Design of backdoor

AIM-Provided styling surface to come up with a back door design, use appropriate design methodologies, and provide the necessary reinforcements and embosses.

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 rear of 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 electrically operated. Ii 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 uopn the design of the trunk and material used, flenges, embosses, type of joining of inner panel and outer panel etc.

Types of doors based on working position,

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

The back door is operated by two types of comodities.

1.electrically operated

2.gas stay powered

The main purpose of these mechanisims is to open the back door without heavy efforts, because the backdoor have different parts and the weight of the back door is high, so we are not able to open the back door manually, so we introduced these two types comodities. and these also decides the premium of the car, mostly the electrically operated used in premium cars.

1.gas stay powered

Back Door Assembly:

• Inner panel
• outer panel
• hinge and its reinforcement
• wiper motor reinforcement
• latch & stricker and its reinforcement
• gas stay reinforcement

The major problem in back door is material selection. mostly in past days steel is used, but it makes a very problems the steel parts have heavy weight,so it reduces the fuel economy, insted of steel presently in high end cars aluminium is used, the main objective of aluminium it have less desnser material and its sutaible for complex shapes, and it also gives the thcikness locally because it it done cating, in case of steel we used deep drawing operation. there are some of the advatanges and disadvantages are there

so by using of aluminium we can reduce the number of parts and assembly involvement. and it is castly material.

these are the certain tests are done in back door,not only back door all components must pass these tests but different components have different test because of the functionaly.

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 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.

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.

• Inner Panel

The inner panel, as the name suggests, is the inner part of the door. It is where most of the reinforcements and components are mounted. It is manufactured either by casting (aluminum) or sheet metal stamping (steel). Thickness of inner panel is 0.75 mm.

Outer Panel UPPER

As the name suggests, it is the outer part of the rear door and is mostly responsible for aesthetics of the vehicle. Outer and inner panels are connected by mastic sealants in center and by hemming process at edges. The outer door handle and in some cases, the number plate may also be installed on the outer panel of the back door. We have considered a 2-part outer panel for our design, outer upper panel and outer lower panel prospectively. Outer panel is manufacture by stamping sheet metal. Thickness for outer panel is 0.75 mm.

Outer Panel LOWER

Latch Striker Path

TOOLING AXIS

• Reinforcements

Reinforcements are provided to provide support and add extra Material to the sheet metal part to increase its strength near component installation regions and minimize the impact of collisions. We have considered following reinforcements during our design. The reinforcements maybe manufactured by stamping. Thickness of all reinforcements is 1.5 mm.

LH Hinge Reinforcements

LH Hinge Reinforcements

Latch Striker Reinforcement

Wiper Motor Mounting Reinforcement

Draft Analysis

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.