新型圆锯片的研究

新型圆锯片的研究,旨在结合我国国情,不改变机床结构,不影响加工工艺和生产率的基础上,兼得降低锯路宽度、取消适张度处理工序、降低噪声的综合效果。一、新型圆锯片的结构新型圆锯片典型结构如图所示。在平圆锯片中部至孔径处切成辐条状,辐条端部呈扇形斜面。锯片安装夹盘制成具有径向隔板的滑槽状结构,以与锯片平面配合并传递扭矩。     

径向槽对硬质合金圆锯片"啸声"影响的研究

"啸声"是木工硬质合金圆锯片空转的主要噪声源,是一种自激振动噪声.本文主要研究径向槽对硬质合金圆锯片噪声的影响.研究结果表明,采用金属铜填塞径向槽底部圆孔技术,可以消除硬质合金圆锯片在整个测试转速范围的"啸声".而其他两种普通径向槽的圆锯片只能在较高转速下消除"啸声".此外,径向槽底部塞有金属铜圆锯片的空气动力性噪声比未塞有金属铜的圆锯片略低2～3 dB(A).     

铜对圆锯片热应力的影响与研究

通过锯切木材试验,分别对锯身槽上嵌铜和不嵌铜设计的同条件下木工圆锯片,进行定点温度、横向摆动量和噪声参数的测量;并结合有限元热应力场分布与计算,以及铜材理化试验分析等手段,得出其嵌铜锯片消除热应力性能好,振声性能较高,锯片使用寿命延长等结论,并提出减振降噪的措施与建议,为优化圆锯片的设计工作提供参考依据。     

木材低切削量锯切中圆锯片组在线冷却系统的研制

在圆锯片组锯切过程中，高速旋转的锯片与工件发生摩擦会产生大量的切削热。当圆锯片温度过高时，其振动急剧增加，变形增大，严重影响加工精度和出材率，而且存在安全隐患，为此设计了木材锯切冷却介质制冷雾化在线冷却系统。介绍了该系统的结构、工作原理、主要技术参数及系统设计。     

热控圆锯片适张度的理论探讨

目前,热控圆锯片适张度新技术在国内已开始应用,如黑龙江省方正林业局已在83年进行了远红外热控圆锯片适张度的应用技术鉴定。但有关这方面的理论尚在探讨中。圆锯片热控适张度的形成是由于在圆锯片中心的适当区域接受热源幅射的热能,并不断向边缘传导及向空间散发,形成锯片中心温度高而边缘温度低的温差。由于锯片的热膨胀受边缘的限制不能按其平面伸展而成碟形,碟形底面与边缘的高差即为圆锯片的适张度。     

木材加工超薄圆锯片基体结构对其稳定性的影响

木材加工超薄圆锯片的稳定性是影响锯切质量的重要因素之一,圆锯片的稳定性会随着锯身厚度的减小而降低。在切削木材过程中产生大量切削热会使锯身发生热形变,进而导致锯片稳定性降低。提高圆锯片切削稳定性传统的方法主要在生产工艺上通过对锯身施加预应力,抵消切削热对锯身形变的影响。本文通过改变锯身的基体结构,对不同基体材料的木工圆锯片进行基体几何处理,使其能够在切削木材过程中抵消热应力,从而提高切削稳定性。     

一种全新的圆锯片适张检测设备

圆锯片的适张与检测是制锯与修锯中必不可少的一道关键工序，对保证锯片稳定运转、提 高锯切精度和刀具耐用度十分重要。目前我国的相关企业，大多数还采用手工锤打适张和目 测锯片变形的“光隙法”，检测锯片的适张程度，这已远远不能适应现代工业的要求。为改 变这种落后状况，赶超世界技术发展的潮流，北京林业大学一课题组经多年努力，已成功研 制开发出一种全新的圆锯片适张状态现代计算机检测技术与设备。该技术与设备吸收了欧美 发达国家的最新相关成果，结合课题组开发的专利技术、专用软件和配套设备，可在工业环 境下对锯片状态的…     

特种硬质合金刨锯片

山西省太行锯条厂研制成功一种特种硬质合金刨锯片.它通过改变现有硬质合金圆锯片的结构,可提高切割寿命和切削精度,扩大了使用范围;它的特征在于硬质合金创锯片的锯体上冲出刨刀槽.在     

制约圆锯片极限转速的几个因素( 英文)

文章在分析讨论了影响圆锯片极限转速的一些重要因素后认为 ,包括锯片材料、结构、尺寸、内应力影响的最低共振临界转速是制约锯片极限转速的重要因素 .考虑到诸多影响因素后 ,文章建议圆锯片的最高极限转速以不超过该锯片未适张时的最低临界转速的 50 %～ 6 0 %较为适宜     

木工圆锯片的适张度及其控制

阐述了木工圆锯片适张度对其产品切割质量的影响，介绍了对锯片进行适张度处理的方法。     

Analysis of roll tensioning and its influence on circular saw stability

Summary In a typical sawmill, about 12% of the wood which is cut is reduced to sawdust. Further material is lost during subsequent planing. A substantial part of this large loss of a costly natural resource can be saved by the use of thin, stable sawblades, but only if proper saw tensioning conditions are developed. The thickness of a stable sawblade can be minimized through optimal tensioning, an increasingly urgent objective because of sharply rising raw material costs. A theoretical model is presented which accurately describes the development of residual stresses in a roll tensioned circular sawblade and the resulting changes in saw critical speed. This model is essential for the reliable prediction of optimal tensioning conditions for any given saw operating state, and for the development of automated control of the tensioning process. An example is presented of an optimally tensioned circular sawblade for which a 40% thickness reduction is achieved compared with an equivalent untensioned sawblade with the same critical speed.Paper awarded First Place Wood Award Price, Forest Products Research Society, June 1981     

圆环分区直齿热磨机磨片的温度场和热变形分析

基于摩擦学理论和传热学,利用ANSYS建立圆环分区直齿热磨机磨片的稳态温度场和热变形的三维热分析有限元模型,分析该磨片处于热平衡状态下的温升和热变形.结果表明,热变形对磨片之间间隙有一定影响.     

Internal decay assessment in standing beech trees using ultrasonic velocity measurement

Ultrasonic wave timing inspection was used to detect the internal decay in standing Iranian beech trees (Fagus orientalis). To evaluate the influence of internal decay on ultrasonic velocity, healthy round sections of freshly cut fallen beech trees were selected. Holes [as heart or internal decay indicator and with different shapes (circular and slot) and locations] were manually created and progressively enlarged in the wood section disks, and ultrasonic wave velocity was measured by using a commercial ultrasonic tester (Sylvatest Duo). The results showed that ultrasonic wave velocity linearly and significantly decreased by increasing hole dimensions, and location of holes had no influence on the extent and trend of velocity decrease. Although slots covered a small volume fraction of disks, they had a greater effect on ultrasonic velocities reduction as compared with circular holes.     

美洲黑杨×青杨F2代基本材性性状遗传变异研究

利用美洲黑杨×青杨杂交三代谱系探索了木材密度、纤维长、纤维宽、纤维长宽比和微纤丝角等性状的遗传变异规律.结果表明基本密度与纤维长受主基因的控制,表现为"质量- 数量性状",其杂种优势明显且在F     

Some possibilities for reducing circular saw idling noise

The sound pressure level of differently designed circular saw blades were investigated during idling. Nine blade samples were used: three differently designed blade bodies (without slots, with four radial slots, and with four slots with copper cork), each with three diameters (260,280, and 300 mm). The sound pressure level was measured at different rotational frequencies ranging from 25 to 65 rps in increments of 1 rps. Rubber damping rings 80mm in diameter and 0.3 mm thick were placed between the saw blade and the collars, and the emitted noise was measured. Because of the whistling sound the blades without slots emitted high sound pressure levels. There were no significant changes when rubber damping rings were used. The use of rubber damping rings on the samples with radial slots eliminates the whistling noise. The saws with copper corks did not emit a whistling noise at all, and their aerodynamic noise was 2–3 dB (A) lower than the aerodynamic noise of the saws with radial slots. The relation between sound pressure emitted by the damped idling saw and peripheral velocity can be described by the power function with the exponent value between 4.8 and 5.2.Part of this report was presented at the 14th International Wood Machining Seminar, Epinal, France, September 1999     

Effects of temperature and sulfonation on shear deformation of spruce wood

Summary The effects of temperature and sulfonation on the deformation of spruce wood at conditions comparable to those during screw press impregnation prior to mechanical pulping were studied using a dynamic testing method. In addition to the physical properties of wood, shear fracture surfaces obtained at different deformation temperatures and at different sulfonation levels were studied using scanning electron microscopy (SEM).The results showed that the failure energy of wood decreased gradually with increased deformation temperature in the tested range of 20–95 °C, due to thermal softening of the material. In addition to thermal treatment, the failure energy could also be reduced by sulfite treatment of the wood before deformation, and decreased with increasing sulfonation degree.The SEM analysis showed that increasing the deformation temperature causes the fracture plane to travel around the fiber walls instead of through them, thus exposing a smoother wood surface with less fiber damage. At a given deformation temperature, particularly at the lower temperatures, sulfonation improves fiber separation.Financial support from the Swedish National Board for Industrial and Technical Development (NUTEK) is gratefully acknowledged     

城市景观红竹林立竹冠形结构特征

对景观红竹林2007-2009年立竹的胸径、枝夹角、枝分角、冠长、冠幅、枝盘数进行了调查分析。结果表明:立竹冠长、冠幅、枝盘数与立竹胸径分别呈3次、2次多项式和线性关系;当立竹密度45023株/hm2以下时,不同年龄立竹不同竹冠部位的枝夹角无显著差异,立竹密度为26713株/hm2时,立竹不同竹冠部位的枝分角差异极显著;试验林立竹密度范围内,立竹密度对枝夹角、相对竹冠长无显著影响,对枝分角、相对冠幅、相对枝盘数有一定的影响。随着立竹密度的增大,竹冠上部枝分角显著下降,竹冠中部、下部枝分角呈先升后降趋势,相对冠幅、相对枝盘数呈下降趋势。当立竹密度为60030株/hm2时,枝分角、相对冠幅、相对枝盘数显著下降,对竹林的更新生长已产生不利影响。     

山丘区钉螺大小特征与水分依赖性

本文研究了山丘区钉螺壳体长宽鲜重体积,以及疫区壳体长宽与区域降水温度的关系。仁寿县钉螺鲜重0.0162 g(浮动在0.0065 g～0.0219 g之间),体积4.5894 mm3(3.12 mm3～5.6 mm3),长度5.156 mm(3.6 mm～6mm),宽度为2.668 mm(2.2 mm～3 mm)。分析表明,长度5 mm～6 mm为主体,宽度2.5 mm～3 mm为主体,钉螺宽度随着长度作缓慢而显著的增加;鲜重与群体的长度、宽度、体积无关。潮湿稻田生境钉螺长度明显最大,而干燥与湿润生境中次之,但宽度、体积、鲜重差异不明。疫区不同区域钉螺长度、宽度与降水量显著相关,而与温度无关,温度降水量比值与钉螺长度、宽度关系密切,表明钉螺大小有水分依赖性。在疫区内,可能水温匹配性共同塑造了钉螺的大小。     

山西翅果油天然群体果实多样性研究

翅果油(Elaeagnus mollis Diels.)为胡颓子科胡颓子属,又名柴禾、毛折子、贼绿柴、仄棱蛋,是我国特有的木本油料树种.翅果油种子出油率为32.5％,其中,油酸40.36％,亚油酸50.38％[1-4];经初步测量,成年单株每年可产果40 kg;目前,测定的Ve含量高达15.581 mg·g-1,并且还富含其它活性物质,如Vc、甾醇等,具有较高的经济价值[5-6].翅果油根系发达,具固氮能力,在生长条件恶劣的黄土高原地区能够正常生长结实,耐旱、耐瘠薄能力较强,具有重要的生态价值[7-8].