钛合金棒材轧制的孔型设计与应用

设计了钛合金棒材轧制用椭圆-圆孔型,并在φ250横列式轧机进行了椭圆-圆孔型系统和椭圆-方孔型系统轧制钛合金棒材的对比试验.其结果表明,两种孔型系统轧制的棒材力学性能基本一致,组织均为两相区加工组织,无原始β晶界,但椭圆-圆孔型系统轧出的棒材晶粒较细小,等轴晶较多,外表面质量好,可提高钛合金棒材的成品率.轧后检查辊槽表面,发现椭圆-圆孔型系统的辊槽无明显变化,可减少换辊、修辊的次数,降低轧辊消耗.     

棒材轧制圆-椭圆-圆孔型中轧件面积计算模型

对GCr15轴承钢在圆-椭圆-圆孔型轧制后的横截面积进行了计算,并根据棒材生产线上的现场数据,考虑轧制速度对宽展的影响,通过使计算道次延伸率与实际值误差的标准差最小对现有模型中的宽展修正系数进行了优化,使轧后横截面积的计算值与实际值误差在±3%以内,说明模型具有较高的精度,可以为轧制GCr15轴承钢时的孔型设计和轧制工艺设定提供参考。     

20CrMnTi齿轮钢棒材热连轧有限元模拟

通过对棒材热连轧过程的分析,建立了20CrMnTi钢800~1150℃,变形量0~0.8,应变速率0~3 s^-1的Hensel-Spittel流变应力模型;利用LARSTRAN/SHAPE有限元软件模拟了20CrMnTi从200 mm×200 mm的方坯经8道次连轧为Φ90 mm圆棒的过程,分析了轧件在圆弧侧壁的圆孔型和直线侧壁的圆孔型下轧制过程中的应力场、应变场、温度场和轧制力及力矩的变化情况。模拟结果表明,轧件圆角部位等效应力、等效应变较大且温度较低,容易出现轧制质量缺陷;圆弧侧壁的圆孔型轧制圆钢时的精度略高于直线侧壁的圆孔型。     

轧制同轴复合棒材的芯材变形规律

棒材同轴复合时芯材与加工工具不接触，其横截面形状及尺寸精度控制难度大，采用方-椭圆孔型轧制时芯材圆度严重超公差。在建立覆材和芯材变形抗力模型的基础上，利用三维弹塑性热力耦合有限元方法对同轴复合棒材热轧变形过程进行数值模拟。分析了轧制孔型、覆材及芯材外形对轧制后芯材变形和形状的影响，用工业试验对模拟计算结果进行验证。结果表明：轧辊孔型设计对芯材不圆度的影响最明显，覆材及芯材外形是次要影响因素。这是因为方-椭圆孔型系统会导致最终轧件在横截面上的非对称等效累积应变分布，以及导致轧后芯材严重不圆。减少K4孔的轧件压下量，增加K3孔轧件压下量，可以改善方-椭圆孔型中轧件变形的对称性，减少芯材不圆度。     

斜轧孔型工艺H型钢初轧过程模拟仿真分析

为优化H型钢产品孔型工艺,提高孔型设计精度,利用有限元软件,对100mm×100 mm规格H型钢产品的初轧孔型进行轧制过程模拟计算,得到各道次轧件在变形过程中的孔型充满度、金属流动性以及应力应变的仿真结果.分析表明:在斜轧孔型初轧过程中,各孔型均未完全充满,K2、K3、K4孔型的闭口腿内侧金属与轧辊有脱离现象发生.K1...     

无孔型(平辊)轧制工艺——轧钢新技术讲座之二

无孔型轧制是指在无轧槽(孔型)的轧辊上轧制高宽比较大的轧件,即将常规有轧槽(孔型)的轧辊改为平辊,也称为平辊轧制。 在棒材和线材生产中,孔型轧制是最普遍采用的方法。其主要缺点是轧辊辊身长度的利用率低,在轧辊辊面上仅能加工成数量有限的孔型;其次,为了精确对正上下辊的槽孔,需要轴向调正轧辊;第三,孔型和导卫装置存在不均匀磨损,影响产品及中间半成品质量;第四,轧制不同规格产品要采用不同的孔型和导卫装置,频繁换孔     

三辊共轭孔型轧制圆形坯料的工艺设计与应用

为轧制料形尺寸准确的圆料、稳定生产，采用变通孔型设计方法对共轭孔型进行优化设计，通过对共轭孔型槽底、侧壁、压力差的变形设计，实现了共轭圆孔型在三辊粗轧机上的应用，轧槽咬钢顺利，成品圆料容易控制，完全满足后续工序的要求，同时减小了轧线的轧制事故，单套轧辊的轧制量可提高60％以上，取得了良好的经济效益。     

利用中间圆孔型轧制方坯工艺研究

主要研究圆孔型作为中间孔轧制方坯时的工艺变形特点,通过圆坯在菱形孔以及菱形轧件在后续方孔中变形规律的仿真分析,并对比方坯在菱形孔的变形特征,认为通过合适的轧制压下分配,利用圆孔作为中间孔轧制方坯在工艺上完全可行,完全可以轧制出满足尺寸要求的方坯成品。这种工艺配置不仅可以有效提高多坯型轧制时的孔型共用性,减少轧辊待机量,而且与常规菱方孔型轧制方坯的工艺相比,新工艺在改善成品角部质量,减少轧辊应力集中,减少轧件鱼尾变形量等方面具有明显的效果。     

无槽轧制技术在粗轧H-V机组上的开发应用

莱钢在棒材生产线粗轧H-V机组前5架轧机开发应用了无槽轧制技术。遵循轧辊最大利用率的原则设计轧辊的最大辊径与最小辊径,采用30%～40%的压下量,以Z.Wusatowskl宽展模型为依据,运用QBASIC编程软件设计了轧件宽展计算程序,确定各道次的压下量和宽展量,进口采用滑动导卫,通过单一改变辊缝即可调整轧件的断面尺寸,轧件变形更均匀。无槽轧制技术降低电耗1%,吨钢降低轧辊消耗费用5元。     

H型钢轧制技术的研究

本文比较全面地阐述了在350mm三机架可逆万能实验轧机上开展H型钢轧制技术研究的有关工艺技术问题,如万能粗轧机、轧边机、万能精轧机的轧辊孔型设计;按欧洲万能钢梁标准轧制H80×46mm型钢的轧制规程及轧制的H型钢样品尺寸精度;轧机调整;H形轧件在万能孔型中轧制时腿部宽展的变形研究,并给出了计算腿部宽展的公式;测定并分析了在万能孔型中轧制时的力能参数。     

自动轧管横向壁厚精度研究

摘要：针对自动轧管机轧制薄壁不锈钢管中出现的严重横向壁厚不均问题,借助于三维有限元分析软件Simufact,对X10CrNiTi18不锈钢管典型规格112mm×4.5mm自动轧管过程进行数值模拟。研究了不同轧辊孔型结构参数、芯棒润滑状态、轧辊孔型磨损及穿孔毛管偏心对自动轧管横向壁厚精度的影响。结果表明：随着芯棒摩擦因数的增大,所轧荒管横向壁厚精度明显恶化;偏心毛管轧制所轧荒管依旧偏心,延伸轧制对穿孔毛管偏心壁厚纠偏能力有限;磨损的孔型修模后,采用负芯补轧制较增大芯棒直径轧制所轧荒管横向壁厚不均度增大;采用三段式圆弧孔型,所轧荒管横向平均壁厚更接近目标壁厚,横向壁厚不均度由原孔型的13.55%下降到9.94%,横向壁厚精度明显改善。     

多道次立-平辊轧制立辊孔型对轧件头尾形状影响的有限元分析

 利用显式动力学有限元方法和几何模型更新方法模拟了不同立辊孔型下多道次立 平辊轧制过程,对轧后各道次的轧件头尾形状进行了分析。结果表明：采用平立辊轧制时,轧件影响深度比采用孔型立辊时小,且轧件尾部出现尖角,而采用孔型立辊时未出现;采用孔型辊时,孔型立辊底部导角大小对轧件头尾形状影响较小,且轧件伸长率比采用平立辊时大。同时,平立辊轧制过程头尾情况与用铅实验值吻合较好,说明了本次分析的正确性。     

Study on transverse wall thickness accuracy of tube rolled by automatic plug mill

In view of serious uneven transverse wall thickness of thin walled stainless steel tube rolled by automatic plug mill，the automatic tube rolling process of X10CrNiTi18 stainless steel tubes with typical specification of 112mm×4.5mm was numerically simulated by using 3D finite element analysis software Simufact. The influence of different roll pass structure parameters, different mandrel lubrication state, roll pass wear and eccentricity of pierced shell on transverse wall thickness accuracy of automatic rolling tube was analyzed. The results show that as the friction coefficient of the mandrel increases, the accuracy of transverse wall thickness of the rolled tube deteriorates obviously. The hollow tube rolled by eccentric pierced shell is still eccentric, and it shows that the elongation rolling has a limited ability to correct the eccentric wall thickness of the pierced shell. With repaired the worn pass, the unevenness of the transverse wall thickness of the rolled tube increases using the negative mandrel compensation rolling compared with the increase of mandrel diameter. The average transverse wall thickness of the rolled tube is closer to the target wall thickness by using three section arc groove, and the transverse wall thickness unevenness decreases from 13.55% of the original groove to 9.94%, and the transverse wall thickness accuracy is obviously improved.     

单机架轧机轧制Ф270mm～Ф300mm热轧圆钢的开发

介绍棒材厂在Ф750 mm单机架轧机上开发Ф270 mm～Ф300 mm热轧圆钢的工艺过程。通过选择设计适合初轧机轧制圆钢的孔型系统及工艺制度,包括孔型系统设计、轧辊孔型加工、加热制度、轧制制度、压下规程,使轧钢设备与工艺相匹配,开发出Ф270 mm～Ф300 mm圆钢,解决了生产过程中存在的难点问题。     

Surface Cracks in Wire Rod Rolling

Surface defects in wire rod and bar rolling are common and well‐known to mill people. Nowadays, surface defects are not accepted on high‐alloyed steel wire rods. The steel making, casting and rolling processes give rise to defects. Also, the final handling of the wire and bar can destroy the surface. In this work, artificial V‐shaped cracks in the longitudinal direction were investigated for different reduction series. The false round‐oval series are known as a series for high quality steels and are usually better than square–oval series. Experiments confirmed that in the false round‐oval sequences a surface crack in the groove bottom may open up during rolling at the same time as its depth is reduced, which is a beneficial situation. Surface cracks found at 45° to the rolling direction, at groove “corners” and on free surfaces will be closed or reduced in depth. The closing of cracks is detrimental since the cracks usually hide rolled‐in oxides beneath the bar surface. The experiments showed that for the subsequent oval–false round sequence the visible crack at the groove bottom will be closed and become shallower. The cracks at 45° and on the free sides will also be closed, but deeper causing a serious surface defect. An FE‐analysis was carried out, explaining the experimental results. Flat oval grooves are better than round ovals and false rounds are superior to square for opening and decreasing the depth of a longitudinal crack. It is difficult to eliminate a surface defect constituting a closed crack.     

轧制高强钢用新型冷轧工作辊的开发及其应用

针对高强钢、超高强钢的轧制生产需求,通过合金成分设计和制造工艺开发,研制出轧制高强钢用新型冷轧工作辊,工作层的耐磨性能以及辊体的强韧性得到显著改善。现场使用结果表明：单周期平均轧制吨位提高了约40%,单次下机磨削量降低了约7%,使用性能优于进口的同类型冷轧工作辊。新型冷轧工作辊适用于汽车用高强钢的轧制生产,硅钢、不锈钢及其他难轧板材等也有广泛的应用前景。     

高线粗中轧轧辊轧槽磨损规律浅析

轧辊槽面状况直接影响高速线材盘条表面质量,对粗中轧不同机架轧辊孔型磨损进行了大量测量,结果显示,无论是椭圆孔型还是圆孔型,孔型磨损都呈现极大不均匀性,槽底磨损量最大;沿轧制方向,磨损量逐渐增加,且椭圆孔型磨损量增加幅度高于圆孔型;单机架磨损量随吨位呈正相关关系。这些基本规律,有助于轧机操作人员适时地进行辊缝调整,更容易地控制料形。     

三辊粗轧机导卫系统优化设计与应用

三辊粗轧机因其往复多道次轧制的工艺特点,其导卫系统的稳定性极其重要,可操作性很强.莱钢小型合金钢棒材线三辊粗轧机导卫系统优化设计采用倒挂组合式导板梁、活动式进口装置、差异化翻钢板,能够很好地诱导轧件进入孔型,保证了料型尺寸精度和工艺的稳定顺行,事故率低,稳定可靠.     

New approach for prediction of roll force in rod rolling

Abstract

An approximate model is presented in which the equation for computing roll force in an oval-round (or round-oval) pass rolling sequence has been formulated with a new approach. The fundamental idea considered is to introduce the concept of a weak plane strain condition which gives a two-dimensional approximation of the three-dimensional deformation problem in rod or bar rolling. The generality and robustness of the model have been examined by conducting a two-pass low speed bar rolling experiment and a four-pass continuous high speed rod rolling test with various rolling temperatures, roll gaps (pass height), rolling speeds, and steel grades. The predicted roll forces were in good agreement with those experimentally measured, although the prediction was less good when the roll gap (pass height) varied. The proposed model was very fruitful in solving the three-dimensional deformation problem in rod or bar rolling.