Design of backdoor

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.

Back Door Assembly:

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

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• 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.
  3. 

• 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.

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• 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.

  

• inputs for designing of backdoor:

  1. Outer Panel - 0.75 mm
  2. Inner Panel - 0.75 mm
  3. Reinforcements - 1.5 mm

  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 Doo Lower Panel.

• Manufacturing methods:

  Recently, there have been two approaches to reducing automobile weight. One is by using material lighter than steel and the other is by redesigning the steel structure. Althrough the former seems very effective, it is very expensive so that it may only be used for an expensive automobile industry is trying to use steel, which is not costly and recyclable. Light weight steel can be achieved by improving the performance of the structure or adopting by improving the performance of the structure or adopting new manufacturing techniques. One of the efforts is the ULSAB (Ultra Light Steel Auto Body) concept.

  ULSAB suggests three main weight reduction techniques such as hydro forming and the Tailor Welded Blank (TWB)

• he Different panels or regions are as follows:

  1.Inner Panel.

  2.Outer Upper Panel.

  3.Outer Lower Panel.

  Backdoor Assembly:

  1.Inner Panel

  2.Outer Panel

  3.Hinge Reniforcement.

  4.Gas Stay Reniforcement.

  5.Wiper Motor Reniforcement.

  6.Latch and Striker Reniforcement.

• 1.Inner Panel:

  The inner Panel is a component which is used for strengthening the door and it is one of the most important components on which all accessories are mounted like hinges, glass guide channel, mounted trim, latch etc.., The possible method is the integration method. In the integration method, the part is stamped out of a single blank. This reduces the numbertools needed the assembly cost and eliminates any fit ability problem.

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• 2.Outer panel:

  The Outer panel of the back door is similar to other BIW components where it is the aesthetic part of a vehicle. The coating provided is of multi stage which has the property of scratch resistance, rush prevention and smooth and attractive finishes. The Outer panel also has the provisions for the tail lamp, rear fog lamp and also has the provision for lisence plate mountings. Most of the hatch back cars have the provision for wiper motor.

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• 3.Hinge Reinforcement:

  Hinges support the weight of the whole backdoor. Hence a reinforcement are provided here too. Emboss is designed such that the hinges should operated freely. The electrical wiring looms are through the holes along the periphery to keep them hidden.

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• 4.Gas stay Reinforcement:

  An angled or Diabolic emboss is provided for the gas stay mounts. The angle makes it easy to be machined and stamped. It is reniforcement with a thicker sheet.

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• 5.Wiper motor Reniforcement:

  A dedicated space near the window is left for wiper motor assembly. A cavity is placed in the middle of the panel for the necessary components in the assembly as well as other accessories.

  The holes or cavities are placed strategically to accommodate wiring looms, tail lamp mount, and other accessories. Embosses help stiffening the panel and act like local reniforcements. Extensions are provided around holes which are attached to outer panels and acts are crumple zone elements in case of rear impacts.

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• Latch and strikere Reniforcement:

  At the bottom of the latch and striker assembly. Generally a key operated or automatic remotely controllable locking mechanism is used to keep the door closed and open.

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