Week 8 - Challenge 3 - Switch Bezel Design

Aim/ Objective:

Create the Switch Bezel 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.

Taking the Thickness of the component to be 2.5 mm.

Detailed Report:

Terms used:

Class A surface: It is outermost surface of automobile which gives aesthetic look to vehicle. It is physically touchable. It is obtained from clay modeling by reverse engineering. This surface is given input to plastic product designer to work.

Class B surface: This surface is created by taking offset from class A surface. It is surface on which all engineering feature like screw bosses, dog house, ribs & mounting are created.

Class ‘C’ surface: This is surface which joins class A & class B together.

Tooling axis: It is the direction in which core & cavity opens & closes.

Method followed:

1. Checking continuity of class A surface.
2. Deciding feasible tooling direction & creating tooling axis.
3. Performing draft analysis on class A surface.
4. Creating class B surface from given class A surface.
5. Creating class C surface to join A & B class surface.
6. Creating solid feature by using closed surface.
7. Performing draft analysis on final plastic component.

1. Checking continuity of given class A surface:

First of all we have to check continuity of given class A surface to ensure class A surface is properly joined or no discontinuity present. This can be done by using join or boundary command in CATIA . By looking visually in below image we see that surface has continuous connected boundary as highlighted by green line.

• Extracting the boundary of given class A surface we also check that continuity visually. Below figure shows base bracket model has continuity in class A surface.

2. Creating tooling axis direction:

Next step is to decide tooling axis direction. Consider Z axis as tooling direction & analyzing the model to see which faces will create problem for tooling.  Top resting surface i.e. pink color surface & bottom green color surface will not create problem for tooling because they are approximate perpendicular to tooling axis. From the below image the vertical faces of pocket (in blue color) will create problem during tooling so making tooling axis to their respective direction.

• Now we will use bisecting method to find real tooling axis. In order to create tooling axis in Z- direction, extract the bottom green surface of class A surface. Take point on that surface. Insert axis system at this point.

• In order to find real tooling axis in Z direction, create positioned sketch on YZ plane of axis system. Take intersection of class A surface we get the curve as shown in below. Draw two lines along the to two side faces of the pocket. Create bisecting line to these two lines. This is our first line to create real tooling axis.

• Similarly, Create positioned sketch on XZ plane of the axis system. Take intersection of class A surface in that sketch. But here we get only one line as there is one face. So draw a line at an angle of 3° initially later it will be changed to approximate 6°.

• Now we get two lines. We will get our tooling axis by creating bisecting line to these two lines.

3. Performing draft analysis on class A surface:

1. To perform draft analysis. Go to insert < Analysis< Feature draft analysis.
2. Switch customize view parameter mode to material.
3. Click on compass icon & align it with the tooling axis & click on the surface, we will get our results.
4. From the below image it is seen that surface in green color has more than 3° draft which is most required for tooling feasibility. Also see color variant display box.

4. Creating class B surface from given class A surface.

Dividing class A surface into three surface namely as shown below.

1. Bezel resting surface.
2. Pocket walls.
3. Base surface

We have to work on each surface separately to obtain B class surface. Follow the same procedure for all surfaces.

• Extract the flat surface.
• Un-trim the surface.
• Extrapolate it.
• Offset it by 2.5 mm distance

As per above we get following three surface

• Bezel resting surface.

• Pocket walls.

• Base surface

• Finally trimming of offsetted surface together, we get B class surface as shown below.

• This trim B class surface is our inner surface so fillet edges of this surface as per below formula. It is necessary to achieve uniform wall thickness.

Fillet radius = Class A surface fillet value - Part thickness.

5. Creating class C surface to join A & B class surface.

• Extract the boundary of the class A surface two separate curves by using multiple extract tool. Smoothen these two curves to remove small patches of the surface.

• Sweeping the boundary of class A surface with the use of draft direction as tooling axis.

• We observe gap between these two swept surfaces.

  

• So extrapolating & trimming with each other we get class C surface.

• Make joining between the class A & C surface with merging distance 0.003. But we are not allowed to increase the merging distance more than 0.03. So this join will not form complete close loop boundary as there are small gap observe.

• This issue is fixed by creating join with sub elements and separates the top portion using sub elements to remove. After that extrapolate the separated top surface then again trim them both.

• Final closed surface is obtained by trimming earlier surface with B class surface.

6. Creating solid feature by using closed surface.

Solid model is created from closed surface in the part workbench.

7. Performing draft analysis on final plastic component.

Performing the draft analysis again with the same procedure as mentioned above.

• Below image shows running point draft analysis.

• Below image shows full draft analysis.

• Images of the solid model with the proper color code of the draft angle in various orientations (Isometric, Front, Side, and Top View).

ISO view:

Front view:

Left side view:

Right side view:

Top view:

• Image of the expanded tree structure for the geometrical sets & part body.

• Image of the publications of tooling axis & class A, B & C surface