CATIA-Week 8.4- Bumper

AIM-

Create the Bumper Plastic component using the provided Class-A surface. Create a tooling axis for the given Class-A Surface with all the requirements of draft angle and at the end perform the Draft analysis on the model.

OBJECTIVE-

• Design Bumper as per automotive industry Standard.
• Perform Draft analysis and Create Tooling Axis on Class-A surface.
• Create B Class and C Class surface.
• Create final surface model and convert it into solid body
• Perform draft analysis on Final part body.

INTRODUCTION-

A bumper is a structure attached to or integrated with the front and rear ends of a motor vehicle, to absorb impact in a minor collision, ideally minimizing repair costs.

They are designed to absorb impact to the front and rear of vehicles and minimize low-speed collision damage. Today, standard passenger vehicle bumpers have a rigid reinforcing bar under the outer cover, with sections of compressible foam or plastic underneath.

A bumper is made up of four parts:

• Bumper cover.
• The bumper absorber.
• The bumper reinforcement bar.
• The bumper mounting system.

DESIGN METHODOLOGY

Tooling Direction for Plastic Part : Tooling direction is main consideration for plastic part and mold parts because it defines movement of mold part and possibility of plastic part to come-out from mold part (Core and Cavity).

• In Molding machine arrangement is given to open the mold along a direction which is known as Tooling Direction.
• In other words. The mold is built from two separate halves (Core and Cavity) and tooling direction basically define the direction of mold pulls apart.
• Tooling direction is known as primary direction.

Method opted for creating tooling axis for the bumper

• Check the best tooling direction for the given surface.
• We can find out the best tooling direction by cross checking all the three axes.

• Here we can find out that the best tooling direction for the pumper class-A surface is along x-axis direction
• The method I choose to create the tooling axis is first extracted a surface and create a midpoint on that surface. The introduced an axis system on that point.
• Then created a with the point and direction along x axis.
• Here both the outer flanges have 5.1-degree draft with respect to the axis created. Hence going with the axis created will not make any difficulties during the draft analysis.

Draft analysis for the given CLASS-A surface

The Draft Analysis is a 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 draft 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.

CLASS-B SURFACE CREATION-

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.

• Offset the class-A surface to 3mm inward direction.
• Rework on the patches and discontinuity of the offset surfaces using the features like extract, multi-extract, sweep, multi-section surfaces, extrapolate.
• To ensure the continuity of the Class-B surfaces check the boundary command to find out the boundary.
• Hence class-B surface creation is done.

CLASS-C SURFACE CREATION-

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

Since it is a complex class-A surface, we cannot simply create the class-A boundary curve and sweep it at one shot. Hence, we need to create smaller curves using multi-extract command and then create sweep of 90 degree with reference to the surface option. sweeps at the midportion of the bumper should have a 93 degree vaue to pass the draft analysis.

Creating the final surface of Bumper

• First step is to join the CLASS-A surface with CLASS-C surface.
• Then Trim the Joined surface with CLASS-B surface to achieve the final Bumper surface.

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 (Front, Top, Side and Isometric View)

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.

The expanded Tree Structure for the Geometrical Set and the Part Body

CONCLUSION-

Successfully created the Tooling Direction, analyze Class-A surface using Draft Analysis and constructed Class-B and Class-C surfaces of Bumper using the given Class-A surface also perform Draft analysis on Final plastic part in the CATIA surface workbench.