Patterns are one of the most powerful functions that Pro/ENGINEER offers to its users. Of the many ways to duplicate a feature, patterns are the most effective, flexible and quickest.

This article focuses on table-driven patterns. Using the table option of the pattern, you can create a pattern of features where the spacing between instances of the pattern is not consistent. Creating a pattern through a table also lets you define as many tables as necessary, and changing the table changes the pattern per the values in the corresponding table.

For example, say you have to design a rectangular plate with a set of slots on its face, and the number of slots and spacing between them vary based on the height of the plate. To meet the intended design requirement of the slots, you can create a pattern of slots driven by the table and add the tables to create varying configurations of slots for different heights of the plate. But whenever the height is modified, it is your job to set a corresponding pattern table for the slots.

This technique explains how to instruct Pro/ENGINEER to pick the right table automatically based on the change in, say a dimension or parameter; thus, eliminating the need for human intervention and hence the possibility of error. This can be achieved by linking pattern tables to the height of the plate via another powerful feature of Pro/ENGINEER—namely, Relations.

Here are two situations where this technique proves to be extremely useful:

• When the model is designed using Pro/PROGRAM, to make the system automatically pick up the right table based on user’s input of certain dimensions or parameters. This also seems to be an effective means for setting a particular pattern table in a PROGRAMed part.
• When a family of instances is to be created, there is no need to add the pattern table to the family table.

Here is a step-by-step process for driving a table-driven pattern through relations..

1. Create the base feature.

Create a solid protrusion with a rectangular section that is 48” high, 15” wide, and 0.20” thick.

Figure 1. Base feature

2. Change the dimension symbol.

Using PART, Modify, DimCosmetics, Symbol, change the symbolic name of the dimension representing height of the base feature to HEIGHT.

3. Create an extruded solid cut, which is going to be PATTERNed.

Create a cut feature.

• Choose Feature, Create, Cut.
• Choose Done to accept the Extrude/Solid.
• Choose Done to accept the attribute of One side.

Define the sketching plane.

• Select FRONT datum plane as the SKETCHING PLANE.
• Choose Okay.

Define the reference orientation plane.

• Choose Top.
• Select the TOP datum plane.

Create the sketch shown in Figure 2 to be used as the Cut profile.

Figure 2. Profile of the cut feature.

Select Thru Next when prompted for the Depth of the feature. Finish the feature creation by clicking OK in the FEATURE DEFINITION dialog.

4. Pattern the slot.

Choose Feature, Pattern.

Select the Cut feature created in step 3.

Choose Done.

Choose Table.

Select the dimension representing distance between center of the slot and edge of the rectangular plate as the Driving dimension for the pattern.

Figure 3. Selecting the driving dimension.

Choose Done.

Choose Add.

Enter SLOTS_48H as name of the pattern table (Figure 4).

Figure 4. Name of the pattern table

You should see the Pro/TABLE editor as shown in the image below. Enter the value for the driving dimension for the other members of the pattern (Figure 5).

Figure 5. Pro/TABLE editor.

Save the Table and exit the Pro/TABLE editor.

Choose Done to find the pattern creation successful.

5. Add two more tables for the pattern.

Choose Modify from the PART menu.

Choose Pattern Table.

Select the existing table (SLOTS_48H) from the TABLES dialog (Figure 6).

Figure 6. TABLES dialog.

Click on the button to add another table.

Enter SLOTS_42H as the name of the pattern table.

Enter the value of the driving dimension for the other members of the pattern (Figure 7).

Figure 7. Pattern table for slots (42” high plate)

Save the Table and Exit out of the Pro/TABLE editor.

Click on the button again to add another table.

Enter SLOTS_36H as the name of the pattern table.

Enter the value of the driving dimension for the other members of the pattern (Figure 8).

Figure 8. Pattern table for slots (36” high plate).

Save the Table and Exit out of the Pro/TABLE editor.

Click OK button, to close the TABLES dialog.

6. Find Feature ID of the pattern leader, to be used in writing the relations that drive the pattern of slots based on the height of the rectangular plate.

In the MODEL TREE, right click on the PATTERN just created.

Choose Info, Feature from the pop-up menu (Figure 9).

Figure 9. Getting info on the Feature from the Model Tree..

Note the INTERNAL FEATURE ID from the information window (Figure 10).
Caution: YOU MAY GET A DIFFERENT FEATURE ID.

Figure 10. Internal Feature ID.

7. Write the Relations.

By now you’ve got everything ready to instruct Pro/ENGINEER to pickup the corresponding pattern table to create the pattern based on height of the plate.

Choose Relations, Edit Rel

Enter the following relations in the Relations editor.

IF HEIGHT==48
pattern_table:FID_XXXX=“SLOTS_48H”
ENDIF

IF HEIGHT==42
pattern_table:FID_XXXX=“SLOTS_42H”
ENDIF

IF HEIGHT==36
pattern_table:FID_XXXX=“SLOTS_36H”
ENDIF

where XXXX is the Internal Feature ID of the pattern found in step 6.

8. Verify to ensure you met the desired objective.

Modify the height dimension of the plate to 36”, 42” or 48”.

Verify whether the corresponding pattern table is set automatically by choosing Modify, Pattern Table.

The moment you change the height of the rectangular plate, you will find that Pro/ENGINEER has picked up the corresponding pattern table via the awesome power of relations you’ve added to the model.

Dwaraka Nadha Reddy is a design engineer (consultant) at Motor Control Centers, GE-IBC in Hyderabad, India. He can be reached by email at dwarakanadha.reddy@ge.com.