Design of backdoor

AIM:

To Design the outer upper and lower panel, inner panel with the necessary reinforcements by following the Master section with the design parameter for the given class A surface.

INTRODUCTION:

The trunk (North American English) or boot (British English) of a car is the vehicle's main storage or cargo compartment, often a hatch at the vehicle. It is also called a tailgate. These doors can be operated manually or electric powered. In most of the luxury cars door is electically operated. It involves a very major role during rear crash cases. So our design must be obey crash requirements. the institute of highway saftey analyse the diffrent accidents and they set a test to rate our car. So these rating depends upon the design of the trunk and material used, flenges, embosses, type of joining of inner panel and outer panel etc

Types of the back door

Top-Mounted:

This type of back doors is used in a station wagan, 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 vsibility compared to side-mounted or bar doors which have center pillars in it.

Side Mounted Doors:

As the name signifies side-mounted doors are the one which is used in the van type MPVs, SUVs, pickup truck vehicles. These side-mounted doors or barn doors are a lot easier compared to top-mounted doors. These doors are generally smaller in size and can be easily accessed

Types of mechanisms for Rear Door:

Gas stays:

Gas stay types backdoor/liftgate/tailgate is an ideal and most commonly used tailgate mechanism fron lower segment car to luxury car segment. The ideal components of tailgate consist of a hinge, door, gas stay and some rubber beadings for sealing of door

Powered lift sysytem:

Power trunk lid system is another sophisticated way of trunk/liftgate opening mechanism which is to automatically open and close of the trunk/liftgate and release of the latch by the touch of a button

Different types of Sheetmetal operations are done in 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 contant with the punch. When the metal specimen is flat piece of sheet metal used in forming and finish the product. Initially the puch moves in downwards direction. The outer rim of blank is subjected to pure radial drawing (drawing toward in vertical axis ) between die and blank metal. The become a bend and sliding over die and also stretched between die and punch. The metal in vicinity of puch head and contact with it bend and slide over radil 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 puch. 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 foriming 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 tow sheet metal parts (outer and inner) together. Typical parts for this type of assembly are hoods, trunk lids and fenders.

These are various types of hemming operations:

1. Convertional 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.

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 simillar 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

Components to create:

1. Outer Upper Panel
2. Outer Lower Panel
3. Inner Panel
4. Gas Stay Reinforcement
5. Hinge Reinforcement
6. Wiper Reinforcement

Procedure:

Class A Surface:

backdoor outer upper and lower class a surface has to be repaired according to the smoothness. After repairing the surfaces, the door is divided into two parts as Door Outer Upper and Door Lower Panel.

Outer Upper Panel:

Now, we need to create the Tooling direction for the Deep drawing operation. It shows that all the operations like embossing is done by considering this vector direction and it will help in manufacturing the part

After that we have to create Sealing Flange by offsetting the outer panel to the specific distance.

Then we will be creating the Back door inner panel flange by offsetting the outer surface at a distance considering the sheet thickness and thickening direction.

Then created the connecting flange to join the inner panel and sealing flange.

Then for the windshield panel mounting, windshield panel is created and joined with sealing flange

When the car hits at the rear end, the impact force should dissipate outside for safety. For that we give Y/V emboss which helps to direct the force to the outer end.

Embosses and Reinforcements:

Now to assemble the back door with the vehicle Hinges are used to open and close the door. For that to increase the local area strength we have to design the emboss and provide the appropriate reinforcements to withstand the load acting upon it.