单板类人造板的密度分布研究

研究了几种单板类人造板的平面内密度分布(HDV)和厚度(剖面)上密度分布(VDP),分析了密度分布的变化规律。试验结果表明:与刨花板和纤维板相似,单板类人造板在平面和厚度上也存在着密度差异,但是其特点有所不同。     

单板覆面刨花/发泡聚苯乙烯木质复合板的开发

为拓展低密度人造板的应用领域,以杨木刨花和可发泡聚苯乙烯为原料制备复合材料(芯材),并在其表面贴覆杨木单板制成木质复合板,以提高板材的力学性能。结果表明,当复合板的密度在0.42~0.48 g/cm3时,板材的内结合强度和静曲强度达到国家标准A类刨花板二等品的要求,导热率低于0.050 W/(m.K),可用于家具、室内装饰的非受力部件及墙体保温材料。     

第2讲 板式家具部件的主要切削刀具

1 概述 板式家具是以各种贴面的人造板作为板式部件,借助五金联接件、圆棒榫等结合方式组装而成的家具.板式部件是贴面人造板基材和封边材料组成的复合结构材料.常用的基材有中密度纤维板、刨花板、多层胶合板、细木工拼板和单板层积材等人造板;贴面材料主要有三大类:木质、纸质和塑料.木质贴面材料包括灭然薄木、人造薄术和单板等;纸质贴面材料有印刷装饰纸、合成树脂浸渍纸和装饰板;塑料贴面材料有聚氯乙烯(PVC)薄膜和聚丙烯薄膜.     

秸秆刨花板性能分析

对普通木质刨花板、麦秸刨花板及稻草刨花板进行了密度、含水率、吸水厚度膨胀率、静曲强度和弹性模量、内结合强度、表面结合强度及握钉力的测试,结果表明,麦秸刨花板在强度方面不及木质刨花板,稻草刨花板在抗弯性能上也无法满足要求,两种秸秆板的握钉力都较差。产生上述差距的关键原因是板坯的密度,另外,与原料形态、加工工艺、机械设备等也有关系。     

胶合板层间水分迁移规律的研究

胶合板是一种重要的木质工程材料,其纵横交错的组坯方式有效地降低了木质材料的各向异性,因此,胶合板常用于室外环境以代替实木作为结构材使用。由于木材固有的易吸湿性,吸水可改变胶合板的物理力学性能。为探索胶合板层间水分迁移规律,使用X射线断层扫描仪检测吸水前后2种杨木胶合板和杨木试件内水分迁移行为,分析了影响胶合板内水分迁移行为的原因,剖析了吸水过程中胶层和单板结构变化对胶合板吸水行为的影响。研究结果表明,水分在胶合板层间迁移可分为吸湿后木材单板发生润胀、单板间胶层不再连续和完整、水分在板层间孔隙聚集和水分穿过胶层并进入下一板层4个步骤。水分更易在木质单板内高密度区域聚集以及沿结构存在缺陷区域迁移。本研究动态可视化了吸水过程中胶合板内水分分布及胶层形态变化,揭示了胶合板内水分穿过胶层的发生机制,这一研究成果可为优化人造板生产工艺和指导人造板的合理使用提供理论基础。     

锯齿磨损变钝程度对木质材料切削力影响的研究

采用锯齿磨损变钝程度不同的硬质合金切削刀具对三种木材(杉木、樟子松、水曲柳)和两种人造板(中密度纤维板、刨花板)进行闭式切削实验,研究锯齿磨损变钝程度对木质材料切削力的影响规律。实验结果表明,随着刀具磨损变钝程度的增加,主切削力和法向力都呈增大趋势,且法向力的增幅更明显。负间隙C对中纤板主切削力、法向力以及刨花板法向力的影响曲线类似,均为先缓慢上升,再急剧增加,然后又趋于平缓;刨花板主切削力随负间隙C的增加而不断增加。     

木质人造板断面密度分布的检测--介绍一种在线实时检测新技术

十几年来,由于木质人造板的断面密度分布检测能够真实地反映加工工艺及最终产品的物理力学特性,经常性地检测产品的断面密度分布已成为质量控制中不可或缺的手段,特别是MDF生产线和大多数的现代化刨花板生产线。 “人造板的断面密度分布检测技术”大体上走过3个阶段:人造板样品分层称重检测;人造板样品在实验室采用γ射线扫描检测;人造板在生产线连续由X射     

密度

目前,低密度纤维板是市场的宠儿,但是密度又影响了机械强度.正因为如此,Mark Irle博士指出,密度板生产商在生产过程中必须严格控制生产线. 木质人造板的机械性能通常随着他们的密度增加而增加.这一正比关系在刨花板和纤维板上的表现尤其明显.对于一个特定的人造板类型而言,相同的原材料在特定的生产线上生产的产品,机械性能和密度的关系基本上可以保持线性关系.     

论刨花板平面密度变异

刨花板平面密度的变异性是衡量板坯成形个常指标。本文论述了影响刨花板平面密度变异的工艺因子及平面密度变异对刨花板性能的影响。     

枝桠材制备木质刨花板成板工艺及性能研究

采用柳树枝桠材制得的片状刨花制备木质刨花板;通过正交试验设计,研究施胶量、预设密度以及石蜡添加量对板材物理力学性能的影响。结果表明,预设密度对静曲强度和静曲弹性模量均有显著的正相关线性影响,对内结合强度有显著影响;施胶量对静曲弹性模量和内结合强度有一定的正相关影响;所有试验因素对2 h吸水厚度膨胀率均有一定影响。从板材性能和成本角度考虑,确定柳树枝桠材制备木质刨花板的最佳工艺为:施胶量7%,预设密度0.7 g/cm~3,石蜡添加量4%。     

Effects of Horizontal Density Distribution on Internal Bond Strength of Flakeboard

Along with the worldwide decrease of round woodwith high quality and large diameter day by day, theoutput of lumber and plywood used in constructionis declining year by year. But the market demand forcomposites keeps rising. Non-veneer woodcomposites (Oriented Strand Board, Flakeboard,Medium Density Fiberboard) will be the mainstreamof composites in the future. At present, OrientedStrand Board and structural flakeboard have to a largedegree replaced structural plywood in buildingconstructi…     

Reducing resin content and board density without adversely affecting the mechanical properties of particleboard through controlling particle size

Density and resin content are two factors that have a signifi- cant effect on the production cost of wood composite. However, particle size affects resin content and density, which suggests that the interaction of these three factors can be manipulated to reduce the board density and resin content of particleboard without adversely influencing its mechani- cal properties. Some mathematical functional forms based on resin con- tent, board density and slenderness ratio were regressed and an appropri- ate form was chosen. According to analysis of the results using SHA- ZAM 9 software, the exponential function best fit the experimental data. Finally, "indifference curves" of mechanical properties were illustrated and analyzed. The results indicated that negative effects of density or resin content reduction on mechanical properties could be compensated for by controlling particles’ slenderness ratio. Interestingly, increases in slenderness ratio compensated for the negative effects of decreases in resin content or board density on module of rupture (MOR) and module of elasticity (MOE). Moreover, this "compensation ratio" intensified as resin content or density decreased and/or as the MOR or MOE increased. On the other hand, reduction in slenderness ratio indicated a comple- mentary effect on reducing internal bond (IB) strength, a result of de- creases in resin content or density. Moreover, this "complementary ratio" was intensified as resin content or density decreased and/or as IB strength increased.     

Effect of element type on the internal bond quality of wood-based panels determined by three methods

Three mechanical tests with different loading modes were conducted to evaluate the effect of element type on the internal bond quality of wood-based panels. In addition to the internal bond test, which is commonly used for mat-formed panels, interlaminar and edgewise shear tests were used to test oriented strandboard (OSB), particleboard, medium-density fiberboard (MDF) of two thicknesses, and plywood. The following results were obtained. Epoxy resin proved to be suitable for determining the interlaminar shear modulus instead of hot-melt glue. There was a linear relation between panel density and interlaminar shear modulus and a linear correlation between the interlaminar shear strength and internal bond (IB) strength for the mat-formed panels tested. OSB had the highest edgewise shear modulus, and MDFs had the highest edgewise shear strength in this study. The modulus/strength ratio also depended on both panel type and loading mode. The relation between the shear moduli determined from the edgewise and interlaminar tests indicated the characteristics of the shear properties of panels made of different elements.Part of this paper was presented at the Fourth International Wood Science Symposium, Serpong, Indonesia, September 2002     

大豆蛋白胶稻草碎料板制备关键工艺参数研究

采用自制大豆蛋白胶,通过热压法对稻草碎料板的制备工艺参数进行了系列试验的结果表明：稻草碎料板的静曲强度（MOR）在施胶量为71%时（相当于粗蛋白添加量为12%）最强,接近GB/T 21723-2008的要求;稻草碎料板的内结合强度（IB）随着施胶量的增大而增强,在施胶量为82%时（相当于粗蛋白添加量为18%）,内结合强度接近GB/T 21723-2008的要求;稻草碎料粒径对稻草板的静曲强度和内结合强度影响不显著,稻草碎料板的静曲强度和内结合强度随板材表观密度增大而显著增强。     

Digital X-ray analysis of density distribution characteristics of wood-based panels

Twelve commercial nominal 4 × 8 ft.² (1,200 × 2,400 mm²) wood-based panels, Medium Density Fiberboard, Particleboard, Oriented Strand Board and Plywood, were scanned for horizontal density distribution using a high resolution and accuracy digital X-ray system. Density distribution at a size of grid cell varying from 0.5 × 0.5 to 12 × 12 in.² (12.7 × 12.7 to 304.8 × 304.8 mm²) was analyzed based on the X-ray scanned images of the panels. Detailed density distribution characteristics of the four types of wood-based panels are presented in this research. Comparisons of density variation are carried out between different panel types and between different spatial resolutions (i.e. sizes of grid cells). Results of analysis and comparison in density distribution are presented in different forms with industrial as well as academic implications.     

Behavior of acoustic emission generation during tensile tests perpendicular to the plane of particleboard II: effects of particle sizes and moisture content of boards

Particleboard specimens with various particle sizes were conditioned into two ranges: low and high moisture content. One set was investigated for internal bond (IB) strength and acoustic emission (AE) events during tensile tests perpendicular to the plane and the other for ultrasonic wave transmission characteristics in the thickness direction. The particleboard structural mechanics were changed as a result of the moisture effect. Specimens conditioning to higher moisture content had lower IB strength and lower cumulative acoustic emission event counts (T _AE). The decrease in IB strength indicated that the irreversible thickness swelling was seen when recovery forces of the particles exceed the restraining action of the adhesive. This was attributed to stress release, which resulted in internal failure of the board. The change in the internal structure caused an increased stress level at the initiation of AE generation. No events were recorded before this stress level, obeying theKaiser effect. The decrease inT _AE was not only related to the decrease in IB strength but was also affected by the transformation (attenuation) of the AE signals during IB tests according to the mesh size used.Part of this paper was presented at the 45th and 50th Annual Meetings of the Japan Wood Research Society, Tokyo and Kyoto, 1995 and 2000, respectively     

Formation of the density profile and its effects on the properties of particleboard

Summary Two types of particleboards bonded with an isocyanate resin, one with uniform vertical density profile (homo-profile), and the other with conventional U-shaped profile, were fabricated to various density levels using lauan (Shorea spp.) particles. The fundamental relationships between the density profile and the board properties were determined, and the results are summarized as follows: 1. In homo-profile boards, the moduli of rupture (MOR) and elasticity (MOE), internal bond (IB) strength, and screw withdrawal resistance (SWR), are highly correlated to the board mean density. 2. The bottom limit of the board density is estimated to be ca. 0.25 g/cm³, based on the correlation regressions between mechanical properties and mean density. 3. At equal mean density level, the MOR and MOE of the conventional particleboards are higher than the homo-profile boards, due to the higher density near the faces. However, the reverse is true for IB, owing to the presence of the low density core in the former. 4. The net impact of peak density on MOR and MOE is greater at higher mean density level while raising the core density results in more pronounced improvement in IB at lower density. 5. In addition to the compaction ratio, the dimensional stability of the board is also affected by the peak area and mat moisture content. Received 9 January 1997     

Improve regression-based models for prediction of internal-bond strength of particleboard using Buckingham’s pi-theorem

Internal bond (IB) strength is one of the most important me-chanical properties that indicate particleboard quality. The aim of this study was to find a simple regression model that considers the most ...     

Cement-bonded particleboard with a mixture of wheat straw and poplar wood

We investigated the hydration behavior and some physical/mechanical properties of cement-bonded particleboard (CBPB) containing particles of wheat straw and poplar wood at various usage ratios and bonded with Portland cement mixed with different levels of inorganic additives. We determined the setting time and compression strength of cement pastes containing different additives and particles, and studied the effects of these additives and particles on thickness swelling, internal bond strength and modulus of rupture of CBPB by using RSM (Response Surface Methodology). The mathematical model equations (second-order response functions) were derived to optimize properties of CBPB by computer simulation programming. Predicted values were in agreement with experimental values (R2 values of 0.93, 0.96 and 0.96 for TS, IB and MOR, respectively). RSM can be efficiently applied to model panel properties. The variables can affect the properties of panels. The cement composites with bending strength > 12.5 MPa and internal bond strength > 0.28 MPa can be made by using wheat straw as a reinforcing material. Straw particle usage up to 11.5% in the mixture satisfies the minimum requirements of International Standard, EN 312 (2003) for IB and MOR. The dose of 4.95% calcium chloride, by weight of cement, can improve mechanical properties of the panels at the minimum requirement of EN 312. By increasing straw content from 0 to 30%, TS was reduced by increasing straw particle usage up to 1.5% and with 5.54% calcium chloride in the mixture, TS satisfied the EN 312 standard.     

广宁县竹香骨下脚料制备竹碎料刨花板及其复合改性研究

采用竹香骨下脚料为原料,以脲醛树脂和三聚氰胺改性脲醛树脂胶粘剂制备竹碎料刨花板,并与木纤维复合改性,检测并分析了内结合强度、静曲强度、弹性模量和吸水性。结果表明,在热压温度为160℃时,竹碎料板和竹木复合碎料板的物理力学性能均满足国标规定在干燥状态下使用的普通用板要求。当木纤维与竹碎料复合后,复合板材的静曲强度和弹性模量有一定程度提高,但内结合强度降低。