基于试验设计方法的高颈法兰轧制工艺参数优化

建立了高颈法兰封闭轧制成形的有限元模型,基于DEFORM-3D有限元软件进行了高颈法兰封闭轧制过程模拟。应用试验设计方法研究了轧件初始温度、驱动辊转速、压实辊进给速度对成形质量的影响规律。通过正交试验设计和均匀试验设计方法对工艺参数进行了优化,得到了轧制工艺参数的最优组合。     

不同轧制条件下半固态变形的三维有限元分析

为了探索半固态钢铁材料流变轧制工艺,利用MARC有限元软件对弹簧钢60Si2Mn半固态轧制过程进行了三维有限元模拟,分析了在平辊和孔型轧制条件下的应力、应变场.结果显示,采用多孔材料的几何模型和刚-粘塑性有限元模型,能够正确描述半固态轧制的热-力耦合问题,反映了半固态金属具有低流变应力和良好流动性的特征.与平辊轧制相比,在孔型中轧制,轧件变形区横截面上应力、应变场分布更均匀.模拟结果与试验结果相吻合,说明半固态材料适合在孔型中轧制.     

SCR技术半固态制浆热流偶合场的三维有限元模拟

在ANSYS有限元软件求解平台上对SCR技术半固态制浆过程热流耦合场进行三维模拟,给出了不同工艺参数下的温度场和速度场的分布情况,并将模拟结果与实验结果进行比较.结果表明,在旋转工作辊拽动下,辊靴型腔内合金做层流运动,各流层的速度从工作辊表面到靴表面呈线性递减.合金温度从辊靴入口到出口逐渐下降,在速度场影响下,合金温度场等温线向工作辊面发生偏移,近工作辊面温度偏高.随着合金液浇注温度的升高、辊靴型腔高度的增加或者工作辊转速的提高,出口半固态浆料的温度升高,与实验结果一致.     

大型环件径轴向轧制成形仿真及试验研究

基于有限元分析软件Deform-3D建立了符合实际生产的316不锈钢环件热力耦合三维有限元模型.首先研究了径轴向环件轧制过程中的等效应变、温度场、轧制力能参数和金属流动速度场的变化规律;其次从环坯初始温度、驱动辊转速和芯辊进给速度三方面探讨了如何优选轧环机的问题;最后为验证本文模拟所得参数的可靠性进行了试验研究.将径轴...     

铝合金热轧开坯过程鳄鱼嘴现象数值模拟及成因分析

轧制温度、压下率、轧制速度以及辊径等变量是金属热轧开坯过程中控制鳄鱼嘴现象的重要工艺参数。借助Deform-3D模拟5052铝合金热轧开坯过程中的鳄鱼嘴现象,通过点追踪与正交试验相结合的方法得出影响鳄鱼嘴现象的首要因素。结果表明,在金属热轧开坯过程中影响鳄鱼嘴产生的首要因素为压下率,其次为轧辊直径和轧制温度,轧辊转速对鳄鱼嘴长度的影响最小。其次,在单道次轧制模拟过程中,当轧辊直径为450mm,压下率为20%,轧制温度为540℃,轧辊转速为5r/min时,产生的鳄鱼嘴长度最短。     

辊缝油膜承载力对冷轧机振动的影响

针对某冷轧厂在线轧制过程中轧机的振动问题,从辊缝油膜承载力的角度分析其对轧机振动的影响,得出轧制过程中辊缝间距的减小导致辊缝油膜需提供更大的承载力来维持轧机稳定。从乳化液浓度、轧辊转速、乳化液金属微粒含量方面探讨了增强辊缝油膜承载力的方法,得出乳化液浓度与轧辊转速在增强油膜承载力的同时减小了辊缝的摩擦系数,也易导致轧机振动。通过试验得出,调节乳化液金属微粒含量能够在原有摩擦系数的基础上增强辊缝油膜承载力,从而保证轧机的稳定运行。     

SCR工艺参数对A2017半固态合金组织的影响

采用自行设计的SCR实验机制备A2017半固态合金，研究了SCR工艺参数对A2017半固态合金组织的影响。实验结果表明，合金液浇注温度和轧辊冷却水流量共同影响辊靴间隙中半固态合金的固相率，降低浇注温度或者增大冷却水流量，辊靴间隙高固相率合金区间增长，晶粒尺寸变小；减小辊靴间隙或者提高轧辊转速提高合金层流剪切强度，利于枝晶破碎；增大出口半固态浆料冷却速率能有效抑制晶粒继续生长，保留其完整的非枝晶半固态组织。合金液浇注温度为760～780℃，辊靴间隙为4～6mm，轧辊冷却水流量200～300ml／s条件下，SCR技术可获得浆料状A2017半固态合金，凝固后坯料为均匀、细小的非枝晶等轴晶组织，晶粒大小在40～50μm之间，SCR技术是一种制备半固态加工坯料的理想方法。     

基于Fluent的铸轧因素对温度场影响的显著性分析

针对AZ31镁合金,建立了铸轧过程二维直角坐标系下的热平衡方程。对浇注温度、铸轧速度、水冷强度、轧辊辊缝、轧辊辊径等采用5因素4水平的正交试验法进行了数值分析。采用ANSYS下的Fluent进行了铸轧过程温度场的模拟,讨论了镁合金带材铸轧因素对温度场的影响大小。分析结果表明,轧辊辊缝是显著性影响因素,显著性置信度为95%,其次为铸轧速度、水冷强度、轧辊辊径。     

A356合金半固态充型过程的数值模拟

利用ANSYS有限元软件分别对A356合金轮毂压铸件在不同充型温度、压射速度条件下,半固态浆料的流动及其传热现象进行了耦合数值模拟。通过模拟结果的分析,考察了充型温度及压射速度对充型过程中半固态浆料流动及温度分布的影响,发现当充型温度为590℃、压射速度为5m/s时,半固态浆料充型效果最理想,有利于获得组织致密的成形件,为A356合金半固态压铸成形工艺的制定和优化提供了依据。通过试验,对数值模拟所获得的工艺参数进行了验证。     

硬质合金辊环在高线轧制过程中的热学行为模拟

本文研究了高线用硬质合金辊环在热轧过程中的不同轧制速度的热行为。以精轧机用粘结相含量为15wt%的硬质合金辊环为研究对象,采用有限元的方法,对轧制速度分别为40m/s、80m/s、160m/s进行轧制模拟。结果表明:随轧制速度的增加,辊环的温差变小,但产生高的温度变化速率和温度周期变化频率,正是高线精轧辊环表面由于热疲劳引起微裂纹的主要因素,影响辊环单槽轧制量和磨修量,缩短辊环寿命。     

AZ91D镁合金半固态铸轧工艺因素对组织的影响

在实验室半固态铸轧试验设备上进行了镁合金半固态铸轧试验,研究了AZ91D镁合金半固态铸轧组织的影响因素。结果表明,搅拌速度、铸轧温度对半固态镁合金组织有显著的影响。过快过慢的搅拌速度都不利于半固态组织的形成,试验表明搅拌速度300 r/min最佳;铸轧温度从高到低,固相率明显从小到大。     

Effect of roll gap adjustment on exit cross sectional shape in groove rolling—Experimental and FE analysis

We machined work roll with groove worn down as well as groove with no wear. We then performed a pilot hot rod rolling test at temperature of 1000 °C using plain carbon steel (0.1% C) as the roll gap decreases from reference roll gap (6.5 mm) to 3.5 mm. To understand better the effect of roll gap (i.e., section height) adjustment on the exit cross sectional area (ECSA) variation of workpiece in a two-stand groove rolling process with wear is considered, we carried out a series of three dimensional finite element analysis. Results reveal that variation of ECSA is almost linearly proportional to roll gap change while the roll gap decreases from reference roll gap (6.5 mm) to 3.5 mm. In oval groove rolling, the exit cross sectional shape and area predicted by FEA is in a good agreement with those measured. In round groove rolling, however, some deviations between FEA and experiment are observed because of roll groove geometry coupled with cross sectional shape of incoming workpiece. In the two-stand groove rolling, the effect of roll gap adjustment at each stand on the exit cross section of workpiece is somewhat different, in comparison with single-stand groove rolling. The roll gap adjustment at the previous stand has a more influence on the ECSA of workpiece than that of the next stand.     

Temperature field analysis and its application in hot continuous rolling of Inconel 718 superalloy

A coupled thermo-mechanical model containing metal flow and temperature field for calculating temperature variation has been developed on fourteen-pass hot continu-ous rolling of round rod for Inconel 718 alloy using 3D elastic-plastic finite element method(FEM).The temperature of characteristic analysis points in the intermedi-ate cross-section of the workpiece has been simulated at initial temperature ranging from 960 to 1000 °C and initial velocity in range of 0.15-0.55 m·s-1.Based on fi-nite element ana...     

MICROSTRUCTURE EVALUATION OF SEMI-SOLID STEELMATERIALS IN ROLLING PROCESS AND THERESULTING MECHANICAL PROPERTIES

1. IntroductionSemi-solid metal processing is a kind of near net-shape forming technology which hasbeen taken into account by the researchers all over the world. At present, six internationalconferences have been held. The semi-solid steel slurry direct rolling--rheorolling combinesthe fabrication of the semi-solid slurry with continuously rolling. This technology is differ-ent from the present rolling methods which are based on the dendritic .tructu.el1t2]. It is aneoteric rolling processing…     

Finite element analysis for the semi-solid state forming of aluminium alloy considering induction heating

The major objective of this study is to establish an analytical technique in order to investigate the behavior of semi-solid material considering induction heating of the workpiece. The induction heating process is analyzed using the commercial finite element software, . The finite element program, , for the simulation of deformation in the semi-solid state is developed in the present study. The behavior of semi-solid material is described by a viscoplastic model for the solid phase and by Darcy’s law for the liquid flow. Simple compression and closed-die compression processes considering induction heating are analyzed. To validate the effectiveness of the proposed analytical technique, the results of simulation are compared with those of experiment.     

The influence of some rolling parameters on the residual stresses after rolling

A 2D analysis of the deformation process in the rolling gap is presented. Flat strip rolling is considered for a low carbon steel at a temperature of 1000°C.

2D — Finite Element models with a rotating workroll have been installed using the Abaqus/Explicit-Code. The workroll is modelled as a rigid body. The main subject of the analysis is to show the influence of the phenomena taking place at the entrance to the rolling gap on the development of the stress and the strain fields in the rolled material. It can be shown that due to the shearing process the backward slip exists of the three zones A, B, C. The importance of these zones depends strongly on the shape coefficient Δ. The elastic — plastic modelling of the material behaviour allows the calculation of the residual stresses.     

工艺参数对楔横轧厚壁空心轴不圆度的影响

采用有限元软件DEFORM-3D对楔横轧厚壁空心轴进行热力耦合数值模拟,得到了工艺参数对楔横轧厚壁空心轴不圆度的影响规律。结果表明,在成形角35°～45°、展宽角4°～7°、断面收缩率35%～65%、轧制温度900℃～1100℃时,轧件不圆度与成形角及断面收缩率的变化成反比,与展宽角及轧制温度变化成正比。采用H630楔横轧机进行轧制实验验证了有限元模型的正确性。模拟与实验结果证明,轧件横截面失圆是楔横轧成形厚壁空心轴类件常见的质量问题;变形区金属沿轴向的流动受到未变形金属的阻碍,是造成不圆度在轧件的对称面上最大并沿轴向逐渐减小的原因。研究结果为确定楔横轧厚壁空心轴的工艺参数提供了理论依据。     

Prediction of effect of rolling speed on coefficient of friction in hot sheet rolling of steel using sliding rolling tribo-simulator

In order to reduce the rolling force and the roll wear, the lubricants have been used in hot rolling of steel. In order to evaluate the tribological behavior at the interface between roll and workpiece in hot steel rolling, it is important to measure the coefficient of friction and examine the effect of the tribological factors on the coefficient of friction. In this paper, the effect of the rolling speed on the coefficient of friction is investigated using the tribo-simulator testing machine for hot rolling developed by the authors. The workpiece used is SPHC. The roll material is SKD11 and the surface roughnesses are 0.05 μm, 0.2 μm and 0.8 μm. The rolling tests are carried out at a temperature of 800 °C during a rolling distance of 400 mm, changing the rolling speed from 15 to 70 m/min. The colza oil is used as a base oil and the emulsion concentrations are 0.1% and 3.0%. The coefficient of friction at an emulsion concentration of 3.0% is independent on the rolling speed. On the other hand, the coefficient of friction at an emulsion concentration of 0.1% decreases with increasing rolling speed in the lower range of rolling speed, but it increases in increasing rolling speed in the higher range of rolling speed.     

磁流变变间隙动压平坦化加工的工艺及机理

为提高光电晶片的磁流变抛光效率并实现其超光滑平坦化加工,提出其磁流变变间隙动压平坦化加工方法,研究不同变间隙条件下蓝宝石晶片的材料去除率和表面粗糙度随加工时间的变化,并分析磁流变变间隙动压平坦化加工机理。结果表明:通过蓝宝石晶片对磁流变抛光液施加轴向低频挤压振动,其抛光压力动态变化且磁流变液产生挤压强化效应,使抛光效率与抛光效果显著提升。在工件下压速度为1.0 mm/s,拉升速度为3.5 mm/s,挤压振动幅值为1 mm条件下磁流变变间隙动压平坦化抛光120 min后,蓝宝石晶片的表面粗糙度R_a由 6.22 nm下降为0.31 nm,材料去除率为5.52 nm/min,相较于恒定间隙磁流变抛光,其表面粗糙度降低66%,材料去除率提高55%。改变变间隙运动速度可以调控磁流变液的流场特性,且合适的工件下压速度和工件拉升速度有利于提高工件的抛光效率和表面质量。