Design of backdoor

Design of Backdoor

Objective: To design Back door of car using the given styling surface.

Intruduction:

A door is a hinged part which is used for entry and exit of the vehicles. Back doors are one of the type doors of the vehicle which are located next to the passenger seat which provides access to the luggage compartment. In most of the cars, these back doors are operated with the help of gas stay which in turn reduces the effort required to lift open the door. Some luxury cars have powered backdoor which in turn is driven by an electric motor. This kind of system is also called a powered trunk lid system. Hatchback or station wagons are sold as 3 door or 5 door models. In this case, the rear hatch is classified as door this is because it enters the passenger compartment. The naming is mainly used in Europe countries. In case of safety, the back door designed should meet the safety requirement for the rear collision.

Functions of the Backdoor

1.It protects the occupants and luggage from getting damaged.

2.It houses assembly of tail lamps, wiper motor and other components.

3.It serves as entry and exit point for luggage/passengers.

4.It houses windshield glass which helps in rear visibility.

5.Parking sensors, rear view camera are mounted on it.

Types of Backdoor

1.top mounted

2.side mounted

3.bottom mounted

• Top mounted:

  These type of back doors are used in a station wagon, pickup truck and some other sports utility vehicles. Today’s modern cars use top mounted tailgating systems which are both powered and also gas stay supported. These tailgates provide greater rear visibility compared to other types.

  

• Side mounted

It is generally used in van type MPVs, SUVs, pickup truck vehicles. These side mounted door/barn doors are a lot easier compared to top mounted ones. These doors are generally small in size and can be easily accessed. These doors are more convenient for the goods handlers carrying lengthy objects, long pipes where one door is kept open. It also saves accidental head impacts. It is a lot easier to load /unload things in vehicles having side-mounted doors.

• Bottom mounted

Bottom type or split type backdoor system is used in estate type cars, pickup trucks and some luxury SUVs. These are most convenient type of backdoor in which the bottom split is used as a support or even as a table for the touring people.

MANUFACTURING METHODS:

Recently, there have been two approaches to reducing automobile weight. One is by using material lighter than steel and the other is by redesigning the steel structure. Although the former seems very effective, it is very expensive so that it may only be used for an expensive automobile. Therefore, the automobile industry is trying to use steel, which is not costly and recyclable. Lightweight steel can be achieved by improving the performance of the structure or adopting new manufacturing techniques. One of the efforts is the ULSAB (ultra-light steel auto body) concept.

ULSAB suggests three main weight reduction techniques such as hydro-forming and the tailor welded blank (TWB).l

GIVEN STYLING SKIN FOR BACK DOOR DESIGN:

BACK DOOR ASSEMBLY:

The back door assembly

• outer panel
• innerr panel
• Hinge reinforcement(Left&right side)
• Gas stay reinforcement(left&right side)
• Wiper motor reinforcement
• Latch/striker reinforcement

1) Outer panel

It is the outer styling skin surface of the back door. It is provided with multistage coatings which has property of scratch resistance, rust prevention etc. It is wrapped around the inner panel through hemming process.

it consits of 2 parts

1.upper part

2.lower part

Hemming: Hemming is a forming operation in which the edges of the sheet are folded over another part in order to achieve a tight fit. Usually hemming operations are used to connect parts together, to improve the appearance of a part and to reinforce part edges. In car part production, hemming is used in assembly as a secondary operation after deep drawing, trimming and flanging operations to join two sheet metal parts (outer and inner) together. Typical parts for this type of assembly are hoods, doors, trunk lids and fenders.

2) Inner Panel

The inner panel is one of the most important components of backdoor assembly. It provides strength and helps in dissipation of forces outside the part with the help of embosses made on it. It helps in mounting of accessories like hinges, wiper motor, gas stay, latch & striker etc.

The inner panel is produced by either casting or through Deep drawing process.

Mostly aluminum part is casted, steel inner panel are manufactured by deep drawing process. If deep drawn, there must be a tooling direction through which that panel must be deep drawn.

Sealing Flange: It is that section of the inner panel which enables the backdoor to sit over the rear body side of the car. Its design is important as it decides how a backdoor is mounted on the rear body side of the car and also restricts any external matter to enter inside the vehicle.

Mastic Sealants: As we know the outer panel gives the aesthetic look to the vehicle, so we can’t use bolting or spot welding or any other joining technique which damages the aesthetic looks of the panel. Thus mastic sealants are used for joining the Inner panel elements with outer panel. A maximum gap of 5mm is to be maintained in between parts where mastics are to be applied.

Reinforcements

Reinforcements are generally placed to increase the strength of the panel in localized areas which is relatively small compared to sheet metal parts for absorbing loads imposed thereon and dissipating such loads throughout the panel assembly to help maintain rigidity of the panel assembly. The reinforcements are usually 1-1.5mm thick as opposed to 0.75mm thick panel used in this part

Hinge Reinforcements:

Hinge is a pivot mechanism which supports the total weight of the backdoor. So reinforcements are added for strength and rigidity.

Gas stay reinforcements

Gas stay is used to lift the backdoor automatically and is used to support the backdoor in its open position. It can be of Two types Semi-automated and fully automated.

Wiper Motor reinforcement

Wiper is used to wipeout the dust particles/water on the windshield glass which affects the rear visibility. It is actuated by the motor which is mounted on the inner panel. Due to vibration and heat of the motor, inner panel gets deformed which results in loss of strength & rigidity of the panel thus leading to poor NVH. So reinforcement is provided to avoid these conditions.

Striker reinforcement

In the bottom part of the panel emboss is created for placemnet of latch and striker assembly. There is over slamming and abusing while opening and closing of the door, thus arising the need for reinforcement to be placed.

position of striker:

Backdoor is the swinging part which rotates about hinge axis. The position and orientation of latch striker is important for proper opening and closing of the backdoor. The positioning is done by sketching a circle with center as the axis of the hinge which passes through the striker at appropriate position with respect to inner panel.

Assembly of back door:

draft analysis:The every part is manfactured or forming by the required draft angle if the draft angle is low the tool wear is increased and we can produce less number of products.

conclusion:The design and assembly of back is completed as per the requirements.