圆锯片最佳辊压适张度处理位置的分析

利用非线性理论和矩阵摄动理论，研究了离心力场，切削温度场及辊压适张度位置对圆锯片动态特性和临界转速的影响，对离心力场，切削温度场共同作用下锯片最佳辊压适张处理位置进行了计算分析，还分析了锯夹半径对最佳辊压位置的影响。     

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。     

纵剖优选锯主轴调整系统结构的设计与仿真分析

针对传统板材锯切设备大多数处于半自动化状态,且存在加工精度低、出材率低、安全性差等缺点,笔者提出一种用于毛边板材裁边的纵剖优选锯设备的主轴调整系统。通过对毛边板材的裁边工艺进行分析,利用三维软件对纵剖优选锯主轴调整系统结构进行实体建模,确定了纵剖优选锯主轴调整系统的总体结构。对主轴组件上的锯片切削力和切削功率进行详细的设计计算,完成了主轴调整系统的主轴组件、锯片调整组件等结构的设计研究。根据锯片滑台最大许用应力和最大变形量对其进行有限元静力学仿真分析,通过仿真结果校核得出的锯片滑台满足设计要求。设计的纵剖优选锯主轴调整系统结构具有适用于产品多规格、高出材率、高自动化和实用性强的特点。     

圆锯片适张状态检测方法的研究(英文)

文章论述了一种圆锯片适张状态的检测方法及实现的系统 .该方法采用锯片适张前后固有频率的变化幅度 ,锯片单点加载情况下一定半径圆周上的横向变形量和端面圆跳动三个特征参量 ,表述一个锯片的适张程度、适张均匀性和平整性 .应用计算机控制的检测系统 ,经过对大量不同规格木工锯片和大型金刚石锯片的检测 ,结果表明该方法是切实可行的     

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     

The light-gap technique as a tool for measuring residual stresses in bandsaw blades

The relationship between residual stress distribution induced in bandsaw blades by cold rolling during tensioning and the transverse deflected shape obtained when the tensioned blade is bent over a given radius is studied. It is shown that the light-gap technique is not a reliable estimator of residual stresses since, while two transverse deflected shapes may be close to each other, the corresponding stress distributions may be far apart. The technique may be improved, within limits, by decreasing the tolerance with which a desired transverse deflected shape is approached during the tensioning process. A method for computing this tolerance is given.     

锯链传动链片的有限元分析

用有限元法对锯链的传动链片进行了应力分析，结果表明：危险剖面上的应力分布是不均匀的，在运转中传动链片所受的应力为变应力，按传统的方法仅计算静强度是不够的，要提高锯链的使用寿命，必须提高锯链零件的疲劳强度。     

反光式突起路标功能失效ANASYS分析

根据目前道路上安装的反光式突起路标存在破坏率高、反光功能失效快等问题,在调查数据基础上,分析得出反光式突起路标的主要破坏形式为脱落、压碎、凹陷、反光性能衰减等,破坏主要原因有基体材料抗压强度不够、机体与路面粘结不牢固等。在此基础上,运用ANSYS软件,建立有限元分析模型,将影响因素分为静荷载与动荷载两种情况分别加载到有限元分析模型上进行力学分析,模拟得出突起路标的主要应力集中点在突起路标表面四个边缘区域与钉脚与基座衔接段。将ANSYS分析数据导入Fe-Safe软件,模拟得出突起路标在荷载作用150482次后发生破坏,疲劳寿命系数为0.613,屈服极限为603Mpa。     

基于ANSYS的圆锯片模态分析和振动分析

利用ANSYS有限元软件,通过对圆锯片的模态分析,研究其低频范围的横向振动问题.通过软件分析得出圆锯片相应模态下的固有频率和振型.并利用动态信号测试分析系统对圆锯片相应模态的固有频率进行检测,得出圆锯片的固有频率与节圆数和节径数的变化规律,圆锯片边缘的位移矢量和与节圆数、节径数的关系,并指出在不了解圆锯片弹性模量、泊松比和密度等参数的条件下利用动态信号测试分析系统对圆锯片的模态进行检测具有一定的可行性.     

Theoretical and experimental analysis of circular saw tensioning

Summary Tensioning is the saw prestressing procedure most commonly used in the forest products industry to increase the stability of thin circular saws. This procedure stiffens the saw blade by introducing favorable in-plane residual stresses either by local plastic deformation or by local heating. In industry today, rolling is the standard procedure for introducing such stresses.The first part of this paper is concerned with a method of tension evaluation. The method examined consists of measuring saw blade modal stiffness, and it correlates the elastic stiffness of the saw, which approximates the vibration modes, and the natural frequencies associated with these modes. The predictions of the saw frequency shift due to stiffness variations were found to agree closely with experimentally determined frequencies. The method thus offers a practical procedure for tension evaluation and could replace the currently used technique of measuring the light gap under a straightedge placed along the saw diameter.The second part of this paper theoretically analyzes the relationship between the rolling load and the resulting tensioning stresses. The procedure followed in the theoretical model determines the identation load by equating the external power of loading with the power of storing in the elastic zones and of internal dissipation in the plastic zone.The residual stresses obtained by superpositioning the stresses due to unloading were generally in good agreement with the experimentally determined tensioning stresses outside the rolled region. The theory developed can be very useful in predicting tensioning stresses for a given rolling load and roller geometry.List of Symbols a, b Inside and outside saw disc radii - A, B Arbitrary constants - c Saw disc tensioning radius - c_i, c₀ Inside and outside rolling/indentation radii - c_n Neutral radius - d Track width - E Modulus of elasticity or strain energy - E_ext External power of the loading - E_p Power dissipation due to plastic deformation - E_d Power dissipation due to velocity discontinuity - E_e Power stored in elastic zones - f_n Resonant frequency of a saw disc n — nodal diameters - f _n ^TM Measured resonant frequency - f _n ^TC Resonant frequency calculated from the variation in the saw disc stiffness - F Rolling load - H Half saw disc thickness - K_n Modal stiffness, n=number of nodal diameters - K _n ^* Conventional or bending stiffness - K _n ^** Geometric or tensioning stress stiffness - K _n ^T Modal stiffness of a tensioned saw disc - M_n Modal mass, n=number of nodal diameters - M, N Integration constants - P_ave Average indentation pressure - p, p, p' Radial pressures at elastic-plastic boundaries; loading, unloading and residual - p_i, p_O Radial pressures inside and outside the elastic-plastic boundaries The Authors would like to express their gratiude to C. H. Zierdt and J. Rhemrev for assistance in the experimental investigations. The authors are also grateful to Hanchett Co. and California Saw Knife and Grinding, Inc. for supplying stretcher rolls and experimental saw discs, respectively. They are also grateful for the financial support of the project from the U.C. Forest Products Laboratory, California Cedar Products Co., California Saw Knife and Grinding, Inc., Hudson Lumber Co., MacMillan Bloedel Research Ltd., Potlatch Corp., Simpson Timber Co., Sun Studs, Inc. and Weyerhaeuser Co. Finally, the authors thank the National Science Foundation for its generous support of the research     

The effect of rotation speed on the power consumption and cutting accuracy of guided circular saw: Experimental measurement and analysis of saw critical and flutter speeds

ABSTRACT

This paper investigates the effect of rotation speed and vibration response of a circular saw on the sawing process of Douglas-fir wood. An idling test was conducted on a guided circular saw to determine its stable operation speeds and vibration behavior. Short-time Fourier transform analysis was performed on saw idling test data, and variation of excited frequencies of the blade as a function of rotation speed was obtained. The saw blade critical speeds and the rotation speeds that correspond to saw flutter instability were identified. Then experimental cutting tests were conducted at different cutting conditions and the effect of rotation speed and saw vibration response on cutting power consumption and sawing accuracy was investigated. The results showed that conducting a saw idling test and vibration response analysis can identify the saw critical and flutter speeds, which is essential for identifying the optimum rotation speed of circular saw. There was a significant increase in power consumption when cutting at super-critical and super-flutter speed. The effect of rotation speed on sawing accuracy is complex and nonlinear. This effect interacts with feed speed, which makes it difficult to generalize sawing accuracy versus rotation speed in the circular sawing process.     

MR5412型圆锯片气焊加热适张度机工艺与设备的研究

加热适张度是利用氧一乙炔焰,将锯身的一定部位加热,使该部在冷却收缩中产生同辊压张力一样的变形,从而获得适张度。圆锯片气焊加热适张度机配有带锯夹锯装置,可用于圆、带锯的加热适张度及辊压处理,实现了一机多用。经该机修整的锯片,具有作业时间短、适张度均匀且不易消失,锯末端加热部分不易变形,厚度均匀,锯切质量高等优点。     

带锯机锯轮转速、锯条摆动与锯解精度的试验研究

基于对木工带锯机加工特性的研究需要,本文在MJ397型高速木工带锯机的锯条张紧力和进给速度恒定的情况下,通过实测锯机工作台和锯条结构系统的固有频率、同条件下锯割杉木试材时的锯条横向摆动量、变频器调节锯轮转速和锯材表面粗糙度等,分析锯轮转速、锯条横向摆动量与锯解精度的关系,为优化国产带锯机锯割稳定性等设计工作提供依据.     

The effect of saw kerf width on the value of the axial growth stress measured by slitting a log along its axis

The surface growth stress in logs can be determined by slitting the log axially and measuring the outward deflection of the two halves. The saw kerf removes stressed material which generates a compressive strain in the remaining material and thereby reduces the surface growth stress. The purpose of the work is to establish the magnitude of this error. The analysis assumes a uniform compressive stress in the core of the log and a logarithmic distribution in the outer region. The total axial force in the kerf before removal is calculated and, from this, the stress change in the material remaining after kerf removal is derived. Data are presented for a range of kerf widths and for three different growth stress distributions. Direct measurement of the kerf removal error was made by direct measurement of the contraction of the log and by strain gauges to measure the strain. The measured values were close to the calculated values for three growth stress distributions. The analysis yields acceptable values for the kerf removal error. The investigation concludes that for kerf widths not greater than one-tenth of the log diameter, the error in the measured tensile surface growth stress is less than 10%.     

基于ANSYS圆锯片动态性能研究

基于ANSYS软件,对圆锯片进行热力学、静力学和模态分析,揭示各种因素对锯切加工过程中高速旋转状态下圆锯片的影响及其变化规律,从而为研究和改善圆锯片的动态特性提供可靠的理论依据。     

Development of a monitoring system for guided circular saws: an experimental investigation

ABSTRACT

Lack of a monitoring system for guided circular saws marks one of the most critical machines in sawmills as a production bottleneck. Monitoring systems are being researched and developed for machine tools, especially for the metal cutting industry; but there are limited studies on the development of monitoring systems for circular saws in wood manufacturing process. In this study, sensors with the possibility to indicate sawing deviation were chosen that could be mounted in or on the saw guides. The sensors were: a microphone, an accelerometer, temperature sensor, an acoustic emission (AE) sensor, and a newly developed displacement sensor. A load cell was used to measure the lateral force on the guides. The outputs from these sensors were compared to the standard deviation of the board surface measured at the top of the cut. The signals from the displacement sensor, microphone, accelerometer, guide force sensor, and AE senor had no correlation to changes in the sawing deviation as measured by the standard deviation at the top of the board. Under laboratory conditions, the sound level and the AE signal did indicate the beginning and end of the cut. It was found that blade temperature is a good indicator of saw cutting performance. A newly developed temperature sensor can provide accurate temperature of the saw during cutting. The sensor can be used for measuring the rate of heating to cooling over time which can be used as a monitoring system to detect if there is any issue in the system.     

Deviations of kerf by handsaws III: the bend of saw blade by unsymmetrical set

To clarify the inducing mechanism of kerf deviation caused by unsymmetrical set of the handsaw, we hypothesized that the moment on the bottom edge of the saw blade, which is generated by the unsymmetrical set on handsaw teeth, bends the saw blade and this deformation should be one factor of the kerf deviation. To verify this hypothesis, the bend of a saw blade was examined by experiment and by calculation. In the experiments, a model tooth was attached to an actual handsaw. In the calculations, a saw model with a rectangular prism as the model tooth was analyzed by the finite element method. Loads were applied on the model tooth or the rectangular prism. From both the experiments and the calculations, the following results were obtained: (1) the deformation of the handsaw was caused by the unsymmetrical set in the length direction and the height direction of the saw blade; (2) the deformation and the inclination of the blade was larger at the front part of the saw than at the butt part; and (3) comparing the saw handle fixing conditions, the kerf deviation in the sawing line was supposed to be larger in the free handle condition and that kerf deviation in the depth direction was larger in the fixed handle condition. Based on the above results, it is apparent that one of the kerf deviation mechanisms originated from unsymmetrical set on the saw teeth. Part of this report was presented at the 54th Annual Meeting of the Japan Wood Research Society, Sapporo, Japan, August 2004.     

基于ANSYS的发动机支架仿真分析

为进一步改进发动机支架的结构设计，实现发动机支架的CAE标准化生产，本文采用大型有限元分析软件ANSYS对发动机支架的应力分布进行了计算和仿真分析，得出了该构件的应力和应变分布图，从而为发动机支架的强度分析研究提供了比较实用的有限元分析方法。     

The critical rotational speed of circular saw: simple measurement method and its practical implementations

Operation safety during sawing operations as well as dimensional accuracy and surface roughness depend on circular saw dynamic features among other factors such as circular saw blade accuracy and static/dynamic properties of the machine tool. Manufacturers of saw blades have an obligation to mark tools with a value stating the maximum allowed rotational speed for each saw. However, in some cases the value indicated on the saw corresponds to the critical rotational speed or is dangerously close to this critical value. Saw operation at the critical rotational speed is inadvisable and may result in serious injury or depreciation of product quality. This report outlines a simple methodology for evaluation of circular saw critical rotational speed. The assessment was conducted with a camera vision technique on the basis of an impulse test. Results are compared with theoretically calculated critical rotational speeds and the marks on saw blades.     

夹盘直径对圆锯片固有频率的影响

将未适张、辊压适张、锤击适张圆锯片装在不同直径的夹盘上，施以相同的夹紧力后进行振动模态分析。实验证明，不论是未适张圆锯片，还是辊压和锤击适张圆锯片，随着夹盘增大，锯片各阶固有频率都有不同程度的提高，其中辊压适张圆锯片二阶振动模态的固有频率没有增加或只有少量增加，锤击适张圆锯片四阶以上振动模态的固有频率有显著增加。