热轧月牙肋钢筋横肋加工的设计及分析

本文分析了热轧月牙肋钢筋成品孔横肋槽的加工原理，介绍用普通铣床改造成铣月牙肋横肋槽专用机床，及如何加工轧辊横肋糟的设计方法，以保证轧辊孔型轧出符合国家标准GB1499－91《热轧混凝土用带肋钢筋》的月牙肋钢筋。     

螺纹钢成品轧槽横肋的铣切与控制

螺纹钢产品横肋末端间距是国标规定的一个外型尺寸质量检验项目。在实际生产过程中,辊缝设置、轧机弹跳、轧辊、轧槽加工质量是影响横肋末端间距的主要因素。本文对螺纹钢成品轧槽横肋的铣切工艺及加工过程进行分析,通过不断调整、优化、完善轧辊、轧槽加工工艺,确保横肋末端尽可能靠近槽口,消除加工质量对成品横肋末端间距产生的不良影响。     

热轧带肋钢筋横肋末端间隙超标原因分析及解决措施

2021年建筑材料产品质量国家监督抽查情况通报显示,热轧带肋钢筋抽查不合格率为8.6%,其中横肋末端间隙超标的就有11批次,占本年度不合格率的47.8%,是影响此次抽查不合格率上升的最主要原因。针对上述情况,结合昆玉钢铁的生产实践及工艺特点,分析了孔型设计、控轧温度、张力调整、钢坯外形尺寸和温度均匀性、横肋设计对横肋末端间隙影响,并提出了相应的解决措施,提高了横肋末端间隙的保障能力,有效提高了产品质量和生产稳定性。     

一种计算热轧钢筋成品辊轧制时前滑值的经验公式

通常热轧带肋钢筋轧制时,因成品需充填横肋和纵肋,使之金属流动过程复杂,造成影响前滑值因素增多,故计算其前滑值困难。充分利用钢筋成品轧制时,前滑值便于实测的有利条件,在对大量数据进行统计分析的基础上,归纳总结出一种经验公式,以便计算出棒材机组钢筋成品轧辊轧槽的横肋个数,从而准确确定出钢筋横肋间距,使得钢筋横断面金属量得到合理分配,促进了钢筋生产质量的稳定。     

切分轧制热轧带肋钢筋横肋顶端平面缺陷的控制实践

文章介绍了棒线材生产线采用切分轧制工艺,热轧带肋钢筋横肋顶端出现平面缺陷问题,该缺陷导致成品热轧带肋钢筋横肋高度不达国标.通过从切分轧制工艺孔型系统、轧制参数、工艺备件、调整方法等多方面入手,解决了切分轧制热轧带肋钢筋横肋顶端出现平面现象,从而提升了切分轧制热轧带肋钢筋成品质量,确保了热轧带肋钢筋产品符合国家标准.     

热轧带肋钢筋月牙型轧槽加工参数选择及计算方法

详细介绍了热轧带肋钢筋月牙型轧槽切削中 ,横肋斜角 ,铣刀回转半径 ,横肋槽数等参数的选择及计算方法。     

提高热轧带肋钢筋负差率的措施

本文介绍负公差轧制带肋钢筋时，采取控制加热温度，控制终轧温度，优化成品孔型设计等一系列措施，实现了负差率高、钢材外形尺寸和力学性能均符合GB1499-1998标准的要求。     

昆玉钢铁棒材生产线工艺技术改进

文章介绍了昆玉钢铁棒材生产线进行的工艺优化改进:针对生产工艺存在的横肋充不满,横肋高度低,钢材负差率低问题,优化了孔型设计;针对生产大规格钢材弯曲试验裂纹问题,改变横肋与钢筋轴线的夹角β,改变辊槽横肋根部加工方法,以及调整开轧温度、控轧控冷温度等措施,改善了钢材的冷弯性能;通过优化穿水管的内腔尺寸,增大水压,优化冷却工艺等措施,解决了多切分生产时钢材性能线差大、力学性能不稳定的问题。     

Φ12mm热轧带肋钢筋K1架次爆槽的原因

针对全水平机列四切分轧制工艺生产Φ12 mm热轧带肋钢筋时出现的K1架次成品孔型频繁爆槽的问题,对产生爆槽的原因进行了分析,对孔型冷却系统、孔型布置做了相应改进,严格控制了"黑头钢"和轧件头尾尺寸,最终解决了K1架次频繁爆槽的问题。     

热轧带肋钢筋负公差控制与成品孔槽设计的关系

利用3D软件,对热轧带肋钢筋底圆、横肋、纵肋进行了重量计算,各部分对负公差的影响大小依次为内径—横肋—纵肋,内径尺寸的设计是控制负公差的重点,对孔型设计、加工提出了原则性建议：设计较小的内径,适当加深横肋,减小螺旋角。     

横肋分布特征对带肋钢筋轴向变形分布的影响

实验研究了延伸变形在带肋钢筋中的分布.发现横肋对称的钢筋,延伸变形呈明显正弦规律分布;而横肋非对称的,变形相对均匀,无明显规律.随着变形量增加,变形分布的不均匀程度加重.分析表明:横肋对称的带肋钢筋,其不均匀程度较横肋非对称的严重,当钢筋整体变形达到2.8%时,前者为后者的2.5倍.从抗震的角度出发,建议提倡使用横肋非对称的带肋钢筋,且两侧横肋最好以肋间距的1/2交替分布.     

不锈钢/碳钢耐蚀海水带肋钢筋轧制复合工艺

摘要：海洋工程用带肋钢筋要求有耐氯离子腐蚀能力，但选用双相不锈钢生产成本过高，不锈钢 碳钢轧制复合钢筋则可兼顾耐蚀性和低成本。覆层采用2205不锈钢，基材为低合金钢20MnSi，用有限元方法模拟钢筋的热轧复合过程，分析轧制过程尤其是成品孔中轧件的变形规律。有限元仿真发现，矩形组合坯料无孔型轧制时，其角部复合困难，而成品孔轧制时，钢筋横肋根部的应变最大，覆层在此位置减薄显著，应选择合适的复合坯覆层厚度。在实验室采用焊接、真空处理和热轧方法制备了直径为16mm的复合钢筋，屈服强度为485MPa，抗拉强度为701MPa，断后伸长率约为37.1%，复合界面剪切强度为317.5MPa。复合钢筋呈良好的冶金结合，Fe和Cr的扩散层厚度约为40μm。该工艺生产的复合带肋钢筋成本较不锈钢降低50%以上。     

月牙肋钢筋相对投影肋面积的计算和保证

论述了钢筋肋面积的计算方法。结合月牙肋钢筋典型的成品辊加工曲线,提出了另一种新的肋面积计算方法。用新方法探讨了孔型设计、轧辊加工及工艺控制等关键环节对肋面积的影响。此外,对本计算方法与Ｓｉｍｐｓｏｎ方法的计算结果进行了比较。     

四切分轧制Ф12mm螺纹钢筋的线差分析及改进措施

分析了水钢三棒线四切分轧制Ф12 mm螺纹钢筋时成品出现四线差大的原因,其原因包括轧槽加工精度不高,孔型磨损不一致,轧机两侧辊缝不一致,第16架预切轧机(K4孔轧机)或第17架切分轧机(K3孔轧机)的进口未对正轧制线,K4预切分孔型和K3切分孔型设计不合理。通过提高K4和K3孔的加工精度,改进轧辊材质,将K4和K3道次导卫对正轧制中心线,将K4孔型连接带高度由原来的6.0 mm改为6.5 mm,缩小了四切分轧制Ф12 mm螺纹钢筋时的线差。     

Active wear and failure mechanisms of TiN-Coated high speed steel and tin-coated cemented carbide tools when machining powder metallurgically made stainless steels

In this study, active wear and failure mechanisms of both TiN-coated high speed steel and TiN-coated cemented carbide tools when machining stainless steels made by powder metallurgy in low and high cutting speed ranges, respectively, have been investigated. Abrasive wear mechanisms, fatigue-induced failure, and adhesive and diffusion wear mechanisms mainly affected the tool life of TiN-coated high speed steel tools at cutting speeds below 35 m/min, between 35 and 45 m/min, and over 45 m/min, respectively. Additionally, fatigue-induced failure was active at cutting speeds over 45 m/min in the low cutting speed range when machining powder metallurgically made duplex stainless steel 2205 and austenitic stainless steel 316L. In the high cutting speed range, from 100 to 250 m/min, fatigue-induced failure together with diffusion wear mechanism, affected the tool life of TiN-coated cemented carbide tools when machining both 316L and 2205 stainless steels. It was noticed that the tool life of TiN-coated high speed steel tools used in the low cutting speed range when machining 2205 steel was longer than that when machining 316L steel, whereas the tool life of TiN-coated cemented carbide tools used in the high cutting speed range when machining 316L steel was longer than that when machining 2205 steel. formerly with the Laboratory of Engineering Materials, Helsinki University of Technology     

The influence of austenite grain size and its distribution on chip deformation and tool life during machining of AISI 304L

In this article, the influence of austenite grain size and its distribution on chip deformation and tool life during machining of AISI 304L austenitic stainless steel bar is examined. Hot-forged bar and the quenched bars (at different quenching temperatures, 1050 °C, 1100 °C, 1150 °C, and 1200 °C) are machined at a high cutting speed. It was noted that the inhomogeneous distribution of grain size in the surface area, within a depth of 15 mm of the workpiece, resulted in tool edge breakage and lower tool life when machining the hot-forged bar compared with all of the quenched bars. In addition, a slight decrease in tool life was observed as the grain size increased in the quenched bars. The chip studies revealed that a higher segment height ratio of chip was gained when machining the hot-forged bar, compared to machining the quenched bars, due to the inhomogeneous distribution of grain size. Moreover, the thickness of the secondary shear zone was reduced as the grain size increased. Interestingly, it was noticed that the chip work hardened during the machining process due to strain-induced twinning and ɛ martensite transformation. The studies of tool wear and failure revealed that a crack was initiated on the flank face at the interface between the deposited workpiece and the tool substrate when machining the hot-forged bar. This crack was formed due to either the thermal and mechanical fatigue or plastic deformation of the tool substrate. The fatigue crack propagated into the tool substrate through the decohesion of interface between carbides. The criterion of tool life when machining all of the quenched bars was normal flank wear. Based on the studies of chip deformation and the mechanisms for tool wear and failure, the effects of austenite grain size and its distribution on tool life were explained.     

X63W铣床的改造

莱钢锻压力对Ｘ６３Ｗ铣床进行改造,重新设计齿轮箱,改造传动轴和承轴,用于加工螺纹钢成品辊横筋槽,满足了车间对螺纹成品辊的需求。     

Rare earth ceramic cutting tool and its cutting behavior when machining hardened steel and cast iron

The addition of rare earth element yttrium played an important role in the improvement of both mechanical properties and wear resistance of Al2O3/(W,Ti)C ceramic cutting tool material.Mechanical properties especially the fracture toughness and flexural strength were obviously increased when a suitable amount of the yttrium were added.Wear resistance of the developed rare earth ceramic cutting tool material was higher than that of the corresponding materials without rare earth in the machining of the hardened 45# carbon steel and cast iron HT20-40.Wear modes of the Al2O3/(W,Ti)C rare earth ceramic tool materials were mainly flank wear and crater wear accompanied with slight notch wear when machining the hardened carbon steel.Wear mechanisms were major abrasive wear at low cutting speed and adhesive wear at high cutting speed.Wear modes were nearly the same except that the adhesion phenomenon in the crater area was intensified when machining cast iron.The flank wear area was relatively smooth with no obvious plowing phenomenon which was possibly concerned with the workpiece of low hardness and the adhesion phenomenon at high cutting temperature.