Spring - Make Flexible in Pro/ENGINEER Assembly

Elastic items always fit into the assigned space in an assembly. It may change its length, width, major & minor diameter or/and so on. Common elastic items in engineering are spring (compression, tension, torsion), rubber and foam.

In any MCAD, we used to draw a few of the elastic model with different dimensions. For example, spring can fit into an assembly with varies of length. So spring model like spring_10mm, spring_12mm, spring_15mm are created and inserted into assembly. There is nothing wrong except the Bill of Materials (BOM) or part list. Instead of displaying Spring in 3 units, the BOM shows spring_10mm, spring_12mm, spring_15mm in 1 unit each. This has created an inaccurate BOM.

In Pro/ENGINEER, we use the flexible component to overcome this problem. Flexible component will allow us to make its dimension varies when it is fit into assembly. In this tutorial, we are using a compression spring as the sample.

Download: CAD models for tutorial

* Before started, open the spring.prt and resume the protrusion feature.

1. Open the assembly make_flexible.asm

 

2. Note that the springs are now overlapping with the upper block. To activate the make flexible command, select any one of the spring, press and hold right mouse button (RMB) and pick Make flexible from the drop down menu.

3. Varied Items dialog box appears. Here, we will need to pick the dimension which we want to make it varies.

4. Click the ‘plus’ button in the dialog box. After that, pick the spring again. Menu manager appears to specify the desired dimension. Click Profile and Done.

5. The spring length will now display on the screen. Select the spring length and click OK in the small dialog box.

6. The selected dimension will now added into the Varied Items dialog box. Look at the ‘Method’ column, this length is driven by a constant value.

7. Next, click the ‘By Value’ item. A drop down options allow us to choose the method how the dimension to be driven. ‘Distance’ is selected for this tutorial.

 

8. The measure dialog box appears. We are requested to input the reference of the distance measurement.

 

9. Pick the edges / surfaces which the spring should fit in.

The distance from the measurement will now display in the Measure dialog box. Next, click the Close button to close the dialog box.

 

10. Spring length is now assigned with a new value after the distance measurement.

 

11. The image below shows that the selected spring is been compressed.

12. Repeat step 2 to step 10 to make flexible the rest of the springs.

If the upper block is been edited, the spring will be updated.

13. Click Info > Bill of Materials. The BOM shows that there are 3 units of Spring. This is how it should be in the actual scenario.

 

14. (optional) To make the spring return as a normal component, select the spring in the display or model tree, press and hold RMB and choose Remove Var Items. After that, click the Ok button in the confirmation dialog box.




** If you are using your own spring model in tutorial, please remember to write the relation for the pitch value. You can refer to the tutorial below for reference

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