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木工圆锯噪声属高频强噪声,其频谱有两大特点(见图1A线):一是负载声级高,平均值在110分贝(A)左右,峰值可达115—120分贝(A);二是频率范围宽,峰值分布在1,000—8,000赫兹的高频区内。因此,圆锯噪声对人体危害很大。据国内外资料介绍,如选用其中一条或数条措施,便可收到一定的降噪效果。 1.用镶硬质合金锯齿的锯片(下称镶齿锯片)代替高碳工具钢锯片(下称普通锯片),平均噪声级可从110分贝(A)降到96分贝(A)(见图1B线)。 2.在普通锯片的锯面上涂上一薄层阻尼涂料(一般是粘弹性的聚合物),可使噪声级降至94分贝(A)(见图1C线),同时还能延长锯片… 相似文献
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中国吉林森工集团松江河林业有限公司是全国大型森工企业之一.公司现有职工16 000余名,公司下属林场、贮木场、制材厂、纤维板厂等40余个基层单位、300余个工段(队),担负着年产17万m3的木材生产任务. 相似文献
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我厂成批生产的定型产品MJ223摇臂式手拉圆锯机,是用3千瓦功率、2,860转/分转速的专用木工电机,其锯片直径 D=350毫米,锯片厚t=1.8毫米。内孔径d=25毫米,材质是65Mn(弹簧钢)制作的,齿数Z=100,齿形如图1所示。试车运转时,锯片发出刺耳的尖啸声,据测其空载噪声为95-98分贝(A)。 为控制产品噪声,我们对圆锯片采取了开消声沟槽措施如图2。沿锯片周围齿底部分别开四条长25 毫米,宽3毫米 等距离的沟槽, 沟槽与锯孔中心 线呈15°的倾斜 角。由于锯片开 槽,使锯片旋转 时形成的压缩空 气由沟槽流出。 改变了锯片的振 动模式,减弱了 锯片本身振动… 相似文献
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前言为了提高木材加工企业的生产安全性,确保圆锯机操作者的作业安全与健康,并便于各单位实施GB16272《木材加工圆锯机安全技术要求》,现将其主要内容作如下介绍。1一般要求1.1锯轴的额定转速不得超过圆锯片的最大允许转速(见附录A)。1.2圆锯机上的圆锯片必须配有安全防护罩。1.3工作台面镶板一般排列在圆锯片的两边,镶板应由有色金属、塑料或木材等较软材料制成,并可以更换。1.4工作台上的锯片槽口宽度一般为锯路宽度加10mm,倾斜锯为锯路宽度加15mm。1.5对可能造成人身伤害的圆银机的传动部件必须设有安全防护装置。1.6锯… 相似文献
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木工锯木材,有时会发生木材突然倒退飞出,撞击木工腹部、胸部,或砸伤手指,造成腹部闭合性损伤,手指残废等后果。出现这种现象的主要原因是: 1.夹锯:锯路太窄,木屑排出不畅;木材含油质较多或纤维坚韧;锯路加水不足;锯片局部变形等,都会造成夹锯。如助手端装有锯尾刀(又称安全刀),或者夹锯时助手能及时将本棋打进锯路,以及切断锯床的动力使锯片停止转动,均可避免木材飞出。如果锯工松手、将木材倒退,或者助手将木材推向锯工,都是危险的。 2.锯齿久用磨损,高低不匀,锯硬质木时容易引起木材上下跳动,突然飞出。 3.木纹扭曲或木材锯路产生偏曲时,… 相似文献
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南平水泥股份有限公司(前身南平水泥厂),是五十年代建成投产的本省首家国有水泥企业,现为省级百家重点企业之一,公司现有职工1423人,资产总额约4亿5千万元.主要设备有一条日产700吨熟料带窑外分解干法生产线和四台湿法回转窑,水泥产量从50年代的3.5万吨/年发展到现在年产60万吨高标号水泥,水泥粉磨能力达100万吨/年以上,跨入国家大型建材行业.公司石灰石矿山是全国首家正规进入地下开采,开采量从原有年产4万吨发展到现在年产40万吨能力. 相似文献
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某花岗石厂引进的花岗石生产线,1988年2月试生产时,锯机车间粉尘污染严重,工程验收时因不符合卫生要求,未通过验收。该生产线是1987年从意大利引进的。两台SB型摆式框架锯机,采用砂泵自动供浆循环喷浆防尘,其喷浆装置安装在砂锯的顶部,喷浆口距石料3m,适于加工2.2m高的石料板材。但实际上石料装锯高度多在0.9~1.3m,锯机喷浆口距石料1.7~2m,造成砂浆飞溅,加上摆式框架的运转,整个车间粉尘飞扬。1988年2~9月对车间粉尘作业点采样测定,19个样品中,浓度为2.5~34mg/m~3者16个(粉尘中游离二氧化硅含量均在10%以上),2mg/m~3以下者3 相似文献
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2007年,平安城市建设无疑为安防行业带来了巨大的商机与发展机遇.无论是传统的DVR监控厂商还是现在的后起之秀IP监控厂商都将目光瞄准了这块大蛋糕.平安城市视频监控系统规模庞大,覆盖范围广,一个城市动辄安装成千上万,乃至数十万个监控摄像头,意味着监控系统中包含了数十万路视频图像,这些图像通常涵盖了整个城市的街道、广场、社区、能源、交通等重要场所. 相似文献
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输油管道动火的安全管理 总被引:3,自引:1,他引:2
针对东北管网30年来动火施工安全管理方面的经验,总结近年来在动火安全管理上采用的新的管理模式所取得的成效,提出石油管道企业风险程度最高的输油管道动火施工安全管理动火准备、动火施工投产的责任界面划分、动火施工投产组织机构的建立、施工现场的安全管理等一整套科学动火方法和理念。通过对输油管道动火施工这一高风险作业管理实现了低风险操作,实现了本质安全。 相似文献
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以Fanger等人建立的预告平均票数(PMV)、温斯洛提出的不舒服皮肤湿度指教(DISC)和有效温度指数(ET★)为基础。阐述了A.P.Gaggcr等人建立的人体对衣内热环境反应的新标准预测指数PMV*。在此基础上。详尽分析了与人体舒适性密切相关的温度指标和感觉指标。同时也对原预告平均票数(PMV)与新的预告平均票数(PMV★)进行了深入细致的比较,探讨了PMV★及新的舒适一温度图的适用性。 相似文献
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Saad A. El-Sayed Ahmed M. Abdel-Latif 《Journal of Loss Prevention in the Process Industries》2000,13(6):509-517
The critical temperature as well as the critical flux for ignition of a dust layer of cornflour and a mixture of wheatflour and cornflour (80% wheatflour+20% cornflour) on a hot plate have been determined. The moulded sample was cylindrical in shape and of different heights and diameters. The particle size of dusts ranged between 63 μm to 150 μm. The temperature–time histories for self-heating without ignition and with ignition are offered, showing the critical boundaries between them. Also the times to ignition for each dust, showing the effect of sample size on their values, are determined. Certain experimental correlations which relate to times to ignition, as well as the critical temperature for ignition and thermal and geometrical dimensions of sample are presented. 相似文献
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Experimental studies of boilover were conducted in small scale rig at Universiti Teknologi PETRONAS (UTP), Malaysia and Loughborough University, United Kingdom. The study at UTP was aimed to demonstrate the ability of conducting tests at a smaller scale to simulate the boilover phenomenon. At Loughborough University, a novel laboratory scale rig was designed and built in order to obtain visual records of fuels' behaviour in a pool fire. The ultimate objective of these studies is to develop a greater understanding of boilover pertaining to fires involving the contents of storage tanks. Fuel mixtures containing light and heavy components were burnt as to study the feasibility of reproducing hot zone formation and boilover in a smaller scale and a safe environment. Boilover occurred after certain period of burning. It is found that thickness of the hot zone changed with time. It is also found that the time needed to start boilover increased when fuel thickness increased. The visualization of the fuel behaviour during the experiments was obtained to better understand the formation and growth of hot zone, the boiling of water layer and hence the boilover occurrence. Based on the data analysis and the photographs recorded from the experiments, the laboratory scale experimental rig could be used to simulate the hot zone formation mechanism and the boilover event safely and successfully. Such information are important for the understanding towards boilover phenomenon. 相似文献
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高温烟气除尘用纤维滤料研究进展 总被引:3,自引:0,他引:3
本文对上程上高温烟气来源进行了分类,对当前高温烟气过滤的核心技术的耐高温过滤材料的使用现状进行了分析,对高温玄武岩纤维过滤材料进行了重点探讨与展望,指出玄武岩纤维滤材当前在高温烟气过滤行业中急需解决的问题和产业科技成果转化方向。 相似文献
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《Journal of Loss Prevention in the Process Industries》1999,12(2):125-136
In an exothermic reactive chemical storage tank, a thermal explosion can occur when the heat generation within the storage tank is greater than the heat removal from the storage tank. In a solid system, the existence of an inflection point in the temperature versus time curve is often used as a criterion for thermal explosion. In this study the applicability of this criterion to fluid storage is examined by investigating the hot spot in the system. Transient natural convection of an exothermically reactive fluid in a vertical, cylindrical storage tank with isothermal walls is investigated numerically. The axisymmetric 2-D Navier–Stokes equations governing the flow fields are reduced by introducing the stream function–vorticity formulation and solved by the alternating-direction-implicit (ADI) technique. The reactive heat sources are represented by a zeroth-order rate expression with an Arrhenius-type rate constant. It is found that the hot spot is no longer located in the center of the tank due to the buoyancy effect. In a particular range of Rayleigh number and Frank-Kamenetskii number, the hot spot is found to move periodically. A stable steady regime, stable oscillatory regime and thermal explosion regime can be specified based on the dependence of the critical Frank-Kamenetskii number on the Rayleigh number. In the stable oscillatory regime multiple inflections in temperature versus time are found. Therefore, the existing criterion, which defines thermal explosion by the appearance of an inflection in the temperature versus time curve, is no longer applicable in reactive fluid systems. The results of nonconvective systems do, however, provide a preliminary and conservative estimate for thermal explosion of a reactive storage tank. 相似文献
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前言 2003年春节前后,枣庄市相继发生数十起热水锅炉鼓包事故,其中有八起鼓包锅炉出自某一结构,同年3月8日,枣庄市某学校又一该结构热水锅炉在使用仅6个月后发生锅筒鼓包、局部裂纹以及水冷壁管堵塞渗漏事故.给推广使用这一结构类型锅炉蒙上了阴影,笔者作为多年从事锅炉与水处理检验的技术人员从该台锅炉的使用管理与锅炉结构入手,通过分析论证,发现鼓包锅炉普遍存在着一些共性问题. 相似文献