Design of backdoor

BACKDOOR DESIGN

AIM: to design a sheet metal panel of backdoor from the provided skin data taking all the design rule into considering.

Abstract: A back door of a car also known as tail gate is a commodity which normaly serves the purpose to covering the car from the rear end. there are more function that come with it which has to be consider while making design of the same like rear visiblity criteria and boot space. this part is usually designed keeping the master section of the rear roof rail because of the sealant flanges and also varius other component.

OBJECTIVE:

1. From the given styling surface develop a back door using approptiate design methadology.
2. The obejective of this project is to design BIW back door of a car with an inner panel, Outer panel and reinforcement for the Hinges, Gas stay, wiper Motor and latch by the following engineering standard.
3. the inner panel must be subjected to draft analysis for varifying whether it satisfied the Deep drowing requirement for the tooling direction in the design.

SOFTWARE USED:

Siemens NX CAD (UNIGRAPHICS)

INTRODUCTON:

The backdoor of car is the rearmost part of the vehicle which gives acces to the trunk space of the vehicle. The rear door also support the reinforcement and added weights of the wiper motor, Gas Stay, tail lamp and latch and striker.

the backdoor/tailgate is one of the closure commodities in BIW sheet metal design. The backdoor has a lot of component inside and is designed to incorporate them easily. it effect the rear visiblity and luggage area.

The material used for the door manufacture depend on the budget and performance of the vehicle. mostly aluminium amd steel are used where as low budget vehicle use steel which make the manufacturing process easy and cost-efficient since it follow the stamping of moulds.

MAJOR PART AND REINFORCEMENT:

The backdoor consist of the following basic component.

1. backdoor outer panel (Upper)
2. backdoor outer panel (Lower)
3. backdoor inner panel
4. hinge reinforcement (LH & RH)
5. gas Stay Reinforcment (LH & RH)
6. latch and striker Reinforcement
7. wiper motor reinforcement

TAILGATE/BACKDOOR:

Tailgate is a door at the back of a truck or car, that is hinged at the bottom so that it open downwards.

DESIGN INTENT

The intent of the project is to design a body in the white back door of the vehicle considering the engineering standard and manufacturing requirement which satisfies the deep drawing process.

DESIGN CONSIDERING OF A BACKDOOR:

• Functional requirement of Hinge and gas stay
• Rear visibility criteria
• luggage volume
• crash analysis
• bend test, Dent test, torsion test, and Endurance test
• rear Crash regulation
• gap and flushness requirements

EMBOSSES

Emboss is the metal forming process for producing raised or sunken designs or relief in sheet material 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.

HEMMING
Hemming is the forming operation in which the edge of the sheet is folded or folded over another part.

IT HAS TWO TYPES

1. CONVENTIONAL DIE HEMMING: In this, the flanges are folder over the entire length with the hemming tool.

2. ROLL HEMMING: In this, the hemming roller is guided by an industrial robot to form the flanges.

BLANKING:

Blanking is a cutting operation of a flat metal sheet and the article punches out is known as blank. Blank is required as a product and another part as a waste.

PUNCHING:

It is similar to the blanking in this the hole is the required product and the material punched out the hole and is considered as a waste.

Door test video link: https://www.youtube.com/watch?v=BcbBpNbziaU

DESIGN METHODOLOGY:

DESIGN OF BACKDOOR DOOR OUTER PANEL:

The outer panel is the styling surface of the backdoor. Other components of the backdoor are designed with reference to the outer panel. it acts as the outer cover and deals with the aesthetics of the car.

it has two-part.

1. Outer Upper Panel

2. Outer lower Panel

1. OUTER UPPER PANEL

• The outer panel is extracted from the styling surface.
• The panel is altered for the required design with the surface tool of NX CAD
• The thickness is 0.75 mm
• hemming is provided with the corner relief

2. OUTER LOWER PANEL

• The outer panel extracted from the styling surface.
• The panel is altered for the required design with the surface tool of NX CAD
• The thickness is 0.75 mm
• hemming is provided with the corner relief

TOOLING DIRECTION

• before starting to design the inner panel of the back door the tooling direction for deep frowing pupose should be created
• then the styling surface needs to be checked and analyzed since it might have irregularities, hence it must be fixed first.
• then the backdoor is design using the top down approach

DESIGN OF BACK DOOR INNER PANEL

• The INNER panel extracted from the styling surface
• The panel is altered for the required design with the surface tool of NX CAD
• The thickness is 0.75 mm

EFFECTIVE FLANGES

• After creating the tooling direction the design of the inner panel will begin where we will first develop an effective flange by checking all boundaries and by following the shape of the inner panel design.
• by creating multiple flanges and by using surface modeling technique the concept design of the inner panel was created
• after the concept of the inner panel is developed than the child component like a hinge, latch, gas stay, and their reinforcement must be designed which completes the overall design of the backdoor.
• The embosses were created in V-shape or y shape so that if the vehicle undergoes the crash then the force dissipates over it which reduces the damage transferred to the tank space

MASTIC SEALANT

The mastic sealant is used to fix the inner panel to the outer panel which increase the NVH factor and stiffness of the back door

HINGE, GAS STAY, AND WIPER MOTOR EMBOSS

• The red circle denotes the hinge emboss which was created using the detum plane and emboss feature in NX. it also designed in a way that the emboss should have a flat surface for assembling the hinges using it.
• The violet circle denotes the gas stay emboss which was created using the surface of the connecting flanges
• the yellow circle denoted the wiper motor

LATCH AND STRIKER EMBOSS:

The latch and striker emboss were designed by creating a trajectory that follows the opening and closing of the back door with respect to the hinge axis.

STRIKER POSITION:

the position of the hinge should be perpendicular to the latch when the latch and striker meet. The circle is drawn from the center of the hinge axis to find the path of the striker.

HEMMING:

Hemming and seaming are two similar metalworking processes in which a sheet metal edge is rolled over onto itself. hemming is the process in which the edge is rolled flush to itself.

• the outer panel was designed as two separate parts named as outer panel upper and lower.
• After designing the outer panel the hemming was created by offsetting the surface with the help of face blend and swept surface.
• The two separate outer panels will be joined using blanking.

CORNER RELIEF

During the hemming process when giving the corner relief it controls the sheet metal material behavior and prevents unwanted deformation during operations and also helps to reduce the number of passes in hemming.

DESIGNING THE REINFORCEMENTS

The thickness of all reinforcement is 1 mm.

• hinge reinforcement
• gas stay reinforcement
• wiper motor reinforcement
• latch reinforcement

note: All the reinforcement were created using the same method first linked the body was created separately for each with the help of extract geometry and then the required portion was trimmed out then thickened

HINGE REINFORCEMENT

Hinge enables the opening and closing of the backdoor. one end is fixed on the back door and other end to the roof. hinges can be placed outside or inside the backdoor.

The hinge reinforcement are added to compensate for the weak region due to acting load over it.

GAS STAY REINFORCEMENT:

Gas stay is a devise for supporting the back door in its open position. Gas stay requires no manpower and is engaged into support position automatically as the backdoor opens. one end is fixed with the backdoor and other end is fixed with the bosy side or on the back door stationary area.

Embossing is provided at the gas stay mounting area to compensate weakness and improve strength.

WIPER MOTOR REINFORCEMENT:

Wiper motor reinforcement is crated to mount wiper motor assembly.

LATCH AND STRIKER REINFORCEMNT;

The latch and striker form the locking mechanism of the backdoor with the car. due to regular opening, closing and over slamming of the backdoor, there is stress developed in the latch and striker.

Embossing is provided at the latch and striker mounting area to compensate weakness and improve strength.

DRAFT ANALYSIS:

• The draft analysis will be performed for the tooling direction created at first and checked that the model is suitable for manufacturing.
• Then to get a complete green portion the necessary changes to the draft angle of the embosses were carried out by optmizing the model.
• The draft analysis command enable us to detect that the part drafted will be easily removed or not.
• This type of analysis is performed based on the color range identifying zones on the analysis element where the deviation from the draft direction at any point corresponds to the specified value.