微量零锯料角锯齿木材锯切特性与机理研究

发布时间：2018-04-24 22:09

本文选题：木材锯切 + 锯料角　；参考：《中国林业科学研究院》2017年博士论文

【摘要】：木材锯切为闭式切削,锯齿以三条刃口切削木材(一条主刃,两条侧刃),锯齿一次切削后完成三个切削面——锯路底和两侧锯路壁。但目前关于木材切削力和表面质量的研究大都集中在对锯齿主刃参数的优化方面,忽视了侧刃对切削力和表面加工质量的影响,且随着近年来,木材价格的不断提高,木工锯片的厚度也越来越小,侧刃在锯切过程中的作用也越来越引起人们的关注。本文重点围绕木材闭式锯切过程中锯齿侧刃产生的切削力和锯路壁形成机理展开研究,首次提出了微量零锯料角锯齿锯切的概念,研究了不同锯料角、不同切削厚度、不同含水率、不同切削速度和不同切削方向等切削条件下,锯齿侧刃产生的切向力和法向力的变化规律及影响因素;利用响应面分析方法,建立出微量零锯料角锯齿切削力多元响应面回归模型;并设计制造出9种不同锯齿齿形圆锯片,在不同切削条件下进行了锯切表面粗糙度试验,分析出锯齿侧刃参数对锯切表面粗糙度的影响。通过以上理论分析和试验研究,最终确定出最佳的微量零锯料角锯齿的齿形参数。得出以下主要结论:(1)通过理论分析得出锯齿受力应包括锯齿主刃受到来自木材的抗力和摩擦力,侧刃受到的来自锯路壁的摩擦力和抵抗力以及齿室内锯屑与锯路壁之间产生的摩擦力三部分。单锯齿切削时,可将锯齿侧刃受力分为侧刃切向力和侧刃法向力,其中,侧刃受到的来自锯路壁的摩擦力和抵抗力主要以侧刃切向力为主。(2)推导出了圆锯锯切时锯痕的理论深度公S_n式:并提出了微量零锯料角锯齿概念,其侧刃是由零锯料角段l1和非零锯料角段l2组成,其中零锯料角段承担切削,零锯料角段的长度理论上略大于每齿进给量,且越接近每齿进给量越理想。(3)锯齿侧刃产生的力主要以侧刃切向力为主,本论文中采用锯齿宽度2.6mm的硬质合金锯片单齿分别对樟子松和水曲柳两种木材进行纵向、横向和端向切削,当在锯料角为0°~3°,切削厚度为0.08 mm～0.16mm,含水率为5%～19%和切削速度为5m/min～15m/min的情况下,侧刃产生的侧刃切向力占总切削力的4.6%～20.2%,而侧刃法向力由于受到刀具和工件振动等因素的影响其变化没有明显规律。(4)随着锯料角由1°增加到3°,侧刃切向力呈减小趋势,切削水曲柳(0.16mm)时,由7.176N降低到2.900N;切削樟子松(0.16mm)时,由5.733N降低到2.959N。随着切削厚度的增加,侧刃切向力增大。(5)切削不同树种时,切削速度变化其对侧刃切向力的影响并不相同,切削水曲柳时(λ=3°),其侧刃切向力由1.989N增加到3.455N,切削樟子松时(λ=3°),其侧刃切向力先由0.105N增加到2.754N,而后降低到1.457N。这受到木材的抗拉强度和切削方向的影响,当进行纵向切削时,当超前裂隙的扩展速度大于切削速度时,其侧刃切向力呈减小趋势。(6)切削不同树种时,当含水率由5%增加到19%,其对侧刃切向力的影响并不相同,造成这一现象的主要原因可能是由于含水率变化会引起木材抗拉强度和韧性的交互作用而产生的。(7)在相同的锯料角条件下,横向切削时,侧刃切向力最大;纵向切削时,侧刃切向力次之;端向切削时,侧刃切向力最小。(8)当切削过程中综合考虑切削厚度、含水率、切削速度和锯料角等参数对切削力的影响时,其与切削力的关系并不是简单的线性关系,而是呈二次多项式关系,其切削力回归方程可归结为:Fy=A-Bλ+Ch-DMC+EU+Fh MC+Gλ~2+Hh~2+IMC~2+JU~2,其中:A、B、C、D、E、F、G、H、I和J均为试验确定的系数。(9)当零锯料角段由0mm增加到0.5mm时,表面粗糙度值显著下降,切削水曲柳λ=1.5°时,表面粗糙度值分别由30.1μm降低到23.8μm,λ=3°时由33.3μm降低到26.2μm。但当零锯料角段大于0.5mm的情况下,其表面粗糙度随零锯料角段增加的影响不明显。
[Abstract]:Wood sawing is closed cutting, and the sawtooth cutting wood (one main blade, two side blade) at three edges, and after cutting the sawtooth after one cutting to finish three cutting surfaces - sawing road bottom and side sawing wall. However, most of the research about the cutting force and surface quality of wood focuses on the optimization of the parameters of the sawtooth main edge, ignoring the cutting force of the side blade. With the influence of the surface processing quality, and with the continuous improvement of the timber price in recent years, the thickness of the woodworking saw blade is becoming smaller and smaller. The role of the side blade in the sawing process has attracted more and more attention. This paper focuses on the cutting force produced by the sawtooth side blade and the formation mechanism of the saw wall during the closed cutting process of wood. The concept of trace saw tooth cutting with zero saw angle was put forward, and the change law of tangential force and normal force produced by the sawtooth side blade was studied under different cutting angle, different cutting thickness, different water content, different cutting speed and different cutting direction, and the trace angle of zero saw was established by the response surface analysis method. The sawtooth cutting force multiple response surface regression model, and 9 different sawtooth profile circular saw blades were designed and manufactured. The sawing surface roughness test was carried out under different cutting conditions, and the effect of the parameters of the sawtooth side blade on the sawing surface roughness was analyzed. The best trace zero saw angle was determined by the above theoretical analysis and experimental research. The following main conclusions are obtained: (1) through theoretical analysis, the force of the sawtooth should include the resistance and friction of the sawtooth main blade from the wood, the friction and resistance of the side blade from the saw wall and the friction force between the sawdust and the saw wall. The force of side blade is divided into side blade tangential force and lateral blade normal force, of which, the friction force and resistance of side blade from the saw wall are mainly by side blade tangential force. (2) the theoretical depth common S_n formula of saw saw when saw saw cutting was derived, and a trace zero saw angular saw tooth was proposed, its side blade was composed of zero saw angle segment L1 and non zero saw angle. Section L2 consists of a zero sawing angle section for cutting, and the length of the zero saw angle section is slightly larger than the feed per tooth, and the closer the feed is to each tooth. (3) the force of the sawtooth side blade is mainly by the side blade tangential force. In this paper, two kinds of single teeth of the hard alloy saw blade with the sawtooth width are used respectively to the Pinus sylvestris and the Fraxinus mandshurica. In the longitudinal, transverse and end cutting of wood, when the sawing angle is 0 ~3 degrees, the cutting thickness is 0.08 mm to 0.16mm, the water content is 5% ~ 19% and the cutting speed is 5m/min to 15m/min, the side blade tangential force produced by the side blade is 4.6% to 20.2% of the total cutting force, and the lateral blade force is influenced by the factors such as the tool and the workpiece vibration. There is no obvious law in the change. (4) as the sawing angle increases from 1 to 3, the cutting force of the side blade decreases and the cutting water ash (0.16mm) decreases from 7.176N to 2.900N; when the cutting of Pinus sylvestris (0.16mm), from 5.733N to the increase of the thickness of the cutting, the cutting force increases with the thickness of the cutting. (5) the cutting speed changes its opposite side when cutting different species of tree species. The effect of cutting force is different. When cutting Manchurian ash ([lambda =3]), the tangential force of the side edge is increased from 1.989N to 3.455N, and when cutting the Pinus sylvestris ([lambda] =3), the side blade tangential force is increased from 0.105N to 2.754N, and then to 1.457N., which is influenced by the tensile strength and cutting direction of the wood, when longitudinal cutting is carried out, when the forward fissures are made. When the expansion speed is greater than the cutting speed, the lateral blade tangential force decreases. (6) when the water content is increased from 5% to 19%, the effect of the cutting force on the lateral blade tangential force is different. The main reason for this phenomenon may be that the change of water content can cause the interaction of tensile strength and toughness of wood. (7) Under the same sawing angle condition, the lateral cutting force is maximum in lateral cutting, while the side blade is the second cutting force in the longitudinal cutting and the side cutting force is the least. (8) when the cutting thickness, water content, cutting speed and saw angle are taken into consideration in the cutting process, the relationship between the cutting force and the cutting force is not simple. The linear relation is two times polynomial relation, and the regression equation of cutting force can be summed up as follows: Fy=A-B lambda +Ch-DMC+EU+Fh MC+G lambda ~2+Hh~2+IMC~2+JU~2, in which A, B, C, D, E, F, G, H, etc. are all determined by the test. (9) when the angle segment of the zero saw material is increased, the surface roughness value drops significantly, and the surface roughness is rough. The degree of degree is reduced from 30.1 to 23.8 m, respectively, and when the angle section of the zero saw is greater than 0.5mm, when the angle segment of the zero saw is greater than 0.5mm, the effect of the increase of the surface roughness on the angle segment of the zero saw is not obvious.

【学位授予单位】：中国林业科学研究院
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TS652

【参考文献】