Challenge

Design of backdoor

RRaja Narendra Bandaru20 Jul 2021

BACKDOOR DESIGN

The backdoor or tailgate is the rear most part of the automobile which opens upwards,downwards or sideways to give access to the luggage space or seating area. In most of the cars the backdoor opens upwards. It is hinged to the roof and a gas stay support fixed at the body side outer for keeping the backdoor in open position. In cars with back door opening sideways, these are hinged to the body side and the gas stay is fixed at the bottom outer for keeping the backdoor in open position.

fig1- Back door hinged to the roof fig2- Back door hinged to the body side

The material used in making the backdoor of car is mainly steel but nowadays Aluminium is also used in making the panels.

The main advantage of Aluminium over steel is that the density of Aluminium is very less as compared to steel so it reduces the overall weight of the car. But Aluminium is costly as compared to steel.

The main parts of the backdoor are:

Outer Panel

Inner Panel

Hinge Reinforcement

Gas Stay Reinforcement

Wiper Motor Reinforcement

Latch and Striker Reinforcement

OUTER PANEL:

The class A surface of the outer panel is provided to us by the styling team. From this surface we have to develop the inner panel and all the other parts and finally assemble them.

The outer panel provided by the styling team looks like-

The outer panel has which is provided has to parts namely upper and lower.

UPPER-

LOWER-

The parts needed to be developed a little and the flange which is having a contact will be spot welded to maintain the contact between the upper and lower parts of the Outer panel.

The outer panel joins the inner panel by Hemming process and sometimes may be welded to stay put.

The whole Outer Panel after symmetrying looks like-

The Outer Panel after thickening looks like-

INNER PANEL:

With the outer panel as parent the inner is created in this way. Firstly a sealing flange has to be created because the sealing flange is the only portion closes the car and protects the cabin from dust, rain, noise and all the other factors.

To create the inner panel we need to have the inner panel surface which we can get from the outer panel offset.

The sealing flange is created and it looks like

The sweep surface has to be created from the outer edge of the flange which is going to get connected with the outer panel's offset which is going to be the inner panel.

This portion has been created by trimming the flange portion with the offset.

After this entire flange creation process, next we need to create the windscreen panel which is going to be in the inner panel itself. This panel accomodates the rear wind screen.

The panel needs to be developed for parts accomodation like Wiper motor, Rear Signal Lights.The panel aslo needed to be developed to make sure that it can be hinged to the roof and also be provided with Latch and Striker Slots and Gas stay slots too. Over all The inner panel after Developing looks like-

The panel after developing is Symmetried to get the full Inner Panel

The inner panel where it is provided with slots for assembling the latch and striker, Gas stay and Hinges are to be provided with Reinforcements so that they can withstand the load and have the proper strenght at all times.

The panel after thickening looks like-(The part has to be thickened outwards)