cad绘图基本（Basic cad drawing）

1、cad绘图基本（Basic cad drawing）12, three-dimensional grid (3dface): This method is too impractical (slightly)The entity model is the easiest three-dimensional model to use. Using the entity model of AutoCAD, three-dimensional objects can be created by creating rectangular, cone, cylindrical, sphere, wedg

2、e and torus entity models. These shapes are then merged to find their difference or overlap (overlapping) parts, combining to produce more complex entities. You can also create an entity by extending a two-dimensional object along a path or by rotating it around the axis. With Mechanical desktop, yo

3、u can also define parameterized entities, preserving the association between three-dimensional entities and the two-dimensional views that are generated from it.Warning！ Because three-dimensional modeling can construct three-dimensional models in different ways, and each editing method has different

4、 effects on different models, it is recommended that you do not use the modeling method in a mixed way. There can be only limited conversions between different model types, from entities to surfaces or from surfaces to wireframe. However, you cannot convert from a wireframe to a surface, or from a s

5、urface to an entity.13, Rotary surface (Revsurf) Rev: Constructs a polygonal grid that is approximate to a revolved surface by rotating the path curve or section (Straight, Circle, arc, ellipse, elliptical arc, closed multiple-segment, polygon, closed spline, or ring) around the selected axis.14, tr

6、anslation surface (Tabsurf): a surface that is made up of a initial lines (the beginning of the surface) along the specified vector (the length of the initial edge translation).Note: The translation surface can be interpreted as a predefined initial trajectory curve (straight, arcs, circles, spline

7、curves, two-dimensional multiple-segment lines, three-dimensional multiple-segment lines) are translated (stretched) along a stretched trajectory of a specified distance and direction (the surface and the trajectory line remain two different entities).15, Straight line curve (Rulesurf): Refers to tw

8、o lines or curves specified by the relative two sides, by these two sides generated by a three-dimensional grid of the surface, the surface in the two relative lines or curves between the grid is a straight line.1 The curves used to create straight-grain surfaces can be straight lines, points, arcs,

9、 circles, spline curves, two-dimensional multiple-segment lines, and three-dimensional multiple-segment lines, and different entities can also be grouped together.2 The style density of the straight grain surface is determined by the system variable SURFTABL1 and SURFTABL2.System variables SURFTAB1

10、and SURFTAB2 system variables control the grid density (number of tessellation) in M and n direction respectively between 2 and 32766.16, Boundary curve: After determining the 4 edges of the surface, and then through the 4 edges to generate the surface (the 4 edges used to generate the surface must

11、be the end-to-end closed graph.) The curve as the edge can be straight line, arc, multiple segments, etc.).Note: (1) 3DMESH create three-dimensional polygon mesh.(2) Edgesurf creates a three-dimensional polygonal grid of approximate cons patches.(3) Pface creates a three-dimensional mesh with vertex

12、 vertices.(4) Revsurf creates a revolved surface by rotating the path curve or section around the selected axis.(5) Tabsurf creates a translation surface polygon mesh by path curve and directional vector.Eight, view toolbar.Entity descriptionAn entity object represents the volume of an entire object

13、.In all kinds of three-dimensional models, the entity information is the most complete and the least ambiguous. The more complex entity shapes are easier to construct and edit than wireframe and grids.There are three ways to create an entity:1, according to the basic entity form (cuboid, cone, cylin

14、der, sphere, ring body and wedge body) to create the entity;2, stretch two-dimensional objects along the path to create the entity;3. Create an entity by rotating two-dimensional objects around the axis.After you create entities, you can create more complex entities by combining these entities. Thes

15、e entities can be merged to obtain their difference or overlap (overlapping) portions, and the entities can be further refined by rounding, chamfering, or modifying the color of the edges. Because you do not need to draw new geometries or perform Boolean operations on entities, it is easier to manip

16、ulate the faces on the entity. For more information, see Creating composite entities. AutoCAD also provides commands for cutting entities into two parts and obtaining two-dimensional sections of the entity (see modifying three-dimensional entities). As with the grid, the entity appears as a wirefram

17、e before it is hidden, shaded, or rendered.The physical characteristics (volume, inertia moment, center of gravity, etc.) of the entity can be analyzed, the data of the entity object is exported to the NC milling machine for use or fem (finite element method) analysis, or the entity is decomposed in

18、to a grid and a Wireframe object. The Isolines system variable controls the number of element lines used to display the curved part of the wireframe. Facetres System Variables Adjust the smoothness of the shading and blanking objects.IX. Entity toolbars: (Entity objects represent the volume of an en

19、tire object)There are three ways to create an entity:1. Create an entity based on the basic solid shape (cuboid, cone, cylinder, sphere, torus, and wedge):Click on the command, enter the value, click on the view, click the coloring.2, stretching the two-dimensional object along the path,3), or rotat

20、e the two-dimensional object around the axis.1. Create cuboid Box:2, create the sphere (sphere): With this method to draw the ball, the entity is in the form of wireframe to display, wireframe density by the system variable Isolines control, the initial value of the variable is 4, the larger the val

21、ue of the line box more dense.3. Create cylindrical body (Cylinder)4. Create cone (cone)5. Create wedges (Wedge)Note: The wedge form created by this command is long, wide, and high, which is parallel to the 3 axes, and can only be changed by using the 3D Edit command.6. Create a ring (Torus)Note: th

22、e diameter or radius of the ring refers to the diameter or radius of the centerline of the torus.7. Create stretch (extrude) Ext: Create an entity by adding thickness, specifying a height value and inclination, and stretching the object along the specified path. Stretching is especially useful for o

23、bjects that contain rounded corners, chamfer angles, and other details, otherwise it is difficult to replicate these details if they are not on a section.1 The objects that can be stretched and closed are: Many segments, polygons, rectangles, circles, ellipses, closed spline curves, ring and surface

24、 fields.2 objects that cannot be stretched include objects within the block, multiple segments with intersecting or transverse segments, and multiple segments that are not closed (a multiple-segment line should contain at least 3 vertices but not more than 500 vertices).3 below are the steps to stre

25、tch along the path:(1) Input command: Ext(2) Select the object you want to stretch, right-click(3) Input P (path)(4) Select the object that is the path.Note: A two-dimensional entry must be a face field once.8. Create a rotation (Revolve) Rev: Rotates a two-dimensional graphic around a specified axi

26、s to form a three-dimensional entity (rotatable closed multiple-segment lines, polygons, circles, ellipses, closed spline curves, ring-and-surface fields).1 The three-dimensional entity generated by the rotation of two-dimension graphics is also represented by grids, and the grid density is controll

27、ed by the system variable Isolines.2) (the object contained in the block, a multiple-segment line with intersecting or self intersecting segments, which cannot be rotated)9, Cut (slice) SL: Cut the existing entity, and then remove the specified part to generate a new entity (half or all of the profi

28、le can be retained). The split entity retains the layer and color attributes of the original entity.Note: The default method for the split solid is to specify a shear plane at three points, then specify the portion to be retained, or to define the clipping plane by other objects, the current view, t

29、he z-axis, or the XY, YZ, and ZX planes.10, Cutting (section) SEC: After cutting the effect is the entity, and cutting the effect is the surface (surface).11. Interference (Interfere) creates a three-dimensional composite entity (equivalent to the intersection of Boolean operations) with the common

30、parts of two or more three-dimensional entities1), Input command Interfere2), click on the Object3), right key4), click on the next object5), right button.12, set graphics (Soldraw) slightly13, set the view (Solview) slightly14, set configuration (Solvprof) slightlyX. Entity editing toolbarNote: Boo

31、lean operation: in three-dimensional drawings, complex entities are often not generated at once, generally by the relatively simple entity through the Boolean operation combination. Boolean operation is to a number of three-dimensional entities to find and, the difference, the intersection of the op

32、eration, so that they are combined, the final form of the user needs the entity (Boolean operations on the three-dimensional entity is also applicable to the two-dimensional surface, but the surface and wireframe can not be Boolean operation)1, and set (Union) Uni: Merge two or more than two entitie

33、s into a single entity (you can merge entities that are not in the same area or space).2, Difference set (Subtract) Su: Subtracts another entity from one entity and eventually obtains a new entity.1 input command: su2) (Select objects in order) first select the object to be retained, right3) Select

34、the Subtracted object and the right key.Note: The retarded entity and the entity as the meiosis must have a public part.3, Intersection (INTERSTCT) in: Calculates the overlap area of two or more existing faces, the volume of the public portion of two or more existing entities, leaving the public par

35、t and deleting non-public parts.4, stretch surface: stretch the face of the selected three-dimensional entity object to a specified height or stretch along a path (multiple faces at one time).1 when stretched at the specified height and tilt angle, the slope of the stretching can only be between 0-9

36、0 degrees, and the entities that use the surface stretching will return to the original entity and the two as a whole.2 when stretched by stretching path, the stretched path cannot be tangent to the contour of the extruded surface (the stretch path can be straight, circular, arc, elliptical, ellipti

37、cal, multiple, or spline) the stretching path cannot be in the same plane as the face, nor can it have a high curvature portion.The extruded surface is stretched from the section plane and ends at the end of the path and the section perpendicular to the path. An endpoint of the stretch path should b

38、e on the profile plane, otherwise the AutoCAD system will automatically move the path to the center of the section.If the path is a spline curve, the path should be perpendicular to the section plane and one endpoint should be on the section plane. If the path does not have a vertical section, AutoC

39、AD Rotates the cross section until it is vertical. If an endpoint is on a section, the section rotates around this point, otherwise AutoCAD moves the path to the section center and rotates the section around the center.3 input positive values can be stretched along the positive direction (usually ou

40、tward), and a negative value can be stretched along the negative direction (usually in the inline).(The extrude in the Entity toolbar is used to position two-dimensional graphics, and the drawing in the Entity editing toolbar is used to stretch three-dimensional objects)5. Moving surface (Solidedit)

41、: Moves the faces of the selected three-dimensional entity objects along the specified height or distance (one can select multiple faces at a time, and if all the selected moving surfaces are moved across the entity).Note: When a moving surface is the outer surface of an entity, the movement of the

42、surface is essentially equivalent to the surface stretching (the surface movement is not simply moving the solid surface, it is a process of the solid regeneration).6, offset surface: Evenly offset by specified distance or by specified point.Note: 1 The offset (value) is determined by the positive a

43、nd negative direction of the surface, and the direction of the surface to increase the area of the entity is offset (outward) and vice versa.2 When a surface is moved, the adjacent surface must be displaced at the same time.7, remove the surface: not all the physical surface can be deleted, can be d

44、eleted on the surface of the entity include: the internal surface of the entity (that is, the surface of the hole inside the solid), round and reverse angle.For example: if the surface of the hole in the entity is removed, the essence is to fill the hole.8. Rotating surface: Rotating one or more sur

45、faces or parts of an entity around a specified axisNote: Only the inner surface of the entity can rotate, and the outer surface of the entity cannot be rotated.9, tilt Surface: In accordance with the specified direction and angle of the tilt.Note: The tilt angle must be between 90-90 degrees; the di

46、rection of the tilt is determined by the selected base point and the Order of the 2nd (along the selected vector) (base axis). The positive angle will tilt the selected surface and the negative angle will tilt outward.10. Copy face: Copy the surface as a face field or body (the copied surface cannot

47、 be boolean operation).11. Coloring Surface: Modifying the color of the solid surface.Note: When the physical surface is modified to a certain color, the wireframe of the surface will also change to the color that is being given.12, copy Edge: Copy three-dimensional edge (all three-dimensional solid

48、 edges are copied to a straight line, arc, circle, ellipse or spline curve).13, Edge Coloring: Modify the color of the edge.Note: 11, 12, 13, 14 are surface piece operation.14, Imprint: In the selected object embossed an object.Note: 1 The mark on the three-dimensional entity essentially does not ch

49、ange its original shape and volume, but adds or depicts some graphics on its surface. Once a target is carved into a three-dimensional entity, the two become a whole.2 The target graph of the mark must be coplanar with one or more surfaces of the three vertebral entities; and the imprint operation i

50、s limited to the following objects: Arc, Circle, Straight line, two-dimensional multi-segment line, ellipse, spline curve, surface area, body and three-dimensional entity.15. Purge: Deletes shared edges and those vertices that have the same surface or curve definition on the edge or vertex. Remove a

51、ll redundant edges and vertices, embossed and unused geometries.16, segmentation:? You can split a composite entity into parts. A combination of three-dimensional entity objects cannot share a common area or volume. After a three-dimensional entity is partitioned, separate entities retain their laye

52、rs and original colors. All nested three-dimensional entity objects are split into the simplest structure. Note: A Boolean object with a single volume cannot be divided into separate three-dimensional entity objects with unconnected bodies,To split a composite entity into a separate entity1 Choose E

53、ntity Edit split from the Modify menu.2 Select a three-dimensional entity object.3 press ENTER to complete the command.Command line Solidedit17, Shell: Suction shell Use the specified thickness to create an empty thin layer. A fixed thin layer thickness can be specified for all surfaces. The selecti

54、on surface can be excluded from the shell. A three-dimensional entity can have only one shell. AutoCAD creates a new face by shifting an existing surface out of its original position. Specifies that the positive value begins to draw the shell from outside the circumference, and the negative value be

55、gins to draw from within the circumference.19, check: Verify the three-dimensional entity object is a valid ACIS entity, this option is independent of the Solidcheck setting.Xi, Coloring toolbar: (for two-dimensional does not work)1, two-dimensional wireframe: Use lines and curves to represent bound

56、aries when displaying objects. Raster and OLE objects, lines, and line widths are visible2, three-dimensional wireframe: the use of lines and curves to represent boundaries when displaying objects. Displays a shaded three-dimensional UCS icon. Raster and OLE objects, line styles, and linewidth are n

57、ot visible.3), blanking: Displays the object represented by the three-dimensional wireframe and hides the straight line that represents the back face. (Invisible objects can be hidden from sight and eyes)4), plane coloring: After coloring, become the effect of the entity.5), body coloring: After col

58、oring, the effect is more than a flat color shading.6, with a border of the plane coloring: the flat shading and wireframe options are used together. Objects that are shaded by a plane will always be displayed with a border.7, with border entity coloring: Use the body coloring and wireframe options together. Objects that are shaded by the body will alw