Design of backdoor
OBJECTIVE:-
Use the provided styling surface to come up with a back door design, use appropriate design methodologies, and provide the necessary reinforcements and embosses.
INTRODUCTION:-
Back door is provided in a car to protect the rear passengers at the time of collison and also to cover the lugage compartment of the car.It is a swinging or closer part like hood and side door. We give a curve to it to provide strength because flat surface is less resistant to a force.
At first we have to decide the hinge axis then the latch and striker point then we join the trajectory to decide the opening and closing motion of this and find out the door design.We have to decide the rear visibility and lugage area, more thinner the backdoor is more we get lugage area.
While designing backdoor we should maintain a proper depth/gap inside the backdoor to mount the latch and striker motor,wiper motor and we should provide embosses to add strength and disipate the force outside of the car at the time of collision. We join the parts and components by hemming, spot welding and mastic. Reinforcements are provided at where the strength is less.
To manufacture backdoor there are 2 main material comes into consideration Aluminum and steel. Aluminum is lighter in weight than steel but it is more expensive and we can go to less draft angle with aluminum due to this advantage we can increase the lugage area so the material selection is a very important at its dependent on the budget of car.
COMPONENTS OF BACKDOOR:-
1) Outer Panel
2) Inner Panel
3) Reinforcements
4) Gas stay
5) Wiper and wiper motor
Outer Panel
Outer panel is designed for the aesthetic purpose of the car, Rear lamp, windshield, wiper and number plate are placed on it.
Inner Panel
We design the embosses, and gave some cut out to place the various component such as latch and striker, wiper motor on the inner panel. This U/V structure emboss are designed to dissipate the force outside of the car and the center hole is called axis hole, This is to place the wiper motor.
Reinforcements
Hinge Reinforcement- Hinges are allow the backdoor to open and close in a proper axis. Reinforcements are provided to strengthen that part.
Gas Stay Reinforcement- To provide strength the backdoor at the open position reinforcements are provided to the gas stay part.
Wiper motor Reinforcement- vibration creates while wiper motor is running. To keep that motor is position reinforcement is provided.
Striker Reinforcement- Their might be over stretching or huge amount of force are accumulated while opening and closing the door so to protect the latch and striker reinforcement is provided.
Gas Stay
It is a rod that use to keep the backdoor open. It has 2 types- Semi automated and power stroke. Semi automated need the human force to lift the backdoor then it keeps the backdoor open while the power stay has power spindle which automatically lift the backdoor and keeps it open and closes also.
Wiper and Wiper Motor
Wiper is use to clean the windshield of the backdoor for better visibility of rear side and wiper motor runs the wiper automaticaly.
STRIKER POSITION
The axis circle of backdoor opening and closing is shown below. We need to place the hinges and striker in such a way that the hood will open in this axis. If the hinges and striker is placed right the door will open smoothly.
HEMMING
Hemming is the joining process of two component by folding the edge one upon another and some relifs are provided at the corners.Between inner and outer panel there is 0.2mm gap is provided to apply the hemming glue.
MASTIC SEALANT
This region is given to apply the mastic for the joining of outer and inner pannel. We cannot go for spot welding here, because it affect the aesthetic of the car so we apply mastic for the joining.
DRAFT ANALYSIS
FINAL BACKDOOR DESIGN
CONCLUSION
This backdoor design is created in NX CAD software by using proper design methodologies and requirements. At last it has been given 0.75mm thickness to outer and inner panel and 1.5mm thicknes to all the reinforcemnents.