单板旋切生产线分级码垛装置的设计

为解决单板旋切生产线中人工分级码垛工作量大、效率低下的问题,设计一种自动分级、码垛的一体化装置。通过分析相邻单板传送特点,设计单板图像全覆盖的采集方法,依据图像中单板覆盖传送带面积大小确定分级依据;结合动作时间确定机械响应距离,以平面四杆机构作为执行端来实现生产线分级、码垛一体化作业,根据旋切原木产生单板的规律确定分级架全部动作次序,Adams运动学仿真结果验证了四杆机构的可行性。     

竹材旋切的数学模型建立与理论分析

【目的】为加工出等厚连续的整张竹单板,减小竹材无卡轴旋切机加工竹材选取的局限性,扩大旋切设备的应用范围,提高竹材旋切的整体出材率和成品率,提出一种以"对数螺旋线"为基础的新型旋切曲线数学模型,并计算竹单板的理论出材率,分析讨论所建立模型是否适用于无卡轴竹材旋切机的使用。【方法】对旋切机2种旋切曲线进行数学建模,利用Matlab软件对传统无卡轴旋切理论"阿基米德螺旋线"的数学模型及改进的旋切曲线数学模型(呈椭圆形的"对数螺旋线"旋切曲线)进行仿真分析,建立待加工竹材段的三维模型,结合Matlab仿真结果,对竹材旋切出材率公式进行推导。【结果】通过Matlab仿真结果可知,"阿基米德螺旋线"为圆形螺旋线,由于竹材横截面不规则且近似为椭圆形,壁薄,旋成圆形后,竹材壁厚加工余量小,圆形螺旋线旋切曲线并不完全适用于加工自然生长的竹材,存在加工竹单板易碎、形状不整等缺陷;改进后的"对数螺旋线"旋切曲线呈椭圆形,旋切曲线贴近竹材实际形状,可以保证相邻螺旋线距离误差精确度在许可范围内,模型更加适用于竹单板旋切。数学模型参数可以根据竹材内外径大小实时调整,缩小竹材选取局限性。对推导出的出材率数学模型进行分析,得出竹材的材率η与竹段长度L无关,但应注意长度、壁厚和尖削度的相互影响。【结论】改进后的旋切曲线数学模型以"对数螺旋线"为基础,在旋切竹材时单板厚度误差小,旋切效率更高,具有很高的可靠性和加工精度。在满足加工要求的前提下,为保证竹材出材率、旋切效率、旋切质量等具体要求,加工竹段长度L应在0.8～1 m,竹材壁厚大于10 mm,尖削度小于3～4 mm·m^-1。新的旋切模型的建立可提升竹材的整体利用率,拓宽加工范围,为竹材旋切设备设计提供基础理论,对无卡轴竹材旋切加工提出一个新的发展方向。     

单板的综合加工及物理分析

生产优质的单板首先要选择优质的原木,然后根据不同产品的要求,选择使用平切、有卡旋切或是无卡旋切的加工技术。由于原木在生长季节光照不均匀,同一根原木出现了木质软硬度不同的现象,称为阴阳面,原木阴阳面的有无或是轻重,在旋切单板的过程中都表现出了不同的物理特性。     

桤木旋切单板以及用于制造细木工板的工艺研究

通过设置不同的旋切厚度对不同树龄的桤木原木进行单板旋切试验,分析单板厚度和背面裂隙率,探讨桤木单板旋切的适应性和制造细木工板的工艺,并采用正交法优选最佳制造细木工板的热压工艺参数。结果表明:当杉木板芯厚度为12 mm、桤木单板厚度为2.8 mm时,热压温度为125℃、热压压力为1.3 MPa、热压时间为8 min、施胶量为220 g/m~2时,横向静曲强度最大。     

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。     

对国家标准《小径原木》的修订

小径原木是指长度在2～6m、径级在4～16m之间的森林采伐剩余物,或在营林中抚育间伐的幼龄树,又被称为小径木或小径材。近年来,随着木材资源紧缺形势的不断加剧,小径原木逐渐成为木材加工的主要原料,通过对小径原木的剖分、旋切、挤压等生产工艺,可分别制成重组木、单板层积材、单板条平行成材和层叠单板条成材等,它们具有良好的机械加工性能和结构稳定性,广泛应用到地板、家具、建筑等行业。小材大用,提高了小径原木的综合利用率和附加值,需求量亦不断增长。     

旋切线原木输送机金属探测装置的设计分析

为了防止原木中的金属夹杂物对单板旋切设备的损坏，对现有单板旋切生产线的原木输送机进行改造设计： 增加了金属探测装置，并与电涡流传感器检测装置联合作用，以提高检测灵敏度；增加了U 型槽及液压控制开合的 挡板，用于分离含金属杂物的原木, 保证旋切线安全生产。     

计算机模拟原木三维廓形

在单板旋切过程中，首先需要确定原木的回转中心，而能否精确地确定原木的回转中心，实现原木回转中心线与最大内接圆柱体的中心线相重合，又取决于计算机能否精确地模拟原木的三维廓形。本文介绍一种通过绘制原木透视投影图的方法来模拟原木的三维廓形。１数据采集 在原木长度方向上设置４个激光扫描器。原本每旋转１０°采集一次数据，原木回转一周，每个激光扫描器就可采集到原木横断面上的３６个点的数据。 激光扫描器采集数据的原理如图１所示。由圆的极坐标曲线方程可知： 由式（１）和（２）即可获得原本横断面上的型值点Ｘ．Ｙ的坐…     

单板旋切扭矩之测试

在单板旋切过程中，单板背面裂隙度是影响单板质量的最主要因子。裂隙的发生与单板在旋切过程中受到的应力密切相关。为了对单板旋切过程进行系统性的理论分析，优选出最佳工艺因子，提高单板质量，准确掌握单板旋切过程中的功率消耗，单板旋切作用力的分析和测定是至关重要的。单板旋切是一个正交的木材切削过程。由于木材的各向异性·测量单板旋切作用力比测量金属切削力更为复杂。但通过单板旋切过程分析可知，单板的旋切作用力可分为切向作用合力和径向作用合力两部分。而切向作用合力可通过单板旋切时的扭矩测试值经换算而求得。因此单…     

新型BXP1814/5型原木剥皮找圆机的设计与应用

介绍了原木剥皮找圆机的工作原理，其利用三辊自动定心、锯齿形辊齿强力带动原木转动，通过操纵手动阀可将有节疤及不规则的原木自动剥皮和找圆。使用该机可大量减少人工剥皮作业，提高加工效率，保证旋切单板质量，是旋切板厂的理想设备。     

无卡轴旋切机变速进给模型与恒线速旋切运动轨迹模型的研究

详细分析了无卡轴旋切机的工作原理,推导了旋切过程中刀刃进给速度与圆木直径的数学模型,同时得出旋切时间的近似计算式。从中可知,旋切过程中刀刃进给速度必须按一定规律变化才能保证旋切机正常工作。建立了旋切机恒线速旋切的运动轨迹模型,推导出旋切机恒线速旋切时间的精确计算式,并在此基础上提出了旋切时间简便的近似计算式。这些研究结果均可用于指导设计和进行实际生产。     

Yield and mechanical properties of veneer from Brachystegia nigerica

In an effort to find suitable wood from natural forest to meet the demand for veneer products, the yield and tensile strength of veneers produced from Brachystegia nigerica were investigated. Two trees of B. nigerica were separately selected from 10 different natural forest zones while two logs were obtained from each tree. The logs were debarked and steamed in a vat prior to rotary peeling and slicing for veneer production. The optimum steam temperature was determined by considering different temperatures: 50°C, 60°C, 70°C, 80°C and 90°C for 24 h. Thereafter, optimum steam time was determined at the optimum temperature by considering durations of 24, 48, 72 and 96 h. The average taper of 0.75 mm per 1.0 m length was recorded for B. nigerica, indicating that the logs were reasonably cylindrical; thereby its logs are good for the production of veneer. The yield ranged from 44% to 61% with an average of 52% of the log input. The tensile strength of the veneer was tested perpendicular to grain and both peeled and sliced veneers had the highest tensile strength between 70°C and 90°C, suggesting that softening of wood polymers, especially lignin, is between 70°C and 90°C. The optimum temperature and time for veneer production are 70°C and 48 h, respectively. Commercial production of veneer from B. nigerica is feasible based on the yield and mechanical properties of the obtained veneer, thereby encouraging the expansion of the scope ofits utilization.     

火炬松旋切及单板质量与木材性质关系的研究

鉴于对国产火炬松木材性质和胶合板制造技术研究甚少的现状，本试验检测了火炼松的木材密度、硬度及横纹抗弯性能，同时采用不同的旋切参数进行单板旋切试验。在试验的基础上研究了木材性质瑟旋切条件和单板质量的关系。结果表明：木材的密度、硬度和横纹抗弈性能与旋切条件和单板质量有着密切的关系；采用适宜的旋切条件，可以得到质量较好的单板，火炬松单板旋切是可行的。     

竹单板旋切工艺的初步探析

通过对竹材旋切机与旋切工艺的初步探讨，并分析其工艺特点，从而总结出竹材旋切工艺的有关技术要求和综合利用措施。     

Online control of wood peeling process: Acoustical and vibratory measurements of lathe checks frequency

In the course of most wood machining processes, operators are usually able to detect various problems simply by hearing the sound emitted by the process. This is especially true for wood peeling. Lathe checks formation has been identified as one of the typical situations that an experimented peeler can detect. Poplar and beech veneer samples have been produced on a laboratory microlathe, using working conditions deliberately favourable to checking. Forces, sound, and vibration levels were measured during the tests. The lathe check frequencies have been determined on both sound and vibration signals using a local Root Mean Square (RMS) averaging and a peak detection algorithm. This makes possible the evaluation of lathe checks distribution along the veneer length. The technique was validated by measuring the real veneer profile using a specific apparatus developed by IVALSA-CNR in Trento (Italy).     

Using acoustic wave velocity to select fibre-managed plantation Eucalyptus nitens logs for laminated veneer lumber products

The aims and objectives of this study were to investigate the potential to predict laminated veneer lumber (LVL) stiffness from wood properties measured on trees and logs, and determine variation in log, wood and veneer properties as a function of tree height and age. Log selections were made from trees in three stands that were planned for harvesting at 14, 20 and 21 years of age. Rotary peeled veneer recovery from the logs was on average 65%. After drying, Metriguard testing showed over 50% of the veneer had an estimated dynamic modulus of elasticity (MOE_dyn) above 12 GPa, with 20% above 14 GPa, and that veneer from the second log by tree height had higher MOE_dyn values. In visual assessment to the AS/NZS 2269.0:2012 Standard, no veneer could be utilised in a panels face or subface positions and the older-age stand provided almost four times the volume of usable veneer. Standing-tree acoustic wave velocity (AWV) explained a moderate amount of variance in log MOE_dyn and Pearson correlation coefficients between the (Metriguard) veneer MOE_dyn, log AWV, log MOE_dyn and disc basic density were significant, positive and strong, with log AWV explaining most of the observed variance in log stiffness. A moderately strong and positive linear regression existed between log AWV and veneer MOE_dyn, supporting the use of log AWV tools for the ranking of stiffness in fibre-grown plantation E. nitens logs. Mechanical strength testing of LVL studs extracted from panels manufactured from the trial’s veneer indicated they equalled, and for some tested parameters exceeded, the characteristic design strength values previously published by commercial LVL manufacturers for equivalent size pine products.     

出口地板用杨木单板生产技术关键

根据出口地板用杨木单板的质量要求 ,对单板生产过程中的工艺参数及设备进行了调整 ,对旋切和干燥等关键工艺进行了详尽的阐述     

桉木单板出材率与价值影响因子研究

以4个品种的10个6年生桉树无性系为材料,进行立木生长性状调查、原木外观形质检测和单板质量等级划分,运用方差分析、相关分析及多元回归分析,系统地对单板出材率与价值影响因子进行研究。结果表明：4个品种的无性系单板材以尾巨桉无性系价值最高。无性系间立木生长性状存在极显著差异,其中树皮厚度差异最大。单板外观缺陷中的节子,尤其死节（孔洞）、裂缝是降低单板质量等级的主要因子。材积、弯曲度和尖削度是影响单板出材率与价值的主要因子。建立的单板出材率、单段原木价值和单位材积价值预测模型,对指导生产经营具有一定的意义。     

世界原木定心技术现状及发展趋势

原木定心技术在木材加工生产中广泛应用。精确定心,对提高木材利用率及经济效益是十分重要的。在分析现有定心技术的基础上,综合世界森林资源短缺及科学技术进步情况,提出原木定心技术向采用计算机扫描控制、提高精度、效益和效率方面发展是必然趋势。