布料溜槽结构对料流轨迹及高炉顺行影响研究

无料钟高炉炼铁矿料通过布料溜槽布于炉喉料面,此过程矿料的运动包括溜槽内运动及空区运动。准确描述矿料的运动过程,对实现高炉精准布料十分重要。布料溜槽过料面结构的稳定与否直接影响矿料运动轨迹,通过对矿料在溜槽内的受力分析,并结合工程验证,准确计算炉料矿料的落点,有利于高炉顺行。研究结果为高炉布料溜槽过料面结构设计及高炉布料操作提供了理论指导。     

胶带机漏斗的优化与改造

针对白马铁矿胶带运输系统中各矿石转载点的原漏斗结构不合理,漏斗磨损较快、漏斗磨穿撒料、预埋混凝土钢制漏斗钢板磨穿及漏斗堵料等情况,充分运用料打料的原理对各漏斗分别进行了优化和改造。在改造中,通过优化漏斗溜槽角度,采取安装挂式衬板、方钢衬板及形成料打料积料槽等方法,较好的解决了漏斗在使用中面临的上述问题。     

转载溜槽衬板磨损预测的DEM仿真方法

针对EDEM自动划分网格较稀疏问题,采用Hypermesh划分仿真模型网格,利用Herz-Mindlin接触理论的Archard磨损模型对转载溜槽磨损问题进行仿真,在网格单元上提取出漏斗和溜管衬板的接触能量和磨损量,分析了磨损量与接触能量的关系。假设转载溜槽衬板磨损深度为物料与溜槽衬板的使用时间为线性函数,根据现场衬板磨损量的测量值,将衬板的磨损系数关系的看作隐式的单变量方程,应用EDEM软件的仿真结果求解出磨损系数的标定值。分析了漏斗和溜管的磨损机理。该方法可用于转载溜槽的磨损预测。     

研磨铝矿球磨机衬板的失效分析

用扫描电镜等方法对研磨铝矿对球磨机衬板进行了失效分析。在热强碱腐蚀和冲击磨料磨损的综合作用下,高应力磨料磨损是衬板的主要失效机制,但未见应力腐蚀开裂现象。     

长寿命布料溜槽的研制

布料溜槽是无料钟式炉顶高炉中的一个重要部件。本文简要论述了各种布料溜槽在使用中的优、缺点,并着重介绍了套装型硬质合金耐磨衬板的结构形式、长寿原理及特点。     

煤矿刮板输送机溜槽失效分析及改进

阐述了刮板输送机溜槽的具体结构及运行原理,分析了溜槽故障原因,并针对磨料磨损、黏着磨损、腐蚀磨损、接触疲劳磨损等问题提出了相应的优化措施。对刮板运送机的溜槽失效问题进行改进,可延长输送机的使用寿命,增强运输能力,提高产能。     

第三次全国磨损失效分析及耐磨材料学术会议论文提要

本文对球磨机各种类型衬板,即ZGMn13衬板、ZGMn13Cr2衬板及ZG42CrMn2SiMo衬板的磨损表面形貌特征进行失效分析,并提出球磨机衬板选材方面的原则。实践表明,球磨机衬板在磨损过程中,一般是高应力碾磨损、凿削式破碎磨损及疲劳磨损的综合表现。由于衬板按装位置不同、磨料硬度,粒度不同以及衬板材质、形状结构等因素影响,衬板磨损的形貌也各不同。其失效方式主要是磨损,其次是断裂。在磨损过程中,磨料夹在衬板与磨球之间,经过磨球与磨料、磨球与衬板、磨球与磨球的撞击和接触,使磨粒受力而刺入衬板表面并产生相对滑移,使衬板表面产生犁皱。同时在压应力作用下,使衬板表面塑性组织产生变形、脆性组织     

立轴冲击式破碎机导料板的磨损分析与优化研究

针对立轴冲击式破碎机工作时转子导料板磨损严重的问题,提出采用工程离散元法建立导料板的磨损模型并结合正交试验、多元回归分析及多目标优化等方法对转子结构参数进行优化。首先,采用工程离散元法对导料板的磨损进行建模和仿真,分析了导料板磨损分布区域和累积接触能量对磨损的影响;其次,采用正交试验和极差分析法,揭示转子结构参数对导料板磨损的影响;再对正交试验数据进行多元回归分析,建立多目标优化的数学模型并进行优化。结果表明,当转子直径D=792 mm、导料板安装角α=35.3°及分料锥倾角β=24.5°时导料板磨损深度较小,且不会降低立轴冲击式破碎机的破碎性能,为改善转子磨损提供了一定的理论基础。     

基于近似模型和GMSCVE的溜槽结构设计优化

为减少焦炭长期冲击导致的物料输送溜槽磨损和破坏，提出了基于近似模型的溜槽结构设计优化方法。以溜槽冲击部位结构尺寸为设计变量，以焦炭运输速度为约束条件，构建了最小化冲击力的溜槽结构设计优化模型。为降低优化模型的计算复杂度，采用近似模型拟合冲击力、运输速度与溜槽结构设计变量间的隐式关系，并通过广义均方交叉验证误差准则筛选对隐式关系拟合精度最高的近似模型。通过EDEM仿真分析和实际运行，验证了该方法优化结果的可行性和近似模型的有效性。     

带式输送机转载溜槽导流板结构形状的分析

针对带式输送机转载溜槽设计问题,分别对普通冲击板、WEBA型冲击板、曲线型导流板、折线型导流板进行DEM仿真,对料流的速度矢量、冲击力和冲击系数进行了对比,根据仿真结果的观察和冲击力比较得出:WEBA型冲击板由于实现了料打料,降低了对冲击板的磨损,但导料效果不明显;曲线导料槽可以降低物料对衬板的冲击,并具有较好的导流效果;折线型导流板能够起到降低冲击和导流的作用,折线段越多降低冲击、导流效果越明显。研究结果为工程设计中冲击板或导流板结构形式的选择提供参考。     

Wear reducing effects and temperature dependence of tribolayer formation in harsh environment

Certain materials show a tribolayer formation especially at enhanced temperatures in abrasive environment, building a wear protection layer with the abrasive on the surface. Three materials with different microstructures were tested in three-body abrasive and impact/abrasive environments at temperatures up to 700 °C to investigate tribolayer formation. Optical and electron microscopical methods were used for wear qualification. Furthermore, hot hardness tests were performed up to 700 °C to investigate the influence of hardness drop on tribolayer formation.It was shown that no significant tribolayer formation occurs on grey cast iron, whereas other materials form tribolayers. Generally, tribolayer formation increases with increasing testing temperature, especially for austenitic and ferritic materials. This entails a self-protecting effect and thus superior wear resistance in abrasive environment.     

Quantification of the cold worked material inside the deep honing grooves on cylinder liner surfaces and its effect on wear

The increased presence of cold work material on cylinder liners due to the introduction of the diamond honing is undesirable as it seals the oil-bearing honing grooves. The most of it is a smeared metal inside the deep honing grooves (blechmantel) that may break and act as abrasive wear particles increasing the bore wear. An attempt has been made to estimate the extent of removal of blechmantel for different wear regimes present at the middle and top region (near the top dead centre) of the liner surface using the least worn bottom region as a reference for comparison. A number of truck grey iron cylinder liners were axially sectioned after varying periods of engine running under similar conditions of load, engine speed and lubrication. 3D surface measurements were taken at the three regions and a range of standard parameters was extracted. Combining the profile and image analysis, an algorithm was developed to identify and quantify the blechmantel. The algorithm has successfully identified/quantified the blechmantel and can be used for automatic surface quality and process control. It was found that the amount of the blechmantel in the middle section was approximately the same (though slightly lower) as that in the bottom section, while there was a considerable dislocation and removal of blechmantel in the top section and thereby it represents one of the possible causes for wear. Axial wear scratches of different size and distribution were observed not only through the whole stroke area, but also in the bottom region. All engines and liners performed well throughout the tests, and the observed quantities of blechmantel and axial scratches are acceptable for the time being.     

Abrasive wear behaviour of bamboo

Abrasive wear of bamboo (Phyllostachys pubescens) against a free abrasive consisting of quartz sand (96.5%-wt) and bentonite (3.5%-wt) was studied on a rotary-disk type abrasive wear tester (a free abrasive wear tester) and the micromorphology of the abraded surfaces were examined by scanning electron microscopy. It was observed that the bamboo fibre (vascular bundle) orientation with respect to the abrading surface had an important influence on the abrasive wear performance. The normally oriented specimens gave much higher abrasion resistance than the parallel-oriented ones, the surface layer than the inner layer, and the vascular bundle than the matrix tissue.     

基于退化过程的矿用自卸车货箱磨损预测分析

利用离散元法和有限元法的联合仿真,模拟矿用自卸车的卸货过程,求取了卸货过程中货箱底板各单元滑动磨损的时间历程。将磨损高度的变化设为连续随机动态过程,利用几何布朗运动建立了货箱磨损的退化模型。应用极大似然估计法和贝叶斯后验分布,计算底板各单元磨损高度变化的漂移率和波动率,实现对货箱底板磨损行为的预测。     

Al2O3-TiC陶瓷刀具切削铸铁缸套的磨损机理的研究

讨论了Al2O3-TiC复合陶瓷刀具切削HT200缸套的试验过程.缸套为离心铸件,切削性能较差;由扫描电镜对刀具的磨损形态进行观察,分析了刀具磨损特征及磨损机理.试验表明:刀具磨损机理主要为冲击磨损、磨粒磨损、扩散磨损等.     

The particle size effect on abrasive wear of high-chromium white cast iron mill balls

Granite grinding tests, under dry and wet conditions, were performed to assess the influence of abrasive particle size to the wear behavior of martensitic high-chromium white cast iron mill balls. The tests were performed, at first, using raw granite particle sizes between 0.074 and 19.1 mm, and then with coarse and fine granite fractions obtained after screening the raw granite in a 3.36 mm sieve. It is demonstrated that the relative particle/ball size relationship is the determining parameter to ball wear. The highest ball wear rates were observed for fine granite grinding under dry (120 mg/cycle) and wet (129 mg/cycle) conditions. The lowest wear rate (ca. 50 mg/cycle) was observed for coarse granite grinding (dry and wet). These different results were attributed to the different size relationships between grinding body diameter and granite particles size. For wet-grinding of raw granite, the mineral components may influence significantly the wear behavior. Feldspar can act as a bonding agent, gluing fine quartz particles to the coarse granite and to the balls surface and turning the dependence of the relationship between the relative sizes of ball and granite particle less important to the wear process. This explains why wet-grinding of raw granite results in a ball wear two times greater (106 mg/cycle) than dry-grinding (51 mg/cycle).     

Mechanical and tribological investigations of sol–gel derived SiO2 optical coatings

Sol–gel silica coatings were deposited on soda lime glass substrates by dip-coating. The silica films were amorphous, crack free, and smooth with an average roughness of less than 3 nm and thickness of 0.8–1.2 μm. Mechanical and tribological properties were investigated using nanoindentation, Taber abrasion and a polishing wear test. The hardness increased with increased thermal exposure from 2200 MPa for samples fired at 480 °C for 2 min to 3800 MPa for those fired at 560 °C for 14 min. In Taber abrasion, failure was due to penetration of the coatings by the abrasive particles of the Taber grinders, which caused scratches and subsequent delamination. For polishing wear experiments, hardness was inversely proportional to polishing wear rate. This suggests that hardness is a good indicator for the resistance of sol–gel silica coatings to polishing.     

Effect of surface nanocrystallization on abrasive wear properties in Hadfield steel

A nanocrystalline surface layer was synthesized on a Hadfield steel by shot peening treatment. The microstructure evolvement of the surface layer of the shot peening treated sample was characterized by optical microscopy, X-ray diffraction and high-resolution transmission electron microscopy. It has been shown that the grain sizes in surface layer were decreased to 11.1-17.4 nm after 60 min shot peening duration. Surface hardness was also increased greatly. Two- and three-body abrasive wear experiments were carried out for work hardening and original specimens, separately. The results showed that the wear resistance of the nanocrystallized Hadfield steel has distinctly been improved in case of soft particles used as two-body wear abrasives or light impact load applied for impact abrasive wear.     

Tribology of titanium boride-coated titanium balls against alumina ceramic: Wear, friction, and micromechanisms

The tribological performance of titanium alloy (Ti–6Al–4V) balls coated with a dual boride layer comprised of titanium diboride (TiB₂) and titanium boride (TiB) whiskers mated against alumina ceramic disks has been determined using lubricated ball-on-disk wear testing. Measurements of coefficient of friction values and volumetric wear were made and electron microscopic investigation of wear spots and tracks was performed. The wear rate of the boride-coated titanium alloy balls was 40 times less than that of 97% dense alumina balls. Measurements of wear track width and depth corroborated this result. The superior wear resistance is attributed to the hardness and the unique structure of the dual (TiB₂ + TiB) whisker layer and the consequent smoothness of the wear surface created during the wear process. The material removal mechanism is abrasive in nature in the boride-coated balls compared to grain fracture and pullout in alumina.     

Bore polishing — identification and simulation

Bore polishing resulting from the abrasive wear of the bore of diesel engines has become more evident with the introduction of turbo-charging and consequent high mileage. This paper identifies the principal characteristics of bore polish, suggests causes and records the examination of a particular used liner. A laboratory wear machine was then used to simulated bore polish conditions. The results are analysed and discussed.