影响20Kg铝锭铸造机组脱模的因素及改进措施

本文针对20Kg铝键铸造机组生产中存在的脱模率低的问题，对影响脱模的因素进行了较全面的分析，提出了多项改进措施并付诸于实战，使20Kg铝键铸造机组脱模率达到了95％以上。     

铁合金连铸粒化智能加工装包系统的设计开发及应用

为解决铁合金生产过程中精整加工环节存在的劳动生产率低、成本高、粉化损耗严重等问题,针对目前铁合金连铸机普遍存在模具损耗严重、难脱模、产品污染严重的问题进行深入的研究,设计开发了一种可使铁合金从液态至装包过程全自动智能化、脱模率高、粉化率低的铁合金连铸粒化智能加工装包系统,并且在加工过程中可使合金中的有害成分C、P、S得到了有效的控制。     

粉末微注射成形脱模过程的有限元模拟

本文选取圆柱状微结构的截面作为研究对象,分析了粉末微注射成形脱模过程中脱模阻力的构成。在保压压力为10 MPa,脱模温度分别为60℃、80℃、100℃和140℃条件下,利用有限元方法模拟了微结构在脱模过程中处于不同位置时的应力分布状态及变化趋势。结果表明:在脱模刚开始时,微结构受到的应力最大,最容易造成微结构破坏。在脱模温度低于临界平衡温度(T_(cr))时,脱模温度越低,微结构受到的应力越大,微结构距离生坯几何中心越远,其承受的应力越大,越容易造成微结构的破坏;在脱模温度高于T_(cr)时,在整个脱模过程中,生坯中的各个微结构处于相同的应力状态。     

一种简单的钢锭强制脱模吊具的应用

钢锭的脱模方式有自重脱模和强制脱模两种。在一般情况下,约有90％的钢锭靠自重就可以脱模,需要强制脱模的钢锭约占10％。我公司炼钢厂由于没有强制脱模设备,自投产以来需强制脱模的钢锭无法脱模,造成大量钢锭模不能重复使用,钢锭无法交付生产,给生产带来很多不便。 为了解决这一问题,我们参考专用脱锭     

一种多平行小孔件的成形模具设计

多平行小孔粉末冶金零件不仅成形困难,而且脱模也困难。本文介绍的成形模具,通过对压制芯杆及脱模筒等模具零件的特殊设计,不仅可以直接成形多平行小孔零件,而且可以交两次脱模为一次脱模,从而大大提高了生产效率。     

海绵钛电极块压制模具的结构优化

针对80 MN海绵钛压机所压制的电极块从凸模中脱模困难及电极块密度分布不均的问题,通过有限元软件模拟分析了电极块在脱模过程中,凸模和电极块的应力场、主应力、速度场分布情况,定量分析了电极块所受的摩擦力,找出了脱模困难的原因。在此基础上,优化了凸模成型面形状,模拟分析了优化后凸模尖角处的强度、脱模过程及电极块的密度分布情况。优化后的凸模不仅彻底解决了电极块脱模困难的问题,而且电极块密度不均匀的情况得到了改善。     

锌锭脚锭生产试验

文章阐述了锌锭配脚锭的必要性，设计了不同规模的脚锭进行了脱模试验，认为锭模内腔光洁度是影响脚锭顺利脱模的重要因素，而锭脚的高低及相应的斜度不是决定能否脱模的主要因素。     

粉末微注射成形模具技术研究进展

粉末微注射成形技术是一门新型粉末冶金近净成形技术,由于具有显著的优势和广阔的市场前景而成为当今世界最热门的零部件成形技术。受多因素的影响,注射成形及脱模过程中的摩擦行为将影响模具的使用寿命及可靠性。本文阐述了粉末微注射成形过程中模具磨损研究状况,重点介绍了微型模具加工技术及脱模过程中脱模力计算、数值模拟、粘附现象以及模具表面改性和脱模剂使用对脱模性能的影响,并对未来的研究方向进行了展望。     

20kg铝锭连续铸造机不脱模检测报警及二次打击系统设计安装

分析了20 kg铝锭连续铸造机存在的问题,设计安装了不脱模检测报警及二次打击系统。该系统能对铝锭出现未脱模时及时报警,并对不脱模铝锭进行精确打击。本系统可安装在铸造机的有限空间内,具有结构紧凑、设计精巧和自动化程度、运行的可靠性、安全性高的特点。     

湘钢提高钢锭成坯率因素浅论

钢锭的表面质量、头尾质量及形状,脱模废以及轧制工艺等,与钢锭的成坯率有着密切的关系。近年湘钢在提高钢锭成坯率方面作了一些工作,现简介如下。 1 生产情况分析湘钢于1992年1～3月对现行工艺生产中出现的废品进行了分类统计。 1.1不同钢种脱摸废和轧后废     

200kA铸造冷却水设备改造的经济分析

铝锭铸造机组是铝冶炼企业形成最终产品的重要工艺设备,设备的平稳运行和充分发挥机械效率,是保障日常生产需求与最终产品外观质量的基本条件。本文针对连城分公司200 kA铸造车间20 kg铝锭连续铸造机组循环水设施和铝锭连续铸造机组主体部分存在的问题和局部设计改造进行了论述与经济分析。通过对ATZJ2-20/16-Ⅱ.20 kg铝锭铸造机组的进一步优化改进,使日常生产中铝锭脱模率由设备改造前的20%左右,提升到了设备改造后的98%以上,生产过程中铝锭脱模率低、产品外观质量有缺陷的"瓶颈"问题得到了解决,在人力、财力、物力、电力方面节省了开支,同时企业经过工艺设备的优化改进,提高了水资源的再循环利用,进一步完善了企业节能减排工作目标,降低了铝锭的生产成本。     

锻轧复合用途5.5-7 t钢锭模的研制

锻轧复合用钢锭模是一种高效率、低成本、用途广的钢锭模,基于钢厂大量方锭生产经验并依据钢锭模设计原理对钢锭锥度、高宽比、帽容比、锭模厚度等参数进行设计,开发了锻轧复合用5.5～7 t方锭钢锭模。生产实践表明,采用设计参数为3.8%锥度、2.0～2.5高宽比(可调节式帽口)、12.5%帽容比、上薄下厚式壁厚(上部150mm,下部175mm)的钢锭模,钢锭质量提升效果明显,锻造成材率由原83.0%提高到85.0%。     

SCM822H钢3t铸锭缩孔缺陷优化的数值模拟

在现场脱锭时铸锭表面温度测定值的基础上,利用ProCAST软件建立了SCM822H钢(/%:0.20C、0.80Mn、O.25Si、0.013P、0.006S、1.14Cr、0.39Mo、0.01V、0.036A1、0.000 2B)3 t铸锭(锭身高1 675 mm,冒口倾角65.3°,冒口内液面高290 mm)充型和凝固过程的计算模型。通过该模型计算得出冒口倾角、锭身高宽比与缩孔引起的锭身切除体积比的关系,优化了锭型参数一锭身高宽比为1 864/530,冒口倾角90°。按照优化锭型参数的模拟结果表明,采用新锭型可使锭身切除体积由原先的13.5%降至0,可保证将缩孔缺陷完全控制在冒口内。     

Investigation of panel crack formation in steel ingots: Part I. Mathematical analysis and mid face panel cracks

An investigation of panel crack formation in steel ingots has been undertaken to improve understanding of the mechanisms by which the cracks develop and to evaluate possible solutions to this problem that has plagued the steel industry intermittently for decades. The investigation features the application of two-dimensional, finite-element, heat-flow, and stress models, which have been described in earlier publications^1,2 for steel ingot processing. The model predictions have clarified the role of stress generation in panel crack formation and demonstrate the importance of the γ→ α phase transformation. It has been revealed that two distinct types of panel cracks, both of which are partly caused by intermediate-temperature embrittlement of steel involving aluminum nitride precipitation, operate under different mechanisms. Mid-face panel cracks, which are analyzed in Part I of this paper, apparently form during air cooling when the mid-face surface is between the Ar₁ and 500 °C. The cracks can be prevented by ensuring the ingot surface does not cool below the Ar₁, and preferably the Ar₃ temperature. In case of a 335 mm square ingot, this would require reheating and rolling within the first hour after being stripped from the mold. Alternatively charging the ingots to a holding furnace to slow the surface cooling rate through the critical Ar₁ – 500 °C temperature zone should be beneficial. Off-corner panel cracks are discussed in Part II.     

Investigation of panel crack formation in steel ingots: Part I. Mathematical analysis and mid face panel cracks

An investigation of panel crack formation in steel ingots has been undertaken to improve understanding of the mechanisms by which the cracks develop and to evaluate possible solutions to this problem that has plagued the steel industry intermittently for decades. The investigation features the application of two-dimensional, finite-element, heat-flow, and stress models, which have been described in earlier publications^1,2 for steel ingot processing. The model predictions have clarified the role of stress generation in panel crack formation and demonstrate the importance of the γ→ α phase transformation. It has been revealed that two distinct types of panel cracks, both of which are partly caused by intermediate-temperature embrittlement of steel involving aluminum nitride precipitation, operate under different mechanisms. Mid-face panel cracks, which are analyzed in Part I of this paper, apparently form during air cooling when the mid-face surface is between the Ar₁ and 500 °C. The cracks can be prevented by ensuring the ingot surface does not cool below the Ar₁, and preferably the Ar₃ temperature. In case of a 335 mm square ingot, this would require reheating and rolling within the first hour after being stripped from the mold. Alternatively charging the ingots to a holding furnace to slow the surface cooling rate through the critical Ar₁ – 500 °C temperature zone should be beneficial. Off-corner panel cracks are discussed in Part II.     

基于钢锭氧化的空燃比调节技术研究

通过对钢锭加热生成的氧化铁皮的结构和成分的分析,找出钢锭氧化对空燃比的影响,并推导计算出空燃比的修正系数,对提高燃烧控制的水平具有重要意义。     

Influence of Mould and Insulation Design on Soundness of Tool Steel Ingot by Numerical Simulation

 The solidification of 4. 4 t cold work tool steel ingot type X210Cr12 was simulated by Magma software. By the reduction of ingot height, solidification modeling and pouring of a new 3 t ingot were performed and decreasing the porosity formation potential in 3 t ingot in comparison with 4. 4 t ingot on the basis of Niyama criterion was observed which was in good accordance with experimental data. In order to produce sound ingot, a new 2. 8 t ingot mould was designed which includes some parameteric changes in mould such as mould slope, slenderness ratio, mould concavity radius, fillet radius of mould internal corners and feeding diameter to ingot upper diameter ratio. Furthermore, the effects of insulating between kokil and feeding ring and also insulating the outer surface of feeding ring as well as insulating the outer surface of one third of kokil upper part on centerline porosity formation were investigated in both 2. 8 and 4. 4 t ingots. The results show that the ingot which was produced in new designed 2. 8 t mould has a better Niyama pattern and the centerline porosities were eliminated.     

基于凝固数值模拟的13t扁锭结构设计与优化

在同时考虑热量、动量和质量传输的基础上建立了三维凝固有限元模型,其模拟结果如凝固进程、缩管及偏析等已得到以往试验和数值研究的验证。基于该模型,预测了某厂13.1t扁锭凝固缩松和偏析等缺陷的分布特征,并根据铸锭致密度和均质性分析结果对宽厚比和高径比进行了优化设计。结果表明,宽厚比和高径比均对扁锭凝固内部质量具有重要影响,且两者优化后对Q235中心疏松和偏析的改善程度比70CrMn显著。对于“一型多用”的钢锭模来说,应按照高合金钢种凝固质量控制进行结构设计。钢锭凝固过程中缩松与偏析相伴而生,这在数值模型中应该同时考虑。     

Mechanism and kinetics of bubble formation in doped tungsten

The mechanisms and kinetics of bubble formation that occur during annealing of tungsten doped with small amounts of K, Al, and Si compounds has been investigated by electron microscopy. Bubbles are present in the sintered ingot due to volatilization of the dope during the sintering treatment. As the ingot is worked down into wire, the bubbles present in the ingot become elongated. On annealing these elongated bubbles undergo shape changes which depend on the amount of working. Elongated bubbles with a length-to-width ratio of less than ten spheroidized while those with a length-to-width ratio greater than twenty are unstable and break up into a row of bubbles. If working has been sufficient to close up the elongated bubbles,e.g., in ribbon, 0.125 mm thick rolled from 0.9 mm diam wire, bubble formation results from the diffusion of vacancies to the volatile dopant particles.     

Improvement in Quality and Yield of the Low Alloy Steel Ingot Casting Through Modified Mould Design

The internal quality and yield in 4 ton steel ingot of 40cmd8 grade was studied by comparing its solidification in a square cross-section mould with a slender rectangular cross-section mould, using FEM simulation. The model predicted various solidification aspects like fluid flow, thermal and solidification profiles, mushy zone, local solidification time, porosity and piping for both the molds. The convective flow of the molten metal during solidification showed higher velocity in square ingot than rectangular ingot under similar conditions due to lower surface area to volume ratio that affected the heat transfer in the rectangular ingot. Higher amount of air gap between the ingot and the mould was formed in rectangular ingots. Lower microsegregation as measured in terms of local solidification time was observed in rectangular ingot. Based on microstructure parameters such as thermal gradient and rate of solidification, it was found that the square ingot had more equiaxed zone than rectangular ingot. The rectangular ingot solidified at a faster rate and showed more propensity for core porosity than the square ingot. The ingot yield was improved by 3.6% through mould shape modification from square to rectangular. Model was validated to limited extent by carrying out a typical experiment with square mould.