人人文库网 > 图纸下载 > 毕业设计 > 细石混凝土搅拌机设计【10张图纸】【优秀】

限位销.dwg

细石混凝土搅拌机设计【10张图纸】【优秀】

资源目录

细石混凝土搅拌机设计【10张图纸】【优秀】.rar

细石混凝土搅拌机设计说明书.doc---(点击预览)

外文翻译--混合性能单轴构件式搅拌机英文版.pdf---(点击预览)

外文翻译--混合性能单轴构件式搅拌机中文版.doc---(点击预览)

减速装置.dwg---(点击预览)

主轴.dwg---(点击预览)

压缩包内文档预览：

编号：422391 类型：共享资源大小：3.70MB 格式：RAR 上传时间：2015-04-02 上传人：上*** IP属地：江苏

39
积分

版权申诉 word格式文档无特别注明外均可编辑修改；预览文档经过压缩，下载后原文更清晰！ 立即下载

关键词：: 混凝土搅拌机设计混凝土搅拌机图纸细石混凝土搅拌机

资源描述：

细石混凝土搅拌机设计

45页 14000字数+说明书+外文翻译+10张CAD图纸【详情如下】

主轴.dwg

减速装置.dwg

外文翻译--混合性能单轴构件式搅拌机中文版.doc

外文翻译--混合性能单轴构件式搅拌机英文版.pdf

搅拌机装配图.dwg

搅拌杆.dwg

料筒.dwg

机架.dwg

细石混凝土搅拌机设计说明书.doc

说明书.doc

轴承座.dwg

轴承座端盖.dwg

限位架.dwg

限位销.dwg

QQ截图20140210171635.gif

机架.gif

减速装置.gif

搅拌杆.gif

料筒.gif

全部文件.gif

细石混凝土搅拌机设计.gif

限位架.gif

限位销.gif

轴承座.gif

轴承座端盖.gif

主轴.gif

摘要I

AbstractII

1 绪论1

1.1 混凝土搅拌机械1

1.2 混凝土搅拌机结构和工作原理3

2传动部分设计4

2.1电动机的选择4

2.2传动比的分配7

2.3计算传动装置的运动和动力参数8

2.4第一级齿轮传动的设计10

2.4.1材料的选择10

2.4.2确定齿轮主要尺寸13

2.5第二级齿轮传动的设计16

2.5.1材料的选择16

2.5.2确定齿轮主要尺寸18

2.6减速器的润滑和密封21

2.6.1传动的润滑21

2.6.2轴承润滑22

2.6.3密封装置22

3 搅拌机的工作原理23

3.1 搅拌机的结构组成23

3.1.1搅拌机料筒24

3.1.2搅拌机叶片24

3.1.3搅拌机轴承24

3.1.4搅拌机联轴器27

3.1.5搅拌机轴28

3.1.6搅拌机支架34

3.2 工作过程35

3.3电路控制36

4.1搅拌机使用的注意事项37

4.2搅拌机的日常保养37

结论39

致谢40

参考文献41

1 绪论

1.1 混凝土搅拌机械

混凝土施工机械的发展状况是影响建筑工程施工机械化程度的重要因素之一。因为建筑技术与建筑工程的现代化已经使建筑物的基础、梁、柱、板等主要构件几乎都是混凝土浇筑而成的．如果工程中所用的大量混凝土，其生产过程中的各道工序(即贮料、装料、配料、搅拌、运输、浇筑和振捣)都采用人工操作，则不仅需要大量的劳动力，而且劳动强度高、效率低、混凝土的质量差。为此，必须十分重视混凝土施工机械的发展和应用，并作为提高建筑施工机械化程度的主要技术措施之一。当前，我国建筑工程中混凝土的加工虽已基本机械化，但分散件很强，尚不能走向较高程度的工业化，商品混凝土应用的程度还很小。今后一段时间内，要把注意力放在混凝土施工地机械化体系的配套上，使之更加完善。

混凝土搅拌机是将一定配合比的水泥(胶结材料)、砂、石(骨料)和水(有时还加入一些混合材料)拌和成匀质混凝土的机械。同人工拌和混凝土相比，混凝土搅拌机具有生产率高，拌和质量好，减轻工人劳功强度等优点，如今它是建筑施工现场、混凝土构件厂及商品混凝土供应站生产混凝土的重要机械设备之一。

混凝土搅拌机按搅拌混凝土的原理来分有自落式和强制式两种。

自落式混凝土搅拌机工作机构是筒体，沿筒内壁圆周安装若干搅拌叶片。工作时，将物料投入搅拌筒内，筒体绕其自身轴旋转，靠搅拌筒的旋转，由筒内的搅拌叶片将物料推到一定的高度后，物料靠自重坠落下来，反复对物料进行搅拌而加工成匀质混凝土。这种搅拌机特点是搅拌强度不大，效率低，只适合加工普通塑性混凝土，对骨料的粒径要求不严格，广泛地应用于各种中小型建筑工地。是现在建筑行业中应用较为广泛的一种混凝土搅拌机。

强制式混凝土搅拌机的搅拌机构是水平式设置在筒内的搅拌轴，轴上安装搅拌叶片，工作时，强制式混凝土搅拌机的搅拌筒固定不动，是由筒内转轴的带动叶片旋转来对物料进行强制式的剪切，挤压、翻转的强制搅拌作用，使拌合料在剧烈的相对运动中达到均匀拌和。这种搅拌机搅拌质量好，效率高，适合加工普通塑性和半硬性的混凝土。由于受构造上的限制，对粗骨料粒径的要求较为严格，施工现场的混凝土搅拌站和混凝土预拌工厂的搅拌楼中使用的搅拌机均系此种类型。

混凝土搅拌机，按其外形又可分为鼓形、锥形和盘形二种；按所用动力装置不同又分为电动式和内燃式两种；由搅拌量的不同，又将搅拌机分成多种容量型号，目前世界上的混凝上搅拌机已有200种以上。我国混凝土搅拌机的容量、规格的发展也很迅速，容量仅在3000L以下的就合11种之多，它们是；50，100，150、200，250，350，500，750，1000，1500和3000L这些搅拌机都同属周期作业式，随着混凝土施工工艺的发展和对搅拌机要求的提高，必将很快推出各种新型的混凝土搅拌机械。

根据搅拌机搅拌筒容量参数的小同，又常把混凝土搅拌机划分为大型(出科容量为1—3)、中型(出料容量为0.35—0．75)和小型(出料容量为0.5一0.25)三种。

我国混凝土搅拌机的生产业已定型，并自成系列，其代号和主要技术参数的意义：

J——搅拌机：

G——鼓形自治式混凝土搅拌机；

Z——锥形反转出料式混凝土搅拌机；

F——锥形顿翻出料式混凝1：搅拌机；

D——单卧轴强制式混凝土搅拌机；

JG250型混凝土搅拌机——表示鼓形自落式混凝土搅拌机，电动机驱动，出料容量并经捣实后的混凝土体积为250L。

混凝土搅拌机其主要组成部分有：

搅拌机构.它是混凝土搅拌机的主要工作机构，由搅拌筒、搅拌叶片等组成。

传动装置它是向搅拌机各工作机构传递力和速度的系统。—般有由带条、摩擦轮、齿轮,、链轮和轴等传动元件组成的机械传动系统和由液压元件组成的液压传动系统两大类。

内容简介：: 混合性能单轴构件式搅拌机摘要对许多研究人员来说参与混合动力研究仍然是一个感兴趣的主题，然而理论不发达，大部分设计都建立在经验基础上。在许多行业,包括药品,大部分混合机器是“翻滚搅拌机”。滚筒中有空容器,部分装满了材料。一些常见的例子包括水平鼓v形搅拌机、双筒搅拌机、果汁机、书本搅拌机。在所有这些搅拌机而均匀旋转方向的块,通常透过一个对流混合过程、混合横向(轴向)方向驱动,然而比较慢。在本文中,我们实验研究了新翻滚旋转搅拌机，它对水平轴(滚运动)和中央对称（旋转运动)进行了详细的研究。混合粉末和性能的关键影响的基本参数包括搅拌器几何速度、填充水平、加载模式以及轴旋转。在这部作品中乙酰氨基酚是用作原料及常用的赋形剂和乳糖微晶纤维素等。混合后试样后利用近红外光谱分析获取标准函数以确定作曲的分布。结果表明,在轴的旋转下几乎所有粉末均匀交融。1. 简介粒子混合是必不可少的步骤,在各种应用中跨越了陶瓷、食品、玻璃、冶金、聚合物和医药行业。尽管历史悠久的干固体混合(或者也许因为它),比较所知甚少3。一种常见的批量工业混合机是将搅拌器打开,将颗粒流因重力结合而后旋转。虽然该搅拌器是一个很常见用于混合，隔离的设备,但这些混合设备很大程度上只是基于实证的方法。滚筒式烘干机虽然作为最普遍的批量搅拌机应用于各行各业中,而使用的人同时也希望能找到其它实施烘干机、镀膜机、磨坊机、遭粒机4-8，而新型材料在旋转鼓中的混合已经广泛地开始研究了9、10,然而这些材料的系统粘性还不完全被人所理解。很少有人了解基本参数的影响,如搅拌器几何、速度、填充水平、加载模式和轴的旋转粘性对粉混合性能上的要求。然而传统滚筒式烘干机,它们都有一个重要特点，就是绕着水平轴,:当均匀旋转方向的块透过一个对流混合过程、混合横向(轴向)方向分散,致使驱动过程通常较慢。在本文中,我们实验研究了水平轴(滚运动)和中央对称轴（旋转运动)对新翻滚旋转搅拌机的影响,在混和所需时间、加载模式和轴的旋转中对混合矩阵的自然流畅的性能的要求。其中材料包括微晶纤维、乳糖和乙酰氨基酚。我们使用近红外光谱分析检测方法获取大量的样本来跟踪并描述混合均匀性对乙酰氨基酚进化的影响。材料选择和研究方法在后面有具体介绍,仿真在第三节,其次是结论和建议,第四节给出了总结。2. 材料和方法在研究中使用的材料都列在表1,连同它们的大小和形态。对乙酰氨基酚是混合了常用的赋形剂来作为示踪程度的评估以及实现均匀转数的功能。而乙酰氨基酚和常作为药用辅料的乳糖微晶纤维素的药物通常混合起来用于广泛的研究。简单的来说,他们的SEM分析不包括这些,但也可以发现,在药用辅料中也会有所研究。2. 1近红外光谱分析对均匀的乙酰氨基酚用近红外光谱进行量化分析，校准曲线并构建35%的粉末混合物的(平均)，微晶纤维素,62%的乳糖和乙酰氨基酚的图像。近红外光谱技术可以作为很有用的工具来描述乙酰氨基酚。样品制备比率的保持使微晶纤维素随机减少缺陷的影响而赋形剂的真正融合提高了实验结果的精度。快速内容分析仪仪器是用近红外系统和视觉软件(版本2.1)共同来分析的。其中将1克重的样品混合，而在台北使用平衡的精确度0.01毫克，在光谱扫描范围内的收集1116-2482的混合模式，开发利用二阶微分数学预处理,并利用偏最小二乘(PLS)来校正模型，最大限度地减少粒度的影响。如图1，对压荷载之间的预测值和最后的校准。2.2用于该研究中的搅拌机:室内单轴搅拌机(搅拌器1),双轴搅拌器(搅拌器2)由于容量为30L的圆柱状搅拌器1广泛的使用,我将它选做为一个参考搅拌器。图2,这台有圆形截面和底部为椭圆的果汁机，它有一个很好的隔板,并有个可移动的盖子，但在这项研究中所有的实验而不使用隔板。新开发的容量为40L搅拌器2提供基线接收机来评价混合性能,而用圆柱体是为了确定双轴对混合旋转性能的影响。在图2(b)中搅拌器显示两个轴旋转，旋转的相对运动速度是中央对称轴绕水平轴向速率的一半。2. 3实验方法在实验中采用两种类型的初始粉加载:自上而下加载和侧面加载,如图3。为了避免结块，对乙酰氨基酚被放入搅拌器中通过,并在筛网选择35个样本参考点。为了描述该过程,用混合槽提取搅拌机样品的采样方法选取7.5,15,30,60和120格点。仔细的进行筛选,并在每点提取的样品放在搅拌器中来减少振动。约7次采样,并从每个点开始共设5个被用于采样的时间,最后将总体35个采样绘制如图4。该实验研究计划如下:填补等级:搅拌器1-60%填补等级:搅拌器2-60%,70%,80%加载方式:搅拌器1 - 两侧面载荷、自上而下载入加载方式:搅拌器2 - 两侧面载荷、自上而下载入速度:搅拌机1每分钟20,25转速度:搅拌器2 -旋转: 每分钟转速15/7.5,每分钟转速30/15采样时间:搅拌机第1，2-7.5 30,60,120转3. 结果均匀性指数是相对C浓度的每个样本,的平均浓度样品和总数是在给定样品进行采样时间的n。相对标准偏差=，而S=我们之前有研究填补水平的影响,所有将搅拌器打开,将填补的材料扔到双锥搅拌器中进行搅拌11。所有上述搅拌机只有一个轴的旋转,因此本研究的目的在于探究混合的双轴的影响。为了避免重复,本搅拌器1不进行填补水平的研究。根据在以前的研究中使用MgSt作为示踪表明的结果来看,室内单轴搅拌机混合下来的填满水平大大超过70%。此外,也可以假定对乙酰氨基酚类的研究结果似在此前的研究中获得11,13,作为一个单一的轴矩形本搅拌器11,此结果表明,即使在几百次改革中所实现的均匀的80%填补水平仍然很差。检查填补水平是否影响双轴搅拌机得实验,我们分别进行了自上而下对搅拌器进行加载的格局，即转速为每分钟15和7.5。从检查填充水平的角度来看,对填满水平在60%、70%和80%以上的采样,否则样品选取后面每分钟30、60和120转的。典型的结果显示在图5中,这表明相对的数量较集中。而此数据曲线被大多资料认为是一个快速腐朽的地区。由于曲线的斜率在这个地区,所有这些坐标被用于定义混合率。然后水平曲线表明了一个最大均匀度的是可以实现的。类似于先前其他翻滚搅拌机的研究，我们观察到混合性能所产生得负面影响,因此通过提高填补水平来减小影响。在图5中,曲线为80%的填补相比60%和70%填补更糟糕;可以看到填充水平越高,曲线更慢衰减,这象徵一个较慢的混合过程。然而效果不明显,所以该种现象(相同的渐近混合均匀性)是本国需要提高填补的水平的关键。其次,研究比较搅拌机1一个轴的旋转和双转轴搅拌机2对转速的影响。实验是进行自上而下和两侧面搅拌机载入。实验以60%进行填充水平和旋转速度考虑搅拌器1是15转,20转与25每分钟转的分别。如图6和7,当绘制成函数图后,并发现旋转速度并没有太大的影响均匀性指数醋氨酚60%的填补水平。研究还发现,混合在20转与25每分钟转略好于其它转速,但在15转时性能的差异对不同速度下的搅拌机的太小是有意义的。相对同一个衰退的曲线,显示出相似的混合率。在这项研究中报道表明，在充填水平只有60%的情况下，所有的转速足以实现均匀。上述还进行了填满为85%以上水平的研究。对于这样一个高填满水平,在低速度搅拌机的中心发生许多情况，而且要求较高,单位体积的剪切应力均要达到。MgSt的流动特性被认为是由于大多数材料不同而产生的,但混合作为一个整体却对流动特性有深远的影响。此外,MgSt是一个对剪切敏感的材料。因此,期望和混合润滑相似的行为会被认为可能是毫无根据的。随后,实验2对搅拌器进行了三个旋转速度的研究:15转速,20转速与30转速,才有了相应的每分钟转速7.5、10与15。考虑两侧面充满水平都自上而下加载, 同样的60%水平,因此观察得到不同的旋转速度在混合率上并没有很大的差别。如图6和7混合曲线,搅拌器2不同旋转只是稍微变小速度。自上而下加载模式似乎对搅拌的转速有所提高(旋转速度稍低,显示改善水平的渐近性无明显改变,但发现和速度的两侧面加载模式有所增加)。比较两种搅拌机在不同旋转速度及两侧面加载和自上而下的加载模式的混合性能。比较得出充填水平60%是一直被作为搅拌机实现在一定长的时间有效的混合的条件。由于几何相似的两个搅拌机，帮助比较评价(旋转的对中央对称轴)在混合性能上的效果。图6,混合曲线说明了搅拌器2低于1那台果汁机,并注明大转动速率可以更快的混合。注意最后两相对达到直观性搅拌机也有所不同,搅拌器2显示混合态(大概由于效果缓慢的是在混合模式的水平方向)比搅拌器1直观性显示低。为了能得到类似的结果进行两侧面加载模式,如图7所示。相对搅拌器1的曲线搅拌器中2显示出旋转率比较低。因此,确认旋转搅拌器方向是否垂直对于转轴混合均匀有所帮助与提高，然而,为材料检查了这里,转动频率没有太多影响混合性能。最后,进行了比较两种加载模式之间搅拌机情况。再次,以达到合理,所有的实验都进行比较15转速与60%得填补水平。如图8,表明搅拌机自上而下加载得更迅速,而其相对标准偏差衰退,相比而言两侧面是更快的加载模式。然而,对于加载方式，搅拌器2能达到更快的处理。在过去的研究报道,所有的相对标准偏差分析曲线显示了一种普遍的趋势相对于时间,其特点是快速的最初因对流混合均匀,有一段时期是速度较慢的分散控制化或剪切典型。这一趋势显示在图9中，第一个直观性限制快速指数衰减,另一个是缓慢的衰减。第一部分代表了一种快速减少的混合流驱动(对流)，斜率的弧线,在相对坐标中是对流混合率。第二部分是驱使质点运动(色散)或由于活性医药物成分凝聚剪切而缓慢的侵蚀。当只有一个混合机制的状况,则需要严格控制能够实现的初始加载型,一个简单的传递模型表现了出来。(1)可以被使用,在过去的研究中14,在粉末系统中捕捉相对的演化。在该模型中,一个指数曲线腐朽的向高处的混合曲线,其中是标准差、是标准偏差,A是一个常数,标志着搅拌速率和N是有关系的。该模型预测实验方差会随着时间指数的推移,越靠近随机混合状态。为了描述混合率、必须计算出每个混合实验的数据。 (1)对参数值,通过最小化计算之间的误差平方和的数据和指数函数。最后的价值标准偏差()作为方差最小的值混合中取得的研究。值计算的实验对象提供不同混合比例填满,并用在加载模式和结果上。并以10号机和11号机。,如图10显示混合速率常数随百分比增加充满水平。一个更广泛的比较是与其他搅拌机如果汁机1、无隔板果汁机2以及市场上可买到的矩形搅拌器。每分钟转速20这个数字的影响因加载模式而对这四本搅拌机作了说明。搅拌器2双轴旋转搅拌速率常数是在所有搅拌器中最高的。所有搅拌机应用于该研究中,发现自上而下加载模式具有更高的表现比两侧面混合载入对混合性能更具有影响力。4. 结语填补水平影响混合时间、加载模式和轴的旋转对混合矩阵的自然流畅的性能和微晶纤维素快速和乳糖结合的性能。混合性能所产生负面影响,却被发现用在增加填补的水平。与自上而下加载比较，两侧面加载模式混合性能更好。这也确认了旋转搅拌器方向垂直于转轴帮助提高混合均匀的水平。数学混合模型是用来比较在不同搅拌器类型和加载模式下填充混合利率的水平。研究结果表明, 在双重轴搅拌机旋转中，自上而下填装模式增强，混合率水平却比较低。图1 近红外光谱技术验证曲线。用于预测方程对乙酰氨基酚浓度的样品进行测试验证了所与已知的大量的醋氨酚浓度。y轴表示浓度方程,计算出的x轴代表实际的浓度。因此一条笔直的线条在45将是最好的校正模型。图上的每个点为一个样品。在这里对乙酰氨基酚浓度的检查范围是0到8%。图2的图象表示(a)本搅拌器1和(b)本搅拌器2显示相应的轴旋转图3 装运原理在研究中使用模式。在自上而下加载，微晶纤维素加载第一放入搅拌器中f跟随在顶部，在两侧面加载微晶纤维素被放置在底部,然后对乙酰氨基酚是只有已筛只有在上半部分的搅拌器中,使微晶纤维素能够进行夹在乳糖中间。图4 (a)采样器(b)顶视图的取样位置方案图6 混合曲线进行自上而下载实验中,有60%的填补水平。图示相对则是功能转数。实验虚线放入搅拌机1,而坚实的数据线代表搅拌器2。图8 混合曲线比较的搅拌机搅拌2,自上而下和两侧面加载模式。实验虚线放入搅拌机1,而坚实的线代表数据点代表搅拌器2。实验在进行每分钟15转,有60%的填充水平。图9 一个典型的混合,因为转数相对，所以这两个实线强调了两个不同的混合体系。图10 混合性能水平评估三种不同的填补搅拌机2。进行试验60%,70%和80%填补水平,在每分钟15转自上而下载入。搅拌速率常数(值)的构想在功能上发现减少填补水平和增加充满水平。图11 混合性能与本搅拌机随着加载模式进行了比较,有60%的填充水平。搅拌速率常数值的在不同加载模式下，而且本搅拌机与无隔板的都如上所示,搅拌器2比搅拌器1有一个更好的混合性能比。无论搅拌器中使用哪种加载模式，自上而下加载与两侧面加载相比也有显著的效果。Comparing mixing performance of uniaxial and biaxial bin blendersAmit Mehrotra, Fernando J. MuzzioDepartment of Chemical and Biochemical Engineering, Rutgers University, Piscataway, NJ, 08855, United Statesa b s t r a c ta r t i c l ei n f oArticle history:Received 17 February 2009Received in revised form 30 May 2009Accepted 14 June 2009Available online 27 June 2009Keywords:Powder mixingCohesionBlenderMixerRelative standard deviationNIRAcetaminophenThe dynamics involved in powder mixing remains a topic of interest for many researchers; however thetheory still remains underdeveloped. Most of the mixers are still designed and scaled up on empirical basis.In many industries, including pharmaceutical, the majority of blending is performed using “tumblingmixers”. Tumbling mixers are hollow containers which are partially loaded with materials and rotated forsome number of revolutions. Some common examples include horizontal drum mixers, v-blenders, doublecone blenders and bin blenders. In all these mixers while homogenization in the direction of rotation is fast,mediated by a convective mixing process, mixing in the horizontal (axial) direction, driven by a dispersiveprocess, is often much slower. In this paper, we experimentally investigate a new tumbling mixer that rotateswith respect to two axes: a horizontal axis (tumbling motion), and a central symmetry axis (spinningmotion). A detailed study is conducted on mixing performance of powders and the effect of criticalfundamental parameters including blender geometry, speed, fill level, presence of baffles, loading pattern,and axis of rotation. In this work Acetaminophen is used as the active pharmaceutical ingredient and theformulation contains commonly used excipients such as Avicel and Lactose. The mixing efficiency ischaracterized by extracting samples after pre-determined number of revolutions, and analyzing them usingNear Infrared Spectroscopy to determine compositional distribution. Results show the importance of processvariables including the axis of rotation on homogeneity of powder blends. 2009 Elsevier B.V. All rights reserved.1. IntroductionParticle blending is a required step in a variety of applicationsspanning the ceramic, food, glass, metallurgical, polymers, andpharmaceuticals industries. Despite the long history of dry solidsmixing (or perhaps because of it), comparatively little is known of themechanisms involved 13. A common type of batch industrial mixeris the tumbling blender, where grains flow bya combination of gravityand vessel rotation. Although the tumbling blender is a very commondevice, mixing and segregation mechanisms in these devices are notfully understood and the design of blending equipment is largelybased on empirical methods. Tumblers are the most common batchmixers in industry, and also find use in myriad of application as dryers,kilns, coaters, mills and granulators 48. While free-flowingmaterials in rotating drums have been extensively studied 9,10,cohesive granular flows in these systems are still not completelyunderstood. Little is known about the effect of fundamental param-eters such as blender geometry, speed, fill level, presence of baffles,loading pattern and axis of rotation on mixing performance ofcohesive powders or the scaling requirements of the devices.However, conventional tumblers, rotating around a horizontal axis,all share an important characteristic: while homogenization in thedirection of rotation is fast, mediated by a convective mixing process,mixing in the horizontal (axial) direction, driven by a dispersiveprocess, is often much slower.In this paper, we experimentally investigate a new tumbling mixerthat rotates with respect to two axes: a horizontal axis (tumblingmotion), and a central symmetryaxis (spinning motion). We examinethe effects of fill level, mixing time, loading pattern and axis ofrotation on the mixing performance of a free-flowing matrix of FastFlo lactose and Avicel 102, containing a moderately cohesive API,micronized Acetaminophen. We use extensive sampling to character-ize mixing by tracking the evolution of Acetaminophen homogeneityusing a Near Infrared spectroscopy detection method. After materialsand methods are described in Section 2, results are presented inSection 3, followed by conclusions and recommendations, which arepresented in Section 4.2. Materials and methodsThe materials used in the study are listed in Table 1, along withtheir size and morphology. Acetaminophen is blended with com-monly used excipients and is used as a tracer to evaluate the degree ofhomogeneity achieved as a function of number of revolutions.Acetaminophen is one of the drugs most widely used in mixingstudies, and Avicel and Lactose are commonly used pharmaceuticalPowder Technology 196 (2009) 17 Corresponding author. Tel.: +1 732 445 3357; fax: +1 732 445 2581.E-mail address: muzzio (F.J. Muzzio).0032-5910/$ see front matter 2009 Elsevier B.V. All rights reserved.doi:10.1016/j.powtec.2009.06.008Contents lists available at ScienceDirectPowder Technologyjournal homepage: /locate/powtecexcipients. In the interest of brevity their SEM images are not includedin this paper, but can be found in “Handbook of Pharmaceuticalexcipients”.2.1. Near infrared spectroscopyAcetaminophen homogeneity was quantified using near infraredspectroscopy. A calibration curve was constructed for a powdermixture containing (in average) 35% avicel PH 102, 62% lactose and 3%acetaminophen. Near infrared (NIR) spectroscopy can be a useful toolto characterize acetaminophen. Samples are prepared by keeping theratio of Avicel to lactose randomized in order to minimize effects ofimperfect blending of excipients during the actual experiments onthe accuracy of the results. The Rapid Content Analyzer instrumentmanufactured by FOSS NIR Systems (Silver Spring, MD) and Visionsoftware (version 2.1) is used for the analysis. The samples areprepared by weighing 1 g of mixture into separate optical scintillationvials; (Kimble Glass Inc. Vineland, NJ) using a balance with anaccuracy of 0.01 mg. Near-IR spectra are collected by scanning in therange 11162482 nm in the reflectance mode. Partial least square(PLS) regression is used in calibration model development using thesecond derivative mathematical pretreatment to minimize theparticle size effects. As shown in Fig. 1, excellent agreement isachieved between the calibrated and predicted values.2.2. Binblendersusedinthisstudy:uni-axialblender(Blender1),bi-axialblender (Blender 2)Due to its widespread use, a cylindrical blender 1 with a capacityof 30 L is chosen as a reference blender in the study. As shown inFig. 2, this blender has a circular cross section and tapers at thebottom. It can be used with or without baffles, which are mounted ona removable lid. In this study all the experiments are conductedwithout the use of baffles. Mixing performance in this device is usedto provide a base-line for evaluating the mixing performance of anewly developed blender 2 with a capacity of 40 L, which is alsocylindrical, in order to determine the effect of dual axis of rotation onmixing performance. The blender shown in Fig. 2(b) has two axis ofrotation. The spinning rate of precession relative tothe central axis ofsymmetry is geared tobe halfof thatof therateofrotationaroundthehorizontal axis.2.3. Experimental methodTwo types of initial powder loading used in the experiments: topbottom loading and sideloading, which are schematically repre-sented in Fig. 3. To avoid agglomeration, the API, acetaminophen, wasdelumped prior to loading it into the blender by passing it through a35mesh screen. In order tocharacterize mixingperformance, a groovesampler was used to extract samples from the blenders at 7.5, 15, 30,60, 120 revolutions. The thief was carefully inserted in the bin, and acore was extracted at each point of insertion (each “stab”) minimizingperturbation to the powder bed remaining in the blender. Approxi-mately 7 samples are taken from each thief stab, and a total of fivestabs are used at each sampling time, as shown in Fig. 4 so a total of35 samples are taken at each sampling point.The experimental plan used in this study is as follows: Fill level: blender 160% Fill level: blender 260%, 70%, 80% Loading pattern: blender 1 sideside loading, topbottom loading Loading pattern: blender 2 sideside loading, topbottom loading Speed: blender 115 rpm, 20 rpm, 25 rpm Speed: blender 2 rotational/spinning:15/7.5 rpm, 20/10 rpm,30/15 rpm Sampling time: blender 1, blender 27.5, 15, 30, 60, 120 revolutions3. ResultsThe homogeneity index used is the RSD, where C is theconcentration of each individual sample, C_is the average concentra-tion of all samples and n is the total number of samples obtained at agiven sampling time.RSD =SC; where S =ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffinPC2PC2n n 1sWe examine the effect of fill level on mixing performance.Previously there have been studies on the effect of fill level in theBohle bin blender, Gallay bin blender and V-blender and double coneblender 1113. All the aforementioned blenders have only one axisof rotation, therefore the objective of this study is to examine howdual axis impact mixing performances at high fill levels. To avoidrepetition, studies for fill level are not conducted for bin blender 1.Results available from a previous study using MgSt as a tracer showedthat mixing in a uni-axial blender slowed down quite dramatically asthe fill level exceeded 70%. Moreover, results for acetaminophen canbe assumed to be similar to those obtained in previous work byMuzzio et al. 11,13, for a single axis rectangular bin blender 11,which have shown that even after few hundred revolutions homo-geneity achieved with a 80% fill level is very poor as compared to 60%fill level.To examine the effect of fill level in a dual axis blender, experi-ments were performed in blender 2 with the top-bottom loadingpattern for a rotational speed of 15 rpm and with spinning speed of7.5rpm.Thefilllevelsexaminedare60%,70% and80%respectivelyandsamples are taken after 7.5, 15, 30, 60,120 revolutions. Typical resultsare shown in Fig. 5, which shows the RSD vs. number of blenderrevolutions. As expected for non-agglomerating materials, the curvesTable 1Materials studied in this paper.NameSize and morphologyVendor, City, StateFast-Flo Lactose100 , sphericalForemost farms, Newark, NJAvicel PH 102 Microcrystallinecellulose90 , needle-likeFMC, Rothschild, WIAcetaminophen40 , needle-likeMallinckrodt, St Louis, MOFig. 1. Near Infrared (NIR) spectroscopy validation curve. The equation used to predictacetaminophen concentration is validated by testing samples with known amounts ofacetaminophen concentration. The y axis represents the concentration calculated fromthe equation and the x axis represents the actual concentration. Thus a perfectlystraight line at 45 would represent the best calibration model. Each point on the graphrepresents a single sample. The concentration of acetaminophen examined here rangesfrom 0 to 8%.2A. Mehrotra, F.J. Muzzio / Powder Technology 196 (2009) 17Fig. 2. Pictorial representation of (a) bin blender 1 and (b) bin blender 2 showing the corresponding axis of rotation.Fig. 3. Schematicoftheloadingpatternusedinthestudy.Intopbottomloading,AvicelisloadedfirstintotheblenderfollowedbyLactoseontopofitandfinallyAcetaminophenisuniformlysieved over. In sideside loading avicel is placed at the bottom and then Acetaminophen is only sieved only in half part of the blender and is sandwiched between lactose and Avicel.Fig. 4. (a) Thief sampler (b) top view of the sampling position scheme.Fig. 5. Mixing curves for different fill levels in blender 2. The RSD of acetaminophen is plotted as a function of number of revolutions. The loading pattern in top-bottom and theblender rotational speed is 15 rpm with spinning speed of 7.5 rpm.3A. Mehrotra, F.J. Muzzio / Powder Technology 196 (2009) 17show a rapidly decaying region. The slope of the curves in this region,in semi-logarithmic coordinates, is used to define the mixing rate. Thecurves then level off to a plateau that indicates the maximum degreeof homogeneity that is achievable in the blender for a give material.Similar to previous studies with other tumbling blenders we ob-servethat blending performance is adverselyaffected byincreasing filllevels. As shown in Fig. 5, the curve for 80% fill performs more poorlythan those for 60% and 70% fill; as fill level increases, RSD curves decaymore slowly, signifying a slower mixing process. However, the effect isnot as pronounced as in other bin blenders and after about only 100revolutions, the same plateau (the same asymptotic blend homo-geneity) is achieved for all three fill levels.Next, the effect of rotational speed is investigated in the blender 1with one axis of rotation and is compared to the blender 2 with dualrotation axis. Experiments were conducted for both blenders withtop-bottom and side-side loading. Experiments were performed at60% fill level and the rotation speeds considered for blender 1 are15 rpm, 20 rpm and 25 rpm respectively. As shown in Figs. 6 and 7,whenplotted as a function of blender revolutions, there is not much ofan effect of rotation speed on the homogeneity index (RSD) ofacetaminophen at 60% fill level. It is observed that mixing perfor-manceat 20 rpmand25 rpmis slightly better than at 15 rpm,howeverthe differences in the performance of the blender under differentspeeds are probably too small to be significant. RSD curves decay withthe same slope, indicating similar mixing rates. In the study reportedhere, the fill level is only 60%, and all the rotational speeds are enoughto achieve homogenization. The aforementioned studies were con-ducted at 85% fill level. For such a high fill level, at low speeds, astagnant core is known to occur at the center of many blenders,requiring higher shear stress per unit volume to achieve homogeniza-tion. Moreover, the flow properties of MgSt are known to be stronglydifferent than those of most materials, and are known to have a deepFig. 6. Mixing curves for top-bottom loading experiments with 60% fill level. RSD is plotted as a function of number of revolutions. Dotted lines correspond to experiments in theblender 1, while solid lines represent data points from the blender 2.Fig. 7. Mixingcurvesforsidesideloadingexperimentswith60%filllevel.RSDisplottedasafunctionofnumberofrevolutions.Dottedlinescorrespondtoexperimentsintheblender1,while solid lines represent data points from the blender 2.4A. Mehrotra, F.J. Muzzio / Powder Technology 196 (2009) 17impact on the flow properties of the mixture as a whole. Furthermore,MgSt is famously known to be a shear sensitive material. Thus anexpectation that lubricated and unlubricated blends would showsimilar behavior with respect to shear is probably unwarranted.Subsequently, experiments were performed using the blender 2 atthree rotation speeds: 15 rpm, 20 rpm and 30 rpm, and as explainedbefore, the corresponding spinning speeds were 7.5 rpm, 10 rpm and15rpm.Filllevelconsideredfor both side-side andtop-bottomloadingwas 60%.Again, it was observed that varying rotation and spinning speedsdidnot makemuchdifferenceinmixingrate.As showninFigs.6and7,mixing curves for blender 2 vary only slightly with rotation speed. Forthe top-bottom loading pattern it appears that mixing improvesslightly when rotation speed is increased (the plateau is slightly lowerfor higher rotation speeds, indicating an improvement in the levels ofasymptotic homogeneity), but no significant changes with speed areobserved in side-side loading pattern.The blending performance of both blenders is compared atdifferent rotation speeds for both side-side and top-bottom loadingpatterns. To make a fair comparison, the fill level was kept as 60% forboth blenders, a condition for which both blenders achieve effectivemixing at long enough times. Due to geometric similarity of the twoblenders, this comparison help evaluate the effect of spin (rotationwith respect to the central symmetryaxis) on mixing performance. Asshown in Fig. 6, the mixing curves for the blender 2 lie below those forthe blender 1 for each rotation rate, indicating faster mixing. Note thatthe final RSD asymptote reached for both blenders is also different,with the blender 2 showing a lower asymptote (better final mixedstate, presumably due to a lesser effect of the slow mixing mode in thehorizontal direction) than blender 1.Similar results were obtained for the side-side loading pattern, asdisplayed in Fig. 7. The RSD curves for the blender 1 for all the threerotation rates lie above the blender 2. It is therefore confirmed thatspinning a blender in direction perpendicular to the rotation axishelps in enhancing mixture homogeneity; however, for the materialsexamined here, the rotation rate does not have much effect on mixingperformance.Finally, a comparison is madebetweenthe two loading patterns forboth blenders. Again, to achieve a fair comparison, all experiments areperformed at 15 rpm and 60% fill level. As evident in Fig. 8, in bothFig. 8. Comparisonbetweenthemixingcurvesof theblender2andtheblender1fortopbottomandsidesideloadingpattern.Dottedlinescorrespondtoexperimentsintheblender1,while solid lines represent data points from the blender 2. Experiments are performed at 15 rpm with 60% fill level.Fig. 9. A typical mixing plot, with RSD plotted against number of revolutions. The two solid lines emphasize on the two distinctive mixing regimes.5A. Mehrotra, F.J. Muzzio / Powder Technology 196 (2009) 17blenders topbottom loading gives a more rapid decay of the RSD,indicating faster homogenization as compared to sideside loadingpattern. However, for both loading modes, blender 2 achieves fasterhomogenization.As reported in previous studies, all the RSD curves in this paperexhibit a common trend with respect to time, characterized by aninitial period of rapid homogenization due to convective mixing, fol-lowed by a period of much slower homogenization typically con-trolled by dispersion or shear. This trend is shown schematically inFig. 9. The first regime is a fastexponential decayand thesecond oneisa slow exponential asymptote to a limiting plateau. The first partrepresents a rapid reduction in heterogeneity driven by the bulk flow(convection); the slope of the RSD curve, in semi-logarithmic coor-dinates, is the convective mixing rate. The second part is driven byindividual particle motion (dispersion) or by the slow erosion of APIagglomerates due to shear.When only one mixing mechanism is present (a situation that canbe achieved by careful control of the initial loading pattern), a simplemass-transfer model, represented in Eq. (1) can be used, as in paststudies 14, to capture the evolution of the RSD in powder systems. Inthis model, an exponential curve decaying towards a plateau is fittedto the mixing curves, where is the standard deviation, the finalstandard deviation, A is an integration constant, signifies the mixingrate constant, and N is the number of revolutions. This model predictsthat the experimental variance will decay exponentially with time asit approaches the random mixture state. In order to characterizenumerically the “mixing rate,” has to be computed for each blendingexperiment. = AeN1The values for parameters A and are calculated by minimizingthe sum of squares of errors between the data and an exponentialfunction. The value of final standard deviation () is taken as thelowest value of the varianceachieved in themixing studies.The valuesfor are computed for blending experiments with different per-centage fill, and loading pattern and the results are plotted in Figs.10and 11. As shown in Fig. 10, the mixing rate constant decreases withFig.10. Mixing performance was evaluated at three different fill levels for blender 2. Experiments were performed at 60%, 70% and 80% fill levels at 15 rpm with topbottom loading.Mixing rate constant () values is plotted as a function of fill level and found to increase with decrease in fill level.Fig. 11. Mixing performance of bin blenders along with loading pattern are compared at 20 rpm with 60% fill level. Mixing rate constant () values plotted for different loadingpatterns in bin blenders with and without baffle and as shown above, blender 2 givers a better mixing performance as compared to blender 1. There is also a pronounced effect ofloading pattern, and regardless of the blender used, topbottom loading always gives a better performance compared to sideside.6A. Mehrotra, F.J. Muzzio / Powder Technology 196 (2009) 17increase in percentage fill level. A broader comparison with two otherbin blenders is provided in Fig. 11, which displays the mixing rate forthe blender 2, for the blender 1 with and without baffles, and for acommercially available rectangular blender. The figure also illustratesthe effect of loading pattern on these four bin blenders, all of themrotated at 20 rpm. It is evident that blender 2 with dual axis of rotationhas the highest mixing rate constant of the entire group. For allblenders used in this study, there is also an effect of loading pattern onmixing; it was found that topbottom loading pattern gives bettermixing performance than side-side loading.4. ConclusionThe effects of fill l

温馨提示:
1: 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。

人人文库网所有资源均是用户自行上传分享，仅供网友学习交流，未经上传用户书面授权，请勿作他用。