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Product Designing using TDD

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This section makes the second chapter of tutorials and is given as a sample. You can download the CAD models for practice from the links in right menu.

In this chapter we will go through the basic steps of developing consumer products using Top-down design (TDD) methodology. 

In today’s world, consumer products are more and more stylish and ergonomic. This requires the use of complex curves and surfaces. So you should have good knowledge of curve and surface building techniques to be a good designer for aesthetically pleasing products. In the following exercises, we will show step-by-step procedure for creating all features so basic knowledge of surface and solid modeling should be sufficient.

We will use the basic tools for top-down design that we learned in the previous chapter.  The focus of the exercises, covered in this section, is the good understanding of the top-down design methodology.  Here we will emphasize the top-down design “concept” and not the “tools” that Pro/E offers. In this way the reader will develop a strong interest in this design approach and will follow the remaining chapters vigorously. 

In the following exercises we will use the Internal Copy Geometry Feature to communicate data from skeleton to the individual components. Although we can use the External Copy Geometry Feature instead of Internal Copy Geometry with same end results but here we will not go into discussion of, what are the benefits of External Copy Geometry over Internal Copy Geometry Feature. You should concentrate on the core top-down design concept. In the later chapters you will see why External Copy Geometry is preferred over Internal Copy Geometry feature. Then if you want you can easily convert the Internal Copy Geometry Features to External Copy Geometry features.

In TDD process the term Split Surface is often used. Here it means the surface where two components of a product join. It is different from the splitting surface (or parting surface) while creating the tooling of a molded or casted component.

While designing products with non-planar split surface, it becomes necessary to begin with split surface. This will be shown in the following exercises.

EXERCISE 1

In this exercise we will create a plastic product consisting of three parts. The completed product is shown below.

 

 

 

The common attributes between TOP and BOTTOM parts are as follows

1.    Profile of both components is same.

2.    Both components join along a 3-D surface

The common attributes between TOP and LED COVER parts are as follows

1.    Profile of LED COVER and accommodating cut in the TOP part is same.

2.    The outer shape of both parts follow a common surface

 

So we will create the geometry in the skeleton model that controls the above common attributes.

Only, the geometry that affects or crosses more than one component (or has to be referenced by more than one component) should be placed in the skeleton.

Set the working directory to PHONE folder and open the assembly PHONE.ASM

Notice that there are three components assembled with Default constraints. Also notice that all components have only default datum features as shown below.

 

 

Skeleton model is already defined. We will add the required geometry in it.

 

  Building the Skeleton

Open the skeleton model PHONE_SKEL.PRT in a separate window and notice that it consists of datum curves as shown below.

 

 

The white rectangular curves represent the horizontal and vertical boundaries of the phone assembly. These curves are sketched just to facilitate dimensioning and constraining of other features.

Now we will create a surface that represents the top of the product and will be shared by the TOP and LED COVER components.  

Pick  icon to invoke the variable section sweep tool.

Notice that system is asking to select the trajectory, so pick the following curve.

 

 

Pick  tab to open the References slide-up panel.

Change the “Section plane control” option to Normal To Projection.

 

 

Appearance of the References slide-up panel will change as shown below.

 

 

Notice that “Direction reference” collector is now active. So select SKL_TOP datum plane as direction reference.

 

 

System projects the Origin Trajectory along the selected references (SKL_TOP Datum Plane in this case) and the section plane stays normal to this trajectory as the section is swept along the trajectory.

Pick  and select the end points of BOUNDARY_PROFILE datum curve as references as elaborated in figure below.

 

 

Sketch two centerlines that pass through selected references as shown below.

 

 

Pick  and sketch an arc as shown below.

 

 

We have aligned the end points of the arc to the centerlines just to make sure that the surface generated will intersect with other features that lie within the part boundaries.

Pick  after completing the sketch.

Pick  icon to complete the Variable Section Sweep feature. The surface will appear as shown below. This new surface will be called as “top surface”.

 

 

Normal To Projection option makes sure that the surface does not overlap or intersects itself and hence there is no manufacturing problem for the final components using this surface as reference.

Now we will create another surface that will be used to split the TOP and BOTTOM parts (in other words, the surface at which both these components join).

Pick  icon to invoke the variable section sweep tool.

Pick the following curve as reference.

 

 

Pick  tab and change the “Section plane control” option to Normal To Projection.

Select SKL_TOP datum plane as direction reference.

Pick  and select the end points of BOUNDARY_PROFILE datum curve as references as elaborated in figure below.

 

 

Sketch two centerlines that pass through selected references as shown below.

 

 

Pick  and sketch an arc as shown below.

 

 

Pick  after completing the sketch.

Pick  icon to complete the Variable Section Sweep feature.  This new surface will be called as “split surface”.

Before proceeding, first blank the boundary curves by hiding the SKL_CURVE_BOUNDARY layer. (Pick  icon to access layer tree)

 

  Communicating the Design Information

In this exercise we will create two Publish Geometry features in the skeleton model.

Click Insert > Shared Data > Publish Geometry.

 

 

The Publish Geometry dialog box will appear. As the surface collector is active so pick the split surface as shown in figure below..

 

 

Pick in the Chain collector to activate it as shown below.

 

 

Now select the following two curves (highlighted) while holding down the Ctrl key.

Note: These curves are named MAIN_PROFILE and INTERLOCK_LIP in the model tree.

 

                    

 

All the selected references (chains) will appear in the Published Geometry dialog box as shown below.

 

 

Pick  to apply the changes and exit the dialog box.

To create the second publish geometry feature again click Insert > Shared Data > Publish Geometry.

 As the surface collector is active so pick the top surface as shown in figure below.

 

 

Pick in the Chain collector to activate it and select the following highlighted curve.

 

                     

 

Pick  to apply the changes and exit the dialog box.

Now we will create Copy Geometry features in individual parts. These Copy Geometry features will reference the Publish Geometry features created in the skeleton part. We will create the Copy Geometry feature in the assembly environment so make the assembly window PHONE.ASM active.

First we will create a copy geometry feature in the PHONE_bottom.prt

Right-click the PHONE_bottom.prt in the model tree and select Activate.

 

 

Click Insert > Shared Data > Copy Geometry.

The Copy Geometry dashboard will appear. Notice that Publish Geometry reference collector is active by default. So select the first publish geometry feature in the skeleton part, by picking it in the model tree, as shown below.

 

 

Pick  to apply the changes and exit the dashboard.

Now right-click the PHONE_top.prt in the model tree and select Activate.

We will create two copy geometry features in this part.

Click Insert > Shared Data > Copy Geometry.

As Publish Geometry reference collector is active so select the first publish geometry feature in the skeleton part as shown below.

 

 

Pick  to apply the changes and exit the dashboard.

Notice that the PHONE_TOP is still active so again click Insert > Shared Data > Copy Geometry.

Select the second publish geometry feature in the skeleton part.

 

 

Pick  to apply the changes and exit the dashboard.

Now right-click the PHONE_LED_COVER.prt in the model tree and select Activate.

Click Insert > Shared Data > Copy Geometry.

Select the second publish geometry feature in the skeleton part.

 

 

Pick  to apply the changes and exit the dashboard.

 

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Quick Links

Pro/MOLD Tutorials

Pro/NC Tutorials

Surface Modeling Tutorials

Top-Down Design Tutorials


Downloads

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Models for Wildfire 4.0

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