Project: WORM & WHEEL REDUCTION GEAR BOX PROJECT
Speed Reduction is obtained by the action of a 'Worm' as it meshes with a "Worm Wheel" or 'Worm Gear' on which are cut teeth of involute profile. The threads on the worm are machined to the proportions of a rack so that worm and wheel engage in the manner of a spur gear and a rack.
In the Gear Box, the worm has 3 threads or 'Starts' and is in effect a 3-toothed gear which engages a 39- toothed wheel so that the speed reduction is 13:1.
The worm is made from Case Hardened Steel and the wheel from Phosphor Bronze, i.e. the teeth are cut on a phosphor bronze ring which is 'SHRUNK' onto a cast iron or steel hub and is further locked by a key.
Bearings & mounting
Both Worm and Wheel are mounted on Taper Roller Bearings.
WORM - 33205 (SKF taper roller bearing) - 2 required
WHEEL - 32210 (SKF taper roller bearing) - 2 required
The Worm & Wheel Gear Box is as shown below:
WORM & WHEEL SPEED REDUCER
Worm Details
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Module (M)
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5
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Pressure Angle
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20°
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Addendum
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ModuleM
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Dedendum
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1.157M
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Pitch Diameter
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35.5
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Outside Diameter
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45.5
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Root Diameter
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23.5
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Axial Pitch
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15.71
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No. of Threads (Starts)
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3
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Lead
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47.13
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Length
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80
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Wheel Details
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No. of Teeth
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39
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Module (M)
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5
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Circular Pitch
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15.71
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Pitch Diameter
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195
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Root Diameter Outside Diameter
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192.5
214.5
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Face Width
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28
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Centre Distance
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120
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Note: Abutment (shoulder of a shaft) is used to locate a bearing. See SKF website for the abutment diameter.
Teacher's expectation of the students:
• All drawings should be drawn in accordance with AS1100
a. All sketches should have sufficient information for a draftsperson to prepare the detail drawings. You can draw them either in Orthogonal (Third Angle) or Isometric Projection.
b. All drawings must follow Australian Standards, in third angle projection, using the correct drawing sheet size and scale. You should use sectional view(s) to show internal details and fully dimensioned on the detail drawings. There is no need to dimension in assembly drawing except those dimensions for controlling the relative position of the assembled parts.
c. All detail drawings should include manufacture information (tolerances, surface finish, etc.). The standard of the drawings should meet the requirements of working drawings. Read Engineering Drawing by A.W. Boundy chapter 9 for more information.
Instructions:
1. Use SolidWorks or Inventor Professional to create the solid model of the Bearing Retainer for 33205 (use Revolve Tool) and save it with a filename 33205 Bearing Retainer.
2. Use Save Copy As to create a copy of the 33205 Bearing Retainer part file, using the filename 33205 Bearing End Cap. Edit the 33205 Beating Retainer file by removing the 025 hole on the sketch to get the solid model for the 33205 Bearing End Cap.
3. Use Save Copy As again to create a copy of the 33205 Bearing Retainer part file, using the filename 32210 Bearing Retainer. Edit the 32210 Bearing Retainer file by changing the dimensions on the sketches to get the solid model for the 32210 Bearing Retainer.
4. Create detail drawings of the two Bearing Retainers.
You should select suitable drawing sheet size for your drawings, using suitable scale and according to Australian Standard. You should add centre lines, fully dimension your drawings and add tolerances wherever necessary. On your drawing, you should also include Information Note like general tolerances, general surface finish, general fillet and chamfer size and material used.
Use component name as filename.
5. Create the solid model for the Housing. For the Housing, you first create a rectangular block and use Shell Tool to change it into a hollow box. Then add the remaining features.
* Important: Ensure you get the dimensions right or you will have trouble during assembly.
6. Create the solid model for the Bearing Carrier.
7. Create an assembly model of the Worm & Wheel Gear Box. Place the Housing first, ground or fix it, and then assemble the Bearing Carrier to the Housing. Note the screw holes should be aligned correctly.
8. Generate the Worm & Wheel (see page 2 for details).
If you are using Inventor: On the Ribbon click the Design tab, use the Worm Gear Tool on Power Transmission Panel to generate the Worm & Wheel. Modify the Wonn according to the sketch you had prepared and the Wheel according to the sketch provided (see page 4). * Important: The Worm & Wheel generated is a sub-assembly, you should edit the Worm and the Worm Gear part files (ipt) and NOT the sub-assembly file (iam).
9. Generate the Worm Wheel Shaft according to the sketch you had prepared.
If you are using Inventor: On the Ribbon click the Design tab, use the Shaft Tool on Power Transmission Panel to generate the Worm Wheel Shaft according to the sketch you had prepared.
10. Continue with the assembly of the worm and wheel gearbox.
a. Open up the assembly file and place the SKF 32210 & 33205 bearings.
If you are using Inventor: See Blackboard on Notes on Using the Content Centre before you place any component from the content centre.
b. Assemble the Worm & Wheel, beatings, keys & the Wonn Shaft together first & then the Bearing Retainers. After that, assemble the whole Wonn & Wheel sub-assembly to the Housing.
c. Add all the fasteners to secure the Bearing Carrier and the Bearing Retainers to the Housing.
(If you are using Inventor: Open the Design Ribbon, use the Bolted Connection Tool on Fasten Panel to add the fasteners)
11. Create an assembly drawing of the Worm & Wheel Gear Box. The assembly drawing should include:
a. A Half Sectional (top half) Front View looking from 'A' to include the Worm Shaft mounting details, engagement of worm and wheel and location of wheel centre.
b. A Full Sectional Side View from 'B'.
Select suitable drawing sheet size and scale for your drawing. Include balloon reference of all the parts and a parts list in the assembly drawing. Make up your part numbers. Material should be specified in the parts list.
12. Generate the detail drawings of the Worm Wheel, Worm Shaft & the Worm Wheel Shaft to AS.
Fully dimension each detail drawing, and add centre lines, surface finish and tolerances. On the drawing, you should also include an Information Note: general tolerances, general surface finish, general fillet and chamfer size and material used. Tabulate the worm wheel details in a table.
13. Select suitable couplings to connect to a) the worm shaft (input) and b) the worm wheel gear shaft (output).
Attachment:- Worm-Wheel-Project.rar