Design of backdoor

Back Door

The cars in India has mainly five doors , Front and back doors at the left and right side and the rear door. Mostly rear door is used for the access to the boot space of the car, but in some suv the rear door will gave an access to the 6 th and 7 th seats .

The back doors of suv each car is entirely different. It changes with respect to hatchback,suv,sedan or coupe etc..

A hatchback is a car with a cargo-access door  on the rear of the vehicle that opens to the passenger compartment. The hatch is typically a liftgate with hinges on the top, so it is simple to open and pass cargo through.

PARTS OF BACK DOOR 

• outer panel
• outer panel lower
• inner panel 
• wiper motor reinforcement 
• latch and striker reinforcement
• hinge reinforcement 
• gas stay reinforcement 

For suv , the backdoor sometimes give access to passengers seat or sometimes gives access to cargo.

Also the opening axis (hinges) of suv back doors varies .Some have horizontal axis and some have vertical axis.

ie they are of three types ,

• Top mounted
• Side mounted
• Bottom mounted

Our project is design the back door were the outer panel is given but the inner panel we have to design ourself.And should design the reinforcements for gasstay ,hinges,latch,wiper motro et

The back door is held by hinges and gas stay . To lock a latch and stricker is proveded.Also for luxury vehicle electric motors are used.

Also the space for wiper motor,  rear lamps, ets are given in between the inner panel and outer panel.

here we are designing top mounted back door.

 DESIGN CONSIDERATIONS

• Visibility Criteria
• Force Dissipation
• Gas Stay Position 
• Material Selection 
• Space Availability 
• Hemming and Relief Areas
• Latch and Stricker Positions
• Hinge Position

Force Dissipation

Latch and Stricker Position

The latch and stricker should collide in perfect way  while closing,so we draw the axis of the back door between the hinges and draw a circle which axis as the center and hits the latch normally,only if the centre points and the tangent line are perfect the opening and closing of the back door is smooth and clear. or else the Hinge positions,

Visibility Criteria

Visibility of the rear view should not be restricted by the design of back door.The blind spots should be minimized .

Hemming and relief areas

Hemming is a sheet metal process where the edges of the sheet metal is bended onto itself to provide a joint. we use hemming for joining inner panel and outer panel. The inner panel is locked in between the bending of outer panel.after hemming we use a sealant coating to provide a air tight fit and for good appearance. In corner areas ,we must provide a hemming allowance for proper bending of the sheetmetal.

The 3 major components of back door are

OUTER PANEL

INNER PANEL

REINFORCMENTS

OUTER PANEL

Outer panel is the outer most and aesthetic surface of the back door of the car. . mostly, outer panel desingned to be two parts, there outer panel lower and upper. the rear lamp area is also provided on the outer panel. sometimes the number plate is also mounter on the bak door so we need to provide a sufficient area for the number plate .edges of the outer panel consist of hemm used to joint with the inner panel.

INNER PANEL

 Inner panel consist of sealing flange area,wiper motor area, gas stay area,hinge area and latch and striker area. sealant flange is provide to create  a air and water tight conact between weather strip and inner panel. weather strip is a rubber component which is mounted on the rear edge of the car body boot area to provide a air and water tight joint.

we must create embosses on the inner panel to dissipate the force whenever the rear collision happens. also provide a rear wiper motor mounting nearest to the wind shield area. this mounting is also attached to the outer panel by using mastic sealing for provide sufficient joining between outer panel and inner panel. About 0.2 mm gap is provided between inner panel and outer panel

REINFORCEMENT

1:hinge reinforcement

2:gas stay reinforcement

3:wiper motor reinforcement

4:latch and stricker reinforcement

DRAFT ANALYSIS

Draft analysis is done with tooling axis we crated to get better tooling and reduce the cost of production.