The Numerical Simulation on Hollow Part's Precise Sizing Process With Cross-wedge Rolling

The hollow parts formed with cross-wedge rolling (CWR) have a wide application in many fields, such as architecture and automobile, etc. But the finished configuration of part’s cross section was always ellipse and it was hard to make it satisfied with traditional forming process. This paper proposed a FEM model of hollow workpiece of CWR in the sizing process, and simulated the deformation condition using the ANSYS program. Three kinds of parts with different wall thickness were calculated. Some stress and strain fields of the deformed hollow parts at various conditions are gained. The influence of wall thickness on the distribution of stress and strain was analyzed. The paper also found two phenomena, which never have been seen at traditional experiment, and author tried to give some explanations. The ANSYS program provided the relationship between the tolerance of the deformed workpiece and the deforming parameter. It is helpful to design the sizing dies of a new precise forming process of hollow parts on the CWR. The new process that designed through the information of FEM improved the accuracy of hollow parts on CWR. It proved the validity and practicability of numerical simulation.

Research on the Error Averaging Effect in A Rolling Guide Pair

By studying the e ects of geometric precision on kinematic accuracy, an error mapping model has been established, based on the hypothesis that a motion pair and its installation surface are rigid. However, when using this assumption,there is a significant error induced in high-precision computer numerical control(CNC) machine tools as compared with reality. One of the most important reasons for this error is failing to consider the error averaging e ect of motion pair elements. Therefore, this work examines a high-precision horizontal machining center as its research object, and analyzes the error averaging mechanism of a rolling guide pair under a deformation of the rolling elements. The carriage bearing forces caused by guideway straightness errors are obtained by constructing a geometric error model of a single carriage. The relationship between guideway straightness errors and carriage bearing forces is described by a transfer function in the spatial frequency domain, and its characteristics are analyzed. It quantifies the so-called error averaging e ect of the rolling guide system and, on this basis, a static model for four carriages is established to reflect the error averaging e ect of the rolling guide pair on the position and orientation errors of the motion pair. In addition, it is found that the wavelengths and phase di erences of guideway errors a ect this error averaging mechanism, but the amplitude and preload have little influence thereon. The experiment result shows that the kinematic straightness errors in the x-and y-directions were approximately 1/3 to 1/2 of the guideway straightness errors in the corresponding directions. The results can be used to guide the precision design and assembly of machine tools.

Soft measurement model of ring's dimensions for vertical hot ring rolling process using neural networks optimized by genetic algorithm

Vertical hot ring rolling(VHRR) process has the characteristics of nonlinearity,time-variation and being susceptible to disturbance.Furthermore,the ring's growth is quite fast within a short time,and the rolled ring's position is asymmetrical.All of these cause that the ring's dimensions cannot be measured directly.Through analyzing the relationships among the dimensions of ring blanks,the positions of rolls and the ring's inner and outer diameter,the soft measurement model of ring's dimensions is established based on the radial basis function neural network(RBFNN).A mass of data samples are obtained from VHRR finite element(FE) simulations to train and test the soft measurement NN model,and the model's structure parameters are deduced and optimized by genetic algorithm(GA).Finally,the soft measurement system of ring's dimensions is established and validated by the VHRR experiments.The ring's dimensions were measured artificially and calculated by the soft measurement NN model.The results show that the calculation values of GA-RBFNN model are close to the artificial measurement data.In addition,the calculation accuracy of GA-RBFNN model is higher than that of RBFNN model.The research results suggest that the soft measurement NN model has high precision and flexibility.The research can provide practical methods and theoretical guidance for the accurate measurement of VHRR process.

TIN_DDM Buffer Surface Construction Algorithm Based on Rolling Ball Acceleration Optimization Model

In view of the TIN_DDM buffer surface existing in the construction and application of special data type,algorithm efficiency and precision are not matching;the paper applied the rolling ball model in the process of TIN_DDM buffer surface construction.Based on the precision limitation analysis of rolling ball model,the overall precision control method of rolling ball model has been established.Considering the efficiency requirement of TIN_DDM buffer surface construction,the influence principle of key sampling points and rolling ball radius to TIN_DDM buffer surface construction efficiency has been elaborated,and the rule of identifying key sampling points has also been designed.Afterwards,by erecting the numerical relationship between key sampling points and rolling ball radius,a TIN_DDM buffer surface construction algorithm based on rolling ball acceleration optimization model has been brought forward.The time complexity of the algorithm is O(n).The experiments show that the algorithm could realize the TIN_DDM buffer surface construction with high efficiency,and the algorithm precision is controlled with in 2σ.

Welch功率谱与卷积神经网络结合的滚动轴承故障诊断

针对滚动轴承故障诊断在小训练样本下和强噪声下无法取得高精度识别的问题,提出一种基于Welch功率谱结合卷积神经网络进行诊断的方法。该方法以原始时域振动信号作为输入,用Welch功率谱转换数据形态同时对高强度噪声进行抑制,再用得到的功率谱训练卷积神经网络,最后将训练好的模型用于轴承的故障诊断。与WDCNN[1]等方法进行对比,实验发现在混合负载下,该方法平均识别率正确达到99%,其它方法达到这个精度至少需要20倍以上的训练样本量,明显优于WDCNN等方法。抗噪实验结果表明噪声对信号的干扰越强烈,该方法的抗噪表现越好,其抗噪性能要显著优于WDCNN等方法。

风电轴承大尺寸钢球光球加工技术

针对国内现有风电轴承大尺寸钢球光球机加工精度低,加工效率低的问题,对钢球在光球机动、静磨盘沟道内的运动规律、受力特点和磨削机理进行分析,光球时钢球受到的磨削力与动、静磨盘沟道深度比有关,并基于ADAMS仿真得到最佳动、静磨盘沟道深度比为7∶3,去两极和环带、成形、走圆工序最佳动磨盘转速分别为90,120,90 r/min。样机试验结果表明,改进后光球机的光球效率提高了30%,球形误差至少提高了0.2 mm,表面粗糙度Ra值至少减小了0.03 mm。

GH2132高温合金本构模型及大断面收缩率楔横轧成形研究

采用Gleeble-3800热模拟试验机对GH2132高温合金进行等温恒应变速率压缩实验,获取该合金在变形温度900~1100℃、应变速率0.01~10 s^(-1)范围内的真应力-应变曲线。对所得流动应力曲线进行摩擦与绝热修正,以消除试样热变形过程的绝热温升效应以及和砧子与试样间接触摩擦作用对实验结果的影响后,建立了考虑应变补偿的Arrhenius型本构模型。误差分析结果表明,其相对平均绝对误差不超过7%,可用于该合金高温变形行为研究。分析了具有大断面收缩率特征的GH2132合金楔横轧轧件的成形过程模拟,进一步验证了所建本构模型的准确性,为GH2132高温合金楔横轧工艺开发奠定了基础。

高速精密数控轧辊磨床中心架液压润滑系统的设计及其优化

中心架作为轧辊磨床的重要部分之一,起着支承和卸荷的重要作用。文中以某型高速精密数控轧辊磨床为依据,设计了其中心架的液压润滑系统,基于AMESim软件建立该液压润滑系统模型并进行仿真计算,分析得出侧瓦和底瓦静压固定活塞直径、静压固定活塞杆径及调速阀设定流量对系统中静压腔油压特性具有显著影响。采用遗传算法对影响系统静压腔油压特性的3个参数进行优化,结果表明:优化后的中心架液压润滑系统中,静压腔油压稳定性得到了显著的改善,达到稳定状态的时间明显缩短,验证了优化方案的合理性,其结果可为轧辊磨床液压润滑系统的设计及优化研究提供理论依据。

超声滚挤压执行器的机床精密调高装置研究

为解决超声滚挤压装置在超声加工时,由于执行刀具在机床垂直高度方向上,挤压头总是无法与工件中心轴线处于同一水平线,导致加工准备工作耗时长、高度调节难的问题,文章提出一种既能满足超声滚挤压执行器高度调节而且使用时不受机床局限的精密调高装置的机械设计方法。利用蜗轮蜗杆机构,实现高度方向调节,同时由楔块承重,可以承受在刀架夹紧情况下的巨大载荷,保护内部零件、螺母和弹簧片稳固构件,确保该装置在作业时避免出现移动,增加稳定性。最后通过试验对比得出:利用该装置后滚压头的调高时间缩短到30 s以内,测得工件粗糙度降低了7%左右,直径偏差降低了50%~67%。满足超声加工时在不同工况下,对刀具高度调节实现精准把控,极大程度地解决了超声滚挤压执行器在不同机床工作时高度调节的需求。

高速线材精轧锥辊箱故障诊断分析

针对某钢厂高速线材产线精轧区域锥辊箱振动问题,通过在线监测系统及时定位锥辊箱缺陷位置,准确判断劣化程度。对锥辊箱振动全过程进行了分析总结,并对在以后的振动分析时遇到类似的振动信号应考虑的问题提出一定见解。

基于时域卷积网络的精轧出口厚度预测

以精轧过程为研究对象,引入时域卷积网络算法,构建了基于时域卷积网络的精轧出口厚度预测模型。利用时域卷积网络模型提取精轧过程时序数据的特征信息,通过优化模型结构和参数,提升精轧出口厚度预测性能。实际钢种数据集仿真实验结果表明,相较于传统方法,本文所提出的时域卷积网络算法在均方根误差、平均绝对百分比误差及决定系数等评价指标方面存在较大优势,可为现场工程师提供重要的决策信息。

我国斜轧管生产装备及工艺技术的发展

介绍了我国斜轧管机组包括圆盘轧管机组、精密轧管机组和三辊轧管机组的引进和国内自主设计制造情况;分析了斜轧管机组在迭代发展过程中的改进和创新以及存在的不足;探讨了斜轧管机组装备及工艺技术未来的发展趋势。指出斜轧管机组具有产品壁厚精度高、生产组织灵活、产量适中、投资少,适合于小批量多品种生产的优点,特别是三辊轧管机组在生产中厚壁管品种方面的优势是其他的机组所不可替代的。建议未来要结合轧管新技术、新工艺以及采用智能建造技术,对现有斜轧管机组进行升级改造,并结合自身的优势在专业化品种研发上下功夫。

精轧设备精度管理与维护优化实践分析

本文聚焦于精轧设备精度管理与维护优化这一主题,旨在深入剖析其理论基础、实践策略及优化路径,以期为提升精轧设备性能、保障产品质量、提高生产效率、延长设备寿命及实现安全生产提供科学依据与实用指导。首先,通过对精轧设备工作原理与结构特性的深入剖析,明确了影响设备精度的关键因素。其次,针对精轧设备关键部件,如轧辊、轴承、传动系统的精度检测技术与方法进行了详细介绍,构建了一套涵盖绝对精度、重复精度、稳定性等多维度的精度评估指标体系。在实践策略层面,分别探讨了设备选型与采购、安装调试、运行维护以及技术改造与升级各阶段的精度管理要点。在精轧设备维护优化方面,本文倡导由预防性维护向预测性维护的转变,利用大数据、AI等先进技术进行故障预测,以降低非计划停机风险。

精轧螺纹吊底平台在大体积高桩墩台中的应用与创新

从工程实际出发,对墩台施工水上作业平台工艺进行对比分析,介绍精轧螺纹吊底平台的工艺特点、原理、流程及操作要点。结合全直桩基墩台结构特点,对桩基与上部结构连接方式的设计进行创新,在钢管桩外侧设置4块扇形钢板,并围焊成环形,与精轧螺纹吊底平台共同形成一种新型组合支承结构,提高吊底和底模的周转率,加快工程进度,确保大体积高桩墩台施工的安全和质量,经济和技术效益明显。可为类似墩台施工、钢管桩与上部结构连接方式设计提供参考。

Energy Optimization of the Fin/Rudder Roll Stabilization System Based on the Multi-objective Genetic Algorithm （MOGA）

Energy optimization is one of the key problems for ship roll reduction systems in the last decade. According to the nonlinear characteristics of ship motion, the four degrees of freedom nonlinear model of Fin/Rudder roll stabilization can be established. This paper analyzes energy consumption caused by overcoming the resistance and the yaw, which is added to the fin/rudder roll stabilization system as new performance index. In order to achieve the purpose of the roll reduction, ship course keeping and energy optimization, the self-tuning PID controller based on the multi-objective genetic algorithm （MOGA） method is used to optimize performance index. In addition, random weight coefficient is adopted to build a multi-objective genetic algorithm optimization model. The objective function is improved so that the objective function can be normalized to a constant level. Simulation results showed that the control method based on MOGA, compared with the traditional control method, not only improves the efficiency of roll stabilization and yaw control precision, but also optimizes the energy of the system. The proposed methodology can get a better performance at different sea states.

Machining characteristics of complex prism pattern on electroplated roll by copper

The BLU (back light unit) is the core component of the LCD for notebook, mobile-phone, navigation, as well as large sized TV, PID (public information display), etc. In order to enhance optical efficiency of LCD, optical films with the uniform prism patterns have been used for BLU by stacking two films up orthogonally. In this case, light interference-phenomenon occurred such as Morie, wet-out, u-turning, etc. It caused several problems such as low brightness, spots and stripes in LCD. Recently, the high-luminance micro complex prism patterns are actively studied to avoid the light interference-phenomenon and enhance the optical efficiency. In this study, the roll master to manufacture complex micro prism pattern film was machined by using the high precision lathe. The machined patterns on the roll master were 50, 45, 40, 35, 30, 25, 20, 15, 10 and 5 μm in the pitch with 25.0, 22.5, 20.0, 17.5, 15.0, 12.5, 10.0, 7.5, 5.0 and 2.5 μm in the peak height, respectively. The roll was 2 000 mm in length and 320 mm in diameter. The electroplated roll by copper and the natural single crystal diamond tool was used for machining the patterns. The cutting force was measured and analyzed for each cutting condition by using the dynamometer. The chips and the surfaces after being machined were analyzed by SEM and microscope.

A Robust Roll Stabilization Controller with Aerodynamic Disturbance and Actuator Failure Consideration

Combining adaptive theory with an advanced second-order sliding mode control algorithm,a roll stabilization controller with aerodynamic disturbance and actuator failure consideration for spinning flight vehicles is proposed in this paper.The presented controller is summarized as an“observer-controller”system.More specifically,an adaptive secondorder sliding mode observer is presented to select the proper design parameters and estimate the knowledge of aerodynamic disturbance and actuator failure,while the proposed roll stabilization control scheme can drive both roll angle and rotation rate smoothly converge to the desired value.Theoretical analysis and numerical simulation results demonstrate the effectiveness of the proposed controller.

辊环开槽专用金刚石砂轮精密成形修整研究

分析了钢厂硬质合金辊环开槽的金刚石砂轮成型修整的各种方法,设计及开发了金属结合剂金刚石砂轮电火花成形修整机床,改进与创新了专用脉冲电源,讨论了精密成形修整中的关键要素,提出一种以大电流加工来解决高效修整、配备叠加包络高压方波,应对难修的特殊配方。新的电火花磨削工艺是采用粗加工的大电流、狭脉宽、高频率,成倍地提高生产率,用中、精加工规准确保精密成形,解决了小R半圆加工后两侧偏“瘦”的工艺问题,最后用磨成的辊环槽型精度完成对成形砂轮精度的认证。

轴承外圈滚道直径变动量测量与分选装置

针对目前轴承外圈滚道直径变动量测量效率与测量精度无法兼顾的问题,通过双通道自动送料机构、双工位自动夹取机构、双通道自动分选机构、综合检具快速测量机构的设计实现双工位运行,提升了装置的运行与测量效率(与手动测量相比效率提升约1倍);以高精密电感位移传感器为核心构建测量系统,实现了轴承外圈滚道直径变动量的高精度测量;以FX三菱PLC为主控核心设计控制系统架构,通过YKHMI编制人机界面,使装置运行具备良好的稳定性和可操作性。设计试验条件,采集测量数据并进行测量结果不确定度评估,结果表明:该装置的扩展不确定度为5.40μm,满足滚道车削半精加工后直径变动量的测量精度要求。

螺杆转子齿形台阶的横轧精确成形

螺杆压缩机具有工作效率高、易实现高转速等优点,被广泛应用于空气压缩机、热泵等行业.螺杆转子是螺杆压缩机的关键零件,它具有复杂的螺旋齿形台阶,制造难度大.该螺旋齿形台阶的传统制造工艺为:先对圆钢进行铣削加工,后经过磨削最终成形.铣削时,需要去除大量的多余金属,生产效率低,材料利用率也低.针对这一难题,提出了采用横轧精确成形齿形台阶的新工艺,具有生产效率高、材料利用率高、机加工量小等优点.本研究采用数值模拟和实验研究相结合的方法,揭示了横轧齿形台阶的成形机理,分析了不同成形阶段的应力和应变分布规律,讨论了轧制过程中轧制力的变化,最后对实验件进行了精度分析,结果显示实际成形件的截面轮廓与设计轮廓吻合良好,所有测量点的误差在-0.71~1.2 mm,成形精度高,采用横轧进行螺杆转子齿形台阶的精确成形是可行的.