基于UG的木工铣刀CAD系统设计

以UG为支撑平台,利用Visual C 6.0、SQL Server和UG二次开发工具UG/Open研制开发了现代木工铣刀CAD系统.该系统界面友好,集现有木工铣刀查询、选型、设计计算和三维建模于一体,同时又具备良好的可扩展性和可移植性.实践证明该系统极大地提高了现代木工铣刀的设计效率和精度.     

木工刨床的空转噪声及对人与环境的影响

本文从人一机一环境系统角度出发，以ＭＢ１０６Ａ型木工压刨床为例，通过对其空转噪声及机床操作者心率的实测，系统地研究了木工压刨床本身一些因素对木工压刨床空转噪声的影响；同时也研究了机床空转噪声与传播距离的关系；最后研究了木工压刨床噪声对机床操作者心率的影响。同时分析了噪声产生的机理，并进行了试验论证，最后建立了木工压刨床空转噪声的数学模型，从而为木工机床的研究与设计及人一机一环境系统工程的研究提供了依据。     

数控木工机床的外观设计原则

数控木工机床是近几年木工及家具机械行业出现的新产品，代表了木工机械行业的发展趋势。为了使数控木工机床能够体现更先进、更人性化与环境更协调的现代化设计理念，本文就数控木工机床的外观设计原则做了必要的讨论。     

一种新型木工带锯机问世

日前，一种新型木工带锯机──MJ316台式木工带锯机在省林机厂问世。这是该厂科研人员为适应激烈的市场竞争和目前木材资源状况而研制出的一种新产品。投放市场以来，该机以其良好的使用性能，深受广大木材加工者的青睐，成为抢手货。这种新式木工带锯机是在原MJ318木工带锯机的基础上改进设计的。该机在整体设计、主要部件结构、技术参数和驱动控制等方面进行了大幅度的修改。在满足降低成本的前提下，尽量考虑技术先进、结构合理、操作调试简便，尽可能地提高银机的利用率。这种新型的木工带锯机可用于加工直径450毫米以内的圆木，制作…     

基于HNC-8的木工榫槽现场交互自动编程数控系统的开发

在分析木工榫槽加工特点的基础上设计了一种基于HNC-8（华中8型）平台面向专业木工榫槽加工的现场交互数控自动编程系统，其中的榫槽轮廓形状数据有两种输入方式：一种是采用直接读入标准的DXF文件格式，另一种是在用户界面上直接输入所需要的各种图元（诸如NURBS曲线、直线、圆弧、圆等构成的异形图元），然后系统根据工艺、加工参数快速生成加工代码直接进行加工。实际应用表明，系统工作可靠，能快速生成所需加工代码，提高了榫槽机的自动化程度。     

木工压刨床空运转振动状态的研究

木工压刨床空运转振动状态的研究李志仁，陈守谦，姜新波（东北林业大学哈尔滨１５００４０）关键词木工压刨床，振动状态，自功率谱，机内振源，刚度，动态设计木工压刨床是木材机械加工中使用数量最多，应用范围最广泛的一类机械设备，它不仅用于林业生产，而且在建筑、...     

木工榫槽铣刀的固有频率测试研究

分别采用随机激励功率谱和声学测量法测试木工榫槽铣刀的固有频率。结果表明，两种测试方法皆可行且安全可靠。对木工榫槽铣刀固有频率的测试研究可为木工榫槽铣刀设计与优化提供借鉴。     

我国木工跑车带锯自动摇尺型号与命名问题探讨

１　国内自动摇尺型号与命名概述我国木工机床的型号编制有专门的国家标准，归口到原机械工业部管理，而使用木工机床则主要在原林业部、物资部和轻工部等系统。我国定点厂生产的木工跑车带锯机按国家标准，都有完整的型号名称。例如，辽宁沈阳市带锯机床厂生产的ＭＪＢ３２１２型木工跑车带锯机；河南信阳木工机械厂生产的ＭＪＫ３２１２Ｃ数控跑车木工带锯机；四川岷江林业机械厂生产的ＭＪ（Ｚ）３２１０跑车木工带锯机；福建邵武木工机床厂生产的ＭＪ３２１０型跑车木工带锯机等。但构成跑车带锯的主要组成部分，号称带锯机心脏的自动摇…     

一种钣金件结构的木工多用机床

介绍了一种用钢板设计制造的轻便型木工具用机床，它解决了现有的中，小型木工用机床重量大，制造成本高。主要大件不具有互换性及搬运不便等缺点，因该机床中７０％以上的零件均采用２．５～３ｍｍ冷轧板冲压成形制造，故机床制造简单，重量轻及互换性强，因此该结构的木工多用机床具有广阔的推广应用前景。     

木工车床溜板箱的数控改造

对木工车床进行数控改造，不仅能提高生产率和加工件的尺寸一致性，而且能最大限度地发挥传统设备的作用。因此对上海木工机械厂生产的＊＊伽u。木工车床进行市数控改造。专门设计了四轴微机控制系统，并将原有的齿轮齿条传动装置改成丝杆螺母传动，实现了床面X、Z两轴和端面X’、Y’两轴的同时控制，使木工车床的加工效率提高了两倍。1车床结构的改进MCD616B木工车床溜板箱由0．37kw的交流电动机带动，通过齿轮齿条传动，只有三级进给速度，空行程速度太低，影响生产效率。通过改进，取消交流电动机和齿轮齿条传动机构，改成如图1所示…     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。