LOAD DISTRIBUTION ON DRUMS OF DOUBLE DRIVE BELT CONVEYOR

The double drum drive is widely used on the mine belt conveyor, which are divided the rigid connected double drums and separately driving double drums according to connected method of two drums. Because of the change of real work condition, the load distribution is changed on the two drive drums, which may produce a slippage between a drum and belt. Slippage may intensify the wear of the drum, and sometimes causing the fire of the belt. This restricts the development toward narrow belt, high velocity and large power of belt conveyor. In this paper, the factors affecting the load distribution of two drums of double drum belt conveyor are systematically analyzed and some computing formulas derived, by these formulas, the actual lcad distribution on the two drums of rigid connected or separately driving belt conveyor can be separately calculated.These formulas also can be as the theory base for adjusting the driving force of two drums.

Energy and Exergy Analysis of a Finned-Plate Double Pass Solar Air Heater with Different Arrangement

The present work investigated the solar collector system with triangular longitudinal fins fixed to the absorber surface at different configuration. Four models of collectors were manufactured with different absorber plates made from aluminum material. The experiments were carried out at the winter session in the climate of Iraq—Ramadi city with longitude (43.268) and latitude (33.43). The experiments have used three values from (0.027 to 0.037) kg/s. The results showed that the temperature difference increases gradually until midday and begins decreasing gradually until it becomes zero at sunset. Maximum temperatures difference has been obtained at the fourth type which is (20.6 °C), and maximum efficiency and exergetic efficiency (99.9%), (43.08%) respectively. A comparison has been made with previous works for thermal and exergetic efficiency. The comparison showed good compatibility between results; the percentage of error does not exceed 3%. The results proved that the existence of fins was a good technique for enhancing the thermal performance of double pass solar collector with a non-effective increase in pressure drop.

EFFECTS OF SOIL MOISTURE CONTENT ON DRY NURSERY SEEDLING QUALITY OF LATE DOUBLE CROPPING RICE IN SOUTH CHINA

In the present paper, an experiment was conducted to study the effects of soil moisture content on dry nursery seedling quality in Guangzhou in 1995. Through comparing the difference of dry nursery seedlings and wet nursery seedlings, we found a close relationship between soil moisture content and seedling growth. The seedling emergence of dry nursery seedling was more even, tidy and faster, and the survival rate was higher than that of wet nursery seedling. Dry nursery seedlings had small plant stature, slow leaf stretching speed and low individual seedling dry weight, but had high dry/fresh weight ratio. This was abeneficial factor for seedlings to recover from transplanting shock more quickly. As com-pared with the wet nursery seedlings, dry nursery seedlings had poor rooting ability,but had more vigorous white roots and fewer rust roots. It was the possibly important reasonfor dry nursery seedlings to form strong“explosive force”.

EFFECTS OF SEEDING DENSITY AND BASIC MANURE ON THE GROWTH OF DRY NURSERY SEEDLINGS IN LATE DOUBLE CROPPING RICE IN SOUTH CHINA

During the period of dry nursery seedling raising of late double cropping indica rice in South China, both chemical fertilizer and farmyard manure did not show obvious effect on the growth of shoot and root in young seedlings at 4-leaf stage （18-day-old seedling）, but had significant effects on root growth in old seedlings with 6-7 leaves （27-day-old seedling） at suitable seeding densities (65-125g m-2). There were satistically significant differences （at 0.01 or 0.05 levels）between treatments in root number and rooting ability of root-pruned seedlings.

Multiple Phase Change Materials for Performance Enhancement of a Solar Dryer with Double Pass Collector

The fluctuation in drying temperature influences the food products’quality and drying time significantly during the drying process using an indirect solar dryer.One of the effective methods to reduce these variations in the temperature is based on thermal storage materials to control the drying temperature.An experimental investigation is presented in this study to evaluate the performance of an indirect solar dryer with air double pass using multiple phase change materials(PCM)as thermal storage materials.Two PCMs with different melting points are used to store the available heat energy during peak sunshine periods and reduce the drying temperature fluctuations.Drying tests on a food product sample are conducted in three cases,the first was without PCMs using natural convection.The second and third cases are based on forced convection with and without using multiple PCMs under Baghdad city conditions.The results showed that;approximately a steady temperature of hot drying air was obtained during relatively low ambient temperatures when the dryer was incorporated with multiple PCMs.The drying time of the product sample for the natural,forced convection without PCMs and forced with PCMs was 87,72 and 47 h,respectively.The higher performance of the dryer was for the forced convection with PCMs.The reduction percentage in drying time was about 17.2%and 46%for the forced convection without and with PCMs respectively compared with natural convection.The average drying rate for the natural,forced without PCMs and forced convection with PCMs was 0.0093,0.0135 and 0.0172 kg/h,respectively.The enhancement in thermal efficiency of the solar collector and drying chamber with multiple PCMs was 43%and 25.5%,respectively,compared with a typical solar dryer.

双折线卷筒上钢丝绳卷绕状态的力学分析

钢丝绳偏角直接影响钢丝绳在双折线卷筒上的卷绕整齐性。因此本文以双折线卷筒的钢丝绳截面单元微元体为分析对象,建立了双折线卷筒在均速转动条件下钢丝绳卷绕状态的力学模型。通过该力学模型分析表明,卷筒均速转动下钢丝绳后偏时钢丝绳随着钢丝绳偏角增大受到挤压力增大,但“骑绳”现象很难发生;当钢丝绳前偏时钢丝绳偏角超过绳槽螺旋角时“跳绳”现象可能会发生,并且钢丝绳偏角越大“跳绳”越容易发生。其次,通过所建的力学模型对工程实例进行了计算分析;结果表明,平行线绳槽段的钢丝绳偏角是决定“跳绳”发生的关键,同时钢丝绳张力越大越容易发生“跳绳”。本文建立的双折线卷筒力学分析模型可以为提升绞车的参数设计和钢丝绳的选择提供了的理论依据。

对辊式干辣椒脱帽装置设计与试验

针对辣椒机械化脱帽存在的辣椒损伤大、辣椒蒂去除不净等问题,结合辣椒物理力学特性及机械化加工要求,设计了一种对辊式干辣椒脱帽装置。该装置关键部件包括滚筒、脱帽辊和筛网3部分,采用旋转滚筒和回转辊轴的方式实现辣椒脱帽。通过对脱帽装置工作过程分析,确定了去除辣椒蒂的临界条件。借助辣椒受力及运动特征研究,确定了滚筒及脱帽辊的关键参数。滚筒直径为1.8 m、长度为6.0 m、转速为28.83 r/min,脱帽辊的直径为36.0 mm、间隙为0.5 mm、转速为134.21 r/min。通过对筛面利用系数分析,确定了筛分效率较高的方形筛网,且筛面利用系数为60.5%。通过Design-Expert 12软件进行试验设计及数据处理,明确了滚筒转速、脱帽辊转速对损伤率、脱净率的影响规律,并确定了较优参数组合,为辣椒机械化加工技术及装备研发提供理论依据。试验结果表明,该装置损伤率为0.6%,脱净率为98.8%,符合行业标准且满足辣椒机械加工要求。

双滚筒式收后地表残膜回收机设计与试验

针对残膜回收机存在的拾净率低、含杂率高等问题,该研究设计了一种双滚筒式残膜回收机,适用于秋收后地表残膜回收,采用机械拾膜、气力与机械协同脱膜方式完成作业过程。对捡膜和脱膜过程进行动力学分析,确定捡膜装置和脱膜装置的关键结构参数以及工作参数范围,根据滚轮中心运动轨迹设计并优化正反向凸轮轨道,得到凸轮结构参数,获得捡膜装置不漏捡的条件。运用气流特性分析软件模拟脱膜装置内部流场,分析得出气流运动形成的“O”形旋流利于残膜与杂质的分离。以机具前进速度、捡膜滚筒转速和脱膜滚筒转速为试验因素,残膜拾净率及回收混合物含杂率为试验指标,进行单因素试验,得到响应面试验水平的较优区间,并进行响应面试验,得出较优工作参数为机具前进速度6.72 km/h,捡膜滚筒转速56.70 r/min,脱膜滚筒转速569.78 r/min。田间试验结果表明,机具前进速度6.7 km/h、捡膜滚筒转速57 r/min、脱膜滚筒转速570 r/min时,平均残膜拾净率为86.1%,平均回收混合物含杂率为39.2%;相较于已有回收机的残膜拾净率(85.03%)提高了1.07个百分点,各项指标满足收后地表残膜回收要求。

滚筒参数对采煤机装煤效率的影响

基于离散元理论,结合颗粒位移方式以及颗粒间接触本构建立了中厚煤层双滚筒采煤机仿真模型,通过模拟得出采煤机滚筒转速、转向、牵引速度以及叶片螺旋升角等因素与装煤效率的关系,进一步分析其影响规律及原因得到各影响因素间的最佳组合,为今后双滚筒采煤机装煤效率的改进与研究奠定了基础。

Analysis of Steel Slag Treatment Process and Comprehensive Utilization

As a by-product of steel enterprises,steel slag has a huge output and is rich in valuable minerals,but its comprehensive utilization rate is very low.The article mainly introduces the hot splashing method,hot sealing method,and drum method for the treatment of steel slag outside the furnace,and compares and analyzes the advantages and disadvantages of the production operation process and steel slag treatment process.At the same time,it also introduces the residual slag+double slag process and gasification dephosphorization slag circulation steelmaking technology for steel slag treatment inside the furnace,providing direction for steel enterprises to clean and comprehensively utilize steel slag.

综采面双滚筒采煤机的常见故障及其处理措施

结合某矿工作面的回采看,所应用的MG300/700-WD采煤机经常出现运转故障问题,主要涉及到液压系统调高失灵、截割部油温过高、采煤机牵引力不足、采煤机摇臂升降失效和采煤机变频器故障等方面,使回采面作业质量受到影响。为此,先阐述回采工程案例,然后分析MG300/700型采煤机的结构及原理,最后基于常见问题进行针对性的故障处理,以期望可以有效控制采煤机的故障率,提高采煤机的运转质量。

刮板输送机配套参数对采煤机装煤效率的影响

采煤机滚筒在开采中起截煤与装煤的作用,随着对采煤机功率的深入研究,目前采煤机滚筒的截煤能力已基本满足要求,但装煤效率方面还存在很多问题,中厚煤层方面装煤效率的研究更是少之又少。基于离散元理论,结合颗粒位移方式以及颗粒间接触本构建立了中厚煤层双滚筒采煤机仿真模型,通过模拟计算出采煤机刮板输送机挡煤板高度、中部槽宽度、中部槽与煤壁水平距离等因素对装煤效率的影响曲线,并进一步分析其影响原因,为今后双滚筒采煤机装煤效率的改进与研究奠定了基础。

双钢轮压路机动力舱隔声性能优化及消音器优化分析

本文旨在提高双钢轮压路机动力舱的隔声性能,针对特定频段内的噪声问题,提出了改进方案。采用间接边界元法对动力舱通风结构进行了仿真,设计了新型的双层通风结构,有效提高了目标频段内的隔声性能。对于消音器通过有限元法和遗传算法优化其结构,实现了在低频范围内的传递损失提升,同时略微降低了高频范围的传递损失。优化后的消声器结构简化,且保留的吸声材料腔室有助于提升高频消声性能。研究结果表明,综合优化策略能够有效改善动力舱的整体隔声效果,为压路机噪声控制提供了科学依据。

综采面双滚筒采煤机的常见故障与处理分析

为进一步提升双滚筒采煤机的运行质量,结合实际案例,分别对双滚筒采煤机运行时常见的截割部齿轮损坏故障、振动故障和液压调高系统失准故障3种情况进行初步分析,并根据分析结果,分别提出了针对性的解决措施。结果显示,应用以上解决措施后,有效解决了相应的问题,证明该研究具有一定实际应用价值,能为今后的相关工作提供一定参考。

卧螺离心机双锥角转鼓结构的有限元分析

文中利用ANSYS有限元软件建立了大型卧螺离心机双锥角转鼓的二维有限元模型 ,对其在正常工作状态下的整体结构进行了静力分析 ,得到了转鼓的径向、轴向变形和应力分布及最大应力点 ,结果表明双锥角转鼓的强度和刚度均满足要求 。

联合作业打瓜取籽机关键部件的设计与研究

打瓜是新疆地区的主要经济作物,其生产过程机械化程度低,严重制约了新疆大田生产的发展。为此,拟定了一种将打瓜破碎和分离清选的设计方案,阐述了破碎装置的工作原理、结构组成和结构尺寸的设计。通过取样试验测得打瓜样本的平均值,设计了对辊破碎机构的间隙极限值,间隙极限值分别为dmax=1 0 0 mm,dmin=2 0 mm。阐述了籽瓤分离装置的工作过程、结构布局和结构尺寸的设计,设计了一种双滚筒式分离清选装置。通过取样试验测得新疆地区打瓜籽的三轴尺寸样本平均值,确定了内外筛网孔的尺寸,内外尺寸分别为20mm≤D1≤25 mm,5 mm≤D2≤8 mm。通过对破碎、分离清选装置的设计,提高了打瓜取籽机的工作效率,降低了破损率,对大面积种植模式,尤其是新疆地区具有促进作用。

基于双滚筒优化模型的采煤机运动参数优化

目前大多数研究采煤机运动参数优化问题时,普遍采用仅包含1个牵引速度和1个滚筒转速的单滚筒优化模型,但由于双滚筒采煤机两侧滚筒受力情况及截割状态不完全相同,由单滚筒模型所得结果并不完全适用于双滚筒采煤机。作者以某型双滚筒采煤机为研究对象,以牵引速度和左、右滚筒转速3个运动参数作为设计变量,建立了双滚筒运动参数优化模型;利用遗传算法(GA)对双滚筒采煤机运动参数进行优化,并将最优参数下的截割性能与工业参数下的截割性能进行了对比,结果表明最优运动参数下的截割性能更优;对单、双滚筒两种优化模型下的优化结果进行了对比分析,结果显示双滚筒模型优化后的综合截割性能较单滚筒模型优化提高了16.35%,表明双滚筒优化模型下的截割表现更优。

中国与外国双钢轮振动压路机的主要差距

对国内外双钢轮振动压路机进行了对比试验和性能检测。结果表明:中国产双钢轮振动压路机与国外同类产品相比的主要差距是振幅沿振动轮横向分布均匀性超过5%、起步和停车时的瞬时功率超过额定值,减振与降噪指标不能完全达到国标要求,并导致两者工作可靠性和作业质量的差异。指出双钢轮振动压路机为大惯量循环作业式机械,起步和停车时间短,应错开起步和起振时功率峰值的发生时间;振幅和压实均匀性是对振动压路机作业质量的基本要求,应使振动轮的激振力通过其质心,减振和噪声必须符合环保要求。

1000kV交流同塔双回线路伞形塔与鼓型塔比较

为对特高压交流输电线路建设提供技术基础,比较了劈腿式伞形塔和收腰式伞形塔的区别,指出后者防雷性能好、杆塔质量小、工频场强稍小,收腰式伞形塔的性能优于劈腿式伞形塔。选择采用劈腿式伞形塔,还是收腰式伞形塔,与导线水平位移距离的要求值大小有关。特高压交流同塔双回线路导线之间的垂直距离达21 m,从脱冰跳跃的计算和试验结果论证了特高压交流同塔双回线路导线间不需要特别提出水平位移距离要求,收腰式伞形塔可以满足脱冰跳跃要求。双回线路的中相导线是同名相,中相导线之间的距离稍有差异,对电磁环境影响很小。通过线路的计算表明,特高压同塔双回收腰式伞形塔线路可以满足电磁环境标准要求,与鼓型塔的基本相同。在防雷性能上收腰式伞形塔明显优于鼓型塔。建议我国特高压交流同塔双回线路宜选择收腰式伞形塔。

基于双流体模型的简易化两相搅拌流场数值模拟

基于双流体模型对混凝土搅拌运输车搅拌筒内搅拌介质进行了简易化的数值模拟,为搅拌筒参数优劣评定提供了有效的参照模型。即将混凝土搅拌运输车搅拌筒中搅拌介质(石子与泥浆)的流固多相处理成密度不同且互相贯穿的介质,以搅拌筒和搅拌叶片为动态边界条件,在流体有限元理论下,实现了基于搅拌筒设计参数变化的简易化多相流场数值模拟。从而在混凝土搅拌运输车搅拌筒数字化设计过程中,在对参数的优劣(减小搅拌介质的离析度和提高搅拌筒的出料速度等)评定时,提供了定量化、可视化的参照模型。