Design of backdoor

AIM:

      The objective of this project is to design a BIW back door of a car with inner panel, outer panel and the reinforcements for the hinges, Gas stay, wiper Motor and latch by following the engineering standards. The inner panel must be subjected to draft analysis for verifying whether it satisfies the deep drawing requirements for the tooling direction created.

INPUT

THEORY

HATCH BACK

The hatchback is a vehicle type which has a characteristic separate opening or door that provides access to the cargo area or boot. This door is known as 'hatch'. and thus the manufactures term this category of cars as a 'hatchback'. Although it is different than a coupe.

The hatch in a hatchback incorporates the rear glass. this door generally hinges at the top end of the rear body panel. Thus, after the entire door flips upward and provides access to the cargo area.

Because of the ease of access people prefer the hatchbacks when they need to transport a large quantity of material it is also useful when they need to open/close the door frequently to keep/remove the material from the car. some hatchback vehicles also provide the facility to fold the rear seats which adds significantly to the storage space.

How hatch works

In general, these cars are either available as three or five door versions. Three door hatchback consists of two doors for the passenger entry amd third for the luggage. similarly, in five-door version, it is four plus one combination. it has four doors for the passengers and one for keeping/removing the luggage.

ADVANTAGES OF HATCH BACK

These types of cars are very popular in many parts of europe because of their compact dimensions and large storage space. maruti 800 is the legendary entry-level hatchback in india which crossed sales figure of 2.5 million units since its launch. similarly, Tata indica launched by tata motors received a record 115,000 bookings during the first phase of its launch.

BACK DOOR

The back door is a hinged door/tailgate at the rear of the vehicle. it may be used for loading and unloading cargo, or to get passengers in and out, in case there are seats present at the rear. The back door comprises of certain components which form the back door assembly together.

The Back door of a car is the rear most part of the vehicle which gives access to the trunk space of the vehicle. the rear door also supports the reinforcements and added weights of the wiper motor, Gas stay, Tall lamp,latch and striker. the back door is usually made of an inner panel and 2 or 3 separate inner panels joined together by hemming or spot welding wherever necessary.

TYPES

Top Mounted

These type of back doors are used in a station wagon,pickup truck and some other sports utility vehicles. Today's modern cars use top mounted taligating systems which are both powered and also gas stay supported. These tailgates provide greater rear visibility compared to other types.

BOTTOM MOUNTED

Bottom type or split type backdoor system is used in estate types cars, pickup trucks and some luxury SUVs. These are most convenient type of backdoor in which the bottom split is used as a table for the touring people.

JOINING MECHANISM 

SPOT WELDING

also called resistance spot welding, spot welding continues to be the main choice of joining processes in the body shop.

It is a solid-state welding method and is used for joining overlapping sheet metals in projects which strength and durability are not pressing.

workpieces are held together under the force exerted by electrodes.

spot welding has fewer applications and tends to harden and wrap workpiece materials.

low-carbon steel is the most suitable material for spot welding.

ARC WELDING

Arc welding is one of the most prominent types of welding. Arc processes involve using the concentrated heat of an electric arc to join metal materials.

The arc can be either manually or mechanically guided along the line of the join,while the electrode either simply carries the current or conducts the current and melts into the weld pool at the same time to supply filler metal since all the metals react chemically to oxygen and nitrogen in the air when heated to high temperatures by the arc. once cooled, the molten metals solidify to form a metallurgical bond.

METAL INERT GAS WELDING

MG welding is the most widely used arc welding technique in BIW joining. Aluminium parts have been largely joined by means of MG (Metal inert gas) welding in lightweight car manufacturing. this technique is principally used to make joints between castings,extruded sections and sheet-metal parts. this gas protects the weld area from atmospheric gases such as nitrogen and oxygen, which can cause problems if they come in contact with the electrode, the arc, or the welding metal.

DESIGN PROCEDURES

THICKNESS REQUIREMENTS

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

CLASS A corrections

To begin with the given surface should be checked to figure out issues like sharp edges,discontinuity and roughness.backdoor outer upper and lower class a surface has to be repaired according to yhe smoothness. After repairing the surfaces, the door is divided into two parts as door outer upper and door lower panel.

SEALING FLANGE

This sealing flange is that section of the inner panel which enables the backdoor to sit over the rear body side of the car. it is the most important part of the inner panel as it decides how a backdoor is mounted on the rear body side of the car and also restricts any external matter to enter inside the vehicle.

REINFORCEMENTS

Required thickness=1.5mm

HINGE REINFORCEMENTS

A hinge is a mechanical bearing that connects two solid objects,typically allowing only a limited angle of rotation between them.

Hinges support the weight of the whole backdoor.hence the reinforcement must be provided there too. The emboss is designed in such a way that the hinge should operate freely. The hinge is connected to the rear of the car.

GAS STAY REINFORCEMENT:

Gas stay reinforcement is used to lift the backdoor automatically. There are two types of gas stay one is semi=automated type of the back door needs little force to lift after that it lift the back door automatically in fully automated, it has power spindle which lift the back door automatically.

RESULTS

CONCLUSION

The back door assembly is designed by following the engineering standards from the given styling surface.

1. sealing flange of length minimum 25mm is a maintained throughout.
2. Thickness for the reinforcement is 1.5mm
3. Emboss are drawn with respect to the tooling axis so that they clear the minimumdraft angle.
4. corner relief is given to prevent unwanted deformation of the sheet metal at the corners while hemming.
5. Draft analysis was performed on the inner panel and all the reinforcements were designed and placed at appropriate positions.