机构的传力比研究

针对被夹持锻件的典型类型,分析了锻造操作机夹持机构的性能要求,明确了夹持机构近恒力输出的必要性。根据锻造操作机夹持机构的结构特点,分析了夹持机构的传力比,确定了影响夹持机构传力比的关键因素,研究了夹持机构结构参数的确定思路。以锻造操作机夹持机构的最大回转半径为依据,结合夹持机构的结构参数,提出了一种能够实现近恒力输出的操作机夹持机构传力比的确定方法,为操作机近恒力输出夹持机构传力比的确定提供理论依据。以300 kN操作机夹持机构为例,验证了研究思路的可行性,并分析了提升夹持机构夹持性能的思路,为近恒力输出夹持机构的设计提供了参考。     

100kN锻造操作机

100kN锻造操作机于1992年5月在太原试制成功。该机主要技术性能达到了世界80年代初水平,能替代国内进口同类型产品。它的试制成功和采用,对发挥大型自由锻造水压机的能力,提高劳动生产率,减轻锻造工人的繁重体力劳动,提高锻件的质量等方面都将起到显     

平行连杆式锻造操作机缓冲装置的结构特性分析

根据平行连杆式锻造操作机的结构特性和控制原理，分析了锻造操作机吊挂系统的工况，明确了锻造操作机的缓冲机理，建立了锻造操作机的启动和制动工况动力学模型，为优化锻造操作机的缓冲性能提供了理论支撑。结合锻造操作机的缓冲机理和工况，分析了缓冲缸和平升缸对锻造操作机缓冲性能的影响，明确了平升缸在缓冲装置中的作用。通过对缓冲缸的受力状态和平升缸驱动力矩的分析，提出了影响锻造操作机缓冲性能的结构因素，研究了钳杆平升降与缓冲缸、平升缸与前转架的位置关系对缓冲性能的影响，确定了前吊杆和缓冲缸的结构参数，明确了锻造操作机缓冲装置关键结构因素的内在关系，为锻造操作机的动力学分析和吊挂系统结构设计提供了理论依据。     

200kN液压锻造操作机监控系统研究

针对200kN液压锻造操作机特性,采用模块化构造、结构化编程思想,建立了由工业控制计算机和可编程控制器组成的现场总线控制系统。下位机采用西门子S7-300可编程控制器实现操作机前进、后退、俯仰、旋转等一系列动作,上位机采用WinCC编程实现操作机的数据采集、监控和故障诊断等功能。通过实验和仿真对比证明:该系统响应速度快,位置控制准确,精度高,降低了系统复杂程度,提高了工作稳定性。     

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。