Advanced Modeling Techniques Sweep and Helical Sweep

Transcription

1 Advanced Modeling Techniques Sweep and Helical Sweep

2 Sweep A sweep is a profile that follows a path placed on a datum. It is important when creating a sweep that the designer plans the size of the path accordingly in order for the profile to make a turn. Notes Sweeps can be used to add or subtract material. Examples of Sweeps: Exhaust on a car, any type of tubing, 1. Creating the Path a. Select the Model Tab > Sketch Icon > Front Datum b. Draw the following path (note the path is an open profile. Users can make closed paths to create a solid Shape. NOTE Path does not have to be exact measurements like what is displayed c. Green Check out of the profile when finished.

3 d. Select Model Tab > Sweep e. If the Path Sketch is not selected, select the Path Sketch Line from the workspace or from the model tree. This will highlight the Path in green showing the Origin (Start point of the Object). If the user wanted to change the starting point, simply select the arrow at the origin and it will flip to the other endpoint of the path f. Click the Sketch Icon in the Sweep Info Bar g. This will rotate the user perpendicular to the Starting Endpoint h. Drawing a Circle that is a diameter of 0.50 at the start of the path Click Green Check to Exit Sketcher i. The profile should be following the path. j. Edit your Sketch Click on the sketch icon again What happens if you sketch inside the original sketch profile or next to it?

4 Helical Sweep Helical Sweeps allow the user to sketch a profile and rotate it around an axis Examples: Springs, External Threads 1. Spring a. Select Model Tab > Select the Black Arrow next to the Sweep Icon > Select Helical Sweep b. First thing we will draw is the length of the Spring a. Select References from the Info Bar > Select Define (Helical Sweep Profile) >Select Front Datum >Sketch > This will place you in the sketcher b. Draw a centerline along the Right Datum (Vertical Reference) c. Draw a vertical line (This line represents the overall length of the spring) d. Set the following Dimensions Place Centerline Value represents the diameter of the pitch line in relation to the axis. Depending on where the designer places the profile will change the overall shape of the object. (Note our profile will be centered on the endpoint) e. Green Check to exit

5 f. Select the Sketch Icon from the Helical Sweep Info Bar g. This will place you in the sketcher. Draw a circle that is a diameter of 0.25 at the base of your pitch line h. Set the pitch The pitch is the distance between the center of one coil to the center of the next. Enter a value of in the Helical Sweep Info Bar i. Preview will show up. Try changing the pitch to What Happens?

6 j. Select the Pitch Tab > Select Add Pitch > Change End Pitch to.1 Notice how the pitch on the spring changes as it goes from start to end k. Click Add Pitch a second time > Change pitch to.3 and Location 2 (Location represents where the new pitch will take over along length of the spring l. Add one more change in pitch value to your spring. May adjust current settings (Diameter of coil, Start, End Pitches, etc)

7 Assignment Create New Part with the following Path Sketch to the following Curve. (References Tab > Define)

8 Helical Sweeps- External Threads Helical Sweeps can be used to cut in detailed threads on a cylinder or a hole cut. When creating threads the designer should always cut in the threads. Thread Measurements Note: All threads are Right Handed unless stated LH at the end of the measurement Major Diameter Threads per Inch 3/8 16 UNC 2 A or B Class of Fit: 1, 2, or A = External Thread B = Internal Thread Thread Series: I.E UNC, UNF, ACME, etc. Step 1: Design Cylinder to cut into a. Design a cylinder that is a Diameter of and length of 4.00 inches. Place the circler face of the cylinder on the Top Datum. The Cylinder represents the major Diameter of the thread. b. Chamfer: Add a chamfer at the end of the blank cylinder where the threads will start Chamfer Size D x D =.05

9 Step 2: Setup the length of thread c. Select the Model Tab > Black Arrow next to the Sweep Icon > Select Helical Sweep > Select the Reference Tab > Define > Select the Front Datum d. Place a Centerline to revolve around at the center of the cylinder e. Select References Tool > Select the Left Vertical Edge of the Cylinder f. Draw a Vertical Line Starting from the Top Datum on the Referenced edge. Change the Height of the line to 3.00 inches. Length of Thread (Pitch line): Drawn on the edge of the cylinder. Centerline to revolve around g. Green check to accept the values Start Length of thread at the top Reference line

10 h. Select the Sketch Icon on the Helical Sweep i. The Thread Profile should always start on the outside of the hole or cylinder you are about to cut into and touching the start point. The thread profile will be a triangle that has angles of 60 degrees and the pitch. (Pitch= 1/Threads per Inch). Draw the following profile. Thread Start Point CHANGE TO Pitch = 1/13 All Interior Angles = 60 Degrees j. Green Check to accept the sketch k. Set the Pitch Value in the Helical Sweep Profile. NOTE: This pitch must be a little bit bigger than the actual pitch of the threads so intersection of the threads does not occur. Set the Pitch Value to.08 l. Select the Cut Icon to cut the threads m. Green Check to accept the cut

11 n. Create the bolt head of the threaded feature. Use the Drafting and Design Textbook Reference Charts in the appendix part of the book or the Machinery Handbook to find the size of the bolt head. Note the bolt head size is based upon the Major Diameter of the thread. Helical Sweep- Internal Threads 1. Design the Nut a. Design the following hexagon. Note the sizes are based upon the Major Diameter of the thread. These measurements can be found Reference Construction Circle: Measured Across the Corners of the Hexagon. Secondary way to measure is across the flats, which is measuring from one flat face to the parallel face. Use Equal Length Constraint to make sure all sides of the hexagon are the same. b. Extrude Distance c. Green Check to accept

12 d. Revolve Cut in the Chamfer with following Measurements. Be sure to select a datum that passes through the corners of the hexagon and not the flats. 2. Drill the hole that is to be tapped with a thread. a. When drilling this hole the designer must drill the hole to the Minor Diameter and then cut in the major Diameter. Formula for Calculating Minor Diameter Minor Diameter = Major Diameter (1.300/ Total Threads per Inch) b. Drill a hole to the minor Diameter at the center of the Hexagon with a thread measurement of ½-13UNC-2B

13 3. Create a Helical Cut of the thread. NOTES - Thread Length should be longer than the hole, so be sure to extend the length of the thread (helical sweep profile) beyond the end of the hole. - Be sure to think about your starting point and which way the threads will match up to the bolt threads. - Set the Pitch in the Info Bar a little bigger than the actual pitch (The Values are the same as the bolt including the Triangle- Angles and Pitch Value are the same as the Bolt) FINAL PART Challenge Assemble the bolt and nut. Try and line up the threads. Hint: Create a section of the parts and figure the offset distance.