机械零件毛坯轧制的进展及在我国应用的看法

机械零件毛坯轧制是制造机械零件的高效、经济的方法。文章介绍了用轧制方法轧制机械零件毛坯的工艺及其改进。     

入口侧辊板非对称接触轧制时的变形效应

针对中厚板轧制时前端部板形翘曲这一生产中常见的技术问题,在轧机上通过静态压缩、轧制试验,观察、分析了入口侧辊板非对称接触对轧制过程的影响.探讨了轧制时变形区几何形状系数l/对轧件前端部翘曲的影响规律.指出入口侧辊板非对称接触轧制时,金属沿高向变形与流动、应力分布呈非对称状态,使金属沿高向上的纵向流动不均匀,这是导致轧件出辊缝后前端部翘曲的主要因素之一.     

含铌微合金钢热连轧过程中组织演变及工艺参数的预测

采用有限元计算模型对热连轧生产过程中带钢断面温度场的分布进行了预测,建立了描述含铌微合金钢软化行为的再结晶模型及计算精轧过程应力-应变曲线的流变应力模型。在此基础上,对X46级管线钢工业轧制中的奥氏体再结晶动力学、微观组织演变及精轧的轧制力、轧制力矩、轧制功率进行了预测,结果与实测值吻合较好,反映了工业生产的实际。     

径轴向辗环机优化轧制规程的计算机辅助设计

此文介绍了利用数字计算机进行矩形截面环轧制的优化规程设计方法,优化是基于轧制过程的物理模型,考虑了各种轧制约束条件,结果符合实际生产情况,并且可使轧机容量得到充分利用,大大缩短轧制所需时间,节约材料与能源消耗。     

非对称交叉轧制压力研究与分析

对冷轧条件下非对称交叉轧制情况下变形区金属流动状态进行了分析 ,建立了总轧制压力计算公式 ,并用理论与实验两方面进一步分析了轧制压力与交叉角之间的关系。     

港口机械用大直径滑轮坯的轧制

介绍了大直径滑轮坯的轧制工艺 ,分析了轧制过程中存在的问题 ,并提出了解决方法。     

两种铜合金复合板带室温轧制成形工艺及结合机制的研究

研究了黄铜 /紫铜 ,黄铜 /白铜复合板带室温轧制成形工艺 ,借助金相显微镜、扫描电镜、电子探针分析了复合工艺参数对轧制复合后的复合板结构强度的影响 ,确定了最佳复合工艺 ,并对结合机制进行了探讨     

采用大变形弹塑性有限元法对带材异步冷轧过程的数值模拟

此文采用纠正的拉格朗日列式和基于弹塑性乘法分解的超弹性塑性本构关系,对铝带在不同轧制条件下的异步冷轧过程进行了大变形弹塑性有限元模拟.结果表明,在异步轧制时,轧制力对工作辊辊径的变化表现出非敏感性,而且由于搓轧区的存在,使得变形区内静水压力的绝对值比同步轧制时要小得多.     

方轧件在椭圆孔型中轧制温度场的三维有限元分析

应用MARC/autoforge有限元软件对方轧件在椭圆孔型中的轧制温度场进行了热力耦合模拟.研究了模拟过程中的传热边界条件,分析了轧制前和轧制过程中轧件中温度场的分布和变化规律.模拟计算结果和实验结果的比较说明二者基本是相符的.     

一种门窗五金件用冷轧窄带钢的轧制新工艺

详细介绍了一种用圆钢线材经处理 ,轧制、热处理、精轧成门窗五金件生产用圆盘窄带钢的新生产工艺和设备 ,以提高窄带钢轧制精度、表面质量 ,减少设备投资 ,同时介绍了国内外的应用情况。     

钢窗手柄冷楔横轧工艺

分析了楔横轧成形条件,以冷楔横轧钢窗手柄为例探讨了工艺方案选择和工艺参数确定.试轧获得基本成功.如用于实际生产尚须进一步提高加工精度.     

旋转尾翼火箭测试平台平衡滚速分析与弹道设计

目的分析旋转尾翼对火箭测试平台平衡滚速的影响,基于旋转尾翼式火箭测试平台开展飞行弹道设计。方法以旋转尾翼火箭测试平台为例,分析旋转尾翼、箭体和滚动轴承间的受力,建立旋转尾翼火箭测试平台箭体和尾翼滚转通道动力学模型,分析旋转尾翼不对称性、不同摩擦力系数时旋转尾翼对平台箭体平衡滚速的影响关系,并以倾斜有轨发射旋转尾翼火箭测试平台为例,开展弹道设计与仿真。结果采用旋转尾翼设计,当滚转等效舵偏较大时,能够降低固定尾翼平台平衡滚转。随着滚转等效舵偏的增加,箭体的平衡滚速不会持续增加,箭体的平衡滚转速度将稳定在4.4 rad/s左右。旋转尾翼轴承摩擦力系数显著影响旋转尾翼对箭体平衡滚速的抑制作用。经过弹道设计仿真,箭体的平衡滚速为4.01rad/s,满足试验载荷对转速的需求。结论旋转尾翼能够有效抑制箭体的平衡滚速,基准弹道设计满足飞行试验要求。     

Stability Analysis of Chatter on a Tandem Rolling Mill

Accurate prediction of the onset of chatter is difficult in designing and operating a rolling mill. Both the lack of precise rolling process models and analytical methods for the investigation of mill stability have forced designers and users to rely on experience and trial and error, which are time consuming and cost demanding. A comprehensive rolling process model is introduced to form the foundation of chatter analysis that includes a range of possible process variations. Analytical chatter models for both single and multiple-stand rolling mills are constructed that account for interactions between mill structure and rolling process, as well as between adjacent stands. Stability analysis is performed to formulate criteria for rolling mill design and operation. Finally, simulations and experiments are presented to verify some basic components of the rolling process model that constitute the proposed chatter models.     

车门框条滚压成形工艺及滚压线设计

以X110型车门为例,分析零件工艺性,介绍滚压成形工艺过程,强调在模具设计和制作中应注意的问题。设计由滚压、校正、滚焊和自动断料等工艺流程组成的滚压线,可作为类似滚压工艺参考。     

Design of Profile Ring Rolling by Backward Simulation Using Upper Bound Element Technique (UBET)

The upper bound element technique (UBET) is used to determine the optimum intermediate shape for profile ring rolling using backward simulation. The lowest energy rate is the key issue in achieving the optimal intermediate shape as well as the backward simulation of the process. The plastic flow of material in ring rolling is assumed to be a sequence of successive closed-die forging processes. The ring is divided into features, which provide an approximated profile consisting of a number of rectangular elements. The simulation of the profile ring rolling was tested with different profiles of rolls, and two such cases are presented here. The present method was validated using an experimental radial ring rolling mill designed and fabricated in the Dept. of Mechanical Engineering at Ohio University for the investigation of both cold and hot ring rolling processes. As the results show, this technique is capable of solving the backward simulation of profile ring rolling problems in a much shorter time compared to the finite element method (FEM), which cannot easily simulate profile ring rolling. Moreover, as an engineering tool, this approach can be applied effectively to the profile ring rolling process and can serve as a useful tool in industrial applications.     

The effect of cold rolling on the foaming efficiency of aluminium precursors

The objective of the present study is to investigate the role of cold rolling on the foaming ability (or foamability) of aluminium precursors, made by continuous rotary extrusion, a process performed at elevated temperature, starting by powder. For this purpose, the effect of different parameters including initial shape of precursors, rolling direction, amount of deformation in each rolling pass and final thickness of rolled specimens are experimentally investigated. Furthermore, the foaming efficiency of both rolled precursors and as-received extruded ones is compared. To clarify the role of secondary processing operations on the foaming efficiency, precursor samples are prepared following different forming and machining process chains, before the final foaming operation. Finally, hardness tests are performed on as-received precursors and rolled samples to notice the correlation between rolling parameters, state of strain, foaming efficiency and hardness. The results of the study show that: (a) cold rolling considerably improves foamability, (b) rectangular precursor bars have higher foaming efficiency than round ones, both before and after cold rolling. Besides, the improvement in foamability due to cold rolling is greater if precursors are rolled in the extrusion direction, rather than the orthogonal direction.