环件轧制原理和设计方法

分析了环件轧制变形特点，提出了环件轧制咬入、锻透和弯曲力学模型，建立了环件轧制咬入条件、锻透条件和刚度条件，阐明了环件轧制原理。基于环件轧制原理，建立了环件轧制技术设计方法，导出了轧制用毛坯。孔型和轧制进给参数设计计算公式。根据环件轧制试验结果，对其咬入条件和锻透条件进行了验证。     

环件径轴向轧制过程锥辊旋转运动学分析

稳定轧制是环件径轴向轧制过程保证产品质量的重要条件之一.文中基于几何关系和运动学原理,对环件径轴向轧制过程中锥辊与环件接触区旋转运动进行了研究,结果表明:轴向锥辊在与环件接触面处的旋转线速度尽量保持一致非常关键,轧制过程中应尽可能地保证锥辊锥顶点位于环件的圆心处.锥辊转速大于环件转速时,应增大径向孔型中的轧制力矩,使环件重新稳定;锥辊转速小于环件转速时,会导致轧制无法正常进行,出现环件位置严重偏移或卡环等现象.     

大型复杂环件缩比轧制成形的实验与模拟研究

研究了大型复杂环件形状因素和轧制速率对成形性能的影响规律。以缩比环件轧制实验和有限元数值模拟为基础，研究材料轴向转移模式及其变形机理，提出包含环件形状因素的成形性能评定方法。在此基础上，选用工业纯铅和LD10锻铝合金进行缩比环件轧制实验，得到了与数值模拟一致的结果，证实了所提出的包含环件形状因素的成形性能评定方法的可行性。同时发现，轧制速率影响环件轧制的成形性能，较大的轧制速率有利于环件轮廓填充。     

内台阶锥形环件轧制三维有限元模拟和工艺优化设计

以Abaqus三维有限元模拟软件为平台，对内台阶锥形环件的轧制过程进行了数值模拟，通过模拟计算揭示了内台阶锥形环件轧制缺陷的形成机理。根据轧制难度分析和有限元模拟结果，对轧制毛坯尺寸和轧制孔型进行了优化。采用铅环件试样在D51—160轧环机上进行了内台阶锥形环件的轧制试验，轧制了合格的内台阶锥形环件。模拟和试验结果表明，轧制毛坯尺寸和轧制孔型优化方案是合理的，基于变形模拟的轧环工艺优化方法是有效的。     

立式轧环机轧制中环件运动学规律

提出在轧制过程中环件中心不在芯辊和驱动辊中心连线上的轧制几何模型，并基于此模型导出环件中心位移、速度、加速度、环件转动惯量及转速和转动加速度的计算公式，建立了环件的运动学参数与环件壁厚和轧制进给量之间的关系，为环件轧制过程的在线测量和控制提供理论依据。     

风电轴承环成形缺陷数值模拟与工艺优化

风电轴承环属于大型异形环状零件,环件轧制技术是目前成形该类零件的主要方法。环件轧制过程中金属流动复杂,轧制孔型与环件之间接触情况复杂,同时由于轧制用毛坯、轧制工艺参数等原因,导致轧制过程中出现多种缺陷,缺陷的出现降低了环件质量,甚至使零件报废。该文针对风电轴承环轧制过程中出现的直径不扩大、椭圆度缺陷,运用Deform 3D软件对0134090003p6轴承成形过程进行模拟,提出当环件轧制到一定尺寸时,改用胀形工艺成形,获得了精度较高的环件,该工艺具有一定工程实用价值。并运用正交试验设计,发现影响胀形环件综合性能的主要因素是胀形坯料的尺寸形状,同时得到了该工艺的近似最优参数组合。采用粒子群优化算法优化相应的SVR参数,用训练好的SVR模型对胀形结果进行预测,得到一个可以预测环件胀形性能的SVR模型,该模型对工程实践有较好的辅助价值。     

基于空间啮合理论的环件轧制孔型设计

分析了环件轧制变形的啮合运动性质,基于空间啮合理论建立了环件轧制孔型的一般设计方法,并进行了实例设计计算。本文解决了复杂形状环件轧制孔型设计理论问题,对于环件轧制技术的应用和发展具有实际意义。     

基于空间啮合理论的环件轧制轧型设计

分析了环件轧制变形的啮合运动性质,基于空间啮合理论建立了环件轧制孔型的一般设计方法,并进行了实例设计计算。本文解决了复杂形状环件轧制孔型设计理论问题,对于环件轧制技术的应用和发展具有实际意义。     

环轧设定模型的自适应与自学习

在对环件轧制过程控制水平的论述与分析基础上,提出环件轧制过程的自适应与自学习控制结构,并针对过程控制中难以精确预报的轧制力与轧制力矩等重要参数,提出自适应与自调整算法并对一实际轧制过程验证所给模型与算法的正确性与可行性。     

轧环机进给速度设计

环件轧制是轴承、齿轮、法兰、轮箍等环形零件或毛坯的重要生产工序,在机械、汽车、航空等工业中得到了广泛应用。环件轧制原理如图所示,驱动辊同时作旋转轧制运动和直线进给运动,芯辊和导向辊为轴线固定的空转辊,可通过接触摩擦随环件一起转动;轧制时由于驱动辊的作用,环件不断地咬入驱动辊与芯辊构成的轧制孔型或辊缝,产生壁厚减小直径扩大的塑性变形,最终成为具有一定壁厚和直径的环件制品。环件轧制中,轧辊     

A new mathematical model for predicting the diameter expansion of flat ring in radial–axial ring rolling

An accurate prediction for the diameter expansion is quite essential for the ring rolling with large diameter since it determines the compatibility between the work rolls and the deformed ring in kinematics, so that the rolling stability and the final forming quality of the ring are influenced. A new mathematical model for predicting the diameter expansion of the flat ring in the radial–axial rolling process has been proposed, in which the variation of cross section, the particularity of initial rolling phase, and the effect of slip are all taken into consideration. Based on the proposed mathematical model, a 3D-FEM model for the radial–axial ring rolling process has been developed, and the corresponding experimentation has also been carried out. The diameter expansion in the simulation shows a good agreement with that in the experimentation. The forming quality comparison concerning the circularity, coaxiality, and tilting of the rolled ring has been executed between the former and new proposed method. The result indicates that the new mathematical method is very helpful to control the forming stability and hence improve the ring rolling quality significantly.     

精密冷轧环机工艺动力学模型

采用交流伺服电机和机械驱动进给系统的冷轧环机,其进给伺服控制系统的设计需要一个新的工艺动力学模型。给出了交流永磁同步伺服电机的数学模型,建立了机械传动机构的等效动力学模型,分析了环件冷辗扩的运动学和变形力学条件,得到了整个进给系统的工艺动力学模型。模型表达了伺服电动机电流、转矩、转速与轧制载荷、芯辊进给速度和位置,以及环件几何尺寸之间的动态关系,各变量之间存在非线性和耦合。模型已用于冷轧环工艺控制器的设计。     

环件轧制的热刚塑性耦合有限元分析

提出了一种适用于稳态轧制过程的热刚塑性耦合有限元方法，并依此对环件轧制过程进行了三维分析。结果表明，该方法能较精确地反映出环件轧制中各物理量变化规律。因此，为实现环件轧制过程的ＣＡＤ／ＣＡＭ奠定了基础。     

Complete modeling and parameter optimization for virtual ring rolling

Virtual manufacturing, usually consisting of complete modeling and optimization, of a manufacturing process has recently become one of the research trends in the area of process designing and selection. With the aim to realize complete modeling of a ring rolling process, a complex actuation mechanism model of a heavy radial-axial ring rolling machine has been established in this study. Moreover, a self-modified computer program for controlling the real-time movements of two guide rollers and two conical rollers in a ring rolling process has been developed. An optimization objective function has been proposed for saving the rolling time, in which the slip rate is regarded as the state variable. With this function, the virtual ring rolling process for producing a titanium alloy ring with a rectangular section has been successfully conducted using the finite element method. The simulation results are in good agreement with the experimental findings. Thus, the feasibility of the proposed method has been demonstrated. The computational result also reveals that the proposed optimization method can reduce the rolling time by about 28%.     

Towards a steady forming condition for radial-axial ring rolling

Radial-axial ring rolling (RARR) is a typical incremental forming process with high flexibility. It is difficult but essential to establish a successful RARR process and remain its stability by properly designing process variables. This paper is an attempt to develop a steady forming condition under which the RARR process can be established successfully and then proceeds stably with qualified ring rolled parts. For remaining process stability by alleviating dynamic contacts and collisions between the ring and the rolls, constant growth velocity condition (CGVC) of the ring is proposed as a design objective of the process variables. Then a mathematical model of the steady forming condition for RARR is developed based on the CGVC. The model describes both the mathematic correlations and the reasonable ranges of key process variables of RARR, and the application and role of the model are illustrated by a case study in detail. For verifying the steady forming condition for RARR, FE simulations and analyses are carried out through developing reliable 3D-FE models for the entire RARR processes under ABAQUS/Explicit platform. The simulation results show that the designed processes based on the mathematical model of the steady forming condition are successfully operated and have good stability. A value of the growth velocity of the ring, which is close to the median of its reasonable range determined by the steady forming condition, is recommended for the design of the process by taking into account the geometry of the rolled ring, material plastic deformation behavior of the ring and process stability.     

Modeling of on-line measurement for rolling the rings with blank size errors in vertical hot ring rolling process

The size errors of the ring blanks have a considerable effect on the vertical hot ring rolling process and the ring products’ dimensional precision. In this paper, the geometric relationship between the ring’s outer diameter and the measuring roll’s displacement is studied, and then, the influence of the blank size errors on this geometric relationship is analyzed. Subsequently, a modeling method of the measurement model for vertical hot ring rolling process is proposed, that is, the ring’s outer diameter can be measured indirectly through the relations of the ring’s outer diameter with respect to the measuring roll’s displacement and the ring blank’s outer diameter. Using this modeling method, the on-line measurement model of a certain type of vertical hot ring rolling mill was established, and the verification experiments were also conducted. The experiments showed that this on-line measurement model could calculate the ring’s outer diameter precisely, and the absolute errors of the formed rings were less than ±1.5 mm. The research results of this paper have general significance for the on-line measurement and process control of vertical hot ring rolling process.     

带锥度环形件的轧制研究

轧环属于特种锻造。轧制带锥度环形件较为复杂。由于存在初始轧制阶段不稳定性即随着轧制速度的提高,坯料容易向芯轴上部窜动。当坯料碰到主轧辊上部台阶时,坯料上部金属受损,使得轧制失败。针对带锥度环形锻件在初始轧制阶段不稳定性问题,建立了力学模型并进行分析,找出其原因,提出了保持轧制稳定的力学平衡条件,并列出其方程式。设计了相应解决方案。该方案在生产中取得了效果。     

循环统计量方法在滚动轴承故障诊断中的应用

为了处理滚动轴承故障振动信号中的调制现象，利用循环统计理论，分析了二阶统计量循环自相关函数和循环谱密度的特性。基于故障调幅信号模型推导出循环自相关函数的解调原理，指出调幅信号各成分在循环谱密度中的分布频段，提出在循环频率域中提取调幅信号的调制源的方法。该原理和方法通过仿真信号进行验证，应用于滚动轴承的内、外圈及滚动体的故障诊断，有效地提取出故障特征频率。     

Technology and experiments of 42CrMo bearing ring forming based on casting ring blank

Bearing ring is the crucial component of bearing. With regard to such problems as material waste, low efficiency and high energy consumption in current process of producing large bearing ring, a new process named ＂casting-rolling compound forming technology＂ is researched by taking the typical 42CrMo slew bearing as object. Through theoretical analysis, the design criteria of the main casting-rolling forming parameters are put forward at first. Then the constitutive relationship model of as-cast 42CrMo steel and its mathematical model of dynamic recrystallization are obtained according to the results of the hot compression experiment. By a coupled thermal-mechanical finite element model for radial-axial rolling of bearing ring, the fraction of dynamic recrystallization is calculated and recrystallized grains size are predicated. Meanwhile, the effects of the initial rolling temperature and feed rate of idle roll on material microstructure evolution are analyzed. Finally, the industrial rolling experiment is designed and performed, based on the simulation results. In addition, mechanical and metallographic tests are conducted on rolled bearing ring to get the mechanical parameters and metallographic structure. The experimental data and results show that the mechanical properties of bearing ring produced by casting-rolling compound forming technology are up to industrial standard, and a qualified bearing ring can be successfully formed by employing this new technology. Through the study, a process of forming large bearing ring directly by using casting ring blank is obtained, which could provide an effective theoretical guidance for manufacturing large ring parts. It also has an edge in saving material, lowering energy and improving efficiency.