15种阔叶树材中切削厚度、刀具前角和木材含水率对切削阻力的影响

１５种阔叶树材切削厚度、刀具前角和木材含水率对切削阻力的影响进行了研究。针叶树材不同树种中此三因素对切削阻力影响的规律，在阔叶树材中有相似表现。在气干到充分吸湿阶段中，含水率对切削阻力影响的趋势在针叶材和阔叶材中有所不同。     

15种叶树材中切削厚度,刀具前角和木材含水率对切削阻力的影响

１５种阔叶树材切削厚度、刀具前角和木材含水率对切削阻力的影响进行了研究。针叶树材不同树种中此三因素对切削阻力影响的规律，在阔叶树材中相似表现。在气干到充分吸湿阶段中，含水率对切削力影响的趋势在针叶材和阔叶材中有所不同。     

11种针叶树材的切削厚度、刀具前角和木材含水率对切削阻力影响的研究

对11种针叶树材在0-90、90-0和90-90三个切削方向的高速直角自由切削的试验研究表明:1)切削厚度、刀具前角和木材含水率对主切削力影响的基本趋势,各树种基本一致,但定量考察有一定的差异;2)三因素影响的阻力比值R_t、R_a和R_w在不同树种中变异不大;3)三因素对切削阻力的影响存在一定的交互作用,在不同切削方向,情况有所不同。     

11种针叶树木材密度与切削阻力关系的研究

对我国11种针叶树木材密度与切削阻力关系研究的主要结果是:1)11个树种内,木材密度与切削阻力关系的相关性,90-90方向切削普遍明显高于0-90和90-0方向,其回归系数有随树种平均密度增大而增大的趋势;2)种间密度与切削阻力关系的相关性性较种内者高,其回归系数与各种内关系的回归系数的平均值接近;3)切削厚度、刀具前角和木材含水率对种间密度阻力关系的影响表现统一的趋势,即各树种的平均切削阻力越大,密度与切削阻力关系的回归系数越大;4)试验中发现了若干表现密度与切削阻力关系分散性的某些特点的现象。     

15种阔叶树木材密度与切削阻力关系的研究

继１１种针叶树材之后，对１５种阔叶树木材密度与切削阻力的关系进行了研究。针叶树材试验中发现的主要规律在此得到进一步证实。     

红松水曲柳木材密度与切削阻力关系的研究

本文继前一报告之后,对红松、水曲柳木材密度与切削阻力的关系做了进一步的研究。主要的结果是:(1)木材密度与切削阻力的关系因树种、切削方向、切削厚度、刀具前角和木材含水率之不同而有差异;(2)切削厚度、刀具前角和木材含水率对密度与切削阻力关系的影响有统一的趋势,而且此趋势可用简单的线性关系表述;(3)木材中密度以外的影响切削阻力因素的分布状况,从株内较大范围看,半径和树高方向不同部位间均未表现出显著差异。     

壳聚糖前处理提高木材表面染色效果的研究

本文采用壳聚糖对木材表面进行前处理后，然后按不同树种，同一染料和同一树种，不同染料两种方式进行染色试验。结果表明：不同树种壳聚糖处理与未处理材的染色效果相比，处理材染色均一，没有色斑，颜色浓深，木材纹理清晰，当采用酸性红Ｇ染色，处理材明度减小，色饱和度增加，色差和色相差变化均很大；同一树种的处理材用不同染料染色，效果不同，亮色系染料染色效果较暗色系染料好。     

木材切削阻力测定中刀具锋利程度的控制

本文从木材试样内切削阻力的变异和不同条件下代表一定刀具锋利程度差异的切削祖力差异的变异两个方面,论证了在直角自由切削主切削测定中,通过对木材试样的试切削进行刀具锋利度控制的有效性,并为此种方法的合理运用提供了依据。     

热固性树脂真空加压浸注工艺条件的研究

以西南桦和械木为研究对象，探索不同种类的热固性树脂和不同浸注条件与树脂浸入量和改性材尺寸稳定性的关系。研究结果表明，不同树脂，甚至同一树脂对不同树种的木材具有不同的浸注性，其浸入量随加压浸注时间的延长而增加；木材心边材对树脂的接收能力有所不同；木材性能的改善程度因树种和树脂浸入量而异。     

木材横纹压缩过程中径向,弦向加载差异性分析

利用我国东北地区的11个树种为试材，采用先进的测试及计算手段，揭示木材横纹压缩大变形的全过程，比较分析了不同测试条件、不同树种的试材在径向、弦向加载条件下的差异性．     

沙柳材端向切削特性的研究

为了明确影响灌木材端向切削力的主要因素,改进削片机性能,提高灌木材削片质量,笔者研究了不同刀具前角、切削厚度和不同含水率对沙柳(Salix psammophila)材端向切削力的影响。结果表明刀具前角对法向力的影响较小,对主切削力影响较大;切削厚度对主切削力的影响较为明显,随切削厚度的增加,主切削力明显增加;沙柳材含水率15％以下主切削力随含水率增加略有增大,之后逐渐减小,其中含水率在30％-70％之间时,切削力变化不大。     

Towards a model predicting cutting forces and surface quality in routing layered boards

The general aim of work reported here was to assist designers and operators of routers and similar tools for cutting wood-composite boards, by providing a model predicting cutting force components from readily available material properties. This initial study explored, for edge cutting, the variation within a single medium density fibre board across the thickness and in various cutting directions in the plane of the board. Material properties of interest were specific gravity and friction coefficient. In slow linear cutting on a modified milling machine, carbide router inserts cut the edges of layers cut from a medium density fibre board. Specific gravity and coefficient of sliding friction were measured for each layer. Cuts were also made on full-thickness edges in various directions in the plane of the board. Chip thickness was varied from 0.025 to 0.8 mm. Parallel and normal force data and digital video images of chip formation were stored for analysis. Specific gravity increased as the fourth power of the distance from the central plane to the surface. Friction coefficient values, estimated both from cutting forces and from rubbing forces during return, varied about a value of 0.23, with no significant difference between layers. The values for cutting force per mm width of cut increased progressively from the central plane to the surface, in a logarithmic relation with specific gravity. The cutting forces did not vary with cutting direction in the plane of the board. For a sharp edge with 32° rake angle cutting at chip thickness values above 0.1 mm, the normal force component was negative, indicating reduced feed force and improved surface quality. With dulling, the threshold value of chip thickness for this increased. It is concluded that elaboration of this approach would generate relationships suitable for incorporating in a useful general model. However, it may be found that weight per unit area of board will suffice as a proxy for cutting resistance in modelling the cutting of full-thickness edges. Received 10 June 1999     

刀具角度对杨木刨片和刨花板性能的影响

以不同角度刀具切制杨木刨片,并制成大片刨花板,对刨片的流变和强度性能及刨花板性能进行了测定和研究。主要结果是:(1)采用较大前角刀具所切出的刨片的流变和强度性能较好,刨花板平面抗拉强度有显著提高,抗弯强度亦有改善;(2)微斜面可在不显著影响刨片和刨花板性能的条件下增强刀刃,为进一步采用更大的前角提供了可能性。     

Cutting force variability as a consequence of exchangeable cleavage fracture and compressive breakdown of wood tissue

In the present study, the conditions of chip propagation or fracture in orthogonal oblique cutting of beech wood (Fagus silvatica) in the 90°–0° direction for a type-I chip has been investigated. The force required for orthogonal wood cutting is pronouncedly variable, which is the consequence of exchangeable different ways of material breakdown. The chip formation process is discontinuous because of interrupted splitting of the material in front of the cutting tool. A 10-mm-thick specimen was cut at a rake angle of 31° and 42° with chip thicknesses ranging from 0.1 to 0.3?mm. The chip segment length increased with the chip thickness. A chip of varying length and thickness was modelled using the finite element method. For each case, the bending or compressive stress in the chip and the stress intensity factor at the crack tip was calculated. The segment length of the chip can be calculated by taking into account the condition that a crack propagates when the stress intensity factor K _I at the crack tip equals the critical stress intensity factor K _IC, and the bending or compressive stress σ _x in the chip is smaller than the strength σ _u . Good agreement between the calculated and the measured values was observed. The chip segment length can change considerably already with small changes in the bending strength and critical stress intensity factor. This large sensitivity is also confirmed by the fluctuation of the measured chip segment lengths by as much as 400%.     

A global rheological model of wood cantilever as applied to wood drying

In the process of wood drying inevitable stresses are induced. This often leads to checking and undesired deformations that may greatly affect the quality of the dried product. The purpose of this study was to propose a new rheological model representation capable to predict the evolution of stresses and deformations in wood cantilever as applied to wood drying. The rheological model considers wood shrinkage, instantaneous stress–strain relationships, time induced creep, and mechano-sorptive creep. The constitutive law is based on an elasto–viscoplastic model that takes into account the moisture content gradient in wood, the effect of external load, and a threshold viscoplastic (permanent) strain which is dependent on stress level and time. The model was implemented into a numerical program that computes stresses and strains of wood cantilever under constant load for various moisture content conditions. The results indicate that linear and nonlinear creep behavior of wood cantilever under various load levels can be simulated using only one Kelvin element model in combination with a threshold-type viscoplastic element. The proposed rheological model was first developed for the identification of model parameters from cantilever creep tests, but it can be easily used to simulate drying stresses of a piece of wood subjected to no external load. It can therefore predict the stress reversal phenomenon, residual stresses and maximum stress through thickness during a typical drying process.