Design of backdoor

BACK-DOOR DESIGN

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.

Software Used:
NX CAD

Backdoor Introduction:

An automobile back door or Tailgate is the panel that covers the boot (or trunk) of an automobile. It enables access to the main luggage compartment. A hinge allows the boot lid to be raised, while devices such as springs or gas cylinders hold it up in the open position The Backdoor is an assembly of many parts such as inner panel, outer panel upper, outer panel lower and Reinforcement. Inner panel is attached to the outer panel using mastic sealant.

Total no. of parts in Backdoor are:

• Back door outer panel (upper)
• Back door outer panel (lower)
• Back door inner panel
• Hinge reinforcements
• Gas stay reinforcements
• Latch and striker reinforcements
• Wiper motor reinforcements

Types of doors based on working position,

1. Top Mounted Door
2. Side mounted Door
3. Bottom Door

INNER PANEL:

Car backdoor inner panel is made of either steel or alumminium.Most of the luxuary car's inner panel are made of aluminium because of is properties.But the cost of aluminium is high.

	STEEL	ALUMINIUM
PARTS	Parts are stamped	Parts are casted
REINFORCEMENTS	Necessary	Can be neglected
THICKNESS	Constant	Can be Varied
COMPONENTS	More	Lessin number
WEIGHT	More	Lighter
COST	less in cost as compared to Aluminium	More as compared to Steel

Cost of aluminium is more as compared to steel .TO easiy understand , the cost of aluminium for inner panel is higher than the cost of all parts of backdoor together.

Different Sheetmetal processes used for manufacturing the Back Door

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.

1. 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.
2. 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:

• Aluminum 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:

1. Conventional die hemming: In conventional die hemming, the flange is folded over the entire length with a hemming tool.
2. Roll hemming: In roll hemming, the hemming roller is guided by an industrial robot to form the flange.

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

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

3. 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.

Load Case Analysis

OUTER UPPER PANEL DESIGN

OUTER LOWER PANEL DESIGN

TOOL DIRECTION

INNER PANEL

Improve the strength of the inner panel and to reduce the weight 'Y' type emboss and other cut-outs are created. Also, for Latch and Stricker mounting cut-out is created. This cut-out is also done on other side of the inner panel to maintain the centre of gravity of the Back door.

Another Emboss is created for Wiper motor mounting.

Hinge Reinforcement

Gas Stay Reinforcement,

Wiper Motor Reinforcement,

Latch & Stricker Reinforcement,

Hemming ,

For positioning the Latch & Stricker, we have to create a trajectory passing through a midpoint of line/ axis of two hinge mounting holes,

Draft Analysis:

Conclusion

Thus the back door was designed from the given styling surface and Draft analysis is also done on the inner panel to check the manufacturing conditions. In this challenge i learned to design the Inner panel, the Outer panel, Wiper Motor reinforcement, Hinge reinforcement, Gas Gtay reinforcements, Latch and Striker reinforcement and its position.