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.     

木工带锯条的动态张紧力测量与分析

提出一种验收调整带锯条动态张紧力范围的方法,该方法实测带锯条在静态和动态下的固有频率,据此用弦振动公式推算出带锯条的静态和动态张紧力,其推算精度与调整带锯条张紧力范围吻合。本文用弦振动简化理论模型给出的规律符合木工带锯条张紧力和固有频率间的实际情况,所提出的测量动静频方法,可以作为调整带锯条动态张紧力验收手段这一问题的研究和工程应用。通过激振的方式检测带锯条的固有频率,判定其张紧状态,进而实现带锯条张紧的动态调整,对木工带锯条理论的深入研究和装备技术的改进有指导意义。     

木工适张带锯条的振动分析

应用振动理论,对经过适张处理后的木工带锯条进行研究,确定张紧力与系统固有频率之间的关系,提出将带锯条的振动简化为弦的振动与受拉伸的梁振动.用电测法测应变换算张紧力,用频谱分析法测量系统的固有频率,理论解得到试验支持,同时计算张紧力和张紧应力.     

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.     

木工带锯条系统固有频率声学测量

采用声学测量法测试木工带锯条系统的固有频率,对带锯条研发与检测技术具有一定的应用价值,并为各类木工机械与刀具系统的固有频率测试提供借鉴的方法.     

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。     

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。     

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     

Aerodynamic sound and self-excited vibration of circular saw with step thickness I: Comparison of dynamic characteristics between the common circular saw and the circular saw with step thickness

The natural frequencies, aerodynamic noise, whistling noise, and self-excited vibration between the common circular saw with uniform thickness and the circular saw with step thickness (thin on its outer part and thick on its inner part) were researched during idling. The natural frequencies of the circular saw with step thickness increased with an increase in the thickness and in the radius of the thick part. The frequencies of the circular saws with step thickness (thick at the inner part) were higher than that of the thin circular saw with a uniform thickness of 0.5mm. The aerodynamic sound pressure level induced from circular saw teeth increased with an increase in the tooth thickness. The whistling noise and self-excited vibration easily occurred in the thick circular saws (1.5, 2.0, and 2.5mm). The whistling sound pressure level and the vibration amplitude increased with an increase in the thickness of the saw. None of the designed circular saws with step thickness generated whistling noises or self-excited vibration during idling.Part of this report was presented at the 45th annual meeting of the Japan Wood Research Society at Tokyo, April 1995 and the 12th International Wood Machining Seminar at Kyoto, October 1995     

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。     

Theoretical analysis of bandsaw roll-tensioning

Bandsaw roll-tensioning was theoretically analyzed by amplifying Aoyama's fundamental equations. In the analysis the accumulated amount of tension after several roll-stretching passes was expressed as the linear accumulation of the amount of tension at each roll-stretching pass. The same condition was applied for the expression of the accumulated amount of crown back. The relations between the distance from the gullet in the transverse direction of the bandsaw blade to the roll-stretching point and the distance from the gullet in the transverse direction of the bandsaw blade at which the amount of tension becomes maximum, minimum, or zero were clarified. To meet the requisites to adjust the amount of tension at an arbitrary distance in the transverse direction of the bandsaw blade or the amount of crown back, an adjusting procedure was developed. The process of bandsaw roll-tensioning can theoretically be controlled by this procedure.     

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).     

带锯机张紧系统锯条横向振动特性的研究

本文对带锯机杠杆压砣式张紧系统压砣及锯条横向振动进行了测试，并运用DASP6．53振动分析软件对测试结果进行了分析，得到了带锯机杠杆压砣式张紧系统振动的特性、产生振动的频率范围及频率特性，为今后带锯机的动态设计奠定了基础。     

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.     

隔振器式杠杆压砣张紧系统带锯机锯条振动的分析

隔振器式张紧系统带锯机是在原杠杆压砣式张紧系统带锯机的基础上加以改进而形成的一种新式带锯机。通过采用MATLAB软件对带锯机锯条振动实验数据进行分析,从而证明改进后的带锯机锯条振动明显小于原杠杆压砣式带锯机。     

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.     

Experimental verification of bandsaw roll-tensioning theory

The validity of a bandsaw roll-tensioning theory developed by the author is verified based on a model experiment. It is shown that the actual roll-tensioning process can be clearly explained by this theory. Roll-stretching force transmission coefficients are introduced in this theory. These coefficients, which indicate the magnitude of the compression force parallel to the bandsaw surface at the roll-stretching position, are affected by the thickness of the bandsaw blade, the radius of the bandsaw blade vent at the measurement of tension, and the straightness of the bandsaw blade at the measurement of crown back, among others. For the practical use of this theory, therefore, it is necessary to determine the proper magnitude of these coefficients based on tensioning experiments.     

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     

Determination of shear modulus on construction size timber

Shear modulus determination of construction size timber was examined. Three different Techniques were used: torsional vibration, simultan E&G, and variation of span technique. We found that the simultan E&G technique is quite sensitive to the error of natural frequency determination and provides only an estimate for G. Better shear modulus determinations are the static and torsional techniques, but the torsional technique is most precise. The torsional vibration technique can be a good solution for shear modulus determination in an industrial environment because it provides quick and precise etermination, but standardization of the method would first be necessary. We found a high correlation coefficient (0.80) between the screw withdrawal resistance and shear modulus of 2 by 4 timber. Based on this result it is possible to estimate the shear modulus of timber even if the timber is installed in a structure.This study was conducted with financial support of the Science and Technology Agancy Japan via an STA fellowship     

硬质木材榫槽组合铣刀设计的研究与实现

为解决小型台式多用木工机床加工硬质木材榫槽难的问题,设计了一款组合铣刀.以数块窄刀刃圆锯片组合代替宽刀刃,多刀刃代替双刀刃,组合时锯齿刀刃错位排列,各段直刃呈螺旋状,采用大前角改善切削性能,齿廓优化成刨削锯齿状以提高锯齿的耐用度和使用寿命.该铣刀具有分块式切削刀刃,切削性能优良,加工硬、软质木材榫槽时的进料速度比直齿双刃盘式成型铣刀提高3倍.