金属基金刚石砂轮电火花整形参数的研究

由于电火花整形法实现了对金属基金刚石砂轮的高效整形,使得金属基金刚石砂轮的应用逐步推广。本文主要利用电火花整形法通过试验分析放电参数对金属基金刚石砂轮整形精度和整形效率的影响,得出一组优化的砂轮整形参数。     

金刚石木工刀具刃磨技术发展前景

金刚石木工刀具常用的刃磨方法有机械研磨和电火花磨削,由于机械研磨效率低、金刚石层厚度不均匀等缺点,其应用受到很大限制.而电火花磨削工艺加工效率高,刀具平面度易于控制,近年来得到了迅速的发展.     

CTE500数控电火花成型机的使用与维护

介绍了CTE500数控电火花成型机的结构、技术参数以及机床主机安装和加工工艺参数的选择,对该机床常见故障原因进行分析并提出了解决方法,阐述了机床的操作要求和养护措施.     

电火花磨削刀具的步距伺服进给系统

电火花磨削刀具的步距伺服进给系统（１５００４０）东北林业大学郭彦玲，李瑞芬，佟小平，潘志然聚晶金刚石是目前最佳的刀具材料之一，也是难加工材料，其硬度高、耐磨性好，由于其具有微弱的导电性，故可用电火花放电加工。本系统采用电火花磨削对聚晶金刚石刀具进行加...     

单机鲁棒性最小提前期研究

现代加工制造生产实际生产环境中有很多不确定因素,为了提高企业生产效率,提高生产调度的稳定性,保证生产的有序、高效进行,针对订单式加工单机生产过程中新产品初始加工参数错误的情况,本文以最小提前期为目标,首先对鲁棒性测度进行说明,根据单机鲁棒性对其最小提前期进行确定,并且对问题进行分析,然后构建了以EDD为原则的初始调度模型与平均提前时间的优化调度模型。运用插入空闲加工时间的方法,保证优化调度满足鲁棒性测度,并且对初始调度方案以及优化调度方案通过Matlab软件分别进行模型仿真验证,仿真结果表明该方法应用下的优化调度模型的适用性和有效性。得到结论:该模型有效的支持最小提前期单机生产优化调度。     

CNC圆雕工艺参数对木制部件表面粗糙度的影响

CNC圆雕技术已被广泛应用,但业界对加工参数方面的研究比较少,大部分工人多是依靠自己的经验来设定参数,产品加工质量评定方法准确度不高。为探寻适合实木CNC圆雕雕刻加工规律,优化实木的数控雕刻加工质量,通过正交试验L_(16)(4~5)试验方案,针对树种、锥度球头刀刀尖直径、进给量及加工速度的工艺参数对木制部件表面粗糙度的影响进行试验研究,采用3D激光轮廓扫描仪对加工的木制部件的表面粗糙度进行检测。结果表明:刀具路径进给量的大小对圆雕制品的表面粗糙度、加工效率的影响较大;刀尖直径对部件表面加工质量及设备的加工效率有一定的影响;试验中所选择的加工速度对部件的表面粗糙度影响较小,树种对加工速度的影响主要取决于树种的构造及密度,对于密度低、纤维韧性好的树种,可适当提高加工速度,减少进给量来提高其表面加工质量。     

基于三维表面形貌测定法的水切割木竹材工艺参数优化

为优化木竹材超高压水射流切割加工工艺参数,以红橡木和竹地板为对象,采用正交试验法,研究磨料流速、切割压力、进给速度、靶距对水射流加工试件表面粗糙度的影响,探索优化工艺参数。利用扫描探针式三维表面形貌测定法测量试件切割面的表面粗糙度值,分析三维表面形貌图。结果表明:红橡木磨料射流的试验影响因素排序为CADB;竹地板磨料射流的试验影响因素排序为BCAD。红橡木和竹地板优化工艺参数为:进给速度为250 mm/s,磨料流速为35 kg/h,靶距3 mm,切割压力为310 MPa。在此加工工艺条件下切割材料表面粗糙度相对较小,加工所得材料品质较好。     

马来西亚轻轨三号线构架加工工艺优化

针对马来西亚轻轨三号线构架结构复杂、加工工艺要求高、加工产品质量要求高等难点，提出了马来西亚轻轨三号线构架整体加工工艺方案，并通过对实际的构架产品进行加工工艺验证，选择合理的工具、走刀路径及切削参数，保证构架加工的质量与生产效率。     

实木家具异形零部件成组分类与加工方法

为解决实木家具异形零部件加工难和效率低的问题,利用成组技术对异形零部件进行分类优化试验。选取96件橱柜、床、椅和桌几等4类家具的7 950个零件,其中异形零部件1 518个,根据异形零部件在长度、宽度和高度方向的造型差异及3个方向曲线和曲面的情况,通过加工相似性原理对异形零部件进行长型、曲型、轴型、复杂型和板型等成组分类,4类家具的曲型异形零部件和复杂异形零部件占比较高,分别为31.19%,34.78%,20.25%,33.88%和29.36%,28.26%,32.91%,37.19%;对分类零部件采用LWH(length-width-height)分类编码方法制定异形零部件的编码规则,形成零部件加工过程的物件流转信息代码;依据异形零部件形状分类优化结果,对加工方法、加工设备配置及工艺路线制定进行统一和优化后,整体生产效率提高了约25%,可见合理的成组分类与规范的加工方法有助于提高生产效率,设备负载率和生产线负荷率得到有效提升。本研究不仅为实木家具企业零部件加工提供了参考,同时也为生产线平衡优化、物件流信息流转提供了理论依据。     

百年孚尔默的生存之道——访德国VOLLMER集团CEO Stefan Brand博士

孚尔默成立于在1909年,最早经营用于锯齿刀片修整的磨齿机,目前产品包含应用于木工加工行业和金属加工行业锯片和工具的磨削和电火花机器。在该集团从单一的木材加工进入到金属加工业的发展历程中,逐步发展了刃磨、测量等业务,并在电火花和刃磨技术、激光加工等新型技术的导入上不遗余力。     

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.     

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。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.