课程教案Teaching Plan7.docx

1、课程教案Teaching Plan7Teaching Plan -7:Sketch Learning OutcomesOn the completion of this unit you will be able to correctly use the following skills as follows: Create a sketch. Identify constraints correctly. AssessmentCompetency will be assessed by operation tasks throughout this section. Please forwa

2、rd the Practical Applications Manual to your supervisor for assessment on completion of operation tasks. ResourcesPractical Applications (Period: 2 classes in classroom)Practical Applications of UG NX4.0（Student Guide）Lesson 7: SketchingOperation (Period: 2 classes in computer training room)Practica

3、l Applications Manual Operation 4: Sketching Key PointCreate and edit a sketch, constraintSketching OverviewA sketch is a collection of two-dimensional geometry within a part. Each sketch is a named collection of 2D curves and points residing on a plane that you specify. Sketcher tools let you fully

4、 capture your design intent through geometric and dimensional relationships that we refer to collectively as constraints. Use constraints to create parameter-driven designs that you can update easily and predictably.When there is a commonly used shape that varies in size, a sketch can easily accommo

5、date the iterations of the design by editing a single constraint.Sketches should be used as base features of a model if the shape lends itself to extruded or revolved geometry.Sketches and the Part NavigatorSketches can be created by choosing the Sketch Section icon in certain feature creation dialo

6、gs such as Extrude and Revolve, choosing the Sketch icon directly in the Form Feature toolbar, or by choosing InsertSketch. Creating a New SketchDefining a Sketch PlaneWhen creating a sketch, you first need to define the plane on which to place the sketch curves. But, you must consider the state of

7、the model. An icon option bar shown below appears in the upper left corner of the graphics window and contains options to define the sketch plane.Naming a SketchSince a unique name is required for each sketch, a default name will initially be assigned with a numeric suffix. The format of the default

8、 name is SKETCH_# where # is replaced by the next sequential three digit number beginning with 000 (SKETCH_000, SKETCH_001, etc.). A sketch name may be defined during or after the sketch has been created by clicking on the default sketch name, typing in the new name and pressing Enter.The Active Ske

9、tch In any given part there may be numerous sketches of different features at different orientations. When using the sketcher, only one sketch may be worked on at a time. This sketch is called the active sketch. Curves created while a sketch is active become associated with the active sketch. When r

10、eturning to a sketch to add to or modify a profile, the sketch must be activated. There are a few ways to activate a sketch: Double-clicking on a sketch curve. In the Part Navigator double-click on the sketch feature node. Choose the Sketch icon and select the desired sketch from the Sketch Name pul

11、l-down.There are also a few ways to deactivate an active sketch: Choose the Finish Sketch icon. Choose SketchFinish Sketch. Activate a different sketch. Choose SketchNew and create a new sketch.Sketch Creation Steps Set the work layer for the sketch. Choose the Sketch icon. Define the sketch plane o

12、n a WCS plane (XC-YC, YC-ZC, or ZC-XC) or create a Datum CSYS at absolute coordinates. Name the sketch. Choose OK. Sketch CurvesSketch curves are created via the Sketch Curve toolbar. As curves are created geometric constraints are assigned to the curves relative to the Infer Constraints Settings.1

13、Profile2 Line 3 Arc 4 Circle Infer Constraint SettingsThe Infer Constraints Settings dialog determines which constraints are automatically created during curve creation. It is accessed by choosing the Infer Constraint Settings icon from the Constraints toolbar or ToolsConstraintsInfer Constraint Set

14、tings.As you create the curves a symbol will appear near the curve being created to represent the constraint that will be applied, if any.Locking a ConstraintWhen a constraint symbol appears during curve creation you may lock in that constraint by pressing MB2. For example, if you are creating a lin

15、e and the parallel symbol appears, press MB2. As you move the cursor, the new line that is rubber banding is doing so parallel to the reference curve.Snap Point ToolbarThe Snap Point toolbar can be displayed when creating most of the curve types in the sketcher so that you have more control over the

16、 selection of locations.When the Snap Point toolbar is active, regardless of the point types turned on, cursor location is always available. Profile ToolThe Profile tool allows creation of a string of lines and arcs without having to specify a start for each curve after the first curve is created. T

17、he Profile tool is turned on by default when you first create a sketch and can be accessed by choosing the Profile icon on the Sketch Curve toolbar. Creating LinesLine creation is accessed by choosing the Line icon on the Sketch Curve toolbar.Once in line creation, the icons in the upper left corner

18、 of the graphics window provide two options: Coordinate Mode (by cursor location or keying in an XC and YC coordinates) and Parameter Mode. Creating ArcsArc creation is accessed by choosing the Arc icon on the Sketch Curve toolbar.Once in arc creation, the icons in the upper left corner of the graph

19、ics window give you two sets of options. The first is creation method, and the second is for the Coordinate/Parameter Mode.There are two different arc creation methods: Arc by 3 Points Locate the start, locate the end, and then locate a point on the arc. Locate the start, enter a radius value and pr

20、ess Enter, locate the end point, and then move the cursor to preview and choose which of the four possible solutions to create. The same as the previous, but enter the radius value after locating the end point, but before the point on arc. Arc by Center and End Points Locate the center, locate the s

21、tart point, and locate the end point. (The start point location determines the radius.) Locate the center, locate the start point, enter a radius value and press Enter, locate the end point. Locate the center, enter radius and sweep angle values and press Enter, locate the start of the sweep, and sp

22、ecify the direction for the sweep. Creating CirclesCircle creation is accessed by choosing the Circle icon on the Sketch Curve toolbar.Once in circle creation, the icons in the upper left corner of the graphics window provide two sets of options. The first is creation method, and the second is for t

23、he Coordinate/Parameter Mode.There are two different circle creation options: Circle by Center and Diameter Locate the center, and then locate a point on the circumference of the circle. Locate the center, enter a Diameter, and press Enter. The circle is created. You are then in multiple circle crea

24、tion mode - just indicate another location for a circle center. Locate the center, drag the radius until you get the size you want. Press Enter. The circle is created, and you are in multiple circle creation mode. Indicate another center. Circle by 3 Points Locate three points on the circumference o

25、f the circle. Locate two points on the circumference of the circle, enter a radius value and press Enter, then choose which of the two options you want by cursor location. Creating FilletsFillet creation is accessed by choosing the Fillet icon on the Sketch Curve toolbar.Once in fillet creation, ico

26、n options appear in the upper left corner of the graphics window. The Trim Inputs option (1) determines whether or not the original curves are trimmed. The Delete Third Curve option (2) determines whether the middle curve is deleted in a three-curve fillet. The Create Alternate Fillet option (3) wil

27、l produce a complementary solution for the fillet (e.g. a 270 degree arc instead of the default 90 degree arc).You can create fillets between lines, arcs or conics. You can also create a fillet between two parallel lines.There are several ways to create Fillets: Select two curves with a single selec

28、tion (at their intersection), and then drag the size and quadrant. Select two curves individually, and drag the size and quadrant. Select one curve, enter a radius value, and select the second curve. Select two curves individually, enter a radius value, and the indicate the desired quadrant. Drag (w

29、ith MB1) across the two curves you want to fillet. The size of the fillet is determined by where the curves are selected.Trimming and Extending Curves Quick TrimThis option will allow you to trim any curve to the closest curve in the sketch and preview the results in preselection color. You can trim

30、 multiple curves at one time, by using the crayon select method.Hold down MB1 and drag across the portion of curves you want to trim away.You can select a specific curve to trim to, by using Ctrl-select to select the desired boundary curve. More than one bounding curve can be selected using this met

31、hod.When a curve is trimmed, appropriate constraints are automatically created. In the previous example, two Point on Curve constraints and one Collinear constraint are added. If one of the boundary curves is later trimmed to the line, the Point on Curve constraint would change to Coincident.If you

32、trim an arc to a line that is tangent, the tangency constraint is retained. Quick ExtendThis option will extend lines, arcs and conics to the closest curve in the sketch. The system will preview the results in the preselection color.The curve being extended must extend to an actual intersection with the boundary curve.You can extend multiple curves at