Design of backdoor

AUTOMOTIVE DESIGN OF CAR BACK DOOR USING NX CAD

Objective :- 

1. Create a backdoor from the given styling surface using appropriate design methods.

2. The objective of this project is to design a BIW car rear door with inner panel, outer panel and braces for hinges, gas stay, wiper motor and latch as per engineering standards.

3. The inner panel shall be subjected to a draw analysis to verify that it meets the deep drawing requirements for the tool direction established in the design.

Introduction:-

1. A car's tailgate is the rearmost part of the vehicle that allows access to the vehicle's trunk. The tailgate also supports bracing and added weight to the wiper motor, gas hold, tail lamp and latches and striker.
2. The back door/back cover is one of the closing commodities in BIW sheet metal design. The tailgate has many components inside and is designed to be easily incorporated. It affects the rear view and the luggage compartment.
3. The material used to make the door depends on the budget and performance of the vehicle. Aluminum and steel will mostly be used, while low-budget vehicles use steel, which makes the manufacturing process easy and cost-effective as it follows die-pressing.

Major Parts and Reinforcements:-

  The backdoor consists of the following basic components:

1. Backdoor Outer Panel (Upper)

2. Backdoor Outer Panel (Lower)

3. Backdoor Inner Panel

4. Hinge Reinforcements (LH & RH)

5. Gas-Stay Reinforcements (LH & RH)

6. Latch and Striker Reinforcement

7. Wiper motor Reinforcement

Tailgate:-

A tailgate is a door on the back of a truck or car that is hinged at the bottom so it opens downwards.

Design consideration of backdoor:-

1. Functional Requirement of Hinge and gas stay 

2. Rear visibility criteria

3. Luggage volume

4. Crash Analysis

5. Bend Test, Dent Test, Torsion Test & Endurance Test

6. Rear Crash Regulation

7. Gap and flushness Requirements

Design of backdoor outer panel:-

1. The outer panel is a stylish rear door finish. Other tailgate components are designed with the outer panel in mind. It functions as an outer cover and deals with the aesthetics of the car.

In this design, the outer panel is divided into two parts

Outer upper panel

Outer lower panel

Outer Upper Panel:-

1. The Outer Upper Panel Extracted from a styling surface.
2. The panel is altered for the required design with the surface tools of NX CAD
3. The thickness provided for the outer panel is 0.75 mm
4. Hemming is provided with the corner relief.

Outer Lower Panel:-

1. The Outer Upper Panel Extracted from a styling surface.
2. The panel is altered for the required design with the surface tools of NX CAD
3. The thickness provided for the outer panel is 0.75 mm
4. Hemming is provided with the corner relief.

Outer Upper & Lower Panel:-

Tooling Direction:-

1. Before starting the design of the rear door inner panel, a tool direction should be established for deep drawing purposes.
2. After that, the styling surface needs to be checked and analyzed, as it may have irregularities and therefore needs to be corrected first.
3. Then the back door was designed using a top-down approach.

Design of backdoor inner panel:-

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

1. After creating the tooling direction, the design of the inner panel begins, where we first develop an effective sealing flange by checking all boundaries and following the shape of the design of the inner panel. By creating multiple flanges and using surface modeling techniques, a design concept for the inner panel was created.
2. After the interior panel concept is developed, the subordinate components such as hinge, latch, gas-stay placement and reinforcement must be designed. Which completes the overall design of the tailgate.
3. The reliefs have been created in a "V-Shape or Y-Shape" so that if the vehicle goes through a crash, the force is dissipated through it, reducing the damage transferred to the boot.

 

Mastic sealent:-

1. 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.
2. 4 to 5 mm gap for mastic sealent.

Hinge, gas stay & wiper motor emboss :-

1. The blue circle indicates a hinge relief that was created using an auxiliary plane and a relief element in NX. It was also designed in such a way that the embossing should have a flat surface for mounting the hinges using it.
2. The yellow circle indicates the relief of the gas stay, which was created using the surface of the connecting flange.
3. The white circle indicates the wiper motor embossing that was created using the connecting flange.

Latch & striker emboss :-

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.

Striker position:-

The position of the hinge should be perpendicular to the latch when the latch and latch meet. A circle is drawn from the center of the hinge axis to find the striker path and placed perpendicular to the path.

Hemming:-

Hemming and hemming are two similar metalworking processes in which the edge of a sheet is rolled over itself. Hemming is a process where the edge is rolled flat.

1. The outer panel was designed as two separate parts named outer panel upper and outer panel lower.
2. Following the design of the outer panel, the Hemming was created by offsetting the surface using face blending and drawn surface.
3. Two separate outer panels will be joined using Blanking.

Corner relief:-

During the flanging process, the Corner Relief helps to control the behavior of the sheet material and prevent unwanted deformation during bending operations and also helps to reduce the number of flanging passes.

Reinforcements:-

The thickness provided for all reinforcements is 1.5 mm.

1. HINGE REINFORCEMENT

2. GAS STAY REINFORCEMENT

3. WIPER MOTOR REINFORCEMENT

4. LATCH REINFORCEMENT

All reinforcements were created in the same way, first using extraction geometry to create a connected body for each one separately and then crop and then thicken the required part.

Hinge reinforcement:-

1. Hinges allow the rear door to be opened and closed. One end of the hinge is fixed on the rear door and the other end on the roof, on both sides. Hinges can be located outside or inside the rear door.
2. Hinge stiffeners are added to compensate for the weak area due to the load acting on it.

Gas Stay Reinforcement:-

1. Gas Stay is a device used to support the rear door in its open position. The gas anchor requires no manpower and is automatically retracted into the support position when the rear door is opened. One end of the Gas Stay is attached to the tailgate and the other end to the side of the body or the stationary area of ​​the tailgate.
2. Embossing is available in the Gas Stay mounting area to compensate for weakness and improve strength.

Wiper motor reinforcements:-

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

Latch and Striker Reinforcement:-

Latch & Striker form the locking mechanism of the rear door with the car. Due to the regular opening, closing and excessive slamming of the tailgate, stress is placed on the Latch and Striker area. To compensate for this, reinforcements are added in this area.

Draft analysis:-

1. A draft analysis will be performed for the tool direction first created to check if the model is suitable for production.
2. Then, in order to obtain a complete green part, the necessary changes to the draft angle of the reliefs were made using model optimization.
3. The draft Analysis command allows us to see if the drawn part will be easily removed or not.
4. This type of analysis is performed based on color ranges identifying zones on the analyzed element where the deviation from the dip direction at any point corresponds to the specified values.

Views of the designed Back Door:-

Front view-

Back view-

Bottom view:-

Left view:-

Right view:-

Top view:-

Iso view:-

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.