Week 8 - Challenge 3 - Coin Holder Design

COIN HOLDER DESIGN - CHALLENGE 3

AIM

Create the Coin Holder 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.

1. INTRODUCTION

Coin holder is a part which acts as a pocket for carrying coins and other small things like pen drives, keys etc. Mostly is places in a very easily accessible point where a driver can grab things in the con holder without any difficulties.

CLASS-A Surface

Class-A surface means visible surface. It gives the aesthetic of the component which is created by the styling team and gives to the part design engineer to create the part with all engineering aspects.

CLASS-B Surface

Class-B surface means thickness of a part it is not visible and is inside part. In other words, Class-B surface is a surface below a certain thickness from the class-A surface. This is the surface that contains engineering aspects of a model.

CLASS-C Surface

Surface that joins class-A and class-B surfaces is class-C surface. Class C is often specified for interior surfaces not readily visible, surfaces that will be covered by another part when assembled

2. OBJECTIVE

• To design coin holder as per automotive industry Standard.
• Create tooling axis for the given CLASS-A surface.
• Create B Class and C Class
• Create final surface model and covert it into solid body using close surface command in the part design workbench
• Perform draft analysis for both Class-A surface and Final part body.

3. DESIGN METHODOLOGY

Skin data would be provided by the styling team to the part designer

The first step is to check the continuity of the class A surface. This is to ensure that there is no gap between surfaces. If we find any then we should fix that first.

3.1 Class-A continuity check

• Analyse the class A surface through visual inspection.
• To make sure that the given surface has no gap in between them, We can check it also with the help of Join or boundary commands.
• Continuity error has been detected on the top left corner in between the top wall and the side flange area.

Reworking on the error surface

• STEP 1- Join the CLASS-A surface without the error face and its adjacent faces.

• STEP 2- Hide the error face and create the boundary curves with the help of adjacent surfaces. Then using sweep command create new face with tangent continuity along the support faces.

• STEP 3- Join the sweep surface and adjacent surfaces with the first joined surface and check the continuity and boundary of the joined surface.

Here the reworked surface has only one boundary which means the surface has no patches or irregularities and it is good to go for further design procedures.

3.2 Procedure for creating the tooling axis

Tooling axis represents the opening and closing of the mold core and cavity during the manufacturing of the components. A plastic product designer should consider the best tooling direction to cutdown the cost of the component very less.

Method opted for creating tooling axis for the Coin Holder

• Check the best tooling direction for the given surface.
• We can find out the best tooling direction by cross checking all the three axes.
• Since it has a bin with walls, extract the base surface and create a midpoint on it.

• Create a new axis system with respect to the point created.
• Here by checking it is clear that the best possible tooling direction is along z axis.
• Using intersect command, make intersects along x and y direction.
• Check the draft angle for the wall faces. It is clear that all the walls created with a draft angle of 3.02 degrees. Hence, we can create a line on the point and along z direction for creating the Tooling axis.

• Other method for creating tooling axis is by using the intersection, create two lines on the walls and then create a bisecting line with the two lines on the point.

3.3 Draft analysis for the given CLASS-A surface

The Draft Analysis command enables you to detect if the part you drafted will be easily removed. This type of analysis is performed based on colour ranges identifying zones on the analysed element where the deviation from the draft direction at any point, corresponds to specified values.

Draft analysis is done after determining the tooling axis, draft analysis is used to check whether the minimum draft (3 degrees) is maintained or not.

Procedure for performing the draft analysis are as follows

• Change the view mode of the component to be in customized parameter mode and then select the shading mode as materials.

• Then open the featured draft analysis tool from the insert menu.

• Then click on use the compass to define the current drafting direction and then drag and align the compass on the Tooling axis.

• Then lock the draft direction and perform draft analysis by clicking on the component.
• The green colour shows the positive daft tooling direction and the given surface passes the draft analysis.

• Click on the analyses under the running point to check the draft analysis on the individual faces. It shows how much draft on specific points when we move the cursor point.

3.4 SURFACE-B CREATION

• First step is to extract the base surfaces
• Untrim the extracted surfaces
• Extrapolate the untrimmed surfaces
• Trim the extrapolated surfaces and then offset it with 2.5mm distance along the desired direction

• Extract the side walls and the follow the same procedure done for the base surfaces and offset it 2.5mm outwards

• Offset the side walls and Trim it with the base surface

• Then multi-extract the top side walls and extrapolate it. Trim the extrapolated top wall with the side wall surface.

• Extract the side flanges, extrapolate it, offset it and the trim with the above surface created

Last procedure is to provide desired fillets to the edges on the surfaces in such a way that the final surface should have a uniform thickness. And CLASS-B surface is created.

3.5 SURFACE-C Creation

The method for creating the class-C surface is

• First create the boundary curve of CLASS-A surface using the Boundary command Or Extract command.

• Then multi extract the adjacent surfaces for supporting the sweep surface to be created.

• Using the Sweep command with reference surface option, sweep the curve at an angle 90 degree towards the class-B surface.

• The sweep surface created is the CLASS-C surface.

3.6 Creating the Final surface for the coin holder

• Join the CLASS-A surface with the CLASS-C surface.

• Trim the joined surface with the CLASS-B surface to get the final surface

3.7 Go to the part design work bench and using the close surface command create the base bracket solid part body

3D Part model in various orientations (Isometric, Front, Side, and Top View)

The expanded Tree Structure for the geometrical set and the Part Body

4. DRAFT ANALYSIS of the Final part body

Same procedure for the draft analysis of CLASS-A surface is followed.

• Change the view mode to material shading
• Align the Compass with Tooling axis.
• Lock the draft direction and perform the Draft analysis.

Conclusion

I have successfully created the class-B and Class-C surfaces of COIN HOLDER using the given Class-A surface along with the tooling axis in the CATIA surface workbench. And also created the final part body using the close surface command in the part design workbench and performed draft analysis for the same.