Oxy-Gas burners for cold-metal open hearths

The installation and operation of oxy-gas burners in two tilting, acid open-hearth furnaces at Standard Steel Div. are described. The results of over 800 heats from two systems—in one furnace three burners are positioned over doors and in the other four burners are centered between doors—are given and compared. Firing rates and oxy-gas ratios for both installations are reported and evaluated. Increased production rates of 22–27%, decreased Btu input of 12%, and decreased costs of 13% are indicated.     

Permissible variations in the output of gas burners for heating and heat treatment furnaces

Conclusion The permissible variation of the heat output (or gas input) of gas burners can be taken as ±10% for heating furnaces and ±3% for heat treating furnaces.GIPRONIIGAZ. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 55–57, July, 1974.     

低压天然气烧嘴的研制与锻造加热炉改造

针对现有锻造加热炉中天然气烧嘴无法在2~8kPa低气压条件下实现正常点火或燃烧的现象,通过分析燃烧装置工作原理和气体燃料燃烧原理,以及加热炉火焰的流动方式、气流速度、燃气发热量及空耗系数等影响因素,对烧嘴和加热炉结构进行改进。通过增加烧嘴中央气流孔、加大中央孔直径、调整喷孔直径和数量等方法,设计了DTX3、DTX4和DTX5这3种结构的烧嘴,分别进行了点火及火焰试验,试验结果表明,DTX5烧嘴性能改善最显著。并采用DTX5新型烧嘴对加热炉进行风量计算、防爆筒结构及双层火焰设计改造与试验。试验结果表明,DTX5新型烧嘴适用于天然气压力2~8kPa、空气压力0.6~3kPa、调节比1∶8、火焰长度1~3m;改造后加热炉炉温均匀,炉温控制精度达±6℃,高出同类设备温控精度40%以上,生产率提高75%。     

异形截面环件虚拟轧制及其工艺优化

环件轧制是当前广泛应用于生产无缝环件的一种特殊塑性成形方法,然而轧制异形截面环件影响因素众多,控制环件成形具有高度的复杂性,采用传统的试凑法很难满足产品研发的需要。文章基于通用动力显式有限元软件ANSYS/LS-DYNA建立了RAW200/160-5型径轴向轧环机的三维仿真模型,并对斜L异形截面环件进行了虚拟轧制,实现了毛坯结构和轧制工艺的优化。结果表明,采用计算机模拟环件轧制生产过程,对于优化毛坯形状,制定或修改环件轧制工艺,缩减产品研发时间,降低生产成本,提高轧制效率具有重要意义。     

台阶锥形环件冷辗压中等效塑性应变规律研究

针对航空发动机中台阶锥形环件,以ABAQUS软件为平台,建立三维模型,研究了轧制过程中的等效塑性应变PEEQ变化情况,并根据台阶锥形环件截面特征,对关键点的等效塑性应变进行了分析,分析结果有助于研究该类零件轧制过程中金属流动规律.进一步研究发现,等效塑性应变平均值PEEQa随着芯辊进给速度的增加而减小,随着驱动辊转速的增加而增加.     

Researches on the ring stiffness condition in radial–axial ring rolling

The radial–axial ring rolling technology is used mainly to manufacture large rings in many industrial fields. During rolling process the ring may be collapsed or deformed unexpectedly under the pressure of guide roll, and in this case the ring is wasted. To prevent ring collapsing is necessary for smooth rolling. On the basis of rolling theory, the forces exerted to ring in radial–axial ring rolling process were analyzed, and the stiffness model of ring was proposed. The stiffness condition was derived and the influencing factors of ring stiffness condition were explained. The ring stiffness condition in radial–axial ring rolling is related to the factors of ring size, rolling ratio, position angel of guide roll, rolls sizes, position of cones, radial and axial feed speed and friction condition. The effect laws of some factors on ring stiffness condition were revealed by FEM simulation. The stiffness condition can be used as a rule of design and manufacturing for radial–axial ring rolling.     

An advanced manufacturing method for thick-wall and deep-groove ring—Combined ring rolling

Ring parts like duplicate gear, double-side flange and high pressure value body, are widely used in engineering machinery, which have the common geometrical characteristic of thick-wall, small-hole and deep-groove on the surface. The conventional manufacturing technology for this kind of ring is simple forging with cutting, which has the disadvantageous of high energy and material consumption, low material productivity and poor performance. In this paper, a new manufacturing method for this kind of ring named combined ring rolling (CRR) is firstly proposed based on the minimum resistance principle in metal plastic forming and its forming principle is introduced. Then, the reasonable ranges for key forming parameters of CRR are determined, the FE modeling and simulation analysis and experiment study for the CRR process with a double-side flange ring are performed. By this work, the CRR technique is testified feasible, and the basic thermo-mechanical deformation rules in CRR process are revealed based on simulation with the valid FE model proved by the experiment.     

沟球环件冷辗扩过程中截面变化规律

在沟球环件冷辗扩过程中,环件外径的增长预测和导向辊的位置确定是确保平稳辗扩的条件之一,而这两者的决定因素在于辗扩过程中截面形状变化。采用商业软件ABAQUS/Explicit对冷辗扩过程进行三维建模,预测沟球截面环件的直径增长和截面形状变化过程。在D56G90型冷辗环机上进行实验,测量了不同阶段的环件直径和沟球截面形状。将实验测量结果分别与解析计算结果和有限元计算结果进行比较,得出三者之间的差别,从而发现误差。利用解析结果和实验结果来修正三维有限元模型,以便更加精确地利用有限元模型来预测环件直径的增长规律和截面变化规律。模拟结果可以用于指导环件冷辗扩的工艺制定和生产,以期提高环件的质量。     

铸造GCr15轴承环径向热轧晶粒演变行为

径向热轧是应用广泛的轴承环先进塑性加工技术,铸造环坯径向热轧成形流程短、能耗低、材料利用率高,是一种低耗高效成形新工艺。与传统锻造环坯相比,铸造环坯初始晶粒粗大且不均匀,通过热轧实现晶粒细匀化是关键。文章基于铸态GCr15轴承钢材料本构模型,以SIMUFACT有限元软件为平台,建立铸造GCr15轴承环径向热轧仿真模型,通过热轧实验验证模型的可靠性。通过数值模拟,分析铸造GCr15轴承环径向热轧过程中晶粒演变规律,探究了轧制比、环坯晶粒尺寸、初始轧制温度对热轧过程晶粒演变的影响规律,为铸造GCr15轴承环径向热轧晶粒细匀化控制提供有效依据。     

辗扩成形系统的运动分析

研究辗扩成形系统的运动学规律, 导出了芯辊进给运动、环件辗扩成形运动 (包括环件直径扩大运动、环件转动和平动)、抱辊系统随动等的运动学方程, 确定了环件直径扩大运动速度和加速度、环件旋转角速度和角加速度的极限范围。为辗扩成形系统运动机构参数的设计和工艺设计提供了理论依据, 并为辗扩成形系统整体优化及过程控制、仿真奠定了基础。     

Upsetting of bi-metallic ring billets

This report examines the behaviour of bi-metallic components during the cold upsetting process. Each component consists of a solid inner cylinder around which is fitted a ring of a different material. In the first case experimental studies are conducted of a ring of mild steel C45E material surrounded by a softer C15E core. These tests are used to validate the finite-element models. The finite-element method is then used to extend the initial tests to a wider range of cylinder and ring geometries. It is also used to explore a second case where the materials are reversed to give a bi-metallic component with a stronger core. The principal objective is examine how contact between the inner cylinder and outer ring is maintained during the upsetting process. It is apparent that the geometries of the two component parts of the billet are the dominant factors affecting deformation, as the influence of changing the material has only a very small effect. With an initial height/outer diameter ratio of 1.5, contact at the cylinder/ring interface is maintained over the most of the initially contacting surfaces. A small cavity is formed when the inner/outer ring diameter reaches 0.6. Above this value the cavity will become larger, and at 0.8 the wall thickness is sufficiently thin to allow a double-barrel outer profile to develop with two cavities. With an initial height/outer diameter ratio of 1.0 or less, the formation of interfacial cavities is much less and demonstrates the viability of producing bi-metallic components in this way.     

错位环轧工艺

错位环轧工艺是在环件外周的适当位置安置两个辗压轮,同时在环件内孔的两辗压轮与环件接触处之间的近中部位置错位安置一个芯辊,外周的大辗压轮由电动机拖动旋转,它带动环件、芯辊和小辗压轮旋转,构成环轧,外周的两个辗压轮和内孔中的芯辊,在径向发生相向连续的进给运动的过程中,保持内外三个轧辊的错位状态,在此状态下,它们的径向压力难以穿透环件的壁厚,环件壁厚处于未锻透的状态,在轧制过程中,环件的断面面积变化不大,在咬入条件满足时,环件外周及内孔表面的局部连续受压,迫使环件外周表层金属发生轴向流动变形,去充填模具型腔,形成与模具型腔相对应的较复杂的断面形状。     

C型轮辋圈的轧制

根据环件轧制工艺及原理,介绍了一种C型断面轮辋圈的轧制工艺设计过程,包括其产品设计及模具设计.列举了各工序坯形控制的要点和主要参数,同时分析了轧制过程中的难点问题,并提出了有效的解决方法.该工艺的成功应用,使轮辋圈的材料利用率提高了28%,使生产效率提高了约一倍,具有一定的经济效益和社会效益;为今后生产此类复杂断面异形环件提供了新的思路和途径.     

盾构机滚刀刀圈体轧环工艺研究及模具设计

针对异形截面环件在实际轧制过程中影响因素较多、规律复杂、环件质量较难保证等问题,结合径向轧环轧制特点,提出径向封闭轧制成形工艺。以异形截面盾构机滚刀刀圈体为研究对象,借助立式轧环机、1000 t压机等设备,从工艺方案制定、轧制工艺参数选择、坯料形状设计、模具结构设计、轧制孔型安装调试等方面对轧环质量的影响进行了分析。结果表明：当轧制比为1.2～4.0、环件毛坯与锻件体积近似相等、环坯各截面圆滑渐变、毛坯内孔上下端面设置倒角,并且于轧制前将导向轮尽可能靠近环件、轧制后驱动辊多轧制几圈予以修型,可以消除环件的毛刺缺陷,提高了环件的综合力学性能、缩短生产周期、降低生产成本。     

42CrMo铸坯环件热辗扩有限元模拟与分析

基于ABAQUS软件平台,建立了42CrMo大型环形铸坯热辗扩三维热力耦合有限元模型,模拟了铸坯热辗扩过程中应变场和温度场,研究了初始辗扩温度对辗扩力的影响规律.模拟结果表明在环形铸坯热辗扩过程中：①铸坯等效应变呈阶梯状上升,内外表面应变大于中间层应变;在稳定成形阶段,沿环件径向方向,由于导向辊与芯辊直径差异,导致环件最大平均等效应变可能出现在环件内表面也可能出现在环件外表面;②初始阶段,变形区与成形辊接触处温度降低较快,非变形区温度变化不是很明显;随着辗扩的进行,芯部温度逐渐上升,边缘温度低,温度分布不均匀;③随着铸坯初始辗扩温度升高,平均辗扩力明显下降,但随时间变化趋势保持一致.     

铣齿加工大模数大型齿轮的方法

针对大模数大型齿轮加工存在的问题,提出采用粗加工→半精加工→精加工的加工工艺方案;并将车工序和铣齿工序、热处理与机加工穿插进行。设计了粗加工铣刀和精加工铣刀,按固定弦齿厚进行检测,保证了加工质量。     

GCr15铸环热辗扩孔洞形状演变预测模型研究

环件铸辗复合成形是利用铸造环坯热辗扩成形环件的一种短流程成形新工艺。然而铸造环坯中存在的夹杂、缩松、缩孔等孔洞类缺陷能影响到热辗扩成形环件的最终质量。基于ABAQUS平台建立了GCr15铸环孔洞热辗扩三维热力耦合模型,通过热轧实验验证了模型的可靠性,并研究了GCr15铸态环件不同径向位置孔洞缺陷在热辗过程中的演变规律,提出了一种铸环热辗过程中孔洞形状演变的预测模型。模拟结果表明,孔洞各向尺寸变化与孔洞位置密切相关,孔洞距离内径越近,其各向尺寸变化越大;根据初始铸坯的几何参数、相关热辗扩工艺参数和初始孔洞尺寸可以预测该孔洞在热辗扩过程中的形状演变情况。