Tutorial 6-6 Fan Blade Model - Oakton Community College · 6 Title of the Project or Textbook 8....
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Chapter XX Chapter Title Goes Here 1 Tutorial 6.6 Fan Blade Model Learning Objectives After completing this chapter, you will be able to: • Create 3-dimensional objects using INTERSECTION. • Create complex 3D objects using UNION and SUBTRACT. • Create and use multiple VPORTS. • Use Universal Coordinate System to create constant and variable VPORTS. • Use Universal Coordinate System to create and modify 3D objects. In this real-world example, a manufacturer of fans experienced a problem. Motorized fans used in household refrigerators were failing due to excessive vibration. It was discovered that plastic fan blade assembly was not balanced. A new design was needed. The fan blade assembly created in this exercise solved the vibration problem. In the first stages of this construction, we will create the 2D profile of the blade, using the same techniques as were used by the manufacturer. After creating the profile, we will create an INTERSECTION with a cylinder to give the blade a curved cross-section. Finally, we will ROTATE the cylinder to adjust the blade’s angle of attack. In the next stages, we will create the three cylinders that will become the hub. We will SUBTRACT them in the correct order, we will create the hub. We will then ARRAY the fan blade around the hub and UNION the entire assembly. In the final steps, we will create the off-center, D-shaped keyway used to transmit the rotation from the motor to the fan blade assembly. Because this keyway is off-center, it must be placed within the assembly in such a position that it maintains the symetrical center of gravity of the fan-blade assembly. We will use the MASSPROP command to find the center of mass of the fan-blade assembly and of the D-shaped keyway. Using this information, we will MOVE the keyway to the center of mass of the fan-blade assembly. Once this keyway is in position, we will SUBTRACT it from the assembly to create the keyed hole in the hub.
Transcript of Tutorial 6-6 Fan Blade Model - Oakton Community College · 6 Title of the Project or Textbook 8....
Chapter XX Chapter Title Goes Here 1
Tutorial 6.6
Fan Blade Model Learning Objectives
After completing this chapter, you will be able to: • Create 3-dimensional objects using INTERSECTION. • Create complex 3D objects using UNION and SUBTRACT. • Create and use multiple VPORTS. • Use Universal Coordinate System to create constant and variable VPORTS. • Use Universal Coordinate System to create and modify 3D objects.
In this real-world example, a manufacturer of fans experienced a problem. Motorized fans used in household refrigerators were failing due to excessive vibration. It was discovered that plastic fan blade assembly was not balanced. A new design was needed. The fan blade assembly created in this exercise solved the vibration problem.
In the first stages of this construction, we will create the 2D profile of the blade, using the same techniques as were used by the manufacturer. After creating the profile, we will create an INTERSECTION with a cylinder to give the blade a curved cross-section. Finally, we will ROTATE the cylinder to adjust the blade’s angle of attack.
In the next stages, we will create the three cylinders that will become the hub. We will SUBTRACT them in the correct order, we will create the hub. We will then ARRAY the fan blade around the hub and UNION the entire assembly.
In the final steps, we will create the off-center, D-shaped keyway used to transmit the rotation from the motor to the fan blade assembly. Because this keyway is off-center, it must be placed within the assembly in such a position that it maintains the symetrical center of gravity of the fan-blade assembly. We will use the MASSPROP command to find the center of mass of the fan-blade assembly and of the D-shaped keyway. Using this information, we will MOVE the keyway to the center of mass of the fan-blade assembly. Once this keyway is in position, we will SUBTRACT it from the assembly to create the keyed hole in the hub.
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Figure 1-4. The Completed Fan Blade Assembly
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Creating a Fan/Blade Assembly
Creating a 2D Fan Blade: In the first stages of this construction, we will build a fan blade. We will begin by
creating the 2D profile of the blade, using the same techniques used by the manufacturer. These techniques include the creation of Endpoint-Endpoint-Radius Arcs and the use of Fillets to create smooth transitions.
Figure 2: The 2D Fan Blade
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Step 1 – Create the Profile of the Fan Blade
1. Create Layers as shown. Make the Fan layer current.
Name Color Linetype Fan Black/white Continuous Center Red Center Construction Black/white Hidden
2. Create one CIRCLE centered at 0,0 with a radius of 1.65-inches
3. Create a concentric CIRCLE centered at 0,0, with a radius of 5-inches.
4. After making the Center layer current, create a LINE from 0,0 to the 12 0’clock quadrant of the 5-inch circle.
5. After making the construction layer current, create three Lines, as follows:
a) LINE 1 from 0,0 to @5<59
b) LINE 2 from 0,0 to @5<121
c) LINE 3 from 0,0 to @5<142
Figure 3: Circles and lines
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6. Trim the Circles as shown.
Figure 4: Trimmed circles
7. Create an endpoint-endpoint-radius ARC with a radius of 5-inches on the Fan layer, as shown.
Figure 5: Create Arc 3
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8. FILLET the two 5-inch arcs with a radius of .375-inch.
Figure 6: Filleted Arcs
9. Create a 2-point CIRCLE with a radius of .375-inch aligned with the 142-degree line, as shown.
Figure 7: Create .375-inch circle
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10. TRIM the circle using the 142-degree line.
Figure 8: Trim circle
11. Create an endpoint-endpoint-radius ARC with a radius of 2, as shown.
Figure 9: Create a 2-inch radius arc
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12. Fillet the trimmed arc to the 5-inch arc with a radius of .375-inch.
13. Freeze the construction layer.
Figure 10: Trimmed Arc
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Create a 3D Fan Blade In this stage, we will use the 2D fan blade to create a 3D, solid fan blade. We will
create a pair of large cylinders that completely enclose the profile. We will then subtract the two cylinders to create a “pipe” with a wall thickness of 0.065-inch. We will then EXTRUDE the profile to completely penetrate the pipe. We will make the fan blade by creating the INTERSECTION of the extrusion and the pipe. In the last step, we will ROTATE the fan blade to modify the angle of attack.
Step Two – Create a 3-Dimensional Fan Blade
14. Use the VIEWPOINT command to obtain a SW Isometric view.
15. Using the POLYEDIT command, join the arcs into a single Polyline.
Figure 11. Edited Polyline
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16. Using the Vports command, create two vertical Viewports.
17. Open the Tools pull-down menu.
18. From New UCS select X-Axis.
19. Rotate the X-Axis through 90-degrees.
20. Create a CYLINDER with its center at 0,0 a radius of 12 and a height of -6 inches.
21. Create a second Cylinder with its center at 0,0 a radius of 11.935 and a height of -6 inches.
Figure 12: Cylinders
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22. ZOOM in to see the two concentric cylinders.
23. SUBTRACT the smaller cylinder from the larger one.
Figure 13: Subtract cylinders
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24. Activate the first Viewport, which we will call VPort-1.
25. Extrude the fan blade profile with a height of 13-inches and a taper of 0.
Figure 14: Extrude blade profile
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26. Create the INTERSECTION between the cylinder and the extruded blade profile. This is the Fan Blade
Figure 15: Create the 3D Fan Blade
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27. Activate the second Viewport, Vport-2.
28. Move the 3D Fan Blade from its present position to a Y value of Zero.
Command: MOVE
Select Objects: (pick the fan blade)
Select Objects: ↵
Specify base point or displacement: @
Specify Second Point of displacement: @0,-11.935,0
Figure 16: Fan Blade moved to y-Axis equals zero.
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29. Rotate the 3D Fan Blade, using the Center line as an axis, through an angle of 12-degrees.
Figure 17: Rotated Fan Blade
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Creating the Hub of the Fan/Blade Assembly In this step, we will create the hub of the fan/blade assembly. We will create three
cylinders. We will create them of such a size and position them in such a way that we will create a hollowed outer cylinder with a central cylindrical hub.
Step Three – Create the Hub
30. Activate VPort-1
31. Create a CYLINDER with a center at 0,0,-.75, a radius of 1.75 and a height of 1.5-inches
32. Create a second CYLINDER with a center of 0,0,-.5, a radius of 1.5 and a height of 1.25-inches
33. Create a third CYLINDER with a center of 0,0,-.75, a radius of .5 and a height of 1.5-inches.
Figure 18: Create Three Cylinders
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34. SUBTRACT the middle cylinder from the largest.
35. UNION the newly created assembly and the smallest cylinder.
Figure 19: Hub Assembly
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36. ARRAY the 3D Fan Blade to make five blades evenly spaced around the hub.
37. UNION the five Fan Blades and the hub to make the fan/blade assembly.
Figure 20: The Fan/Blade Assembly
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Creating the Key for the Fan/Blade Assembly In this step, we will create a D-shaped object. We will extrude this object to create
the key. This key will be used in the next step to create the keyway in the fan/blade assembly’s hub.
Step Four – Create the D-Shaped Object
38. Activate VPort 1.
39. Create a CIRCLE slightly above the fan/blade assembly with a radius of 0.375-inch.
Figure 21: Create a circle
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40. Draw a LINE from the center of the circle to the 12 o’clock quadrant.
41. Turn Ortho on.
42. Draw a LINE from the midpoint of the radius beyond the circumference of the circle at 0-degrees.
43. Draw a LINE from the midpoint of the radius of the circumference of the circle at 180-degrees.
Figure 22: Create the construction lines.
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44. TRIM the circle and the lines.
45. POLYEDIT the remaining lines and arc to create a closed Polyline.
Figure 23: D-shaped Polyline
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46. EXTRUDE the polyline to a height of 3-inches with a taper angle of zero. This is the Key that we will use to create the Keyway in the hub of the Fan/Blade Assembly.
Figure 24: Extruded polyline.
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Creating the Keyway in the Fan/Blade Assembly In these steps, we will move the center of the Key to the center of the assembly. We
will use MASSPROP to observe that the center of mass of the Key is not at the center of its central arc. When the center of the keyway is placed at the geometric center of the of the Fan/Blade Assembly, the slight difference in the centers of mass creates the imbalance. This imbalance, although small, will become significant after approximately one year of continuous operation. We will move the center of mass of the Key to the center of mass of the Assembly before we SUBTRACT it to create the completed Fan/Blade Assembly.
Step Five – Complete the Fan/Blade Assembly
47. Move the Key from the center of its bottom arc to 0,0,0.
48. Activate VPort 1.
49. Use the MASSPROP command, located in the Inquiry section of the Tools pull-down menu, to confirm that the center of mass of the Fan/Blade Assembly is as shown below:
Figure 25: Mass properties of Fan/Blade Assembly
---------------- SOLIDS ---------------- Mass: 11.7863 Volume: 11.7863 Bounding box: X: -4.9973 -- 5.0067 Y: -4.9513 -- 5.0002 Z: -1.5179 -- 0.7500 Centroid: X: 0.0000 Y: 0.0000 Z: -0.1613 Moments of inertia: X: 45.6330 Y: 45.6332 Z: 86.0129 Products of inertia: XY: 0.0059 YZ: -0.0004 ZX: 0.0004 Radii of gyration: X: 1.9677 Y: 1.9677 Z: 2.7014 Principal moments and X-Y-Z directions about centroid: I: 45.3207 along [0.7134 0.7008 0.0000] J: 45.3325 along [-0.7008 0.7134 0.0000] K: 86.0129 along [0.0000 0.0000 1.0000]
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Although this step isn’t necessary, we have used the MASSPROP command to determine the location of the center of mass of the Fan/Blade Assembly. As shown, the center should be where X and Y equal 0 and the Z is approximately -0.16-inches. The volume of the assembly should be about 11.79 cubic inches.
50. Move the Key from the center of the bottom to 0,0,0.
51. Use the MASSPROP command to determine the center of mass of the Key, as shown.
Figure 26: Mass Properties of Key - Concentric with Cylinder
---------------- SOLIDS ---------------- Mass: 1.0663 Volume: 1.0663 Bounding box: X: -0.3750 -- 0.3750 Y: -0.3750 -- 0.1875 Z: -0.5000 -- 2.5000 Centroid: X: 0.0000 Y: -0.0642 Z: 1.0000 Moments of inertia: X: 1.8938 Y: 1.9066 Z: 0.0685 Products of inertia: XY: 0.0000 YZ: -0.0685 ZX: 0.0000 Radii of gyration: X: 1.3327 Y: 1.3372 Z: 0.2536 Principal moments and X-Y-Z directions about centroid: I: 0.8231 along [1.0000 0.0000 0.0000] J: 0.8404 along [0.0000 1.0000 0.0000] K: 0.0641 along [0.0000 0.0000 1.0000]
This step is important, because it tells us the location of center of mass of the Key
itself. Notice that, although the X-Axis of the Key is at zero, the Y-Axis is offset by 0.0642 inches. Although this doesn’t seem like much, this slight difference between the center of the arc of the Key and the center of its mass, it is sufficient, over time, to destroy the bushing of a low-cost motor.
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We must move the Key so that the X,Y of its mass is at the same location as the X,Y of the Fan/Blade Assembly. Notice that the location of the center of mass on the Z-Axis is unimportant.
52. MOVE the Key along the Y-Axis by 0.0642-inches.
53. Use MASSPROP to ensure that the X,Y-Axis of the Key is at 0,0, as shown.
Figure 27: Mass properties of Key – after Centering of Mass.
---------------- SOLIDS ---------------- Mass: 1.0663 Volume: 1.0663 Bounding box: X: -0.3750 -- 0.3750 Y: -0.3108 -- 0.2517 Z: -0.5000 -- 2.5000 Centroid: X: 0.0000 Y: 0.0000 Z: 1.0000 Moments of inertia: X: 1.8894 Y: 1.9066 Z: 0.0641 Products of inertia: XY: 0.0000 YZ: -0.0001 ZX: 0.0000 Radii of gyration: X: 1.3312 Y: 1.3372 Z: 0.2453 Principal moments and X-Y-Z directions about centroid: I: 0.8231 along [1.0000 0.0000 0.0000] J: 0.8404 along [0.0000 1.0000 0.0000] K: 0.0641 along [0.0000 0.0000 1.0000]
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54. SUBTRACT the Key from the Fan/Blade Assembly.
55. Use the MASSPROP command to determine if the assembly is centered at X=0 and Y=0, as shown.
Figure 28: Mass Properties of Completed Fan/Blade Assembly
---------------- SOLIDS ---------------- Mass: 11.3419 Volume: 11.3419 Bounding box: X: -4.9973 -- 5.0067 Y: -4.9513 -- 5.0002 Z: -1.5179 -- 0.7500 Centroid: X: 0.0000 Y: 0.0000 Z: -0.1725 Moments of inertia: X: 45.5585 Y: 45.5515 Z: 85.9862 Products of inertia: XY: 0.0059 YZ: -0.0004 ZX: 0.0004 Radii of gyration: X: 2.0042 Y: 2.0040 Z: 2.7534 Principal moments and X-Y-Z directions about centroid: I: 45.2244 along [0.8699 -0.4933 0.0000] J: 45.2107 along [0.4933 0.8699 0.0000] K: 85.9862 along [0.0000 0.0000 1.0000]
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Figure 29: Final Fan/Blade Assembly
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Congratulations! You have created a complex, ACIS-solid assembly. You have used all three Boolean operators, namely UNION, SUBTRACT and INTERSECTION. You have created an object that is symmetrical about its axis of rotation, using the MASSPROP command. You used two VPORTS, each with a different UCS.
However, it is still difficult to view the different parts of this assembly. Just for fun, you might try to change the colors of the fan blades and the different components of the hub assembly using the SOLEDIT commands. Then, use the different SHADE commands along with 3DORBIT to view your assembly. © By downloading this document you agree to the following: Educators only may use this material for educational purposes only at an accredited high school or college. As an educator, you may copy this document as many times as you need for your classroom students. You may not distribute, publish, modify, display, email/transmit to others, and create other similar works from this document, in any way. Any other use of this document is strictly prohibited. Disclaimer: This tutorial is designed for educational purposes only. It is not to be used for manufacture of parts, drawings or assemblies or merchandising of products. The author or publisher shall not be liable for any damages, in whole or part, from the use of this tutorial and its materials or any revisions of this tutorial or materials.
