Week 8 - Challenge 4 - Bumper

Bumper Design Using CATIA V5

AIM :

Create the Bumper Plastic component through the given Class-A surface. To begin with, the tooling axis for the given Class-A Surface should be created meeting the requirements of the draft angle and at the end perform the Draft analysis on the model.

Overview :

Initially, we need to offset the given Bumper class A surface in the inner direction to the required thickness (here the thickness is 3mm). After that, we need to close the patches on the offset surface of the bumper, the patches are formed due to the fillets on the Class A surface. Once all the patches are closed properly join them together to make a proper class B surface and now sweep the boundary of the class A surface to trim with the class B surface to make a closed body. By using the closed body command in the Prat workbench we can get the solid body from the closed surface of the Bumper. Now, again went back to the surface workbench to perform the 'Draft analysis' for the solid body.

Specifications :

Bumper Thickness = 3 mm

Minimum Draft Angle = 3 Degrees

Definitions :

1. Class-A Surface: it is a surface created by the styling team which is then given as an input to the plastic designer to create the plastic component. It is the aesthetic surface and the outer most surface.
2. Class-B Surface: it is the surface below a certain thickness from the Class-A surface created by the plastic designer. This surface contains all the engineering aspects of a model.
3. Class-C Surface: it is the surface which joins the Class-A and Class-B surfaces together.
4. Draft: it is the amount of taper or slope given to cores or other parts of the die cavity to permit easy ejection of the casting from the die casting die.

Design Methodology :

Given Class A Surface :

1. Tooling Axis : for creation of the tooling axis, we follow the normal to surface line method.

1. First, ensure that the Class-A surface is properly joined and has no discontinuity. Select the boundary command from the toolbars and then select the Class-A surface. A boundary should only appear on the outer edges of the component.
2. Then, we decide the proper tooling axis direction with respect to the given component (in this case it is the Z-axis direction).
3. Generally, the tooling axis is created using bisecting lines method. But in this model, we observe that the side walls are not given any draft. Hence, we assume the axis normal to the base surface and parallel to side walls.
4. We create a line normal to base surface by creating a point first on that surface and then create the line using the Normal to Surface method and taking the base surface and the point as references. This new line is considered as the tooling axis.

2. Draft Analysis: to check whether our tooling axis is proper or not we do the draft analysis.

1. Go to insert > analysis > feature draft analysis.
2. Align the compass with the tooling axis.
3. Then, click on the Class-A surface to see if the it is within the permissible limit of the draft values.
4. The Class-A surface should turn green and then draft value should be given as 3 degrees.

3. Class-B: we create the Class-B surface by extruding the Class-A surface by 3 mm

1. First, we will use the Extract the total Class A surface by Offsetting it to a distance of 3 degrees.
2. After that, we see that some surfaces could not be extracted properly, thus leaving some small patches which we need to fix by using some surface creation tools like Multi-Sections Surface, Blends and Sweep.
3. After, closing all the small patches we use the Join command to ensure that the surface is properly joined.

4. Class-C: we create the Class-C surface by extruding the edge boundaries of the Class-A surface by 3 mm.

1. First, we extract the outer boundary of the Class-A surface separately.
2. Then, we sweep this boundary using the sweep command. We select the Line option on the sweep command menu, the extracted boundaries as Guide curve 1 and the Class b surface as the Guide Surface. Also, we specify the draft angle as 90 degrees. We give this value because the Class C surface is perpendicular to the Tooling Axis direction.
3. After that, we join all the Class-C surface with the Class-B surface by using the Trim command.
4. Lastly, we use the Join command to join the Class A, B and C surfaces together and obtain the proper desired surface.
5. Also, since the Class A we received was only the half surface of the bumper we Mirror the surface by using the symmetry command and create the full Bumper Surface.

   

5. Surface Body (A+B+C) : we create the final solid body using the Closed Surface command.

1. Go to Boundary command and click on the new surface. An error dialog-box should pop-up.
2. Go to the Part Design workbench.
3. Select the Closed Boundary option and then click on the generated surface.
4. A closed solid body is obtained.

Draft Analysis of Close Surface Body (A+B+C) :

Tree Structure :

Publications :

All Views of Bumper :

Conclusion :

• The Bumper Plastic component through the given Class-A surface is created.
• The tooling axis for the given Class-A Surface should be created.
• The draft angle and at the end perform the Draft analysis on the model are done.