浅析影响热磨机磨片齿形结构设计的主要因素

纤维板生产原料的纤维特性、热磨机的性能、磨片的制造工艺对磨片齿形的结构设计、纤维分离的机理及磨片综合性能等有不同程度的影响。     

热磨机磨片齿形结构的设计及静力学分析

热磨机磨片的齿形结构是磨片和原料间传递能量的主要方式,它与木片原料被研磨时的运动状态和研磨时间,以及纤维制备过程中纤维质量和设备的能耗密切相关。笔者根据磨片破碎区、粗磨区、精磨区的齿形结构、磨齿倾角、周向齿等参数对纤维分离能耗的影响以及磨片的设计要求,设计了一种有利于降低纤维分离能耗的热磨机磨片,并运用ABAQUS软件对磨片进行了静力学分析,分析结果表明磨片受到的静力作用对自身影响很小,设计满足要求。     

热磨机磨片齿刃比负荷对木纤维形态的影响

选择8种热磨机磨片,通过计算齿刃比负荷(SEL),并测量其加工纤维样本的长度及长径比,采用线性回归方法建立磨片齿刃比负荷与纤维长度、长径比之间的关联模型。分析结果表明,磨片齿刃比负荷对纤维长度和长径比有显著影响,均为负相关关系,其中对纤维长度的影响更为明显。这一特征可为生产中纤维形态质量预估、热磨机磨片选型及齿形结构设计提供参考。     

蒙特卡罗法在热磨机磨片优化设计中的应用

热磨机磨片生产加工木纤维的工作环境十分复杂,影响其齿形结构设计的因素较多,用传统的方法优化设计具有一定的局限性,而蒙特卡罗方法在优化设计方面具有极大的优越性。首先对其算法原理进行初步的研究,然后将其应用到热磨机磨片的优化设计中,设计出符合实际生产需求的磨片。     

热磨法纤维分离能量耗散影响因素的分析

目前,我国纤维板生产进入了一个高速发展的时期,年产量位居世界首位,而生产状况总体上呈现"高能耗、低效率"的状态,其主要原因在于我国纤维板生产的工艺水平和技术水平还比较落后,对纤维板生产的工程应用性基础理论的研究还存在不足,因此笔者结合热磨法纤维分离的基本原理及纤维制备的工艺过程,从热磨机磨片和热磨工艺参数两个方面对热磨法纤维分离能耗进行分析,分别探索磨片齿形结构参数、原料预处理工艺等因素对纤维分离能耗的影响,从而揭示热磨法纤维制备中能量耗散的影响因素,建立磨片齿形结构参数与纤维分离能耗之间的内在联系,不仅可以为纤维分离设备的结构优化、提高纤维分离质量以及降低纤维分离能耗提供可靠的理论基础和技术支撑,也可以提高磨片的使用性能。     

热磨机磨片的材质与磨损

热磨法(TMT)是目前国内外纤维板生产中分离纤维的主要方法,作为对纤维直接起研磨作用的热磨机磨片的质量优劣,关系整个热磨工程系统技术性能的发挥,能耗的大小,效率的高低等,因此,许多国家十分重视磨片的研究工作。     

热磨机磨片间隙电液伺服控制原理与系统设计研究

通过对典型热磨机磨片间隙控制系统的功能分析,采用电液伺服系统对热磨机磨片间隙控制系统进行了原理与系统结构设计,建立了控制系统的传递函数与数学模型,对液压缸和伺服阀进行了设计计算与选型;通过对系统传递函数的校正,保证了系统的稳定性和较好的控制品质。热磨机磨片间隙电液伺服控制系统的设计研究有助于提高热磨机的解纤质量和工作性能,具有理论和实际应用价值。     

扇块分区热磨机磨片的热应力分析与优化设计

通过对扇块分区热磨机磨片进行热应力分析,得到磨片的最大应力值和最大变形,并运用ANSYS的优化模块对磨片进行结构优化设计,得到了能够满足各项性能要求的新磨片,并最终达到了产品设计的轻量化要求.     

圆环分区直齿热磨机磨片的温度场和热变形分析

基于摩擦学理论和传热学,利用ANSYS建立圆环分区直齿热磨机磨片的稳态温度场和热变形的三维热分析有限元模型,分析该磨片处于热平衡状态下的温升和热变形.结果表明,热变形对磨片之间间隙有一定影响.     

动、静磨片盘的间隙在热磨机上的重要性

热磨机是生产中密度纤维板的主要设备,随着人造板在日常生活中的需求不断扩大,人们对它的质量要求也越来越高。磨片是热磨机的配套产品,磨片相当于机床上的刀具,在热磨机上起着不可轻视的作用, 它的应用适当与否直接影响人造板的质量。从几家人造板生产厂对磨片反馈的情况看,普遍认为有以下几种情况:磨机功耗大;纤维状态(纤维板组成单元)不稳定;磨片损坏快等。针对这些问题,我们前往生产厂家实地考察,并认真讨论,查阅资料,深入分析,还咨询了有关国外磨机专家,一致认为出现上述问题的原因是由于动、静磨片盘间隙调整不当所致。笔者从以下几个方面加以分析说明:     

纤维板热磨机磨片材质开发与研究

Defibrator is a very important machine in the wood industry for producing fiberboard.The refiner plates are the key parts of defibrator that directly act with the wood,and broken easily.The working life of the refiner plates is of significance to the wood industry.It may affect refining quality,production efficiency,and power consumption.In this paper,the abrasion resistance of the refiner plate made of different materials,the stainless steels and high chromium cast irons,were tested and compared.The results showed that abrasion resistance of refiner plate made of high chromium cast irons was better than that of the stainless steel materials.Although the two kinds of materials have the same compositions,their abrasion resistances have apparent difference.The main reason is that the material microstructures have very important effects on their performance.The refiner plates made of developed high chromium cast irons don‘t demand the complex heat treatment.This can simplify the producing process,save the cost of production,decrease labor strength,and increase the production efficiency.     

开放式实验热磨机功能分析与结构设计

结合实验热磨机的功能与设计要求,对开放式实验热磨机的各组成部分及主要结构进行了功能分析与设计.开放式实验热磨机的主要特点是既可满足研究纤维分离机理所需,又可满足研究纤维分离设备结构优化的要求.该机的设计与研制为国内研究纤维分离机理及纤维分离设备性能提供了一个实验平台,对提高国内该领域的研究水平与促进技术进步具有积极作用和现实意义.     

Water sorption,surface structure and surface energy characteristics of wood composite fibres refined at different pressures

During fibre processing, wood fibres are subjected to a range of physical and chemical conditions sufficient to slightly alter their chemical composition and hence their ultimate performance when used in the manufacture of wood fibre-based composites. In order to better understand the effects of refiner conditions on material performance, wood fibres were subjected to processing at different refiner pressures (4, 6, 8 and 10 bar) and subsequently dried in a flash drier. The fibres were analysed for changes in surface area, surface energy, surface structure and water vapour sorption characteristics. The methods applied were nitrogen adsorption utilising the Brunauer–Emmett–Teller theory, inverse gas chromatography, scanning electron microscopy and dynamic vapour sorption. It was found that increasing refiner pressure resulted in fibres of lower surface area, accompanied by increasing dispersive surface energies up to operating refiner pressures of 8 bar. It was found with fibres refined at different pressures that as the refiner pressure increased the equilibrium moisture content of the fibre decreased at the set relative humidities. However, it was also noted that the hysteresis was not significantly different between each of the refiner pressures. The results suggest that different refiner pressures can be used to tune the surface characteristics which may be beneficial to product development and the improvement of the environmental profile of the wood fibre composites.     

一种新型磨盘成形技术研究

本文研究了如何运用计算机技术三维制模、采用覆膜砂造型、优化合金材料和利用计算机来控制打箱时间等新工艺来生产磨盘。结果证明:利用计算机技术能减少制模时间,提高产品的适应度;同时精密成形能减少磨盘的废品率;优化合金材料和控制好打箱时间来消除淬火热处理阶段。与传统的工艺相比采用这些改进措施,磨盘的制造工艺有增强韧性、提高铸件精度、消除热处理阶段和提高生产效益等几方面的优点。图5表4参6。     

热磨制浆系统远程监测及故障诊断专家系统

为了实现对生产现场热磨制浆系统的有效检测，提前预防设备故障的发生，开发了热磨制浆系统远程在线监测及故障诊断专家系统。该系统将计算机技术、传感器技术、通信技术、数据库技术与设备诊断技术相结合，以可编程序控制器（PLC）和InTouch10．1组态软件为开发平台，对热磨制浆系统现场的各项参数进行采集、分析和实时反馈。运用关系型数据库系统SQLServer和CLIPS专家系统工具建立相应的故障诊断规则，实现热磨制浆系统远程监测及故障诊断专家系统的设计，提高了热磨制浆系统运行的安全系数和对故障的分析能力，可满足用户对在线检测及故障诊断的需求。     

Development of a joint system using a compressed wooden fastener I: evaluation of pull-out and rotation performance for a column—sill joint

Compressed wooden plates and dowels were used to connect members in post-and-beam structures as a substitute for a steel fastener. In order to take advantage of the characteristic properties of compressed wood and to achieve optimum joint performance, two compressed wooden plates were used in each joint to give multiple shear planes for each compressed wooden dowel. Consequently, this type of joint showed very good properties in pull-out and momen-trotation performance, and its engineering design could be further optimized. This joint is expected to be introduced to many kinds of structural systems, including long-span frame structures made of domestic timber found in Japanese residential houses.     

空心胶合木-钢插板螺栓节点承载力试验研究

为研究空心胶合木-钢插板螺栓连接节点承载力及延性性能,探讨了不同胶合木宽度和螺栓直径对破坏模式的影响,分析了不同宽径比、承压宽度对节点承载力、延性等的影响。结果表明:增加宽径比及承压宽度,可有效提高节点延性。宽径比12.5~16.4的节点延性较佳;宽径比10.0~10.9是单、双塑性铰破坏模式的临界点,可作为工程设计参考值。     

Lateral performance of a semi-rigid timber frame structure: theoretical analysis and experimental study

Semi-rigidness of the joint connections is one of the main characteristics of timber structures. The pin-joint assumption for the semi-rigid joint connections might be not conservative in the timber structural design. In this paper, structural analysis was conducted on a semi-rigid timber portal frame; the formulas were derived in terms of the internal force and the lateral stiffness, and the influence of the semi-rigid connections was discussed. Moreover, experimental tests were performed on three full-scale timber portal frames and five bolted timber connections to study the lateral performance of the frames and the moment resistance of the connections. For consistency, the connections from the portal frames and the connections for bending tests were of the same configuration. Finally, a calculation flowchart of the lateral performance on a semi-rigid frame was presented to verify the derived formulas and to show a framework of the lateral structural design process.