中厚板轧机微尺度静定化升级

摘要：中厚板轧机常因受到事故干扰而不能实现其高端轧制能力,其关键在于约0.3 mm的轧辊弯曲挠度和轧辊轴承座侧面与机架窗口立柱之间约1 mm间隙两个微尺度量的负面影响。依据机构学微尺度静定设计理论对中厚板轧机的微尺度静定化进行升级。辊系机构静定化设计包括取消原偏移距设置并采用智能衬板以实现轧制过程中四辊平行,防止四列短圆柱滚动轴承烧损、轧机颤振、板带镰刀弯和辊系叼板窜辊等弊端的同时还提高了轧机固有频率。中厚板轧机的机构学静定化升级,可充分释放轧机高端能力,实现大压下轧制新工艺并可生产高强度新品种板带,达到降本增效的目的。     

四辊板带轧机工作稳定性分析

现代化的四辊板带轧机由于在线换辊的需要,轴承座与机架间存在换辊间隙。虽然为了保证轧制稳定设置了工作辊相对支承辊的偏心距,但偏心距派生出的水平力仍使辊系处于不稳定的工作状态。本文在充分考虑附加弯矩和摩擦弯矩的影响后,通过对板带轧机轴承座与机架间有效间隙的分析,并结合辊系最佳偏移距的确定,提出了保证轧制稳定的措施,给出了相应的理论计算。     

基于有限元的六辊轧机机架变形分析

针对以往机架设计中窗口尺寸与轴承座的配合间隙缺乏理论依据,且未考虑轧机辊系侧向力对机架窗口变形的影响,通过对某厂六辊轧机辊系的稳定性计算,求得轧辊辊系的水平力;采用有限元方法对轧机机架在轧制力和辊系水平力共同作用下的变形进行分析。结果表明,辊系轴承座侧向力对机架窗口水平方向的变形有很大影响,只有考虑了侧向力的作用,才能精确计算出机架窗口的变形。     

铝箔轧机工作辊轴承座稳定性分析

用能量稳定法对 2 2 0 0mm高速铝箔轧机辊系中工作辊轴承座同机架窗口侧向有隙或无隙两种不同约束条件下的稳定性进行了分析。提出开闭复合运动副新概念 ,重新综合铝箔轧机轴承座约束机构 ,解决了该轧机工作辊轴承座与机架窗口间更换轧辊必留间隙和在运行时须消除间隙的矛盾。本概念及分析结果给出铝箔轧机实现高速轧制和工作辊止推轴承治烧延寿方法     

立式短应力线轧机轧辊轴向窜动原因分析及改进思路

分析了轧制长材用短应力线轧机轧辊轴向窜动的原因,指出承受轴向力的轴承选型及与轴承座孔、拉杆、球面垫的配合是其主要原因。对于立式轧机,由于上下辊系的偏移引起的平行四边形也是轧辊轴向窜动的主要原因,为此,提出了解决立式轧机出现平行四边形问题的方案。     

可逆式四辊轧机辊系稳定性分析

由于四辊轧机的工作辊、支撑辊与其轴承座之间以及轴承座与机架之间存在着间隙。在轧制过程中,工作辊、支撑辊及其轴承座如无固定的侧向力约束,将处于不稳定状态,这种不稳定将导致轧制不稳定及精度降低,加速轧辊的磨损及降低轴承的使用寿命。因此,应使工作辊和支撑辊在轧制时保     

液压轧机轧线标高调整方式

液压压上四辊薄板轧机,压上液压缸设置在下支承辊轴承座的下面。该类轧机轧制线标高通常以上工作辊下表面为基准面予以给定。当上辊系(上工作辊,上支承辊)用具有位移显示的调零机构(电动压下或斜楔机构)调到指定的位置(理想轧制线标高)后,轧制线标高也就确定了。实际生产中,轧辊都有一定的辊径使用范围,因此轧辊重磨后再装到轧机上,必定导致轧制线标高有所变动,为了稳定生产,允许轧制线标高有所变化,但范围是有限制的,一般给定一个轧制线标高最大变动量△_(max),允许轧制线在0～△_(max)之间变动与调整。     

轧机微尺度可控辊系研制

在笔者提出的轧机辊系微尺度行为可控理论框架下，经过对2200mm铝箔中轧机工作辊轴向力进行大量的在线测试，开发研制了2200mm铝箔中轧机微尺度可控辊系。该辊系具有工作辊和支承辊平行度调节、工作辊轴承座和机架窗口间安装间隙的控制、工作辊辊系空间自位、轴向力可视检测及热补偿等性能。在800-1550m／min不同轧制速度下的工业试验结果表明，通过微量调整工作辊相对支承辊的交叉角可以改变作用于工作辊的轴向力大小，甚至改变其作用方向，将轴向力控制在轴承寿命允许限度之内；显著增加工作辊轴承座固有频率以改善其振动特性，证实了微尺度可控辊系理论框架的正确性，为根治长期困扰2200mm铝箔中轧机工作辊止推轴承(双列角接触球轴承)短寿烧损和轧机被迫降速运行的病状奠定了理论基础。     

2200铝箔中轧机微尺度可控辊系机理试验

针对渤海铝业有限公司2200mm铝箔中轧机工作辊止推轴承短寿的问题，在2200mm铝箔中轧机现有辊系，进行十多次工作辊轴向力工况在线测试的基础上，开发研制丝杠千斤顶，安装于其轴承座和机架窗口之间，进行轴向力可控试验。结果表明，工作辊轴向力的大小通过微量调整同支承辊之间的交叉角大小可以减小或增大，甚至改变其作用方向。在总轴向力中所占比例最大的是轧辊交叉引起的初始轴向力分量和有隙轴承座水平振摆引起的波动轴向力分量，本试验可以将其控制为最小。证明笔者提出的轧机微尺度可探辊系理论是正确的，它为解决长期困扰渤海铝业有限公司2200铝箔中轧机工作辊止推（双列角接触球）轴承短寿烧损和被迫降速运行的问题奠定基础。     

四辊轧机轴向力研究

四辊轧机工作辊轴承及支承辊止推轴承失效的主要原因是轴向力过大.辊系各轴线不平行引起辊子间有轴向相对运动的趋势,在轧制压力作用下该轴向相对运动趋势使辊子间产生轴向静摩擦力,这就是产生轴向力的主要原因.通过调整机架窗口衬板和轧辊轴承座衬板,保持辊系各轴线的平行度,可显著降低轴向力,理论分析和实验结果一致.     

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.