关于“七五”期间我国制材工业自动化问题的探讨

一、前言制材是木材加工工业的基础。搞好制材生产对于扩大森林资源的利用,提高木材利用率具有重要意义。影响制材产品的主要因素是制材工艺和机械设备。当前我国制材工业的技术装备是比较落后的,它直接导致了制材产品质量低劣,据有关部门统计,制材产品合格率仅达70％左右。     

削片制材——制材生产发展的重要途径

本文分析了我国森林资源概况及木材供求的总格局,根据木材资源的结构与特点,对推广应用削片制材技术的必要性、工艺与设备、先进合理性进行了论述。并结合制材生产现状对应用该技术存在的问题提出了方法与建议,阐述了推广、应用削片制材技术对制材生产发展的重要意义。     

我国制材工艺和制材模式的现状及发展趋势

介绍了我国制材工艺发展状况及带锯、圆锯、框锯、削片制材4种主要制材模式,阐述了制材设备的发展方向,指出制材工艺与制材模式必将向着满足高生产率、高出材率、高木材利用率、高成材质量、高附加值和多产品品种加工的方向发展。     

采用新设备新技术发展削片制材

当前，结合我国林木资源特点和技术的发展，借鉴世界先进国家制材工业发展经验，采用新设备、新技术更新改造旧有落后的传统制材设备和工艺，针对人工林，中、小径级原木发展削片制材，扩大产品品种，提高木材的综合利用率，赶超世界先进水平，是我国制材工业正确的发展方向。     

简谈现代制材技术发展

目前就世界范围来说,有三种不同的制材方法,即框锯、园锯、带锯制材。除此之外,又增加了第四种制材设备,这就是原木削片制材联合机,这种联合机械可以说是木材综合利用工业(制材、造纸、纤维板和刨花板工业)发展的必然结果。本世纪中叶,制材技术同其它许多工业领域一样,进展较为缓慢,1950年后显得发展较为迟缓,主要是平稳地前进而缺乏或甚至很少有跃进局面。明显的是受制材机械的发展水平所限制,     

我区林产工业应以人造板为发展方向

人造板是高效利用木材资源的主要方式,是木材工业中高增值、高技术含量的主要产品.由于在世界范围内人造板原料由利用天然林资源为主,向利用人工林资源和各种非木材植物纤维资源为主的方向转变,其产品又可以代替天然的大径材.因此,在森林资源锐减的今天,国内外都非常重视人造板工业的发展.我区是林业大省(区)之一,森林资源比较丰富,仅大兴安岭林区每年各种森工生产剩余物就达100万立方米.白桦是发展胶合板的优质材种;兴安落叶松生产的纤维板、刨花板、华夫板、中密度纤维板质量好、强度高,深受用户欢迎.为使我区林业在现有条件下,变资源优势为经济优势,走出低谷,跻身于国内前列,笔者认为人造板是我区林产工业的发展     

采用新设备新技术发展削片制材

当前，结合我国林木资源特点和技术的发展，借鉴世界先进国家制材工业发展经验，采用新设备，新技术更新改造旧落后的传统制材设备和工艺，针对人工林，中，小径级原木发展削片制材，扩大产品品种，提高木材的综合利用，直超世界先进水平，是我国制材工业正确的发展方向。     

从木材工业内涵的不断扩大看木工机械的发展

传统的木材工业是以制材工业、实木制品工业为主的，因此木工机械的发展主要以制材设备（木工带锯机、圆锯机、框锯机等）和细木工。设备（木工刨床、铣床、车床、开榫机等）为主。随着木材工业的发展，天然林资源的严重枯竭，出现了木材长期供不应求的局面，迫使木材工业内涵不断扩大二形成了新的产品结构。使单一的锯材产品转化为单板、纤维、刨花、木片、木基复合材等产品，以实现木材资源的充分合理利用和高效利用。使木工机械的发展朝着提高木材利用率、提高木材加工精度、提高生产效率和自动化程度的方向迈进。１木工机械产品种类的发…     

我国木材制材业发展探讨

本文就我国森林资源与木材供需矛盾问题，从提高木材综合利用率和出材率入手，论述了我国制材工业现状和国外几种先进制材方式，阐述了改变我国制材工业落后现状的设想。     

我国木材工业发展战略的基本思路

木材工业是采用机械、(或)物理、化学方法加工处理木质材料或木质材料与其它材料构成的复合材料,制成仍保有木材基本特性产品的加工工业.木材工业包括制材,木材干燥,木材防腐,木材改性加工,木制品及家具制造,人造板制造(包括胶粘剂制造)和人造板的功能性加工、装饰加工及应用加工,装璜业,木片业等.它与林产化学工业、木浆造纸工业同为木材采伐运输工业的后续工业,是木材综合加工利用,增加木材附加值的重要工业部门.木材工业与林产化学工业、木浆造纸工业做为森林资源利用的环节是森林资源经济价值的主要体现,是补偿森林资源再生产的物资前提,是整个林业产业的龙头产业.同时,发展木材工业、林产化学工业和木浆造纸工业还可以促进造林绿化朝着定向化、基地化、工业化和商品化的方向发展.     

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.     

Simulated yield and quality distribution of sawn timber from final felling in a Norway spruce [Picea abies (L.) Karst.] stand with varying thinning regimes: A case study

Abstract

An integrated simulation tool, formed by integrating the InnoSIM sawing simulation system with the RetroSTEM simulator, was used to convert available wood raw materials from final felling into sawn timber, allowing for calculation of the three-dimensional wood properties of individual stems (stem geometry, heartwood formation, knottiness) as well as the volume, quality and value of sawn timber in a Norway spruce stand with different thinning regimes (unthinned, normal and intensively thinned). Based on the input data of sawing patterns, the simulations indicate that there are relatively small differences (<8%) in the volume yield (m³ha^?1) of sawn goods resulting from sawlogs available from final felling with different thinning practices. However, intensive thinning yielded the largest stem diameters and the greatest volumes (m³ha^?1) of large-sized centre goods (thickness: 50, 63, 75 mm) of rather poor quality. Normal thinning yielded the largest volume of A-grade side boards and centre goods (m³ha^?1), as well as the best total value ([euro]ha^?1) of sawn timber. Differences observed in sawn timber quality distribution can contribute to even more significant variation in value yields, if pricing mechanisms of timber products change to favour higher grade timber products.     

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.     

Automatic detection of washboarding in bandsaws

This paper presents an on-line method for detecting washboarding generated in bandsaws. It uses a parameter based on the shape of sawing force amplitude distributions. The curve of the probability density function of the parallel sawing force amplitude obeyed a normal distribution for the normal sawn surface, but it changed to an M-shaped distribution when washboarding appeared on the sawn surface of the workpiece. The curve of probability density function of the normal sawing force amplitude obeyed the normal distribution for any sawn surface investigated. The workpiece including a knot did not influence use of the parameter for detecting the appearance of washboarding.     

Potential for increasing volume yield by reducing planing allowance

About half the volume of sawlogs ends up as sawn and planed timber. The rest is lost due to drying shrinkage or is turned into by products. As the raw material is a major expense for a sawmill, it is important to reduce waste. To investigate how much the volume yield in the production of sawn and planed timber could be increased by reducing the target dimensions in the sawing stage in a sawmill, two groups of sawn timber were planed under similar conditions. One group consisted of sawn Scots pine timber with a large variation in twist. The other group consisted of sawn Norway spruce timber planed under different pressure settings. Using X-ray images, the minimum dimension for avoiding planer misses was calculated for each board, to find the smallest green target dimension. This was compared to actual measured dimensions. It was found that most sawn timber had unnecessarily large dimensions, and it was also found that a reduction in the target dimensions could increase the volume yield for sawn and planed timber by more than 3 percentage points. Boards with large twist would however need a higher planing allowance. The effect of the planer pressure setting was negligible.     

国产MJ3210小型木工跑车带锯机锯解正交试验分析

采用正交试验设计法，对国产MJ3210小型木工跑车带锯机的锯解质量进行研究。通过实测马尾松锯材尺寸偏差、表面粗糙度等参数，得到其最佳的进料速度、锯解厚度和锯卡高度的组合方案。结果表明，该设备具有结构简单、出材率高、锯解精度高、质量好、成本低和生产效率高等优点。     

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.     

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。     

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.     

控制锯材变形的方法

针对影响锯材变形的因素。从降低原木残余生长应力、对干缩湿胀和干缩应力的干燥工艺处理，到下锯法的合理选择，以及通过木材改性达到尺寸稳定等几方面进行了全面探讨，为提高锯材和木材品产品质量供参考。