共查询到18条相似文献,搜索用时 546 毫秒
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为保证连铸板坯动态轻压下技术的有效实施以减轻中心偏析和中心疏松,改善铸坯内部质量,针对实际生产时的非稳态浇注过程,根据铸坯表面温度的测量数据,修正了实时凝固传热模型,分析了拉速、过热度和二冷比水量等工艺参数的变化对不同钢种压下区间长度的影响规律。结果表明:拉速每增加0.1m/min,船板钢AH36和碳素结构钢Q235B的压下区间长度分别增加0.15m、0.21m;过热度每增加10℃,AH36和Q235B的压下区间长度分别增加0.01m、0.015m;二冷比水量每增加0.1L/kg,AH36和Q235B的压下区间长度分别减少0.04m、0.06m。将凝固传热模型应用于生产中,优化了动态轻压下模型,铸坯中心偏析减为1.0B~0.5C,中心疏松级别小于1.5级的铸坯比率由35.25%上升到85.16%,铸坯内部质量得到了明显改善。 相似文献
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从压下位置的影响和辊子变形的影响等方面,介绍了动态轻压下技术在连铸中的应用。该技术的应用改善了铸坯内部质量,减少了中心偏析和疏松,为实现高效连铸起到了重要作用。 相似文献
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】针对线材水平连铸生产中铸坯常出现拉断的现象,对铜模和铸坯之间的摩擦机理进行了研究。结果发现,由于铜模和铸坯之间长时间相互磨损,在铜模内表面生成一层从铸坯上刮下的铸坯材料膜,造成两者之间磨损加剧。由此采用和传统水平连铸完全相反的倒锥度铜结晶器,使铸坯被拉断的现象明显减少。 相似文献
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针对异型坯连铸二次冷却过程,基于凝固传热理论建立其二维凝固传热模型,采用非等间距网格离散空间区域,采用显式有限差分算法离散传热方程。以铸坯温度为控制目标建立了PID反馈控制模型。应用Visual Basic 6.0程序设计语言,开发了连铸二冷区离线动态配水控制软件,在铸坯拉速、浇铸温度和钢种发生变化后,该配水控制软件能够对进入二冷区的铸坯信息实行全程跟踪、记录、显示并动态地分配二冷各区的水量,保持铸坯温度分布的稳定。该软件界面友好、通用性强,运行结果证明其控制效果良好,从而为异型坯二冷水量实时动态控制系统的开发奠定了基础。 相似文献
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介绍电磁搅拌技术在连铸中的应用。该技术通过电磁力控制铸坯凝固过程中的钢水流动,改善铸坯的结构,提高铸坯质量与轧材性能。 相似文献
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针对传统连铸结晶器效率低、拉坯速度慢、铸坯表面及形状缺陷等问题,设计并加工了一种高效、高速、高质(Efficient,speedy and quality,ESQ)连铸结晶器内腔形线。基于矩形坯结晶器内传热和结晶收缩行为特性,推导并建立了结晶器铜管内腔形线几何模型,运算得到形线曲线表达式和锥度表达式。根据连铸坯热交换收缩组成模型,针对高碳钢材料大矩形坯规格修正原模型及表达式,将优化结果与钢厂传统形线对比分析。依托Matlab/GUI二次开发了结晶器形线尺寸输出系统,为现有钢厂设计并加工了230 mm×170 mm断面U71Mn钢种结晶器芯棒和铜管,保持其他连铸条件基本不变,使现有连铸机拉坯速度从1.1 m/min提高至1.6~1.7 m/min。结果表明,得到的连铸坯产品表面质量与原产品相近,且并无形状缺陷,验证了模型计算的合理性和正确性。相比于传统连铸结晶器内腔形线,新形线曲线提高了结晶器的换热效率,且保证了铸坯质量,这为增加连铸坯产量提供了基础。 相似文献
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K. H. Jung S. Lee Y. B. Kim B. Ahn E. Z. Kim G. A. Lee 《Journal of Mechanical Science and Technology》2013,27(10):3149-3153
The workability of ZK60A billets fabricated by semi-continuous casting, subsequent extrusion, and die casting were evaluated. To determine the deformation capability of the three different billets, upsetting tests were conducted at elevated temperatures and two different strain rates. The differences in critical height reduction depending on the casting methods were investigated based on inherent defects inside the billets, and variation in the mechanical property with the location within the semi-continuously casted billet was investigated by X-ray tomography and electron backscatter diffraction. Uniformity of density substantially affected the mechanical properties of the billet. The drastic decrease in the workability of the die-casted billet at temperatures higher than 320°C was also discussed. 相似文献
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为提高钢坯定重切割精度,分析了钢坯质量与钢坯平均拉速间的关联性。建立了钢坯拉速数据的模糊信息粒化模型,将每5根钢坯的平均拉速数据变换为一个三角型模糊粒,得到模糊粒子中的3个参数:钢坯平均拉速变化的最小值vLow、均值vmid和最大值vup,降低钢坯拉速数据的复杂度,得到含不同信息的拉速数据粒化子集。建立了基于信息粒化数据的支持向量机(SVM)回归模型,以模糊粒子参数为输入向量对钢坯平均拉速进行回归预测,得到下一根钢坯的平均拉速预测值。综合考虑钢坯截面积、钢坯平均拉速、定尺长度、下一根钢坯平均拉速预测值等影响因素,建立了极限学习机(ELM)神经网络预报模型,实现了钢坯定重预报。 相似文献
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《机械与工业》2000,1(6):639-649
Characterization of friction at the tool–billet interface in the cold forging of steel. A great number of steel billets used in the mechanical industry come from forging operations. That is to say that between the casting of the steel from the blast furnace to the ready to use billet, forging sequences such as drawing, backward and forward extrusions, stamping, etc., were involved, if necessary completed by cutting operations. The forging sequences, that can be carried out at or above room temperature, condition the integrity of the material. They are the source of residual stresses caused by plastic strains, that are usually needed to guarantee the good mechanical properties of the billets. On the other hand, they also imply severe conditions of contact which may lead to defects in the surface of the billets, such as scratches or cracks, or in core (tearing of sheets in stamping, etc.). The mastering of the conditions of contact is required in any optimization process of a fabrication line. 相似文献
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The modelling of metal forming processes in recent years has brought the development of different analytical and/or numerical techniques. The SERR technique is eminently suitable for analyzing drawing/extrusion of sections having re-entrant corners. However, in its present form, it cannot be used to analyse forming processes where the deformation zone has curved boundaries, since the elementary regions will no longer remain rigid. The present study is an endeavor to remodel this technique so that it can handle round billets. The circular cross section of the round billet is approximated by a regular polygon of equal area and the number of sides of the polygon is progressively increased until convergence of the drawing stress is achieved. As a test, the drawing of hexagon section bars from round billets through the straightly converging dies is analyzed 相似文献