旋切原木六点定心理论的研究

在单板旋切中 ,选择最佳的定心点是旋切优化的最关键技术。本文在原木三、四点定心理论的基础上 ,提出了旋切原木六点定心理论。该理论是在原木的任意截面上取 6个点 ,由这 6个点回归出原木内包络圆柱的最佳圆心轴线 ,为高精度原木定心机的数控化提供先进的基础理论 ,提高原木的定心精度和单板的出材率及成品单板的合格率。使原木的定心理论提高到一个新的水平。     

弯曲枕资下锯图的研究

本文应用计算机辅助设计弯曲枕资下锯图，建立了辅助设计的数学模型，并编制了Ｃ语言程序，为合理加工弯曲枕资，提高出枕率、综合出材率和产品经济效益提供了理论依据。     

弓形弯曲原木优化下锯建模与仿真

面对我国森林资源不足、质量不高的状况,建立和应用原木优化下锯理论,提高木材出材率已成为缓解木材供需矛盾的主要途径.本文通过提出弓形弯曲原木的数学模型,全面描述弯曲原木的解析形状,并对弯曲原木的主产出材率进行优化设计,借助计算机辅助设计实现原木优化下锯的三维再现,这对提高原木出材率和利用率、提高木材加工技术水平与现代化程度有着极为重要的实际意义和广泛的应用前景.     

关于原木价格率与锯材经济定额的研究

为使锯材生产取得良好的经济效益,有必要制定锯材经济定额,用以衡量锯材生产的经济效益和提高生产的管理水平。我厂在1982年初制定了原木价格率及锯材经济定额(以下简称:价格率经济定额)。它是依原木树种、材长和等级的不同,求出不同种类原木价格差异制订的。我厂实行一年多的结果证明,这种方法能够提高经济效果,明确经济责任,有效地改善和提高企业管理水平。     

谈林区贮木场原木剥皮的必要性

1原木剥皮的必要性林区的贮木场，是使林木先成采伐和运输最终形成商品材的原木存贮处。随着社会主义市场经济的到来，愈显示出其重要地位。贮木场的另一功能使是木材加了生产的第一个阶段，为木材加丁准备原料。贮木场的基本任务是采取一切必要和可能措施，尽可能提高经济材出材率和木材利用率，提高原木等级车或产品的经济价值。从此意义而论，可以将贮木场理解为木材加丁的第一车间、此外．贮木场也是国库所在，存贮保管着国家的重要物资。与此同时，贮木场及时纳州、发运和销售木材。原木作为商品向外界批发和零售，因此，它又是一个大…     

原木两开材与三开材出板率的比较分析

对３０－５０ｃｍ直径中每两根相近的原木采用两开与三开的制材方法进行锯解。两种制材方法是得到的木方采用相同的煮木工艺、创片技术、贴面方法进行生产，贴成相同规格的贴面板。统计分析证明，三开材的原木出板率、木方出板率、相对出板率均高等两开材。这主要是因为两开材有较多的边材作为废料被丢弃，而三开材的边材则最大限度地得到了利用。     

芬兰原木销售创10年来的最高水平

芬兰：芬兰农林产品中央联盟（MTK）报道称，上周原木销售量提升到了一个新的水平，这是10年来未曾见过的。7月份芬兰政府为了确保为本国的森林工业提供足够的原料，在原料销售领域推出了一项新的鼓励税率措施，这也是芬兰政府对俄罗斯决定提高原木出口税率和部分本国的森林拥有者消极销售所做出的回应。     

二次曲线在原木外形拟合中的应用

介绍一种利用离散样点拟合原木外形的抛物线参数拟合法。根据原木断面上的少量样点数据，可以准确拟合出原木断面实际形状。模型计算速度快，累积误差小，曲线平滑。利用Ｃ语言强大的绘图功能，在计算机上给出经拟合的原木断面轮廓。为锯部优化提供了逼真的原木模型     

短周期工业用材多锯片剖分过程的数学模拟研究

采用截顶椭圆一抛物面原木数学模型，应用原木的四个实测参数，测定出经多锯片裁分锯剖分的各块毛边板、板皮的精确材积；精确算出锯路的损耗和出材率。应用本文提出的理论，可以设计出简单的多锯片裁分锯数控检测系统，使短周期工业用材加工实现数控化。     

壳聚糖处理对木材染色的助染效果及其机理的研究

采用酸性染料酸性橙Ⅱ对经壳聚糖处理的毛白杨原木木粉、苯醇抽提木粉以及木材主要组分进行染色，并用等物质的量的强碱、弱碱、强酸、弱酸以及水和有机溶剂处理相同质量经壳聚糖处理的原木木粉与壳聚糖染色试样，测定其助染效果和确定其助染机理。结果表明：壳聚糖处理能显著提高酸性染。料对毛白杨原木木粉、苯醇抽提木粉、纤维素、半纤维素和木质素的上染率，其助染机理是与木材组分结合的壳聚糖分子的氨基与酸性染料上的磺酸基以离子键结合，形成磺酸盐，从而提高了上染率。     

Log sawing positioning optimization and log bucking of tropical hardwood species to increase the volume yield

The sawmill industry is a very important link in the Mozambique forest products value chain, but the industry is characterized by undeveloped processing technology and high-volume export of almost unrefined logs. The low volume yield of sawn timber has been identified as a critical gap in the technological development of the industry. To improve the profitability of the industry, there is thus a need to develop methods and techniques that improve the yield. In this paper, different positioning of logs prior to sawing and the possibility of increasing the volume yield of crooked logs by bucking the logs before sawing have been studied. A computer simulation was used to study the cant-sawing and through-and-through sawing of the logs to determine the volume yield of sawn timber from the jambirre (Millettia stuhlmannii Taub.) and umbila (Pterocarpus angolensis DC.) species. The optimal position, i.e. the position of the log before sawing that gives the highest volume yield of sawn timber for a given sawing pattern when the positioning parameters, offset, skew and rotation, are considered gave a considerable higher volume yield than the horns-down position. By bucking very crooked logs and using the horns-down positioning before sawing, the volume yield can be of the same magnitude as that obtained by optimal positioning on full-length (un-bucked) logs. The bucking reduces the crook of the logs and hence increases the volume yield of sawn timber.     

不同下锯法锯解的分析评价

本文就制材生产中通常使用的三种下锯法,采用计算机进行模拟锯解,然后进行分析评价,找出三种下锯法对主产锯材宽度、原木出材率和经济效果的影响。为合理利用原木、选择适当的下锯法,提供了理论依据。     

Variation in log quality and prediction of sawing yield in oak wood (Quercus robur)

Context

The commercial feasibility of sawmilling depends on the expected volume and value of sawn planks. Models that predict the volume of sawn timber of a particular quality and produced from logs of known characteristics are therefore very useful.

Aims

The objectives were to study variation in sawing yield and to obtain models that predict lumber volume and grade recovery on the basis of easy-to-measure predictor variables of saw logs.

Methods

Forty-six oak trees growing in Galicia (NW Spain) were felled and cut into logs. The logs were visually graded and sawn mainly into quartersawn planks, which were dried, planed and visually graded for structural purposes.

Results

The total volumetric sawing yield was 47.6 %. The sawing yield for planks of structural dimensions (cross-section, 70?×?120 or 70?×?170 mm) was 43.4 %, but decreased to 8.4 % for structural sized and quality grade beams because of wane and biotic damage in many pieces. Log grade did not significantly affect sawing yield in the sample analysed, despite the wide range of diameter over bark at the smallest end in the sampled logs (22–77 cm). The sawing pattern affected total sawing yield (F?=?4.913; p value?=?0.001) and the sawing yield for structural planks (F?=?6.142; p value?=?0.0002); radial sawing with one cut and live sawing of half logs provided the highest yields. Three models were proposed for estimating sawn volume in timber products, with the small-end log diameter over bark as the predictor variable and R _adj ² between 0.31 and 0.78 (p value?<?0.01).

Conclusion

For the purpose of producing oak timber destined for structural use, the presence of bark and sapwood in planks must be reduced in the sawing process; this would decrease the total lumber recovery but increase the timber value yield. Air drying must be accelerated to reduce biotic damage in sawn planks. Geometric mean diameter over bark at the smallest end (d) outperforms other measures as a predictor variable for total or structural sawn timber volume.     

Simulation of the yield of knot-free components from Scots pine (Pinus sylvestris L.): A comparative study of star-sawing and square-sawing

The production of knot-free wood is important since the market demands wood without knots for reasons of both appearance and material properties. This work describes a simulation of the removal of knots from star-sawn and square-sawn timber. The efficiency of the two methods is compared in terms of the length of the knot-free components obtained and the volume yield. The simulation was based on data for trees and logs taken from the Swedish Stem Bank. These data were then used to simulate the sawmill process in a computer program called the Virtual Sawmill. Data related to the boards obtained were used in a MATLAB model simulating the cross-cutting of knots. Simulated star-sawing of logs with a top diameter exceeding 230 mm gave a mean knot-free component length of 417±321 mm, while the mean length of knot-free components for simulated square-sawing of the same logs was 298±122 mm. The volume yield of knot-free components from the two sawing patterns was 91% for star-sawing and 87% for square-sawing. For timber with cross-section dimensions of 38×75 mm², the mean length and yield of knot-free components from simulated star-sawing were 451±349 mm and 90%, respectively. In simulated square-sawing, the corresponding values were 263±197 mm and 82%, respectively. This shows that star-sawing has potential for the production of knot-free timber.     

Sawing patterns for large-diameter sugi (Cryptomeria japonica D. Don) sawlogs: Current status and future outlook

Abstract

A survey was conducted at nine sawmills in Japan to evaluate and compare the sawing of sugi (Cryptomeria japonica D. Don) logs of 30 cm and more in diameter. The purpose was fourfold: (1) to document sawing patterns appropriate to the large-diameter logs; (2) to examine the composition of wood components (structural, nonstructural, and fixtures) produced from those patterns; (3) to investigate log and product prices; and (4) to ascertain distances to the log supplier and product markets. Impetus for the study arose from a forecasted shift in the diameter distribution of plantation trees in Japan; from small and medium-sized logs to large-diameter logs. With an overabundance of large-diameter domestic logs forecasted within the next decade, the need to understand how to best utilize and effectively process the large-diameter resource is of utmost importance.     

Simulation of the yield of knot-free components from Scots pine (Pinus sylvestris L.): A comparative study of star-sawing and square-sawing

Abstract

The production of knot-free wood is important since the market demands wood without knots for reasons of both appearance and material properties. This work describes a simulation of the removal of knots from star-sawn and square-sawn timber. The efficiency of the two methods is compared in terms of the length of the knot-free components obtained and the volume yield. The simulation was based on data for trees and logs taken from the Swedish Stem Bank. These data were then used to simulate the sawmill process in a computer program called the Virtual Sawmill. Data related to the boards obtained were used in a MATLAB model simulating the cross-cutting of knots. Simulated star-sawing of logs with a top diameter exceeding 230 mm gave a mean knot-free component length of 417±321 mm, while the mean length of knot-free components for simulated square-sawing of the same logs was 298±122 mm. The volume yield of knot-free components from the two sawing patterns was 91% for star-sawing and 87% for square-sawing. For timber with cross-section dimensions of 38×75 mm², the mean length and yield of knot-free components from simulated star-sawing were 451±349 mm and 90%, respectively. In simulated square-sawing, the corresponding values were 263±197 mm and 82%, respectively. This shows that star-sawing has potential for the production of knot-free timber.     

径切板生产新工艺和新设备的研究

建立了１１种径切材下锯模型，并利用图像处理及曲面拟合方法将得到的任意形状原木进行模拟锯割，结果表明，用三开法生产径切板及旋切薄木具有较高的出材率。研制了专门用于生产三开材的剖料锯机及生产工艺。在现有的带锯机前安装该剖料锯机即能利用现有锯机和跑车生产径向材。     

Combined production of sawn timber and firewood billets at a birch sawmill in Finland: A simulation approach

Abstract

Growing markets for chopped firewood have created alternative uses for the by-products of sawmills. Based on empirical data and simulated results, the potential of birch (Betula pendula Roth, Betula pubescens Ehrh.) from commercial thinnings for combined industrial production of sawn timber and firewood billets was investigated. In the simulations, different sawing patterns were used for logs intended to combine production of sawn timber and billets for chopped firewood (‘sawlogs’), and for logs intended only to firewood production (‘firewood logs’). Finally, economical feasibility analysis was done concerning the differences between the sawmills’ traditional business concept and the novel concept combining sawn wood and firewood production. The bucking results for the volume yield of different timber assortments varied only slightly between the different bucking options, i.e. the combinations of timber assortments. The main differences in the volumes of timber assortments were due to the stand type where the birch trees were sampled (planted, naturally regenerated, mixed birch–spruce). In the sawing procedure, the output of sawn timber varied between 24% and 42% of the log volume in the sawlogs, depending on the log diameter class. As the volume yield of sawn timber and firewood billets was counted together in the case of sawlogs, the log consumption was c. 1.75 m³ of roundwood per 1 m³ of sawn timber and firewood billets. In the case of the firewood logs, the log consumption rate was considerably lower, only c. 1.35. The economic calculations showed that using the firewood approach in sawing may increase the net added value of products by €1.9–5.4 m^?3 of logs, depending on their diameter class. As a conclusion, parallel production of sawn timber and firewood from logs from the first and second commercial thinning of birch-dominated stands is a concept that could work as an alliance between a sawmiller and a firewood entrepreneur. The concept could be competitive compared with both traditional sawmilling and production of chopped firewood.     

双联圆锯径切板优化下锯研究

面对我国森林资源不足、质量不高的状况,研究和应用优化下锯理论实现原木最优下锯,提高木材出材率已成为缓解木材供需矛盾的重要途径之一。本文提出了以最优化技术为基础的原木优化下锯法,以最小余料为目标函数的原木优化下锯方法,采用解析法建立原木优化下锯数学模型,通过计算机辅助排样求解,得出了一种基于梯形下锯法锯切原木的优化下锯算法,为数控双联圆锯径切板优化下锯提供了数学方法和基础,并给出应用实例。     

Log sawing position optimization using computed tomography scanning

When disjoining a log, several factors affect the value of the sawn timber. There are log features, such as outer shape, knots, rot, and so on. There are also sawing parameters, such as sawing pattern, log position, and so on. If full information about log features is available, sawing parameters can be adapted in order to maximize product value in sawmills. This is soon possible, since computed tomography (CT) scanners for the sawmill industry are being realized. This study aimed at investigating how CT data can be used to choose rotational position, parallel displacement, and skew of sawlogs, to maximize the value of the sawn products. The study was made by sawing simulation of 269 CT scanned logs of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] H. Karst.). The results showed that value recovery could be improved by 13% in average, compared to a sawing position based on log outer shape, and 21% compared to sawing logs centered and horns down. It can be concluded that a CT scanner, used in a sawline to optimize sawing parameters, has a large potential for increasing value recovery and thus profit.