共查询到19条相似文献，搜索用时 578 毫秒
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林石 《林业机械与木工设备》1996,(4)
锯链切齿绕过导板头时，γ、α２、ｍ发生变化。通过几何分析，推导出一组计算公式．由ＢＧ３３和ＢＨ２９型油锯的角参数变化数据说明，此种影响是很大的。在设计锯链、导板和锉磨锯链时，应予以考虑。 相似文献
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王月仁 《林业机械与木工设备》1979,(3)
△斯蒂尔08S型油锯系一种多用途轻便油锯。拆去导板和锯链,可安装在割灌机、挖穴机和修枝机等机具上。发动机功率为5.5马力;锯链为全自动润滑;导板长度可选用13、16、17和21英寸等尺 相似文献
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林石 《中南林业科技大学学报(自然科学版)》1996,(4)
静止状态下锯链不垂离导板的临界张力与导板轮廓线圆半径和锯链质量线密度成正比．无缓冲器导板的锯链安装张力应比有缓冲器导板的大．锯链和链轮的制造误差可能引起锯链附加张力或松弛下垂．锯链的松弛程度可用趾部间隙来衡量．锯链与导板的热胀冷缩不同步可能引起热张力或热松弛．文章给出了各种张力和趾部间隙的计算公式． 相似文献
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林石 《林业机械与木工设备》1996,(4):22-24
锯甸切齿绕过导板头时、γ、α２、ｍ发生变化，通过几何分析，推导出一组计算公式，由ＢＧ３３和ＢＨ２９型油锯的角参数变化数据说明，此种影响是很大的，在设计锯链，导板和锉锯链时，应予以考虑。 相似文献
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本刊记者 《林业机械与木工设备》1982,(6)
一般的油锯都将发动机、锯导板和锯链固定在发动机本体上,而发动机本体则装在柔软的壳体中以达到第一次减振;壳体与把手之间采用橡胶隔振元件达到第二次减振;把手上包覆防振橡胶达到第三次减振。尽管如此,减振效果并未达到理想的要求,油锯的振动对油锯手的身体健康 相似文献
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我国木材生产行业所使用的汽油动力锯，有以 ０５１型为代表的高把油锯和引进技术生产的矮把油锯，还有一种两个人抬着使用的长链油锯（现已很少使用）。 几十年来，我们在使用油锯的过程中积累了许多经验，也有血的教训。下面以最常用的０５１型油锯为例谈谈其使用经验。１使用新锯１．１作好验收和首次启动 出库一道新锯，首先应认真地检查它的外观，将各部紧固件试着用工具再紧固一遍，导板应平直，汽化器、火花塞和随机工具应齐全完好。用手拉动锯链时，应感到锯链在链槽上滑动自如又不松驰。外观检查正常时就可准备启动。 启动油锯前，… 相似文献
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导板是油锯的切削部件之一,主要用以支承锯链。导板的设计,在锯机自重较大的发展初期,为了减轻工人的劳动强度,多侧重于重量的减轻,因之出现了中空等形式的导板(如051导板)。随着锯机自重的减轻,导板设计制造水平的提高,导板有了较大的变化,如为减少锯链紧边的摩擦和松边的撞击,导板尾部变窄;导板头部半径缩小,使导板趋向细长型发展。因之,现阶段导板的设计更侧重于进锯快、耐磨性好和使用寿命长。现仅就有关导板的几个设计问题谈谈笔者的体会。 相似文献
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Resonance frequencies of bars with various types of end supports were examined in terms of flexural vibration. Sugi (Japanese cedar, Cryptomeria japonica D. Don) was used for the specimens. Small rectangular bars with dimensions of 25?mm (R)?×?5?mm (T)?×?300?mm (L), small round bars of 25?mm in diameter and 250?mm in length, actual-size rectangular bars with the dimensions of 45?mm (R)?×?95?mm (T)?×?1500?mm (L) and actual-size round bars of 180?mm in diameter and 2000?mm in length were made. Varying compression stress was applied to the parts around both ends of test specimen, whereupon flexural vibration tests were performed. The measured resonance frequency rose rapidly early in the increasing compression load process and was nearly stable for the larger compression load. The significant increases in the resonance frequency for round bars are thought to be derived from the wide area between the round bar and jig. It is necessary to compare the resonance frequency of a bar tightly fixed to a post with that of the same bar loosely fixed to the post. 相似文献
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The xylophone is a percussion instrument made of vibrating wooden bars, the free ends of which can be struck by a mallet. The cross section of xylophone bars is not uniform for tuning purposes. The aim of this study is to impart a better understanding of the frequency shift phenomenon in acoustic resonance of xylophone bars during their tuning operation. A new analytic approach is, therefore, proposed based on the presence of one or several defects (weak elements) in a bar considered as a one-dimensional system in free–free longitudinal and transversal vibration. A weak element mechanically represents one or several real structural irregularities in the wood; this element corresponds to a mechanical behaviour analogy. This weak element is physically characterized by two positional parameters and by its Young’s modulus. Dynamic tests and numerical computations by the finite elements method give results in good accordance with those of the weak element method. It is shown that when the element weakens, the natural frequencies decrease. Furthermore, the frequency shift depends on the weak element position along the bar. It is also reported that longitudinal and transverse dynamic behaviours are similar regarding the presence of a weak element in a bar. 相似文献
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对淬火前的热挤压棒用不同的冷拉拔量进行拉拔，结果表明；冷拉拔量对棒材的组织和性能有不同的影响．当变形量达到10％时，经淬火后的棒材其组织是均匀的细晶组织． 相似文献
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This study examined whether or not weight, density, and Young’s modulus can be accurately measured by vibration test without weighing beams for timber guardrails. Bending vibration tests with and without the concentrated mass were performed on small clear round bars without the pith of spruce and cedar and on actual size round bars with the pith of cedar for the timber guardrail. The following results were obtained. The vibration method with additional mass could be applied to the round bar as well as the rectangular bar. It is possible that resonance frequency was decreased by the sawn split in the horizontal tapping. It is believed that the free ends condition is easier to realize than the fixed ends condition for cross beams for timber guardrails. The weight of the cross beam for the timber guardrail could be accurately estimated by the vibration method with additional mass under several testing conditions. 相似文献
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应用ADAMS软件完成移栽机用凸轮摆杆扶苗机构的实体造型,求出凸轮的轮廓曲线、组合摆杆的运动规律和运动特性。并对机构进行运动分析和仿真,为凸轮摆杆机构的设计提供一种有效的方法,可缩短设计周期,提高设计质量。 相似文献
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环境舱是用来检测木质家具及装饰装修材料中甲醛、苯系物等挥发性有机化合物释放量的设备。环境舱的分隔门密封装置由操作机构、传动链与密封袋等部分组成。密封段分为4个直线段和4个扇形线段，其共同组成内舱截面轮廓。操作机构由手轮、手轮轴等组成，驱动盘有8个曲柄，它们与相应的连杆、压紧杆共同组成传动链的8个曲柄滑块机构，其能实现各个密封段的同步动作。密封装置的大部分置于分隔门的内腔中，这样可减少其对工作舱中相关气体的吸附，有利于提高检测结果的准确性。 相似文献
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构造简单，安装方便，荷载作用下稳定性比较好的扣件式钢管支架，是目前桥梁施工中应用最广泛的一种支架。现就使用前在组合荷载作用下，格构式钢管支架整体稳定及单根钢管立杆局部稳定进行验算。安装时，支架立杆的纵距、横距及水平杆的步距要根据验算结果进行。安装顺序，立杆沿桥纵向由一端向另一端，水平杆由下向上进行。支架安装完成后，应做预压试验，以检查支架的压缩量及稳定性。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(2):193-200
Abstract Chainsaws are widely used for timber harvesting operations. Vibration transmitted into the operator's hand and arm system by the chainsaw's handle can cause vascular and neurological disorders. This article presents the results of operator vibration exposure to three different chainsaws, equipped once with conventional and once with Kesper safety bar. Measurements were done simultaneously on saws' front and rear handle, both for sharpened and blunt chain, as well as for three operational modes being cutting, limbing, and idling. Measurement and analysis of vibration were carried out according to the guidelines of ISO 5349-1 and ISO 5349-2. The results show that root mean square (rms) vibration acceleration was highest in the x-axis for front (in the vertical direction relative to the chainsaw – up though the hand) and in the z-axis for rear handle (perpendicular to the grip, up through the hand into the arm), respectively. For all measurements, vibration at the rear handle exceeded that of the front handle. Differences in vibration between saws equipped either with Kesper safety bar or with a conventional bar were not statistically significant. Frequency-weighted vibration (values for sharpened chain) for cutting was between 4.39 and 4.96 m/s2. During delimbing values between 4.93 and 5.04 m/s2 were recorded. Vibration for idling saw ranged from 5.87 to 6.15 m/s2. 相似文献