实木地板榫槽铣削力的试验分析

【目的】以实验为基础,研究实木地板榫槽铣削加工中切削参数对切削力的影响,为不同切削工艺下加工参数的优化以及设置提供参考依据,达到提高加工质量、延长刀具寿命并用以指导生产的目的。【方法】以山毛榉材地板为试验材料,运用木材切削机理对切削速度、进给速度及切削宽度3个参数进行单因素试验,并采集切削过程中随着切削参数变化产生的切削力值,揭示在顺铣和逆铣方式下不同切削参数对实木地板榫槽铣削力的影响规律。【结果】在不同铣削方式下,随着切削速度的增大,XYZ方向的切削力总体呈降低趋势;随着进给速度和切削宽度的增大呈现升高的趋势,顺铣加工时XYZ 3个方向的铣削力变化相比逆铣加工的波动趋势小,稳定性要好。通过对铣削力回归模型进行方差分析,可知R2(Fdown)=0.9490,R2(Fup)=0.8516,均接近1,回归效果显著,验证了铣削力模型的合理性。【结论】通过对比相同切削参数在不同工艺条件下产生的切削力变化,可知顺铣加工稳定性高于逆铣加工。     

国内外木结构数控加工中心产品技术现状与发展

随着木结构行业的快速发展,木构件数控加工成为行业发展的必然趋势。但国内对专业木结构数控加工中心研发很少,主要依赖价格和操作技术门槛高的欧美进口加工中心,导致国内木结构建筑成本高,因此亟待开展国产木结构数控加工中心研发,促进木结构产业快速发展。文中主要围绕木结构数控加工中心的产品技术,从国内外加工中心产品现状、主要技术进展和未来展望3个方面进行综述,介绍德国、意大利等发达国家水平较高的数控加工中心的产品及功能参数以及国内数控加工中心产品及技术现状,分析目前木结构数控加工中心的主要技术进展,总结国内木结构数控加工中心存在的问题,并在此基础上展望国内加工中心通用化、高性价比、定制化和智能化的发展方向,以期促进国产木结构建筑构件数控加工中心的研发,为木结构企业提供高性价比的数控加工中心产品和稳定的售后服务。     

人工林难胶合木材的研究现状

从木材密度、抽提物、加工性能等方面讨论人工林难胶合木材胶合困难的主要原因,阐述改善胶合性能的主要措施.胶合面加工质量的改善、抽提物处理和润湿性改进等,是目前改善人工林难胶合木材胶合性能的主要方法,但是效果不显著,还有待进一步研究.     

杨木和辐射松树脂增强改性材机械加工性能研究

为考察杨木和辐射松树脂浸渍材的机械加工性能,参照LY/T 2054—2012《锯材机械加工性能评价方法》,分别对杨木和辐射松的素材与树脂浸渍材及其经过真空热处理的树脂浸渍材的刨削、铣削、钻削、开榫和车削5种机械加工性能进行测试评价。结果表明:1)本试验范围内,在综合评分满分40分情况下,杨木素材、树脂浸渍材和真空热处理树脂浸渍材的总评分分别为20分、30分和25分;辐射松素材、树脂浸渍材和真空热处理树脂浸渍材的总评分分别为24分、33分和29分;树脂浸渍材机械加工综合性能最佳,热处理树脂浸渍材次之;2)杨木和辐射松的树脂浸渍材及其真空热处理树脂浸渍材的刨削、铣削性能均为优秀,车削性能均为良好;杨木和辐射松的树脂浸渍材及辐射松真空热处理树脂材开榫性能良好;钻削性能仅辐射松树脂浸渍材达到优秀;3)辐射松素材与改性处理材的机械加工性能均优于杨木,综合比较,辐射松树脂浸渍材具有较佳的机械加工性能。     

Analysis of sanding parameters on surface properties and coating performance of red oak wood

Sanding is the most common machining process used to prepare wood surfaces prior to coating. Hence, to improve surface quality and coating performance during this process, an optimal set of machining parameters should be established according to wood species and its final use. The effects of grit size and feed speed on surface properties and coating performance of red oak wood were studied. Surface quality was assessed by surface roughness, scanning electron micrographs, and wetting analyses. Coating performance was evaluated using pull-off adhesion tests on coated surfaces before and after an accelerated weathering. The results showed that smoother surfaces are obtained as the grit size number of the abrasive increased. On the other hand, minor differences were observed on cell damages and surface roughness as feed speed changed. Also, there was little difference among treatments concerning wetting behavior and surface energy. Pull-off strength was more affected by changes in grit size than feed speed. A P100-grit size program with a feed speed of 7 m/min resulted in a suitable roughness which provided good adhesion and high pull-off strength after aging test.     

Prediction of the surface roughness of wood for machining

The surface quality of solid wood is very important for its effective response in manufacturing processes. The effects of feed rate, cutting depth and rake angle on surface roughness and power consumption were investigated and modeled. Neuro-fuzzy methodology was applied and shown that it could be useful, reliable and an effective tool for modeling the surface roughness of wood. Thus, the results of the present research can be successfully applied in the wood industry to reduce time, energy and high experimental costs.     

Effects of grain angle on the amplitudes of acoustic emission and surface roughness in wood machining

The orientation of wood fibers and the resulting surface roughness of radiata pine are studied during a peripheral milling with acoustic emission control. Studies were undertaken in machining process for radiata pine, where a surface quality problem appears when cutting is not well controlled. It is known that acoustic emission signals are a good monitoring element of the surface roughness with different cutting conditions. Previous studies have shown that changing cutting conditions affects acoustic emission signals; these variations are related to surface roughness and chip formation. The purpose of this study is to evaluate and quantify the surface quality and the consumption of cutting energy in radiata pine with differing grain angles, and to determine the relationships of grain angle with acoustic emission signals in order to better optimize cutting conditions.     

Analysis of birch wood lignin by oxidative degradation

Summary The lignin in birch wood has been subjected to analysis by oxidative degradation after milling of wood samples in a Wiley mill and in a rotatory ball mill. For comparison milled wood lignin from birch has also been analysed. It was found that the type of milling affects both the total yield of degradation acids and their relative frequency of occurrence. These findings are interpreted as being due to a cleavage of aryl ether linkages during the milling procedure. The oxidative degradation analysis gave rise to a total of 30 different acids which were tentatively identified on the basis of their mass spectral fragmentation patterns. Among the acids some were found having either a phenoxyacetic acid or a phenoxypropionic acid structure. The possible origin of these is discussed. A grant to one of us (R.A.N.) from Jacob Wallenbergs Forskningsstiftelse is gratefully acknowledged. Thanks are due to Kristina Gustafsson for skilful experimental assistance     

Relationship between ball milling and the susceptibility of wood to digestion by cellulase

Summary Aspen wood was ball milled for times as long as 10 days. The change in wood morphology was examined in the ultraviolet microscope. The accessibility of the milled wood to cellulase was also determined. Soon after the commencement of the milling, part of the wood took on a characteristic appearance in which the cell wall material was completely broken down. The proportion of this disordered wall material (DWM) increased with increased time of milling. The accessibility to cellulase increased with the proportion of DWM produced by the milling.The authors wish to acknowledge the interest and valuable advice of Dr. B. A. Pethica throughout the conduct of this research     

木材的机械加工性能研究现状与进展

本文概述了木材机械加工性能研究的现状，介绍了木材加工性能测试和评价的标准。分析了进行木材机械加工性能研究的重要性和迫切性，并对木材机械加工性能的研究方向和发展趋势提出了建议。     

支持向量机参数优化方法在木质粉尘火花探测中的应用

为提高木质粉尘火花检测的准确性,利用基于支持向量机(SVM)的物质分类方法检测木质粉尘火花。选取马尾松和杨木粉尘为研究对象,将两种粉尘分组点燃试验,获取火花和灰分的高光谱图像,提取感兴趣区域(region of interest,ROI)内的发光度数据进行预处理。利用感兴趣区域内的数据建立SVM分类模型,分别利用网格搜索法(GS)、遗传算法(GA)以及粒子群算法(PSO)对两类树种的SVM分类模型进行参数优化,并将三种参数优选方法的分类预测准确率进行对比。结果表明,三种优化方法均能够很好地检测两种树种的木粉火花,其中网格搜索法检测准确率明显高于其余两种,更适于木质粉尘火花探测,这为人造板生产过程中能够高效检测木质粉尘火花提供了一定的理论依据。     

线性规划、模拟退火和遗传算法在杉木人工林可持续经营中的应用和比较

以杉木人工林为例 ,介绍了线性规划、模拟退火和遗传算法在编制森林经营方案过程中的应用和比较 ,同时介绍了一种通用的可以处理绝大多数的森林经营模型。采用Hui(1997)的生长和间伐模型来模拟林分的生长、间伐和发展过程。线性规划、模拟退火和遗传算法三者适用于不同的场合。当约束条件都比较宽松时 ,线性规划也有可能得出整数解 ,但不一定就能够避免林分分割经营 (整数解 )。要获得整数解 ,尤其是在林分数目很大的时候 ,可以采用模拟退火和遗传算法。如果允许林分分割 ,线性规划的结果一般可以获得最好的目标方程值。     

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.     

表面涂层木工刀具的研究进展

介绍几种表面涂层木工刀具的加工方法和使用状况,分析表面涂层刀具的切削特点和磨损形态,概述了国内外研究进展.研究成果表明,涂层处理可以延长刀具使用寿命,减少刃磨和换刀时间,提高生产效率和表面加工质量.     

Enzymic isolation of lignin from wood and pulps

After enzymic hydrolysis of polysaccharides in milled wood or pulp the unhydrolysed lignin residue becomes soluble in certain polar solvents. Extensive disintegration of the wood is necessary to obtain a sufficient accessibility toward the enzyme. For milling a porcelain rotary ball mill is recommended. A relationship has been found between the milling energy, which is proportional to the size of the mill, the milling time, and the yield of ball-milled wood lignin (BMWL). Enzymatically isolated lignin (EIL) requires a critical milling time which is shorter than that for obtaining maximum yields of BMWL. A procedure for isolation of the total lignin content from wood and pulps in the form of three fractions has been developed, giving a water soluble, low molecular carbohydrate-lignin complex by water extraction of ball-milled wood, a BMWL-carbohydrate complex by subsequent extraction with dioxane, and a EIL-carbohydrate complex by dioxane extraction of the residue after enzymic hydrolysis.     

基于应力波的活立木力学特性无损检测研究进展

活立木力学特性无损检测是科学评价森林质量的基础,为合理制定采伐作业时间、原木分级和木材高效利用提供有效依据.介绍应力波无损检测的基本原理以及基于应力波的活立木力学特性无损检测的研究进展,分析影响应力波在活立木中传播的因素,在此基础上阐述木材力学特性变化的原理以及基于应力波技术的木材力学特性季节动态变化检测的现状和意义,提出应力波检测活立木性质存在的问题,针对其存在的问题提出几点建议.     

国外对杨树湿心材的研究

杨树是我国主要速生造林树种之一。杨树的利用对我国林业和林产工业的发展有重要影响。湿心材是树木生长中的一种反常现象,在杨树中表现甚为突出,是杨树加工利用中的一大难题。国外对湿心材的研究于上世纪初即已开始,已取得许多研究成果。本文扼要介绍国外研究的进展和一些重要观点,涉及湿心材的形成,湿心材中的细菌、气体和水分,湿心材的酸度、材色、力学强度、渗透性和湿心材对干燥、人造板生产和刨削等工艺过程的影响。     

木浆纤维素粉的研制及其在合成革生产中的应用

本文对合成革用纤维素粉的制备和应用,进行了研究。以木材溶解浆为原料,采用“疏解备料—缓和水解—抽滤洗涤—低温干燥—两段造粉”工艺路线,进行了生产性试验。纤维素粉产品在合成革厂进行了批量应用试验。 试验结果表明 采用此工艺用木材溶解浆制成的纤维素粉能够作为平滑涂布液的增粘剂而用于合成革生产。这一工艺具有性能稳定、产品质量好和较高经济效益等优点。是一条可行的生产工艺。     

Studies on milled wood lignin from spruce Part II. Electron microscopic observations on the milled wood

Summary Wood samples that had been ball-milled and extracted with dioxane under various conditions were observed in the scanning electron microscope. Ball milling causes not only a reduction in size of the cells and cell walls but also an internal disruption of the particles. The intensity of milling has a larger influence on the particle size than a prolongation of the milling time. A direct relation was established between particle size and the previously determined yield of purified milled wood lignin.Submitted by Erwin-Riesch-Stiftung zur Förderung der wissenschaftlichen Forschung.     

Recrystallization behavior of cellulose and lignocellulose from Pinus massoniana

Summary In an X-ray diffraction investigation, the recrystallization behavior of ball-milled Chinese southern pine wood was found to differ from that of cellulose. The crystallinity of lignocellulose milled for a very long time and recrystallized by wetting in water did not decrease with increasing milling time as was the case with milled cellulose. In addition, it appeared that the presence of lignin tended to restrict the amorphous cellulose produced by milling from recrystallizing into Cellulose II, whereas it had no influence on the recrystallization into Cellulose I. These results were discussed in the context of the mechanism of the conversion of Cellulose I to Cellulose II.