第10章_AutoCAD2010_参数化绘图

AutoCAD 2010中文版参数化绘图
122 4.1.1 设计要求
首先根据产品的设计要求对产品的整个设计进行分析，如图4-2所示。

图4-2 设计要求
前道设备落料到传送带上，经传送带传递到下一台设备。

要在传送带和下一台设备之间加一个合适的传送装置，并且能够方便地调节高度和位置，以满足设备的各种需求。

4.1.2 草绘和尺寸驱动
1. 设置绘图环境。

(1) 设定绘图区域的大小为2 000×2 000。

双击鼠标中键使绘图区域充满整个图形窗口。

(2) 通过【线型控制】下拉列表打开【线型管理器】对话框，在对话框中设定线型的全局
比例因子为0.1。

(3) 打开极轴追踪、对象捕捉及捕捉追踪功能。

设置极轴追踪角度增量为90°，设定对象
捕捉方式为“端点”、“中点”、“圆心”及“交点”。

2. 绘制大体的轮廓。

(1) 打开附盘文件“4-1.dwg ”，如图4-2所示，其形状和位置均已固定。

(2) 选用【常用】选项卡，执行绘圆命令绘制图形，结果如图4-3所示。

图4-3 常规方法绘制的图形。

AutoCAD2010基础知识讲解图形是表达和交流思想的主要工具，随着计算机科学技术的不断发展，绘图工作早已由传统的手工绘图转换为计算机辅助绘图，利用计算机绘图是当今工程设计人员必须掌握的基本技术，而AutoCAD就是专门为计算机绘图开发的设计软件。

使用该软件不仅能够将设计方案用规范、美观的图纸表达出来，而且能有效地帮助设计人员提高设计水平及工作效率。

本文主要介绍AutoCAD 2010软件界面组成、菜单操作方法、基本功能和部分新功能，以及管理图形文件和设置绘图环境的方法和技巧。

本章学习要点：【菜单浏览器】按钮位于界面左上角。

单击该按钮，将弹出AutoCAD菜单，如图1-8所示。

该菜单中包含AutoCAD 2010图形文件基本操作全部命令，用户选择选项后即可执行相应操作。

2.快速访问工具栏AutoCAD 2010的快速访问工具栏中包含最常用操作的快捷按钮，方便用户使用。

在默认状态中，快速访问工具栏中包含多个快捷按钮，默认显示的按钮有【新建】、【打开】、【保存】、【打印】、【放弃】和【重做】按钮，可根据需要在展开的菜单中设置显示或隐藏按钮。

如果想在快速访问工具栏中添加或删除其他按钮，可以右击快速访问工具栏，在弹出的快捷菜单中选择【自定义快速访问工具栏】选项，在弹出的【自定义用户界面】对话框中进行设置即可。

3.标题栏标题栏位于应用程序窗口的最上面，用于显示当前正在运行的程序名及文件名等信息，如果是AutoCAD默认的图形文件，其名称为DrawingN.dwg(N是数字)。

单击标题栏右端的按钮，可以最小化、最大化或关闭应用程序窗口。

标题栏最左边是应用程序的小图标，单击它将会弹出一个AutoCAD窗口控制下拉菜单，可以进行最小化或最大化窗口、恢复窗口、移动窗口、关闭AutoCAD等操作。

标题栏位于AutoCAD 2010窗口界面的最上方。

在标题栏中除了显示当前软件名称，还可显示新建的或打开的文件名称等。

浅谈AutoCAD2010参数化功能贵州省经济学校向啟苗摘要：在计算机教学工作中，AutoCAD2010版新功能之一，参数化约束，发现界面极有个性，功能强大，操作快捷、简便，弥补软件的不足，特写此文，与大家共同学习和探索。

关键词：AutoCAD2010 新功能参数化几何标注管理约束参数化是AutoCAD2010的一项新功能，AutoCAD 2009及以前的版本是没有参数化约束功能的，然而参数化功能并不是什么新名词，其实在很多图形软件（如3DMAX等）中早就使用了参数化功能，因此，AutoCAD因为软件竞争的关系，在AutoCAD2010版引入了参数化功能。

这样对于AutoCAD使用人员来说，大大方便了大家的绘图操作。

那么AutoCAD2010参数化功能到底给用户绘图带来哪些方便，增添了哪些功能，作者就参数化功能谈谈个人的看法。

一、认识参数化参数，也叫参变量，是一个变量。

当我们在研究某一问题的时候，关心某几个变量的变化以及它们之间的相互关系，其中有一个或一些叫自变量，另一个或另一些叫因变量。

如果我们引入一个或一些另外的变量来描述自变量与因变量的变化，引入的变量本来并不是这一问题必须研究的变量，我们把这样的变量叫做参变量或参数。

参数化（parameterization）就是通过一组变量建立某种对应的关系。

在AutoCAD2010中引入了参数化建模和参数化设计。

所谓参数化建模就是通过一组参数来约定几何图形的几何关系和尺寸关系。

何谓参数化设计（Parameric Design）又称变量化设计是美国麻省理工学院Gossard教授提出来的，参数化设计通常是指软件设计者为绘图及修改图形提供一个软件环境，设计人员在这个环境下所绘制的任意图形均可以被参数化，修改图中的任一尺寸，均可实现尺寸驱动，引起相关图形的改变。

参数化设计的突出优点在于通过变更参数的方法来修改设计意图。

二、AutoCAD2010参数化功能AutoCAD2010参数化管理界面由三个部分组成，几何、标注和管理，几何就是几何约束，标注指的是尺寸约束，管理是对参数化进行管理。

AutoCAD2010基础教程AutoCAD 2010 基础教程阅读43897人图形是表达和交流思想的主要工具，随着计算机科学技术的不断发展，绘图工作早已由传统的手工绘图转换为计算机辅助绘图，利用计算机绘图是当今工程设计人员必须掌握的基本技术，而AutoCAD就是专门为计算机绘图开发的设计软件。

使用该软件不仅能够将设计方案用规范、美观的图纸表达出来，而且能有效地帮助设计人员提高设计水平及工作效率。

本文主要介绍AutoCAD 2010软件界面组成、菜单操作方法、基本功能和部分新功能，以及管理图形文件和设置绘图环境的方法和技巧。

本章学习要点：熟悉AutoCAD 2010软件工作环境熟悉AutoCAD 2010软件的基本功能和新增功能掌握管理图形文件的方法了解绘图环境的设置方法掌握坐标系的定义方法1.1计算机辅助设计与AutoCAD简介计算机辅助设计作为工程设计领域中的主要技术，在设计、绘图和协作方面已经展示了其强大的技术实力。

工程技术人员可使用AutoCAD迅速而准确地绘制出所需要的图形，特别是AutoCAD强大的编辑功能、符号库和二次开发的功能，使其在建筑、机械和电子等领域得到了广泛的应用。

1.1.1计算机辅助设计计算机辅助设计（Computer Aided Design，CAD）是20世纪60年代发展起来的一门新兴学科，目前已经成为现代工业设计中十分重要的一项技术。

而AutoCAD系列软件以其便捷的绘图功能、友好的人机界面、强大的二次开发能力以及可靠的硬件接口，已经成为了世界上应用最广泛的CAD软件之一。

1．计算机辅助设计的概念计算机辅助设计这个概念是一个不断发展变化的概念。

在计算机应用的初级阶段，人们将其理解为计算机辅助设计，即利用计算机来解决大量繁琐的计算，使设计人员能够将更多的精力投入到算法和方案解决上。

然而，由于AutoCAD软件的普及和发展，在最近几年人们逐渐转变了观念，并对其进行重新定义，即计算机辅助设计是一种将人和计算机的最佳特性结合起来以辅助进行产品设计和分析的技术，是综合了计算机与工程设计方法的最新发展而形成的一门学科。

A Practical Guide to Parametric Drawing in AutoCAD Rick Ellis – Cadapult Software Solutions, Inc.Parametric design tools aren’t just for programs like Inventor software, Revit software, or AutoCAD Civil 3D software; there is also a set of parametric drawing tools that you can use to create dynamic relationships and constraints between objects in AutoCAD software. The parametric drawing tools will revolutionize the way that you draw and edit objects in AutoCAD software. This class will introduce you to parametric drawing in AutoCAD software by using both geometric and dimensional constraints to add intelligence to your objects. You will learn how using Auto Constrain and Inferred Constraints can help you quickly add constraints and change your process from drafting to modeling. If you’ve ever wanted geometry in your drawing to update based on changes that you’ve made to other objects, or if you’ve wanted to type a new value into a dimension and have the object update based on this new value, this class is for you.Learning ObjectivesAt the end of this class, you will be able to:1. Learn how to create geometric relationships between objects by adding constraints2. Learn how to define dimensional constraints3. Learn how to identity and edit constrained objects4. Learn how to use inferred constraints to have AutoCAD automatically define constraints for you Your AU ExpertsRick Ellis is the President of CADapult Software Solutions, Inc., where he provides training and consulting services to clients around the country, helping them get the most out of their design software investment. Rick specializes in AutoCAD® Civil 3D®, AutoCAD® Map 3D, Autodesk® InfraWorks™, AutoCAD® Raster Design, and AutoCAD®. He is a member of the Autodesk Developer Network, and author of several critically acclaimed books on AutoCAD Civil3D, and AutoCAD Map 3D; including the Practical Guide series. Rick continues to use AutoCAD Civil 3D on projects in a production environment, in addition to teaching classes to organizations both large and small around the country. This practical background and approach has made him a sought after instructor by organizations around the world.**************************@theRickEllisOverviewWhat is parametric drawing?The Autodesk Definition: “Feature in AutoCAD that assigns constraints to objects, establishing the distance, location, and orientation of objects with respect to other objects.”If the defini tion above didn’t answer all of your questions about parametric drawing, I’ll expand on that and go into a bit more detail. AutoCAD 2010 introduced Parametric drawing. This is not only a relatively new feature for AutoCAD, it is a new concept that will change the way that you create and edit drawings in AutoCAD. While this is a somewhat new feature for AutoCAD, similar tools for parametric design have been in other products like Inventor, Revit, and Civil 3D for some time and you may be familiar with them. Put simply, the idea of parametric drawing is that objects can be related to each other. For example, if you want two lines to be parallel, they would always be parallel. If you change one line then the other will update to match it. This is just one example. However, if you think about all the possibilities, and all the time that you have spent editing drawings to make sure that all the necessary and related changes have been made for a simple change to the design, these tools have the potential to revolutionize the way that you work.AutoCAD uses two types of Parametric Constraints:▪Geometric Constraints∙The Autodesk Definition: “Rules that define the geometric relationships of objects (or points of objects) elements and control how an object can change shape or size.Geometric constraints are coincident, collinear, concentric, equal, fix, horizontal, parallel,perpendicular, tangent, and vertical.”∙Sticky Object Snaps. They maintain the geometric relationship between objects rather than setting it once at the time you use the object snap and then allowing it to change inthe future.∙Add intelligence to your drawings.∙Allow you to think more about modeling and less about drafting.▪Dimensional Constraints∙The Autodesk Definition: “Parametric dimensions tha t control the size, angle, or position of geometry relative to the drawing or other objects. When dimensions are changed, theobject resizes.”∙You can type the value into a dimension and the object updates. It’s the opposite of associative dimensions. With Dimensional Constraints the dimension value drives thegeometry rather than the geometry driving the dimension.∙Can include equations.∙Can even reference other objects. For example, line 1 is twice the length of line 2.Exercise 1 – Working with Existing Constraints1. Open the drawing Widget Assembly complete.dwg from the folder called Completed Assemblyin the dataset.2. Select the block representing the slider on the shaft (identified by callout number 2).3. Move the block.4. Notice the block can only move along the shaft and the arm rotates as it moves.5. Double click the dimension d1 and change the value to 1.56. Notice that changing the value of the dimension moves the block.7. Select and move one of the callouts.8. Notice the entire row of callouts moves together.9. Try moving other pieces of this assembly to see the different constraints in action.10. Open the drawing Parametric - geometric.dwg from the dataset.11. Move and stretch different pieces of the orthographic projection to see how constraints have beenset up within it.Geometric ConstraintsGeometric Constraints maintain the geometric relationship between objects based on basic geometric properties of the entity or entities you apply them to. AutoCAD supports the following geometric constraint types:▪Coincident▪Co-linear▪Tangent▪Perpendicular▪Parallel▪Horizontal (relative to the current UCS X axis)▪Vertical (relative to the current UCS Y axis)▪Concentric▪Equal▪Symmetric▪Smooth▪FixedThe commands to create and manage Geometric Constraints can be found on the Parametric tab of the ribbon.The table below shows the types of objects that can be used to create geometric constraints and their constraint points.Tips when creating geometric constraints:▪When applying constraints between two entities AutoCAD modifies the second entity selected, leaving the first entity unmodified.▪If you convert an object that has constraints to a ployline the constraints are lost.▪If you explode a polyline that has constraints the constraints are lost.▪If you copy an object with constraints the constraints are copied if all the objects involved in the constraint are copied.Constraint BarsConstraint Bars provide a heads-up interface to help you manage geometric constraints in your drawings. Constraint Bars look and behave a lot like transparent floating tool bars, except that each button on a bar represents a single geometric constraint.When you place your cursor over individual constraints on a constraint bar AutoCAD highlights the button, the entity the constraint applies to, and the corresponding button and entity participating in the constraint.When you right-click on a constraint on the constraint bar there are several commands which you can perform on the constraint, including deleting the constraint, hiding the bar, or managing the constraint bar settings.To delete all constraints on an entity use the Delete Constraints command. Ribbon: Parametric tab >> Manage panel >> Delete Constraints.Exercise 2 – Working with Geometric Constraints1. Open the drawing Parametric - geometric.dwg from the dataset.2. Pan to a blank area of the drawing.3. Draw 4 individual lines similar to the graphic below.4. Add Geometric Constraints to make this a dynamic rectangle.a. Use the Coincident, Parallel, and Perpendicular constraints.5. Zoom extents to find the bracket in the drawing as displayed below.6. Add Geometric Constraints to make the bracket hinge at the corner while keeping both sides ofthe part the same size.7. Zoom extents to find the orthographic projection.8. Copy the orthographic projection.9. Remove all the constraints from the orthographic projection.10. Add geometric constraints to the orthographic projection to make it behave as the original.Auto ConstrainIf applying geometric constraints one at a times seems like a tedious task there is an option to let AutoCAD look for objects that can be constrained and add them for you. Auto Constrain examines entities you select and attempts to automatically constrain the geometry based on its current position.You can control the settings for the Auto Constrain command in the Constraint Settings dialog box. Ribbon: Parametric tab >> Geometric panel >> >> Constraint Settings.Here you can select the type(s) of constraints that you want the Auto Constrain command to apply. You can also set Tolerances for distance and angle. These tolerances will determine if constraints are applied and objects are modified when they are “close” to geometrica lly accurate. When used properly this can help clean up a drawing that was created without using object snaps. However, you want to choose your tolerances carefully as it will allow the Auto Constrain command to modify geometry. If you only want the Auto Constrain command to apply constraints where the geometry is perfect and not modify any geometry, set the tolerances to 0.Inferred ConstraintsInferred constraints automatically apply geometric constraints while creating and editing geometric objects, removing the need for you to add constraints later. The Infer Constraints mode works with your object snaps and is enabled with a toggle on the status bar.Once enabled object snaps that are used when creating or editing objects are also used to infer geometric constraints. Objects are not modified by inferred constraints.Exercise 3 – Working with Auto Constrain and Inferred Constraints1. Open the drawing Parametric – Inferred.dwg from the dataset.2. Pan to a blank area of the drawing.3. Draw a rectangle using the rectangle command.4. Use the Auto Constrain command to add constraints.5. Notice what constraints are added.6. Zoom extents to find the bracket in the drawing as displayed below.7. Use the Auto Constrain command to add constraints.8. Notice what constraints are added.9. Turn on Inferred constraints.10. Draw a rectangle using the rectangle command.11. Notice what constraints are added.Dimensional ConstraintsDimensional Constraints constrain objects by allowing you to enter values or formulas. They work similar to associative dimensions, just in reverse. While associative dimensions update the value of the dimension as the object changes, dimensional constraints update the object when the value of the dimension changes. The dimensions drive the geometry rather than the geometry driving the dimensions. Dimensional constraints come in the following types:▪Aligned▪Horizontal▪Vertical▪Radial▪Diameter▪AngularDimensional constraints can constrain the following properties:▪Distances between objects, or between points on objects▪Angles between objects, or between points on objects▪Sizes of arcs and circlesThere two different kinds of dimensional constraints:▪Dynamic∙Maintain the same size regardless of zoom level∙Can easily be turned on or off globally in the drawing∙Display using a fixed, predefined dimension style∙Position the textual information automatically, and provide triangle grips with which you can change the value of a dimensional constraint∙Do not display when the drawing is plotted▪Annotational∙Change their size when zooming in or out∙Display individually with layers∙Display using the current dimension style∙Provide grip capabilities that are similar to those on dimensions∙Display when the drawing is plottedIf you need to control the dimension style of dynamic constraints, or if you need to plot dimensional constraints, use the Properties palette to change dynamic constraints to annotational constraints.The commands to create and manage Dimensional Constraints can be found on the Parametric tab of the ribbon.Tips when creating dimensional constraints:▪When applying dimensional constraints AutoCAD modifies the constrained geometry to satisfy the new constraint.▪If you convert an object that has constraints to a ployline the constraints are lost.▪If you explode a polyline that has constraints the constraints are lost.▪If you copy an object with dimensional constraints the constraints are copied.▪Dimensional constraints can contain equations.The example above contains a rectangle with two basic dimensional constraints.The example above contains a rectangle with two dimensional constraints where the length (d1) is equal to twice the height (d2).You can manage all the values of your dimensional constraints with the Parameters Manager. Ribbon: Parametric tab >> Manage panel >> Parameters Manager.In the Parameters Manager you can edit expressions and even add user defined variables that you can use in expressions.Exercise 4 – Working with Dimensional Constraints1. Open the drawing Parametric - dimensions.dwg from the dataset.2. Zoom to the rectangle.a. It already has geometric constraints.3. Add Dimensional Constraints for the width and length.4. Edit the width to be 3.5. Edit the length to be twice the width by editing the expression.6. Zoom extents to find the bracket in the drawing as displayed below.a. It already has geometric constraints.7. Add a dimensional constraint to control the angle.8. Draw circles at each end of the part.9. Use a concentric geometric constraint to position them10. Add a dimensional constraint that makes them half the outer radius of the part.Constraints in Dynamic BlocksIntroduced in AutoCAD 2005, Dynamic Blocks extend the capabilities of traditional blocks by providing the ability to define custom grips and properties for your blocks which affect the geometry for the block. You create dynamic blocks by combining Block Actions and Block Action Parameters within the block definition. Now you can extend the power of blocks even further by adding geometric and dimensional constraints to your dynamic blocks.When you add geometric and dimensional constraints to dynamic blocks it is best to add them in the block editor using the commands on the Block Editor tab of the Ribbon.A Block Properties table allows you to define and control values for parameters and properties within a block definition. This will become the list of selectable values in the dynamic block.Exercise 5 – Working Constraints in Dynamic Blocks1. Open the drawing Parametric - blocks.dwg from the dataset.2. Open the block editor.a. Ribbon: Insert tab >> Block panel >> Block Editor.b. Name the new block AUParametric.3. Draw a rectangle using the rectangle command starting the lower left corner of the rectangle at0,0.4. Add Geometric Constraints to make this a dynamic rectangle.5. Add Dimensional Constraints for the width and length.6. Edit the width to be 5.7. Edit the length to be twice the width by editing the expression.8. Add a Block Table.a. Place the block table near the origin of the block.b. Placement of the block table does not need to be exact. It will be the location of a grip onthe block that can be used to select standard sizes.9. Enter 1 for the number of grips.10. Click the Add Properties button11. Select the d1 parameter and Click <<OK>>.12. Enter values for d1 as shown above.13. Click <<OK>> when finished.14. Close the block editor and save the changes.15. Insert the block anywhere in your drawing.16. Select the block and notice the available grips.a. You will be able to stretch it in the vertical direction and the rectangle will keep the 2:1ratio of length to width.b. Select the block table grip and you will see the predefined widths.c. Select one of the values and notice how the block resizes.ConclusionParametric drawing in AutoCAD with geometric and dimensional constraints is a powerful set of tools that may drastically change the way that you create and edit drawings. I hope that this introduction to these exciting features has got you thinking about ways that you can apply it to your own drawings and projects.I encourage you to try it out, start small at first, but I am confident that you fill not only find these tools a powerful time saver but also intuitive and easy to learn.。