刍议辊式立磨系统技术改造

辊式立磨系统技术是粉体加工行业的核心技术,这种技术是与传统管磨机相区别的。随着生产技术的发展,辊式立磨系统本身也获得了深入发展。在粉体用量越来越多的背景下,原先的管磨机系统技术已经不能适应时代发展的要求。在当前人们对粉体加工行业的要求越来越高的背景下,加强辊式立磨系统技术的研究有着重要意义。本文将重点探讨辊式立磨系统技术。     

MLS4500单辊加载立磨在水泥生料粉磨中的应用

立式辊磨机技术日益完备,立磨已经成功应用于生料制备、粉磨矿渣、脱硫制粉等领域。北方重工集团有限公司基于成功开发的单辊加载矿渣立磨基础上,在不改变原有磨型前提下,开发出的单辊加载水泥生料立磨使得磨机产量得到大幅提高,设备在节能减排方面优势显著。     

大型单辊加载脱硫立磨的设计与应用

立磨在制备脱硫用石灰石粉的过程中被广泛使用,具有粉磨效率高、运行平稳、能耗低、清洁生产等优点。本文主要阐述了立磨的工作原理和工艺系统,并通过与集中加载立磨的对比,分析了单独加载脱硫立磨的技术优势,指出了大型单辊加载立磨能够取代现有小型立磨成为脱硫工艺的主机设备。     

中卸式柱磨机与辊压机、立磨、卧辊磨的工作原理及特点相比较

众所周知，磨矿碎矿工艺中电耗占整个生产综合电耗的70％左右，为了寻求粉碎工业领域的增产节能途径，多年来实验研究的重点一直集中在粉磨工艺及设备的节能上。     

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。     

磨辊开裂原因分析

磨辊在热处理之后发生开裂，裂纹宏观形貌平直。为寻找开裂原因，对开裂磨辊进行了化学成分和高、低倍组织及断口的宏、微观分析。检验结果，宏观断口上有较多白亮斑，低倍试样上分布大量锯齿状白点裂纹；用SEM观察断口的白亮斑区有不连续二次裂纹，二次裂纹边缘分布多个穿晶准解理平台，平台微观形貌与白点的微观形貌特征相符；金相组织是由粗大马氏体、贝氏体和珠光体与铁素体组成的混合组织，且有不连续分布的穿晶锯齿状裂纹，裂纹周围未脱碳。结果表明，磨辊开裂是由白点引起的，而白点裂纹的形成与磨辊材料的氢含量和热处理组织缺陷等因素有关。     

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）利用压碎学探讨了辊筒磨的粉碎机制，认为辊筒磨的优越性有它的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。     

水泥厂原料立磨的使用问题分析

水泥厂为我国的经济的发展提供了原材料，在工厂存在众多的设备和系统，其中设备的正常运转是整个水泥厂正常运转的前提。本文将对立磨系统进行分析，探析立磨系统的操作技术，并针对系统中出现的问题进行针对性的提出措施。     

立辊轧机的结构与装配要点分析

随着我国经济的快速发展,对于钢材这一工业的基石需求量大增,在钢材生产的过程中,立辊轧机不但起到了疏松板坯表面的氧化铁皮用以除磷的作用,在轧制薄板带钢的生产过程中所起的作用也越来越重要。本文将对立辊轧机在装配过程中需要注意的问题进行介绍。     

卧式行星磨粉磨过程的无因次量及数学模型分析

以卧式行星磨为研究对象,从选出的9个参变量中利用量纲分析法导出6个表征粉磨过程的无因次准数,利用决定性、非决定性无因次准数之间的关系,建立粉磨产量、粉磨能耗2个数学模型,并利用多重线性回归分析正交试验结果得到数学模型。结果表明,模型的相关系数大于0.8,且实测值与模型理论预测值的相对误差约为15%,证明了数学模型的正确性。     

聚能锥角对线性聚能爆破致裂岩体效果的影响

为研究不同聚能锥角下线性聚能爆破致裂岩体效果,在巷道岩壁开展了5种聚能锥角(40°、50°、60°、70°、80°)下的聚能爆破和岩体损伤测试试验,数值模拟了不同聚能锥角形成的聚能射流。结果表明:线性聚能爆破定向致裂岩体效果显著,聚能方向损伤增量显著大于非聚能方向;聚能锥角为40°时致裂岩体效果最好,最大损伤增量达0.93,裂纹扩展深度和长度较大,50°、60°、70°和80°聚能锥角时,最大损伤增量、射流压力、射流长度、射流头部速度、射流尾部速度等均随聚能锥角的增大而减小,致裂岩体效果逐渐减弱。     

双锥药型罩结构参数对聚能射流的影响

为探究双锥药型罩结构参数对聚能射流速度的影响,采用数值仿真模拟双锥型药型罩形成射流的过程。结果表明:双锥药型罩较单锥结构形成的有效射流更加密集,且形成射流的头部最大速度及射流平均速度均大于单锥药型罩。通过因素影响分析结果可知,大、小锥罩角度的变化对射流头部速度影响均显著,且大、小锥罩角度差距越大,形成射流的平均速度越大,同时还能保持较高的射流头部速度。双锥罩罩顶距壳体起爆点距离越小,形成的射流头部最大速度越大,且侵彻深度越深;距起爆点越远,形成射流的平均速度越大,侵彻扩孔能力越强。     

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.     

Transient source current formulation for the analysis of arbitrarily shaped dielectric/conducting composite structures

In this paper, a novel time-domain integral equation (TDIE) approach is presented to analyze the transient electromagnetic response from three-dimensional dielectric/conducting composite structures. The composite bodies with different materials and conductor structures are considered as autonomous scattering objects. The scattered electromagnetic field is derived by superposition of the individual scatterers. The principal method is based on the application of electric and magnetic field boundary conditions on the surfaces of dielectric and conducting objects while considering the electric currents as unknowns. Triangular patches as well as quadrangular patches model the surfaces of the combined structure. The scattered electromagnetic fields inside and outside the combined structure depend only on the electric surface currents. This improves the post-processing time and complexity as compared with other methods using both equivalent electric and magnetic surface currents. To solve the resultant integral equations, the implicit method of moments is used. In our approach, the internal fields are independent of external currents and vice-versa, reducing the number of the matrix elements by considering them as zero.     

Topographic error analysis of a gear plunge shaving cutter finished by a cone grinding wheel

Abstract

Gear shaving is one of the most efficient and economical ways to finish gears roughed by hobbing or shaping. The theoretical pitch surface of a gear plunge‐shaving cutter is a hyperboloid with hollow tooth form. The tooth profile of a plunge shaving cutter is usually ground by a cone grinding wheel. In this paper, we propose a mathematical model to calculate the topographical error of the tooth surface of a ground plunge‐shaving cutter compared with the theoretical tooth surface that is conjugated with the work gear. The proposed mathematical model can be used to calculate the profile data of the cone grinding wheel and the corresponding machine setup at a predetermined operating pitch cylinder. The topographic error sensitivities of the plunge‐shaving cutter due to varied operating pitch cylinder, helix angle, and grind wheel data are discussed based on the proposed mathematical model. This paper provides approximate guidance for choosing the proper operation cylinder, the helix angle, and the geometrical data of the cone grinding wheel for the finishing or resharpening of the plunge shaving cutter.     

Continuous control of tapering in details shaped on circular grinding machines

Measurement Techniques -     

粉末药型罩聚能射流形成过程中温度分布及影响分析

根据石油射孔弹的实际结构和几何尺寸,运用ANSYS/LS-DYNA-2D非线性动力学有限元分析软件,采用瞬态非线性的热耦合计算方式,对孔隙率为11.53%的铜药型罩射流形成过程中典型瞬态的温度场进行描述和分析;对多孔药型罩聚能射流的最高温度-时间曲线进行研究,并对射流自身是否产生熔化进行判断;对比了多孔药型罩与密实药型罩聚能射流轴线和外表面温度。结果表明:聚能射流轴线温度高,由轴线向外表面逐渐降低,最高温度先增大,11μs增到最大1 743K后减小,最后几乎不变,约为1 378K,多孔药型罩比密实药型罩聚能射流的温度高,延伸性能和稳定性能更好。     

粉末药型罩聚能射流形成过程中温度分布及影响分析

根据石油射孔弹的实际结构和几何尺寸,运用ANSYS/LS-DYNA-2D非线性动力学有限元分析软件,采用瞬态非线性的热耦合计算方式,对孔隙率为11.53%的铜药型罩射流形成过程中典型瞬态的温度场进行描述和分析;对多孔药型罩聚能射流的最高温度-时间曲线进行研究,并对射流自身是否产生熔化进行判断;对比了多孔药型罩与密实药型罩聚能射流轴线和外表面温度。结果表明:聚能射流轴线温度高,由轴线向外表面逐渐降低,最高温度先增大,11μs增到最大1 743K后减小,最后几乎不变,约为1 378K,多孔药型罩比密实药型罩聚能射流的温度高,延伸性能和稳定性能更好。     

Investigations on the through-feed centreless grinding process

This paper reports the results of an experimental programme to study the effect of process parameters on the surface finish and out-of-roundness error on parts produced by the through-feed centreless grinding process. Experiments have been planned based on the statistical response surface methodology (RSM) technique. Mathematical models correlating the process parameters to the process responses are obtained. In conclusion, optimal process conditions to minimize the out-of-roundness error and to improve the surface finish on parts are reported.     

Lifetime increase method of cutting ability of grinding wheels in the process of magnesium alloy grinding

Im Artikel wurde ein neues Verfahren zum Schleifen von Magnesiumlegierungen mit Hilfe von keramischen Schleifscheiben dargestellt. Bei dieser Methode wurde ein neues Verfahren zur Konditionierung der aktiven Oberfläche der Schleifscheibe (Reinigung) angewendet. Es zeigte sich, dass dieses Verfahren die Schnittkapazität von Schleifscheiben um ein Vielfaches erhöht. Zusätzlich wurde die geometrische Struktur der Oberfläche nach dem Schleifen im 3D‐System bewertet und die darauf erzeugte diamantähnliche Schicht dargestellt.