对提高非结构集成材出材率的几点建议

集成材是一种沿板材或方材平行纤维方向,用胶粘剂沿其长度、宽度或厚度方向胶合而成的材料。集成材的原料是由制材加工剩余物及短小料制成的,其既保持了木材的天然纹理,又提高了木材的各项物理性能,做到了小材大用、劣材优用,完全可以替代实体木材。但其与实体木材相比,集成材的出材率较低,产品的原料成本高。现就此问题,根据我单位多年加工集成材的经验,总结出以下几点建议,供各集成材生产厂家做参考。     

水曲柳含水率对集成材胶接性能的影响

在现代木材加工工业生产中，对胶粘剂的依赖性不断增强，胶接质量已越来越成为影响木制品质量的一个重要因素。影响木材胶接性能的因素很多，有木材密度、树种等木材固有的因素，也有被胶接木材的含水率、表面粗糙度等加工过程中所产生的因素。本文从木材的干燥质量，主要是木材的含水率入手，对于不同树种满足集成材胶接对含水率的要求做了初步探索，并给出了相应的干燥工艺，这对于实际生产有着一定的指导意义。     

提高集成材出材率的措施

集成材生产是木材综合利用的有效途径,是木材加工业的重要组成部分,我国集成材生产中普遍存在出材率低、成本高、影响经济效益等问题,结合我国集成材生产实践,提出几点提高集成材出材率的措施。     

集成材产品质量的控制

集成材产品应用广泛，相应对集成材产品的质量要求较高。本文从木材含水率、基材加工质量及胶拼加工等方面对集成材产品的质量加以控制。     

弯曲竹材集成材的初探

利用竹材在湿热条件下优良的软化弯曲性能和定型特性，试验探索了适宜竹材的弯曲胶合工艺。结果表明，弯曲竹材集成材工艺易于实现，可增加竹制品的花色品种和提高产品附加值，扩展竹材资源利用途径。     

集成材实木门的结构与加工工艺

本文简述了以集成材为基材,以珍贵材种为饰面材料,辅以人造板材料,生产集成材实木门的结构与加工工艺.     

非结构集成材加工技术及质量控制

介绍了非结构集成材的分类,阐述了非结构集成材工艺流程、刨削加工、加工余量、操作技术及安装刀具的规则。确定了非结构集成材加工质量要求。     

落叶松非结构集成材加工工艺的研究

以短周期工业材落叶松为原料生产非结构集成材，解决了劣材优用问题，提高了木材利用率，为家具制造和室内装修提供了理想的优质材料。     

利用枝丫材生产组合板材

利用枝丫材生产组合板材郑忠福（永安市纤维板厂福建永安３６６０００）本厂采用枝丫材及小径材制成组合板材，提高了枝丫材的利用价值，降低了木制品成本，取得了明显的经济效益。１组合板材的结构和特点组合板材是按照胶合板组坯形式经组坯热压而成的一种人造板材。它除...     

家具用落叶松集成材的加工工艺

通过对家具用集成材加工工艺的研究。确定了最佳工艺参数。对样品的测试结果表明，其含水率和浸渍剥离2项主要指标均符合相关标准的要求。因其使用了环保型无毒胶粘剂。使集成材在家具制造领城的应用具有广泛的前景。     

Tensile strength of thermally modified laminated strand lumber and laminated veneer lumber

Laminated strand lumber (LSL) and laminated veneer lumber (LVL) were thermally modified as a post-treatment at 140°C, 150°C, 160°C, 170°C, and 180°C. The tension modulus of elasticity (MOE) of LSL was not significantly impacted by the treatments, with the 180°C treatment group exhibiting the highest tension MOE (11.8?GPa). The LVL also experienced minimal impacts, with the 150°C treatment group having the highest tension MOE (19.4?GPa) and the 160°C treatment group exhibiting the lowest (17.1?GPa). The maximum tensile strength (MTS) of the LSL and LVL significantly decreased with increasing temperatures, with the control and 180°C treatment groups experiencing the highest and lowest MTS, respectively. The lowest MTS for LSL was 10.8?MPa (180°C treatment), which was 70% lower than the controls. The lowest MTS of the LVL was 24.4?MPa (also at the 180°C treatment), which was a 49% decrease compared to the controls. These results suggest that thermal-modification post-treatments minimally impact tension MOE, but can significantly reduce MTS at higher treatment temperatures. Combined with previous work improving the moisture properties and equilibrium moisture content of thermally modified LSL and LVL, it may be possible to optimize the treatment technique(s) to yield products with desirable properties.     

薄型单板层积材结构改进的研究

薄型单板层积材(LVL)可替代锯材,应用于木质门窗构件等轻载结构领域.由于单板全部顺纹组坯,导致产品存在横向翘曲变形的技术问题.为此,尝试采用"部分单板横纹组坯"和"纤维板与单板复合"两种方法进行改进,制造了15 mm厚LVL,包含1～2层单板横纹组坯或1～2层3 mm纤维板.测试结果表明:单板横纹组坯.显著降低了LVL的抗弯性能,但LVL的弹性模量仍能达到单板层积材国家标准中70E级别的要求,而静曲强度甚至超过180E级别优等品的限值;与此同时,改进结构的LVL吸水翘曲变形显著降低.横纹单板越靠近LvL表层,板子抗弯性能降低越显著,而翘曲变形改善越明显.采用纤维板与单板复合制造LVL,纤维板的内结合强度衰减明显,易受破坏.     

单板层积材的研究现状

论述了国内外在单板层积材工艺及机理方面研究的主要进展，其中工艺研究包括加压工艺、材种及单板等级等，而机理研究则主要集中在力学性能和耐久性能的研究上。在此基础上对研究竹材增强单板层积材的可行性和必要性进行了探讨，并简要介绍了竹材增强单板层积材研究的进展情况。     

桉木单板层积材生产工艺的优化

采用响应面法(RSM)和中心组合旋转设计(CCRD),研究了桉树单板层积材(LVL)的生产工艺条件,并对优化工艺所得的预测值进行了实验验证。方差分析结果表明:面粉添加量对桉木LVL的静曲强度(MOR)和弹性模量(MOE)有着显著影响,而热压温度和热压时间的影响不显著。通过回归分析,建立了相应的回归模型。回归模型的预测值与实验值的拟合良好,说明回归方程能用来预测和优化桉木LVL的力学强度性能。最佳工艺条件为:热压温度130℃,热压时间1.5 min/mm,面粉添加量5%(质量分数)。在此工艺条件下压制的桉木LVL垂直加载条件下的静曲强度(MOR⊥)和弹性模量(MOE⊥)分别为89 MPa和16 722 MPa,平行加载条件下的静曲强度(MOR∥)和弹性模量(MOE∥)分别为88 MPa和15 067 MPa,MOR和MOE分别达到了结构用单板层积材国家标准的优等品和140E级别。     

Development of constitutive model for laminated veneer lumber using digital image correlation technique

This paper describes the development of a three-dimensional constitutive model for laminated veneer lumber (LVL) needed for new developments using this material. The LVL was manufactured in New Zealand from Radiata Pine. Experimental testing has been performed according to European timber testing standards. Block compression testing has resulted in modulus of elasticity values in the three material directions. Digital image correlation (DIC) technique has been used to determine the six Poisson’s ratios. Shear testing, whereby timber specimens were glued between two steel plates, has given stiffness values using DIC measurements. Experimental testing results have been compared with values found in literature. Results from this experimental testing programme have made it possible to create a three-dimensional elastic material model of LVL for the use in finite element analysis programmes. Although the material properties do not result in a symmetrical constitutive matrix, only minor adjustments are needed to gain the benefits of a symmetrical matrix.     

杉木小径材制造单板层积材技术的研究开发

利用人工林杉木小径材制造单板层积材对于高效利用小径材资源和缓解结构用木材供需矛盾具有十分重要的意义。介绍了《杉木小径材制造单板层积材及应用研究》课题组利用杉木小径材制作单板层积材的研究过程、工艺开发、设备制造和产品应用方面所作的工作和研究成果。     

Effect of size on the bending strength of laminated veneer lumber

Summary The effect of size on bending strength has been experimentally determined for laminated veneer lumber. Width was found to have no effect on bending strength. The effect of depth times length on bending strength obtained by the slope method was about 0.075, which is in good agreement with the results obtained by the shape parameter method. The effect of length is somewhat more severe than the effect of depth. Size was found to have no effect on modulus of elasticity or modulus of rigidity.In addition, the relationships between bending strength, modulus of elasticity and density of laminated veneer lumber were experimentally modelled.The author is pleased to acknowledge Research and Development Manager Matti Kairi, who represents the Kerto laminated veneer lumber manufacturer of Finnforest Oy, for fruitful co-operation over several years. The patience of senior research scientist Markku Kortesmaa, who calculated and several times explained the details of Appendix A for the author, is also acknowledged     

Strength properties of laminated veneer lumber in compression perpendicular to its grain

Tests of compression perpendicular to the grain were carried out on laminated veneer lumber (LVL) and timber. The species tested were sugi, radiata pine, karamatsu, akamatsu, and dahurian larch; two sets of sugi specimens were tested, with the sugi LVL products being manufactured in different plants. The strength properties of the materials for different loading directions were compared for LVL and timber. At 5% compressive strain in the same materials, the average stress in the tangential direction of timber was larger than that in the radial direction for all species except for radiata pine, and the average stress in the edge-wise direction of LVL was larger than that in the flat-wise direction for all species except for radiata pine. When the stress at 5% strain was compared in the same direction, the average stress of LVL in the edge-wise direction was larger than that in timber in the tangential direction for all species, but there were no great differences between the average stress of LVL in the fl at-wise direction and that of timber in the radial direction for all species except for radiation pine. There was a close relationship between density and stress at 5% strain in LVL, especially in the edge-wise direction. For all results, radiata pine did not follow the trend of the other species; The large annual ring width of radiata pine was considered to have affected the results.     

增强型杨木单板层积材力学性能分析

采用玻璃纤维布与碳纤维布复合材料及分步热压法增强杨木单板层积材,研究了玻璃纤维布与碳纤维布复合材料的铺设位置及分步热压法对杨木单板层积材力学性能的影响.结果表明:两种增强方式对杨木单板层积材静曲强度(MOR)和弹性模量(MOE)的增强效果均较明显;采用对称铺设相同的增强材料时,铺设位置靠近杨木单板层积材表层时对MOR和MOE等力学性能的增强效果较铺设在靠近芯层时的增强效果明显;采用分步热压法可以明显改善单板层积材水平剪切强度.     

Fracture behaviour of laminated veneer lumber under Mode I and III loading

Mode I and Mode III loading experiments were performed on side grooved CT specimens of two types of Laminated Veneer Lumber (LVL). Steady state crack propagation was maintained in order to detect complete load displacement diagrams. Fracture behaviour and influence of fiber orientation were studied and all important fracture mechanical values (stiffness/compliance, microstructural damage, crack initiation energy, specific fracture energy etc) were determined. Much higher crack initiation energies and specific fracture energies resulted in mode III loading than in mode I loading for both material types. Under external mode III loading, crack initiation occurs in mode III and crack propagation however takes place under mode I owing to crack surface interference. The influence of fiber orientation on fracture mechanical properties of LVL was discussed. Received 15 September 1999