环模制粒机粉体辊轧过程的有限元模拟

建立粉体辊轧过程的简化模型,采用Abaqus软件内置的Drucker-Prager Cap本构模型,通过有限元模拟技术分析粉体物料特性、摩擦系数、模辊间隙等对辊轧过程的影响。结果表明,随着粉体物料的不同,颗粒压制成型所需的挤压力差异较大;摩擦系数越大,模辊间隙越小,都将使粉体物料所受应力增大,使物料更易挤出模孔和提高挤压成型颗粒的质量。     

我国辊磨技术的引进、开发及应用

近几年来 ,我国在辊磨技术的引进、开发及应用有了迅速的发展 ,原因是辊式磨粉磨水泥生料时有其特点 :辊磨的粉磨机理是通过磨辊与磨盘的相对运动使物料得以粉磨 ,在粉磨过程中辊套与磨盘之间一般由物料层隔开 ,辊套与衬板之间的磨损很少 ;辊式生料磨集中碎、粉磨、烘干、选粉等工艺于一体 ,其流程简单 ;粉磨效率高 ;单位电耗低于钢球磨系统 ;尤其适于和预分解窑相匹配 ,可以利用出预热器的全部废气。综上所述 ,辊式生料磨是节能降耗比较理想的粉磨设备 ,辊式生料磨系统已成为当前生料粉磨系统的发展主导方向。在国外 ,为 2 0 0 0ｔ/ｄ水泥…     

环辊磨工作原理及加工细粉应注意的几个问题

环辊磨采用冲击、挤压、研磨的原理对物料进行粉碎，安装在磨环支架上的磨环与销轴之间有很大的活动间隙。当磨环支架随主轴公转时，磨环受离心力的作用甩向磨圈，并压紧磨圈内壁又围绕销轴自转，物料通过磨环与磨圈的间隙时，受到磨环的冲击、挤压、研磨而粉碎。粉碎后的物料在重力作用下，落到甩料盘而被甩至气流进入分级室进行分级，合格细粉通过分级轮进入后道收集系统收集，     

组合式冷轧支承辊热装等效应力研究

为准确计算辊套和辊芯热装等效应力,首次给出了考虑辊套和辊芯尺寸、材料物理性能参数及过盈量影响的辊套和辊芯热装径向应力计算公式,在此基础上得到了不同辊套厚度及过盈量条件下热装等效应力计算公式.为了验证该理论模型,用ANSYS软件对组合式支承辊热装过程进行了数值模拟,分析了不同辊套厚度、辊套和辊芯过盈量对结合面等效应力的影响.研究结果表明:相同过盈量及辊套厚度条件下,热装过程中周向应力约为径向应力的2倍;相同辊套厚度时,过盈量每增加0.1 mm,热装等效应力增大超过20 MPa;相同过盈量时,辊套厚度每增大100 mm,热装等效应力增大约20 MPa.     

斜辊矫直机中矫直辊辊形及其安装角的工程设计方法

本文通过对矫直辊与管材在理想接触条件下接触情况的分析，得出了工程计算矫直辊辊形的参数方程，为在数控机床上加工矫直辊辊形提供了方便，并根据接触理论给出了矫直不同直径管材时调整矫直辊安装角的工程方法。     

料层挤压粉碎理论与辊筒磨

简要地叙述了料层挤压粉碎理论（压碎学说），利用压碎学说探讨了辊简磨的粉碎机制，认为辊简磨的优越性在于它的4大特点，同时进行了辊筒磨粉碎产物的微观分析和粒度分析。     

斜辊矫旰机中矫直辊辊形及其安装角的工程设计方法

本文通过对矫直辊与管材在理想接触条件下接触情况的分析，得出了工程计算矫直辊辊形的参数方程。     

四辊平整机轧制过程多体接触耦合变形有限元模拟

为了提高四辊平整机的板型控制精度,采用非线性大变形弹塑性有限元法,考虑辊系弹性变形和轧件弹塑性变形的耦合关系,建立辊系与带钢多体接触的平整过程三维分析模型.利用该模型对不同轧制工艺条件进行的模拟计算,得到了平整小压下量时的接触压扁及应力状态分布规律和工艺参数对辊系弯曲变形及辊缝形状分布的影响规律.所建模型和分析结果可用于现场轧制过程离线分析和指导在线模型的设定.     

基于有限元法的磨粉机水冷式磨辊热应力分析

为了研究辊式磨粉机的磨辊温度效应产生的热应力及热膨胀,以水冷式磨辊为研究对象,建立辊体传热和热应力数值模型,利用有限元分析软件ANSYS对磨辊稳态温度场进行求解,完成热结构的耦合分析。结果表明:热应力导致磨辊轴颈处出现应力集中,最大应力值为201 MPa,温度效应引起辊体不同程度位移,位移量在0.054 5~0.163 0 mm之间,造成磨辊两头粗中间细的现象。     

瓦楞辊啮合机理及啮合方程的建立

首次对瓦楞辊在输入中间物-平板原纸成型瓦楞纸板的过程,着重进行了机理的研究。用微分几何及相对运动学原理建立齿廓函数及一对瓦楞辊的多点啮合方程。本结果是筛选U.V.UV型齿形,创造和尺度综合最佳楞型及其运动学和动力学分析、加工原理、误差计算和检测技术等的理论基础。     

Continuous generating grinding method for beveloid gears and analysis of grinding characteristics

Continuous generating grinding has become an important gear processing method owing to its high efficiency and precision. In this study, an adaptive design model is proposed for the continuous generation of beveloid gears in common gear grinding machines. Based on this model, a method for determining the installation position and grinding kinematics is developed alongside an analytical meshing model for grinding contact trace and derivation of key grinding parameters. By combining these aspects, a general mathematical model for the continuous generation of beveloid gears is presented, comprising the entire grinding process from worm wheel dressing to the evaluation of grinding deviation. The effects of the worm and dressing wheel parameters on the grinding deviation were analysed, facilitating the development of an approach to improve the grinding accuracy. The presented procedure represents a novel design method for the continuous generation of beveloid gears in common gear grinding machines, facilitating the appropriate selection of worm and dressing wheel parameters.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00388-z     

Effects of grinding aids on the grinding kinetics and surface morphological characterization of quartz

The kinetic parameters of a grinding process can be used to study the variations in particle size reductions and grinding efficiencies. Appropriate grinding aids usually change the surfaces of a material and the properties of the pulp, thus improving the grinding efficiency. In this paper, pure quartz samples with mixed particle sizes and single particle sizes were selected as the raw materials. The effects of different sodium tripolyphosphate (STPP) and citric acid (CA) dosages on the dynamic parameters k, selection function S₁ and breakage function B for quartz grinding were studied. The results showed that the STPP and CA enhanced the grinding process of the quartz. In other words, the parameter k, the selection function S₁ and the breakage function B were all increased to varying degrees. The results of SEM, BET and contact angle measurements showed that the surfaces of the quartz particles became rounder, the specific surface area and average pore size increased, and the surface hydrophilicity increased. As a result, the grindability of the quartz increased, and the grinding kinetic parameters changed. Finally, the results showed that the improvements in the quartz grindability were consistent with the influence of grinding aids on the kinetic parameter k, selection function S₁ and breakage function B_i,1.     

Impact of grinding aids on dry grinding performance,bulk properties and surface energy

In dry fine grinding processes the relevance of particle-particle interactions rises with increasing product fineness. These particle-particle interactions reduce the grinding efficiency and complicate the process control. The adsorption of grinding aid molecules on the product particle surface is a common measure to handle these effects. To ensure an efficient grinding aid application, the impacts of additives on particle and bulk properties, which influence the micro-processes inside the mill, need to be understood. Within this study the effects of several grinding aids on dry fine grinding of limestone in a laboratory vibration mill were investigated. Unlike in many other scientific works, the impacts of grinding aids were analyzed on different levels simultaneously: Grinding success and agglomerate size distributions were evaluated by wet and dry particle size measurements, respectively. Additionally, material coating on the grinding media, powder flowabilities and particle specific surface energies were measured. It was shown that all of the investigated grinding aids influence the grinding efficiency. However, the formation of agglomerates is not necessarily linked to the product fineness. Furthermore, a strong impact of certain grinding aids on the flowability of the product powder was determined. Thereby, the bulk flow behavior also determines the grinding result as it affects the stress mechanism inside the mill. Moreover, a direct relation between surface energy and powder flowability as well as agglomeration behavior could be demonstrated.     

SiC_p/Al超声振动辅助磨削砂轮选择方法研究

使用电镀金刚石砂轮、钎焊金刚石砂轮、陶瓷结合剂烧结金刚石砂轮和树脂结合剂烧结金刚石砂轮超声振动辅助磨削铝基碳化硅(SiC_p/Al),将砂轮磨损、材料去除、磨削表面形貌进行了对比分析,给出SiC_p/Al超声振动辅助磨削砂轮的选择方法。结果表明,陶瓷结合剂烧结金刚石砂轮在超声振动辅助磨削SiC_p/Al的过程中具有磨削过程平稳、材料去除均匀、工件表面质量好、砂轮磨损小的特点,是磨削SiC_p/Al的理想砂轮。本文的研究工作作为SiC_p/Al磨削工艺研究领域的一个方面,对SiC_p/Al磨削过程中砂轮的选择研究具有一定的指导意义。     

Experimental investigations into electric discharge grinding and ultrasonic vibration-assisted electric discharge grinding of Inconel 601

The paper presents experimental investigations into electric discharge grinding (EDG) and ultrasonic vibration-assisted electric discharge grinding (UVAEDG) of Inconel 601. The process parameters selected for both processes were duty cycle, discharge current, pulse on time, grinding wheel speed, work speed, and speed ratio to study their influence on responses like surface roughness (R_a) and material removal rate (MRR). It was found that duty cycle, wheel speed, work speed, discharge current, speed ratio, and pulse duration significantly influenced MRR and R_a. It was inferred that MRR increased with increase in duty cycle, wheel speed, current, work speed, and pulse duration in both EDG and UVAEDG processes. It was also inferred that R_a increased with rise in duty factor, pulse on time, and discharge current in EDG and UVAEDG processes.     

助磨剂对石煤提钒尾渣超细粉磨的影响

采用搅拌磨对钒尾渣进行超细粉磨,考察4种助磨剂的助磨效果,确定最合适的助磨剂为焦磷酸钠,对焦磷酸钠助磨产品的粒径分布、表面电位、表面吸附特性以及颗粒形貌等进行测定分析。结果表明,搅拌磨制备钒尾渣微粉的最佳参数为:添加焦磷酸钠质量分数为1.8%,矿浆质量浓度为1 g/mL,粉磨30 min,所得产品D_(50)=7.85μm、D_(90)=19.78μm,相比未添加焦磷酸钠的磨矿产品D_(50)、D_(90)分别减小了2.97、8.47μm,粉磨时间缩短至少10 min。焦磷酸钠通过在钒尾渣颗粒表面的吸附,增大颗粒的表面电位,减少微细颗粒在表面的粘附,降低矿浆黏度,从而提高钒尾渣的粉磨效率。     

Study into grinding force in back grinding of wafer with outer rim

Back grinding of wafer with outer rim (BGWOR) is a new method for carrier-less thinning of silicon wafers. At present, the effects of process parameters on the grinding force remain debatable. Therefore, a BGWOR normal grinding force model based on grain depth-of-cut was established, and the relationship between grinding parameters (wheel infeed rate, wheel rotational speed, and chuck rotational speed) and normal grinding force was discussed. Further, a series of experiments were performed to verify the BGWOR normal grinding force model. This study proves that the BGWOR normal grinding force is related to the rotational direction of the wheel and chuck, and the effect of grinding mark density on the BGWOR normal grinding force cannot be ignored. Moreover, this study provides methods for reducing the grinding force and optimizing the back thinning process of the silicon wafer.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-020-00316-z     

立式玻璃磨边机砂轮离心振动特性分析

针对立式玻璃磨边机砂轮架的结构特点,建立其动力学模型及系统运动微分方程,导出砂轮离心力作用下砂轮架与砂轮振动的稳态响应幅值及其动力放大因子β1、β2的理论计算公式,着重分析砂轮离心力激振下砂轮架及砂轮的振动特性及规律,结果表明：β1、β2的大小和砂轮与砂轮架的质量之比µ、固有频率之比α,砂轮角频率与固有频率之比λ,阻尼比ξ等因素有关;合理选择µ、α、ξ值,可使砂轮与砂轮架具有相同且较小的动力放大因子;避免砂轮工作在λ=0.9~1.1对应的转速范围内,可有效减轻砂轮架及砂轮的振动程度。研究结果突破了现有研究将砂轮轴刚性化处理、试验测试装备复杂等缺陷,具有物理概念清晰、计算简单等特点。     

Twyman effect mechanics in grinding and microgrinding

In the Twyman effect (1905), when one side of a thin plate with both sides polished is ground, the plate bends: The ground side becomes convex and is in a state of compressive residual stress, described in terms of force per unit length (Newtons per meter) induced by grinding, the stress (Newtons per square meter) induced by grinding, and the depth of the compressive layer (micrometers). We describe and correlate experiments on optical glasses from the literature in conditions of loose abrasive grinding (lapping at fixed nominal pressure, with abrasives 4-400 μm in size) and deterministic microgrinding experiments (at a fixed infeed rate) conducted at the Center for Optics Manufacturing with bound diamond abrasive tools (with a diamond size of 3-40 μm, embedded in metallic bond) and loose abrasive microgrinding (abrasives of less than 3 μm in size). In brittle grinding conditions, the grinding force and the depth of the compressive layer correlate well with glass mechanical properties describing the fracture process, such as indentation crack size. The maximum surface residual compressive stress decreases, and the depth of the compressive layer increases with increasing abrasive size. In lapping conditions the depth of the abrasive grain penetration into the glass surface scales with the surface roughness, and both are determined primarily by glass hardness and secondarily by Young's modulus for various abrasive sizes and coolants. In the limit of small abrasive size (ductile-mode grinding), the maximum surface compressive stress achieved is near the yield stress of the glass, in agreement with finite-element simulations of indentation in elastic-plastic solids.