大模数蜗杆铣刀专用机床设计(论文+DWG图纸)带CAD图
收藏
资源目录
压缩包内文档预览：(预览前20页/共87页)
编号：22018764
类型：共享资源
大小：1.78MB
格式：ZIP
上传时间：2019-09-16
上传人：QQ24****1780
认证信息
个人认证
王**（实名认证）
浙江
IP属地：浙江
50
积分
- 关 键 词：
-
大模数
蜗杆
铣刀
专用
机床
设计
论文
dwg
图纸
cad
- 资源描述：
-
大模数蜗杆铣刀专用机床设计(论文+DWG图纸)带CAD图,大模数,蜗杆,铣刀,专用,机床,设计,论文,dwg,图纸,cad
- 内容简介：
-
附录1 中文译文常规压力对采用非牛顿学流体润滑的光滑碟片表面的作用陈好升，李疆，陈大荣，王佳道1.国家摩擦学研究所，清华大学，中国北京，1000842.北京科技大学，机械工程系，中国，100083摘要：为了研究与分析非牛顿学流体在润滑光碟表面时常规压力所产生的影响，包含这个常规作用力的一个修正的瑞诺德公式被建立。公式中对于第一常规压力不同的表述源自于瑞林-埃里克森第二流体定律和流体冲力公式。光碟表面润滑的结果被计算从而用在了的瑞诺德分析公式之中。在持久稳定的薄层润滑作用之下，常规的压力和负载受到正常速度的限制，因此在计算中可以直接省略。当光滑流体的高度变化或者润滑膜的厚度下降时，常规的速度下降，故此此时需要在计算中考虑到第一常规压力的不同所产生的影响。关键词：非牛顿学流体、第一常规压力差分、磁性数据存储系统。1.介绍正如德布鲁尼和波致所说的那样，一个非牛顿润滑是在磁性记录系统中用来避免干燥接触。事实已经证明了通过引入非牛顿学流体以高的剪切速度进行切向润滑是可以达到在光滑的覆盖表面之下显著降低压力的形成的效果。为了能够明确说明非牛顿学流体在主要碟片表面的润滑作用，李旺龙提供了一个平均瑞诺德公式并且指出幂律流体的流动影响效率在负荷能力方面比表面粗糙度更加明显。非牛顿流体的性能在对磁性光碟表面进行润滑时是重要的影响因素。常规压力作用是非牛顿学流体的特性。许多研究结果都证明了在许多润滑中常规压力的作用都有明显的增加，第一常规压力差分比第二常规压力差分更加明显。常规压力的作用在润滑中需要被分析，第一常规压力差分的计算方法也需要去研究。在这篇论文中，第一常规压力差分是一种具有可伸缩性的非牛顿流体，就像麦克斯韦尔流体，都源自于被建立的包含常规压力的润滑公式。数字思想被用在计算光碟表面的润滑作用之中。2.第一常规压力的解释第一常规压力来源于瑞林-埃里克森流体公式（1）。式中，是压力，是剪切压力的张量，是剪切速率的张量，是流体粘质系数，是黏弹性流体的第二定律系数，是由材料的时间衍生出来的。公式（1）适用于随机等同系统。在这篇论文中，卡特森等同系统被抛出在外，不以考虑。在等同系统中的非牛顿流体的微观单位在图1中已经给出，（x,y,z）是修正等同系统中用来计算用的，（z,y,x）是参考等同系统而（1，2，3）是下面等同系统中适用于微观单位的。被定义为经下等同系统的微观单位的角速度。这样的话，角速度的微观单位就是。Figure 1. Maxwell micro unit in the coordinate systems下面的等同系统（1，2，3）是一个刚性的卡特森等同系统。等同的起源被定义在了微观单位上，随着单位的移动和转动而进行等同的移动和转动。下列等同的方向经常和剪切速度的张量的方向是一致的。采用普哥理论，材料时间的起源应该可以被瑞林-埃里克森剪切速度和朱漫协方差衍生公式推导出来，在下列等同系统中，新的张量被表示为从而出现在公式（2）中，并且它还可以有在任意的等同系统中。是该方向上的速度。当润滑是理想的粘性流体的时候，下列等同系统中的主要轴的方向与相对等同系统中的主要压力轴的方向是一致的。这就意味着并且第一常规压力方差也是零。材料时间的衍生在图（2）中被定义为下列等同系统。如果材料时间的衍生是相对等同的话，下列等同系统中的微观单位的角度就应该被添加进来。从公式（4）中我们可以得出，常规压力可以用公式（5）来表示。在公式（5）中，是液体的粘性。公式右边的第二项表示出了粘性对于常规压力的作用。第三项表示出了第一常规压力方差的作用。在公式（6）中得到了表达。是缓和时间，是粘性方差。第四项表示出了第二常规压力方差的作用。通常人们认为第二常规压力方差的作用远远小于第一常规压力方差，第四项是一个省略项，第一常规压力方差在公式（7）中表示出来了。在润滑中，润滑膜的厚度远远小于其它的尺寸。比较占有支配地位的粘性和粘性变化率而言，在公式（7）中都被忽略了，第一常规压力方差被简化成了公式（8）。在公式（8）中，是缓解时间，是下列相对等同的粘性角度，是由非牛顿学流体的弹性所引起的，被认为是微观单位的黏弹性的自然频率。因此，第一常规压力方差被表示为公式（9）.总的来说，第一常规压力方差的定义如下式所示：是第一常规压力方差的功能，通过公式（9）和（10），它可以表示为公式（11）。3. 瑞诺德公式中包含第一常规压力方差为了分析第一常规压力在润滑中的作用，一个修正模式包含了第一常规压力方差的瑞诺德公式首先在稳定的薄片状润滑的条件下被建立起来。在主要光碟表面的润滑，随机相似系统中的剪切力和常规压力在等同转化之后的表达式正如公式（12）所示。公式（12）来源于等同的改变，另一个公式表达出了来自于动量公式之中的压力之间的关系，如公式（13）所示：在实际的润滑条件下，公式（13）被简化为一些最基本的假设，动量公式变成了公式（14）所示的形式。（1）惯性力和外力不被考虑时，（2）流体不能够被压缩，（3）和主要流体比较而言被忽略了。从公式（）和公式（）可知，一个修正的瑞诺德公式出现了并且被表示成为公式（15）的样式。在公式（15）中，是压力，是表面速度，是润滑膜的厚度，是常规润滑膜的运动速度。是相对量。简单的几何学示意图如图2所示。4.润滑的数学结果在这一部分中，数学思想被用于润滑结果的计算之中。基于结果而言，对受压力物体的第一常规压力方差及其负载能力都得到分析。用到的分析公式在公式（16）中都已经给出了。在公式（16）中，无量纲的参数都说明如下。为了简化计算，在稳定的薄片润滑中，其他因素诸如温度等都被认为是一个常量。超放松理论在这里被应用。4.1在稳定的薄片润滑中的数学结果非牛顿流体的第一常规压力方差将作用在压力轮廓及其负载能力。在b/2的中间部分的压力分布已表示在图3中。是润滑中的无量纲压力，并不受第一常规压力方差的影响。而是在第一常规压力方差作用之下的无量纲压力。图4反映出了负载能力。在图4中，是在第一常规压力方差作用之下的无量纲负载能力，是不受第一常规压力方差的影响的无量纲负载能力。是牛顿学流体的无量纲负载能力。从图3和图4显示的结果我们可经得出，在常规压力的作用之下润滑时压力和负载能力都有所增加。但是增加量并不是很明显。所以在润滑计算的过程中可以忽略常规压力的影响和作用。在实际润滑之中，第一常规压力方差的作用是增加负载能力，因此，忽略第一常规压力方差是一个安全的设计思想。图3. 受压力作用的物体中第一常规压力差分的作用图4. 第一常规压力对负载能力的作用从图4中，我们可以发现负载能力的变化是由粘性的变化所导致的。例如，在麦克斯韦尔流体润滑中，不同的粘性主要是由剪切速度所造成的。粘性的变化是影响润滑作用的主要因素，第一常规压力方差的作用是在小范围内增加负载能力。第一常规压力方差的作用受到了两个因素的影响。一个是材料的力学性能。从公式（11）中我们可以看出，第一常规压力方差的决定性因素是自然频率和非牛顿学流体的缓解时间。同时，速度的微分受到了剪切速度的影响。另一个因素是常规速度。在公式（16）中，约第一常规压力方差的功能受到了常规速度的约束。通常在理论分析中，常规速度考虑的很少，与理论速度相比，通常也可以被忽略。常规速度减弱了第一常规压力方差的作用。例如，在计算中被使用的变量，无量纲第一常规压力方差的数值是-36，但是计算得出的实际速度却连0.0021都不到，所以在公式（16）中右边的第二项的作用远远小于几何图形的作用。在常规速度足够大的情况下，第一常规压力方差的作用在数学计算中就需要被考虑了。受压力物体在不同的无量纲常规速度在图5中被表示出来了。随着常规速度的增加，第一常规压力作用方差的作用在受压力物体上变得越来越重要。当无量纲常规压力是表面速度的1%的时候，也就是说v=0.01，压力增量的峰值大约为5%。图5. 受压力物体在常规压力方差下的作用常规压力在真正的磁性光碟表面的润滑的时候需要被考虑。例如，在与光碟有关的实验中，光碟的飞行高度是变化的。同样，事实也证明了在受驱动的实验之中，润滑膜的厚度也下降了。包含常规速度的作用的瑞诺德公式需要被修正。4.2常规速度的作用常规速度不仅影响第一常规压力方差的作用，但是同样造成挤压作用。由各项可以推出，瑞诺德公式可以被表示为公式（17）的形式。在公式（17）中，常规速度的润滑可以被表示为公式（18）。由公式（18）和公式（17），用于数学计算的公式可以表示为公式（19）。公式（19）右边的第一项表示出了几何学的作用，第二项表示出了扩展作用，第三项代表了第一常规压力差分的作用。当v=0.01U，考虑到不同影响的受压力物体在图6中已经表示出来了。在图6中，代表受压力物体在几何润滑和第一常规压力方差的作用下的作用。并且随着正常润滑速度的增加，第一常规压力方差的影响增大，在图6中展示出的结果中，第一常规压力方差是不应该被忽略的。从结果来看，我们同样可以找出伸长作用也比第一常规压力方差的作用更加重要。如图6所示，张量作用所引起的压力的峰值比第一常规压力差分所引起的压力峰值效果要明显的多。因此，在光碟表面的润滑中，润滑张量的作用和第一常规压力差分都应该被考虑。5.结论当一个非牛顿学流体润滑被用在磁性光碟表面润滑的时候，它们的常规压力作用可以通过包含第一常规压力差分功能的修正的瑞诺德公式来计算。对于第一常规压力差分的解释源自于瑞林-埃里克森公式和动量公式，相似转换也是同样。常规压力在润滑光碟表面的时候不仅受到非牛顿学流体材料的变量的影响，同样也受到常规速度的影响。在稳定的薄片流层下，压力和负载能力在第一常规压力差分的作用下都有所增加，但是增加的作用不是很明显，因为较小的常规速度。考虑到不仅来自于理论分析，而且来自于真实的润滑计算，第一常规压力差分的润滑作用在不同的主要因素的影响下是可以被人们忽略的。当光滑面运动而常规润滑速度增加了之后，包含常规速度的作用的瑞诺德公式再次被修正。数学结果显示出了第一常规压力差分的增大作用经及在润滑计算的过程中需要被考虑。附录2 英文原文Normal Stress Effects in Slider-Disk Interface Lubrication with Non-Newtonian Fluid Chen Haosheng1*, Li Jiang2, Chen Darong1, Wang Jiadao11. State Key Laboratory of Tribology, Tsinghua University, Beijing China 100084. 2. Department of mechanology, University of Science and Technology Beijing, China, 100083 Abstract To analyze normal stress effects of non-Newtonian fluid in lubrication of the magnetic head-disk interface, a modified Reynolds equation including the effects of normal stress is established. The expression of the first normal stress difference in the equation is derived from the Rivlin-Ericksen second order flow equation and the fluid momentum equation. Lubrication results of the magnetic head-disk interface is calculated using the modified Reynolds equation. Under the condition of steady laminar lubrication, the pressure and the load capacity of non-Newtonian fluid is increased by the effect of the first normal stress difference, but the effect is constrained by the normal velocity and can be omitted in the calculation. When the slider flying height changes or the lubricant film thickness decreases, the normal velocity increases and the effect of the first normal stress difference need to be considered. Keywords: non-Newtonian fluid, first normal stress difference, magnetic data storage systems 1. Introduction As mentioned by De Bruyne and Bogy1, a non-Newtonian lubricant is used for some magnetic recording system to avoid dry contact. It has been proved that a significant reduction of pressure buildup under the slider cover can be achieved by introducing non-Newtonian shear thinning lubricant at high shear rate. To specify the behavior of non-Newtonian fluid in the lubrication of the head-disk interface, Wang-Long Li2 provides an average Reynolds equation and point out that the effect of the flow behavior index of the power-law fluid on load capacity is more significant than that of the surface roughness. The properties of non-Newtonian fluid are important factors in the lubrication of the magnetic head-disk interface. Normal stress effect is a characteristic of non-Newtonian fluid. Some research results 3-5 have proved that the effects of the normal stress in some lubricants are obviously increased, and the first normal stress difference is far more than the second normal stress difference. The normal stress effect needs to be analyzed in the lubrication, and the method to calculate the first normal stress difference needs to be investigated. In this paper, the expression of the first normal stress difference of a kind of viscoelastic non-Newtonian fluid such as Maxwell fluid is derived and the lubrication equation which contains the effect of the normal stress is established. Numerical method is used to calculate the lubriation results of magnetic head-disk interface. 2. Expression of the First Normal Stress The normal stress is derived from Rivilin-Ericksen 6 flow Eq. (1). In Eq. (1), p is the pressure, ij is the tensor of the shear stress, ij& is the tensor of the shear rate, 1 is the fluid viscosity, 2，3 are the second order coefficience of the viscoelastic fluid, tij/DD& is the material time derivative. Equation (1) is applicable for random coordinate system. In this paper, the Cartisian coordinate system is adopted. The micro unit of non-Newtonian fluid in the coordinate systems is shown in Fig. 1. The (x, y, z) is the fixed coordinate system for the calculation, the (zyx,) is the reference coordinate system and the (1, 2, 3) is the following coordinate system fixed on the micro unit. ij is defined as the angular velocity of the micro unit to the following coordinate system, ij is defined as the angular velocity of the following coordinate system to the reference coordinate system. Then, the angular velocity of the micro unit is ijijij+=. Figure 1. Maxwell micro unit in the coordinate systems The following coordinate system (1, 2, 3) is a rigid Cartisian coordinate system. The origin of coordinate is fixed on the micro unit, and the coordinate moves and rotates as the unit moves and rotates. The direction of the following coordinate is always same to that of the tensor of the shear rate. With Pragers theory, the material time derivative should be expressed by the Rivlin-Ericksen shearing rate and the Jaumann covariant derivative. In the following coordinate system, the new tensor dtdij/& is expressed by the partial derivative shown as Eq. (2) and can be used to random coordinate system. is the velocity on the direction . When the lubricant is an ideal viscosity fluid, the direction of the principal axis of the following coordinate system is same to the axis of the principal stress tensor in the reference coordinate system, that means 0= and the first normal stress difference is zero. Material time derivative in Eq. (2) is defined in the following coordinate system. If the material time derivative is in the reference coordinate, the angular of the micro unit to the following coordinate system should be added. From the Eq. (4), the normal stress can be expressed as Eq. (5)： In Eq. (5), 1 is the viscosity of the fluid. The second item on the right of the equation shows the effect of the viscosity to the normal stress. The third item shows the effect of the first normal stress difference. 2 is expressed as Eq. (6). is relaxtion time and is the differential viscosity7. The fourth item shows the effect of the second normal stress difference. It is commonly recognized that the second normal stress difference is far less than the first normal stress difference, the fourth item is omitted and the expression of the first normal stress difference is expressed as Eq. (7). In the lubrication, the lubricant film thickness is far less than other dimensions. Compared with the dominating velocity u and velocity gradient yu, xv and xay are omitted in Eq. (7), the first normal stress difference is simplified to Eq. (8). In Eq. (8), is the relaxation time, is the angular velocity of the following coordinate to the reference coordinate. is caused by the elasticity of non-Newtonian fluid and is considered as the natural frequency n of the viscoelastic micro unit . Thus, the first normal stress difference is specified as Eq. (9). Generally, the definition of the first normal stress difference is 1& is the function of the first normal stress difference, with Eq. (9) and (10), the )(1& is expressed as Eq. (11). 3. Reynolds Equation including the First Normal Stress Difference To analyze the effect of the normal stress in lubrication, a modified form of Reynolds equation that includes the first normal stress difference is firstly established under the condition of the steady laminar lubrication. In head-disk interface lubrication, the expression of the shear stress and the normal stress in the random coordinate system are shown as Eq. (12) after the conversion of the coordinates. Eq. (12) is derived from the conversion of the coordinates, another equation showing the relation between the pressure and the stress is derived from the momentum equation shown as Eq. (13) Under the real lubrication condition, Eq. (13) is simplified with some basic assumptions, and the momentum equation is changed to Eq. (14). (1) The inertia force and the external force are not considered, (2) The fluid can not be compressed, (3) Compared with the principal flow are omitted. With Eq. (14) and Eq. (12), a modified Reynolds equation is derived and shown as Eq. (15). In Eq.(15), p is the pressure, U is the surface velocity, h is the thickness of the lubricant film, v is the velocity normal to the lubricant film. xyz are coordinates. The simplified slider geometry is shown as figure 2. 4. Numerical Results of Lubrication In this section, numerical method is used to calculate the lubrication results. Based on the results, the effect of the first normal stress difference to the pressure profile and the load capacity is analyzed. The dimensionless equation used in calculation is shown as Eq. (16). In Eq. (16), the dimensionless parameters are illustrated as follows. To simplify the calculation, other factors such as temperature are considered as constant under the stable laminar lubrication, and the over relaxation method is used. 4.1 Numerical results in stable laminar lubrication The first normal stress difference of non-Newtonian fluid will affect the pressure profile and the load capacity. The pressure of the intermediate cross-section at b/2 is shown in Fig. 3. 0p is the dimensionless pressure of the lubricant which is not affected by the first normal stress difference, 1p is the dimensionless pressure which is under the effect of the first normal stress difference. Corresponding load capacities are shown in Fig. 4. In Fig. 4, W1 is the dimensionless load capacity under the effect of the first normal stress difference, W2 is the dimensionless load capacity not considering the effect of the first normal stress difference. Wn is the dimensionless load capacity of Newtonian fluid. Figure 3. Effect of the first normal stress difference to the pressure profile Figure 4. Effect of the first normal stress difference to the load capacity From the results shown in Fig. 3 and Fig. 4, the pressure and the load capacity of the lubricant increase under the effect of the normal stress. But the increment is not significant. So the effect of the normal stress can be omitted in lubrication calculation. In real lubrication, the effect of the first normal stress difference is to increase the load capacity, omitting the first normal stress difference is a safe design method. From Fig. 4, we may also find that the variation of the load capacity is caused principally by the variation of the viscosity. For example, in Maxwell fluid lubrication, the differential viscosity is affected by the shearing rate greatly. The variation of the viscosity is the key factor to affect the lubrication effect, and the effect of the first normal stress difference is to increase the load capacity in small variation range. The effect of the first normal stress difference is affected by two factors. One is the material dynamic property. From equation (11), the first normal stress difference is determined by the natural frequency and the relaxtion time of non-Newtonian fluid. Also, the differential viscosity is affected by the shearing rate. The other factor is the normal velocity. In Eq. (16), the function of the first normal stress difference is constrained by the normal velocity v. Commonly in theoretical analysis, the normal velocity is considered small and is omitted compared with principal velocity .The normal velocity weakens the effect of the first normal stress difference. For example, under the parameters used in calculation, the value of the dimensionless first normal stress difference is -36, but the calculated normal velocity Uv is no more than 0.0021, so the effect of the second item on the right side of the Eq. (16) is far less than the geometric effect. If the normal velocity is large enough, the effect of the first normal stress difference needs to be considered in the numerical calculation. The pressure profiles under different dimensionless normal velocities are shown in Fig. 5. With the increment of the normal velocity, the effect of the first normal stress difference to the pressure profile become more and more important. When the dimensionless normal stress is 1% of the surface velocity, that is 01.0=v, the increment of the pressure peak is about 5%. Figure 5. Effect of the normal stress difference to the pressure profile Normal velocity sometimess may be considered in the true magnetic head-disk interface lubrication. For example, in the head-disk contact dection experiment 8, the flying height of the slider changes. Also, it has been proved that the lubricant film thickness decreases under flying heads during drive operation9,10. The Reynolds equation needs to be modified to include the effect of normal velocity. 4.2 Effect of normal velocity The normal veloctiy not only affects the effect of the first normal stress difference, but also causes extrusion effect 11. With the item of the extrusion effect, the Reynolds equation is expressed as Eq. (17). In Eq. (17),. The normal velocity of the lubricant is expressed as Eq. (18). With Eq. (18) and Eq. (17), the equation used for numerical calculation is shown as Eq. (19). The first item on the right of Eq. (19) represents the effect of the geometry, the second item represents the extrusion effect, the third item represents the effect of the first normal stress difference. When , the pressure profiles are shown in Fig. 6 considering different effects. Figure 6. Pressure profiles under different effects In Fig. 6, 0p represents the pressure profile under the only effect of lubricant geometry. 1p represents the pressure profile under the effect of the geometry and the extrusion effect. 2p represents the pressure profile under the effect of the geometry and the first normal stress difference. And as the normal velocity of the lubricant increases, the effect of the first normal stress difference is enlarged, the first normal stress difference should not be omitted according to the results shown in Fig. 6. From the results, we may also find that the extrusion effect is more important than the first normal stress difference. Shown in Fig. 6, the increment of the pressure peak caused by the extrusion effect is far more than the increment caused by the first normal stress difference. So, in head-disk interface lubrication, the effect of the lubricant extrusion and the first normal stress difference should both be considered. 5. Conclusions When a non-Newtonian lubricant is used in the magnetic head-disk interface lubrication, its normal stress effect can be calculated by a modified Reynolds equation which includes a function of first normal stress difference. The expression of the first normal stress difference is derived from the Rivlin-Ericksen equation and the momentum equation, together with the coordinates conversion. The effect of the normal stress in the head-disk interface lubrication is not only affected by the non-Newtonian fluid material parameters, but also is affected by the normal velocity. Under the steady laminar flow, the pressure and the load capacity are increased by the effect of the first normal stress difference. But the effect is not significant because of the small normal velocity. Considering both from the theoretical analysis and from the true lubrication c
- 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。
川公网安备: 51019002004831号