Week 8 - Challenge 2 - Base Bracket Design

BASE BRACKET DESIGN

Objective: To design Base Bracket and perform draft analysis on the model along the tooling axis meeting the requirements of the draft angle.

Introduction:

Class A Surface:

In automotive design, a class A surface is any of a set of freeform surfaces of high efficiency and quality. Although, strictly, it is nothing more than saying the surfaces have curvature and tangency alignment to ideal aesthetical reflection quality, many people interpret class A surfaces to have G2 (or even G3) curvature continuity to one another.

Class A surfacing is done using computer-aided industrial design applications. Class A surface modellers are also called ‘digital sculptures’ in the industry. Industrial designers develop their design styling through the A surface, the physical surface the end user can feel, touch, see etc.

Class B Surface:

Class B Surface is a surface below a certain thickness from a Class A Surface. We can also say that it is an engineering surface because it contains all the engineering aspects of the model which is required.

Class C Surface:

Class C Surface is a surface that joins the Class A Surface with Class B Surface.

Tooling Axis:

Tooling axis is the direction in which the mold or core and cavity opens.

Draft:

Draft is the angle in which the part is tapered to allow it to release. As the part cools, it tends to shrink to the core side of the mold. Draft is required on all parts in the direction of mold movement in order to allow parts to release or eject from the mold properly.

Most parts or applications require a minimum of 0.5 to 1 degree, however 3 degree is widely accepted as normal.

Draft Analysis:

Draft analysis is done in order to detect if the part that has been drafted will be easily removed or not. This type of analysis is performed based on the colour ranges identifying zones on the analyzed elements where the deviation from the draft direction at any point corresponds to the specified values. When the draft analysis passes, it means our part is easily toolable or can be easily ejected.

Methodology/Approach:

Procedure:

1. Importing Class A Surface

First of all we have to import the class A Surface into the Catia V5 Software.

2. Continuity Check

After getting the Class A Surface from the styling team, we have to ensure that the Class a Surface is properly joined and has no discontinuity on it. To check that we have to use the Boundary command or Join command.

3. Creation of Tooling Axis

First of all we have to analyse manually or visually to see which direction is the most appropriate for tooling axis. After analysing we found that in x directing the holes are creating problems, y direction is we cannot do because no holes are visible and also ribs are difficult to be tooled and z direction we found it very easy to be tooled. So, we create a dummy tooling axis along z direction and the we create a final tooling axis using bisecting line method.

Bisecting line Method:

As we have created a dummy tooling axis, we will use x direction and y direction to see if they are clearing a tooling or not. In x direction we do not found any problem as it does not have any parallel faces. So, we will intersect YZ plane of the axis system with class A Surface. Then create lines using point to point option and then create a final line using bisecting line option using the previous lines created. This line is our final tooling axis.

4. Draft Analysis of Class A Surface

First of all we should change the view to the Customize View parameters and then select the material mode and the ok. After that we will open draft analysis command and then click on the compass icon and then align the compass of the window with the tooling axis earlier created and then lock the draft direction. After that click on the surface and see that the surface is within permissible limit of the draft value. The surface should be green and in the column 3 degree should be inserted.

5. Creation of Class B Surface:

First of all we will divide the flat surface, the ribs and the angled surface and then perform the action one by one.

For Ribs;

• Extract the flat surface and not the filleted surface

• Untrim them

• Extrapolate them

• Trim them

• Offset the surface by 2.5 mm downward

Same For the Rib 2;

For Base Surface;

• Extract the slanted surface

• Untrim them

• Extrapolate them

• Offset the surface

• Do the same for flat surface and then trim with the base surface and ribs

• Fillet the surfaces by adding the offset distance

• This is our final B surface

6. Creation of Class C Surface:

For class C Surface we have to extract outer the boundary and the holes boundary of the class a Surface and sweep them one by one downward using the tooling axis with the draft direction and the join them to get one class C Surface.

7. Solid Body Formation

Join the class C surface with class A surface.

Trim the B surface with the join created earlier.

Go to the part workbench and close the part using close surface option.

8. Final Draft Analysis:

First of all, change the view to Customize View Parameters and then check material mode selected and perform draft analysis as done earlier for Class A Surface.

3D View:

Isometric View:

Front View:

Side View:

Top View:

Tree Structure:

Conclusion:

From the given Class A Surface, Class B Surface and Class C Surface were created to form a solid model and Draft analysis was done for both Class A Surface and the 3d model along with the tooling axis meeting the requirement of draft angle.