Design of backdoor

BACKDOOR-

The trunk or boot 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. In India the storage area is known as a dickey (also spelled dicky, dickie, or diggy),. Back doors are one of the type doors of the vehicle which are located next to the passenger seat which provides access to the luggage compartment. In most of the cars, these back doors are operated with the help of gas stay which in turn reduces the effort required to lift open the door. Some luxury cars have powered backdoor which in turn is driven by an electric motor. This kind of system is also called a powered trunk lid system. Hatchback or station wagons are sold as 3 door or 5 door models. In this case, the rear hatch is classified as door this is because it enters the passenger compartment. The naming is mainly used in Europe countries. In case of safety, the back door designed should meet the safety requirement for the rear collision.

Design history-

The trunk or luggage compartment is most often at the rear of the vehicle. Early designs had an exterior rack on the rear of the vehicle to attach luggage truck. Later designs integrated the storage area into the vehicle's body, and eventually became more streamlined.The main storage compartment is normally provided at the end of the vehicle opposite to which the engine is located.

Some mid-engined or electric cars have luggage compartments both in the front and in the rear. Examples include the Porsche 914 and Boxster as well as Toyota MR2. The mid-engined Fiat X1/9 also has two storage compartments, although the rear one is small, easily accessible, and practically cuboid in shape.^[5]

Rear-engined cars like Volkswagen Beetle or Porsche 911 have the trunk in front of the passenger compartment.^[6][7] The Volkswagen Type 3 featured a rear engine design that allowed for a shallow conventional trunk in the rear as well as space in the front for luggage.^[8]

Sometimes during the design life of the vehicle, the lid may be restyled to increase the size or improve the practicality and usefulness of the trunk's shape. Examples of this include the Beetle redesign to the 1970s 'Super Beetle' and the pre-war and 1950s post-war Citroën Traction Avant.

Types of backdoor on working position

1.Top mounted.

2.Side mounted doors.

3.Bottom type

1.Top mounted:

This type of back doors is used in a station wagon, pickup trunk and some of the spot utility vehicles. Today's modern cars use top mounted tailgating system which are both powered and also gas stay supported. These top mounted tailgates provide greater rear visibility compared to side mounted or backdoor which have center pillars in it.

2.Side mounted door:

As the name signifies the 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 compare to top mounted doors. These doors are generally smaller in size and can be easily accessed. These doors are more convenient for the goods handlers for long pipe and lengthy components where one door is kept open. These door also save accidental head impacts. It is a lot easier to load and unload items in the side mounted doors.

3.Bottom type:

This bottom type type backdoor system are used in the car type such as car, pickup truck and some luxuary SUVs. These are the most convenient type of back door in which the bottom split is used as a support or even as a table for the tour going people.

Types based on Working Mechanism:

1.Gas Stays type.

2.Powered Lift system.

1.Gas Stay type:

Gas Stay type backdoor is an ideal and most commonly used tailgate mechanism from 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.

2.Powered Lift System:

Power trunk lift system is another sophisticated way of trunk or liftgate opening mechanism which is to automatically open and close of the trunk and release of the latch by the touch of a bottom. Powered trunk Lift system consists of a power latch, anti pinch switch, PTG assly, PTG main switch. When the switch is pressed in the compartment or outside the power latch releases the latch and the entire backdoor is opened. The anti pinch switch is located in order to avoid accidental hand insertion during the operation of the door.

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.

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.

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PURPOSE TO DESIGN BACKDOOR-

Backdoor are used for luggage area,Drivers can see in backward direction , strenth the vechile

AIM- To Design an outer upper and lower pannel and inner panel with necessary reinforcement by following the master section with the design parameters as per given Class surface A.

First,we have given

Design of Back door in NX CAD:

Door parts thickness is given below,

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

Firstly we can see that there is a flange on upper body we have to create same at lower body

before that we have to check surfaces are in proper manner or not by using sew opion if there is any discountinuity like given below

So for tha case we hide that surface and create a new surface by using bridge curve and through curve mesh

and repair them.

and after all the faces repair we get our improved surface

and updated lower body

First, 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 offset the part and create a sealing flange by using various command

Offset

Timesheet

project curve on the face

bridge curve and through curve mesh

sew

Then after that we create a flange by using law extension at 35 degree outward direction and using the tooling axis as specify vector that helps while creating the part

WIND SHIELD- After that creating connecting flange we we work on wind shield area and other fixing component area like wiper reinforcement,hinge reinforcement.

After that we create a line for measure path of trajectory and create reinforcement for latche

After that we mirror and sew the inner panel and after that we apply thicken 0.75 upward direction

DRAFT ANALYSIS:-

Draft analysis design is done to show that the part can be easilly draw out from the mould.

so the above design has been analysed using the tool on NX CAD with having 7 dgree as the allowance.

Steps used while creating inner panel

For lower substract

For upper body

Assembly:

In this assembly Top down approach was followed wherein from given styling surface the inner panel was created using various tools/commands in NX. After that others parts were modelled as per the requirements one by one

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