Design of backdoor

Design of back door

Aim: To design a Backdoor of the car on sheet metal using he appropriate design and provided skin data by considering design rules.

Objective: To design the backdoor with design methodologies and provide the embos, reinforcements in the inner panel and side relief in outer panel to increase the strength.

Theory of back door:

The Back door of a car is a component which hinges at the back of the car to cover the boot space or luggage area, but there are more functions 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 considerations, as it is also in contact with the side body of the car.

It has back lights/ Tail lamps and Braking lights which is termed as "Third brake light" mounts on it, rear windshield fixes between inner and outer panel, in some back door spare wheel can be mounted on it, sometimes car registration number plate mounts on it and it gives a complete closed design to the car.

Backdoor images:

Back Door Assembly:

Inner panel

Outer panel

Hinge and its reinforcement

Wiper motor reinforcement

Latch & striker and its reinforcement

Deep Drawing:

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

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

Redrawing: The components drawn from 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 as redrawing.

Embossing:

Embossing is a metal forming process for producing raised or sunken designs or relief in sheet materials by means of matched male and female roller dies, theoretically with no change in metal thickness or by-passing sheet or a strip of metal between rolls of the desired pattern. Metal sheet is drawn through the male and female roller dies producing a pattern or design on the metal sheet. Depending on the roller dies used, different patterns can be produced on the metal sheet.

Materials commonly used in the metal embossing process include:

Aluminium alloys

Steel alloys

Zinc

Copper

Galvanized steel

Brass

Cold rolled steel

Hemming:

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.

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.

There are various types of hemming operations:

Conventional die hemming: In conventional die hemming, the flange is folded over the entire length with a hemming tool.

Roll hemming: In roll hemming, the hemming roller is guided by an industrial robot to form the flange

Open Hem: A Hem has a full round feature and a return flange. In open hem bend angle is equal to 180 degrees.

Tear drop Hem: In tear drop hem the bend angle is greater than 180 degrees.

Closed Hem: Hems without any inside radius are called as closed hem. Closed hems are not recommended if the hem geometry is to be painted or if the material used is SST or Aluminium.

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.

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.

Enter image description herenter image description here what is the difference between piercing and blanking in sheet metal? - Quora

SPOT WELDING:

Spot Welding is a form of resistance welding also known as Resistance Spot Welding (RSW). Spot Welding involves using heat produced by resistance to an electrical current to join materials together. The current heats the materials to a point where they become malleable. The use of strong pressure bonds them together.

Another form of resistance welding is Projection Welding. This process involves fusing a fastener’s embossed or coined projections to the metal base material to form a weld. As the materials never melt, they do not intermix. This means the resulting weld is more like a forging of the materials.

Spot welding is only suitable for a small selection of base materials. Low carbon steel is the most suitable material for spot welding. This is because it is more resistant to electricity and has a lower thermal conductivity than the copper electrodes used to create the required electrical current.

High carbon steels and aluminium alloys can form brittle welds that don’t last with the spot welding process. Pure aluminium can qualify for spot welding but requires higher current levels. This is because it has a lower resistance to electricity than low carbon steel.

The outer panel upper and outer panel lower are joined through the spot welding .So there must be no gap between the outer panel upper and outer panel lower.

Design of Back door in NX CAD:

Door parts thickness is given below,

Outer Panel - 0.75 mm

Inner Panel - 0.75 mm

Reinforcements - 1.5 mm

Parts of the Back Door

Back door outer upper panel:

Back door outer lower panel:

Back door outer inner panel:

Back door reinforcement :

Draft analysis

Back door inner panel:

CONCLUSION:

Thus, for the provided styling surface of a back door design, I used appropriate design methodologies and provided the necessary reinforcements and embosses for the Back Door design. Thus designed a back door.