Design of backdoor

Back Door/Tail Gate Design

Design considerations for Back Door:

1)Rear visibility criteria

2)Luggage space

3)Rear crash reinforcements

Sealing flange is the surface used to mount sealant/rubber.Sealant is the protection that to avoid entering water into the car.This is to be deigned corresponding with Rear lower panel,Roof rear flange,Side body flange.

There are two types of materials using for Back door.

1)Aluminium

2)Steel

Reinforcements provided at back door

1)Latch & striker

2)Hinge-2 Nos

3)Gas stay-2 Nos

4)Rear wiper motor

There are some Analysis or Testing methods while manufacturing any BIW parts of automotive

1)Bend test

2)Torsion test

3)Abuse test

4)Dent test

5)Assembly load case

6)Endurance test

Hinge mounting may be outside or inside

Gas stay mounting may be either on body or door

Now a days in higher end models power strokes are using for back door operation instead of gas stay.

We will provide 'Y' embosing to distribute vibration of hitting effect towards outside.

Back door forming done by stamping process.After copletion of all indivual parts,we will use hemming to join all the parts together.Brazing & Mastics using for for joining process.

Assembly sequence of Car back door:

Joining between inner & outer panel using brazing.Mastics also using for panel joining purpose.

Hinge axis,striker position & Gas stay position has corelated functions.

Class A surface correction:

       Given class A surface has lot of patches.So we have to correct all the patches.Smooth surface created with new surfaces.

Outer top panel:

This part is the rear outer most surface of our car body.

Rear crash analysis is the main criteria for this part.

We have extracted this part from corrected class A surface.

Hemming is the joining process of two parts using in manufacturing.While creating hemming flange we have to provide gap between inner & outer panel 0.2mm on both sides.This is for sealant applying purpose.

After all surface corrections ,we have provided proper fillets at all smooth curve areas.Mirrored surface & applied sew operation.

In outer panel we have provided cutouts for Rear lamp mounting & Rear glass fixing.

Draft angle analysis done for outer top panel.It found ok for minimum angle of 7 degree.

Outer Lower panel:

This is lower part of the outer panel. We will join both top & lower panel using brazing operation.

Extracted given corrected class A surface of lower panel.

After completion of all surface work ,we have provided hemming provision.

Hemming is manadatory to join this panel with inner panel.

It is creted with 0.75mm thickness.

Draft angle analysis done.There found negative draft & zero draft surface.But this surface given in class A.So we can't change it now.

Inner panel:

Sealing flange created with 25mm depth.

This part is to mount sealant through out the back door.Sealant will protect water entering into the car.

Flange surface created & joined with panel surfaces.

This step we have provided to connect inner & outer panel at middle portion of the panels.Mastics will applied on this surface.So that outer panel will stick over inner panel.

If we use welding here,it will spoil the outer surface's finishing.So we will use mastics at this area.

We have to privide multiple provisions at inner panel as per mentioned below,

Hinge (LH):

Flat surface created with some particular depth.

This embossed profile will give more strengthened surface.Holes provided for hinge fixing.

Here we have used internal hinge mounting method.

Gas stay(LH)

Gas stay is the part that will link back door with side body.It will help to hold the door at open position.Smooth operation of the door will be achieved by gas stay member.Selection of gas stay based on door weight & opening angle.

Here also we have provided flat embossed surface provision for gas stay mounting.

 

This cutout provided to fix rear lamp.After joining of inner & outer panel,we can't work inside of inner panel.But we have to fix lamp at any time.So we have provided this cutout for accessibility inside inner panel.

Embossing will create more strenght for the panel surface.

Wiper motor mounting:

Rear wiper motors using to wipeout water particles on glass surface during rainy.To fix this motor we need flat surface & holes.

Here we have provided flat embossed surface for rear wiper motor fixing.

Striker fixing:

Striker is the lock for back door.It will be locked using latch holding mechanism.

We defined striker position using hinge center axis tajectory method.Position of striker plate corresponding with hinge alignment.So both have correlated alignment.

We followed same method already done in Hood design.

Created circle center with hinge axis center point.Then line created between circle center & outer for some angle.Then another line created with perpendicular for that line.This line also tangent to circle.This line is striker movement direction.

Then embossed flat surface created for striker mounting.

 

Fillets provided at required places to create smooth surface finish.Then thickness applied for 0.75mm.

 Draft angle analysis applied for minimum draft angle of 7 degree.

Back Door assembly:

Cut section of Back door

Proper alignment of Outer panel top,lower & Inner panel showed in last image.