ME-546 Computer Aided Manufacturing

Lesson 6 -- Rivet

 

Pro/ENGINEER Functions

Relations

 

Design Objective

This lesson asks you to create a fairly simple part without any assistance. Once you have completed that, you will use the Relations function to define arithmetic relationships among dimensions.

 

Modeling Strategy

I. Create the part as shown in Figure II.6-1.

II. Use the Relations function to add dimensional relations to the part.

III. Experiment with different dimension values to see how Relations affect the part.

 

Detailed Construction

I.On your own, create the part portrayed in Figure II.6-1. Creat the rivet head with a revolve and the shaft with a separate protrusion feature. The length of the shaft is 4 inches. To view a cross section of the part, refer to Figure II.6-2.

II. Use the Relations function to add dimensional relations to the part.
Relations are equations written between symbolic dimensions and parameters. By writing relations between dimensions in a part or an assembly, the effect of modifications can be controlled. For example, the length of one side of a part could be expressed as two times whatever value the width of that part is.

There are two types of dimensions in Pro/ENGINEER:

• comparison dimensions, such as: IF (dimension1 + 2.5) > = dimension2...
• equality dimensions, such as: dimension=dimension 2*SQRT(dimension3+7.)

For a complete listing of all parameter symbols used in relations, refer to the Pro/ENGINEER Modeling User's Guide.

Define a relation to constrain the diameter of the hole to be 3/4 of the face width:

1. PART - Relations - Part Rel
1. - Select the rivet.
2. - Add
3. - Enter a formula, using the dimension names displayed, to make the radius of the head two times the base radius, and the length four times the base radius.
   Note: For this example, d0 is the basic radius, d1 is the length , and d2 is the head radius. These values may vary, depending on the order in which you created your dimensions. Your symbols might be different!

                        d1 = 4 * d0
                        d2 = 2* d0

4. Press RETURN.
5. - Switch Dims
   

Doing this switches the dimesions back to the parameter values.

2. Done
3. PART - Modify
   Select and dimension the base radius and change it to 2.
   - Regenerate
   Notice what happens when you regenerate the sketch.
   
4. Modify an existing relation:
1. PART - Relations - Part Rel
   Select the rivet.
   - Edit Rel
   A text editor window appears.
   Use the editor to edit the relations.

                        d1 = 10 * d0

Save and close the notepad file

2. Done
3. PART - Regenerate

Choose a relation for the shaft parameters such that the exposed surface area of the hemispheric rivet head equals 1 unit area and is the same as that of the exposed shaft surfaces and the area of the end of the shaft is the same as the that of the cylindrical surface.