how to model spur gear in cad

7/21/2019 How to Model Spur Gear in CAD

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20/8/2014 How to model spur gear in CAD

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HOWTOMODELSPURGEARINCAD

This topic explains how to model a spur gear in Pro engineer and Creo without gear

relations except for the involute curve.

Normally the following parameters are enough to manufacture a spur gear.

1. Number of Teeth

2. Module

3. Pressure Angle

4. Width

All other necessary parameters like pitch circle dia, root dia, base circle diameter etc. are

derived by standard set of gear formulas using these values.

But sometimes the manufacturer may have changed some of the values of a gear pair to

satisfy his own requirement. In this case, a table containing all the parameters is placed in

the gear drawing. This data is used to manufacture the gear. The job of the Cad modeler

will be to create the gear model using these values.

Lets see how to model the gear using the data given in the table (see left). To model the

gear completed using gear formulas read here.

You can download the gear drawings from the Downloads-Cadpage.

There are two cases. The root diameter can be larger than the base diameter or the base diameter may be larger than root

diameter. There are some changes in modeling the two cases. We will see that one by one.

Root diameter is larger than base diameter (see table):

1. Make a circle with 149.70 (Root diameter) and extrude it for 50 mm (Width).

2. Create three circles in the front face of the gear blank and name it in the model tree.

Pitch diameter - 156, Base diameter - 146.59, Outer diameter - 167.4
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3. Create a new coordinate system at the center of the gear blank using the datums and front face as shown in the image. Name

it GEAR_CSYS for reference purpose. Make sure that the Z direction points outside, X horizontally and Y vertically. I recommend

to crate it as shown in the image (X and Y in positive direction). This coordinate will be used to create the involute curve from

equation.

Front view

4. Now the involute curve has to be created. In

ProE wildfire versions, go to Insert Model

datum Curve or use the short cut button.

This will open up the curve menu manager. Click

on From equationand Done. Now you have to

select the newly created GEAR_CSYS

coordinate. Then select Cartesian. This will

open the text window.

In Creo, type Curve in the search box at the

top right corner and select Curve from

equation from the list.

Now paste this equation in the text window.

Note: 146.59 is the base diameter.

Base_Rad = 146.59/2

Angle = t*90

Cir_len = (PI * Base_Rad * t ) / 2

X_Pnt = Base_Rad * cos(Angle)

Y_Pnt = Base_Rad * sin(Angle)

X = X_Pnt + ( Cir_len * sin(Angle))

Y = Y_Pnt - ( Cir_len * cos(Angle))

Z = 0

5. Create a sketch for circular tooth thickness (6.28 - see table) at pitch diameter from the intersection point of involute curve

and Pitch diameter as shown in the video..

Save the text window and close. Click done. This will create the involute curve.


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Page Turning Softwareaxmag.com

aXmag, Turn your pdf file into page turning effect magazine6. Come out of the sketcher. Crate a new point at the center of the

circular tooth thickness curve using point option. To do that, go to

Insert Model datum Point point. Now click the newly created

curve and enter 0.5 in the input area as shown in the image.

7. Create a new datum using the point created in step 6 and the

center axis of the gear as shown in the image. This will be used to

mirror the involute curve.

8. Mirror the involute curve using the datum created in step 7.

9. Create a extrude for a single teeth. Use the two involute curves and the outer diameter and base diameter for the sketch.

Trim all other entities. Extrude the sketch to the next face.
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Read More Help T opics Here

9. Create the chamfer and radius.

10. Group the Extruded teeth, chamfer and the radius in the model tree.

11. Pattern this group using the center axis of the gear. 39 teeth (No. Of teet h) for 360 degrees.

12. Add center hole, key way cut and chamfer to the teeth side faces. T hats it we have a spur gear now.

To model gear with Base diameter larger than Root diameter. Next Page

Multiple methods can be used to model the gear. Just understand the concept. You can also do it on your own way combining

the steps.
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Taiwan Gear Manufacturergear-manufacturing.com/

Manufacturer of Spur / Helical Gear, Worm / Bevel / Pinion / Pump gear.
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