谈木家具生产成本的控制

就木家具生产的全过程,从产品设计、材料供应和产品加工3个方面论述木家具生产成本的控制。     

Efficacy of radio frequency treatment and its potential for control of sapstain and wood decay fungi on red oak,poplar, and southern yellow pine wood species

The effectiveness of radio frequency (RF) treatment in the control of wood decay fungi (Gloeophyllum trabeum, Ganoderma lucidum, and Irpex lacteus) and sapstain fungus (Ceratocystis fimbriata) in red oak (Quercus spp.), poplar (Populus alba), and southern yellow pine (Pinus spp.) was evaluated in the laboratory as an alternative to methyl bromide (MB) treatment. Wood samples (15.5 x 10 x 10 cm) were inoculated with fungi from a 7-day culture by dipping them to a depth of one face deep (2 cm) into inoculum and incubating them at 25°C for 14 days. Identical wood samples were left uninoculated as controls. Subsequent to incubation, the wood blocks were exposed to RF radiation in an industrial 40-kW dielectric oven at temperatures between 60° and 70°C for 2 min. The test fungi were recovered and reisolated from all of the control wood blocks but not from RF-treated wood blocks. RF treatment resulted in complete inhibition of the fungus in 98%-100% of the wood samples. Moisture content loss (≥1%) was noted after wood had been exposed to RF treatment. Moisture content may be an important factor to consider with RF treatments. RF treatment can, therefore, potentially provide an effective and rapid quarantine treatment as an alternative to MB fumigation for certain pathogen-wood combinations. This article reports the results of research only. Mention of a product does not constitute an endorsement or recommendation by USDA for its use.     

Numerical and experimental analysis of a wood drying process

 Experimental investigation and computational analysis were performed to evaluate the influence of the ambient air parameters during the drying process on the temperature, moisture and resulting deformations and stresses in wood samples. The numerical procedure uses the Finite Volume Method to discretise the equations governing heat, mass and momentum balance and takes into account the anisotropic nature of wood. The comparison of the numerical and experimental results shows very good agreements, implying that the proposed numerical algorithm can be used as a useful tool in designing wood drying schedules. Received 31 March 1999     

沙棘木蠹蛾生物学习性及防治研究

沙棘木蠹蛾(Holcocelus vicarius walker)是目前沙棘林区主要蛀干害虫，造成沙棘大面积死亡。该虫2年1代跨3个年度。其防治方法主要用磷化铝堵塞虫孔熏杀幼虫，化学药剂喷杀初孵幼虫及灯诱、性诱、人工捕杀等实行综合治理，效果可达90％以上。文中还记述了沙棘两种主要蛀干害虫沙棘木蠹蛾与沙柳木蠹蛾在幼虫与成虫形态上的主要区别，便于在防治工作中的识别。     

Seasonal dynamics of wood formation: a comparison between pinning,microcoring and dendrometer measurements

Three different methods were evaluated for analysing wood formation of Norway spruce [Picea abies (L.) Karst.] and Scots pine (Pinus sylvestris L.) in Finland. During two growing seasons, wood formation dynamics were determined both by wounding the cambium with a needle followed by localisation of the wound-associated tissue modification after the growing season (pinning), and by extracting small increment cores during the growing season (microcoring). Stem radius was additionally monitored with band dendrometers. For Norway spruce, pinning and microcoring yielded similar dates for the onset of wood formation. The timing of wood production during the growing season was also similar for pinning and microcoring. For Scots pine, the onset of wood formation was recorded from microcores almost 2 weeks later than from pinning samples. In Scots pine, microcore measurements also produced somewhat later cessation dates for tracheid formation than the pinning samples. For both tree species, the total number of tracheids formed during the growing season was, however, about the same for pinning and microcoring. Dendrometer results clearly differed from those of pinning and microcoring. In particular, the dendrometers showed an increase of stem radius considerably earlier in spring, when the other methods did not detect wood formation. Thus, pinning and microcoring currently represent the most reliable techniques for detailed monitoring of wood formation.     

三通道刨花干燥机刨花干燥过程自动控制系统初探

文中对三通道刨花干燥机刨花干燥中被控对象的特性、过程控制的方法、检测仪表、调节控制器与调速系统进行了探索与研究。干燥机的热效率高、刨花终含水率均匀、形态好。     

A model of anisotropic swelling and shrinking process of wood

To elucidate the origin of the shrinking anisotropy of wood during the drying process, as well as to begin to gain an understanding of the interaction between the moisture and the cell wall components, the shrinking process of a single wood fiber regarding water desorption was simulated by using an analytical model which was developed in the previous report (Part 1). Resulting data were compared with the experimental ones in this paper. The following conclusions were obtained: (1) The matrix substance, as a skeleton in the secondary wall, tends to shrink isotropically. However, the cellulose microfibrils, as a rigid framework of the cell wall, almost did not shrink at all due to the water desorption. As result, wood shrinks anisotropically during a drying process. The microfibril angle in the S2 layer is one of the most important factors related to the degree of shrinking anisotropy of the wood while drying. (2) According to the simulation, the expansive strain caused in the matrix skeleton by the water sorption increases by 15% (= 150,000 micro-strains) from the oven-dried condition to the green condition. Based on this value, the moisture content at the fiber saturation point is calculated to be about 35%, which is close to the experimentally obtained one. These results give quantitative evidences that the hygroexpansion of the wood cell wall is controlled by the mechanism of the reinforced matrix hypothesis. Received: 28 July 1998     

Kinetics and FTIR characteristics of the pyrolysis process of poplar wood

The pyrolysis characteristics of residues of poplar (Populus sp.) wood were investigated using a thermogravimetric analyzer coupled with a Fourier transform infrared (TG-FTIR) spectrometer. The pyrolysis process was subdivided into four stages at a rate of 10℃·min-1 , varying from 30 to 650℃. Below 180℃, a mass loss occurred for drying and preheating the sample and the onset temperature of pyrolysis ranged between 180-260℃. A significant mass loss of 61.4 wt.% occurred between 260-380℃, followed by a slow and continuous mass change with lignin devolatilization. The analysis of kinetic reactions showed that the activation energy (78.29 kJ·mol-1 ) in the low-temperature section was much larger than that (6.40 kJ·mol-1 ) in the high-temperature section. The evolved gases formed by thermal degradation of poplar wood were simultaneously analyzed by FTIR. It was observed from the main peaks that the emissions evolved during poplar wood pyrolysis were acetic acid, carbon dioxide, carbon monoxide, methane, water, some volatile com- pounds of esters, alcohols and aldehydes. The emissions gradually increased with rising temperatures before a strong peak around 360℃ and then decreased. Most gaseous products were emitted in the 320-380℃ range, while CO2 was continuously emitted in a wide range from 140-550℃.     

Formation and deposition of pseudo-lignin on liquid-hot-water-treated wood during cooling process

Pseudo-lignin induced by high-severity dilute acid treatment of lignocellulose has been widely studied because of its detrimental effect on enzymatic hydrolysis. However, cooling-induced pseudo-lignin (CIPL) formed during the cooling process after treatment has always been ignored and never been characterized systematically. To investigate the formation and chemistry of CIPL, liquid hot water treatments of poplar wood were conducted. Samples of treated wood and hydrolysate were taken out from digester at various temperatures during the cooling process for characterization. SEM images evidenced a progressive deposition of CIPL on the surface of the treated wood during cooling process with a yield of 19.6 mg/g treated wood. However, the treated wood which was collected isothermally at reaction temperature showed no pseudo-lignin. Variation of organic compounds in hydrolysate from lignocellulose degradation during cooling process revealed that depolymerized lignin and furfural accounted for 80.4 and 10.6 % of CIPL, respectively, while soluble saccharides from carbohydrate hydrolysis were independent from CIPL formation. These findings stress the importance of isothermal separation of treated wood and hydrolysate. Otherwise, CIPL should hinder enzymatic hydrolysis for biofuels production or delignification for cellulosic fiber production.     

柳树重组复合材生产技术及质量控制

柳树重组复合材,是将柳树枝加工成柳枝丝束,通过模具,经冷压、高温固化而成的型材.制造工艺为:柳树枝碾压→丝束干燥→树皮分离→浸胶→干燥→组坯→板坯冷压→高温固化→脱模→柳树重组复合型材.本文还介绍了柳树重组复合材的生产技术及质量控制技术.     

Apical control of branch movements in white pine: Compression wood action

Summary The movements of branches or control stem girdled white pine (Pinus strobus L.) were analyzed using beam theory. The stresses generated in the compression wood (CW) produced bending moments to counter the added bending moments due to new branch growth. The branches on the treated trees produced additional CW after untreated trees stopped elongation and diameter growth. The intensity of the stresses in this additional CW was greater than in the other CW. Thus, branches on treated trees moved up vertically well beyond their initial orientation due to both more CW and more active CW. The branches on untreated trees all deflected downward as branch weight continued to increase after CW production stopped.     

A review on wood machining: characterization,optimization, and monitoring of the sawing process

ABSTRACT

Sawing is the most common machining process and is present in both primary and secondary wood transformation sectors. The objective of this paper is to review how it is affected by different factors. The current challenges associated with various machining factors, process monitoring, and sensor selection were identified and explained. Consequently, four research challenges and technological gaps were outlined. (1) Contradictory results have been reported due to different cutting processes, wood species, measurement methods, and cutting speed range studied in literature, so special consideration needs to be taken when comparing results with those available in the literature. (2) Laboratory test conditions cannot yet fully represent the extreme cutting conditions in sawmills. More emphasis should be placed on those harsh industrial cutting conditions. (3) Research on wood cutting lacks multi-objective optimization approach, which suggests that sawdust generation should be simultaneously analysed with surface quality and power consumption. (4) Compared with metal cutting, little research has been conducted on wood sawing monitoring using an artificial intelligence approach, which should be prioritized in designing adaptive control systems. Combining intelligent monitoring and multi-objective optimization approaches should pave the way for controlling the sawing process so higher surface quality and cost efficient machining is achieved.     

基于数字图像处理技术实现木材横纹压缩过程中构造学形态特征的研究

根据计算机视觉技术,结合横纹压缩木材构造形态特征,提出了适合于木材横纹压缩过程中构造形态特征的图像处理方法。对图像质量的完善较全面地进行了量化,充分表露出计算机视觉技术在实现木材横纹压缩过程中构造学形态特征动态变化分析中的优越性,实现了木材细胞边缘轮廓的跟踪,形态特征的提取,为木材科学的再发展奠定了理论基础。     

A model of the anisotropic swelling and shrinking process of wood. Part 1. Generalization of Barber's wood fiber model

Summary The anisotropic mechanism of wood swelling and shrinkage was investigated theoretically. The reinforced-matrix hypothesis offered by Barber and Meylan (1964) was reformulated by using a multi-layered wood fiber model, and the formula describing the dynamical behavior of swelling and shrinking wood fiber was derived. For modelling, the moisture content changes were taken into consideration as an explicit parameter. It is expected to predict the anisotropic swelling and shrinking process of wood dynamically and quantitatively, as well as to initiate elucidating the interaction between the moisture and cell wall components on the basis of the present model. Some concrete calculations will be demonstrated in the following report, and the results will be compared with the experimental ones. Received 2 September 1997     

磷-氮-硼复合木材阻燃剂配方优化及处理工艺

探讨了由磷酸、硼酸、双氰胺等为主要组分制备的新型磷-氮-硼阻燃剂的优化配方,以氧指数和烟密度为指标评价了该阻燃剂处理材的阻燃、发烟性能,并进一步优化阻燃处理工艺.结果表明,该阻燃剂主要组分双氰胺、磷酸、硼酸最佳配方摩尔比为0.095∶0.102∶0.162.经阻燃处理后的杨木木材,其氧指数从23.4%提高至60%,烟密度由40.64%降至25%.同时得出的优化处理工艺为浸渍浓度5%,浸渍时间84 h,浸渍温度60℃.     

林果蛀干害虫防治方法

林果蛀干害虫大都营隐蔽生活,危害严重,防治难度较大.该文介绍了7种林果蛀干害虫防治方法,即树干涂药包扎法、树干打针注射法、根部埋药法、樟脑丸法、野生芫花防治蛀干害虫、应用磷化锌毒签防治蛀干害虫、绿色威雷喷雾防治成虫技术,简便易行,技术先进适用,效果好,经济环保,推广前景广阔,有望对解决蛀干害虫防治难题提供助益.     

多规格木板自动码垛机控制系统设计与实现

为了实现对一种错位双链木板循环输送码垛机结构的多传动系统协调控制,以提高木板的码垛效率,满足多规格木板码垛需求,设计了一种多输入多输出的木板码垛柔性控制系统。基于分模块控制系统设计理论,以PLC及扩展接口为核心,多激光传感器和触点开关为反馈信息输入,协调控制不同传动系统的多个电机,以实现木板的输送、规整和码垛。通过样机的试验,所设计的控制系统功能完整、性能稳定,自动化木板码垛比人工码垛效率高、效果好。     

Decision-making for the selection of a best wood extraction method: An analytic network process approach

The importance of environmental and economical aspects in sustainable forest management (SFM), demands a continuing need for the application of efficient methods in this field. In this paper, we applied analytic network process (ANP) with benefits, opportunities, costs, and risks (BOCR) to evaluate four existing wood extraction methods (rubber-tired skidder, tracked skidder, cable logging and animal skidding) and select the best one based on SFM strategies in the Caspian (Hyrcanian) Forest, in northern Iran. The required data were obtained either from the previous studies or through pairwise comparisons conducted by a panel of forest engineering experts. Based on the BOCR subnetworks and their corresponding criteria, four alternatives were synthesized. ANP analysis indicated that the benefits and risks were more important in terms of decision-making, compared to the opportunities and costs. Finally, the alternative of ‘rubber-tired skidder’ was selected as the most suitable method for meeting SFM strategies. The decision framework proposed in this study offers a means for the reorganizing and planning of timber harvesting operations as an integral step toward SFM. By making minor adjustments for local conditions, this decision framework can be adapted for many other regions and countries.