DESIGNING A BIW BACK DOOR OF A CAR

OBJECTIVE

The objective of this project is to design a BIW Back Door of a car with Inner Panel, Outer Panel and the Reinforcements for the Hinges, Gas stay, Wiper Motor and Latch by following the engineering standards. The Inner Panel must be subjected to Draft Analysis for verifying whether it satisfies the Deep Drawing requirements for the tooling direction created.

INTRODUCTION

The Back Door of a car is the rear most part of the vehicle which gives access to the trunk space of the vehicle. The rear door also supports the reinforcements and added weights of the Wiper Motor, Gas Stay, Tail Lamp and Latch and Striker. The back door is usually made of an inner panel and 2 or 3 separate inner panels joined together by hemming or spot welding wherever necessary. The material used for the door manufacturing depends on the budget and performance of the vehicle. Mostly Aluminium and Steel will be used whereas low budget vehicle use Steel which makes the manufacturing process easy and cost efficient since it follows the Stamping of Moulds. But Aluminium were used for high budget cars since it increases the manufacturing cost since the Aluminium parts will be mostly die casted hence it has variable thickness which reduces the requirement of reinforcements but improves the performance of the car rapidly since Aluminium is not heavy as steel.

DESIGN INTENT

The intent of the project is to design a Body In White Back Door of the vehicle considering the engineering standards and manufacturing requirements which satisfies the Deep Drawing process.

DESIGN CONSIDERATION

• Rear visibility criteria
• Luggage volume
• Crash Analysis
• Bend Test
• Dent Test
• Torsion Test
• Endurance Test
• Abuse Case
• Assembly Load Case

DESIGN METHODOLOGY

TOOLING DIRECTION

• Before starting to design the inner panel of the back door the tooling direction for Deep Drawing purpose should be created.
• Then the styling surface needs to be checked and analyzed since it might have irregularities, hence it must be fixed first.
• Then the back door was designed using the top down approach.

BACK DOOR INNER PANEL

• After creating the tooling direction the design of the inner panel will begin where we will first develop an effective sealing flange by checking all the boundaries and by following the shape of the inner panel design.
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• By creating multiple flanges and by using surface modeling techniques the concept design of the inner panel was created.
• After the concept of the inner panel is developed, then the child components like a hinge, latch, gas-stay locations and their reinforcements must be designed. Which complete the overall design of the tailgate.
• The embosses were created in ‘V-Shape or Y-Shape’ so that if the vehicle undergoes the crash then the force dissipates over it which reduces the damage transferred to the trunk space.
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MASTIC SEALANT

• The mastic sealant is used to fix the inner panel with the outer panel which increases the NVH factor and stiffness of the back door.

HINGE AND GAS STAY EMBOSS

• The red circle denotes the hinge emboss which was created using the datum plane and emboss feature in NX. It was also designed in a way that the emboss should have a flat surface for assembling the hinges using it.
• The orange circle denotes the gas stay emboss which was created using the surface of the connecting flange.

LATCH AND STRIKER EMBOSS

• The Latch and Striker emboss were designed by creating a trajectory which follows the opening and closing of the back door with respect to the hinge axis.
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DRAFT ANALYSIS

• The draft analysis will be performed for the tooling direction created at first and checked that the model is suitable for manufacturing.
• Then to get a complete green portion the necessary changes to the draft angle of the embosses were carried out by optimizing the model.
• The Draft Analysis command enables us to detect that the part drafted will be easily removed or not.
• This type of analysis is performed based on color ranges identifying zones on the analyzed element where the deviation from the draft direction at any point, corresponds to specified values.

DESIGNING THE REINFORCEMENTS

1. HINGE REINFORCEMENT
2. GAS STAY REINFORCEMENT
3. WIPER MOTOR REINFORCEMENT
4. LATCH REINFORCEMENT

All the reinforcements were created using the same method, first the linked body was created separately for each with the help of extract geometry and then the required portion was trimmed out and then thickened it.

BACK DOOR OUTER PANEL

• The Back Door outer panel was created using the styling surface.
• The outer panel was designed as two separate parts named as outer panel upper and outer panel lower.
• After designing the outer panel the Hemming was created by offsetting the surface with the help of face blend and swept surface.
• The two separate outer panel will be joined using Blanking.

HEMMING

Hemming and seaming are two similar metalworking processes in which a sheet metal edge is rolled over onto itself. Hemming is the process in which the edge is rolled flush to itself.

CORNER RELIEF

Relief helps to control sheet metal material behavior and to prevent unwanted deformation during unbend operations and also helps to reduce the number of passes in hemming.

CONCLUSION

Thus the Body In White Back Door of a car was designed following the engineering standards and also the deep drawing requirements were satisfied.