The Development of Ring Rolling Technology – Part 2: Investigation of Process Behaviour and Production Equipment

This is the continuation of a thorough survey of work on ring rolling published in the English and German languages up to 2004 [see No. 2/3, p.111‐120]: The methods used to investigate the process are reviewed, separated into experimental and theoretical categories; the insights gained from these investigations are organised according to the challenges identified at the outset; developments in the control and operation of the process are described. Having given a set of ideal targets for the process, the state of current knowledge about ring rolling is assessed in order to predict likely developments: process modelling capability is nearly able to predict rolling behaviour for a complete cycle with sufficient accuracy to allow effective use of models for design of rolling schedules and preforms; analysis of material behaviour is relatively mature for steel rings, but has scope for significant extension for titanium and aluminium alloys and composites; design choices that seek to extend the flexibility of the process have had some exploration, but could be extended.     

Blank design optimisation for T-section ring rolling

Abstract

A T-section ring can be considered to consist of two rectangular section rings joined together, which can be described as an outer ring and an inner ring. As this is a complex shape, it is difficult to process a T-section ring by rolling, and a good design of blank is necessary. In this paper, four blank designs and rolling process were studied using finite element analysis. One was a rectangular cross-section, the other three were T-section but with varying flange rim volumes. In the three designs there is a volume flow from the outer ring to the inner ring during rolling, which is disadvantageous to good shape formation. One design had no material flow from outer to inner ring resulting in good ring shape. This had an initial blank design where the volume of metal in each of the two 'part' rings were equal to that of the final ring, respectively.     

Simulation of the behaviour of voids in steel plates during hot rolling

The prime objective of the work is to predict the behaviour of voids in the steel slab during hot rolling and to assess the tendency of the void to closure, depending on the process parameters. The rigid-plastic thermal-mechanical finite-element program is used for the purpose. The model which simulates the general case of deformation of a single void in a matrix undergoing plastic deformation is developed. This model allows the investigation of the influence of the stress state on the void's behaviour. Finite element calculations carried out for the industrial hot plate rolling process supply information regarding the stress state during rolling depending on the process technological parameters. These data are used as boundary conditions in the void's closure model and, in consequence, allow the analysis of the influence of rolling technology on the void's behaviour.     

Some aspects of development of models for automatic control of rolling mills

Computer-aided rolling-technology design is presented in the paper. Program is based on the solution of the set of non-linear equations which describe the process. They include continuity equations and power balance equations for continuous rolling. Reverse rolling is described by constant-rolling-force equations and power-balance equations for both main drive and reel drives. Typical results of calculations for hot and cold rolling processes are presented.     

带钢热连轧工艺设计软件的开发

为满足带钢热连轧工艺设计和生产管理的需要,采用Microsoft Visual Basic 6.0开发了带钢热连轧设定及组织性能预报软件。该软件设置了温度,粗、精轧道次,轧辊凸度设定模块,以及电机校核和晶粒尺寸预报模块,具有功能完善、人机接口友好、使用方便、计算精度高、适用范围广等优点,可用于带钢热连轧工艺设计、设备选型和现场生产管理。     

高颈法兰封闭轧制毛坯设计及工艺参数优化

基于环形件轧制理论以及轧制过程中金属体积不变规律,确定了高颈法兰封闭轧制毛坯的设计原则以及工艺参数的极限范围.通过有限元仿真模拟了高颈法兰封闭轧制成形过程,研究了工艺参数对轧制产品质量以及力能参数的影响规律,并确定了本文所研究高颈法兰的最优工艺参数.在D51-450型轧环机上采用自行设计的模具进行了轧制试验,并将试验结果与有限元模拟结果进行对比分析,验证了仿真结果的可靠性.     

贵冶闪速炉优化控制系统的应用实践与发展

文章简要叙述了最近一次对江西铜业集团公司贵溪冶炼厂1#闪速炉计算机优化控制系统进行的更新改造情况。重点描述了在该系统更新改造实施过程中优化设计、创新思考和应用扩充等方面的问题,并且对其今后的发展方向进行了展望。     

THE TECHNICAL AND ECONOMIC ADVANTAGES OF POWDER-FORGED PRODUCTS

Abstract

“Powder forging” is a hybrid process in which preforms made by conventional PM techniques are hot forged in closed impression dies. The process combines many of the best features of both conventionally made PM parts and hot forgings. Although the process is still in the development stages, indications are that “powder-forged” components can be produced having mechanical and physical properties equivalent to conventionally wrought steels, together with the complexity and dimensional accuracy normally associated with sintered parts.

The process appears an attractive and economic manufacturing route for many components for the following reasons: Material utilization is better than in conventional forging; detail and tolerances obtainable can lead to the elimination of much, if not all, finish machining; tight weight tolerances are possible in the “as-forged” condition, which on components such as connecting rods might ultimately lead to the elimination of weight-balancing operations.

The paper describes the features of the powder-forging process, and the production route is briefly outlined. Weight and machining savings are illustrated by reference to actual components made by G.K.N. Forgings Ltd. Forging load/preform density relationships are briefly mentioned, and the importance of preform design and forging-tool design emphasized. The main factors covering preform design are outlined.

Examples of mechanical properties obtained on powder-forged material are quoted, and it is explained that provided powder purity is controlled these can be comparable to those of conventionally wrought steels. The economics of the process is briefly discussed, and future development possibilities mentioned.     

Lorentz force infiltration of fibrous preforms

A new process for the production of metal matrix composites, whereby molten metal is forced into the interstices of a fibrous preform using electromagnetic body forces, is presented. These forces are created by subjecting the molten matrix to a concentrated transient magnetic field which, in turn, induces intense eddy currents in the melt. This gives rise to Lorentz forces which propel the metal into the preform. Equations governing the mechanics of Lorentz force infiltration of an axisymmetric preform surrounded by molten metal are solved numerically. A finite difference algorithm is applied to solve Maxwell's equation of electromagnetic field propagation and to determine the flux density as a function of radial position. The resulting Lorentz force is then calculated and balanced with the inertial, fluid friction and capillary forces, taking preform compression into account, to predict infiltration velocity and cumulative infiltration distance. Apparatuses were designed and constructed to infiltrate cylindrical preforms of 24 vol pct 3-μm-diameter chopped alumina fiber preforms with commercial purity aluminum. Two capacitor banks were charged from 1 to 4 kV and rapidly discharged to produce magnetic pulses of up to 4 tesla peak, at frequencies of 2 to 3 kHz in the infiltrating furnace. A commercial MAGNEFORM unit was also used to produce fields of up to 5 tesla at 5.6 kHz.-Sound composite samples were produced, to a depth of 1.8 mm into the preforms, with little or no breakage of fibers. Good agreement between theoretical model predictions and experimentally measured infiltration depths was demonstrated. Primary process variables for a given matrix-preform system, were the number of discharges, the magnetic pulse intensity and frequency, and the melt ring thickness. The model predicts a pulse frequency below which infiltration does not occur and an optimum frequency for maximum infiltration depth. Successive pulses are predicted to produce only slightly decreasing increments in infiltration depth with the parameters explored, indicating that the process allows greater infiltration depths than were attained with preforms and apparatuses used in this work.     

Developments in the Production of Galvannealed Steel for Automotive

The state of knowledge of formation of the galvanneal coating on continuous process lines is reviewed. Influences of materials and process variables on phase makeup that are key to achieving acceptability are reviewed. Current targets for key process variables are then described, followed by a consideration of the most frequent galvanneal coating quality issues and their causes. New developments in roll texturing for temper rolling of galvanneal are then described.     

高端轴承制造组织性能的近净冷轧环工艺调控

以高速机床主轴承、航空发动机轴承为代表的高端轴承,常在极端严苛工况下服役,对寿命和可靠性的要求极高,需要其轴承环件承载区具有十分优良的力学性能保障。近净冷轧环成形方法作为轴承环的先进技术,不仅具有显著的节能、节材、高效等技术经济效果,而且通过冷塑性变形强化能够大幅改善轴承环件性能,已成为轴承环国际主流的成形技术。从冷轧成形工艺过程组织演变、冷轧成形对热处理的影响规律以及冷轧形变-热处理相变协同调控3个方面的研究进展进行简要阐述,并就轴承环近净冷轧环工艺的研究技术难点进行了总结与展望。     

Motor maps, seizures, and behaviour.

Atypically organised motor maps have been described in some people with epilepsy and we have modelled this in rats. Our goal is to more fully understand the mechanisms responsible for seizure-induced functional brain reorganisation and to reverse their effects. Here we present an overview of the relationship between neocortical motor maps, seizures, and interictal behaviour. To begin we summarise the observations of atypical motor maps with epilepsy and in animal models following experimentally induced seizures. Our novel experiments have established that motor map expansion is linked to a functional alteration of motor behaviour. Evidence for some of the putative brain mechanisms responsible for motor map size is discussed. Our successes reversing seizure-induced map expansion by two different methods are also briefly reviewed. Lastly, unanswered questions for possible future experimentation are posed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

国内热轧H型钢工艺特点

简述了国内H型钢的发展现状,通过列举国内典型H型钢生产线,介绍分析了轧制H型钢的1—3—1、1-3和连轧三种工艺布置,以及目前轧制H型钢的X-X和X-H两种方法。根据目前国内生产状况,提出了H型钢技术改进的几项措施。     

Sintered Fe08%C10%Si04%Cu P/M Steel Preform Behaviour During Cold Upsetting

Cold upsetting experiments were carried out on sintered Fe 0.8%C1.0%Si-0. 4%Cu steel preforms in order to evaluate their deformation characteristics. Powder preforms of 86 % of theoretical density, with two different ratios of height to diameter, were prepared using a suitable die set assembly on a 1.0 MN capacity hydraulic testing machine. Sintering was carried out in an electric muffle furnace for 1.5 h at 1 150 ℃. Each sintered compact was subjected to incremental loading of 0.04 MN under dry friction condition till a crack appeared at the free surfaces. The experimental results were critically analysed, the stress as a function of strain and densification was obtained, then the work hardening behaviour was analyzed. It has been found that in the process of enhancing densification, strength and strain hardening is also induced during upsetting, but the work hardening behaviour is not homogenously enhanced against strain and densification.     

Synthesis and properties of Cu–Al–Ni shape memory alloy strips prepared via hot densification rolling of powder preforms

Abstract

Cu–Al–Ni shape memory alloy strips were successfully prepared by a powder metallurgy route consisting of preparing powder preforms from premixed Cu, Al and Ni powders by cold compaction, stepwise sintering in the range 873–1273 K, followed by unsheathed multipass hot rolling at 1273 K in protective atmosphere. The densification behaviour of the sintered powder preforms during hot rolling has been discussed. Homogenisation of the hot rolled strips was carried out at 1173 K for 4 h. It has been shown that the finished Cu–Al–Ni alloy strip consisted of self-accommodated plates ofβ' and γ' martensites together with a small amount of nanocrystalline Cu₉Al₄ phase. The finished hot rolled Cu–Al–Ni strips had fracture strength of 476 MPa, coupled with 2·5% elongation. The shape memory tests showed almost 100% recovery after 10 thermomechanical cycles in the hot rolled strips at 1 and 2% applied prestrain.     

线、棒材轧机主轧线物料跟踪功能分析

结合我院所做的几条线、棒材轧机生产线的情况，介绍线、棒材轧机主轧线通过热金属检测器、活套扫描器、咬钢信号等设备和信号进行物料跟踪控制功能的原理和过程以及模拟轧制功能。     

Simulation of the Forming Behaviour of a Boron Modified P91 Ferritic Steel

The forming behaviour at high temperature of a modified 9%Cr‐1%Mo (P91) ferritic steel containing B and Ti for elevated temperature service was investigated. The microstructure of the as‐received material is mainly martensite at room temperature, but special etching revealed prior austenite grains of about 25 μm in size. Torsion tests were conducted at temperatures in the range 850 to 1250 °C to simulate the hot rolling process under comparable conditions of temperature, strain rate and strain. The deformation data obtained from these tests were correlated with the Garofalo equation with a stress exponent of 4.6 and an activation energy of 315 kJ/mol. This equation was used to predict the formability behaviour for the rolling process and also to determine the maximum forming efficiency and stability of the steel. A temperature of 1200 °C is recommended to conduct the forming process.     

冷轧控制模型中摩擦因数模型的开发与应用

摩擦因数模型是冷轧的核心工艺模型之一,目前对其进行的大量研究多是在试验环境下进行的。基于经典摩擦因数模型的工艺原理,综合考虑了轧辊粗糙度、轧制速度等关键因素的影响,结合生产控制的实际情况及控制模型的整体设计,提出了适用的摩擦因数计算模型,进而简要介绍了摩擦因数模型关键参数的调试方式,并提出了一套间接评价模型精度的方法。通过现场测试和长期实际应用证明了模型的控制效果优异。     

近年来低合金高强度钢的进展

 从洁净钢生产、薄板坯连铸连轧无头轧制、薄带铸轧以及以快速冷却为核心的TMCP工艺等几个方面介绍了HSLA钢生产工艺技术的最新发展,并系统介绍了汽车用钢、船舶及海洋工程用钢、管线钢、建筑结构钢、核电用钢、压力容器用钢、工程机械用钢及集装箱用钢等行业所用的HSLA钢品种开发方面新进展。认为未来HSLA钢将向高强、高性能和低成本方向发展,对HSLA钢的发展有指导作用。     

洛阳栾川钼业公司制作大型纯钼坯的工艺及其性能

本文叙述了洛阳栾川钼业公司冶炼加工厂用粉末冶金方法生产大型纯钼板坯的工艺，并评价了板坯的性能，同时还简述了此板坯的开坯和轧制情况以及轧出的1．0mm厚的板材的室温和高温机械性能、塑－脆转变温度、再结晶温度及工艺性能。结果表明这种板坯基本符合轧制大规格板材的要求，轧制性能良好；用它轧出的板材的性能达到GB3876－83标准的要求。