Design of backdoor

REPORT

ON

CAR BACKDOOR

UNDER THE GUIDANCE

OF

SKILL LYNCE

AIM:-To Deisgn Sheetmetal panel of backdoor from the provided skin data with all the design rules into cosiderations.

INTRODUCTION:-A backdoor of car also known as tail gate is a commodity which normally serve the purpose of covering the car from the rear end .but there are more function that come with it which has to be considered while making a design of the same like rear visibility criteria and boot space . This part is usually designed keeping the master section of the rear roof rail because of the sealant flange and also various other consideration ,as it is also in contact with side body of the car.

THEORY:- Before starting the design of backdoor , we have to decide which type of backdoor we have to design becouse this step includes the hinge axis . this axis is the one about which the backdoor will open and close . there are three type of backdoor.

• Top Mounted
• Side Mounted
• Bottom mounted

BACK DOOR ASSEMBLY:-

• Inner panel
• Outer panel
• Hinge and its reinforcement
• Wiper motor reinforcement
• Latch & striker and its reinforcement

it is needless to say that the hinge axis will be at specific position where the tail gate is mounted. This initial step us to determine the position of latch and striker.

REPAIRING INPUT:-

The first step is to organize the input skin data as upper outer surface and lower outer face . but before that we have to check for any irregularities in the surface and repair if and sew them together.

SEALING FALNGE

Usually we will take reference from the roof master section for the sealing flange,but as its was not available we have made entire sealing flange in this model.The space occupied by the rubber sealant is usually in the range of 15mm-25mm.

25mm is the open condition ,so we made maintained that distance between inner panel and the sealing flnage .once this flange is made we make a connecting flnage on both side of it and complete this flange to be joined with inner panel .

INNER PANEL:-

The shapes of the inner panel is same as that of the outer panel up to the windshield surface .after that we have to make space for various componenets such as latch and striker motor etc. so we make proper curved surface at the lower side so that we avoid kinks at the mirroring plane . Once the main body is ready . we have to decide the design of the following things:

• Mastic region: Whether we have to design it as a big once at a single region in the centre or two small regions.
• Emboss: we have to creat proper emboss either Y or V or combination of both diverge the force.
• Latch & striker motor space : This will be mounted on one side of the inner panel, but we must make a similar cutout on both the side keeping centre of gravity in mind.
• Material cut -out :-Due to sample space ,we should remove the material from few region to reduce weight of the inner panel.

There are few mounting which we have to keep in mind and make reinforcement for the same:

• Hinges : This model is made such that the backdoor will be mounted on the roof , so the hinges mounting emboss will needed somewhere on the side .
• Wiper motor : The backdoor will also have a wiper whose motor is to be mounted somewhere .As only single wiper will be present , it is common to gives this in the middle near windshield.
• Latch and striker : It is the one which locks and unlocks the backdoor and as the backdoor rotates on the hinge axis , this must be present only .

Once all these design is made , we moves on to makes the mirror of model-in order to make it complete . After mirroring the inner panel a handle mounting space is provided .after the detailing work is done ,it is thickened with the thickness of 0.65mm.

MASTIC REGION:-

Inner and outer panel is joined using hem , but to make this bond stronger we introduce a paste between them which becomes like a rubber after solidifying .

This paste cover about 4mm to 5mm . thus we must have a strucure which is projected from the inner panel towards the outer panel and this must be around 5mm away feom the outer panel to serve its purpose.

EMBOSS:This feature helps to incease the strength and reduce witherness of the backdoor. It must be projected towards the inner panel so that in case of rear crash,this should come in contact .Apart from increaseing the strenght of the panel , its shapes also help to diverge the force outwards. This definitely helps to atleast reduce the net force which is directed inside the car . for diverging the force, we popularly use Y or V emboss

LATCH & STRIKER MOTOR MOUNTING: This motor operates the opening and closing of the hood.But if we make a cut-out for this motor at only region, then it will cause imbalance in our model and the centre of gravity will shift.Hence to maintain CoG we create similar cut-out in the other side also.In the given image,motor will be mounted on the left side(with mounting holes) and a similar cut-out is made on the other side.

REINFORCEMENTS:-

HINGE REINFORCEMENT:-

GAS STAY REINFORCEMENT:-

WIPER MOTOR REINFORCEMENT:-

LATCH AND STRIKER:-

DRAFT ANALYSIS OF INNER PANEL:-

HEMMING: Hood outer panel and inner panel are joined together using hemming process.In this process the outer panel is wrapped around inner panel from all the sides to restrict its movement.This is done using rollers.The following link is to the video of hemming process.

As in this modelupper and lower are separate components and the part is complex unlike hood panel, creating a hem in a single step is not possible.Hence a different approach is followed while making the hem.

1.First the outer panel is offset by a distance keeping the thickness and direction in mind.

2.The sheet is trimmed so as to get a flange of 15mm width.

3.Then a bride curve is made betwwn outer panel and the hemming flange.This curve will act as primary curve for us.

4.Then multiple swept surfaces are created to get hem like surface.

5.Everything is sewed together to get single outer panel.

FINAL MODEL:-

CONCLUSION: A backdoor with proper design rules and industry standards is created

LINK OF BACKDOOR-https://drive.google.com/file/d/12UXezFBCkcQWSqBebnbt4GJP-jCG2T1P/view?usp=sharing