人造板热压方法比较分析

人造板的热压方法根据其生产方式可分为平压法、辊压法和挤压法;根据加热板坯的方式又可分为接触加热、高频加热、接触高频混合加热;根据板坯在热压设备中的运行情况还可分为连续式热压和周期式热压。本文对目前应用较为普遍的、采用接触加热的平压法和辊压法的工作原理、工艺流程、设备特点及性能、经济性能和产品性能等进行了比较分析,以期为企业设备选型提供参考依据。     

竹材重组材高频加热胶合成型压机研制及应用

在分析当前竹材重组材生产方法及设备的基础上,提出了高频加热胶合成型方法。重点介绍了高频加热胶合成型机的主要参数设计、高频发生器参数设计,最后简单介绍了高频加热胶合工艺及用该设备生产的竹材重组材的物理力学性能。     

高频介质加热技术在木材工业中的应用

高频介质加热技术是近几十年来发展起来的一门新技术。它是利用快速变化的高频电磁场对物体进行作用而使其内部发热达到加热的目的,因而具有加热速度快,加热均匀,产品质量等优点。目前,高频加热在木材工业中主要用于木材胶合和木材干燥。本文主要概述了高频热的原理与特点、木材高频加热的种类与应用技术。     

高频介质封边机组的试制

高频介质加热技术已在木材加工行业推广应用,并取得一定效果。但是,将高频介质设备用在板式家具生产流水线还是首次。遵照伟大领袖毛主席关于要把国民经济搞上去的伟大教导,我厂组成三结合会战小组,迅速上马板式家具生产流水线,并在完成封边机组的同时,基本上完成了五板(板式衣柜之柜门二栅、旁身二栅、中身一栅) 连成一条线。一、工作原理高频介质封边机组系采用高频介质加热技术与机械传动相结合完成板式衣柜五栅板的涂胶、封边(胶合)、倒楞、砂光等几道工艺。其中封边(胶合) 是板式衣柜生产线中的关     

木质复合材高频加热胶合过程温升的测量

高频介质加热是在频率范围为几兆赫到几百兆赫的高频电场作用下,被加热介质中的分子按电场作用方向取向从电场中获得能量,在高频电场作用下,介质分子反复激烈的运动,从而使分子间的摩擦变得剧烈,这样就把从电场中所吸收的能量转化成热量,达到介质加热的目的.     

木制品生产中调频加热设备工作电容的绝缘问题及解决措施

１现状与存在的问题高频介质加热技术是一项应用较为广泛的新技术,在金属焊接、淬火、塑料热合、农产品加热、烘干等方面已有广泛的应用。由于高频介质加热具有胶合速度快、加工质量好、加热有选择性、加热过程容易控制、加工周期短、操作过程简单等优点,从８０年代开始...     

纪元公司的追求

石家庄开发区纪元电气有限公司于１９９３年在河北石家庄高新技术产业开发区注册，属民营科技企业。１９９５年通过河北省科委认定的“高新技术企业”资质。 纪元公司从成立至今一直从事机电一体化高频介质加热设备的研制与开发工作。先后开发并生产了多种用于木材加工的高频加热木工机械，产品销往全国２０多个省、市、自治区的上百个家具及木材加工企业。特别是高频弯曲木系列液压机组，为我国弯曲木家具的发展起到了重要的推动作用，产品至今畅销不衰，成为公司的支柱产品。目前公司的产品已经有七八个成熟的品种，几十个规格系列。而且…     

浅谈高频加热在木材胶合中的应用

高频介质加热技术是近三十年来发展起来的一门新技术。它的基本原理是利用高频电场对物质内部分子的反复极化,使分子在这种高频交变电场作用下急剧运动而相互摩擦产生热,从而达到加热的目的。由于它的热量是由内向外传递的,具有加热速度快、加热均匀、加热有选择性、产品质量好等优点,因此应用越来越广。在木材加工中,高频介质加热主要用于木材胶合(如胶接、胶拼、封边、胶合成型、胶合空芯或蜂窝板、家具组合装配胶合、层积材胶合、胶合板以     

高频热压下刨花板的温度场

近几年来,高频介质加热的方式在刨花板生产中获得了应用。同时辅以上、下压板用热油加热,从而缩短了每块板坯的热压时间。同时,高频介质加热能使板坯均匀受热,避免了传导加热时,在较长时间内板坯中心部位温度低,而板坯的上下板面温度高,使板坯表层较芯层固化快,从而影响刨花板的质量。因此,采用高频介质热压刨花板可提高刨花板的物理力学性能。本文是将含热源瞬态导热偏微分方程用于求解高频热压下刨花板的温度场,并对刨花板板坯内所含水份在加热时发生相变的温度场做了理论分析,给出用差分法的计算机解法,以求得到的温度场更接近实际情况。文内还针对一个具体的刨花板高频热压情况的参数,给出计算结果。旨在求解刨花板板坯在高频热压下的温度场,为刨花板的高频热压工艺设计提供了依据。     

用水杉和池杉材作芯板生产细木工板的研究

在实验室条件下，实用水杉材和池杉材为原料，脲醛树脂胶为胶粘剂，高频介质加热为热源，研究了速生树种工业利用的新途径——细木工板生产技术。研究结果表明，以水杉材和地杉材为芯板原料生产细木工板是完全可行的，所采用的高频加热工艺是合理的；细木工板的物理力学性能超过国家标准规定的指标值。     

木材微波干燥缺陷产生原因及其预防措施分析

从木材介电特性、微波穿透深度、微波设备、干燥工艺等方面分析了木材微波干燥缺陷产生的主要原因,并从优化干燥器设计,改善微波场分布均匀性,控制微波辐射功率和辐射时间,改变微波辐射方式等方面探讨了预防干燥缺陷产生的主要措施,以期为木材微波干燥技术的研究和应用提供参考。     

木材微波加热厚度的确定

较之传统加热方法,微波加热是一种新型加热技术,在简述木材微波加热的机理上,阐述了影响木材介电特性的因素,指出其中木材含水率和温度是影响木材节电性质的两个最重要的因素.通过理论计算确定微波在木材中的穿透深度.计算表明:随着木材含水率和微波工作频率的增加,微波在木材中的穿透深度减少;当用频率为915 MH z和2 450 MH z的微波加热或干燥具有高含水率的木材时,木材的最大厚度应分别控制在16 cm和6 cm左右.     

推行集中供热设备标准化、系统化管理的探讨

针对集中供热设备标准化、系统化管理,提出了建议与探讨,能更好的满足节能减排和优化城市环境的要求。     

Wood dielectric loss factor prediction with artificial neural networks

An artificial neural network that can predict the dielectric properties of wood was developed and tested with experimental data. The network was capable of accurately predicting the loss factor of two wood species not only as a function of ambient electro-thermal conditions but also as a function of basic wood chemistry. This way, an important predictive tool is created that allows optimization of dielectric heating and drying for many wood species without significant experimentation should their chemical composition be known under variable temperatures, moisture contents and electric filed characteristics.     

我国暖通、空调系统设备的发展趋势

我国空调设备具有多样性和复杂性,应在空调冷源、空气处理设备、空调末端产品、控制系统、机房专用机、家用空调、通风设备等方面开发新技术,新产品,在引进和消化国外技术的基础上,大力保护和发展民族产业。供热设备应开发适用性广的散热器,发展低温地板辐射供热方式和远红外辐射供热设备,研制适合中国国情的热计量手段。     

Mass and heat transfer mechanism in wood during radio frequency/vacuum drying and numerical analysis

The mass and heat transfer mechanisms during radio frequency/vacuum(RF/V) drying of square-edged timber were analyzed and discussed in detail, and a new one-dimensional mathematical model to describe the transport phenomena of mass and heat during continuous RF/V drying was derived from conservation equations based on the mass and heat transfer theory of porous materials. The new model provided a relatively fast and efficient way to simulate vacuum drying behavior assisted by dielectric heating. Its advantages compared with the conventional models include:(1) Each independent variable has a separate control equation and is solved independently by converting the partial differential equation into a difference equation with the finite volume method;(2) The calculated data from different parts of the specimen can be displayed in the evolution curves, and the change law of the parameters can be better described. After analyzing the calculated results, most of the important phenomena observed during RF/V drying were adequately described by this model.     

Applicability of effective medium theory to wood density measurements using terahertz time-domain spectroscopy

The use of an effective medium theory is important when accurately measuring wood density using millimeter and terahertz wave techniques. To confirm the applicability of this theory to the evaluation of wood density, the relative permittivity and dielectric loss of oven-dry flat-sawn specimens of 11 different wood species were measured in a frequency range of 0.15–1.2 THz using a transmission measurement system for terahertz time-domain spectroscopy. A mixture model based on the effective medium theory well explained the density dependence of relative permittivity over the entire frequency range, while it did not fully explain that of dielectric loss, especially for higher frequencies. This indicates that wood scatters the terahertz wave with a wavelength close to the transverse sectional dimensions of the pores in wood in the same way as Mie scattering. It was found from the dielectric loss spectrum of wood substance that the frequency around 0.23 THz was preferable for the nondestructive evaluation of wood.     

根河体育馆采暖通风设计

根河地处东北地区北端,夏季时间短,早晚温差大,体育馆设内的采暖通风设施基本可以满足人们需要。     

新型热风加热木材干燥窑

介绍炉气间接加热木材干燥中的一种新方法－－新型热风加热木材干燥，简述了窑体和干燥设备的组成，结构特点，工作原理及其所具有的造价低，质量可靠，安全，节能等优良特性，说明热风加热木材干燥窑是中、小型木才加工厂较为理想的干燥设备。     

Thermal-death kinetics of the bark beetle (Dendroctonus armandi; Coleoptera: Scolytidae)

Data on thermal-death kinetics of bark beetles are essential to develop phytosanitary heat treatments for pine wood and pine wood packaging materials. Using a heating block system, effects of different heating rates between 44 and 50°C at 2°C intervals on destruction of Dendroctonus armandi adult insect were examined. Heat resistance of the insects was found to increase at low heating rates (0.1 or 0.5°C/min). Therefore, the thermal-death kinetics of the beetles were determined at a high heating rate of 5.0°C/min which simulated the rapid dielectric heating of wood products. Results showed that the thermal death curve of D. armandi followed a zero-order reaction kinetic model, indicating the heat destruction rate of the beetle at different treatment temperatures to be independent of their population size. The required thermal holding times to result in destruction of the entire population were 40, 8, 4, and 2?min at 44°C, 46°C, 48°C, and 50°C, respectively. The evaluated thermal-death kinetic data are useful in developing effective beetle elimination quarantine protocols for the wood. A 50°C ?2?min heat treatment with a heating rate of ～5°C/min can be effectively used for disinfesting bark wood materials.