Challenge

Design of backdoor

SSurya Bharathi P14 Jul 2021

Objective :

To Develop the Car Back Door by Using given Styling Surface Method by Automotive sheet metal design.

Software Used :- Nx12

what is backdoor ?

Backdoor is one of the type of door of the vehicle which is located next to the passanger seat which provides access to the luggage compartment. In the most of the cars, these back door are operated with the help of gas stay which in turn reduces the effort required to lift the door.

Design Consideration-

Rear Visibility
Hinges and gas stays
Fit and Clearances
Boot spaces and accessibility

COMPONENTS OF BACKDOOR:

Inner panel
Outter panel upper
Outter panel lower
Hinge reinforcement LH
Hinge reinforcement RH
Gas stay reinforcement LH
Gas stay reinforcement RH
Wiper motor reinforcement
Latch reinforcement

Types of doors based on working position,

Top Mounted Door
Side mounted Door
Bottom Door
1.Top mounted:

This type of back doors is used in a station wagon, pickup trunk and some of the spot utility vehicles. Today's modern cars use top mounted tailgating system which are both powered and also gas stay supported. These top mounted tailgates provide greater rear visibility compared to side mounted or backdoor which have center pillars in it.

2.Side mounted door:

As the name signifies the side mounted doors are the one which is used in the van type MPVs, SUVs, pickup truck vehicles. These side mounted doors or barn doors are a lot easier compare to top mounted doors. These doors are generally smaller in size and can be easily accessed. These doors are more convenient for the goods handlers for long pipe and lengthy components where one door is kept open. These door also save accidental head impacts. It is a lot easier to load and unload items in the side mounted doors

3.Bottom type:

This bottom type type backdoor system are used in the car type such as car, pickup truck and some luxuary SUVs. These are the most convenient type of back door in which the bottom split is used as a support or even as a table for the tour going people.

Types based on Working Mechanism:

1.Gas Stays type.

2.Powered Lift system.

1.Gas Stay type:

Gas Stay type backdoor is an ideal and most commonly used tailgate mechanism from lower segment car to luxury car segment. The ideal components of tailgate consist of a hinge, door, gas stay and some rubber beadings for sealing of door.

2.Powered Lift System:

Power trunk lift system is another sophisticated way of trunk or liftgate opening mechanism which is to automatically open and close of the trunk and release of the latch by the touch of a bottom. Powered trunk Lift system consists of a power latch, anti pinch switch, PTG assly, PTG main switch. When the switch is pressed in the compartment or outside the power latch releases the latch and the entire backdoor is opened. The anti pinch switch is located in order to avoid accidental hand insertion during the operation of the door.

So now a days most of the car manufacturers are trying to use Aluminium instead of Steel and they reduce the number of parts and weight of the car drastically.

Steel Aluminium

Parts parts are stamped parts are casted

Reinforcement Necessary Can be neglected

Thickness Constant Can be varied

Components More Less in number

Weight More Lighter

Cost Less in Cost As compared to Al More As compared to Steel

Embossing -

Embossing is a metal forming process for producing raised or sunken designs or relief in sheet material by means of matched male and female roller dies, theoretically with no change in metal thickness. Embosses are created to provided addition strength and to direct the forces towards the hindge and body of the car.

For inner panel to act as a good reinforcement, it needs to disperse the stress outwards, hence the emboss was designed In such a way that the forces are directed outwards or away from the center.

Hemming:-

Hemming is the process in which the edge is rolled flush to itself, while a seam joins the edges of two materials. Normally hemming operations are used to connect parts together, to improve the appearance of a part and to reinforce part edges.

Relief is provided onto the part or component in order to remove any stresses developed in a particular area i.e sharp corners that takes place during the hemming process is carried out. Thus corners are rounded or chamfered.

Reinforcement-

In backdoor to accomodate Latch and striker, Hinges & Gas stay we have to remove some material which will result in loss of strength of the material locally. Hence to improve strength locally we provide these reinforcements. The reinforcements provided in the latch and striker area is called Latch and Striker Reinforcements & the reinforcements provided in the Hinge area is called Hinge Reinforcements and reinforcements provided in the Gas stay region is called Gas stay reinforcements.

The various reinforcements in backdoor inner panel,

Hinge Reinforcement

2.Gas stay Reinforcement

3.Wiper motor Reinforcement

4.Latch and Striker Reinforcement

Corner Relief:

Relief helps to control sheet metal material behavior and to prevent unwanted deformation during unbend operations.

Latch & striker & Hinge Positions

For the proper opening & closing of the backdoor, the striker should be perpendicular to the trajectory of the backdoor. Firstly the hinge is positioned and an axis is drawn as shown in the fig.2.0. The Trajectory is derived from the hinge axis and the centre distance from the striker.