HC六辊冷轧机垂扭耦合振动分析

轧机系统异常耦合振动是影响轧件质量的重要因素。通过对某钢厂2180型六辊冷轧机的现场测试及分析发现工作辊的异常振动会传递到主传动系统中,造成齿轮箱等部件的故障,万向接轴并未有效隔断振动的传递。根据实际参数建立了包含主传动系统扭转振动和工作辊垂直振动的轧机耦合振动数学模型,并求解了模型的响应特性。同时,通过仿真分析发现了轧机垂扭耦合振动的真实性。定量分析发现系统发生耦合振动时工作辊扭转角及振动位移变化相对较大,扭转振动对垂直振动的影响较为明显。此方法为抑制轧机系统振动、减少设备故障提供了理论依据。     

F2轧机工作辊耦合振动分析

轧机工作辊的稳定运行是保持轧制过程稳定,保证轧件质量的重要前提。实践证明,工作辊处振动复杂,并且存在耦合现象。根据实际工况,综合考虑轧辊偏移、液压压下系统、轧制工艺等因素建立了轧机工作辊3种属性的耦合振动模型。利用MATLAB求解了该模型的固有频率及不同轧制工艺参数下系统振动响应情况,得到了不同轧制参数对轧制过程的影响及各属性振动的相互影响关系。通过对某钢厂F2轧机实测信号的分析,验证了结论的正确性。此研究为抑制轧机振动、实现轧制工艺参数最优化提供了依据。     

CVC冷轧机工作辊垂直-水平耦合振动分析

轧机系统异常振动是影响轧件质量的主要因素。不同属性的振动共同促使了轧机系统的整体振动,辊系的垂直振动和工作辊的水平振动是较为主要的振动。根据某钢厂CVC轧机实际参数建立了轧机垂直-水平振动的动力学耦合模型并进行了求解,得到了变参数下轧机振动响应情况,通过提取钢厂轧机在线振动监测系统数据分析验证了仿真的正确性。结果显示,轧制工作辊处存在耦合振动情况,轧机系统振动特性与各种轧制工艺参数有关,对工艺参数进行适当调整可以有效地减小轧机振动。     

冷轧机轧制过程中轧辊垂振的研究

以冷轧机系统的垂振为研究对象,结合近年来冷轧机垂振问题的研究成果,得出冷轧机垂直振动的振源在辊缝.冷轧机在高速轧制时,辊缝润滑状态发生变化导致辊缝阻尼改变,从而引起轧机的垂直振动.建立了冷轧机简化模型,并对冷轧机轧制过程进行仿真,分析了辊缝阻尼与轧机垂直振动之间的关系,得出辊缝阻尼变小导致轧机的垂直振动.通过增大辊缝间的摩擦系数和增设阻尼设备的方法维持合适的辊缝阻尼,可消除轧辊的垂直振动,保证轧机平稳运转.     

四辊轧机辊系刚柔耦合动力学建模研究

板带轧机的工作稳定性取决于系统的动力学特性,其中轧辊沿轴线方向的弯曲变形运动是影响板带厚度和表面质量的主要因素。几种运动形式相互影响、耦合作用,令轧机辊系成为一个复杂多变量动态系统。为综合考虑轧制过程中轧辊不同振动形式之间的耦合效应,同时考虑工作辊动特性与轧制外载荷动态增量之间的相互作用关系,本文分别建立了辊系刚柔耦合动力学模型、轧机系统刚性振动耦合动力学模型和轧制变形区耦合动力学模型。通过建立的四辊轧机刚柔耦合动力学模型体系,对轧制过程进行动态控制,仿真分析了轧制过程中轧机辊系和变形区内轧件的动力学特性。     

大型液压轧机轧制薄板异常振动及振纹研究

对F3轧机异常振动信号及薄板振纹进行了研究,结果表明F3轧机主传动轴发生扭振,其固有频率为20.5Hz。由薄板振纹反演出轧机工作辊的振动频率为51Hz,此频率与工作辊水平振动的基频相吻合。通过倒频谱分析,得出50Hz附近的边频是由F3工作辊转频调制而成。     

四辊轧机垂直振动特性研究及测试分析

为研究四辊轧机系统的垂直振动特性,考虑到四辊轧机具有较复杂的振动过程,建立了四辊轧机非对称6自由度垂直振动模型,利用机械振动学牛顿第二定律理论,构建四辊轧机的垂直振动系统动力学方程。采用Matlab软件对四辊轧机6自由度系统垂直振动模型的固有特性进行理论计算,对系统各阶固有频率及其相应的主振型进行分析,得到了第5阶固有频率是引起四辊轧机强烈自激振动的主要频率。通过现场垂直振动测试平台的验证,表明了该系统垂直振动模型具有较高精度的优点。以上研究结果为研究四辊轧机的现代动态设计、动力学分析以及抑振减振等问题提供了一定的理论基础。     

基于Adams的冷轧机工作辊振动分析与仿真

随着对冷轧机振动研究的不断深入,发现冷轧机工作辊所呈现的振动通常都是耦合振动。首先建立冷轧机主传动系统和冷轧机辊系的简化振动模型,并利用Matlab软件计算出冷轧机主传动系统和辊系振动模型的固有频率。然后利用Adams软件对冷轧机辊系进行动力学仿真,并在仿真过程中添加3倍振频的扰动力和扰动力矩。仿真结果表明:在无外界干扰情况下,由于轧辊间存在的摩擦力,该冷轧机会发生自激振动;对于六辊冷轧机,中间辊的水平振动也会影响工作辊的垂直振动和扭转振动;当垂直振动和扭转振动同时发生时,轧机工作辊每种振动会显示其他振动的特征。     

考虑间隙时粗轧机主传动扭振分析

粗轧机主传动的主轴联轴器由于运行磨损和频繁换辊形成间隙,该间隙在咬钢过程中的启闭会引起系统咬钢冲击,导致主传动较大幅度的扭振。探讨了考虑间隙因素时粗轧机主传动的扭振分析方法,并基于龙格-库塔方法建立了粗轧机主传动扭振仿真模型,对粗轧机主传动的扭振响应进行数值仿真,求出扭矩放大系数。最后通过实例分析验证了模型的合理性。     

冷连轧机辊系非线性耦合振动特性分析

考虑冷连轧机辊系振动时,垂直和水平两个方向的轧制力相互影响且处于动态变化,因此引入了动态轧制力这一概念。同时,考虑到轧机辊系间的非线性阻尼、非线性刚度以及外激励,建立了冷连轧机辊系非线性耦合振动模型。利用多尺度法求解了耦合振动系统的幅频响应,研究结果表明,非线性高次项刚度和外激励对轧机耦合系统的振幅影响明显,均出现了两个共振区域,且伴随着跳跃现象。进一步运用奇异性理论得到了系统的静态分岔方程,发现可以通过改变开折参数来预测和控制非线性耦合系统的动力学行为。最后,运用非线性理论分析并验证了系统的混沌特性,给出了发生混沌行为的临界点,从而减小和避免轧机辊系非线性耦合系统发生共振。     

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.     

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.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

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Antimony Induced Crystallization of Amorphous Silicon

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.     

A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING

Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.