法兰盘斜孔和径向孔加工卧、斜轴回转分度钻床夹具设计
收藏
资源目录
压缩包内文档预览：
编号：34306564
类型：共享资源
大小：3.76MB
格式：ZIP
上传时间：2019-12-24
上传人：机****料
认证信息
个人认证
高**（实名认证）
河南
IP属地：河南
50
积分
- 关 键 词：
-
法兰盘
径向
加工
斜轴
回转
分度
钻床
夹具
设计
- 资源描述：
-
法兰盘斜孔和径向孔加工卧、斜轴回转分度钻床夹具设计,法兰盘,径向,加工,斜轴,回转,分度,钻床,夹具,设计
- 内容简介：
-
科技译文Improved Workpiece Location Accuracy Through Fixture Layout OptimizationAbstractInaccuracies in workpiece location lead to errors in position and orientation of a machined feature on the workpiece. The ability to accurately locate a workpiece in a machining fixture is strongly influenced by rigid body displacements of the workpiece caused by elastic deformation of loaded fixture-workpiece contacts. This paper presents a model for improving workpiece location accuracy in fixturing. A discrete elastic contact model is used to represent each fixture-workpiece contact. Reduction in workpiece locating error due to rigid body displacements is achieved through optimal placement of locators and clamps around the workpiece. The layout optimization model is also shown to improve the overall workpiece deflection and reaction force characteristics.1.IntroductionThe accuracy of location of a machined feature depends on the machining fixtures ability to precisely locate the workpiece relative to the machine tool axes. Workpiece location in a fixture is significantly influenced by localized elastic deformation of the workpiece at the fixturing points. These deformations are caused by the clamping force(s) applied to the workpiece. For a relatively rigid workpiece the localized elastic deformations cause it to undergo rigid body translations and rotations which alter its location with respect to the cutting tool. It is therefore important to minimize such effects through optimal design of the fixture layout.Previous work in fixture layout optimization has focused on the use of finite element and rigid body models. Menassa and DeVries 1, Rearick et al. 2, Trappey et al. 3, and Cai et al 4 used finite element models of the fixture-workpiece system as input to the layout optimization. In these works the fixture layout design is formulated as a constrained nonlinear optimization problem. The goal is to determine the positions of locator-clamp pairs that will minimize a nonlinear function of the elastic deformation at selected points on the workpiece. Such a formulation requires solution of the complete finite element model during each iteration of the optimization process. Hence, the technique is computationally intensive.DeMeter 5 presented a min-max algorithm to determine the optimal fixture layout and clamping force intensity that minimizes the maximum contact force. In this study the workpiece and fixture were assumed to be perfectly rigid. Such a formulation does not allow the effect of workpiece displacement on locating errors to be minimized directly. Recently, Gui et al 6 reported a model for improving workpiece location accuracy by optimizing the clamping force. They model the elasticity of fixtureworkpiece contacts using linear springs of known stiffness. However, methods for determining the contact stiffness are not addressed. In addition, the fixture layout is assumed fixed for a given workpiece and cutting force system. This paper presents a method that directly minimizes workpiece location errors due to localized elastic deformation of the workpiece at the fixturing points by optimally placing the locators and clamps around the workpiece. The method considers the fixtureworkpiece contact to be linearly elastic and uses closed-form contact stiffness models derived from well-known contact mechanics problems. Also, the method outlined here is computationally less intensive than the finite element approach. The following sections give details of the underlying models and constraints used to formulate the fixture layout optimization procedure. Model simulations are presented to demonstrate the ability of the method to minimize workpiece location errors through optimal arrangement of locators and clamps.2.Fixture Layout Optimization Fixture layout optimization requires formulation of an objective function and constraints. In this paper our objective is to minimize the effect of localized elastic deformation of the workpiece at the fixturing points on workpiece location. As stated earlier, the elastic deformations cause the workpiece to undergo a rigid body motion, which in turn shifts the workpiece location. The objective function for optimization is constructed as follows. Objective Function Formulation. Consider a solid rectangular workpiece held in a fixture consisting of several locators and clamps (see Figure 1). The fixture is typically very rigid compared to the workpiece. It can hence be assumed that the locators do not undergo any rigid body displacement. In contrast, forces acting on the workpiece at the locating and clamping points cause the workpiece to translate and rotate in the global coordinate system. Assume that the rigid body motion of the workpiece due to normal and tangential elastic deformations at the ith fixturing point is given by vector i= xiyizi T . Note that the components of i are expressed in the local coordinate system fixed to the ith point. Geometric transformations are applied so that the rigid bodymotion due to deformation at the ith fixturing point is expressed in the global coordinatesystem as: where Tgi is a general rotation matrix that transforms quantities expressed in the ith local coordinate system into the global coordinate system. Thus, the total rigid body motion ofthe workpiece due to elastic deformations at all the fixturing points is: where N is the total number of locators and clamps.In order to minimize the effect of rigid body motion on workpiece location, a quadratic objective function for fixture layout optimization can now be formulated as follows:Note that the above expression is not an explicit function of the fixture element positions.But the rigid body motion i , and therefore , is dependent on the fixturing forces which are in turn uniquely determined by the layout of fixturing points and elastic contact properties. Hence, changing the fixture layout changes the value of the objective function indirectly.Fixture-Workpiece Contact Constraints. The fixture-workpiece system is subject toseveral contact constraints that the optimum fixture layout must also satisfy. In particular, constraints specifying the geometric compatibility of elastic deformation andfrictional resistance are needed. These constraints are developed using a discrete elasticcontact modeling approach similar to that of Conry and Seireg 7, and Sinha and Abel8.The workpiece is assumed to be elastic in the contact region and rigid elsewhere.The fixture is assumed to be completely rigid. At each fixturing point a square contact surface tangent to the fixture and workpiece surfaces is assumed. The contact surface isdiscretized into a grid containing M square elements as shown in Figure 2. A distributed normal force of intensity p ji and a distributed friction force of intensity (q) (q) xjiyj2 i 2 +are assumed to act across an arbitrary element j of the ith contact surface. The total normal ( Pi ) and friction (Qi ) forces acting at the ith fixturing point are then given by:The localized deformation at a fixturing point causes distant points in the workpiece to undergo a rigid body motion in the normal direction given by zi . If s ji isthe initial separation of the fixture and workpiece surfaces for the jth element at the ith fixturing point, the normal deformation, wji , must satisfy the following contact condition9:The equality sign applies to points that lie inside the equilibrium contact area and theinequality sign for outside points.Orthogonal components of tangential deformation, uji and v ji , produced by the frictional forces acting at a fixturing point lead to tangential rigid body motions xiy, i ,respectively. The deformation and rigid body motion should satisfy the following geometric compatibility conditions 9:where the equality and inequality signs apply for slip and no slip cases, respectively.Contact Deformation Model.The workpiece is assumed to be a linear elastic solid in the vicinity of the fixturing points. Hence, by linear superposition, the normal deformation in the jth element of the ith contact region can be written as: where e e e jknjkxjk, , y are the flexibility influence coefficients for deformation in the normal direction due to fixturing forces in the normal (n) and tangential directions (x, y).Similarly, the x and y components of tangential deformation are given by: where are the normal and tangential flexibility influence coefficients for workpiece deformation in the local x and y directions at the ith fixturing point, respectively.In this paper the influence coefficients are derived from closed-form solutions forthe contact compliance of an elastic half-space subjected to distributed normal and tangential loads. Details of the influence coefficient models may be found in 8, 9.Contact Friction Constraint. Coulomb friction is assumed to apply at each fixturing point. This implies a nonlinear relation between the normal and frictional forces acting at a fixturing point, i.e., (q) (q) p xj where s is the coefficient of static friction for the fixture-workpiece material pair. For simplicity, a linearized version of this constraint is used: Static Equilibrium Constraint. The workpiece must be in static equilibrium after application of fixturing forces at the selected points. This constraint is given by the following force and moment equilibrium equations: F = 0 (12) M = 0 (13)where the forces and moments are expressed in terms of the elemental normal ( p ji ) and tangential forces ( qxji , qyji ) acting at the contact surface for each fixturing point.Clamping Force Constraint. When the clamping force applied by the clamps isspecified, it is necessary that the sum of the elemental normal forces at the clampingpoint equal the specified force. This constraint is expressed as follows: where C is the number of clamps in the fixture. In this paper the clamping force isassumed to be known. In general however the clamping force could be treated as adesign variable in the layout optimization process 5.Fixture Element Position Constraints. The fixture layout optimization procedure seeksto find the optimal locations of the fixturing points. In general, fixture element positionson a workpiece datum surface cannot be chosen randomly and are often constrained bythe geometric complexity of the workpiece surfaces, size and location of the features tobe machined, and other process related issues. Hence, the position of a fixture element isrestricted to a bounded region on the datum surface. In this paper each fixture elementposition is constrained to lie inside a convex polygonal region. A sequence of orderedstraight edges represents each convex polygon. Mathematically, the system of linearinequalities constructed from the line equations for all ordered edges (for N fixturingpoints) is used to specify the bounded region:A X C p p p (15)WhereAndThe elements of Ai and ci are coefficients of the line equations of the polygon edges usedto specify the polygon boundary for the ith point, xi is the position vector (global) to the ithpoint on the workpiece surface, and li is the number of ordered edges making up thebounding polygon for the ith point.The above inequalities can now be used to easily establish the location of afixturing point relative to its polygon boundary. Points inside or on the boundarycompletely satisfy the above inequalities whereas points outside the bounded region do not 10.Layout Optimization Model. The complete fixture layout optimization problem cannow be formally stated as follows:Minimize ：Subject to:Bounds: pji 0i = 1, , N; j = 1, , M; k = 1, , CNote that the normal compatibility constraint has been multiplied by -1 to convert it intoa type inequality. Also, by definition, the friction force components qxji and qxji lie inthe contact surface plane, and p ji is assumed to be positive when directed into the9workpiece surface.3.Solution MethodA nonlinear programming method is used to solve the above layout optimizationproblem. Specifically, Zoutendijks method of feasible direction 11 is used. Thismethod is similar to that used by DeMeter 5 and involves the solution of the followinggeneral nonlinear program:Minimize f(x)Subject to Gx b (linear inequality constraint)H(x) = 0 (nonlinear equality constraint)Ex = e (linear equality constraint)where x is the feasible solution. For the nonlinear program given in equation (16) thesolution x =F X pT where:Note that in addition to position of the fixturing points, Xp, the solution procedure treatsthe fixturing forces F and rigid body motion also as design variables during theoptimization process. This is because the fixturing forces and rigid body motion dependon the fixture layout and are determined uniquely for each layout by the physics of theproblem.The first linear inequality constraint is constructed by combining all the inequality constraints given in equation (16). The second nonlinear constraint arises from themoment equilibrium equation in (16). Finally, the linear equality constraint equation isconstructed by combining all the equality constraints listed in (16). For the problem athand, G, H, and E result in matrices with the following sizes: (4MN+N liiN= 1) x(3MN+6N), 3 x (3MN+6N), and (3+C) x (3MN+6N). Note that x is a (3MN+6N) x1 column vector.The method of feasible directions solves the nonlinear program by moving from a initial feasible solution to an improved feasible solution. This is accomplished in four steps: a) find initial feasible solution, b) determine line search direction, c) determine step size, d) solve quadratic program. By iterating between steps (b) and (d) furtherimprovements in the feasible solution can be obtained. Mathematical details of step (b)through (d) can be found in reference 11.The initial feasible solution x is obtained by solving the elastic fixture-workpiececontact model for the initial layout. This is done by minimizing the total complementaryenergy for the fixture-workpiece system. Details of the solution procedure andexperimental validation can be found in 7, 8, 12. Note that the contact model needs tobe solved only once at the beginning to obtain the initial feasible solution. Thereafter,the layout optimization model relies on the contact constraints and the contactdeformation model to compute valid rigid body displacements and fixturing forces.4.Results and DiscussionThe fixture layout optimization model and solution algorithm has been implemented in MATLAB (version 5.0). The capability of the model is illustrated through an example. Consider the initial fixture layout shown in Figure 3. This layout uses a 4-2-1 location scheme with two simultaneously actuated hydraulic clamps to hold the workpiece against the locators. Table 1 lists the positions and orientations of thefixture elements in the initial layout. Locators L1-L4 and clamps C1-C2 have sphericaltips while locators L5-L7 have small area planar tips (area = 63 mm2). A clamping forceof 703 N is assumed to act at each clamping point. The workpiece is a 127mm x 127mmx 382 mm block of Aluminum 7075-T6. The Youngs modulus (E) and Poissons ratio() for the workpiece are 70.3 GPa and 0.354 respectively, and 201 GPa and 0.296respectively for the fixture elements.The initial feasible solution vector x is computed by solving the fixture-workpiececontact model for the initial fixture layout using the minimum complementary energymethod. The layout optimization problem is then solved using the four step iterationprocedure outlined in the previous section. The fixture element position constraints usedfor this problem are given in Table 2. The improved fixture layout that minimizes the11effects of rigid body motion is given in Table 1. The objective function value is reducedfrom 528 m2 to 426 m2.The impact of the optimization process on the fixture layout is shown in Figure 4.The initial fixture layout was intentionally designed to violate well-known empirical“locating rules” 13. For instance, it is standard practice to position the locators on adatum surface as far apart as possible. This is done to ensure the best possible locationalstability of the workpiece. In the initial layout, locators L1-L2 and L4-L7 clearly do notsatisfy this rule. Also, the initial position of clamps C1 and C2 do not provide adequateclamping stability. It is clear from Figure 4 and Table 1 that the layout optimizationmodel gives a solution that supports the empirical rules. Specifically, L1 and L2 arepushed as far apart as possible. Also, locators L4-L7 are spread out on the primarydatum plane so as to include the projected center of gravity of the workpiece inside thebounding polygon formed by joining L4-L7. This improves workpiece stability in thefixture. The new position of clamp C1 is approximately half-way between locators L1and L2. Similarly, clamp C2 and locator L3 directly oppose each other in the improved lay out.If, for simplicity, only the normal component of rigid body motion ( z ) isconsidered, it can be shown through suitable geometric transformations that the locationerror, Ep, of a point P on the workpiece is reduced by the optimization process surface(see Figure 5). For instance, the location error of the point (30, 100, 19.1) decreases from15.3 m for the initial fixture layout to 11.7 m for the improved layout. Thus, thefixture layout optimization model and solution procedure described above improve workpiece location accuracy by minimizing the effect of workpiece rigid bodydisplacement.Finite Element Analysis. In order to further analyze the effect of the fixturelayout optimization process on overall workpiece deformation a finite element model wasconstructed using ANSYS (version 5.3). The locators were modeled as displacementconstraints that prevent workpiece translation in the normal direction. The clampingforce was modeled as a uniformly distributed force acting over the workpiece-clampcontact area.The deflection of the top surface of the workpiece (i.e., the surface to bemachined) is shown for the initial and improved fixture layouts in Figures 6 and 7,respectively. The initial fixture layout shows a significant deflection gradient across thetop surface of the workpiece. Deflection magnitudes range from 0.25 x 10-4 mm to 0.76 x10-2 mm. In general a large variation in deflection magnitudes is not desirable. On theother hand, the improved fixture layout produces a relatively uniform distribution ofdeflections that range from 0.10 x 10-2 mm to 0.19 x 10-2 mm. The maximum deflectionof the top surface is much less for the improved layout (0.19 x 10-2 mm compared to 0.76x 10-2 mm). Also, the reaction forces at L1 and L2 are 638.05 N and 65.31 Nrespectively for the initial layout, and 327.20 N and 376.16 N respectively for theimproved layout. Thus reaction forces in the improved layout are more uniformlydistributed than the initial layout.Therefore the optimization process produces a fixture layout that improves theoverall workpiece deflection and reaction force characteristics in addition to improvingworkpiece location accuracy.5.ConclusionsThe paper presented a fixture layout optimization model for improving thelocation accuracy of the workpiece when clamped in a machining fixture. Theinaccuracy in workpiece location was due to rigid body motion of the workpieceproduced by the localized elastic deformation at the fixturing points. A discretizedelastic contact model of the fixture-workpiece interaction was used to develop theconstraint equations. Zoutendjiks method of feasible directions was used to solve theresulting nonlinear program. It was shown through model simulations that the workpiecelocation error is minimized by the optimization procedure. In addition, the improvedfixture layout produces a overall workpiece deformation pattern that is more uniform and lower in magnitude. The reaction force distribution among the side locators is alsoshown to be more uniform for the improved fixture layout. The optimization procedurepresented here can be used for fixture planning purposes.中文翻译通过夹具布局优化提高工件的定位精度1导言 精度的定位一加工特征依赖于加工夹具的能力，以精确定位工件相对机床主轴。 工件定位在一个夹具是显着的影响，局部弹性变形工件在装夹点。这些变形是造成夹紧力适用于工件。对于一个相对刚性的工件局部弹性变形的原因，它必须接受刚体翻译和轮换而改变其位置与敬意，向刀具。因此，这是重要的尽量减少这种影响，通过优化设计的夹具布局。以前的工作，在夹具布局优化的重点是使用有限元和刚体模型。 menassa和devries 1 ， rearick等。 2 ， trappey等基地。 3 ，蔡力峰等人 4 用有限元模型夹具-工件系统投入布局优化。在这些工程的夹具布局设计是作为制定约束非线性优化问题。目标是要确定位置定位器钳对，这将最大限度地减少非线性函数的弹性变形选定点对工件。这一提法需要解决的完整有限元模型，在每一次迭代的优化过程。因此， 技术是计算密集。demeter 5 提出了极大极小算法，以确定最佳的夹具布局和夹紧力强度降到最低，最高的接触力。在这研究工件和夹具均假定是完全僵化了。这一提法不容许的影响工件位移定位误差减至最低直接。最近，桂等 6 报道，一种模式，提高工件的定位准确度，通过优化夹紧力。这些模型的弹性夹具接触用线性弹簧已知的僵硬。但是，方法确定接触刚度得不到解决。此外，夹具布局假设固定为某个工件和切削力系统。本文介绍一种方法，即直接最小工件定位误差因局部弹性变形，工件在装夹点最佳把定位器和线夹靠近工件。该方法认为夹具联系，以得到线弹性，并利用封闭形式接触刚度模型来自著名的接触力学问题。此外，该方法在这里概述是高运算密集的少，比有限元方法。 以下各节详细说明的基本模式和限制使用制定夹具布局优化过程。模式模拟提交展示能力的方法，以减少工件的定位误差，通过优化配置，定位和夹紧装置。2夹具布局优化夹具布局的优化，需要制定一个目标函数和制约因素。在本文中，我们的目标是尽量减少的影响，局部弹性变形工件在装夹点，对工件的位置。正如此前，弹性变形造成的工件，要经历一个刚体运动， 这反过来又轮班工件的位置。目标函数为优化构造如下。目标函数的制定工作。考虑了坚实的矩形工件关押在一个夹具构成的几个地点和固定器（见图1 ） 。夹具是典型很僵化，相对于工件。它可以因此假定，这种定位不任何刚体位移。相比之下，一些势力采取行动，工件在定位和夹紧点，造成工件翻译和旋转，在全球坐标系统。假定了刚体运动的工件由于正常和切向弹性变形，在提取装夹点是由载体注意，组成我都表示，在局部坐标系统固定到提取点。几何变换应用，使该刚体议案由于变形，在提取装夹点是表示，在全球坐标体系： 那里的TG 是常用的一项通用旋转矩阵变换的数量表示，在当地提取坐标系统纳入全球坐标系统。因此，总的刚体运动工件因弹性变形，在所有装夹点是： 其中n是总人数的定位和夹紧装置。 为了减少其影响刚体运动对工件的位置， 二次目标函数为夹具布局优化，现在可以写成详情如下： 注意：以上的表达是没有明确功能的夹具元件的立场。 但刚体运动 i的，因此 ，是依赖于装夹势力这又是唯一确定的布局装夹分和弹性接触物业。因此，改变夹具布局，改变了价值的客观功能间接的影响。夹具-工件接触约束。夹具-工件系统是受几次接触的限制，优化夹具布局还必须满足。在特别是制约指明几何相容的弹性变形和摩擦阻力需要。这些制约因素有：开发利用离散弹性联系建模方法相似，即conry和seireg 7 ，并辛哈和Abel 8 。工件假设为弹性，在接触区域和僵化的其他地方。 夹具是被假定为完全僵化了。在每一个装夹点方形联系表面相切夹具和工件表面的假设。接触面是离散成一个网格，载米平方元素如图2所示。分布式正常力量的强度p j 和一个分布式摩擦力的强度假定他们的行为跨越了一个任意元素J号提取的接触面。总正常（ PI ）和摩擦（旗）的部队采取行动，在提取装夹点，是当时特定的： 局部变形，在装夹点原因远点，在工件，要经历一个刚体运动在正常的方向给予 z 。若S j 一最初分离的夹具和工件表面为jth元，在提取装夹点时，正常的变形， WJ通信公司一，必须符合以下条件接触 9 ： 平等标志适用于各点所在内的平衡接触面积和不平等的迹象外点。正交分量的切向变形， uj I和第V j 一，由摩擦力代理在装夹分的领先优势，以切刚体提案 x i y ，分别满足变形和刚体运动应满足以下几何相容条件 9 ： 而平等和不平等的迹象分别出现滑倒和没有滑动的情况。接触变形模型工件。假设为一个线性弹性固体在附近的装夹点。因此，由线性叠加，正常变形，在jth 元素的提取联系地区，可以这样写： 那里有弹性的影响力系数为变形，在正常方向由于装夹势力在正常（ N ）和切线方向（ x ，y ）的。 同样地， X和Y组成部分切变形是由于： 其中受正常和切向弹性的影响系数为工件变形，在本地X和Y方向上提取装夹点，分别为。 在这个文件中的影响力系数均来自封闭形式解联络遵守的一个弹性半空间受到分布式正常切负荷。详细的影响系数模型，可发现在 8,9 。接触摩擦约束。库仑摩擦是假定适用于每一个装夹点。这意味着一种非线性关系正常和摩擦力，在代理1装夹点，即 而 s的是系数静摩擦，为夹具-工件材料一双。为了简洁明了，线性版这一约束的方法有： 静力平衡制约因素。工件必须在静力平衡后， 应用装夹势力在选定点。这一限制是由以下为力和力矩平衡方程： 地方势力和矩表示，在计算该元素的正常性（ P）和切向力（ qxji ， qyji ）代理在接触面为每装夹点。夹紧力的限制。当夹紧力所夹的是特别指明，这是有必要的总和元素正常的力量夹紧点平等指定的力量。这一制约因素表现为如下： 其中c是多少夹在夹具。在这个文件中的夹紧力是假设为众所周知的。在普通不过的夹紧力，可视为一种设计变量在布局优化过程 5 。夹具元件位置的限制。该夹具布局优化过程，旨在为了找到最佳位置的装夹点。一般来说，夹具元件阵地对一个工件基准面表面不能随机选取，并往往受限几何复杂的工件表面，大小和位置的特点，以被加工，以及其他过程有关的问题。因此，立场一夹具元件是仅限于某一区域范围内对基准表面。在本文中，每个夹具元件立场是制约躺在里面凸多边形区域。一个序列的命令直边，代表每一个凸多边形。在数学方面，该系统的线性不平等的兴建，由线方程的所有命令边缘（对N装夹分） ，是用来指定范围内地区：因此：也有：该元素的爱和CI都是系数线方程的多边形边用指定多边形的边界为提取一点，喜的是位置向量（全球）向高于对照组点对工件表面上看，李是多少下令边虚构包围多边形为提取点。上述不平等现象，现在可以用来轻松建立协助寻找一名装夹点相对于其多边形的边界。站内或就边界完全满足上述不等式，而点以外的区域范围内做不 10 。布局优化模型。完整的夹具布局优化问题，可以现正
- 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