Design of backdoor

Design of Automobile Backdoor

AIM: 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:

The backdoor or tailgate is the rearmost part of the automobile which opens upwards, downwards, and sideways to give access to the luggage space or seating.In most automobiles, the backdoor opens upwards. It is hinged to the roof and a gas stay support fixed at the body side outer for keeping the backdoor in the open position The material used in the making the backdoor of the car is mainly steel but Aluminium is most prefered.The main advantage of Aluminium is that the density of Aluminium is very less as compared to steel so it reduces the overall weight of the car.But Aluminium is more costly as compared to steel.

In most of the cars back doors are operated with gas stay which helps in reducing the effort to lift the tail gate and some premium cars backdoors are power and electronically controlled also known as powered tail gate.There are hatchbacks in which the backdoor is also considered as a door and called as 3 door or 5 door hatch and station wagon,usually followed in europian markets.Backdoor design should also be considered for safety and safety requirement should be meet for rear collision. 

Types of doors are Top-mounted door,Side-mounted door,Bottom Door

1.TOP MOUNTED DOOR:

            This type of back doors is used in a station wagon, pickup truck and some of the sport utility vehicles. Today’s modern cars use top-mounted tailgating systems which are both powered and also gas stay supported. These top mounted tailgates provide greater rear visibility compared to side-mounted or bar doors which have canter pillars in it. 

2.SIDE MOUNTED DOOR:

•  It 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

2.BOTTOM MOUNTED DOOR:

It 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.

Different processes used for manufacturing the Back Door:

Deep Drawing:

The metal deep drawing process is an effective method of manufacturing cups, cans, and other similar deep drawing products. The deep drawings having 2 main categories.

First-stage drawing: The blank shape of metal is placed on the die and in contact with the punch. When the metal specimen is a flat piece of sheet metal is used in forming and finish the product. Initially, the punch moves in a downward direction. The outer rim of the blank is subjected to pure radial drawing (drawing toward vertical axes) between the die and blank metal. The metal becomes a bend and slides over the die and is also stretched between die and punch. The metal in the vicinity of the punch head and contact with it bend and slide over the radii and stretch over the punch head.

Redrawing: The components drawn from the first stage again it is redrawn convert into more depth to form a cup shape in the die and punch. The second stage of drawing is called redrawing.

  Hemming: It 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. 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 fender

   

PUNCHING:

            It is similar to blanking only the main difference is that, the hole is the required product and the material punched out from the hole is considered as a waste.

BLANKING:

Blanking is a cutting operation of a flat metal sheet and the article punched out is known as blank. Blank is the required product of the operation and the metal left behind is considered as a waste

COMPONENTS OF BACKDOOR:

1. Outer panel
2. Inner panel
3. Hinge reinforcement
4. Gas stays reinforcement
5. Wiper motor reinforcement
6. Latch & striker reinforcement
7. Mastic Area

DESIGN CONSIDERATION OF A BACKDOOR:

Functional Requirement of Hinge and gas stay 

Rear visibility criteria

Luggage volume area

Crash Analysis

Bend Test, Dent Test, Torsion Test & Endurance Test

Rear Crash Regulation

Gap and flushness Requirements

DESIGN OF BACKDOOR:

• The Outer Panel is the styling surface of the back door design. Other components of the backdoor are designed with reference to the outer panel surface. It acts as the outer cover & deals with the aesthetics of the car.

In this design outer panel is divided into two-part.

A.Outer Upper Panel: This outer panel designed based on visibility criteria and proper reliefs provided at the corner for hemming operation .The thickness of outer panel is 0.75 mm.

B.Outer Inner Panel:Back door Inner panel  designed based  on hinge, gas stay, wiper motor position and reinforcement as well as visibility criteria .Suitable tooling direction is created  for trouble free manufacturing process.In this design stamping operations created based on this tooling direction. Embosses are provided in this design for force dissipation. In this design appropriate clearance given in mastic areas .The inner panel thickness is 0.75 mm.

• Mastic Area 

Mastics sealants used for  joining of outer panel and inner panel. It increase the strength of back door and good NVH. So accurate clearance given for mastic sealant.

• Hinge reinforcement

In this design hinges provided on the top side of the door. Appropriate  reinforcement given for hinge mounting areas to improve the strength.

• Gas stay reinforcement    

Gas stays support the weight of the back door while they are open. More load act on this region ,So suitable  reinforcement provided  for better strength.It is spot  welded on the inner panel.

• Wiper motor reinforcement  

Reinforcement provided in this region for fixing the wiper motor.

Latch and Striker Reinforcement:

The Latch & Striker together form the locking mechanism of the backdoor with the car. Due to regular opening, closing, and over slamming of the backdoor, there is stress developed in the Latch & Striker area. To recoup for the same, reinforcements are added in this area.

Trajactory axis for striker

Skin data given to develop the backdoor 

DRAFT ANALYSIS:

1. The draft analysis was performed for the tooling direction created at first and checked that the model is suitable for manufacturing.
2. Then to get a complete green portion the required changes to the draft angle of the embosses were carried out by optimizing the model.
3. The Draft Analysis command is used to detect that the part drafted will be easily removed or not.
4. This type of draft analysis is performed based on colour ranges.
5. The identifying zones on the analysed element where the deviation from the draft direction at any point, corresponds to specified values.

 

Screenshots of the backdoor model 

Door Inner Panel 

Assembly of the backdoor

Conclusion:

A back door design using the styling surface, appropriate design methodologies, and provide the necessary reinforcements and embosses has been completed.

Thankyou.

Disclaimer for grading this challenge

Please note that due to file size being more than 20 MB, I am having error in uploading the zip file to challenge box and the error shown screenshot image is shown below.

 

Therefore the model is attached to google drive and the link is provided below for grading. Thank you. 

https://drive.google.com/file/d/1zheG4Li5RK_uioxuIdGuKD7hrwlYfCNy/view?usp=sharing