Design of backdoor

1. Objective –

To develop back door of the car by using given styling surface and provide necessary embosses and reinforcement to the back door

2. Software used

Siemens NX-CAD

3. Introduction –

Back door of the car is also known as tailgate. This is a critical part for back Impacts occur on the accidents which should be ensure that crash wouldn’t injured the passenger, Back doors consist of one inner panel and two outer panel most of the time. The back doors are made from steel or aluminum based on the budget of the car the material is selected.

The strength of the back door would be stronger therefore reinforcement are not required indeed which will reduce overall weight of the part but aluminum a bit expensive than steel.

Types of doors based on working position,

4. Top mounted door

5. Side mounted door

6. Bottom Door

Back door consists of following parts:-

Inner Panel

Outer panel :

Outer panel Upper –

Outer panel lower –

Hinge and its reinforcement –

Hinge reinforcement
Stay rod hinge reinforcement
Wiper motor reinforcement
Latch and striker reinforcement

Hemming of back door –

Hemming is used to join outer and inner panel by applying glue In between them.

Assembly of back door –

The major problem in back door is material selection. Mostly in past days steel is used but it makes a very problem the steel parts have heavy weight, so it reduces the fuel economy instead of steel presently in high end cars alluminium is used. The main objective of alluminium it have less denser material and its sutable for complex shapes.

Draft Analysis –

Different types of sheet metal operation are done in the back door

Deep Drawing :

Deep drawing (in the context of sheet metal forming) is the process by which a flat sheet of steel istransformed into a deep (often complex) shape, whereby the flat sheet is “drawn in” from the edges and “sucked in” to create a deep shape that otherwise may not be possible using normal metal forming techniques.


[A simple deep drawn cup from a round blank]

The most simple example of a “deep draw” is a basic round cup. The metal forming physics of such a simple shape are well understood, since a cup is defined by just a few critical dimensions such as the diameter and depth. The thickness of the sheet is also a consideration. A deep round cup can easily be drawn from a circular blank by considering the ratio of the blank diameter to the diameter of the cup to be drawn. It was established perhaps more than a century ago that the ratio of the blank/cup diameter controls whether or not a cup shape can be drawn successfully from a sheet of steel.
This table shows “reduction ratios” for simple round cups, for a given thickness, to successfully deep draw just about any size or depth of round cup shape. A round blank can be drawn and re-drawn many times using multiple deep draw operations.


[Table of draw ratios for a successful deep draw]

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:

Aluminum alloys
Steel alloys
Zinc
Copper
Galvanized steel
Brass
Cold rolled steel
3.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.

5.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.

inputs for designing of backdoor:
Outer Panel - 0.75 mm
Inner Panel - 0.75 mm

rienforcement -0.75mm

CONCLUSION:-

The back door outer and inner panel were designed with the help of the styling surface along the tooling direction.and Draft analysis was performed on the inner panel and All the reinforcements were designed and placed at appropriate positions.