数控冲床振动分析及缓冲系统研究

通过理论推导和振动测试,分析冲床缓冲系统的减振器刚度大小和刚度特性对设备基础及机身振动的影响,提出综合考虑基础振动的减小和机身振幅增大的减振器刚度确定方法;介绍一种具有硬-软-硬变刚度特性的碟形弹簧减振器的开发,一个减振器有4个减振柱,采用C型碟形弹簧,弹簧组合采用多组对合且各组叠合片数逐渐增加。与同类减振器相比,该减振器能量吸收率高,振动缓冲效果好。     

T30数控转塔冲床的优化设计

采用有限元方法对T30数控转塔冲床机身的强度、刚度和自身模态做了计算分析,在此基础上,对机身进行了优化设计.优化机身比原机身节约材料20％左右,在有效降低生产成本的同时,也为冲床的合理设计提供了借鉴.     

数控转塔冲床减振降噪技术的研究

运用数值仿真方法对数控转塔冲床进行了动力学分析,并采取了机身结构优化设计、模具弹簧参数优选和静音冲裁模式等三种减振降噪措施。对改进前后机床的振动和噪声进行了测试和对比,测试结果表明减振降噪效果明显。本文能够为数控转塔冲床的新产品研发及技术改进提供参考。     

阻尼调节阀预紧力对液压减振器特性影响的试验研究

分析不同阻尼调节阀结构参数对液压减振器性能的影响,并以某型抗蛇行液压减振器为研究对象,在不改变液压减振器其他性能影响因素的基础上,通过试验研究阻尼调节阀的弹簧预紧力对液压减振器的性能影响。试验结果表明:阻尼调节阀弹簧预紧力仅影响阻尼调节阀开启后的液压减振器性能;开阀后拉伸动刚度随预紧力的增加而增加,压缩动刚度不受预紧力影响;拉伸及压缩阻尼系数均随弹簧预紧力增加而增加。     

结晶器振动板弹簧导向支承的分析和计算

连铸机结晶器振动愈来愈多的采用液压振动,振动的导向广泛地采用板弹簧结构.本文对板弹簧导向结构的设计参数进行了分析计算,得出了板弹簧导向支承的挠度曲线方程和刚度计算公式,并结合某板坯连铸机结晶器液压振动板弹簧导向支承的设计,根据振幅的大小求出了板弹簧的变形力和刚度.     

肘杆式数控转塔冲床机身有限元分析与优化

运用COSMOS有限元软件对新开发的肘杆式数控冲床的机身进行有限元分析与计算,研究其在公称力下机身的变形和应力分布情况,并分析构成机身结构主要部件对机身应力应变的影响。根据分析结果,对机身结构进行了优化设计,在保证机身刚度的情况下,进一步减轻机身重量,降低生产成本,提高了产品的竞争力。     

摩擦铆压用交流伺服塑性连接设备结构可靠性研究

为了提高低塑性轻量化板材接头的连接质量、降低成形力、避免连接过程中产生裂纹缺陷,提出了摩擦铆压塑性连接工艺,并设计了交流伺服塑性连接设备.利用ANSYS Workbench软件对设备的机身进行了静力学分析,校核了机身刚度和强度,并通过模态分析研究了设备振动响应特性.结果表明:该设备每个自由度的运动均由单独的交流伺服电机...     

粉末液压成形设备框架机身的有限元分析与结构改进

针对2 000kN数控精密金属粉末液压成形设备的框架机身进行了结构分析和优化设计,对框架机身的简化模型进行静、动态有限元计算.在静态分析中对其进行强度校核和刚度校核,通过模态分析给出了机身振动的固有频率及相应振型.在此基础上,采取结构改进措施,降低了设备机身的制造成本,保证了设备性能.     

基于ADAMS的数控转塔冲床模具弹簧设计与仿真

模具弹簧对数控转塔冲床的冲裁频率、主传动功耗、振动和噪声等方面均存在影响,本文运用多体动力学软件ADAMS对模具及弹簧系统的动作原理及动力学特性进行了研究,可为模具弹簧设计及优化提供理论依据,对数控转塔冲床加工频率的提升以及减振降噪具有指导意义。     

锻锤弹性基础动态特性的仿真

根据模锻锤弹性基础的特点,建立了系统的动力学模型.采用高精度及高数值稳定性的RKF(Runge-Kutta-Felhberg)算法对模型进行了求解;对不同激励条件、不同弹簧刚度和阻尼条件下砧座及混凝土基础的振动情况进行了仿真;讨论了弹簧刚度、阻尼器阻尼系数和混凝土质量等参数对隔振效果的影响.为弹性基础的设计提供了依据.     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.