密裁板锯噪声研究

According to ZBJ65015-89 standard about noise level testing method of woodworking toot, the noise testing for MJg0# and MJCl125 precision panel saws was conducted by using model ND2 precision soundqevel apparatus and double frequency wave filter. The testing results showed that the unloaded running noise source of precision panel saw was mainly from main saw blade and its aeromechanic noise was the largest. The rotating speed was determined as an important factor to impact dynamic characters of precision panel saw as the unloaded running noise increased along with speed increasing. For reducing noise of precision panel saw, the first important way is to reduce the aeromechanic noise produced by main saw blade rotating at high speed; based on assuring the processing precision, choosing tow speed is a better way to drop dawn noise; from the view of design, the diameter of clamping lid is better of half of outer diameter of main saw blade.     

木工圆锯机噪声及控制

分析了木材企业中木工圆锯机噪声的来源和对人体的危害，提出了通过改进圆锯机机床结构，锯片结构及齿型等措施，可大大降低圆锯机的噪声强度。     

硬质合金圆锯片的噪声及其降低措施

分析了硬质合金圆锯片的噪声来源、锯片噪声测量方法及降低噪声的措施,通过试验验证了降噪措施的可行性。     

国际制材行业环境噪声研究现状与展望

本文介绍了美国、瑞典、日本、英国等国家制材行业环境噪声的研究状况；重点介绍了东北林业大学课题组对黑龙江、吉林两省的１３个制材车间的环境噪声进行测试、分析与评价的结果，并提示了我国制材行业环境噪声的现状及其特点，提出了我国制材行业降低环境噪声的方法和途径。     

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     

精密推合锯动态特性的研究──噪声测量与分析

通过对牡丹江木工机械厂生产的ＭＪＣ１１２５精密推台锯的测试,找到了该类型机床的主要噪声源,并得出了空运转时随着转速提高噪声也提高的变化规律。     

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.     

发达国家油锯技术发展现状与展望

本文介绍了诸如增压式化油器、空气净化、微电脑、自动化润滑、双级减振系统等新技术在油锯设计制造中的应用,针对油锯废气排放、微电脑应用等问题,提出二冲程汽油机仍将被广泛采用,新一代的油锯将应用更多的新技术,从而发展出更方便、更安全、更有效的林木采伐机械。     

Comparing model-based approaches with bucking simulation-based approach in the prediction of timber assortment recovery

The aim of the study was to compare model-based approaches inthe prediction of timber assortment recovery with bucking simulationbased on detailed stem data. A correction function for the totallength of saw log fragments and two optional saw log reductionmodels, that is, the MELA96 version and MELA05 version, wereapplied. In the bucking simulation, the volumes by timber assortmentswere calculated using a bucking-to-value simulator. The predictionof saw log recoveries varied between the bucking simulationand different versions of saw log reduction models. The levelof the reduction from the MELA96 version was at the same levelas from the bucking simulation where defects were taken intoaccount, but the saw log reduction had a very low variance dueto a small amount of independent variables. The saw log reductionof the MELA05 version included more variation although the levelof the reductions was higher and the variation did not meetwith the bucking simulation. As a conclusion, the model-basedapproaches seem applicable at least for the prediction of sawlog recovery in the large area forest inventories where thevariance of the standwise timber assortment recoveries neednot be predicted.     

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).     

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     

油锯离心离合器的优化设计

本文根据油锯离心离合器的工作原理和生产上的要求,探讨了以减小重量为目标函数的优化设计方法,建立了数学模型。经对实例进行计算表明,本法可使离心离合器的重量减小近16%。如果适当调整其性能参数,则其重量可减小36%。本设计方法对改善我国油锯的整机性能具有现实意义。     

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。     

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     

校园环境噪声监测与评价--以华中师范大学为例

环境噪声是环境质量评价的重要指标。通过噪声监测实验,记录了华中师范大学校园内的噪声污染数据,根据国家标准评估了校园环境噪声状况。试验采用网络剖分法,分别于昼间7:30~10:00和夜间22:00~22:55两个时间段对等效声级进行了测定。实验结果表明:昼间噪声污染更为严重,平均噪声超标率达到26%,夜间噪声污染相对较轻,但噪声超标率也达到19%。校园内不同功能区的噪声来源不同,工程施工产生的噪声是主要的污染源,影响比重达到58%。根据实验结果,校园声环境质量一般,需要对现状提出合理的改进建议。     

Seasonal effects of prescribed burning and roller chopping on saw palmetto in flatwoods

Shrub encroachment has become a problem in many rangeland systems across the United States due to a reduction in the disturbances, primarily fire, which historically maintained them. The shrub saw palmetto (Serenoa repens) has become abundant in many habitats of the southeastern Coastal Plain, including Florida. When fire regimes are altered or fires are suppressed, this species can proliferate leading to significant changes in the ecosystem, particularly the herbaceous vegetation. Prescribed burning and roller chopping are management activities often used to control saw palmetto. However, little is known about the effects these treatments have on this shrub, particularly when applied in different seasons. We compared the seasonal effects of prescribed burning, roller chopping, and combinations of the two on saw palmetto. The effects of treatments on saw palmetto were assessed using a paired-sample approach, where saw palmetto height, cover, and density were compared between sampling locations randomly located within treated (e.g., burned) and untreated areas. Dormant season burning had no effect on saw palmetto density and height and only temporarily reduced cover, with rapid regrowth occurring the first year post-treatment. Growing season burning also had no effect on saw palmetto density. However, saw palmetto cover was lower on growing season burn compared to control sites the first year post-treatment and height the first and second year post-treatment. The combination of burning and roller chopping, despite having no effect on saw palmetto density, did result in lower saw palmetto height compared to controls the first and second year post-treatment. The effect of roller chopping/burning on saw palmetto cover depended on season and year. Saw palmetto cover and height were lower on dormant and growing season roller chop than control sites the first and second year post-treatment, but only growing season roller chopping had an effect on saw palmetto density. The single application of a dormant or growing season burn is not recommended for control of high-density saw palmetto, however, it may be suitable to maintain areas where saw palmetto levels are low and proliferation of the species is not a threat. Dormant and growing season roller chopping showed the greatest potential for rapid saw palmetto control. Growing season roller chopping is recommended if significant reductions in saw palmetto density are desired.     

毛竹食用菌复合经营模式研究

利用毛竹林生态环境条件,以竹笋加工废料笋壳为培养基质,进行食用菌生产试验。结果表明,以笋壳作为培养料的平菇、榆黄蘑产量分别为592.59 kg/100 m²、187.50 kg/100 m²,分别占同样条件下以木屑作为培养料所获产量的44.06%和20.15%;以笋壳作为培养料的食用菌生产经历了2潮明显的出菇高峰,时间周期短而集中;而木屑培养料的食用菌则经历了3潮明显的出菇过程,时间周期较长。在产量方面,虽然平菇比榆黄蘑产量高,但榆黄蘑的市场价格较高,因此也值得推广。与木屑相比,笋壳具有生产成本低、生态环保、市场潜力大等优势,具有很高的潜在利用价值。     

MJ256型圆锯机的噪声测量与分析

本文采用先进的计算机噪声测量分析系统，对MJ256型圆锯机的噪声进行了测试和分析，找出了主振源，并重新设计制造了一个排屑器门，使锯机最大声强值降低两个多分贝。     

Idling noise from circular saws made of metals with different damping capacities

Circular saw construction using materials with high internal damping has been found to be an effective way to suppress whistling noise during saw idling. A high-damping alloy called Silentalloy (12Cr-3Al-Fe) was previously shown to be an effective material for this purpose. Tests with Silentalloy suggested that a logarithmic decrement of at least 0.07 is needed. Silentalloy does have some disadvantages, such as modest strength, difficult heat treatability, and special order status. The purpose of these experiments was to confirm the general applicability of the minimum effective logarithmic decrement of 0.07 and to find more practical metals for saw-blade construction. Three commercially available metals of different damping capacity were selected. The idling noises of saws made of these metals were compared with those of saws made of typical saw steel and Silentalloy. The minimum logarithmic decrement for whistling-noise suppression was found to be approximately 0.01. On a logarithmic scale, this value is similar to the 0.07 value previously found for a Silentalloy saw. A ferromagnetic steel (20Cr-3A1-Fe) was found to be a useful alternative to Silentalloy from the viewpoint of strength, but the cost of this steel makes it unsuitable for mass production. The success in identifying an effective alternative material to Silentalloy provides encouragement for the identification of other high-damping alloys among the 13Cr-Fe to 18Cr-Fe series without the cost disadvantage of ferromagnetic steel.     

Potential biomass and logs from fire-hazard-reduction treatments in Southwest Oregon and Northern California

The FIA BioSum model was used to simulate three fire-hazard-reduction policies in an area comprising northern California, southwestern Oregon, and the east slopes of the Cascade Mountains in Oregon. The policy scenarios, all subject to a stand-scale fire-hazard-reduction effectiveness constraint, included maximize torching index improvement (Max TI), maximize net revenue recovery (Max NR), and minimize merchantable timber removal (Min Merch). Differences in the area treated under each scenario were considerable, ranging from 15 to 96% of the area for which effective treatments are technically feasible. For each scenario, weight, species, and source tree size of both dirty chips (hogfuel or biomass) and saw logs were estimated. The mix of species and sizes removed under each scenario was surprisingly similar, although the Min Merch scenario did remove more noncommercial species such as hardwoods and more saw logs in the midsize classes (10 to 16in. diameter at breast height (dbh); 25.4 to 40.6cm) than the other two scenarios. Saw logs accounted for 67 to 79% of the weight removed. Under all scenarios, the Douglas-fir (Pseudotsuga menziesii)/larch (Larix) and white woods (Picea spp., Tsuga spp, and Abies spp.) species groups accounted for nearly all of the saw logs removed. Tops and limbs of commercial species and noncommercial species accounted for most of the dirty chips. Stems of low value commercial conifers (7 to 16in; 17.8 to 40.6cm) were also an important source of dirty chips. Trees smaller than 7in. (17.8cm) dbh were a relatively minor component of the dirty chip mix.