Design of backdoor

CAR BACK DOOR DESIGN by SAHIL PARAB

Aim: To design back door of car using given outer class 'A' surface using SiemensNX.

What is back door of a car?

A door which is located at the rear side of a car which gives access for the boot space to store luggage, spare wheel etc.

These doors can be operated manually or electric powered. In most of the luxury cars door is electrically operated.

It is a hinged board or door at the rear of the vehicle that can be moved up or down during loading and unloading.

Back Door is also referred as 'Hatch' or 'Tailgate' or 'Trunk-lid' or 'Boot-door'. Its the rearmost part of the vehicle which gives access to the trunk and has mounts for tail lamps, hinges, wiper motor, gas stay etc

Types of Backdoor

• Top mounted
• 
• Side mounted
• 
• Lower Mounted.
• 

 Designing of Back Door.

Components to be designed:

1) Outer panel

A door shell is an entire door. The outer panel is just the "face" of the door, the Part you see from outside.

We were given this Lower and Upper Outer face with some errors to fix. After fixing the surface , we worked on it tomake the surface suitable enough forus to make the vigorous edits.

We have done Hemming on the outter surface at places where it hemms the inner panel.

3 face blends was done for Hemming.We see the required surface to be hemmed and do the same accordingly.

Corner Reliefs were given at places where required. 

Why do we give Corner or bend reliefs?

A bend relief is nothing more than two small incisions cut into a piece of sheet metal to free the metal between the two. It separates the material you want to be able to fold from the rest of the part. You only need it when there is material on either side of a bend.

Inner Panel.

The inner panel is one of the most important components of backdoor assembly. It provides strength and helps in dissipation of forces outside the part with the help of embosses made on it. It helps in mounting of accessories like hinges, wiper motor, gas stay, latch & striker etc.

The inner panel is produced by either casting or through Deep drawing process.

Mostly aluminum part is casted, steel inner panel are manufactured by deep drawing process. If deep drawn, there must be a tooling direction through which that panel must be deep drawn.

The Only line here is Tooling Axis.

Sealing Flange: It is that section of the inner panel which enables the backdoor to sit over the rear body side of the car. Its design is important as it decides how a backdoor is mounted on the rear body side of the car and also restricts any external matter to enter inside the vehicle.

I have done here a stepped flange for sealing as a different approach. Kindly note.

Speaking ofwhat we have done here. We have given 

Embosses: It is provided to give extra strength to sheet metal panel and to help dissipate forces/energy towards a specific direction. Here embosses (Y/V emboss) are designed in such a way so as to direct them towards the outer end of the backdoor as shown in the image.

Flange for Mastic sealant. 

5mm gap was left for the inner panel and back door outter panel attachments.

Reinforcements

Reinforcements are generally placed to increase the strength of the panel in localized areas which is relatively small compared to sheet metal parts for absorbing loads imposed there on and dissipating such loads throughout the panel assembly to help maintain rigidity of the panel assembly. The reinforcements are usually 1-1.5mm thick as opposed to 0.75mm thick panel used in this part.

• Hinge reinforcements

Hinge is a pivot mechanism which supports the total weight of the backdoor. So reinforcements are added for strength and rigidity.

• • Gas stay reinforcements

  Gas stay is used to lift the backdoor automatically and is used to support the backdoor in its open position. It can be of Two types Semi-automated and fully automated.

• Back mirror wiper and Latch and stricker reinforcements.

They are each 1.5mm thick with 0mm clearance for welding to inner panel.

Positioning of Latch & striker/ Latch Trajectory:

Backdoor is the swinging part which rotates about hinge axis.  The position and orientation of latch striker is important for proper opening and closing of the backdoor. The positioning is done by sketching a circle with center as the axis of the hinge which passes through the striker at appropriate position with respect to inner panel. 

We have followed here Top Down Approach.

Full Assembly.

Draft Analysis,

Reinforcement Draft Analysis.