陶瓷内应力影响因素及软测量系统研究

本文从流变学理论及泥料在真空练泥机中的运动特性出发,分析了陶瓷墙地砖挤压成型生产中造成泥料内应力分布不均的原因及各种影响因素.根据分析结果,提出了基于真空练泥机机头内壁压力来间接测量陶瓷坯泥内应力的方法.使用神经网络来建立机头内壁压力与坯体内应力的模型,并以LabVIEW为平台搭建了整个软测量系统,实现了坯体内应力的在线测量.     

细瓷工业中的盘类生产

内施茨厂的盘类自动作业线备有坯泥自动喂料机,机内的坯泥由坯泥存放带进给,坯泥来自原料制备车间的真空练泥机。坯泥自动喂料机为一部双蜗杆真空练泥机,练成的泥条连续不断地从练泥机咀出来。每根蜗杆可各自起动。泥条切成规定大小的泥段,并放在两条泥段输送带上。泥条由于经过二次真空练泥,就提高了坯泥的质量。工人将泥段放在切泥台上切成泥饼,再放在泥饼输送带上。     

连续螺旋绞刀参数对挤出过程中泥料特性的影响

以TL-125B型真空练泥机连续螺旋绞刀部件为研究对象,运用ANSYS软件建立了泥料在连续螺旋绞刀中挤出的几何模型,用实测的泥料流变参数及螺槽进出口压力进行定义和加载,对挤出过程中泥料的速度场、压力场进行模拟,对影响挤出过程中坯体质量的连续螺旋绞刀工况和结构参数进行了研究.利用数值模拟结合正交试验法对轴毂半径、连续螺旋绞刀的螺距、转速、刀片厚度进行了优化设计,得出了泥料在挤出过程中速度、压力分布情况,以及真空练泥机在不同的连续螺旋绞刀结构参数下对泥料的生产能力、质量的影响.     

真空练泥机的挤泥装置对泥料质量的影响

１前言真空练泥机的挤泥装置能促使陶瓷泥料搅拌,揉练及混合均匀,因此陶瓷泥料经真空练泥机处理后,其物料分布趋于均匀、结构更为紧密,可塑性得到提高,并成为具有一定形状尺寸能够制造产品的泥段。研究和探讨真空练泥机挤泥装置的构造及其对泥料的作用,对于提高泥料...     

基于有限元方法的真空练泥机螺旋绞刀结构参数研究

通过把真空练泥机的筒体及螺槽简化成2平行平面,采用不同的轴毂半径和节距尺寸,建立泥料在螺槽中运动的三维几何模型,在“动绞刀,静筒壁”的假设条件下,确定边界条件,运用有限元软件ANSYS,从数值模拟的角度来研究真空练泥机螺旋绞刀的轴毂半径、节距尺寸对泥料运动特性的影响,为真空练泥机的设计制造提供了理论依据,为改善挤出泥段的质量,最终提高可塑法成形陶瓷坯体的质量提供理论参考。     

泥料在螺旋绞刀中的流场特性研究

以TCMD125A型真空练泥机变螺距、变槽深连续螺旋绞刀部分为研究对象,建立了泥料在绞刀中挤出的几何模型,并进行数值模拟.分析了陶瓷泥料在挤出过程中的运动机理,对泥料挤出过程中速度、压力分布情况作了详细的分析.     

基于ANSYS变温场的真空练泥机泥料挤出质量的研究

应用ANSYS软件对真空练泥机挤出过程中陶瓷泥料的温度场进行分析,通过对在不同摩擦系数、不同外界温度、给泥料加热到不同温度等热参数下的运动泥料进行数值模拟,得出了泥料在热参数的影响下螺旋槽内的温度变化规律.结果表明泥料在挤出过程中由于温度的变化引起速度和压力变化,从而影响泥料在挤出过程中的流动质量,为陶瓷用真空练泥机泥料挤出生产的研究提供了理论依据.     

对消除陶瓷制品内机械应力的研究

众所周知,有三种应力导致陶瓷坯体变形或制品龟裂,即由温度梯度造成的热应力,由石英多晶转变造成的结构应力和由内部缺陷造成的机械应力。本文主要对机械应力引起的变形进行研究。一、泥料呈左旋S型走向问题泥料刚离开搅龙时,泥料呈左旋S型走向,在进入机头后,被重新挤压致密。当泥料中有S型应力时,在湿坯或干燥时并不明     

试论真空练泥机与泥段质量的关系

真空练泥机(以下简称练泥机)是电瓷工业和陶瓷工业的重要机械设备。泥料经练泥机加工后,其水分和组分趋于均匀,结构更为致密,可塑性得到提高,并可成为制造产品的泥段。国内外生产实践表明,泥段质量的好坏,与练泥机的规恪型式,结构和性能是密切相关的。下面重点探讨在电瓷生产中,练泥机与泥段质量的关系,达到提高泥段质量和提高产品质量的目的。 1 练泥机的型式和规格与泥段质量的关系 1.1 练泥机的型式与泥段质量的关系练泥机的型式大致可分为立式练泥机和卧式练泥机两大类,以轴而论,练泥机又有单轴和多轴之分。卧式多轴练泥机是电瓷生产中运用最广泛的一种练泥机,主要用来挤制量大面广的中小产品的泥段。选用卧式练泥机来挤制中小产品的泥段,主要是出于以下两点考虑:一是卧式练泥机机身低、操作简便、一般不配置辅助操作机械,工人多为手工操作;二是中小     

基于ANSYS变温场的真空练泥机泥料挤出质量的研究

应用ANSYS软件对真空练泥机挤出过程中陶瓷泥料的温度场进行分析,通过对在不同摩擦系数、不同外界温度、给泥料加热到不同温度等热参数下的运动泥料进行数值模拟,得出了泥料在热参数的影响下螺旋槽内的温度变化规律。结果表明泥料在挤出过程中由于温度的变化引起速度和压力变化,从而影响泥料在挤出过程中流动质量,为陶瓷用真空练泥机泥料挤出生产的研究提供了理论依据。     

Using Rheology to Achieve Co-Extrusion of Cement-Based Materials with Graded Cellular Structures

Co-extrusion involves simultaneous extrusion of multiple layers and can be used to produce functionally graded materials whose layers have different properties. Rheological control is vital for successful co-extrusion. During extrusion, flow in the barrel and die land in a ram extruder should be plug-like, while the paste should be sheared and uniformly elongated in the die entry region. In the barrel of the extruder, the paste flow velocity field was inferred by direct observation of the paste left in the barrel, and evidence for plug flow in the barrel was seen only at low-extrudate velocities. In the die land, the Benbow nonlinear model was employed to assess the paste flow behavior, and plug flow was achieved only when the shear stress applied to the paste by the die land wall was smaller than its yield stress. For co-extrusion, a simple method using thin-walled tubes was found to be effective to prepare layered feedrods. Functionally graded cellular structures of cement-based materials were successfully co-extruded by using a low-extrudate velocity when the paste had decreasing shear viscosity from inner to outer layers.     

Approximate flow analysis of paste forming process for simplified ceramic dome

Abstract

The types of flow obtained during the formation of hemispherical domes are difficult to analyse. The aim in the present paper is to model ceramic paste flows in a press moulded ceramic dome with a simplified ‘top hat’ shape. The simplified process can be separated into a number of flows, each of which can be analysed easily. The rheological behaviour of ceramic paste in these flows is usually difficult to determine, since the materials are neither homogenous nor simple fluids. Models are presented to characterise the flows and validate them experimentally. Theoretical predictions are in good agreement with the experimental data.     

φ3.2m×13m高细磨磨内结构的改进

介绍了一种与辊压机配套的3.2m×13m高细磨的磨内结构,产量达100t/h,最高达115t/h。与传统高细磨管磨机的磨内结构进行了对比,分析了传统高细磨磨内结构配套辊压机后的不适应性。本磨机的回转内部结构解决了3.2m×13m高细磨配辊压机的工艺系统台时产量低、磨内温度高、堵料频繁的问题,提高了生产效率,降低了能源消耗,能为企业带来更大的经济效益。     

陶瓷辊棒的螺旋挤出成型

介绍了陶恣辊棒的常用成型方法及螺旋挤出成型的生产工艺，并详细地论述了真空挤管机的结构特点及其对陶恣辊棒的螺旋挤出成型生产方式所产生的优越性。     

大规格球磨机球磨釉料的探讨

8吨球磨机应用氧化铝刚玉质异形砖与普通瓷质砖砌筑成具有过渡圆角及不连续螺旋的新结构内衬（以下简称为新内衬），在广东某大型企业的生产线上球磨陶瓷耐磨地砖釉料，并就釉料颗粒大小及粒度分布、电耗、介质磨耗等与1．5吨球磨机进行对比，进行了实验研究。结果表明：配有新内衬的8吨球磨机可磨出颗粒较小、粒度分布较窄的质量好的釉料，且具有好的经济效益；在墙地砖大批量生产的条件下，采用新内衬的8吨等大规格球磨机替代1．5吨球磨机球磨普通釉料切实可行。     

蜂窝陶瓷练泥机链传动失效分析及改进措施

针对混料练泥机链传动时有失效的情况，运用可靠性设计理论对其进行分析研究，找出了链传动因可靠度不足而失效的原因，并提出了解决问题的措施。     

Research on the micro-extrusion characteristic of mini-screw in the screw extruding spray head

Extrusion production capacity is a chief factor of measuring how good the extruding spray head of Fused Deposition Modeling (FDM) is. The main geometrical parameters of screw and barrel (the active length of screw, the diameter of screw, the helix angle, the width of screw arris, the depth of screw channel, the clearance between screw, and barrel, etc.,) and the processing parameters such as screw speed, the pressure of nozzle are closely related to extrusion production capacity. In this article, the spray head is designed to be a special mini-screw extruding spray head and the mini-screw is different from common screw. The characteristics of the mini-screw in the research are that it is small in size, with narrow screw channel and wide screw arris structurally. Based on hydrodynamics and melt conveying theory, the micro-extrusion characteristics of mini-screw used in the screw extruding spray head of FDM were discussed in detail in this article. The relationship between extrusion production capacity and the main geometrical parameters of screw and barrel and the processing parameters is researched. Theoretical analysis was performed to find out the quantitative relationships between production capacity of extrusion and main parameters (the screw speed, main geometrical size of screw, the clearance between screw and barrel, and the pressure of nozzle, etc.,) so that the theoretical guidance on the design of spray head with mini-screw could be provided. The characteristic curves of mini-screw and nozzle are analyzed to find out the jointed work point of spray head. The main factors influencing extrusion capacity of nozzle are discussed in this article. Furthermore, the development of FDM will be promoted and the micro-extrusion theory would be more perfect by the research.     

新型螺杆挤出机熔体输送理论的研究

介绍了一种新型嵌套式螺杆挤出机。对熔体输送段进行了深入分析，把内螺杆的运动等效为螺杆轴的反向拖曳和螺棱的正向推力置换两部分作用，建立了对应的物理模型和数学模型，并得到了解析解。重点讨论了沿螺槽方向的流动和横向流动，并与普通单螺杆挤出机作对比，得到了螺杆和机筒同时旋转情况下的体积流率。结果表明，所建模型的解析解和文献中的实验数据较为吻合，当螺杆和机筒同时旋转时，熔体输送段的体积流率大大增加，横向流动和平行平板模型类似。     

Behaviour of different industrial ceramic pastes in extrusion process

Abstract

It is well known that the extrudability of a ceramic paste is strongly dependent on materials composition and formulation, basically because it controls the resulting plasticity. Accordingly, the characterisation of the plastic behaviour is essential to adjust the fluxing properties of the material. In the current work, three industrially prepared ceramic pastes (porcelain, earthenware and terracotta) were tested, using stress–deformation curves obtained by compression of cylindrical probe tests. To achieve good extrusion performance, the design and operating conditions also need to be considered in detail.

The ram extrusion of adjusted pastes was followed by the Benbow–Bridgwater model. Differences in the flow behaviour were related with stress–deformation curves and with the surface quality of the extrudate (by using the static friction coefficient).     

Effects of Additives on the Interfacial Microstructure of Cofired Electrode-Ceramic Multilayer Systems

An investigation of the cofired behavior between silver/palladium electrode paste and lead-based relaxor ferroelectric ceramics demonstrated that mismatched sintering shrinkage was caused by differential sintering kinetics. Improvement of the cofired characteristics was obtained by adding different ceramic powders into the electrode paste. The sintering kinetics analyses show that the roles of ceramic additives lie in changing the densification mechanism of the silver/palladium electrode paste. Scanning electron microscopy observations indicate that ceramic additives apparently improve the interfacial bonding by the formation of chemical reaction layers. Compared to BaTiO₃-based ceramic additives, which are caused by palladium-lead-based reactions analyzed from the X-ray diffraction spectrum, lead-based perovskite additives will degrade the electronic properties and decrease the melting point of the silver/palladium electrode to a certain extent. Criteria for choosing ceramic additives have been proposed in this paper.