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研究清楚离心机转鼓参数与转鼓应力、变形的关系,是保证其在安全的工作状态下,对转鼓进行参数优化的基础。在诸多参数中,对转鼓3个主要参数:转速、转鼓壁厚和液池深度进行分析研究。结果表明,各种载荷下转鼓的最大径向位移均与转速的二次方成比例,且随着转速的增加,会导致转鼓径向变形增大;正常工况(Fw+Pc)下的应力SINT(SINT为第三强度理论的等效应力)最大值随着转鼓壁厚的减小而增大,但增大的幅度较小;转鼓的总径向位移最大值和物料离心压力引起的径向位移的最大值均随着液池深度的增加而增大,但增长速度缓慢;转鼓自身质量离心力产生的径向位移与转鼓的液池深度无关。这些数据将为己有的卧螺离心机的改造优化和工程实际应用提供设计依据。 相似文献
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通过现场检查、试样检测和应力分析,确定转鼓壁厚严重减薄是该离心机事故的主要原因,而转鼓壁厚减薄的主要原因是糖浆液中的微晶粒磨损和冲蚀转鼓。建议对使用10年以上的离心机转鼓的壁厚、焊缝、硬度等需进行安全检测。 相似文献
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矿用卧螺离心机能够极大地提高煤泥水混合物的分离效果,减少煤炭资源的浪费并降低其污染。然而,卧螺离心机转鼓锥段的锥角大小能够直接影响煤泥的含湿率,所以转鼓锥段锥角的参数大小对离心机进行煤泥分离有着至关重要的作用。通过使用FLUENT软件采用仿真试验的方法研究了转鼓锥角的变化情况对卧螺离心机固液分离的影响。结果表明:根据目前所已有的矿用卧螺离心机中的转鼓锥角,选取不同的转鼓半锥角(3°,5°,7°,9°,11°,13°),对不同转鼓半锥角中矿用卧螺离心机所的分离性能进行了模拟研究,同时结合锥段处转鼓的截面压力变化规律,最终找出最佳的卧螺离心机转鼓半锥角,对其进行试验验证。结果表明矿用LW800卧螺离心机的转鼓锥角为7°时,比其他角度更能够有明显的分离效果,分离出的泥浆干稠,水液体清澈。即矿用LW800卧螺离心机的最佳转鼓锥角为7°。 相似文献
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基于沉降离心机的结构及工作原理,以LW800沉降离心机为例,结合沉降离心机在洗煤厂中的应用情况,以排出口物料含水量为指标,从转鼓转速、转鼓锥角和螺距三个方面探讨了沉降离心机工作效果.分析表明:将转速设定为2000 r/min可在较低的能耗下实现含水量大幅度降低;为进一步减少物料的的水分含量,可将水平螺旋沉降离心机的转鼓锥角增加1°~2°;原来的螺距尺寸(208 mm)合理,在保持良好输送能力的同时可确保排出口物料具有较低的水分含量. 相似文献
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本文定性地分析了卧螺离心机的沉渣输送与其转鼓的锥角β、螺旋推料器叶片的倾角6、叶片的螺距、液池半径γ及差转速△n之间的关系,阐述了改善卧螺离心机输渣条件的设计思想。 相似文献
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卧螺离心机转鼓锥角结构设计及参数优化 总被引:4,自引:0,他引:4
转鼓锥角是卧螺离心机设计中最为重要的一个参数,它的大小对于沉渣含湿率有重要的影响.目前只能根据试验数据选择锥角参数,不仅费时耗力,而且由于试验误差而无法找到最佳的角度.结合建筑泥水的特点,采用FLUENT软件研究转鼓锥段固液分离的规律;分别对锥角为6°、7.5°、9.5°、12°进行建模及三维网格划分,模拟分析不同锥角条件下卧螺离心机的转鼓速度场;设计出在一定程度上能够满足建筑泥水处理的大直径卧螺离心机双锥角转鼓.通过仿真试验表明,当锥角为9.5°时,最大沉积层厚度更接近于分料口,为最优的锥角参数;设计的转鼓双锥角结构的水泥分离液含湿率及处理率具有更高的处理量和更低的含湿率,其结构的整体性能得到很大的提高,增加了卧螺离心机的工作效率. 相似文献
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提出一种斜线槽上游泵送机械密封,运用正交试验法设计上游泵送机械密封试验方案,基于Fluent软件进行数值模拟试验,分析各个试验参数对密封端面开启力和泄漏量的影响。结果表明:在试验参数的取值范围内,对开启力有显著影响的因素是槽数、径向夹角、槽深、液膜厚度、转速和压差,具体表现为开启力随着径向夹角、槽深、液膜厚度、转速和进出口压差的增大呈上升趋势,随着槽数的增多呈下降趋势;对泄漏量有显著影响的因素是槽深、槽宽比、液膜厚度、转速和压差,具体表现为泄漏量槽宽比、液膜厚度、转速和进出口压差的增大呈上升趋势,随着槽数的增多而呈下降趋势。依据正交试验分析结果,提出初步优化的密封端面结构参数。 相似文献
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采用LS-DYNA软件对锥倾角0°~40°、壁厚1 ~2.5 mm的A6061圆锥管进行轴向压缩仿真,研究锥倾角和壁厚对圆锥管吸能特性和变形规律的影响;基于Mamalis圆锥管瞬时载荷压溃模型,提出大范围锥倾角(15°~40°)瞬时载荷修正公式。研究结果表明:变形模式的临界角为15°,当锥倾角小于等于15°时,变形模式为堆叠模式,当锥倾角大于15°时,变形模式转变为嵌套模式;平均载荷与比吸能均随着锥倾角的增大缓慢减小,而初始峰值载荷则大幅度减小;随着壁厚增大,压溃模式由钻石模式转变为环形对称模式,平均载荷、初始峰值载荷和比吸能均增大。基于仿真结果,采用皮尔逊相关系数分析法修正了Mamalis瞬时载荷公式,修正值与仿真值的最大误差小于10%,通过试验验证了修正公式的准确性。修正公式为揭示大范围锥倾角薄壁管压溃机理提供了理论依据。 相似文献
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Xiaoxiao Chen Jun Zhao Yueen Li Shiguo Han Qingyuan Cao Anhai Li 《The International Journal of Advanced Manufacturing Technology》2012,59(9-12):885-898
The generation mechanism of machining-induced residual stresses is a complex nonlinear and thermal–mechanical coupling problem. The cutting forces and cutting temperature produced in machining process must be considered simultaneously. The influence of cutter orientation and feed per tooth on the cutting speed, cutting forces, cutting temperature, and residual stresses is discussed in the present study. Effective cutting speed in accordance with the inclination angle in feed direction is analyzed. The cutting forces are gained by milling experiment, and the cutting temperature is obtained by finite element method. Moreover, the influence of the effective cutting speed on the cutting forces and cutting temperature is stated, and the relationship among the cutting forces, cutting temperature, and residual stresses is discussed. The experimental and numerical methods are both adopted in this study to give a better understanding of the milling process. After analysis of the phenomenon, several conclusions are made. The inclination angle in feed direction affects the effective cutting speed, and then the cutting forces, cutting temperature, and residual stresses are affected. Priority selection of inclination angle in feed direction is suggested from 5° to 30° in order to reduce the cutting forces. The overall trend of the workpiece temperature presents the parabolic shape, while the chip temperature increases with the increasing inclination angle in feed direction. Residual stress in feed direction almost increases with the increasing feed per tooth, which is not obvious in the general scope of the feed rate. The inclination angle of 5° and 15° is the priority in order to produce residual compressive stresses in cross feed direction. 相似文献
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The residual stress distribution in the surface region of workpieces of a bearing bronze that is machined under unlubricated, orthogonal conditions is determined using a deflection etching technique. The residual stress at the surface is low (compressive) and increases with an increase in depth beneath the machined surface to a maximum (tensile) then decreases continuously with a further increase in depth eventually becoming vanishingly small. The peak residual stress and depth of the stressed region increase with an increase in cutting speed, an increase in feed rate and an increase in tool rake angle but are independent of tool wear land length. The results of the investigation are interpreted qualitatively in terms of the type of chip produced and the variation of the thickness of the deformed surface region with cutting conditions. 相似文献
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为了分析圆柱滚子式三叉杆万向联轴器圆柱滚子与滑块槽之间的脂润滑状况,基于Ostwald模型建立线接触热弹流脂润滑数值计算模型。结合联轴器的稳态工况参数,采用多重网格法、逐列扫描法对润滑油膜压力、膜厚和平均温升求解;探究不同输入轴与输出轴轴线夹角、不同输入轴回转半径、不同圆柱滚子半径、不同初始黏度和不同流变指数对联轴器热弹流脂润滑特性的影响。研究结果表明:减小输入轴与输出轴轴线夹角、减小输入轴回转半径、减小润滑脂初始黏度有利于降低二次压力峰和平均温升,但膜厚减小;增大圆柱滚子半径有利于降低二次压力峰和平均温升,增大膜厚;增大流变指数,有利于增大膜厚,降低温升,但二次压力峰增大。因此,根据实际工况选择较小回转半径,适当减小轴线夹角和增大圆柱滚子半径,适当减小润滑脂初始黏度和增大流变指数,均有利于改善联轴器润滑特性。 相似文献
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Illés Dudás Sándor Bodzás Zoltán Mándy 《The International Journal of Advanced Manufacturing Technology》2013,69(5-8):1025-1031
During the classical manufacturing process of conical thread surfaces with lathe center displacement, the worm shaft is driven with the help of the driving pin through the lathe fork. As a result of the shifting of the worm shaft by half cone angle, the path curve of the driving pin will be an ellipse path instead of a circle on the perpendicular plane to axis. The peripheral speed of the spindle is constant, but due to the ellipse path, the radius is constantly changing as a function of time. That is why the angular velocity and the angular rotation are also changing, and these cause pitch fluctuation during the manufacturing process of conical worms. During the manufacturing process, we have examined pitch errors which are caused by angular velocity fluctuation and we have also determined the geometrical shaping of the driving pin by which errors of the pitch can be eliminated. 相似文献
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Nowadays incremental forming is more popular because of its flexibility and cost saving. However, no engineering data is available for manufacturers for forming simple shapes like a frustum by incremental forming, and either expensive experimental tests or finite element analysis (FEA) should be employed to determine the depth of a frustum considering: thickness, material, cone diameter, wall angle, feed rate, tool diameter, etc. In this study, finite element technique, confirmed by experimental study, was employed for developing applicable curves for determining the depth of frustums made from 304 stainless steel (SS304) sheet with various cone angles, thicknesses from 0.3 to 1 mm and major diameters from 50 to 200 mm using incremental forming. Using these curves, the frustum angle and its depth knowing its thickness and major diameter can be predicted. The effects of feed rate, vertical pitch and tool diameter on frustum depth and surface quality were also addressed in this study. 相似文献
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Jing Shi Yixin Shi C. Richard Liu 《The International Journal of Advanced Manufacturing Technology》2011,54(1-4):161-171
In this paper, a molecular dynamic simulation study was performed to study 3D single-point turning of a monocrystalline copper workpiece with rigid diamond tools at nanometric scale. Morse potential energy function was applied to model the copper/diamond and copper/copper interactions. Two-groove cutting was employed to simulate the surface creation in 3D single-point turning operations. Multiple machining conditions were investigated by considering the effects of rake angle, machining speed, depth of cut, and feed rate. Not surprisingly, in machining both grooves, the tool forces increase with the increase of feed rate and depth of cut, as well as the use of a smaller rake angle. These general observations are consistent with the conventional metal machining at longer length scales. On the other hand, it was found that the increase of machining speed also significantly causes the rise of tool forces. Moreover, the stress and instantaneous temperature distributions in the workpiece were analyzed. It was discovered that for all conditions investigated, the equivalent stress and temperature distributions actually resemble these reported for conventional machining. All cutting parameters affect the magnitude and distribution of stresses to a certain extent, while the machining speed appears to be the dominant factor for the machining temperature. 相似文献
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Since the cylindrical and circular crested weirs are economical and easily made compared to some other weirs, they can be used to measure the flow velocity, the water discharge and flow surface control structures in the canals and reservoirs. In this paper, the hydraulic properties of the cylindrical and circular crested weirs, such as the discharge coefficient, the depth on the crest of the weir and the energy loss in 18 laboratory models categorized in 5 categories have been investigated. The results of the experiments indicated that in both the cylindrical and circular crested weirs by increasing the total partial head, the discharge coefficient increases and any changes in the upstream wall slope has no effect on the discharge coefficient. Also, the partial energy loss more occurs in the cylindrical weirs than the half shaped cylindrical weirs and by increasing the downstream inclination angle, the partial energy loss increases subsequently. The partial flow depth on the crest of both the cylindrical and half shaped cylindrical weirs is equal to 0.7 and by increasing of the upstream inclination angle, the partial flow depth on the crest in the values greater than 0.6, increases slightly and the downstream inclination angle changes of the partial flow depth has no effect on the crest. 相似文献