小径原木干燥工艺初探

本文是在桦木（Ｂｅｔｕｌａｐｌａｔｙｐｈｙｌｌａ）、刺槐（Ｒｏｂｉｎｉａｐｓｅｕｄｏａｃａｃｉａ）与水曲柳（Ｆｒａｘｉ－ｎｕｓｍａｎｄｓｈｕｒｉｃａ）等小径原木干燥可行性分析与干燥特性研究等工作的基础上，总结出了小径原木的干燥工艺过程。生产实践证明，该工艺过程对小径原木的干燥是可行的。     

木材真空干燥的初步研究

本文研究木材真空干燥。内容包括木材真空干燥机的研制和木材真空干燥工艺的研究。试验结果表明,干燥机设计合理,技术性能良好,能够满足科学研究和小型生产的需要。通过实验,提出榆木、水曲柳、桦木和椴木的干燥基准,证明用真空干燥法干燥厚阔叶树材,具有干燥时间短、干燥质量好的优点。真空干燥具有研究价值,值得在一定范围内推广应用。     

新式木材干燥机

由中央木材机械加工研究所设计的СПВД201型木材真空干燥机已在《红十月》试验工厂投产使用。干燥机可供任何树种和任何断面的成材进行快速的、高质量的干燥和给车间采暖提供热量。该机适用于产量为5～10千米~3/年及缺少蒸汽锅炉设备的企业。干燥机系由罐体、真空系统、具有电极的高频发生器及操作过程的控制仪表等主要部件所组成的工艺和动力设备的总成。     

白桦小径原木干燥技术的研究

白桦小径原木干燥技术的研究朱政贤，艾沐野，庄茂成，马国凤，陈广元，张晓峰，张忠敏，赵如旭近年来，大径级优质木材资源日渐减少，而小径劣质优用木材如白烨日渐增多。白桦小径木很多用作地板块，包括立木地板块和工艺地板块。利用白烨小径原木制作上述地板块的干燥工...     

基于Android平台的木材材积计算器设计与实现

该文提出了基于Android手机的木材材积计算器的设计与实现,该方法可以计算国内原木、小径原木、长原木、短原木、原条、杉原条、马尾松原条、小原条、椽材及规格锯材的材积,免除繁重的查表任务,实现了木材材积更加便捷的野外实时计算。     

紫椴小径材高温干燥工艺的研究

为了合理开发利用紫椴小径材,对其材性进行了研究,进而解决干燥工艺,提高干燥质量。通过研究小径材的构造和物理力学性能,并和成材作比较,研制高温干燥基准,提高紫椴小径材的干燥合格率。一、试材、试验设备及方法试材采自黑龙江省尚志县东北林业大学帽儿山林场,条件见表1。试验设备利用自行研制的间歇式电热真空干燥机,工艺试验共进行三次,每次均对试材进行质量统计,测试试材缺陷。选取5块试验板,3块含水率检验板,包括心材板、边材板、应力检验板各1块。检验板和试验板端头用铝箔纸封涂,检验板每4h称重一次。     

电加热滚筒干燥机的结构设计与运动学分析

为发展间伐材木丝、木屑加工技术,满足木丝、木屑的干燥需要,根据干燥物料的特性,采用新型的干燥原理设计了一种电加热式的滚筒式干燥机。根据滚筒干燥机的工作特点,经过分析设计出滚筒的结构、环形保持架的结构、发热管支座的结构、进料斗和出料斗的结构。分析干燥过程中物料在滚筒中的运动过程,就该滚筒干燥机的工作过程中干燥的物料特性,进行运动学分析,通过理论计算得出干燥机滚筒转动的最小速度应该大于33.78 r/min,最大速度应该小于54.8 r/min,为干燥机的测试提供了理论依据。     

小径木半圆指接数学模型及出材理论

【目的】采用半圆指接工艺对小径木进行拼接加工,以拓宽小径级木材利用范围,提高小径木出材率。【方法】以理想原木为基础,建立小径木半圆指接数学模型。以圆心角60°去板皮拼接,求出小径木材积、板皮材积、指接铣去木材材积后得到小径木有效材积。选取直径120～190 mm的小径木,通过实际测量5组小径木长径和短径,分别计算出小径木半圆指接出材率。【结果】指接材出材率随直径增加而增大,当直径为190 mm时,根据理想数学模型求出小径木材积为32 022. 51 mm~3,由板皮材积模型求出其去除板皮材积为966. 46 mm~3,依照指接数学模型得出指接处需要铣去的废料材积为3 907. 93 mm~3,基于以上数据求出小径木半圆指接出材率为84. 78%,其出材率最高。【结论】采用半圆指接加工工艺,可提高小径木出材率;建立小径木数学模型、小径木半圆指接数学模型及相关材积公式,可为相关研究提供理论基础;选择的直径越大,出材率越高,可为实际选材提供参考。     

小径木双面连续式薄木纵向刨切机的出材率分析

针对新型纤维化单板重组木工艺,设计研发出单板刨切机,建立其在理想状态下的小径木数学模型。并且通过分析利用薄木刨切加工方式的小径木横截有效面积、实际测量及理论计算,得出在理论状态下4组选定的薄木刨切出材率分别为52.6%、76.0%、84.8%和89.1%。利用实验数据绘制出小径木半径与出材率关系曲线,计算出小径木双面连续式薄木刨切机的平均出材率为75.6%。     

速生人工林桉树原木锯解与干燥技术

速生人工林桉树原木生长应力大、径级较小,在锯解过程中易产生端裂和翘曲,在干燥过程中容易出现皱缩、开裂等缺陷,同时,还存在小径级原木出材率低、干燥板材降等问题。针对以上问题提出了翻转下锯法、自然气干+窑干+喷蒸调湿处理的联合干燥技术。     

REVIEWS—RESENSIES

The effect of various conventional seasoning treatments, restraint, storage, log diameter and position of boards in logs on the twisting behaviour of 19–20 year old P. patula timber was determined. The results indicate a distinct influence of restraint and to a lesser extent of temperature on twist, especially so on boards containing pith associated wood of the 27–36 em diameter class and all the boards, regardless of board position in the log, of the 17–23 em diameter class. The benefit of reduced twist through the application of restraint and higher temperatures was generally maintained after a 12 months storage period. It seems as if P, patula boards remain fairly stable during storage when only small moisture changes take place in the timber but the boards of the 17–23 em log diameter class and especially those containing pith associated wood, increased by 3–6° in twist with a loss in moisture content of only 3%.     

On the loss factor of wood during radio frequency heating

 The radial direction loss factor of full-size western hemlock sapwood and heartwood, as well as western red cedar heartwood timbers was measured using the direct calorimetric method with a laboratory-scale radio frequency/vacuum dryer at the frequency of 13.56 MHz, moisture content range between 10 and 80%, temperature range between 25 and 55 °C, and root mean square (rms) electrode voltages of 0.8 and 1.1 kV, respectively. The results indicated that the moisture content, temperature, electric field strength and wood type significantly affected the loss factor. Empirical regression equations were derived based on the experimental data that made possible the calculation of the loss factor and power density within wood during RF heating. Received 18 January 1997     

Technological properties of glulam beams made from hydrothermally treated poplar wood

In this research, technological properties of glulam beams made from hydrothermally treated poplar (Populus deltoides) wood were investigated. Poplar wood blocks with dimensions of 6 (r)?×?10 (t)?×?73 (l)?cm³ were cut and hydrothermally treated in a stainless steel reactor at temperatures of 140 and 160°C for a holding time of 30?min. The treated wood blocks were initially air seasoned and then they were dried in a semi-pilot scale vacuum dryer to achieve moisture content (MC) of 12%. Conditioning of the treated and the untreated wood blocks was done prior to adhesive bonding. Afterwards the glulam beams (4 ply) were manufactured using polyurethane. In order to evaluate the physico-mechanical properties of the beams, density, equilibrium moisture content, water repellent effect (WRE), anti-swelling effect (ASE), mass loss (ML), wettability as well as surface roughness due to the hydrothermal treatment were determined in the treated wood and delamination, bond shear strength, tensile strength, MC and moisture-induced stresses as well as strains in cross-section of the beams were determined in the glulam beams. The results revealed that density, ML, ASE, WRE, modulus of elasticity, modulus of rupture and delamination were increasing and the others were decreased due to the hydrothermal treatment.     

Windthrow and recruitment of large woody debris in riparian stands

To document the impacts of windthrow in riparian leave strips and identify the components needed for small stream large woody debris (LWD) recruitment modeling, we monitored nine small streams at a temperate rainforest site in coastal British Columbia. This study was a component of a larger integrated study of forest management impacts on small streams. A series of small clearcuts were harvested in 1998 in a 70-year-old second growth stand that had regenerated naturally following logging and wildfire. Three cutblocks each were assigned to 10 m and 30 m buffer width treatments and three areas were assigned as unharvested controls. Seven years after the 1998 logging, all logs greater than 10 cm diameter that spanned at least part of stream channel width were measured. A total of 179 logs were recorded. Post-harvest windthrow was higher in the 10 m buffer treatment, while competition-related standing tree mortality was higher in the controls. The major windthrow events had occurred in the first and second years after logging of adjacent stands. There was no significant difference in the number of spanning and in-stream logs in the 10 m, 30 m buffer and control treatments. More than 90% of the LWD was in the 10–30 cm diameter classes. The majority of logs were oriented perpendicular to the stream channel. At the time of measurement, the majority of these trees were still suspended above the stream channel, indicating that the recruitment of logs into the stream channel is a long-term process. Time to recruitment into the channel is dependent on log and valley geometry, log size, species, and log condition prior to toppling. Log height above stream was negatively correlated with log decay class and valley width. Log length was negatively correlated with state of decay, and many windthrown logs were in an advanced state of decay before they entered the stream.     

小径柞木真空干燥应力的试验研究

在真空干燥条件下,分析小径级柞木板材的应力与含水率、时间的关系,结果表明:在低温条件下,由于真空负压作用,水分蒸发速度得到了加快,干燥应力由于干燥前板材内的初始应力的差异,导致干燥过程中应力的发生、发展有所差异。根据应力表现的差异应当在干燥不同阶段及时进行调湿处理,预防板材开裂产生。     

5个尾巨桉无性系材性、单板生产与价值的研究

对5个尾巨桉无性系的原木旋切单板的研究表明,5个无性系的木材密度、应力波传输速度及原木端裂指数、出材率、原木价值及单位材积原木的单板价值方面均存在差异。单板出材率从高至低的顺序是DH32-28>DH61-1>DH32-26>DH33-27>DH15-3,原木生产单板价值从高至低的顺序是DH61-1>DH32-26>DH32-28>DH33-27>DH15-3,单位材积原木生产的单板价值从高至低的顺序是DH32-28>DH32-26>DH61-1>DH33-27>DH15-3。影响单板出材率的主要因子是原木的弯曲度;影响原木单板产品价值的主要因子是大头直径、小头直径、最小小头直径和木材密度;影响单位材积原木的单板产品价值的主要因子相关性从大到小依次是木材密度、弯曲度、小头最小直径和端裂指数。从小头最小直径能较好地预测原木的价值,相关系数达0.8949;小头最小直径和弯曲度可以预测单位材积原木的单板产品的价值。建立的5个回归方程为原木分级和定价销售提供了依据。无损检测立木木材密度(Pilodyn测定值)和应力波传输速度能够较好地预测原木端裂指数,但是并不能由此预测单板出材率或原木价值。本研究为通过育种和营林措施培育高价值胶合板单板用尾巨桉木材提供基础数据。     

不同浸渍处理方式对毛竹淀粉含量的影响

采用常压水浸渍、真空水浸渍、常压碱液浸渍3种浸渍方式对毛竹进行处理,探讨不同浸渍方式对毛竹中淀粉含量的影响。研究结果表明:竹材内淀粉含量随着浸渍处理时间的延长而减少,经过120 h浸渍后,毛竹中的淀粉含量从高到低依次为常压水浸渍、真空水浸渍、常压碱液浸渍。在相同碱液浓度的条件下,毛竹中的淀粉含量随着浸渍时间的增加而减小。经过120 h的碱液浸渍处理,碱液浓度最大(1.5%)的组溶解抽提出来的淀粉含量最多。真空水浸渍可以降低毛竹中的淀粉含量,但不同真空压力之间对淀粉含量的影响不大,真空压力对淀粉含量的影响有效时间为72 h以内,超过72 h淀粉含量减少缓慢。     

国外产8个竹种种子品质研究

对外国产3个属8种竹子种子的形状、颜色、大小等形态特征指标和种子的千粒重、纯净度、病虫害感染度、含水量、发芽率等质量指标进行了研究。结果表明:1)带壳颖果形状多为圆锥形、纺锤形,颜色以褐色、黄褐色、灰褐色为主,长度和直径分别为9~11 mm和1~4 mm;去壳颖果长度和直径分别为8~15 mm和1~3 mm;颖果种子的千粒重、纯净度、含水量、病虫害感染程度、实验室发芽率、温室发芽率分别为10~70g、70%~93%、0%~15%、7%~8%、40%~75%、70%~95%。2)带壳坚颖果的形状一般为卵圆形,颜色多以灰褐色为主,长度和直径分别为5~8 mm和2~5 mm;去壳坚颖果长度为4~8 mm,直径为2~4 mm;坚颖果种子的千粒重、纯净度、含水量、病虫害感染程度、实验室发芽率、温室发芽率分别为10~35g、85%~89%、6%~9%、0%、15%~50%,25%~69%。     

干燥条件对小径桦木干缩性能的影响

根据在大气及干燥室等不同干燥条件下的试验，探讨了小径桦木干缩性能的变化规律。为合理选择和制定小径桦木干燥基冷提供理论依据。     

人工林小径落叶松集成木梁试验研究

以人工林小径落叶松为原料,研究其异型单元材下锯法,与传统的锯割工艺相比,出材率和综合利用率均有提高;研究异型单元材胶合技术,开发结构性能优良、附加值高,能满足轻型木结构用材标准的集成木梁,为人工林小径木用于轻型木结构建筑和优化集成木梁生产工艺打下基础.