Design of backdoor

Design of backdoor of a car

OBJECTIVE:

1. Develop a back door using appropriate design methodologies and explain about the components developed in the design.
2. Design a BIW Back Door of a car with an Inner Panel, Outer Panel, and Reinforcements for the Hinges, Gas stay, Wiper Motor, and Latch by following the engineering standards.
3. The Inner Panel must be subjected to Draft Analysis for verifying whether it satisfies the Deep Drawing requirements for the tooling direction created in the design.

What is backdoor of a car ?

The backdoor of a car, also known as the rear door or tailgate, is a hinged door at the rear of a vehicle that provides access to the cargo area or trunk. It can be opened and closed manually or electronically, depending on the make and model of the car. The backdoor is an important part of the car's design as it allows for easy loading and unloading of cargo. It is the rearmost 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.

What are major parts and reinforcements ?

The backdoor consists of the following basic components:

• Backdoor Outer Panel (Upper)
• Backdoor Outer Panel (Lower)
• Backdoor Inner Panel
• Hinge Reinforcements (LH & RH)
• Gas-Stay Reinforcements (LH & RH)
• Latch and Striker Reinforcement
• Wiper motor Reinforcement

What is the design intention, design consideration and design methodology ?

The intention of this 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:

• Functional Requirement of Hinge and gas stay
• Rear visibility criteria
• Luggage volume
• Crash Analysis
• Bend Test, Dent Test, Torsion Test & Endurance Test
• Rear Crash Regulation
• Gap and flushness Requirements

DESIGN METHODOLOGY:

1. Conversion and extraction of required surface from the given styling surface.
2. Modelling the reinforcement parts such as outer panel upper, outer panel lower, gas stay, latch & striker, wiper motor reinforcement.
3. Creating embosses and other parameters such as creating emboss for windshield, wiper, hinge and gas stay.
4. Creating tooling direction.
5. Creating sealing flance
6. Creating emboss for windshield, wiper, hinge and gas stay.
7. Creating trajectory for latch and striker.
8. Creating flange for mastic sealant.
9. Draft analysis.

DESIGN OF OUTER PANEL:

The Outer Panel is the styling surface of the back door. Other components of the backdoor are designed with reference to the outer panel. It acts as the outer cover and deals with the aesthetics of the car.

In this design outer panel is divided into two parts

1. Outer Panel upper
2. Outer Panel lower

Outer panel upper

The Outer Upper Panel Extracted from a styling surface. The panel is altered for the required design with the surface tools of NX CAD. The thickness provided for the outer panel is 0.75 mm

Outer panel lower

The Outer Upper Panel Extracted from a styling surface. The panel is altered for the required design with the surface tools of NX CAD. The thickness provided for the outer panel is 0.75 mm.

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.

Position of latch

Position of latch and striker is perpendicular to the hinge then only the latch and striker mechanism works properly when the door opening and closing position.

Design of backdoor inner panel:

Inner door panel is a component which is use for strengthening the door assembly and it is one of the most important components on witch all accessories are mount like hinges, glass guide channel and gas stay.Back door inner panel is mounted with the the Roof.

• The Inner Panel is extracted from the styling surface.
• Materials used for the Inner panels are steels, Aluminum.

• 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.
• 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.

• The hinge, gas stay, latch, wiper motor emboss was created by using the datum plane/surface of the connecting flange and emboss feature in NX.

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

Design of reinforcements:

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

The thickness given to all reinforcements is 1.5 mm. 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.

Hinge reinforcements

Hinges enable the opening and closing of the back door. One end of the hinge is fixed on the backdoor and the other end on the Roof, on both sides. Hinges can be placed outside or inside the backdoor. The hinge reinforcements are added to compensate for the weak region due to the acting load over it.

Gas stay reinforcements

Gas Stay is a device used for supporting the back door in its open position. Gas stay requires no manpower and is engaged into support position automatically as the back door opens. One end of the Gas Stay is fixed on the backdoor and the other end on the Body Side or on the Back door stationary area.

Wiper motor reinforcement

Wiper motor reinforcement is created to mount the wiper motor assembly.

Latch reinforcement

The Latch & Striker forms the locking mechanism of the backdoor with the car. Due to regular opening, closing, and over slamming of the backdoor, there is stress developed in the Latch and Striker area. To compensate for the same, reinforcements are added in this area.

Draft Analysis

The draft analysis will be performed for the tooling direction created at first and checked that the model is suitable for manufacturing. 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.

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.