Design of backdoor
Aim :-
To develop the car backdoor by using given surface method by automotive sheet design.
To develop the car backdoor by using given surface method by automotive sheet design.
BACKDOOR :-
A backdoor is found at the hind end of the car which provides access for the boot space to store luggage.,spare wheel
etc.These doors may be operated mannualy or electric powered.In most of the luxuary car is electrical powered.
Back Door also called as 'Hatch', or 'Tailgate', 'Trunk-lid', 'Boot-door' is essentially the 5 door in a very 4-door car. It's the
rearmost a part of the vehicle which supplies access to the trunk and has mounts for electric motor, tail lamps, hinges for
supporting its weight in opened position, gas stays which help with its opening and keeping it open, radars and cameras
etc.
A backdoor is usually made up of 1 inner panel and 2 or 3 outer panels joined together by hemming and spot welding
wherever necessary
wherever necessary
The material used for backdoor varies as per the value range of the vehicle. Most of the low cost vehicles use steel because it is
cheaper and use parts that are stamped using moulds. These parts are usually of uniform thickness and reinforcements
are added to enhance local strength where needed. The premium vehicles use aluminium parts which are usually die
casted and hence can have variable thickness. This removes the necessity of reinforcements hence keeping the load
even lower as aluminium parts are lighter as compared. On the contrary aluminium is dearer than steel hence
its applications are limited in cheaper vehicle. Currently because of the extensive use of plastics trims and plastic parts the
cost of aluminium is affordable for the manufacturers all told price brackets.Use of aluminium reduces the weight
of the component and hence the vehicle improving its fuel efficiency.
Reinforcements :-
As mentioned for local strengthening reinforcements are usually provided. rather than making the full panel off a
thicker sheet, a thinner sheet with thicker local reinforcements wherever needed is preferred. The reinforcements are
usually 1-1.5mm thick whereas the panel itself is 0.55- 1 mm thick.
cheaper and use parts that are stamped using moulds. These parts are usually of uniform thickness and reinforcements
are added to enhance local strength where needed. The premium vehicles use aluminium parts which are usually die
casted and hence can have variable thickness. This removes the necessity of reinforcements hence keeping the load
even lower as aluminium parts are lighter as compared. On the contrary aluminium is dearer than steel hence
its applications are limited in cheaper vehicle. Currently because of the extensive use of plastics trims and plastic parts the
cost of aluminium is affordable for the manufacturers all told price brackets.Use of aluminium reduces the weight
of the component and hence the vehicle improving its fuel efficiency.
Reinforcements :-
As mentioned for local strengthening reinforcements are usually provided. rather than making the full panel off a
thicker sheet, a thinner sheet with thicker local reinforcements wherever needed is preferred. The reinforcements are
usually 1-1.5mm thick whereas the panel itself is 0.55- 1 mm thick.
Backdoor parts thickness value used in this design:
1. Outter panel - 0.75 mm
2. Inner panel - 0.75 mm
3. Reinforcements - 1.5 mm
Design Consideration for Backdoor Inner Panel:
1. Rear Visibility.
2. Support structures like hinges and gas stays.
3. Mounts for wiper motor, tail lamps, and other wiring loops.
4. Fit and clearances.
5. Boot space
6. Rear crash regulations and requirements.
7. Sealing and its functions.
8. Joining techniques like hemming, spot welding etc.
1. Outter panel - 0.75 mm
2. Inner panel - 0.75 mm
3. Reinforcements - 1.5 mm
Design Consideration for Backdoor Inner Panel:
1. Rear Visibility.
2. Support structures like hinges and gas stays.
3. Mounts for wiper motor, tail lamps, and other wiring loops.
4. Fit and clearances.
5. Boot space
6. Rear crash regulations and requirements.
7. Sealing and its functions.
8. Joining techniques like hemming, spot welding etc.
Types of Door Opening :
Top mounted door
Side mounted door
Bottom Door
In these project, I designed Top mounted door,So here we discuss mainly about top mounted door only.
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
Plastic trim
Wiper motor, latch reinforcements,hinge reinforcements and gas stay reinforcements are mounted on the inner panel of
the backdoor only.
the backdoor only.
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.Firstly we have to check for any surface discontinuity and
irregularities. Small errors can be rectified but if there is any major error contact the styling team
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.Firstly we have to check for any surface discontinuity and
irregularities. Small errors can be rectified but if there is any major error contact the styling team
Inner Panel:
Considering the class A surface as reference we have to create the inner panel of the backdoor. The most important
part of the inner panel is the sealing flange which decides how the backdoor will be mounted at the rear side of the car.
It also seals the rear side of the car and prevents the entry of dust and water from entering inside the car. The width of
the sealing flange should be at least 25mm.
Considering the class A surface as reference we have to create the inner panel of the backdoor. The most important
part of the inner panel is the sealing flange which decides how the backdoor will be mounted at the rear side of the car.
It also seals the rear side of the car and prevents the entry of dust and water from entering inside the car. The width of
the sealing flange should be at least 25mm.
Embosses and Cut Outs:
The embosses are provided in the inner panel for strengthening the part and also to dissipate the forces in case of rear
collision to the outside of the car.. The cut outs are basically access holes for the fitment of wiper motor and latch and
striker motor. These are fitted mainly after the assembling of the inner panel with the outer panel. Sometimes holes are
also provided in the panel to maintain the CG of the panel
The embosses are provided in the inner panel for strengthening the part and also to dissipate the forces in case of rear
collision to the outside of the car.. The cut outs are basically access holes for the fitment of wiper motor and latch and
striker motor. These are fitted mainly after the assembling of the inner panel with the outer panel. Sometimes holes are
also provided in the panel to maintain the CG of the panel
The inner panel is mainly fixed to the outer panel by the process of hemming but still there will be rattling noise. So to
avoid that extensions are created in the inner panel which is fixed to the outer panel by applying mastic seal. While
designing make sure to give 4-5 mm distance from the outer panel so that mastic seal can be applied in that area.
avoid that extensions are created in the inner panel which is fixed to the outer panel by applying mastic seal. While
designing make sure to give 4-5 mm distance from the outer panel so that mastic seal can be applied in that area.
Embosses for the fitment of hinge, gas stay, wiper motor and latch and striker are created on the inner panel.
Hinge emboss :-
Hinge emboss :-
Gas stack emboss :
Viper motor emboss :-
\Latch emboss :-
Hinge Reinforcement :-
The backdoor is hinged to the roof. The hinge may be fitted outside the backdoor or inside the backdoor.
Reinforcements are designed to strengthen the localised part where the hinge is assembled.
The backdoor is hinged to the roof. The hinge may be fitted outside the backdoor or inside the backdoor.
Reinforcements are designed to strengthen the localised part where the hinge is assembled.
Gas Stay Reinforcement :-
Gas Stay is that part which helps the backdoor to stay in the open position. It is either motor operated or manually
operated
Gas Stay is that part which helps the backdoor to stay in the open position. It is either motor operated or manually
operated
Wiper Motor Reinfocement :-
Wiper is used to to wipeout the rain water falls on the backdoor window.It is actuated by the motor which is mounted on
the inner panel.Due to the vibration and heat created by the motor .the inner panel where the motor is mounted gets
deform and the parts attached to the motor starts to vibrate which leads to poor NVH.So we have to provide the
reinforcement where the wiper motor is placed.
Wiper is used to to wipeout the rain water falls on the backdoor window.It is actuated by the motor which is mounted on
the inner panel.Due to the vibration and heat created by the motor .the inner panel where the motor is mounted gets
deform and the parts attached to the motor starts to vibrate which leads to poor NVH.So we have to provide the
reinforcement where the wiper motor is placed.
Latch and Striker Reinforcement :-
The fitment of latch and striker plays an important role in the designing of backdoor. At first the hinge is fixed, and by
taking the centre point of the hinge axis and the centre point of the latch, draw a circle. the centre of the latch should be
perpendicular to the circular trajectory.
The fitment of latch and striker plays an important role in the designing of backdoor. At first the hinge is fixed, and by
taking the centre point of the hinge axis and the centre point of the latch, draw a circle. the centre of the latch should be
perpendicular to the circular trajectory.
Hemming :-
At the corners the outer panel and the inner panel are joined together by hemming. No type of welding is done because
it leaves a mark on the outer panel and damages the aesthetic beauty of the car.
Hemming is a forming operation in which the edges of the sheet are folded or folded over another part in order to
achieve a tight fit. Normally hemming operations are used to connect parts together, to improve the appearance of a
part and to reinforce part edges
At the corners the outer panel and the inner panel are joined together by hemming. No type of welding is done because
it leaves a mark on the outer panel and damages the aesthetic beauty of the car.
Hemming is a forming operation in which the edges of the sheet are folded or folded over another part in order to
achieve a tight fit. Normally hemming operations are used to connect parts together, to improve the appearance of a
part and to reinforce part edges
draft analysis
tree structure
