Hood design-Week 2

HOOD DESIGN-CHALLANGE

Introduction:

Hood is main component ofacar at the front portion.It is used to decorate the car&add luxurious look.The shape of the bonnet is made aerodynamic in order to minimize the air effect.

Hood design consideration:

The hood ofacar is considered as the frontal BIW enclosure component.Bonnets are designed to reduce air resistance as the air flows around the car.Apart from this,bonnets are also designed to meet several other requirements.They serveagreat deal of purpose in protecting the passengers inside the car&the pedestrians in the event of an accident.It also acts as the cover for the engine.

• The European New Car Assessment Programme(Euro NCAP)isaEuropean car safety performance assessment program which has developed test specifications&rating systems for assessing pedestrian injuries during impacts with the front of vehicles such test includeaseries of tests using impacts designed to bio-mimic a collision at speed of 40 km/h.

• They describeasituation in whichapedestrian is situated laterally&acar first hits one of his legs.Test are conducted on the leg,upper leg&most importantly the head,as head trauma is most commonly responsible for casualties.

• So to avoid severe injuries to the head,the high impact area for adults&children are subjected to less thickness.Also no reinforcement should be provided in that area as during head collision,the hood will absrob the head impact energy leading to collapse of the hood&thus protecting severe head injury.

• Another important criteria for the hood design is the protection of the occupants inside the car during front collision.The design of the hood should be inasuchaway that the during the collision,the force should travel in the upward direction through the embosses&directed towards the body of car.Thus protecting the occupants inside.

Following parts are using in hood assembly for this report,

1. Hood outer panel

2. Hood inner panel

3. Hinge assembly

4. Striker assembly

Hood thickness

Outer panel thickness=0.75 mm

Inner panel thickness=0.75 mm

Reinforcement thickness=1.5 mm

Inner Panel -

• In the inner panel only we can research&implement the safety of pedestrians&as well as the driver. In this panel only we can attach the reinforcement,embossed,mastic points etc.

• It is an object of the present invention to provideahood inner panel capable of reduction ofareaction force of the hood inner panel even ifalevel of deformation ofahood ofavehicle increases,&ensuringasufficient energy absorption capacity.

Outer Panel -

We can also call it as cover of inner panel.It is the part,which gives luxurious look to the hood or bonnet.Outer & inner panel can not join by any welding process like spot welding or rivet,which spoil the outer look of a car.The outer panel is generally extracted model from the prototype design.

Hinge Assembly -

Hinge isacomponent that fixes the hood to the fenders of the car.The latch must be fixed perpendicular to the hinge axis so that the hood opens or closes properly.

Striker Assembly -

Latch&striker is used for locking the hood with the car.It is usually placed on the space provided on the inner panel.

The process involved in designing hood asasheet metal operations is

● Blanking
● Hemming
● Punch cutting or piercing
● Deep drawing
● Embossing

Hemming-

• Hemming isasheet metal forming process in which sheets are joined by bending it usually to 180 degree. Automotive body panels&parts such as deck-lids,trunk-lids,doors,hoods&tailgates are formed by hemming processes.

• Roll hemming is carried out incrementally withahemming roller.An industrial robot guides the hemming roller &forms the flange.Roll hemming operation can also be divided into several pre-hemming&final hemming process steps.

• Coventional die hemming is suitable for mass production.In die hemming,the flange is folded over the entire length withahemming tool.Normally the actual hemming isaresult ofaforming operation in which the flange is formed withahemming tool after the drawing&trimming operations have been completed.

While doing the hemming processarelief angle is formed asaproduct of hemming when attaining at the corner of
the sheet.

Deep Drawing-

• Deep drawing is a manufacturing process that is used extensively in the forming of sheet metal intoacup or box-like structures. Pots & pans for cooking,containers,sinks,automobile parts,such as panel & gas tanks,are among a few of the items manufactured by sheet metal deep drawing.

• A deep drawing of sheet metal is performed withapunch and die.The punch is the desired shape of the base of the part,once drawn.The die cavity matches the punch and isalittle wider to allow for its passage,as well as clearance.For many calculations, the sheet metal thickness is assumed to remain constant.There are changes in thickness in certain areas,due to force involved.

Embossing -

• The sheet metal embossing operation is commonly accomplished withacombination of heat&pressure on the sheet metal , depending on what type of embossing is required.

• Asheet metal is drawn through the male&female roller dies,producingapattern or design on the sheet metal. Depending on the roller dies used,different patterns can be produced on the sheet metal.

Latch trajectory -

While opening or closing the hood,the latch must be perfectly aligned to the fixing or striker point.For that, the latches trajectory must be perpendicular to the hinge axis.

Hood Assembly- Output -

Conclusion -

We have designedahood that falls under the rules&regulations of the manufacturer's standards.